Serous Fluid
Fluid in the body that resembles serum, can be transudate or exudate.
Transudate
a fluid consisting mostly of water moves out of the blood vessel into the body cavity.
Transudates are formed by two mechanisms. In both cases, capillary permeability is normal, allowing preferential filtration of water over protein. An increase in hydrostatic pressure in the venous circulation without a significant change in osmotic pressure will result in increased fluid production. This mechanism causes effusions in congestive heart failure. A decrease in the concentration of plasma proteins is another common cause of transudates. The decrease in plasma proteins causes a decrease in osmotic pressure. This is a common cause of effusions in malnutrition and cirrhosis.
Transudates appear as clear pale or yellow fluids.
Exudate
a protein-rich fluid in the body cavity.
The causes of exudate production are more complex, but generally involve two mechanisms. In both cases the usual result is a protein-rich body fluid. The first mechanism is an increase in the permeability of the capillary wall to plasma proteins. This is seen in a variety of inflammatory conditions such as bacterial infection. The second mechanism is the introduction of certain foreign substances into the body cavity. These substances increase the amount of protein and other osmotically active materials in the body cavity, and tend to draw water out of the blood vessel.
Transudate v. Exudate
A variety of morphologic and chemical findings may be used to differentiate transudates from exudates. Of these, the ratios of total protein or lactate dehydrogenase (LDH) in fluid relative to serum are the most reliable. Differences are also seen in the appearance, white blood cell count, and specific gravity of transudates and exudates. However, significant overlap exists and they should not be relied upon to make this distinction.
Turbid serous fluid
The presence of numerous particles in fluid results in a turbid gross appearance. This is commonly seen in bacterial infection where the particles are neutrophils and cell debris. These fluids often have a yellow-green color due in part to neutrophil enzymes, in particular myeloperoxidase. Empyema refers to the presence of pus in a body cavity.
Hemorrhage in serous fluid
Hemorrhage into a body cavity results in grossly bloody fluid. The red color is a result of the presence of numerous erythrocytes, and may range from light pink to deep red depending on the number of erythrocytes present. Only 0.2% blood is necessary to impart a pink color to a fluid. Situations where a bloody fluid may be seen include malignancy, trauma, or organ infarction. Malignancy is the most common. When severe, hemorrhage into a body cavity can result in the formation of blood clots. Often the clots may be seen grossly. Transudates do not form clots.
Bile in serous fluid
Bile imparts a deep green color to body fluids. Bile is formed in the liver, stored in the gall bladder and released into the lumen of the small intestine. A rupture or pathological hole (perforation) through any of these organs can result in the leakage of bile into the abdominal cavity and give rise to a bile-stained fluid.
Chyle in serous fluid
Chyle is a milky fluid consisting primarly of lymph and triglycerides. It is present in the thoracic duct, a structure which drains lymphatic fluid back into the circulation. Trauma to the thoracic duct or malignancy can result in release of chyle into the pleural cavity. This is known as chylothorax, and is rare. More commonly, a chronic effusion in conditions such as rheumatoid arthritis or tuberculosis may have a chylous appearance. This is called pseudo-chylous effusion and the characteristic appearance is due to cell debris and cholesterol crystals.
Cell counts
Cell counts can be manually determined using the Neubauer Hemocytometer, which consists of two chambers with an overlying coverslip. A dilution of fluid is added into each chamber, and a count is made of the number of each cell type that fall within specified regions.
Cytocentrifuge
The cytocentrifuge is used to concentrate cells onto the surface of a glass slide. The slide is then stained and examined microscopically to generate a differential cell count and to evaluate for the presence of malignant cells.
Wright Stain
The Wright stain is used for the identification of normal and neoplastic hematopoietic cells on either smears or cytocentrifuge preparations. A slide containing the cells to be stained is first covered with Wright stain and allowed to sit for 2 minutes. An equal amount of buffer is then added and allowed to sit until a green sheen develops, roughly 5-7 minutes, and then quickly rinsed with water. The slide is then allowed to air dry and a coverslip may be applied to prevent damage to the stained cells. The nuclei of cells stain purple or lavender and the cytoplasm stains pale blue (lymphocytes and monocytes) to pink (neutrophils).
Description of RBC
Red blood cells (erythrocytes, RBC) are identified by pink color, small size and absent nucleus
Increased by hemoconcentration, drugs, altitude, smoking
Decreased by hemodilution, pregnancy, drugs, sampling technique
Hemodilution
Reduced RBCs in a blood sample due to bolus of saline, excess water intake, excess sodium intake
Hemoglobin
(Hg or Hgb)
Transports oxygen and is the main component of RBCs
Correlates closely to RBC count
Good indicator of anemia
Increased by dehydration, polycythemia
Decreased by anemia, hemorrhage, fluid retention (hemodilution)
Hematocrit
(Hct)
Reflects the proportion of blood occupied by RBCs
Measures % by volume of packed RBCs in a whole blood sample
If HCT is 40% --> a 100 ml sample contains 40 mL of packed RBCs
Increased by polycythemia, dehydration
Decreased by anemia, hemodilution, blood loss
H&H
Hemoglobin & Hematocrit
Similar interfering factors, increasing and decreasing, as with the RBC count
Verification - Compare RBC, Hgb and Hct
Rule of three
WBC
leukocytes
Useful to aid in the diagnosis of infection and inflammation
Can monitor a pts response to chemo or radiation therapy
Helps decide if further testing is needed
Neutrophils, eosinophils, basophils, lymphocytes, macrophages, plasma cells, mesothelial cells.
Leukocytosis
An increased white blood cell count above the normal range
Infection
Abscess, meningitis, appendicitis, tonsillitis
Leukemia
Tissue necrosis
Burns, MI, gangrene
Hemoconcentration
Leukopenia
A decreased white blood cell count below the normal range
Bone marrow depression
Due to viral infection or toxins
Seen in influenza, typhoid fever, rubella measles, infectious hepatitis, mononucleosis
Hemodilution
Description of neutrophils
2/3 of WBC
fine and pale pink granules in the cytoplasma
type of WBC with segmented nuclei
Description of eosinophils
coarse and red granules in the cytoplasm
type of WBC with segmented nuclei
Description of basophils
coarse and purple granules in the cytoplasm
type of WBC with segmented nuclei
Description of lymphocytes
1/3 of WBC
small WBC which has scant, pale blue cytoplasm and a round nucleus
type of WBC with nonsegmented nuclei
Description of macrophages
abundant pale blue vacuolated cytoplasm and larger folded nuclei
type of WBC with nonsegmented nuclei
Description of plasma cells
round nuclei with coarse chromatin, and eccentric deep blue cytoplasm with perinuclear clearing
type of WBC with nonsegmented nuclei
Description of mesothelial cells
a cell type unique to serous fluids, as they represent the cells which line serous body cavities. Mesothelial cells are characterized by very round nuclei, often with a single discrete nucleolus, and abundant blue cytoplasm having a frayed cytoplasmic border and perinuclear clearing or "halo". They are often said to have a "fried egg" appearance.
type of WBC with nonsegmented nuclei
RBC
identified by pink color, small size and absent nucleus
Neutrophil
fine and pale pink granules in the cytoplasma
Eosinophil
coarse and red granules in the cytoplasm
Basophil
coarse and purple granules in the cytoplasm
Lymphocyte
small WBC which has scant, pale blue cytoplasm and a round nucleus
Macrophage
abundant pale blue vacuolated cytoplasm and larger folded nuclei
Plasma cell
round nuclei with coarse chromatin, and eccentric deep blue cytoplasm with perinuclear clearing
Mesothelial cell
characterized by very round nuclei, often with a single discrete nucleolus, and abundant blue cytoplasm having a frayed cytoplasmic border and perinuclear clearing or "halo". They are often said to have a "fried egg" appearance.
