The effect of fentanyl on arginine vasopressin and cortisol secretion during anesthesia.

The effects of nitrous oxide-oxygen plus small doses of fentanyl with (N = 7) and without (N = 15) naloxone and the effects of nitrous oxide-oxygen plus halothane (N = 13) on plasma concentration of arginine vasopressin (AVP) and cortisol were studied in normal patients before and during gynecologic laparotomies. Patients given fentanyl alone received incremental doses of 0.002 mg/kg before, during, and after induction of anesthesia. Naloxone, when given, was injected in doses of 0.005 mg/kg before administration of fentanyl. In the fentanyl group, the induction of anesthesia resulted in a significant increase in the plasma AVP levels and a significant decrease in cortisol levels. In contrast, while the halothane group also showed a decrease in plasma cortisol level, there was no change in the AVP levels. There were comparable increases in AVP and cortisol levels in both groups during surgery. Administration of naloxone before fentanyl prevented the increase of plasma AVP levels during anesthesia and surgery and blunted the elevation of plasma cortisol during surgery. Our results suggest that the increase in plasma AVP levels after induction of fentanyl anesthesia may not be induced by the stress of intubation and that small doses of fentanyl may cause AVP release during anesthesia.

Fetal and maternal catecholamines in cesarean section.

The maternal and fetal sympathoadrenal system was studied by radioenzymatic measurement of the release of NA and A in 20 women with full-term uncomplicated pregnancies at cesarean section. Atropinization was performed 30 min or immediately before the induction of anesthesia. Before induction the mean level of maternal plasma NA in the i.v. atropinization group was 1.9 +/- 0.3 pmol/ml and in the i.m. group, 1.2 +/- 0.2 pmol/ml (mean +/- SE) (p greater than 0.05), and the levels of plasma A were 0.5 +/- 0.2 and 0.2 +/- 0.1 pmol/ml, respectively (p greater than 0.05). No significant rise was observed to be connected with the induction of anesthesia. Fetal umbilical arterial NA and A concentrations were higher than maternal values. CA concentration measured in the umbilical artery was 3-6 times higher than the corresponding values measured in the umbilical vein, indicating metabolization of CA in the placenta. Individual variation of fetal NA and A was very high, suggesting great individual alterations in the activity of the fetal sympathoadrenal system.

Changes in placental intervillous blood flow measured by the 133xenon method during lumbar epidural block for elective caesarean section.

The effect of lumbar epidural block on placental intervillous blood flow (IBF) was estimated with the i.v. 133Xe method in 24 cases and in 14 controls. All parturients had uneventful pregnancies and were scheduled for elective caesarean section. Lumbar epidural block caused a significant decrease in maternal mean arterial pressure (MAP), when no preloading infusion with a plasma expander was given. In contrast, the MAP remained unchanged during lumbar epidural block when the parturients received a preloading infusion (Haemaccel, 100 ml/10 kg body weight within 10 min immediately before lumbar epidural block). The IBF decreased to some extent in the non-preloaded group, but increased temporarily in the preloaded group 15 min after the administration of lumbar epidural block. The mean changes of IBF in the non-preloaded and the preloaded groups differed statistically significantly from each other during lumbar epidural block. The IBF of the preloaded group did not differ significantly from the IBF of the control group receiving no lumbar epidural block.

Placental transmission of atropine at full-term pregnancy.

Measurements of placental transmission of atropine were performed during Caesarean section. Twenty-five patients received 3H-atropine 0.5 microgram . kg-1 i.v. 1-30 min before delivery. Maternal venous blood was sampled before the induction of anaesthesia and at the moment of delivery, together with umbilical arterial and venous blood. Total hydrogen-3 activity was determined by liquid scintillation counting. The stability of 3H-atropine was confirmed by paper chromatography. The concentrations in the umbilical vein 1 and 5 min after injection were respectively 12% and 93% of the corresponding maternal value. Those in the umbilical artery were approximately 50% of those in the umbilical vein during the same period.

Placental transfer of 14C-dimethyltubocurarine during Caesarean section.

Placental transfer of 14C-dimethyltubocurarine (14C-dmtc) was studied during Caesarean section. Liquid scintillation counting was used for determination of 14C activity from the maternal and foetal blood samples. Paper chromatography was used to confirm the stability of 14C-dmtc. In all cases 14C-dmtc was able to cross the placenta. Detectable amounts of 14C-dmtc were found in umbilical blood 2 min after injection into the mother. Six and 10 min after injection, the 14C concentration in the umbilical blood was 12% of the corresponding maternal value.

The antiemetic effect of dixyrazine in postoperative patients-- a double-blind study.

A double-blind controlled study based on 197 women undergoing legal abortion (part I) or gynaecological surgery (part II) was employed to estimate the antiemetic effect of dixyrazine. Dixyrazine or part I) or intramuscularly at the end of anaesthesia (part II) and repeated when necessary. The follow-up period lasted 12 and 18 hours, respectively. Overall, a marked antiemetic response in the dixyrazine groups was observed when compared with the placebo treated groups in both part I and II (p less than 0.001). Dixyrazine proved to be superior to placebo especially in patients who were not prone to nausea or who received no major postoperative analgesics (p less than 0.001).