Pulmonary hypertension and pregnancy: a series of eight cases.

This is the report of a series of eight patients with pulmonary hypertension (primary and secondary) who delivered at the McMaster University Medical Centre between 1978 and 1987. Seven of the eight patients delivered vaginally and had a successful outcome. The eighth patient was admitted as an emergency and died shortly after Caesarean section under general anaesthesia, performed to save the infant. The other seven patients were all managed by a team, including anaesthetists, cardiologists and obstetricians, from about 25 wk. The patients were hospitalized pre-partum and received oxygen therapy and anticoagulation with heparin. Analgesia in labour was managed, once anticoagulation was reversed, by low concentrations of epidural bupivacaine (0.125%-0.375%) and fentanyl. The patients were monitored during labour and delivery with oximetry and arterial and central venous pressure lines. Pulmonary arterial lines were not used because of increased risk and questionable usefulness. Vaginal delivery was managed with vacuum extraction or forceps lift-out to minimize the stress of pushing. After delivery, all patients were monitored in an intensive care unit for several days, anticoagulation was restarted, and all patients were discharged home taking oral anticoagulant therapy. The successful management of pulmonary hypertension in pregnancy should include team management started early in pregnancy and controlled vaginal delivery utilizing epidural analgesia.

Placental transfer of local anaesthetics in the premature sheep fetus.

This study was designed to test whether there is any difference in the placental transfer of bupivacaine or lidocaine in the early compared to the late preterm maternal/fetal sheep preparation; and whether the premature lamb fetus reacts to a steady state local anaesthetic infusion differently from the same lamb near term. Eleven ewes were studied in two groups receiving bupivacaine (group A) or lidocaine (group B). Hysterotomy and insertion of fetal and maternal lines were performed at 110 days gestation, and studies were repeated weekly using the same local anaesthetic until delivery. We found no difference in maternal or fetal cardiovascular responses to bupivacaine or lidocaine in the early (mean 119 days) compared to the late (mean 132 days) preparations. The levels of bupivacaine and lidocaine in the fetal blood were similar in early and late fetuses, as were the fetal/maternal ratios of both drugs.

A comparative study of continuous and intermittent epidural analgesia for labour and delivery.

This study compares a continuous infusion technique with intermittent "top-up" doses using 0.25 per cent bupivacaine for epidural analgesia for labour and delivery in healthy primiparous patients. Sixty women were randomized into two groups, A (continuous) and B (intermittent). Twenty-eight patients in Group A and 29 in Group B completed the study. We compared the groups with regard to satisfaction with pain relief for both labour and delivery as measured by a Visual Analogue Scale on five occasions during and after parturition. There was no difference between groups at any of the five stages. The difference in pain scores before the epidural and after the epidural was significant for both groups (p less than 0.001). The incidence of missed segments, degrees of motor block, height of sensory block, length of labour and fetal outcome were similar in both groups. Plasma bupivacaine levels were measured in six patients in each group. Mothers in Group A received more drug than those in Group B (p less than 0.01) but plasma bupivacaine levels remained low in the mother and the umbilical cord samples in the sub-set from this group. More women in Group A required outlet forceps (p less than 0.05) whereas mid-forceps and Caesarean section rates were similar in the two groups. Fewer mothers in the infusion group had spontaneous vaginal delivery. We conclude that infusion techniques are as effective as intermittent top-up epidurals and are well received by mothers in labour.

Intramuscular cimetidine and ranitidine as prophylaxis against gastric aspiration syndrome--a randomized double-blind study.

Preoperative cimetidine 300 mg or ranitidine in 50 and 100 mg doses were administered intramuscularly to 120 patients in a randomized double-blind study. The volume and pH of gastric aspirate samples obtained after tracheal intubation and before extubation were measured. The pH of gastric aspirate was higher following ranitidine 100 mg than ranitidine 50 mg or cimetidine 300 mg at both intubation and extubation (p = 0.006). In addition, fewer patients tended to be "at risk" of pulmonary aspiration syndrome (pH less than or equal to 2.5) after ranitidine 100 mg than ranitidine 50 mg or cimetidine 300 mg. Preoperative intramuscular ranitidine 100 mg was found to be suitable for use in protection against gastric aspiration syndrome.