Whole blood
Blood drawn from the body from which no constituent, such as plasma or platelets, have been removed
Plasma
The clear, yellowish fluid portion of blood, lymph, or intramuscular fluid in which cells are suspended
Serum
The clear, yellowish fluid obtained upon separating whole blood into its solid and liquid components after it has been allowed to clot
CBC with diff
Provides information about 3 types of cells - WBC, RBC and platelets
BMP
Blood chemistry tests help evaluate the body’s respiratory & metabolic status
Electrolyte levels provide data on body's acid-base balance & fluid balance
Essential components for basic body functions
Reflects basic kidney function
CMP
Same as BMP but also includes LFT
Beta hCG
Pregnancy test
Quantitative hCG, measures the amount of hCG in the blood, yields a number vs. positive/negative result
Culture, blood
used to detect the presence of bacteria or fungi in the blood, to identify the type present, and to guide treatment. Testing is used to identify a blood infection (septicemia) that can lead to sepsis, a serious and life-threatening complication. Individuals with a suspected blood infection are often treated in intensive care units, so testing is often done in a hospital setting.
PT
(Prothrombin time)
Marker of Hepatic Synthetic Function
(Liver Metabolism)
A glycoprotein produced in the liver
Necessary for firm fibrin clot formation
Measures the time required for a fibrin clot to form
Elevation indicates hepatic disease, clotting factor deficiency or anticoagulation
Extrinsic pathway
Compared with control times
Variations with methods
Coumadin therapy - INR replaces PT
PTT/APTT
(Partial Thromboplastin Time)
Intrinsic pathway
Compared with control times
Variations with methods
Heparin therapy - APTT more sensitive
Random glucose
Glucose testing on a non-fasting subject
Bleeding time
A test of platelet function
Measured as the time it takes for bleeding to stop due to the formation of a platelet plug
Provided that fibrinogen levels and platelet count is normal, this procedure will detect defective platelet function
A screening test for inherited and acquired platelet defects
Blood grouping, ABO/Rh
used to determine an individual's blood group and what type of blood or blood components the person can safely receive. It is important to ensure that there is compatibility between a person who requires a transfusion of blood or blood components and the ABO and Rh type of the unit of blood that will be transfused. A potentially fatal transfusion reaction can occur if a unit of blood containing an ABO antigen to which a person has an antibody is transfused to that person. For example, people with blood group O have both anti-A and anti-B antibodies in their blood. If a unit of blood that is group A, B, or AB is transfused to this person, the antibodies in the person's blood will react with the red cells, destroying them and causing potentially serious complications.
If an Rh-negative individual is transfused with Rh-positive blood, it is likely that the person will produce antibodies against Rh-positive blood. Although this does not cause problems for the person during the current transfusion, a future transfusion with Rh-positive blood could result in a serious transfusion reaction.
Rh typing is especially important during pregnancy because a mother and her fetus could be incompatible. If the mother is Rh-negative but the father is Rh-positive, the fetus may be positive for the Rh antigen. As a result, the mother’s body could develop antibodies against the Rh antigen. The antibodies may cross the placenta and cause destruction of the baby’s red blood cells, resulting in a condition known as hemolytic disease of the fetus and newborn. To prevent development of Rh antibodies, an Rh-negative mother is treated with an injection of Rh immune globulin during her pregnancy and again after delivery if the baby is Rh-positive. The Rh immune globulin binds to and "masks" any Rh antigen from the fetus that the mother may be exposed to during her pregnancy and delivery and prevents her from becoming sensitized and developing antibodies against the Rh antigen.
Blood typing is also used to determine the blood group of potential donors at a collection facility. Units of blood that are collected from donors are blood typed and then appropriately labeled so that they can be used for people that require a specific ABO group and Rh type.
EKG
recording of the electrical activity of the heart
Echocardiogram
An echocardiogram is a test that uses sound waves to create pictures of the heart. The picture is more detailed than a standard x-ray image. An echocardiogram does not expose you to radiation.
Stress test
A stress test, also called an exercise stress test, is used to gather information about how well your heart works during physical activity. Because exercise makes your heart pump harder and faster than it does during most daily activities, an exercise stress test can reveal problems within your heart that might not be noticeable otherwise.
An exercise stress test usually involves walking on a treadmill or riding a stationary bike while your heart rhythm, blood pressure and breathing are monitored.
Serial cardiac biomarkers
substances that are released into the blood when the heart is damaged or stressed. Measurement of these biomarkers is used to help diagnose, risk stratify, monitor and manage people with suspected acute coronary syndrome (ACS) and cardiac ischemia.
Troponin I or T, CK, CK-MB
Also myoglobin, BNP, and hs-CRP
BNP
used to help detect, diagnose, and evaluate the severity of heart failure. Testing may be performed if a person has symptoms such as swelling in the legs (edema), difficulty breathing, shortness of breath, and fatigue. It can be used, along with other cardiac biomarker tests, to detect heart stress and damage and/or along with lung function tests to distinguish between causes of shortness of breath. Chest X-rays and an ultrasound test called echocardiography may also be performed.
Homocysteine
to determine if a person has a vitamin B12 or folate deficiency. The homocysteine concentration may be elevated before B12 and folate tests are abnormal. Some health practitioners may recommend homocysteine testing in malnourished individuals, the elderly, who often absorb less vitamin B12 from their diet, and individuals with poor nutrition, such as drug or alcohol addicts.
Homocysteine may be ordered as part of a screen for people at high risk for heart attack or stroke. It may be useful in someone who has a family history of coronary artery disease but no other known risk factors, such as smoking, high blood pressure, or obesity. However, the exact role that homocysteine plays in the progression of cardiovascular disease has not been established, so the utility of the screening test continues to be questioned. Routine screening, such as that done for total cholesterol, has not been recommended.
Tests for both a urine and blood homocysteine may be used to help diagnose homocystinuria if a health practitioner suspects that an infant or child may have this inherited disorder. In the U.S., all babies are routinely tested for excess methionine, a sign of homocystinuria, as part of their newborn screening. If a baby's test is positive, then urine and blood homocysteine tests are often performed to confirm the findings.
Fasting lipid profile
used as part of a cardiac risk assessment to help determine an individual's risk of heart disease and to help make decisions about what treatment may be best if there is borderline or high risk. The results of the lipid profile are considered along with other known risk factors of heart disease to develop a plan of treatment and follow-up. Depending on the results and other risk factors, treatment options may involve lifestyle changes such as diet and exercise or lipid-lowering medications such as statins.
Myoglobin
ordered as a cardiac biomarker, along with troponin, to help diagnose or rule out a heart attack. Levels of myoglobin start to rise within 2-3 hours of a heart attack or other muscle injury, reach their highest levels within 8-12 hours, and generally fall back to normal within one day. An increase in myoglobin is detectable sooner than troponin, but it is not as specific for heart damage and it will not stay elevated as long as troponin.
Although a negative myoglobin result effectively rules out a heart attack, a positive result must be confirmed by testing for troponin.
Sometimes, a urine test is ordered to evaluate myoglobin concentrations in those who have had extensive damage to their skeletal muscles (rhabdomyolysis). Blood levels of myoglobin can rise very quickly with severe muscle injury. Urine myoglobin concentrations reflect the degree of muscle injury and, since myoglobin is toxic to the kidneys, reflect the risk of kidney damage.
hs-CRP
(High-sensitivity C-reactive Protein)
used by itself, in combination with other cardiac risk markers, or in combination with a lipoprotein-associated phospholipase A2 (Lp-PLA2) test that evaluates vascular inflammation. The hs-CRP test accurately detects low concentrations of C-reactive protein to help predict a healthy person's risk of cardiovascular disease (CVD).
High-sensitivity CRP is promoted by some as a test for determining a person's risk level for CVD, heart attacks, and strokes. The current thinking is that hs-CRP can play a role in the evaluation process before a person develops one of these health problems. Clinical trials that involve measuring hs-CRP levels are currently underway in an effort to better understand its role in cardiovascular events. These studies may eventually lead to guidelines on its use in screening and treatment decisions.
Metanephrine
Urine metanephrines testing is primarily used to help detect and rule out pheochromocytomas in symptomatic people. It may also be ordered to help monitor the effectiveness of treatment when a pheochromocytoma is removed to monitor for recurrence. Urine metanephrines testing may be ordered by itself or along with a plasma metanephrines test. Plasma and urine catecholamines testing may also be ordered, either along with urine metanephrines or as follow-up tests. Since catecholamines secretion tends to fluctuate over time, a 24-hour urine test for metanephrines or catecholamines may detect excess production that is missed with the blood test.
