Pharmacokinetics of atracurium besylate in healthy patients (after a single i.v. bolus dose).

The plasma decay of atracurium besylate was examined in two groups of six patients. Group I received atracurium 0.6 mg kg-1 and group II 0.3 mg kg-1 as a single bolus dose i.v. The plasma concentrations were measured by high performance liquid chromatography. An individual two-compartment pharmacokinetic model was used for interpretation. The results from the two groups were not significantly different, giving overall mean values of 2 min (+/- 0.2 SEM) for the distribution half-life (T1/2 alpha), 19.9 min (+/- 0.6) for the elimination half-life (T1/2 beta), 5.5 ml min-1 kg-1 (+/- 0.2) for total clearance (Cl) and 157 ml kg-1 (+/- 7) for total distribution volume (Varea).

Conditions for tracheal intubation using atracurium compared with pancuronium.

Intubating conditions were compared using atracurium 0.6 and 0.8 mg kg-1 and pancuronium 0.08 and 0.1 mg kg-1 in 96 patients. They were randomly allocated and studied at 30, 45, 60 or 75 s after injection of the drug. Smooth intubation was not possible before 60 s with either drug and in 11 patients intubation could not be achieved at the chosen time. Atracurium 0.6 mg kg-1 and pancuronium 0.08 mg kg-1 gave comparable results. Atracurium 0.8 mg kg-1 gave intubating conditions comparable to those obtained with pancuronium 0.1 mg kg-1 at 45 and 75 s and slightly better conditions at 30 and 60 s.

Sedation for outpatient conservative dentistry. A trial of pentazocine supplementation to diazepam and local analgesia techniques.

Pentazocine 30 mg. or 15 mg or a placebo, was administered randomly to forty-nine patients undergoing conservative dental treatment in combination with a local analgesic block and intravenous diazepam. Simple cardiorespiratory measurements were made throughout the treatment period. Patients in the 30 mg pentazocine group required some 6 mg diazepam less than the placebo (control) group (P less than 0.05). Patients receiving 15 mg pentazocine also required less diazepam compared to the control group, but this difference was not statistically significant. There were no significant differences between the three groups either in recovery times or the cardiorespiratory measurements.

Blood carbon dioxide tension changes during hysteroscopy.

During hysteroscopy the uterus may be distended with carbon dioxide (CO2), nitrous oxide (N2O), or Hyskon (a high molecular weight dextran). An initial study in 27 patients (group 1) using arterialized venous blood samples demonstrated rises in carbon dioxide tension (PCO2) when N2O was insufflated by using a laparoscopy insufflating device--a constant-pressure, variable-volume gas source. Cardiovascular collapse occurred in one patient in this group, most probably as a result of macropulmonary emboli of N2O. The rise in PCO2 is accounted for by an increase in physiologic dead space. In another 24 patients (group 2) the gaseous media were introduced by using a constant-volume, variable-pressure gas source; this resulted in minimal changes in arterial PCO2. The choice of whether a gaseous or liquid distending medium is used for hysteroscopy is governed by the state of the endometrium. If a gaseous medium is indicated, then CO2 is preferable to N2O and should be introduced with a constant-volume, variable-pressure gas source.

Enflurane (Ethrane) anaesthesia in man. Metabolism and effects on biochemical and haematological variables.

In 10 patients serum inorganic fluoride increased to a mean peak value of 16 micronmol.litre--1 after 2 h of enflurane anaesthesia. Four days after anaesthesia, serum inorganic fluoride had decreased to the values before operation. The maximum daily inorganic fluoride excretion in urine (UFV) did not exceed 200 micronmol.litre--1. In a group of 20 patients routine biochemical and haematological variables were measured before and after enflurane anaesthesia. There were only minor changes in these variables, attributable to the surgical procedure. It is concluded that renal dysfunction is unlikely to follow enflurane anaesthesia in patients with previously normal hepatic and renal function.

Conditions for tracheal intubation following fazadinium and pancuronium.

Intubating conditions were studied in two groups of patients who received either fazadinium 1 mg/kg or pancuronium 0.1 mg/kg (group 1), or either fazadinium 0.5 mg/kg or pancuronium 0.08 mg/kg (group 2). In group 1 intubating conditions were studied at 30, 45, 60 and 75 s after injection of the relaxant drug, and in group 2 at 60 s after injection. Fazadinium provided better intubating conditions than pancuronium during the first 60 s after administration in group 1 (P less than 0.01). In group 2 there was no significant difference between the conditions provided by the two drugs.

Letter: Laparoscopy explosion hazards with nitrous oxide.

PIP: Hysteroscopy and laparoscopy differ in that in the former the uterine cavity is insufflated with gas or liquid to allow telescopic inspection whereas in the latter the peritoneal cavity is insufflated. Opening of the bowel by diathermy as performed by some physicians is not usually a part of laparoscopic sterilization although it may occur as a complication. In cases where diathermy of the bowel is part of an elect ive procedure nitrous oxide is generally used. For those performing tubal diathermy there is a choice of using carbon dioxide with a risk of cardiovascular collapse nitrous oxide with a theorectical risk of intraperitoneal explosion. Unfortunately, currently available data are insufficient to quantify these 2 risks.^ieng

Cardiovascular changes in labour associated with extradural analgesia using bupivacaine.

Cardiovascular changes were monitored continuously in 13 women during stimulated labour conducted under extradural analgesia with bupivacaine. Three solutions of bupivacaine (0.5% plain, 0.25% with adrenaline and 0.5% with adrenaline) were administered in a random fashion. The results show that the plain solution of bupivacaine was associated with a decrease in central venous pressure and an increase in maternal heart rate which approached statistical significance 40-45 min after administration. These changes did not occur when solutions containing adrenaline were used. The small number of patients and the random administration of the bupivacaine solutions make it difficult to establish the exact significance of the cardiovascular changes observed and a further within-patient study is required.

Cardiovascular effects of extradural analgesia in labour: comparison of bupivacaine with lignocaine.

Two groups of patients who requested extradural analgesia were studied in a within-patient controlled trial and received either 0.5% bupivacaine with adrenaline 5 mug/ml or 0.5% bupivacaine plain as the analgesic agent (first group) or 0.5% bupivacaine or 2% lignocaine both with adrenaline 5 mug/ml (second group). Arterial pressure, central venous pressure (CVP), maternal and foetal heart rate and uterine contractions were monitored continuously. There was no significant difference in any of the cardiovascular measurements when solutions of 0.5% bupivacaine (with or without adrenaline 5 mug/ml) were used. The second group had a statistically significant increase in CVP during the study period in which 2% lignocaine was used. The position of the patient did not affect the cardiovascular measurements in either group. Since the addition of adrenaline 5 mug/ml to bupivacaine solutions did not confer any apparent advantages, it is concluded that plain solutions of 0.5% bupivacaine should be used except in the longest labours.

Assessment of the Von Recklinghausen oscillotonometer.

The Von Recklinghausen Scala Alternans Altera oscillotonometer was assessed in order to establish whether any of the disputed points over its use made a significant difference to the readings obtained. Inversion of a new cuff gave significantly higher systolic readings, but a worn cuff gave consistent results whatever its position. Measurements of systolic and diastolic pressures were not significantly affected by the use of the sustained leak lever provided the leak was small. Maintenance and cleaning of the instrument are essential for its proper working.