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What does pH measure and what is the normal range of blood pH?
- Measure of H+ ion concentration
- Normal range for pH is 7.35 to 7.45
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Describe the acid/base regulator Buffers
- act chemically to neutralize acids or change strong acids to weak acids
- Primary regulators
- React immediately
- Cannot maintain pH without adequate respiratory and renal function
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Describe the respiratory acid/base regulator
- eliminates CO2
- medulla in the brainstem controls the rate of excretion of CO2
- Responds within minutes/hours
- Increased respirations lead to increased CO2 elimination and decreased CO2 in blood (less carbonic acid and less H+)
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Describe the Renal acid/base regulator
- eliminate H+ and reabsorb HCO3−
- Reabsorption and secretion of electrolytes (e.g., Na+, Cl−)
- Slower to respond - hours to days
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Respiratory Alkalosis presentation, cause, and regulatory action
- pCO2 is low [< 35 mm Hg]
- pH is high [>7.4]
- O2 is normal
- cause = hyperventilation
- If condition persists, kidneys will compensate by excreting HCO3
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Respiratory Alkalosis S/Sx
- Pts. Will hyperventilate to compensate for hypoxemia
- anxiety, apprehension, restlessness
- lightheadedness, circumoral numbness
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Respiratory Alkalosis Interventions
- Directed at underlying cause
- Anxiety, hyperventilation, etc.
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Respiratory Acidosis presentation, cause, and regulatory action
- pCO2 is high [>45]
- pH is low
- In Chronic Respiratory Acidosis [PCO2 >50]
- cause = hypoventilation
- kidneys will compensate by retaining HCO3, given time
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Respiratory Acidosis S/Sx
- depth of ventilation-chest not rising adequately
- restlessness, apprehension, disorientation [R/T hypoxemia]
- lethargy “CO2 narcosis”
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Respiratory Acidosis Interventions
- Improve ventilation: elevate HOB, head tilt, etc.
- Check oxygenation: PO2/Sat from ABG or pulse oximetry
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Metabolic Acidosis presentation
- base bicarbonate deficit
- HCO3 is low [ < 22-26 mEq/L]
- pH is low
- Too much acid: diabetic ketoacidosis, Lactic acidosis/ shock, end stage renal disease
- Too little HCO3: Loss in severe diharrea, GI fistula
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Metabolic Acidosis S/Sx
- rapid, deep breathing [compensatory mechanism - “blowing off acid”]
- drowsiness, disorientation
- hyperkalemia
- cardiac dysrhythmia
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Metabolic Alkalosis presentation and causes
- base bicarbonate excess
- HCO3 is high [> 26 mEq /L]
- pH is high
- Too much base: excessive antacid use
- Too little acid: severe vomiting, gastric suction [large amounts], high-dose diuretic therapy
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Mixed Acid Base Disorder
- when two or more disorders are present at the same time
- Respiratory acidosis combined with metabolic alkalosis may result in a near-normal pH
- respiratory acidosis combined with metabolic acidosis causes a greater decrease in pH than either disorder alone
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Normal serum pH range
7.34-7.45
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Normal Bircarbonate (HCO3) range
22-26
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*pH 7.58 *PaCO2: 35mmHg *PaO2: 75mmHg *HCO3: 50mEq/L
a)Respiratory acidosis
b)Respiratory alkalosis
c)Metabolic acidosis
d)Metabolic alkalosis
d) Metabolic alkalosis
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*pH 7.60 *PaCO2: 30mmHg *PaO2: 60mmHg *HCO3: 22mEq/L
a)Respiratory acidosis
b)Respiratory alkalosis
c)Metabolic acidosis
d)Metabolic alkalosis
b) Respiratory alkalosis
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*pH 7.18 *PaCO2: 38mmHg *PaO2: 70mmHg *HCO3: 15mEq/L
a)Respiratory acidosis
b)Respiratory alkalosis
c)Metabolic acidosis
d)Metabolic alkalosis
c) Metabolic acidosis
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*pH 7.20 *PaCO2: 58mmHg *PaO2: 59mmHg *HCO3: 24mEq/L
a)Respiratory acidosis
b)Respiratory alkalosis
c)Metabolic acidosis
d)Metabolic alkalosis
a) Respiratory acidosis
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