NS2P2. Mod 1. Lect 6. Acids & Bases

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NS2P2. Mod 1. Lect 6. Acids & Bases
2016-01-06 20:24:20
Acids Bases NS2P2 NS2 Michelle

Acids & Bases
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  1. **Review 
    How is pH maintained?
    Normal range?
    Higher pH means?
    =>Plasma pH is an indicator of the concentration of H+ ions

    -Increasesd H+ ions means ACID.

    =>Normal arterial pH range is 7.35-7.45

    • Higher pH (less H+) = alkalosis
    • Lower pH (more H+) = acidosis

    =>The metabolic processes constantly produce acids that must be either neutralized or excreted, there's three ways that this happens.

    • ph is maintained by homeostatic mechanisms:
    • Buffer systems: very fast
    • Respiratory system: kicks in within mins to hours
    • Renal system: kicks in within 2-3 days.

    Acids: vinegar, stomach acid

    Alkaline: baking soda, ammonia, draino
  2. **Chemical Buffer Systems
    carbonic acid to 20 Base Bicarbonates. This is normal in body.

    Maintain the normal 20:1 ratio of bicarbonate: carbonic acid and pH

    -more effective with buffering an acid load than neutralizing excess of base.

    • -react immedately
    • Work to change strong acids into weaker acids or to bind acids to minimize/neutralize effects Carbonic acid

    • - bicarbonate, monohydrogen
    • -dihyodrogen phosphate, intracellular and plasma proteins, and Hgb buffers

    Cannot work without adequate functioning renal and respiratory systems.
  3. **Renal System 
    -In acidosis vs alkalosis?
    • Regulates bicarbonate level in ECF (HCO3)
    • Normal range for bicarb is 22-26 mEq/L

    In acidosis, kidneys conserve bicarb and excrete H+ to buffer blood.

    In alkalosis, kidneys retain H+ (the acids) and excrete bicarb (get rid of base)

    • Renal compensation is relatively slow
    • -just balancing the system by letting go and keeping.

    • -can be maintained indefinitely. Urine pH around 6.
    • Can range from 4-8 in this compensation
    • Begins to buffer in 24 hours, takes 2-3 days to reach this max.

    If renal function is compromised , the body can no longer buffer ):
  4. **Respiratory System 
    -controlled by?
    -brainstem control to CO2 LEVELS.

    =>Controls PaCO2 and thus carbonic acid content of ECF

    NORMAL range for PaCO2 is 35-45 mm Hg

    In acidosis, ventilation increases to blow off CO2 (acid) to get rid of it.In alkalosis, ventilation decreases (HYPOventillation) to retain CO2

    -reacts within minutes, and reaches max effectiveness within hours.

    => the lungs will help maintain normal CO2 in the water, the amount of CO2 is in blood is directly related to Carbonic acid concentration and subsequently H+ ion concentration.
  5. **Acid-Base Imbalance
    Occurs when the ratio of 20:1(base: acid) is altered; Classified as respiratory or metabolic--symptom of underlying problem, must fix problem to balance.

    Respiratory: imbalance of carbonic acid

    Metabolic: imbalance of base bicarbonate

    Imbalance may be acute or chronic

    => AlKalosis: Kicks the pH up (greater than 7.4) and AciDosis brings it Down (less than 7.4)
  6. **Respiratory Acidosis (carbonic acid excess) 
    -Excess of Carbonic acid.

    • =>Occurs w/ hypoventilation and CO2 retention
    • Results in build-up of carbon dioxide
    • Carbonic acid dissociates , liberating hydrogen ions (so ph goes down)pH decreases

    • =>Causes
    • COPD: cause
    • Sedative/narcotic overdose: lowers RR
    • Severe pneumonia, atelectasis: not exchanging oxygen for CO2
    • Respiratory muscle weakness: weak resp

    -If something wrong with resp, then kidneys will compensate by conserve bicarbs and secrete H+ ions into urine (occurs within 24 hours)
  7. **Respiratory Alkalosis (carbonic acid deficit)
    -other causes
    • Occurs w/ hyperventilation and CO2 deficit
    • Primary cause is hypoxemia (decreased O2 in blood)

    • =>Other causes
    • Anxiety: deeep breathing out.
    • CNS disorders
    • Mechanical overventilation
    • -Agressive hypoxemia needed to reverse this.
  8. **Metabolic Acidosis (base bicarbonate deficit)
    • =>Occurs w/ bicarbonate deficit
    • Caused by build-up of acid other than carbonic acid (lactic acid, ketoacid)
    • Caused when bicarbonate is lost from body systems (diarrhea)

    • =>Either secondary to acid accumulation or actual bicarbonate loss
    • DKA
    • Shock
    • Renal failure
    • Severe diarrhea

    -Resp will compensate: by CO2 isolation, get rid of extra acid by increasing RR.