VMA
(vanillylmandelic acid)
used to detect and rule out neuroblastomas in children with an abdominal mass or other symptoms suggestive of the disease.
A VMA test was once frequently ordered to detect pheochromocytomas, but the preferred tests are now plasma free metanephrines, urine metanephrines, and urine or plasma catecholamine tests. The VMA test may still be ordered along with one or more of these tests to help detect and rule out a pheochromocytoma.
Cortisol
to screen for and help diagnose Cushing syndrome, a group of signs and symptoms associated with excess cortisol. Blood cortisol testing evaluates both protein-bound and free cortisol while urine testing evaluates only free cortisol, which should correlate with the levels of free cortisol in the blood. Sometimes salivary cortisol is also ordered to help detect Cushing syndrome.
Blood cortisol is also used to help diagnose adrenal insufficiency and Addison disease, conditions in which the adrenal glands do not function properly.
Aldosterone and Renin
Aldosterone and renin tests are used to evaluate whether the adrenal glands are producing appropriate amounts of aldosterone and to distinguish between the potential causes of excess or deficiency. Aldosterone may be measured in the blood or in a 24-hour urine sample, which measures the amount of aldosterone removed in the urine in a day. Renin is always measured in blood.
These tests are most useful in testing for primary aldosteronism, also known as Conn syndrome, which causes high blood pressure. If the test is positive, aldosterone production may be further evaluated with stimulation and suppression testing.
Both aldosterone and renin levels are highest in the morning and vary throughout the day. They are affected by the body's position, by stress, and by a variety of prescribed medications.
PFTs
(Pulmonary Function Tests)
A group of breathing tests combined to give an objective evaluation of lung function in disease.
Assess the degree of airway obstruction
Measure airway response to allergens
Quantify airway hypersensitivity
Determine effect of bronchodilators
Evaluate effectiveness of long-term treatment of lung disease and progression
ABG
Measurement of gases/ions within the blood that help to evaluate lung/metabolic function and identify any acid-base imbalance
Components include - pH, O2, CO2, HCO3-
D-dimer
to help rule out the presence of a thrombus. Some of the conditions that the d-dimer test is used to help rule out include:
Deep vein thrombosis (DVT)
Pulmonary embolism (PE)
Strokes
This test may be used to determine if further testing is necessary to help diagnose diseases and conditions that cause hypercoagulability, a tendency to clot inappropriately.
A D-dimer level may be used to help diagnose disseminated intravascular coagulation (DIC) and to monitor the effectiveness of DIC treatment.
Culture, sputum
used to detect and diagnose bacterial lower respiratory tract infections such as bacterial pneumonia or bronchitis. It is typically performed with a Gram stain to identify the bacteria causing a person's infection.
Sometimes lower respiratory tract infections are caused by pathogens that cannot be detected with routine bacterial sputum cultures. This is either because the pathogens require very specific nutrients to grow in culture or because they grow very slowly. When this is suspected to be the case, specialized tests may be done in addition to or instead of a routine culture to help identify the cause of infection. These additional tests include, for example, an AFB smear and culture to detect tuberculosis and non-tuberculous mycobacteria infections, a fungal culture, or a Legionella culture.
Culture, throat
A throat culture should be performed on children or adolescents to confirm the results of a rapid strep test and avoid missing infections that could lead to serious complications, such as rheumatic fever. A throat culture is more sensitive than the rapid strep test, but it may take 24-48 hours for results. According to 2012 guidelines from the Infectious Diseases Society of America (IDSA), confirmatory testing on adults is not recommended since adults have lower rates of strep throat and far lower risk of complications than children.
Rapid beta strep
used to determine whether a person with a sore throat (pharyngitis) has a group A streptococcal infection.
Monospot
(Mononucleosis Spot Test)
used to help determine whether a person with symptoms has infectious mononucleosis (mono). It is frequently ordered along with a complete blood count (CBC). The CBC is used to determine whether the number of white blood cells (WBCs) is elevated and whether a significant number of reactive lymphocytes are present. Mono is characterized by the presence of atypical white blood cells.
Urinalysis with microscopy
typically be done when there are abnormal findings on the physical or chemical examination of urine. It is performed on urine sediment to detect RBCs, WBC, epithelial cells, microorganisms (bacteria, yeast, trichomonads), casts, crystals.
Culture, urine
ordered when symptoms indicate the possibility of a urinary tract infection, such as pain and burning when urinating and frequent urge to urinate. Antibiotic therapy may be prescribed without requiring a urine culture for symptomatic young women who have an uncomplicated lower urinary tract infection. If there is suspicion of a complicated infection or symptoms do not respond to initial therapy, then a culture of the urine is recommended. Pregnant women without any symptoms may be screened for bacteria in their urine, which could affect the health and development of the fetus.
A urine culture may be ordered with a urinalysis or as follow up to abnormal results on a urinalysis.
BUN
(Blood Urea Nitrogen)
used, along with the creatinine test, to evaluate kidney function in a wide range of circumstances, to help diagnose kidney disease, and to monitor people with acute or chronic kidney dysfunction or failure. It also may be used to evaluate a person's general health status when ordered as part of a basic metabolic panel (BMP) or comprehensive metabolic panel (CMP).
Creatinine
used along with a BUN (blood urea nitrogen) test to assess kidney function
Creatinine clearance
used to help evaluate the rate and efficiency of kidney filtration. It is used to help detect and diagnose kidney dysfunction and/or the presence of decreased blood flow to the kidneys.
In people with known chronic kidney disease or congestive heart failure (which decreases the rate of blood flow), the creatinine clearance test may be ordered to help monitor the progress of the disease and evaluate its severity. It may also be used to help determine if and when kidney dialysis may be necessary.
BUN/Creatinine Ratio
The ratio of BUN to creatinine is usually between 10:1 and 20:1. An increased ratio may be due to a condition that causes a decrease in the flow of blood to the kidneys, such as congestive heart failure or dehydration. It may also be seen with increased protein, from gastrointestinal bleeding, or increased protein in the diet. The ratio may be decreased with liver disease (due to decrease in the formation of urea) and malnutrition.
Therapeutic drug level
the measurement of specific drugs at timed intervals in order to maintain a relatively constant concentration of the medication in the bloodstream. Monitored drugs tend to have a narrow "therapeutic index," a ratio between the toxic and therapeutic doses of medications. For some drugs, maintaining this steady state is not as simple as giving a standard dose of medication. Each person will absorb, metabolize, utilize, and eliminate drugs at different rates based upon their age, general state of health, genetic makeup, and the interference of other medications that they are taking. These rates may change over time and vary from day to day. Changes in the rate may also occur in various disease states or through interaction with other medications.
Blood alcohol level
Measures the amount of alcohol (ethanol) in the blood. 0.08% is considered legally intoxicated in most states
Urine drug screen
to determine whether a person has illegal or banned substances in his or her body.
Liver function panel
(LFT)
Albumin
Total protein (TP)
Alkaline phosphatase (ALKP, AP, Alk Phos)
Alanine aminotransferase (ALT, (SGPT))
Aspartate aminotransferase (AST, (SGOT))
Bilirubin (Total; Direct)
4 categories of liver tests
Hepatocellular damage - check AST, ALT
Cholestatis - check Alk Phos, GGT
Biliary (liver) excretion - check Tbili, Dbili
Liver synthetic function (Liver Metabolism) - check Albumin, TP, Protime
AST
Aspartate aminotransferase (AST)
Serum glutamic-oxaloacetic transaminase (SGOT)
Marker of Hepatocellular Damage
A catalytic enzyme found primarily in the heart, liver and muscle tissue, also intestine and pancreas
Not very specific for liver disease
Levels elevated with any serious damage to cells
AST very high in acute pancreatitis
ETOH=AST>ALT
Ratio of 2:1 for AST to ALT
No "L" in cirrhosis (ALT)
ALT
Alanine aminotransferase
Serum glutamic pyruvic transaminase (SGPT)
Marker of Hepatocellular Damage
An enzyme primarily produced by the liver
Necessary for amino acid production
Used to evaluate level of liver damage
In early stages of liver injury, ALT surpasses AST levels and is more specific to the liver
Found primarily in hepatocytes.
