INTRAVENOUS PROPOFOL AND METHOHEXITAL FOR PEDIATRIC MRI SEDATION

The purpose of the present study was to compare two sedation regimens with either propofol (P) or methohexital (M) for elective magnetic res onance imaging (MRI) In children with respect to safety, side effects, recovery, and discharge time. Methods. After Institutional Review Boa rd 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 rece ive a hypnotic induction dose of either M or P. Supplemental bolus inj ections of M or P were administered to maintain adequate sedation. The following parameters were measured: heart rate, oxygen saturation by pulse oximetry (SpO(2)), respiratory rate, end-tidal CO2 (PetCO(2)), s ide effects, and recovery and discharge times. Results. Spontaneous re spiration was maintained in all patients, and ventilatory support was only necessary for 2 min in 1 M patient immediately after the inductio n 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. Fol lowing induction SpO(2) < 90% occurred in 0.49% with M and in 0.64% wi th P (n.s.). Apnoe > 20 s was observed in 2 children each after M and P (n.s.), The frequency of hypoventilation (Pet-CO2 > 48 mmHg) was 0.3 6% in the M group and 0.71% in the P group (n.s.). MRI sequences had t o be repeated in 5% of the children in each group because of spontaneo us movements. The heart rate fell significantly during MRI in both gro ups, while P children had lower frequencies than M children (P < 0.01) , Recovery and discharge times were significantly shorter in the P gro up, 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 childre n undergoing elective MRI. The fast recovery and discharge times seem to offer advantages over general anaesthesia with endotracheal intubat ion. The faster recovery and discharge of only a few minutes after P c ompared with M is without clinical relevance.