is a factor that influences the DO2. graphically depicts the relationship between the oxygen content or Hb saturation.
Oxyhemoglobin Dissociation Curve (ODC)
is an increase in cardiac output. Patients with compromised reserve systems who are not capable of increasing cardiac output or who cannot tolerate a further reduction in tissue oxygenatoion are at great risk for hypoxia if they have a?
significantly left shifted ODC
In most patients, __________ is advantageous for oxgen transport except under the most extreme hypoxemic conditions.
A rightward shift of the ODC
is used universally in the ICU as a measurment of pulmonary gas exchange, but is not specific or sensitive enough to be used exclusivley in the estimation of oxygen transport.
is an excelent value to follow to identify which therapies are effective to manage a pulmonary gas exchange problem. that is not associated with other complications.
There are three reasons that the PaO2 should not be relied on in assessing systemic oxygen transport.
gas tension not gas delivered, partial pressure available not used, PaO2 could fall due to an increase in intrapulmonary shunt
PaO2 should be kept within a range of?
PaO2 values above ______ are usually unnecessary except in situations such as CO poisoning and during periods of severe anemia or cardiaogenic shock.
PaO2 greater than ______ has been shown to cause a reduction of blood flow to both kidneys and the brain, probably as a reult of vasoconstriction.
125 mm Hg
This has been commonly used as an indication of gas exchange efficiece. Its major limitation is that it changes with adjustments in FiO2.
this ratio is more useful index of pulmonary gas exchange than the P(A-a)O2 because it remains more stable with changes in FiO2.
Arterial/Alveolar tension ratio
this is similar to the arterial/alveoal tension ratio, but it is easier to use because it does not require calculation of PAO2.
A PaO2/FiO2 ratio of 200 and 300 is assosiated with?
a PaO2/FiO2 ratio less than 200 is associated with?
this was initially developed as an index of ventilatory-oxygenation support for a human surfactant trial and then adapted as a prognostic index for morebidity and mortality for infants requiring extracorporeal membrane oxygenation (ECMO).
Oxygen Index (OI)
Infants with sever respiratory failure who are canidates for ECMO often have OI values greater than?
a method for measuring cardiac output using oxygen consumption and the oxygen content difference between arterial and venous blood
is used often in the ICU because of its convenience more than its accuracy.
This will stay constant as long as the delivered Oxygen is greater than a critical threshold of approximately 8-10ml/min/kg in anesthetized humans.
Paitents ARDS and sepsis have an elevated VO2. it is linear DO2 up to _______?
has been shown to be an excellent predictor of survival in patients with trauma and shock and is helpful in dtermining the adequacy of resusitation.
VO2 values of _______ of the normal range following trauma or shock are associated with a better progonosis and have been identified as appropriate theraputic goals for the high-risk surgical patient.
VO2 less than _____ may be the result of decreased oxygen availability, as with low cardiac output or oxygen content, or with decreased use, as in hypothermia.
is a measure of the partial pressure of oxygen in mixed venous blood and is an indication of oxygen usage by the entire body.
Mixed venous oxygen tension (PVO2)
normal range of PVO2
inadequate cardiac output, Anemia, significant hypoxia, "affinity" hoypoxia can cause?
a PVO2 less than _____ usually associated with lactic acidosis
Poor sampling technique, left-to-right shunt, septic shock, increased cardiac output, cyanide poisoning can cause what?
organs with poor perfusion make minimal contribution to venous return; therefore PVO2 may remain in the __________even though an oxygen deficit exists
VO2 is high for the heart and the brain, PVO2 of these organs is extreamly critical. a fall in perfusion would require a compensatory mechanism to ____________.
maintian blood and oxygen flow to those organs
is the most important factor in the assessment of the cardiovascular system's ability to meet the body's metabolic demands.
adequacy of perfusion
the amount of blood pumped out of the left ventricle in a minute.
Cardiac output (CO)
it is the product of heart rate (HR) and stroke volume (SV).
is the volume of blood ejected by the ventricle by a single heart beat.
Stroke Volume (SV) equal for both ventricles
Normal SV is?
The average CO for men and women of all ages is approximately?
5L/min at rest (4-8L/min)
The normal heart is capable of pumping?