Released when cells are damaged or destroyed.
Very high ALT and AST
usually only come from a couple of sources:
Acute viral hepatitis (A,B,C, HSV)
Acetaminophen toxicity/overdose
"Shock Liver"; cardiac or surgical event?
Most other causes don’t produce such high levels.
Hepatocellular Damage
Liver biopsy is gold standard
Biopsy is second only to a good history.
If a biopsy is obtained, need a sufficiently experienced pathologist to interpret it accurately;
Alkaline phosphatase
Marker of Cholestasis
Enzyme that assists in the transfer of amino acids
Sensitive for cholestasis & liver infiltration
Limited specificity
Found in liver, bone, intestines, pediatrics, placenta
Isoenzyme available to further evaluate elevated level - determine source
If elevated with GGT, suggests hepatic origin
Ideally should be measured fasting
Only alk phos has variable range depending on age/sex
Find out if pregnant - found in placenta
GGT
Marker of Cholestasis
A biliary excretory enzyme that assists in transfer of amino acids and peptides across cell membranes
Found in the liver, heart, pancreas, kidneys, etc.
Used to evaluate progression of liver disease and hepatic metastasis
Progression/regression of carcinoma associated with increasing/decreasing levels
Screening tool for ETOH abuse
GGT stays elevated longer than AST or ALT in cases of binge drinking
Amylase
An enzyme that aids digestion of complex carbs
Produced in salivary glands and pancreas
Inflammation of pancreas causes release of amylase
Acute pancreatitis:
Increases in ~2 hrs, peak at ~24 hrs, returns to normal in 2-4 days
Excreted in the urine
Order with Lipase for suspicion of pancreas dysfunction, trauma to pancreas, alcoholics, gallstones
Lipase
A pancreatic enzyme that changes fats & triglycerides into fatty acids and glycerol
Rises and falls in tandem with Amylase
Highly specific for the pancreas
Acute pancreatitis - Increases in 2-6 hrs, peaks in 12-30 hrs, remains elevated but slowly decreases for 2-4 days
Order with Amylase
Amylase also produced in salivary glands so lipase more specific to pancreas
Albumin
Marker of Hepatic Synthetic Function
(Liver Metabolism)
One of two main proteins in blood (other is globulin)
Functions to maintain oncotic pressure and transport substances
Synthesized in the liver and correlates with severity of liver disease
Decreased in malnutrition
Reabsorbed by the kidneys, therefore presence in urine → abnl renal function?
Edema can be caused by decrease in albumin level, decrease in oncotic pressure
Bilirubin
Marker of liver excretion
Produced in the liver, spleen and bone marrow
Also a by-product of hemoglobin breakdown
Total bilirubin increases with jaundice
Total Bilirubin broken down into Direct (Conjugated) & Indirect (Unconjugated, Free)
Direct or Indirect rise based on etiology
Hemolytic anemia – increased total and indirect bili
Direct Bilirubin
Marker of liver excretion
Excreted by intestinal tract
Increased with obstructive or hepatic jaundice (impaired excretion)
Directly measured
Indirect Bilirubin
Marker of liver excretion
Circulates in blood
Increased with RBC breakdown
Old RBCs, removed by the spleen, sent to the liver
Liver "adds" glucuronic acid, making these cells water soluble for excretion; now called direct (or conjugated)
Calculated from Total Bilirubin and Direct Bilirubin
Total protein
(TP)
Marker of Hepatic Synthetic Function
(Liver Metabolism)
Total amount of albumin and globulin in the serum
Serum proteins are synthesized in the liver and RE system, and constitute >100 different substances
Decreased in severe hepatic disease and malnutrition
5’NT
(Five Prime Nucleotidase)
A plasma membrane enzyme
An isoenzyme of Alk Phos found in hepatic parenchyma and bile duct cells
When coupled with elevated Alk Phos, increased levels are indicative of liver metastasis
Order for pediatric or pregnant patients
Protime
(Prothrombin time)
Marker of Hepatic Synthetic Function
(Liver Metabolism)
A glycoprotein produced in the liver
Necessary for firm fibrin clot formation
Measures the time required for a fibrin clot to form
Elevation indicates hepatic disease, clotting factor deficiency or anticoagulation
Extrinsic pathway
Compared with control times
Variations with methods
Coumadin therapy - INR replaces PT
Ammonia
(NH3)
A waste product of nitrogen breakdown during protein metabolism
It is metabolized by the liver (and excreted as urea by the kidneys)
Elevated levels may lead to encephalopathy
Order for someone in a coma
Encephalopathy
any degenerative disease of the brain, often associated with toxic conditions
Hemoccult
Stool for occult blood (aka - FOBT)
Cannot be used for vomitus due to pH
Has its own developer solution
Indicates bleeding somewhere in the GI tract
Useful for Colon cancer screening
3 days prior to and during the test period - do not eat red meat
7 days prior to and during the test period - avoid NSAIDs (ie- Ibuprofen)
If taking Aspirin, limit = 1 adult aspirin per day.
Gastroccult
Vomitus for occult blood
Cannot be used for stool testing
Has its own developer solution
Indicates bleeding in the upper GI tract only
Not useful for cancer screening
Urease breath test
Radioactive labeled urea ingested by patient
If urease activity present then radioactive CO2 is exhaled
Radioactivity is measured
Highly sensitive
Culture, stool
A stool culture is indicated for:
Persistent diarrhea
Bloody diarrhea with fever
Travel to endemic areas
Immunocompromised patient with diarrhea
Known exposure to enteric pathogens
Recent Antibiotic use (antibiotic-associated diarrhea - AAD)
Rules out:
Salmonella, Shigella, E.coli, Campylobacter species and yeast. All other pathogens require specific request based upon clinical suspicion
Clostridium difficile
a spore-forming, gram-positive anaerobic bacillus, that produces two exotoxins. It is a common cause of antibiotic-associated diarrhea.
It accounts for up to 25% of all episodes of AAD.
Stool for ova & parasite
3 Separate Specimens collected 2-3 days apart
Specific clinical information should be provided as preparation differs for different organisms.
Scotch tape prep
Scotch Tape Test for Enterobius vermicularis (aka - Pinworm)
Presenting complaint is perianal itching
Most often seen in small children
Day care increases risk
Organism is pinworm
For tapeworms the whole stool specimen is required.
Commercial kits available $$$$
Use tongue blade and clear tape
Early morning
Touch to several places around the anus
Attach to glass slide
Put in clean container
Acute hepatitis panel
used to help detect and/or diagnose acute liver infection and inflammation that is due to one of the three most common hepatitis viruses - hepatitis A virus (HAV), hepatitis B virus (HBV), or hepatitis C virus (HCV).
Hepatitis A antibody, IgM
Hepatitis B core antibody, IgM
Hepatitis B surface Ag
Hepatitis C antibody
HAV antibody, total
HBV core antibody, total
HBV surface antibody
Fecal fat
Assessment for fat malabsorption
A number of diseases of the pancreas & GI tract are characterized by fat malabsorption
The Test:
A random fecal specimen is submitted to the lab and examined under the microscope after staining with a Sudan dye ("Sudan staining")
Visible amounts of fat indicate malabsorption and this is then quantified
Fecal pH
A specimen of feces is tested for acidity
Human feces is normally alkaline
An acidic stool can be indicative of a digestive problem such as lactose intolerance or a contagion such as E. coli or Rotavirus
Fecal leukocytes
Normally, there are no WBCs in stool.
Large numbers of WBCs in the stool may be seen in chronic bacillary dysentery, chronic ulcerative colitis, colonic abscess
Monocytes are seen in Typhoid Fever
Neutrophils are seen in invasive E.Coli diarrhea, Salmonella, Shigellosis
X-ray
A powerful electric current is applied to a negatively charged cathode which "boils" off high energy electrons.
These electrons are then attracted by, and impact a positively charged anode at high speed. A large amount of energy is released as a result of this impact, some of which is in the form of X-radiation.
The X-rays produced then travel out of the "tube" and through the patient.
The radiation that penetrates the patient is then captured by a device(s) designed to produce an image.
The varying wavelengths or "strength" of the penetrating radiation, making it through the patient, is key to how the collection device will determine the images appearance.
