Plasma cholinesterase in pregnancy--effect of enzyme activity on the duration of action of succinylcholine.

The duration of action of succinylcholine, 1 mg/kg and plasma cholinesterase activity were compared in 25 pregnant women undergoing cesarean section and 25 non-pregnant women undergoing elective surgery. Neuromuscular activity was assessed by observation of thumb adduction, following stimulation of the ulnar nerve at the wrist. The duration of action of succinylcholine was significantly longer and enzyme levels significantly lower in the pregnant women. Monitoring of neuromuscular function is recommended when succinylcholine is used in pregnant women.

Midazolam for prolonged intravenous sedation in patients with tetanus.

Midazolam was used for prolonged sedation in ten adult patients with severe tetanus in the Intensive Care Unit for periods ranging from 10 to 50 days. An infusion was started soon after induction and adjusted according to clinical needs. All the patients were intubated and ventilated and in addition received morphine 1-2 mg/hr and alcuronium or pancuronium infusion. Two patients died from complications of tetanus. Six patients recovered from the effects of midazolam within 24 hrs of the cessation of infusion. Recovery took 48 and 72 hrs respectively in the other two patients. Midazolam is a suitable drug for long-term sedation in patients with tetanus. However, dose requirements are variable and recovery may be delayed in some patients.

Atracurium and severe hepatic disease: a case report.

Atracurium is a new non-depolarising neuromuscular blocking agent, metabolized through Hofmann elimination. A case is presented in which a 45-year-old patient with severe liver disease showed a decreased response to atracurium. The possible causes of resistance to atracurium are discussed. We conclude that atracurium may be used in patients with severe hepatic disease.

Atracurium for short surgical procedures: a comparison with succinylcholine.

A comparison was made between atracurium and succinylcholine in 40 patients undergoing short gynaecological procedures of 30 minutes or less. Good intubating conditions were produced in 76.7 +/- 39.3 seconds (mean +/- S.D.) with succinylcholine 1 mg . kg-1 and 198 +/- 84 seconds with atracurium 400 micrograms . kg-1. Muscle relaxation was maintained with the initial dose of atracurium or with repeated boluses of succinylcholine. The mean time of surgery was 17.65 +/- 5.3 minutes in the atracurium group and 15.2 +/- 4.6 minutes in the succinylcholine group. Residual neuromuscular block with atracurium was reversed with neostigmine 0.036 mg . kg-1 and atropine 0.018 mg . kg-1. Recovery of neuromuscular function following reversal, assessed by return of all responses to train-of-four stimulation occurred in 5.05 +/- 4.6 minutes in the atracurium group but half the above doses of neostigmine and atropine were repeated in three patients. We conclude that a single dose of atracurium 400 micrograms . kg-1 is suitable for intubation and maintainance of muscle relaxation for short surgical procedures. However, the onset of action is slow, compared to succinylcholine. Residual neuromuscular block can be antagonised with standard doses of neostigmine, less than 20 minutes after the initial dose of relaxant. Atracurium appears to be a suitable alternative for short procedures where succinylcholine is unsuitable or contraindicated.

Anaesthesia for renal transplantation in sickle cell disease.

Sickle cell disease (SCD) is associated with many pathological and functional abnormalities affecting all organ systems. Renal manifestations of SCD may result in end-stage renal disease (ESRD), which can be treated by chronic haemodialysis or renal transplantation. Renal transplantation was successfully performed in a 25-yr-old male with sickle cell beta-thalassaemia and nephrotic syndrome. We present a case report of this patient, a discussion of the renal complications associated with SCD and the perioperative management of a patient with SCD undergoing renal transplantation.

Epidural ketamine for postoperative analgesia.

