[Nalbuphine and piritramid in the postoperative period in young children. 2. External respiration].

The use of opioid analgesics often seems to be necessary for postoperative analgesia in small children. There is a risk however, that interactions between anesthetics and the opioid analgesics may cause significant respiratory depression. There is no reliable information about the influence of nalbuphine and piritramide on respiration in small children. Therefore, the actions of nalbuphine and piritramide versus placebo on the respiratory patterns of 46 children in ASA groups I and II and aged between 1 and 4 years were tested in a randomized double blind trial. METHODS. Selection criteria were: no disturbed development, no signs or symptoms of neurological disease, uncomplicated operation, no pain at time of admission, no indication for urgent operation, written parental consent. Operations, premedication and anesthesia were standardized as mentioned in the comparison paper. Anesthesia was induced and maintained with oxygen in nitrous oxide and halothane (FiO2:0.3). Intubation was performed without the use of any relaxant. Postoperatively the ventilation was continued with the same FiO2 and with 0.5 vol% of halothane over a period of at least 20 min until spontaneous breathing was reestablished and stable ventilatory parameters were obtained. A single bolus injection of either nalbuphine or piritramide 0.1 mg/kg or a placebo was then given i.v.. The breathing parameters VT, VI, respiratory rate, maximal inspiratory flow and the inspiratory/expiratory time ratio were evaluated using the computer-assisted pneumotachometric device with hot wire anemometers (Büttner et al.). They were measured before and 2, 5, 10 and 15 min after the drugs were administered. Capillary blood-gas values were sampled before and 10 min after administration of the drug and again 5 min after extubation. Heart rate and blood pressure were recorded by means of a Dinamap monitor. Statistical analysis of the data was carried out by means of the chi 2-test or Fisher's exact test when appropriate. For the metric data analysis of variance was performed. A full factorial design was calculated with drugs and time after injection as factors and baseline values as a covariate. Multiple comparisons were performed using the Tukey test. The level of significance was set at P less than 0.05. Homogeneity was considered when p greater than 0.2. RESULTS. In spite of randomization the 3 groups could not be regarded as homogeneous for weight. In 4 of the 46 children apnea developed after drug administration and controlled ventilation was needed. These were all in the piritramide group. This result was significant against nalbuphine and placebo. There was no significant correlation between the apnea and any anamnestic, demographic or respiratory parameters. Since apnea and breathing constitute different qualities, a pooling of the apnea data and the non-apnea data within the piritramide group is not allowed...