X-ray used to evaluate
Chest - Infiltrative processes, infectious processes, pulmonary neoplasms, pulmonary emboli, atelectasis, Heart size and diaphragmatic position.
Abdominal - Bowel OBS., perforated viscous ("free air"), organomegally, large abdominal masses or fluid collections/ascites.
Skeletal - Bony fractures, dislocation, arthritic processes, bony neoplasms, growth and/or malalignment disorders.
ALARA
Radiation exposure
As low as reasonably achievable
Ultrasound
Ultrasound is produced by what is known as the piezoelectric effect.
A special crystal (called a piezoelectric crystal) is within the ultrasound probe and when excited by an electric current vibrates thus, producing sound.
The sound is produced in a frequency range much higher then the human ear can hear (>20,000 Hz). This is called ultrasound.
Sound waves travel from the probe through the patient and back to the probe again through a coupling gel applied to the patient’s body.
The returning sound waves varying speeds are interpreted by a sophisticated computer and "real-time" images are produced.
Ultrasound waves are disrupted when they come into contact with air and are completely attenuated when they come into contact with bone. Therefore, ultrasound is unable to image structures surrounded or associated with air and/or bone.
Ultrasound waves travel through water and soft tissue well. Therefore, any structure made up of these is potentially "fair game" for ultrasound provided they are not affected by air or bone.
Ultrasound used to evaluate
Abdomen - All abdominal organs and structures with the exception of bowel.
Pelvis - Both male and female GU organs.
Heart/Vessels - Most arteries and veins of moderate and substantial size throughout the body. This is done by a means called doppler which allows us to see & measure blood flow within the vessel and diagnose vascular diseases. Referred to as a duplex scan.
Thyroid gland.
Neonatal brain through fontanel
Fluid Collections - Including the abd., chest & extremities.
Breast - Including axillary lymph nodes. *Not to be used as a screening tool for the breast.
Obstetrical - To asses the proper development and anatomical structure of the fetus.
DEXA
(Dual Energy X-ray Absorptometry)
Low dose X-rays are generated and passed through the patient’s spine, hip(s) and/or forearm(s).
The differing energies of radiation which passed through the patient are received by sensitive detectors within the scan arm.
This information is then sent to a computer which determines the structures relative bone mass which is reported in cubic cm.
This becomes the patients Bone Mineral Density (BMD) value.
This numeric BMD value is then converted into T & Z scores, which are then compared to a reference table and classified as normal, osteopenia or osteoporosis. These tables are most often based on studies performed by the WHO or NOF.
DEXA used to evaluate
Osteopenia/Osteoporosis
Recent advancements allow capable DEXA units to classify and grade types of spinal compression fractures and determine total body mass indices (BMI).
CT
Computerized Axial Tomography (CAT Scan)
X-ray’s travel through the patient as the X-ray tube spins in 360° circles around the body (Called Tomography).
Detectors at the opposite end of the tube capture the x-rays that have traveled through the patient and interpret their differing wavelengths or strengths.
A powerful computer then interprets these wavelengths and digital, cross sectional type images are constructed.
Tumors suck up contrast to show whiter on CT due to increased blood flow to it.
Don't use contrast for kidney stones (looking for white horse in a snow storm)
CT used to evaluate
Brain
Sinuses
Organs & tissues of the face & neck
Chest
Abdomen
Pelvis
Soft tissues of the extremities
Joints (especially following arthrography)
Blood vessels or heart using a technique known as CT-angio (CTA)
Spinal cord following myelography.
Limitations of CT
CT has limitations detecting the presence of small to moderate sized intra-luminal lesions within the GI tract.
CT is also somewhat limited when trying to decipher between purely cystic versus solid lesions. (This is something ultrasound is really good at doing!)
MRI
The patient is placed into a powerful, enclosed or open magnetic environment (at least 30,000x greater than Earth’s magnetic field)
This field causes uniform alignment of charged ions inside the cell into positive and negative poles. The ions are usually randomly aligned in haphazard fashion in the cells.
Hydrogen atoms are highly influenced by magnetic fields and all the cells in our bodies have H+ atoms within them.
When the magnet is turned on and off the cells resonate and this resonation can be detected by sensors in the unit.
Tissues within our bodies resonate differently. These differing resonations are then captured by detectors and a powerful & sophisticated computer interprets the information thereby creating an image.
Contraindications to MRI
Pacemakers
AICD's
Cerebral aneurysm clips prior to 1990.
Neuro-stimulators
Metal joint replacements degrade the image greatly making scanning in or around these objects difficult.
Any other inplantable and/or non-removable metallic device is suspect. Ask the MRI technologist at the medical imaging center if you have any questions concerning a potentially hazardous foreign body or device.
Metformin and contrast - nephrogenic systemic fibrosis (NSF)
MRI used to evaluate
Brain & Spinal Cord
Nerves
Skeletal System & Joints.
Abdomen/Pelvis
Chest
Soft tissues of the extremities.
Blood vessels (MRA)
Gallbladder and bile ducts. (MRCP)
Breast
Prostate
Heart
Joints post arthrography
Nuclear medicine
Radioactive substances for example, Tc99m, Io131, Ga67 (depending on the type of exam requested) are injected via an IV.
The radioactive elements are "tagged" with a particle or substance which is utilized by specific cells in the body.
The radioactive substance then accumulates within cells that utilize that particular element or particle.
The radioactive energy is emitted from the cells and received by detectors (gamma-camera) surrounding the patient.
The information is then converted into an image.
For example, the skeletal system utilizes phosphates during normal metabolism. So Tc99m is tagged with MDP (monodiphosphotase particles). The skeleton absorbs the MDP particles which subsequently carries the Tc99m into the bones. Because of this a bone scan can be performed.
Nuclear Medicine used to evaluate
Skeletal system - Primary tumor or mets
Pulmonary system - Pulmonary embolism
Heart - To determine the extent of heart muscle damage.
Infectious or inflammatory processes- Abscess
Lymphoma
Kidneys - To asses renal function.
Thyroid - Detects thyroid masses/nodules and classify them as "Hot" or "Cold".
GI & GB studies - To assess gastric emptying & GB Func. (radioactive scrambled eggs)
Sentinel lymph node(s) identification - Used to identify the primary node(s) which provide initial drainage from an abnormal region in the body
Nuclear Medicine Treatment
For patients with hyperthyroidism Large amounts of Io131 can be used to ablate the thyroid gland with radiation as an alternative to surgical removal.
Mammography
A low dose of radiation is generated via an X-ray tube and passed through the breast tissue.
A film or digital collection device captures the radiation which has passed through the breast tissue and a detailed image is produced.
The breast is placed into a compression device that squeezes the breast tightly. This is necessary to limit the amount of radiation to the patient and to increase image detail. It also allows for reproducibility between examinations to assure that the breast is being evaluated the same way each time.
PET
Radioactive Fl is labeled with glucose compounds which are injected into the patient.
These compounds are then metabolized by the cells within the patient’s entire body.
Although glucose is used by all cells, more glucose is used by cells with increased metabolism.
Because cancer cells are highly metabolic and therefore, use more glucose than neighboring cells, they are easily seen on a PET scan.
Detectors surrounding the patient receive the information emanating from the cells and determine which cells have a greater amount of the radioRx within them.
An image of the entire body is produced and any areas of higher glucose metabolism are easily identified.
Same technique as nuclear medicine
Chiefly used to detect tumors
CT and PET scanner in one, get anatomy and physiology images
PET used to evaluate
PET is primarily used in the field of medical imaging to discover the presence of and/or extent of cancer.
Types of cancer that can be revealed by PET include:
Lung, colo-rectal, breast, prostate, and/or lymphatic.
PET is also used to evaluate the function of the brain of those with Alzheimer's disease, Parkinson's disease and/or seizure disorders.
PET also plays a role in the research of psychiatric and behavioral disorders.
Fluoroscopy
X-rays are produced from a conventional X-ray tube continuously.
The varying wave lengths of the X-rays that pass through the patient are collected by a device called an image intensifier which then converts this information into a real time, movie like image on the monitor.
Fluorsocopy is commonly used to image dynamic structures or when one needs to perform a procedure that requires continuous image guidance.
The use of contrast agents during fluoroscopic tests/procedures is also common.