The volume of blood returning to the right atrium is known as?
when oxygen is low and hydrogen ions and carbon dioxide levels are increased at the tissue level, this occurs?
the greater the vasodialtion, the more?
blood flow to the area
Acts as a resevoir of blood to maintain flow to the vital organs when blood volume is lost. Approximately 64% of the total blood volume is normally in this.
If blood flow is too low, the CNS will compensate causing vasocontriction and blood flow to certain organs is?
The CNS will reduce blood flow to the liver, kidneys, and other body areas to maintain blood flow to where?
heart and brain
May be used to describe flow output. is CO divided by body surface area and is reported as liters per minute per square meter.
Cardiac Index (CI)
is calculated by using the PT's weight and height and nomogram.
A normal restinf CI for patiens of all ages is?
is a measurment of energy the heart uses to eject blood against the aortic or pulmonary presures and increases as the end-diastolic ventricular size increases.
Measures the work per minute per square meter for each ventricle.
Cardiac work Index
is a measure of myocardial work per contraction. Is the prduct of the SV times the pressure across the vascular bed.
Ventricular Stroke Work
end-diastolic ventricular size can be assessed by this. it is defined as the amount of blood in the ventricle at the end of filling ( diastole)
Most commonn indirect method of measuring the end-diastolic ventricular size is the measurement of this?
represents the percentage of the end-diastolic volume that is ejected with each beat.
Ejection fraction (EF)
CO may decrease by _____ before a significant drop in arterial blood pressure occurs.
The third primary factory determining CO?
Is a measure of myocardial contraction strength.
Change in the initial muscle length caused by stretch of the cardiac muscle and change in contractility or inotropic state of the heart at any given amoun t of muscle stretch have major influences on?
This along with release of norepinephrine and other circulating catecholamines results in an increase in the strength and the rate of cardiac contraction: fight or flight responce.
Sympathetic Nerve Stimulation
are medications that affect the strength of contraction.
Increases the force and velocity of contraction and myocardial oxygen consumption.
Possitive inotropic drugs
Calcium, digitalis, epinephrine,norepinephrine, dopamine, dobutamine, amrinone, isoproterenol, and caffine are what kinds of drugs?
Possitive inotropic drugs
Decrease the strength of contraction but may also decrease the myocardial oxygen demand.
negative inotropic effect
Beta blockersm berbituates, and many antiarrhythmic agents such as procainamide and quinidine are all what kind of drugs?
Negative inotropis drugs
Physiologic depresants of cardiac contractility include?
hypoxia, hypercapnia, and acidosis
Plays an important role in the assessment and treatment of critically ill patients.
The pressure measured at the tip of the pulmonary artery catheter when the balloon is inflated; an estimate of the left ventrical pressure
PAWP ( Pulmonary Arterial Wedge Pressure)
Monitors do not always ________. theraputic decicion making based on numbers alone is never appropriate and can be dangerous, even deadly.
"Tell the truth"
Placed in a patient that has significant hemodynamic instability or a patient who will require frequent blood draws.
Two arterial pressure catheter sizes are in common use, and selection is determined by?
planned insertion site.
is ideal for use in radial and otehr small arteries but is not adequate for femoral or other large arteries.
Is ideal for femoral arteries.
The catheter is usually placed in:
radial, ulnar, brachial, axillary, or femoral artery
this artery is preferred because this site is readily accessible and usually has adequate collateral circulation. Easy to monitor and provides a stable site for blood withdrawl.
This artery provides pressure measurments that are less affected by peripheral vasoconstriction, but significant leakage of blood into the surrounding tissue can occur without dtection.
This technique is used for most arterial catheter insertions.
This involves using a needele to penetrate he artery, sft tip guidewire threaded through the needle in to artery, needle then rmoved leaving a guidewire, and catheter advanced over the guide wire.
Should have a clear upstroke on the left, with a dicrotic notch representing aortic valve closure on the downstroke to the right
Arterial pressure waveform
The dicrotic notch disapears in some PT's when the systolic pressure drops below?
Arterial pressure waves take on a many different configurations in PT's in?
the ;eft side of the pressure wave may become straight and even pointed on the top when there is an increase in?
Respiratory variation in the arterial pressure waveform normally goes unoticed beceasue arterial pressure is so high relative to the magnitude of usual?
respiratory pressure changes.
The sensitivity of the monitor usually is set so that the screen covers a pressure range of?
Normal arterial pressure in the adult is approximately?