[FONT='palatino linotype']Respiratory acidosis is defined as a pH less than 7.35 with a PaCO2 greater than 45 mm Hg. Acidosis is caused by an accumulation of CO2 which combines with water in the body to produce carbonic acid, thus, lowering the pH of the blood. Any condition that results in hypoventilation can cause respiratory acidosis. These conditions include:
- Central nervous system depression related to head injury
- Central nervous system depression related to medications such as narcotics, sedatives, or anesthesia.
- Impaired respiratory muscle function related to spinal cord injury, neuromuscular diseases, or neuromuscular blocking drugs
- Pulmonary disorders such as atelectasis, pneumonia, pneumothorax, pulmonary edema, or bronchial obstruction
- Massive pulmonary embolus
- Hypoventilation due to pain, chest wall injury/deformity, or abdominal distention
The signs and symptoms of respiratory acidosis are centered within the pulmonary, nervous, and cardiovascular systems. Pulmonary symptoms include dyspnea, respiratory distress, and/or shallow respirations. Nervous system manifestations include headache, restlessness, and confusion. If CO2 levels become extremely high, drowsiness and unresponsiveness may be noted. Cardiovascular symptoms include tachycardia and dysrhythmias.
Increasing ventilation will correct respiratory acidosis. The method for achieving this will vary with the cause of hypoventilation. If the patient is unstable, manual ventilation with a bag- valve-mask (BVM) is indicated until the underlying problem can be addressed. After stabilization, rapidly resolvable causes are addressed immediately. Causes that can be treated rapidly include pneumothorax, pain, and CNS depression related to medications. If the cause cannot be readily resolved, the patient may require mechanical ventilation while treatment is rendered. Although patients with hypoventilation often require supplemental oxygen, it is important to remember that oxygen alone will not correct the problem.
Taken from Interpretation of ABGs by Orlando Regional Medical Center.