Airway and breathing

Patients may be rousable, but still have respiratory depression. Monitor the patient with objective measures of respiratory function that can be done while the patient is asleep. The best methods are:

• oxygen saturation on room air (continuous)
• end-tidal partial pressure of carbon dioxide and respiratory rate (continuous)
• blood gas analysis (required if the patient is not maintaining adequate oxygenation on room air)—partial pressure of arterial carbon dioxide (PaCO₂) is the most reliable measure of hypoventilation.

Patients able to maintain oxygen saturation greater than 92% on room air have adequate ventilation. Falling oxygen saturation on room air may be the first indicator of hypoventilation. If the oxygen saturation drops, manage hypoventilation with naloxone. If there is no response to naloxone, intubate and ventilate the patient.

Manage aspiration pneumonitis and noncardiogenic pulmonary oedema with oxygen therapy and ventilatory support as needed.