Zomepirac as an analgesic premedication: a comparison of three dosage regimens.

Three regimens of oral zomepirac premedication - 100 mg and 200 mg administered one hour preoperatively, and 100 mg administered 30 minutes preoperatively - were compared in terms of the control of postoperative pain. Primary outcomes were postoperative analgesic requirements, pain intensities and side effects. Sixty patients undergoing laparoscopic sterilization by Fallop ring were studied, using a double blind randomized design. All patients received a standardized general anaesthetic in which narcotic supplementation was avoided. Zomepirac 100 mg, when administered 30 minutes preoperatively, was the preferred regimen in terms of postoperative remedication rates, pain intensity, and side effects. However, the overall rate of remedication was high and was probably a result of the severe pain experienced by these patients in the early postoperative period. Plasma levels of zomepirac at termination of anaesthesia were consistent with the differences in remedication profiles and showed significant correlations with initial postoperative pain intensity, as assessed by an ordinal descriptive scale (r = 0.431, p = 0.025) and time to remedication (r = 0.541, p = 0.004), thus adding validity to the model.

A double-blind comparison of cimetidine and ranitidine as prophylaxis against gastric aspiration syndrome.

Preoperative cimetidine, ranitidine, or placebo were administered, orally or intravenously to 190 patients in a double-blind study. The volume and pH of gastric aspirate samples, obtained after tracheal intubation and before extubation, were measured. Both cimetidine and ranitidine produced higher mean pH levels and thus fewer patients "at risk" should gastric aspiration occur (pH less than or equal to 2.5) than did placebo. Intravenous ranitidine (in both 40- and 80-mg doses) produced fewer patients at risk in the event gastric aspiration should occur than did cimetidine, 300 mg, and the 80-mg dose produced a higher mean pH level. Oral ranitidine, 150 mg, produced a significantly higher mean pH level than did oral cimetidine, 300 mg, and tended to give fewer patients at risk. The volumes of gastric contents aspirated were similar following each of the drugs except that the volume was significantly less two hours following oral ranitidine, 150 mg, than after oral cimetidine, 300 mg.

Alfathesin and etomidate for minor outpatient anaesthesia.

Etomidate was compared with alfathesin for induction and maintenance of anaesthesia in a double-blind fashion in 48 fit patients undergoing minor gynaecological operations as outpatients. The patients were randomized to receive either etomidate 0.3 mg . kg-1 or alfathesin 75 microliters . kg-1 as intravenous induction agents. All patients received fentanyl 1 microgram . kg-1 and breathed 70 per cent nitrous oxide in oxygen. Cardiovascular changes were minimal in both groups and there was less depression of minute volume with etomidate. The incidence of side effects including pain upon injection, involuntary movements, and postoperative nausea and vomiting was higher following etomidate. Recovery was equally rapid in both groups. No adverse reactions were seen. Alfathesin would appear to be preferable to etomidate as an induction and maintenance agent in unpremedicated fit outpatients undergoing minor gynaecological operations.

The pharmacokinetics and pharmacodynamics of minaxolone.

Plasma concentrations of minaxolone were measured in 15 female patients during and for up to 3 hours after a minaxolone and nitrous oxide anesthetic. Nine patients received a single dose and six patients two or three doses of minaxolone. Plasma minaxolone decay can be described by two-compartment kinetics. Distribution is rapid, with a mean half-life of 2.1 minutes, and the elimination half-life is short (47 minutes). Plasma clearance is high (1.55 l./min). Plasma levels of minaxolone at recovery were similar in patients receiving both single and multiple doses, suggesting a valid relationship between plasma level and effect. It is suggested that minaxolone may be a suitable agent for administration by continuous infusion.

A double-blind comparison of carbonated lidocaine and lidocaine hydrochloride in epidural anaesthesia.

Twenty patients having a standard epidural anaesthetic were randomly assigned to receive 20 ml of either carbonated lidocaine 1.73 per cent or lidocaine hydrochloride 2.0 per cent, containing epinephrine 1:200,000. An observer unaware of the solution used measured speed of onset, quality of block, and duration of action. No significant difference was demonstrated in the speed of onset or duration of the block. Carbonated lidocaine gave an improved motor block and showed a trend towards giving fewer missed segments than lidocaine hydrochloride.