Fluoroscopy used to evaluate
GI tract - Video swallowing evaluation, Esophagram, Upper GI Series (UGI), Small bowel follow through (SBFT), Barium enema (BE).
Urinary system - Cystogram, Voiding cystourethrogram (VCUG).
Barium
Contrast agent
Barium is an inert substance that has a high atomic mass (density). When mixed with water and swallowed or infused trans-rectally the substance coats the lumen of the GI tract (esophagus, stomach, and/or intestines). The high atomic weight of the Barium attenuates the X-ray beam thus allowing us to see the coated structures.
Water soluble contrast agent
Certain types can be injected into the vascular system, spinal cord, bile ducts, uterine cavity etc.
They can also be used if bowel perforation is suspected because they will be absorbed by the peritoneum safely. Barium does not get absorbed by the body and if spilled into the abdominal cavity can cause peritonitis.
Water soluble contrast agents when injected via IV can have a nephrotoxic effect on the kidneys. Because of this, those individuals with compromised renal function (elevated BUN creatinine levels) or history of renal failure should not be used.
Allergic reaction to water soluble contrast is also a potential problem, although this is much less of a risk today. Patients who have a known allergy can be pre-treated with Prednisone and/or Benedryl prior to a study to prevent allergic reaction.
Water soluble contrast material is filtered by the kidneys and excreted quickly. This allows for evaluation of the urinary system.
Video Swallow Evaluation
Used to evaluate the swallowing function of the oro-pharynx, hypo-pharynx and cervical esophagus ONLY! The patient ingests varying consistencies of barium laden materials to see if they can masticate properly, form a bolus and thus, swallow effectively and safely.
The test also is used to establish the presence and severity of aspiration during swallowing which can cause pneumonia. If aspiration is present airway protective maneuvers and foods of different consistency can be experimented with to see if they help prevent the aspiration from occurring.
Usually performed with a licensed speech therapist who teaches the patient airway protective maneuvers and suggests changes to the patients diet to aid in swallowing.
Not the same as an esophagram!
Esophagram
The patient ingests Barium at a rapid pace to visualize the entire esophagus.
The study can determine the presence of aspiration, swallowing abnormality, PUD, mass, stricture, obstruction, hiatal hernia, diverticula, perforation and/or gastro-esophageal reflux.
Upper GI Series
(UGI)
Used to evaluate the esophagus and stomach.
Can evaluate everything that an esophagram can plus:
gastric PUD, masses, polyps, inflammation (gastritis), perforation, and/or outlet obstruction.
Small Bowel Follow Through
(SBFT)
Used to evaluate the small bowel for IBD (Crohn's disease), tumor, adhesions, stricture, or obstruction.
The entire upper GI tract (esoph., stomach & small bowel) can be evaluated by ordering a UGI/SBFT study if necessary.
Barium Enema
Contrast is infused trans-rectally to allow for visualization of the colon.
Can be uncomfortable.
Used to identify the presence of colonic polyps/masses, IBD, diverticulosis(itis), perforation, stricture, and/or obstruction.
Most common cause of bowel obstruction is adhesion from previous surgery
Worldwide it’s hernia
Urinary Tests - IVP or IVU
Water soluble contrast is injected into the body via an IV. The contrast is then filtered by the kidneys and evaluation of the renals, ureters and bladder can be made.
Provides information regarding the function of the kidneys also.
Renal - masses, cysts, stones, perforation or OBS.
Ureters - Stones, strictures, perforation or OBS.
Bladder - Stones, masses, perforation, OBS.
Interventional Radiology or Angio
Interventional radiology utilizes fluoroscopy, ultrasound, CAT scan and/or mammographic technologies to perform invasive tests and therapeutic procedures on patients. The procedures performed allow us to limit the recovery time, discomfort and risk to the patient. The procedures are typically much less costly and safer than some related surgical options. The use of image guidance increases safety, accuracy and efficiency.
Special needles, guide-wires, ports, infusion catheters, and drainage tubes are commonly used to perform the necessary interventions.
Interventional Radiology or Angio used for
Guided organ/tissue biopsy
Fluid collection drainage
Abscess drainage
Urinary drainage tube/stent placement
Vascular angiography
Vascular angioplasty, stent placement & embolization
Vascular access device placement (chest/arm ports, PICC lines, dialysis catheter placement, triple lumen etc.)
Hepatic bypass (TIPSS)
Tumor ablation/embolization (liver,uterus etc.)
Vertebroplasty
Myelography, Discography
Therapeutic joint injection and arthrography
V/Q scan
ventilation/perfusion ratio
scan for Pulmonary Embolism
V – Ventilation Image made with radioactive gas or aerosol (xenon 133) inhaled by patient
Q – Perfusion Image made with radioisotope tagged albumin injected via IV
A normal scan rules out presence of PE
A low probability cannot rule out PE but when combined with the absence of DVT it is doubtful that there is a PE
An intermediate probability scan is not helpful. Further evaluation should be considered. Angiography?
A high probability Scan indicates an 85% chance of PE
Hemostasis
1. Vascular Phase
2. Platelet Phase
3. Coagulation Phase
4. Fibrinolytic Phase
Platelets
Smallest formed elements in blood
Promote coagulation in the intrinsic clotting pathway by helping to form a hemostatic plug
Thromobocytopenia
an abnormal decrease in number of platelets
Hypoplastic bone marrow, leukemia, folic acid deficiency
Increased platelet destruction
Thrombocytosis
an abnormal increase in the number of platelets
Hemorrhage, infection, cancers, iron deficiency anemia, inflammatory disease, surgery, pregnancy
Returns to normal after recovery
Bicarbonate
(HCO3-)
Released from the pancreas
Biologic levels are controlled through the kidneys, indicating metabolic control
Bicarbonate itself is an intermediate form of carbonic acid (H2CO3)
Plays a crucial role in the physiologic pH buffering system
Normal HCO3- ranges from 22-26 mmol/L
HCO3->26 is alkalosis
HCO3-<22 is acidosis
Approach to Blood Gases
Step 1 - Look at the pH and determine if it is acidotic, alkalotic, or normal
Acidosis<7.35, Alkalosis>7.45
Step 2 - Look at the pCO2 and determine if it is acidotic, alkalotic, or normal
Remember pCO2 indicates respiratory function
Acidosis>45, Alkalosis<35
Step 3 - Look at the HCO3- and determine if it is acidotic, alkalotic, or normal
Remember HCO3- indicates metabolic function
Acidosis<22, Alkalosis>26
Respiratory Alkalosis
pH>7.45
Caused by loss of CO2 (<35 mmHg)
Shifts the equation to the left as less CO2 is available
Etiologies - Hyperventilation (excessive amounts of deep breathing)
Respiratory Acidosis
pH<7.35
Retaining too much CO2 (>45 mmHg)
Shifts the equation to the right as increased CO2, increases H2CO3, which in turn increases H+
Etiologies - COPD, Drug overdose (narcotics), Hypoventilation
Narcotics depress respiratory system
Metabolic Alkalosis
pH>7.45
Due to loss of acids from the body or the production of bases
Simply put, the loss of too much H+ or the addition of a base, similar to HCO3-, causes metabolic alkalosis
Etiologies - Diuretic abuse, Vomiting
Urine is acidic normally so peeing out too much can lead to loss of H+
Metabolic Acidosis
pH<7.35
Due to loss of bases or production or ingestion of acids
An increase in H+, or a loss of a base lead to metabolic acidosis
Etiologies - Diarrhea, Overexertion
Overexertion leads to insufficient supply of O2 to the muscles which leads to a build up of lactic acid, in excess amounts it exceeds the buffering capacity of the blood (due to anaerobic process)
Loss of water so loss of bicarbonate along with it
MUDPILES:
Methanol (paints, plastics, fuel)
Uremia
Diabetic ketoacidosis
Propylene glycol (food preservative)
Isoniazid (Tb drug)
Lactic acidosis
Ethylene glycol (antifreeze, plastics)
Salicylates (Aspirin)
Obstructive Diseases
Asthma diagnosis & severity
COPD patients - Emphysema, Chronic Bronchitis
Bronchodilator effectiveness
Exercise induced or hypersensitivity to allergen?
