SummaryThe effects of intravenous morphine (10 mg/70 kg) on the ventilatory response to CO, were studied in two groups of subjects, young (18-29 years) and old (66-85 years), prior to elective surgery. In both groups morphine caused a signijcant depression of respiration as judged by a reduction in the slope of the COz response curve. a reduction in the calculated ventilation at an end tidal CO, tension of 7.3 kPa, a rise in resting end tidal C02 and a rise in the CO, threshold. There were no significant differences between the two groups in the changes produced by the drug, suggesting that acute respiratory depression after a single intravenous injection of morphine is similar in old and young people. Key wordsAnalgesics. narcotic; morphine. Measurement techniques; C 0 2 response.There is a widespread clinical impression that morphine causes greater respiratory depression in the old than in the young. Much experimental evidence fails to support this impression. Whilst breathing a C0,-enriched mixture after intravenous morphine administration, a group of elderly men achieved the same absolute ventilation as young men.' After intravenous or intramuscular morphine administration the changes in respiratory frequency u) and minute volume (p~) led to the conclusion that the aged did not possess the great sensitivity to morphine often attributed to them.2 After subcutaneous3 or intravenous4 morphine the changes in respiratory frequency, minute volume and end tidal COz tension (&'co2) were similar in young and old subjects.We have studied the effect of age on the ventilatory response to COz after intravenous administration of morphine by observing the changes in the C02 tension/ventilation curve and the calculated ventilation at a PE'CO, 7.3 kPa (v7.3). In addition, we observed the changes in the resting PE'co, and the 'CO, threshold' which is the level of PE'co, at which ventilation begins to increase from the basal level. MethodsTwo groups of 12 patients were studied. One Morphine in the elderly 91 1 group of six males and six. females was aged 66-85 years (mean 76 years) and the other group of six males and six females was aged 18-29 years (mean 25 years). The mean weight of the older group was 59 kg (43-85 kg) and the mean weight of the young group was 69 kg (51-86 kg). All patients were free from overt cardiorespiratory disease and gave informed consent for the study which was approved by the hospital ethical committee. Each patient was studied whilst lying comfortably on a trolley in the anaesthetic room prior to elective surgery. All subjects had been starved for at least 8 hours and had received no other drug. The measurement of ventilatory response to CO, was based on the method described by Read.5 The subject rebreathes into a small bag containing C02 at a partial pressure close to that of mixed venous blood. The progressive rise in Pco, within the bag stimulates respiration and the slope of the ventilation curve reveals information about the sensitivity of the respiratory centre.Each subject wore a nose cli...
SummaryThe construction and function of a teaching aid for the insertion of epidural injections is described.
SummaryTwenty seven insulin-dependent diabetic patients received a continuous intravenous infusion of an insulinglucose-potassium solution whilst undergoing elective surgical or obstetric procedures. The dose of insulin was adjusted according to blood glucose values. I t was concluded that the regimen is safe and simple to manage and should result in good control of blood glucose levels.
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