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Biomedical subjects

M Cumming

Publications and source records attributed to M Cumming.

11 recordsLinked to original sources
PubMed1987

The effect of ketamine anaesthesia on the acidotic fetal lamb.

The following study in pregnant ewes was done to examine the effects of ketamine-oxygen anaesthesia on the fetal lamb made acidotic by partial occlusion of the umbilical cord. Fifteen pregnant ewes were instrumented under general anaesthesia to allow continuous measurement of maternal and fetal mean arterial pressure and pulse rate and for withdrawal of arterial blood samples for blood gas analysis. An occlusion loop was loosely secured around the umbilical cord. Following a recovery period of 48 hours, a tracheostomy was performed on each ewe. After a control period, the umbilical occlusion loop was slowly inflated until fetal pH had decreased to 7.12-7.15. Following inflation the animals were divided into groups A and B. Group A received no anaesthesia. In Group B, the ewes received ketamine 3 mg X kg-1 intravenously and controlled ventilation with FIO2 of 1.0. After ten minutes ketamine 1 mg X kg-1 was given. In both groups radioactive microspheres were injected into the fetus at 0, 5, and 15 minutes. Ketamine anaesthesia in the pregnant ewe abolished the fetal hypertension and bradycardia produced by partial cord occlusion. All fetuses survived the 15 minutes of ketamine anaesthesia and there were no significant changes in arterial blood gases or pH. Blood flows determined by the microsphere method to the brain, heart, and kidneys were not significantly altered by ketamine. We conclude that ketamine-oxygen anaesthesia does not cause further deterioration in the acidotic fetal lamb.

Acidosis↗
PubMed1987

Obstetrical anaesthesia at Winnipeg Women's Hospital 1975-83: anaesthetic techniques and complications.

The obstetrical anaesthesia experience of the Winnipeg Women's Hospital from 1975 to 1983 was reviewed (n = 22,925 infants). Use of narcotics in labour for analgesia decreased from 38.7 to 18.3 per cent of the deliveries. For analgesia during spontaneous vaginal deliveries, epidural anaesthesia increased from 6.0 to 24.0 per cent, inhalational analgesia decreased from 53.7 to 3.2 per cent while "no anaesthetic intervention" rose from 40.3 to 72.8 per cent. Use of epidural anaesthesia for Caesarean section increased from 58.7 to 82.6 per cent. The most common acute complications of anaesthesia were hypotension and inadvertent dural puncture during epidural catheterization. The incidence of hypotension decreased from 28.3 to 17.4 per cent during the nine-year period. Dural puncture decreased from 4.7 to 1.1 per cent of all epidural administrations. Postpartum complaints (that were thought to be related to anaesthesia) were mainly headache, back pain and sore throat. The incidence of these complaints also decreased over the study period.

Analgesics, Opioid↗
PubMed1987

Paresthesias and motor dysfunction after labor and delivery.

The incidence of paresthesias and motor dysfunction associated with 23,827 deliveries at Winnipeg Women's Hospital during a 9-yr period (1975-1983) was 18.9/10,000 deliveries. All the symptoms resolved within 72 hr after supportive therapy only. The frequency of paresthesias and motor dysfunction was greater in primiparas, women who had forceps- or vacuum-assisted deliveries, and women who had epidural or general anesthesia. Significant neurologic deficits after labor and delivery with or without epidural anesthesia were rare. Epidural anesthesia is a safe technique in this regard.

Anesthesia, Epidural↗
PubMed1986

Isoflurane potency and cardiovascular effects during short exposures in the foetal lamb.

Isoflurane is a relatively new volatile anaesthetic in clinical practice and increasing use for obstetrical patients might be expected. A previous study demonstrated that a 60-90 minute exposure of the foetus to isoflurane resulted in a significant fall in foetal cardiac output with development of foetal acidosis. To determine the cardiovascular effects of a shorter exposure of the foetal lamb to isoflurane and the potency (MAC) of isoflurane in the foetus, the following study was done. Eleven pregnant ewes were surgically prepared by placing indwelling arterial and venous catheters into the mother and foetus. After a 48-hour recovery period, isoflurane, two per cent in oxygen, was administered to six ewes via a tracheostomy for 30 minutes. Foetal cardiac outputs and regional blood flows were measured by the microsphere method. In five ewes the concentration of isoflurane was varied and MAC determinations were done on both ewe and foetus. Arterial blood levels of isoflurane were used to determine foetal MAC. Exposure to isoflurane resulted in a significant decrease in maternal and foetal mean arterial blood pressures and in foetal heart rate. Exposures up to 30 minutes did not result in foetal acidosis or a significant fall in cardiac output. Maternal and foetal MAC for isoflurane were determined to be 0.86 and 0.34 per cent respectively.

Anesthetics↗
PubMed1985

Ovine fetal urine production following maternal intravenous furosemide administration.

The response of the ovine fetus to maternal furosemide administration was studied in six chronically catheterized fetal lamb preparations. These studies indicate that in the chronic sheep model maternally administered diuretics do not augment fetal urine production. Additionally, passage of the drug from the maternal intravascular compartment to the fetal intravascular compartment could not be demonstrated. It is suggested that on the basis of these data, the results of the "Lasix challenge test" should be interpreted with caution when they are used to evaluate human fetal renal function.

Amniotic Fluid↗
PubMed1979

Prophylactic blood patch does not prevent post lumbar puncture headache.

Of 86 patients in whom accidental puncture of the dura occurred during insertion of a needle for induction of epidural analgeisa for labour and delivery, 11 received a prophylactic blood patch at the completion of delivery. Of the 75 patients with no prophylactic blood patch, 59 per cent developed post-lumbar-puncture headache, while 54 per cent of those who had a prophylactic blood patch developed headache. The prophylactic blood patch appears to have no value in preventing post-lumbar-puncture headache in this small group of patients.

Adult↗
PubMed1978

Gastric volume and pH in out-patients.

We measured the volume and pH of the gastric content of 21 out-patients and 21 in-patients under general anaesthesia. Gastric tubes were inserted after induction of anaesthesia, and gastric fluids were withdrawn for pH determinations. Gastric volumes were measured by a dilution technique using polyethylene glycol as the indicator and also by measurement of the volume aspirated through a gastrict tube. Out-patients had a mean gastric volume of 69 +/- 17 ml while in-patients had a mean volume of 33 +/- 4 ml. The average gastric pH for the out-patients was 1.8 +/- 0.2 and for the in-patients 2.0 +/- 0.3. Four out-patients had more than 75 ml of gastric fluid of pH less than 2.0. Aspiration through a gastrict tube did not empty the stomach completely and the volume thus obtained gave a falsely low estimate of the gastric volume.

Adult↗
PubMed1977

Foetal deterioration following thiopentone-nitrous oxide anaesthesia in the pregnant ewe.

Six pregnant sheep were chronically prepared with indwelling catheters in maternal and foetal vessels and a flow probe around a maternal uterine artery. They were anaesthetized the following day with thiopentone and nitrous oxide (70 per cent)--oxygen (30 per cent) maintenance with tracheal intubation. Maternal uterine blood flow fell about 20 per cent following induction of anaesthesia. This resulted from uterine vasoconstriction which, in turn, probably resulted from maternal catecholamine release during light anaesthesia. The foetus in utero developed a mixed metabolic and respiratory acidosis and a fall in oxygen saturation. The possibility that light maternal anaesthesia increases rather than decreases neonatal depression is discussed.

Acid-Base Equilibrium↗