Reduced FEV1/FVC
Reduced FEF 25-75%
Reduced PEF
Pink puffer
emphysema
Blue bloater
chronic bronchitic
Restrictive diseases
Cystic fibrosis
Interstitial disease - Sarcoidosis, idiopathic pulmonary fibrosis, silicosis; Work related disease - black lung, asbestosis
Track progression of disease
Normal or increased FEV1/FVC
Normal FEF 25-75%
No change in PEF
Reduced FVC
Volumes decrease instead of flows
TLC
total lung capacity
VC + RV
VC
vital capacity
total volume for gas exchange
full expiration, aids minute volume if they need to cough, secretions
IRV + VT + ERV
RV
residual volume
what’s left after full expiration
IC
inspiratory capacity
IRV + VT
FRC
functional residual capacity
ERV + RV
ERV
expiratory residual volume
forced expiration
IRV
inspiratory reserve volume
what can be inhaled in a deep breath
VT
tidal volume
volume used during resting breathing
Minute volume
Minute volume = resp rate x tidal volume (VT)
Controls CO2 level
FEV1
The forced expiratory volume achieved during the first one-second period
Normal range = >80% predicted
FEV1/FVC
the ratio of volume During the 1st second of expiration in comparison to the total vital capacity
A better predictor of obstruction than comparing FEV1 to predicted value
FEF 25-75%
Forced expiratory flow rate over the middle 50% of the FVC volume.
Signals disorders in smaller bronchi and larger bronchioles because it measures flow at a later point in the maneuver
Otherwise known as maximal mid-expiratory flow
PEF
peak expiratory flow rate
SVC
(Slow Vital Capacity)
Performed using the same maneuvers as a forced vital capacity only modifying the force exerted during expiration.
Used to allow those patients with severe air-trapping to possibly release more of their ERV in order to get a more accurate reading of their true volumes
Air-Trapping
More severe than Hyper-inflation, volume is unable to escape due to collapsing airways.
Hyper-Inflation
Considered less severe than air-trapping, excess volume can usually be exhaled with extended expiratory time and slower flow.
Plethysmography
Method of testing lung volumes
Otherwise known as the 'body box". An airtight, telephone booth style box with a mechanical shutter which can occlude at any phase of respiration.
Based on Boyle’s Law - P1V1=P2V2 when temperature is constant.
This equation allows us to establish patient’s lung volumes due to change in gas pressure or volume after establishing a known set of parameters.
Nitrogen Washout
Based on patient’s ability to cooperate as 100% oxygen is inhaled for several minutes through a 2-way valve (7 minute max). Exhaled gas is measured for nitrogen content after each breath until N2 is <1.5% for 3 breaths.
FRC is calculated from final nitrogen concentration which allows us to establish RV and TLC.
Diffusion Capacity
(DLCO)
Testing the ability of oxygen and carbon dioxide to diffuse across the alveolar membrane.
Involves SVC maneuver followed by fast inspiration and breath hold for ten seconds with slow exhalation to follow.
Carbon Monoxide and helium (trace amounts) are used to perform the test due to increased affinity to hemoglobin.
Methacholine Challenge Test
Used to determine presence & severity of Asthma or reversible airways disease.
Pt given 4 preset incrementing dosages of methacholine followed by spirometry after each dosage.
Dosage set by American Thoracic Society.
Looking for decrease of 20% in FEV1 within the first 3 dosages.
PFT Interpretation
Use spirometry to evaluate for obstructive or restrictive process.
Use Lung volumes to confirm your answer.
Did patient give a good effort?
Are the post bronchodilator treatments effective?
Does diffusion seem to be a problem?
Consider these values along with pt. history, signs and symptoms to determine possible disease states and progression of disease.
Capnometry
Trending Alveolar ventilation & V/Q imbalances caused by pulmonary or Cardio disorders
Used to estimate Physiological dead space
Detect extubation or esophageal intubation
Assess blood flow in CPR
Determine Peep levels
Evaluate airway Obstruction
Incentive Spirometry
Deep breathing by the patient to accomplish hyperinflation evidenced through use of a flow or volume oriented spirometer
The goal is to prevent atelectasis post-operatively
The patient is expected to achieve at least 12 ml/kg to reverse atelectasis
Atelectasis can lead to pneumonia
Peak Flow Meter
Determines the severity of asthma
Checks response to treatment during an acute asthma episode
Monitors progress in treatment of chronic asthma and provides objective information for any possible adjustments in therapy
Detects worsening in lung function and thereby helps avoid a possible serious flare-up in asthma with early intervention
Liver
Largest solid organ in the body
Performs over 500 chemical processes
Produces over 160 different proteins
Makes clotting factors for the blood
Stores & releases sugar as glycogen
Metabolizes (recall CYP 450 isozymes!), detoxifies, synthesizes
Hepatitis
Refers to any swelling, inflammation, or irritation of the liver
More than 100 known causes including:
Viruses, alcohol, enzyme deficiencies, Genetic disorders, licit & illicit drugs, toxins, Hypotension (shock liver/reperfusion)
Viral hepatitis (A,B,C,D,E,G),
Also CMV (Cytomegalovirus); HSV (Herpes Simplex); WNV (West Nile Virus)
Drug-induced hepatitis (acetaminophen)
Alcoholic hepatitis
Autoimmune hepatitis
Ischemic hepatitis
Hepatitis A, B, C Presentation
May include any of the following:
Fever
Malaise; Fatigue
Nausea & Vomiting
Anorexia
Jaundice
Abdominal RUQ Pain
Dark Urine
Routes of Transmission for Hepatitis A, B, C
Hepatitis A --> fecal – oral route
Hepatitis B, C --> serum + blood products; saliva, semen, vaginal secretions
Increased risk in IVDUs, illegal drugs, unsanitary practices, health care workers (unsafe practices)
Hepatitis A
Food, water borne; heat labile
Fecal - oral contamination; contagious
Usually self limited, lasting days to weeks
99% spontaneous recovery, no treatment
Tests:
HAV IgM antibody = acute infection
HAV total antibody (IgM + IgG) = exposure only (could be post-infection or post-vaccination)
Hepatitis B
Blood, semen, saliva, vaginal secretions
Highly contagious; sexually transmitted
90-95% self limited over 6 months
Chronic infection is > 6 months
DNA virus - incorporates into host with chronic infection.
Hepatitis C
Blood borne, not in food or water; not highly sexually transmitted.
Not highly contagious.
20% self-clearing; 80% chronicity
RNA virus - does not incorporate into host.
#1 identified cause of need for liver transplant.
Inflammation of the liver
Inflammation that lasts long enough will create fibrosis
Extreme fibrosis is called cirrhosis.