    -Kidneys try to excrete additional acid.
  9. **Metabolic Alkalosis
    • =>Occurs w/ bicarbonate excess
    • Occurs with loss of acid (prolonged vomiting, gastric suction)
    • Occurs with gain in bicarbonate (ingesting baking soda)
    • -more due to loss of acid in body
    • -fasting deficit

    • =>Either secondary to loss of acid or gain in bicarbonate
    • Prolonged vomiting or suctioning
    • Diuretic therapy
    • Potassium deficit
    • Excessive intake
  10. **Acid Base Disorders

    Metabolic Acidosis:
    Metabolic alkalosis:
    Resp Acid:
    Resp Alkalosis: High pH, Low CO2
    Metabolic Acidosis: Low pH, Low BiCarb

    Metabolic alkalosis: Low ph, High Bicarb

    Resp Acid: Low ph, High CO2

    Resp Alkalosis: High pH, Low CO2
  11. **ABGs 
    -alan's test
    Used to determine type of acid-base imbalance as well as oxygenation; blood taken out of arterial line, venous blood will alter results (not oxygenated

    • -Alan's Test: block both sides of the circulation
    • -assess circulation and cap refill after blood draw

    • =>Normal results
    • pH 7.35-7.45
    • PaCO2 35-45 mmHgH
    • CO3- 22-26 mEq/L
    • PaO2 80-100 mmHg
    • SaO2 >95%
  12. **Acid-Base Imbalances
    1. Respiratory Acidosis pH <7.35, PaCO2 >45

    2. Respiratory Alkalosis: pH >7.45, PaCO2 <35

    3. Metabolic Acidosis: pH <7.35, bicarb <22

    4. Metabolic Alkalosis: pH >7.45, bicarb >26
  13. *Assess for Causative Factors
    • =>Health history
    • Diabetes, COPD, GI disorders, renal failure
    • Medications (OTC, Rx, and recreational drugs)
    • Surgeries
    • Acute illnesses

    =>Respiratory assessment

    =>GI and GU assessment
  14. **Clinical Manifestations
    No specific physical assessment to assess acid-base imbalance.

    • =>Abnormal findings among major body systems:
    • Neurologic
    • Cardiovascular
    • Gastrointestinal
    • Neuromuscular
    • Respiratory
  15. **ABG Interpretation
    Is it an acidosis or alkalosis?

    Is it respiratory or metabolic?

    Is compensation occurring?
  16. ABG Interpretation
    1. Consider the pH: is it normal, high, or low?

    2. Determine if the imbalance is RESPIRATORY or METABOLIC by evaluating the PaCO2 and HCO3

    • -Example:
    • pH >7.45 (alkalosis)
    • If PaCO2 <35: respiratory alkalosis
    • If HCO3- >26: metabolic alkalosis
  17. **Compensation: Third step of ABG interpretation
    is to determine if compensation is occurring

    Lungs and kidneys compensate to return pH to normal

    Compensation may be partial or complete

    So if pH normal but other values abnormal: compensated acid-base imbalance
  18. Clinical Manifestations of Respiratory Acidosis
    Drowsiness,confusion, dizziness, headache, coma

    Cardio: low BP, Ventricular fib (related to hyperkalemia from compansation), warm flushed skin (due to peripheral vasoldilation)

    GI: no changes

    Neuro: seizures

    Respiratory: Hypoventilation with hypoxia (lungs are unable to compensate when there is a respratory problem)
  19. Clinical Manifestations of Metabolic Acidosis
    Drosiness, confusion, dizziness, headaceh, coma

    Cardio: low BP, dysrhythmia (r/t hyperkalemia from compensation), warm flushed skin (r/t peripheral vasodilation)

    GI: N/v, diarrhea, abdominal pain

    Resp: Deep, rapid respirations (compensatory action by the lungs)
  20. Clinical Manifestations of Resp Alkalosis
    Neuro: dizzziness, light headedness, confusion, headace

    Cardio: tachy, dysrhythmias (r/t hypokalemia from compensation),

    GI: n/v, epigastric pain

    Neuro: tetany, numbness, tingling of extermities, Hyperreflexia seizures

    Resp: Hyperventilation (lungs are unable to compensate when there is a respiratory problem)
  21. Clinical Mnifestations of Alkalosis:
    Neuro: dizzziness, light headedness, confusion, headace

    Cardio: tachy, dysrhythmias (r/t hypokalemia from compensation),

    GI: n/v, epigastric pain

    Neuro: tetany, numbness, tingling of fingers and toes, muscle cramps, hypertonic muscles, seizures

    Resp: Hypoventilation (compensatory action by the lungs)