[Intravenous sedation of spontaneously breathing infants and small children before magnetic resonance tomography. A comparison of propofol and methohexital].

UNLABELLED

The purpose of the present study was to compare two sedation regimens with either propofol (P) or methohexital (M) for elective magnetic resonance imaging (MRI) in children with respect to safety, side effects, recovery, and discharge time.

METHODS

After Institutional Review Board approval, 120 unpremedicated children with a mean age of 26.5 +/- 21.4 months (M) and 28.1 +/- 19.9 months (P) were randomly assigned to receive a hypnotic induction dose of either M or P. Supplemental bolus injections of M or P were administered to maintain adequate sedation. The following parameters were measured: heart rate, oxygen saturation by pulse oximetry (SpO2), respiratory rate, end-tidal CO2 (PetCO2), side effects, and recovery and discharge times.

RESULTS

Spontaneous respiration was maintained in all patients, and ventilatory support was only necessary for 2 min in 1 M patient immediately after the induction dose. The mean loading and total doses for M were 2.3 +/- 0.7 and 6.1 +/- 3.3 mg/kg respectively, and for P 2.3 +/- 0.9 and 5.8 +/- 2.7 mg/kg. Following induction SpO2 < 90% occurred in 0.49% with M and in 0.64% with P (n.s.). Apnoe > 20s was observed in 2 children each after M and P (n.s.). The frequency of hypoventilation (PetCO2 > 48 mmHg) was 0.36% in the M group and 0.71% in the P group (n.s.). MRI sequences had to be repeated in 5% of the children in each group because of spontaneous movements. The heart rate fell significantly during MRI in both groups, while P children had lower frequencies than M children (P < 0.01). Recovery and discharge times were significantly shorter in the P group, at 0.8 min (0.08-4.8) and 2.2 min (0.2-15.0), compared to 1.5 min (0.3-28.5) and 3.5 min (0.6-40.0) in patients receiving P (P < 0.01). No patient required admission to the postanaesthesia care unit and all were free from nausea and vomiting.

DISCUSSION

Intravenous sedation with M or P using the reported technique is a safe regimen for children undergoing elective MRI. The fast recovery and discharge times seem to offer advantages over general anaesthesia with endotracheal intubation. The faster recovery and discharge of only a few minutes after P compared with M is without clinical relevance.