Cirrhosis can be either compensated or decompensated
Compensated cirrhosis can be subtle (in its presentation)
Decompensated cirrhosis is more obvious
H. pylori
Implicated in diseases of the upper GI Tract including:
chronic active gastritis
gastric ulcer
duodenal ulcer
non-ulcer dyspepsia
gastric adenocarcinoma
MALT Lymphoma (mucoid associated lymphoid tissue)
Pharyngitis
viral
The pathogens:
Rhinovirus and coronavirus most common
Ebstein-Barr virus (EBV) –-> infectious mononucleosis, dx of exclusion
Coxsackie A and herpes virus, the most common cause of ulcerative pharyngitis
HISTORY:
Classic symptoms --> Fever, throat pain, dysphagia
Most likely concurrent URI symptoms of rhinorrhea, cough, hoarseness, conjunctivitis & ulcerative lesions
Insidious, low grade fever, usually lacks exudates
PHYSICAL EXAM:
Non specific viral pharyngitis – unimpressive
Marked erythema typically occurs with adenoviral infection. In contrast, rhinoviral and coronaviral infections are not likely to manifest with severe erythema
Exudates with adenovirus, look for conjunctivitis
Coxsackie – vesicles/ulcerative lesions present on pharynx or posterior soft palate
EBV
(Mononucleosis)
Classic Triad – fever, pharyngitis, adenopathy
History:
Severe sore throat, fatigue/myalgia/malaise, anorexia secondary to pain, fever
Sick contacts? --> transmitted via infected saliva
PE:
White exudates covering erythematous pharynx and tonsils, cervical adenopathy*, possible HSM, Palatal petechiae, Occasionally a maculopapular rash
*Mono presents atypically in adults:
40% inguinal adenopathy
60% cervical adenopathy
Diagnostic studies (blood tests):
Heterophile agglutination test (Monospot)
Lymphocytic predominance (>50% of diff) and >10 % atypical lymphocytes on blood smear
Antibodies to EBV antigens:
Acute phase antibodies - xEA, xIgM VCA
Convalescent antibody - xIgG VCA
Recovered State - xIgG VCA, xEBNA
Bacterial Pharyngitis
Strep pyogenes (group A ß-hemolytic, “GAS”)
Neisseria gonorrhea
Haemophilus influenzae
Corynebacterium diphtheriae
Borrelia vincenti
Mycoplasma
Chlamydia
Signs and symptoms:
Inflammation of the pharynx & lymphoid tissue results in fever, sore throat, malaise, and HA
Absence of viral symptoms
Classic findings for GAS throat include:
High fever
Tonsillar exudates
Anterior cervical adenopathy
Diagnostics:
Throat swab (x2 together!) is performed
Rapid Strep Test
Takes about 10–20 minutes
Positive results are definitive
70-90% sensitive
Negative results should be confirmed with a culture
Gold standard --> culture of swab of tonsils and posterior pharynx
90-99% sensitive
Takes about 24 – 48 hours
More accurate than Rapid Strep Test
Gonococcal Pharyngitis
History consistent with oral GC exposure
No specific PE findings --> Sore throat, difficulty swallowing, fever, tender, swollen lymph nodes in the neck
Recurrent sore throats not responsive to usual Abx’s
Perform throat culture
Diptheria Pharyngitis
SYMPTOMS:
Sore throat, dysphagia, weakness, malaise
SIGNS:
Toxic appearance, fever, tachycardia (out of proportion to fever), pharyngeal erythema
Gray-white tenacious exudate or "membrane" occurs at tonsillar pillars and posterior pharynx; Leaves focal hemorrhagic raw surface when removed
Cervical lymphadenopathy can be significant
"Bull neck"
Influenza
Signs and symptoms:
Often necessary to differentiate influenza from the common cold
Symptoms include high fever (up to 104° F), chills, HA, exhaustion, generalized aches, cough, +/- GI complaints
Patients occasionally report clear nasal congestion, sneezing, and sore throat
Abrupt onset
Diagnosis:
Routinely based on clinical signs & symptoms
PE shows mild pharyngeal erythema, cervical adenopathy, clear nasal discharge
Nasopharyngeal swab or aspirate can be obtained for a rapid antigen test
Chest xray usually normal
Epiglottitis
Most commonly due to H. influenzae
Other organisms include:
S. pneumoniae, Staph aureus, Candida albicans, HSV
3D’s --Drooling, Dysphagia and Distress
difficulty swallowing and breathing, tripoding, muffled voice
DO NOT ATTEMPT THROAT CULTURE
Diagnosis:
Lateral neck x-ray --> shows "thumbprint sign" of narrowed and thickened epiglottis
Epiglottis direct visualization via laryngoscopy
"cherry red" appearing epiglottis
Perform ONLY in OR after airway is secure
Obtain surface cultures of the epiglottis
Blood cultures are positive for causative agent in 90% of cases by some reports
Mantoux Tuberculin Skin Test
PPD - Purified Protein Derivative
Measure the area of induration not the area of erythema
≥ 5 mm, for highest risk group
Immune compromised --> Transplant, HIV, chronic steroid use
Close contact with TB
Abnormal CXR
≥ 10 mm, ‘other’ risk factors
IVDU, homeless, hospital/prison/shelter
Recent immigrant
DM, malignancy, malnutrition, renal failure
≥ 15 mm, no known risk factors
Pneumonia
Clinical Manifestations:
Cough
Fever
Chest discomfort or pain
Dyspnea
Sputum production
Diagnostics:
CXR - The gold standard – ideally PA and lateral
Consolidation? Atelectasis? Pleural effusion?
Bronchoscopy with biopsy/lavage
PCP, TB
Percutaneous needle aspiration
5% risk of pneumothorax
Thoracentesis
Community Acquired Pneumonia
Viral - Influenza, RSV, Adenovirus, Parainfluenza
Atypical Pneumonias - Legionella (3-30%), Mycoplasma (5-35%)
Pneumocystis (PCP)
Bacterial - Pneumococcal (30-75%), Other Streps, A&B, S.aureus (3-10%), H.influenzae (6-12%), Klebsiella pneumoniae, Anaerobes
Pneumococcal Pneumonia
History:
Most common cause of CAP
Elderly or chronically ill pt
Alcoholism, smoking, nursing home, college dorm
Gram stain:
Rust colored sputum
Polys with gram + lancet shaped cocci in singles and pairs
CXR:
Stays within anatomical borders – lobar
CXR lags behind clinical picture
Sputum Culture - Usually positive for S.pneumo
Blood Culture - 20-30% positive
CBC:
Leukocytosis
15-30,000 WBC
Left shift common
Staphlococcal Pneumonia
History:
CAP during flu outbreak, post URI, IV drug use, Pleuritic CP
CXR:
Patchy infiltrates involving multiple areas of lung
Gram stain:
many PMNs & gram + cocci in clusters
CBC:
Elevated leukocyte count
Culture:
May be positive
Haemophilus influenzae
History:
Smokers/COPD, nursing home
Children < 2yo
CXR:
Broncho/lobar
Polys and gram - bacilli
Sputum culture:
70 % culture & gram stain pos.
Blood culture:
20-80% blood culture positive
Klebsiella pneumonia
History:
Elderly, ETOH/DM/COPD, fever, rigors, sputum +/-blood
CXR:
Upper lobe abscess, pleural effusion, +/- interlobar fissure
Gram stain:
Polys and gram - rods
Legionella pneumonia
History:
Common source outbreaks, contaminated water from cooling and ventilation
CXR:
dense consolidation
50% have pleural effusion
Gram stain:
Weakly staining gram negative bacilli
Fluorescent Ab staining
CBC:
Leukocytosis with left shift
Urine antigen:
Highly sensitive and specific
(Hotel across from SUNY Albany)
Mycoplasma Pneumonia
History:
CAP- close quarters, 50% college students, military
CXR:
Diffuse patchy infiltrates involving entire lung
Cold Agglutinins:
Positive
CBC:
Slight leukocytosis
Gram stain:
Shows no bacteria
EIA (Enzyme Immunoassays):
Serology for diagnosis
Cold Agglutinins
done to check for conditions that cause the body to make certain types of antibodies called cold agglutinins. Cold agglutinins are normally made by the immune system in response to infection. They cause red blood cells to clump together (agglutinate) at low temperatures.
Viral Pneumonia
History:
CAP- flu outbreaks
CXR:
Patchy infiltrates, peribronchial thickening, pleural effusion
Rapid antigen tests can detect influenza, RSV, parainfluenza, and other viruses
CBC:
Leukopenia may be notable
Lymphocytosis common
Hospital Acquired Pneumonia
Leading cause of mortality from nosocomial infection
Risk- Obtundation with impaired cough/gag reflex
Common causes:
P aerugionsa, Klebsiella, E coli, S pneumoniae, H influenzae
Work-up:
purulent sputum ⇨ culture
Fever, chills, rigors ⇨ blood culture
CBC
CXR
+/- ABG
Croup
(Acute laryngotracheobronchitis)
Infection of the upper airways—larynx, trachea, upper levels of the bronchial tree
Obstruction of airways by edema
Etiology:
Parainfluenza viruses (75%), Adenovirus, respiratory syncytial virus (RSV), Mycoplasma pneumoniae (~3–4% of cases)
Most cases in the autumn and early winter
Peak age incidence - 3 months to 5 years old
WBC count -- normal to slightly elevated
Chest x-ray can be normal, however…
40–50% of children, anteroposterior soft-tissue x-rays show subglottic narrowing, -- classic "steeple" sign of croup
TNTC
Too numerous to count
Lab medicine
A popular abbreviation for a 'lawn' of bacteria on a culture plate that may be seen in UTIs - confluent growth is equal to ±105 colonies