Acid-base balance problems
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Normal Arterial Blood Gas |
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pH |
7.35 – 7.45 |
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PaO2 |
70-100 mm Hg |
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PaCO2 |
35 – 45 mm Hg |
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HCO3 |
22 – 26 mEq/L |
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Base excess |
-2 to 2 mEq/L |
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SaO2 |
93 – 98% |
Alkalosis or alkalemia – arterial blood pH rises above 7.45
Acidosis or academia – arterial pH drops below 7.35 (physiologic acidosis)
ACID-BASE BALANCE PROBLEMS
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Respiratory acidosis - decreased pH, increased PCO2 - resulted from failure of the Respiratory System to balance pH - Most common cause of acid-base imbalance
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Causes
Respiratory depression Airway obstruction (COPDs, etc) Inadequate chest expansion Pneumonia, Cystic Fibrosis, Emphysema Neuromuscular diseases
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Signs and Symptoms:
Hypoventilation Hypotension Warm, flushed skin with vasodilation Drowsiness, coma
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Management:
Low flow O2 Clear respiratory tract of mucus Liquefy secretions If severe: mechanical ventilation
Antibiotics for respiratory infections, Bronchodilators, mucomyst
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Respiratory Alkalosis - increased pH, decreased PCO2 common result of hyperventilation
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Causes
Hyperventilation from fear, anxiety, hypoxemia, pain
Excessive mechanical ventilation Early ARDS Salicylate intoxication
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Signs and Symptoms:
Rapid, shallow breathing Chest tightness, palpitations Dizziness, lightheadedness Circumoral numbness, tingling Anxiety, tetany, panic |
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Management:
Rebreathe CO2 using paper bag, Cupped hands, rebreather mask Assist patient to breathe slowly Protect from injury
Anti-anxiety medications as needed |
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Metabolic acidosis - decreased pH, decreased HCO3 - 2nd most common cause of acid-base imbalance |
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Causes
Starvation, malnutrition diarrhea Ketoacidosis Trauma, shock Severe infection, fever Salicylate intoxication Hyperkalemia
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Signs and Symptoms:
Deep, rapid respirations Cold, clammy skin Drowsiness, coma Hypotension
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Management:
Treat underlying problem (IV & insulin in ketoacidosis, etc) Monitor electrolytes, esp. K
Sodium bicarbonate IV
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Metabolic Alkalosis - increased pH, increased HCO3
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Causes Excessive vomiting Too much antacids Hypokalemia Constipation, in which excessive bicarbonate is reabsorbed
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Signs and Symptoms:
Hypoventilation Irritability, nervousness Tremors, tetany Seizures
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Management:
Assess for hypoK, hypoCa (due to CA binding to albumin) Teach proper use of antacids
K supplements if hypokalemic Acetazolamide (Diamox) to increase renal HCO3 excretion + H20
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