• M Semsroth and M Hiesmayr.
• Universitätsklinik für Anaesthesie und Allgemeine Intensivmedizin, Wien.
• Anaesthesist. 1990 Oct 1; 39 (10): 552-6.

AbstractIn ventilated children the cardiorespiratory and metabolic reserve capacities can be extremely limited. Therefore, these children have low thresholds of tolerance for additional stress factors. One of the most obvious aims in the critical postoperative period after heart surgery in children is protection of the cardiorespiratory system against stress reactions. Pain and restlessness are such stress factors. The aim of this study was to identify the most effective form for the application of opiates for analgesia and sedation. The randomized study was performed in 12 ventilated normothermic children after intracardiac surgery. No child was catecholamine-dependent. The biometric and clinical data are shown in Table 1. After stabilization of cardiorespiratory functions in the early postoperative period, the effects on VO2 of morphine hydrochloride, infused continuously (group I, 0.5-1.0 microgram/kg per min), and morphine administered as bolus injections on demand (group II, 0.05 mg/kg) were compared. The mean arterial blood pressure, heart rate, body temperatures and blood gases were measured during a 6-h period in the postoperative intensive care unit. During this time VO2 measurements were done continuously with the DELTATRAC Metabolic Monitor 100 (Datex). Mean values were calculated hourly (T1-T7). In addition, a scoring system according to recently published data was used hourly. Mean values and standard deviations (SD) were calculated and comparisons were carried out with paired two-tailed t-tests. Probability values below 0.05 were considered to indicate statistical significance. The study was accepted by the ethical committee. The score used for postoperative pain showed no difference between the two treated groups. Nevertheless, in the course of VO2, shown in Fig. 1, a difference between groups was detected. During the first hour of the investigation, VO2 increased in both groups. Thereafter, VO2 was significantly lower under continuous morphine application than under bolus injections. VO2 decreased slowly under both regimes but remained significantly lower under continuous application. Continuous application of morphine was more effective in sparing VO2 than bolus injections in ventilated children after cardiac surgery. We conclude that continuous application of morphine represents stress prevention whereas bolus application of morphine is stress therapy. From the clinical point of view it is more effective to prevent than to treat pain and other stress factors in pediatric patients.

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