[Peridural morphine-analgesia. II. Respiratory depression (author's transl)]

In nine healthy young patients ventilatory CO2-response curves and mouth-occlusion pressure were measured after peridural injection of 5 mg morphine hydrochloride diluted in 10 ml saline solution in the lumbar region. Patients were not premedicated. Prior to measurements lower extremity operations were performed under peridural anaesthesia. Five minutes after peridural morphine injection there was a slight reduction in ventilatory response to increasing CO2 (94.7% +!- 15%), which was even more pronounced one hour later (74.5% +/- 14.7%). Mouth occlusion pressure decreased to 86.7% +/- 27.4% after 5 min to 72.4% +/- 13.4% after 60 min. Changes in the relation of the central stimulus P100 to the resulting flow (VT/Ti) was 96.7% +/- 32.5% after 5 min and 95.0% +/- 31.4% after 60 min. These results demonstrate a central respiratory depression after peridural morphine injection with a consequent reduction in ventilatory CO2-response.