Thiopental-sparing properties of butorphanol/diazepam for induction of anesthesia in ambulatory gynecologic surgery.

Butorphanol/diazepam was compared with thiopental for induction of anesthesia, and the thiopental-sparing effects of butorphanol/diazepam determined. One hundred women, American Society of Anesthesiology physical status class I, undergoing ambulatory, elective termination of pregnancy were randomized to receive either butorphanol 2 mg plus diazepam 10 mg, or thiopental, until loss of the lid reflex occurred. The butorphanol/diazepam group received supplemental thiopental as necessary to attain adequate induction of anesthesia. The combination of butorphanol and diazepam significantly reduced the thiopental dose required to produce loss of the lid reflex, from 4.2 +/- 0.8 to 0.8 +/- 0.6 mg/kg (p less than 0.005), with 22 percent of the patients not requiring supplemental thiopental. The intraoperative course and anesthetic requirements were similar between the two groups. Lower recovery room rating scale values upon arrival at the recovery room were attributed to significantly higher weight-normalized doses of butorphanol (p = 0.004) and diazepam (p = 0.005). The duration of the recovery room stay was 68.8 +/- 24.9 min for the control group, and 80.8 +/- 29.0 min for the butorphanol/diazepam-treated patients (p = 0.026). There were no clinically significant differences in anesthesia or postanesthesia recovery. The combination of butorphanol and diazepam has a significant thiopental-sparing effect, and is a useful induction technique for short, ambulatory surgical procedures.

A comparison of the response to suxamethonium in post-partum and gynaecological patients.

The response to suxamethonium was assessed in 20 women undergoing tubal ligation on the first or second post-partum day and in 20 women undergoing interval tubal ligation. The dose of suxamethonium which produced 80% depression of control twitch height was significantly lower in the puerperal patients. Similarly, recovery times following injection of a 20-mg bolus of the drug were significantly longer in the post-partum than the non-obstetric group. Cholinesterase activity, determined in six post-partum women, was inversely related to the time to maximal recovery. Thus, smaller doses of suxamethonium are required in the early puerperium.

Adverse reactions to ketamine anaesthesia. Abolition by a psychological technique.

Ketamine, a phencyclidine derivative, has been used as a general anaesthetic since 1965. Numerous reports of adverse psychological reactions have caused diminished use of this drug. Many investigators have tried by pharmacological means to modify these reactions with limited success. In this study, a psychological strategy has resulted in the absence of any adverse psychological reactions and acceptance of ketamine anaesthesia by all patients. Additionally, all surgeons were satisfied with operating conditions.

Effects of trimethaphan and sodium nitroprusside on hydrolysis of succinylcholine in vitro.

The use of hypotensive agents in combination with succinylcholine may be necessary. Since trimethaphan has been reported to prolong the action of succinylcholine, the authors studied the abilities of trimethaphan and sodium nitroprusside to inhibit hydrolysis of succinylcholine by pseudocholinesterase in vitro. Trimethaphan was found to be a potent noncompetitive inhibitor of pseudocholinesterase (KI = 0.24 micronM). It could be calculated that a typical dose of trimethaphan would approximately double the duration of paralysis produced by the usual dose of succinylcholine. Nitroprusside had no inhibitory effect in vitro. It is concluded that nitroprusside is preferable when a hypotensive agent must be used in conjunction with succinylcholine.

Inhibition of human erythrocyte acetylcholinesterase by succinyldicholine.

When human erythrocyte acetylcholinesterase (AChE) is inhibited by succinyldicholine (SuCh) at low ionic strength, mu = 0.03, two apparent affinity constants for the inhibitor can be distinguished, KI(1) = 5.4 X 10-5 M and KI(2) = 1.3 X 10-5 M. Increasing the ionic strength to mu = 0.58 increases KI(1) to 1.1 X 10-4 M, but abolishes the contribution of KI(2) completely. It is suggested that a similar process may underlie the apparently continuous variation in affinity constant with ionic strength which has been reported for many bifunctional cationic inhibitors. Since KI(2) is in a concentration range commonly attained therapeutically, some of the clinical manifestations of succinyldicholine administration, e.g., muscarinic effects, may be explained by its anticholinesterase action.

Stability of pseudocholinesterase in stored blood.

No significant change in pseudocholinesterase levels was observed in random specimens of whole blood stored for as long as 30 days. Levels in plasma anticoagulated with heparin or ethylenediaminetetraacetic acid declined only slightly. Therefore, massive transfusions do not contraindicate succinylcholine administration.