BACKGROUND: Propofol and ketamine are believed to reduce airway resistance. The aim of the present study was to compare the effect of propofol and ketamine on respiratory mechanics after endotracheal intubation in children.

METHODS: Forty pediatric patients were assigned randomly to two groups: propofol (n = 20) and ketamine (n = 20). Patients were anesthetized with propofol (2 mg/kg) or ketamine (2 mg/kg). All patients were paralyzed with rocuronium (0.8 mg/kg) and intubated and ventilated mechanically (ETCO₂: 30-40 mmHg, tidal volume: 10 ml/kg, respiratory rate: 15-25 time/min). Peak inspiratory pressure (PIP), respiratory resistance (Rr), dynamic compliance (Cdyn) and expiratory tidal volume (Vte) measurements were recorded at five time points; 0.5 min after intubation without sevoflurane (baseline), following 2.5 min, 5 min, 7.5 min and 10 min of ventilation with 2% sevoflurane- 50% nitrous oxide.

RESULTS: Rr at 0.5 min after intubation was 27.4 ± 12.7 cmH₂O/L/s in the propofol group, and 30.0 ± 13.5 cmH2O/L/s in the ketamine group. Cdyn at 0.5 min after intubation was 28.0 ± 9.9 ml/cmH₂O in the propofol group, and 25.1 ± 10.6 ml/cmH₂O in the ketamine group. There was no significant difference in the response of PIP, Rr, Cdyn and Vte between two groups and within groups.

CONCLUSIONS: We suggest that the effects of propofol and ketamine on respiratory mechanics were similar during anesthetic induction in children.