Hypercapnia: Difference between revisions
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Revision as of 01:13, 24 July 2017
Background
- PaCO2 >45
- Exclusively caused by alveolar hypoventilation
- Results from decrease in respiratory rate, tidal volume, or increase in dead space
Clinical Features
- Headache, confusion, lethargy, seizure, coma
- Extreme hypercapnia (acute elevation >100) can result in cardiovascular collapse
Differential Diagnosis
- Depressed central respiratory drive
- Structural CNS disease: brainstem lesions
- Drug depression of respiratory center: opioids, sedatives, anesthetics
- Endogenous toxins: tetanus
- Thoracic cage disorders
- Kyphoscoliosis
- Morbid obesity
- Neuromuscular impairment
- Neuromuscular disease: myasthenia gravis, Guillain-Barré
- Neuromuscular toxin: organophosphate poisoning, botulism
- Intrinsic lung disease associated with increased dead space
- Upper airway obstruction
Evaluation
- ABG
- HCO3 increases 1 mEq/L for each 10mmHg increase in PaCO2 (acute)
- HCO3 increasess 3.5 mEq/L for each 10mmHg increase in PaCO2 (chronic)
Management
- Increase minute ventilation (rate and/or tidal volume)