Postoperative Complications - Respiratory:
1. Airway obstruction
Definition: Blockage of any part of the airway.
Etiology: The most common cause of post-operative airway obstruction is upper airway obstruction. This is secondary to residual muscle relaxant (causing the tongue to fall backwards) or inadequate recovery from anesthetic agents. Other causes include trauma leading to edema, neck hematoma, pooled secretions, laryngospasm, laryngeal nerve injury.
Clinical picture: Desaturation, snoring, paradoxical breathing.
Treatment: Head tilt, chin lift, jaw thrust. Consider insertion of oral or nasal airway if the patient is obtunded. Provide supplemental oxygen.
2. Hypoxia
Definition: Reduced oxygen content in the arterial blood (SaO2 < 90%, PaO2 < 60 mmHg or a fall > 5% in SaO2)
Etiology:
- Hypoxic gas mixture: ensure patient is actually receiving supplemental oxygen
- Hypoventilation: low tidal volumes secondary to surgical site pain or residual neuromuscular blockade, airway obstruction
- V/Q mismatch: pulmonary edema, aspiration, PE, low cardiac output
- Others: methemoglobinemia, malignant hyperthermia (MH)
Clinical picture: Cyanosis, drop in saturations, PaO2 < 60mmHg on ABG
Treatment: Supplemental O2. Direct treatment towards underlying cause. Workup may include a chest xray (CXR) and ABG.
3. Aspiration
Definition: Inhalation of gastric contents into the tracheobronchial tree. May develop chemical pneumonitis.
Etiology: Post-operative nausea and vomiting (PONV) in the context of unreliable airway reflexes increases risk
Clinical picture: Coughing, wheezing, hypoxia. Workup may include a CXR.
Treatment: In an actively vomiting patient, place in head down and left lateral decubitus. Treatment is supportive otherwise – supplemental O2, consider intubation and suction down ETT, bronchodilators. No role for prophylactic antibiotics or steroids.
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