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Haemodynamic variables were measured following administration of pipecuronium 70 micrograms.kg-1 and pancuronium 90 micrograms.kg-1 (approximately equivalent to 1.5 x ED95) in patients anaesthetised with fentanyl 50 micrograms.kg-1 and scheduled to undergo coronary artery bypass grafting. There were significant increases in heart rate (22%), mean arterial pressure (10%), cardiac index (16%), and the rate pressure product (35%) following administration of pancuronium. The absolute values of these parameters were, however, within acceptable clinical limits. Administration of pipecuronium produced minimal and insignificant changes in these parameters. Other measured or derived indices showed only small changes with both agents and these were generally insignificant. There were no incidences of significant bradycardia following pipecuronium administration. The results from the present study suggest that pipecuronium would have advantages for use in patients with significant cardiovascular disease.

Summary The anaesthetic management of patients undergoing tracheal resection for tracheal stenosis and the advantage of the maintenance of spontaneous respiration without intubation of the distal tracheal segment is discussed. The case reports of two such patients using a continuous intravenous infusion of Althesin with maintenance of spontaneous respiration are presented. The technique expedited the surgical re-anastomosis due to lack of instrumentation in the surgical field. While some mild respiratory depression as evidenced by carbon dioxide retention did occur, the technique is worthy of consideration for the procedure.

Plasma myocardial, and skeletal muscle digoxin concentrations were measured in 32 patients undergoing cardiopulmonary bypass who were on long-term treatment with digoxin. The patients were divided into 4 groups according to the daily digoxin dose and the interval between discontinuation of the drug and operation. Before bypass, the mean digoxin concentrations were 1.58 nmol/l (1.24 ng/ml) in plasma 65.2 nmol/kg (50.9 ng/g) in the atria, 121.4 nmol/kg (94.98 ng/g) in 11 papillary muscles, and 16.6 nmol/kg (13.0 ng/g) in skeletal muscle. Mean atrial digoxin concentrations were significantly lower tham mean papillary muscle concentrations in 11 patients. Ratios of plasma of myocardial or skeletal muscle digoxin concentrations were very variable. Generally digoxin concentrations were higher in patients on the larger digoxin dose and with the shorter discontinuation time before surgery. These differences attained significance only with plasma digoxin concentrations. There was a slight fall in plasma digoxin concentration during cardiopulmonary bypass but no significant differences were observed between plasma, atrial, or skeletal muscle digoxin concentrations before and at the end of bypass. No clear relation was seen between plasma or atrial digoxin concentrations and postoperative cardiotoxicity. Stopping digoxin 48 hours before operation appeared to account for pre- or post-bypass plasma digoxin concentrations of less than 1.0 nmol/l (0.8 ng/ml) in most of the instances encountered, whereas the 3 patients who developed pulsus bigeminus postoperatively had received 0.5 mg digoxin only 24 hours before operation.

Diazepam and flunitrazepam were compared in equipotent doses as induction agents for premedicated patients having cardiac surgery. Both drugs caused a significant fall in arterial blood pressure, a rise in Paco2 and a fall in Pao2. There was no significant difference between the two drugs in onset time of anaesthesia, cardiovascular or respiratory depression, or quality of induction. There was also no significant difference from induction with thiopentone in these respects. Diazepam, over a 0.2 to 0.6 mg/kg range of doses showed no difference in toxicity, although induction was clinically smoother with the higher dose.

Newly synthesized DNA is undermethylated in E. coli K-12. The amount of N6-methyl deoxyadenylic acid in labeled DNA varied from 0.3 mol% of total adenine for a 2-min pulse to 1.7 mol% for DNA that was labeled for more than two generations.

The marine sciences are on the verge of commercial exploitation by the developing biotechnology industry, using techniques of genetic engineering. Application of these new technologies represents an important opportunity for addressing a ubiquitous and persistent problem of industrialization — toxic waste disposal. As marine biotechnology advances, its application to pollution control in the oceans should be encouraged.

Some cardiovascular and respiratory effects of four non-barbiturate anaesthetic agents were studied in the induction of anaesthesia in cardiac surgical patients in an attempt to achieve cardiovascular stability. The four agents, diazepam, ketamine, nitrous oxide and propanidid were given to four groups of patients with 20 in each group. Ketamine caused a rise in blood pressure while the other three agents caused a fall similar to thiopentone, most marked with propanidid and least with nitrous oxide. Ketamine caused a progressive tachycardia during the period of the study, propanidid caused a tachycardia similar to thiopentone while diazepam and nitrous oxide caused little change in heart rate. With the three intravenous agents there was a fall in PaO2. Arterial carbon dioxide tension fell with propanidid, rose with ketamine and was unchanged with diazepam and nitrous oxide. The quality of narcosis, frequency of ventricular arrythmias and ease of intubation were compared.

One of four groups of patients was not premedicated; the others received diazepam 10 mg by mouth, diazepam 20 mg by mouth or a combination of pentobarbitone orally and morphine and hyoscine intramuscularly. The cardiovascular and respiratory parameters were studied before and after the premedication and any changes in sedation, apprehension and reaction to pain were noted. The ease of induction of anaesthesia in the four groups was compared. Most of the patients who received the pentobarbitone, morphine and hyoscine combination came to theatre calm, sedated and often asleep. They showed no significant cardiovascular or respiratory depression and the induction of anaesthesia was more satisfactory than in the other groups. Two of the patients who were not premedicated became very agitated in the ward and the remainder of the patients in this group were apprehensive in the anaesthetic room and during induction. The effects of diazepam in the two doses studied were intermediate between those who received the pentobarbitone, morphine and hyoscine and those who were not premedicated.