Thirty-four patients of ASA physical status I or II scheduled for gall bladder surgery were studied in a comparative prospective trial to evaluate the efficacy of epidural and intramuscular ketamine for postoperative pain relief. They were divided randomly into three groups. Group I (11 patients) received 30 mg intramuscular ketamine. Group II (10 patients) and Group III (13 patients) received 10 and 30 mg ketamine in 10 ml saline respectively, through epidural catheters. Pain was evaluated every two hours for the first 24 hours post-operatively by using a linear analogue pain scale from 0-10. Ketamine was given on the patient's request and whenever the pain score exceeded three. Ketamine produced analgesia in all patients studied. The reduction of pain score after two and four hours in Group I and III was significant when compared to Group II. Seven patients (54 per cent) in Group III did not require further analgesia after the initial injection. However, following 10 mg epidural ketamine or 30 mg IM ketamine, post-operative pain was more frequent. Four patients who received epidural ketamine complained of transient burning pain in the back during injection. No patient developed respiratory depression, psychic disturbance, cardiovascular instability, bladder dysfunction or neurologic deficit. It is concluded that 30 mg epidural ketamine is a safe and effective method for postoperative analgesia.

The pattern of train-of-four fade after atracurium: influence of different priming doses.

This study was designed to investigate the effect of three different priming doses of atracurium--0.06, 0.07, and 0.08 mg/kg--followed 3 min later by the remainder of a 0.5 mg/kg dose on the relationship between the depression in the first twitch of the train-of-four (T1) and train-of-four (TOF) fade. This relationship was studied after the administration of the full dose of the relaxant in all groups. Of all the priming doses, 0.08 mg/kg atracurium, when followed 3 min later by 0.42 mg/kg atracurium, had a significantly greater fade in the TOF ratio at any given T1 value. This may indicate significant prejunctional activity. Acceleration of the onset of neuromuscular blockade was, however, evident in all groups that received atracurium in divided doses. The implication is, therefore, that prejunctional activity may not contribute significantly to the acceleration of onset of neuromuscular blockade after administration of atracurium in divided doses, as described in this study.

Rapid tracheal intubation with atracurium--a comparison of priming intervals.

To determine the optimal interval between the administration of the priming dose and the intubating dose, atracurium was given to 44 patients either in a single dose of 0.5 mg X kg-1 or in an initial dose of 0.06 mg X kg-1 followed two, three or five minutes later with 0.44 mg X kg-1. When atracurium was given as a single bolus of 0.5 mg X kg-1 the time to 100 per cent twitch suppression (onset time) was 90.9 +/- 36 (mean +/- SD) seconds. When the priming interval was two minutes, the onset time of the intubating dose was 76.6 +/- 42.2 seconds (p = NS). But when the priming interval was three or five minutes, the onset times were 42.2 +/- 16.5 (p less than 0.01) and 52.6 +/- 28.8 (p less than 0.05) seconds respectively. Waiting for five minutes after the administration of the priming dose did not improve the intubating conditions. It is concluded that three minutes appears to be the optimal time interval for the administration of atracurium in divided doses. When a priming dose of atracurium is given three minutes before the intubating dose, it can provide an alternative to succinylcholine for rapid endotracheal intubation.

Priming with atracurium: improving intubating conditions with additional doses of thiopental.

The effects of different intubating doses of atracurium on the time of onset, and the effect of an additional dose of thiopental on intubating conditions, were studied in 72 patients divided into six groups (n = 12 in each). Stratified sampling was used to obtain an even sex distribution. Groups I, III, and V (controls) received atracurium as a single bolus dose of 0.4, 0.5 or 0.6 mg/kg respectively. Groups II, IV, and VI received an initial (priming) dose of 0.05 mg/kg followed 3 min later by 0.35, 0.45, or 0.55 mg/kg respectively. The time of onset, that is the time from the intubating dose to complete suppression of the train-of-four (TOF) response, was significantly accelerated after administration of atracurium in divided doses. Increasing the intubating dose of atracurium after an initial 0.05 mg/kg from 0.35 to 0.55 mg/kg did not result in further significant acceleration of the onset time, but resulted in prolongation of the duration of neuromuscular blockade. When divided doses of atracurium were given, administration of 2 mg/kg thiopental (in addition to the 5 mg/kg used for induction) before the injection of the intubating dose resulted in improvement of intubating conditions as reflected by statistically significant changes in intubating scores. This result was probably due to the increase by thiopental in the depth of anesthesia. Therefore, when thiopental is given as supplement, the priming technique can be made to provide better conditions for tracheal intubation in less than 90 sec.