Respiratory acidosis: Difference between revisions
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''see also [[hypercapnia]] | |||
==Background== | ==Background== | ||
*acidemia = pH < 7.38 | *[[acidemia]] = pH < 7.38 | ||
*respiratory acidosis = pCO2 > 42 | *respiratory acidosis = pCO2 > 42 | ||
*Acute respiratory acidosis: Change in pH = 0.008 X (40 - PaCO2) | *Acute respiratory acidosis: Change in pH = 0.008 X (40 - PaCO2) | ||
vs. | *vs. chronic respiratory acidosis: Change in pH = 0.003 X (40 - PaCO2) | ||
*determine if another primary acid/base disturbance is occurring | *determine if another primary acid/base disturbance is occurring | ||
**calculate AG | **calculate AG | ||
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===Etiology=== | ===Etiology=== | ||
Hypoventilation - acute vs chronic | *Hypoventilation - acute vs chronic | ||
==Differential Diagnosis== | ==Differential Diagnosis== | ||
*[[COPD]] | *[[COPD]] | ||
*Drugs ([[ | *Drugs (e.g. [[opioid overdose]]) | ||
*Chest wall disease | *Chest wall disease | ||
*Pleural disease | *Pleural disease | ||
*Trauma | *[[Trauma]] | ||
==Evaluation== | ==Evaluation== | ||
Revision as of 16:40, 29 September 2019
see also hypercapnia
Background
- acidemia = pH < 7.38
- respiratory acidosis = pCO2 > 42
- Acute respiratory acidosis: Change in pH = 0.008 X (40 - PaCO2)
- vs. chronic respiratory acidosis: Change in pH = 0.003 X (40 - PaCO2)
- determine if another primary acid/base disturbance is occurring
- calculate AG
- if HCO3 < 24 + (pCO2-40)/10 x 3(+/-1) then there is a superimposed primary metabolic acidosis
- for every 10mm increase in pCO2 >40, HCO3expected increases by 2-4mEq (2 if acute/limited time for metabolic compensation, 4 if chronic i.e. COPD)
- if HCO3 > 24 + (pCO2-40)/10 x 3(+/-1) then suspect primary metabolic alkalosis
Etiology
- Hypoventilation - acute vs chronic
Differential Diagnosis
- COPD
- Drugs (e.g. opioid overdose)
- Chest wall disease
- Pleural disease
- Trauma
Evaluation
Management
Improve alveolar ventilation
- Bronchodilators
- CPAP
- Intubation (esp of pH < 7.25)
- Do not reduce pH too quickly (>5Hg/h)
- Can lead to abrupt Hypocalcemia/Hypokalemia
- Do not reduce pH too quickly (>5Hg/h)