Cerebral arteriovenous difference of oxygen during gradual and sudden increase of the concentration of isoflurane for induction of deliberate hypotension.

In 20 patients undergoing surgery for cerebral aneurysms, hypotension was induced with either gradual (over 5 min) or sudden increase of inspiratory concentration of isoflurane from 0.5% to 3%. Both modes elicited the same speed of induction of deliberate hypotension and similar decreases of cerebral arteriovenous difference of oxygen (AVDo2). The overall median values of mean arterial blood pressure decreased from 75.5 (range 64-90) mmHg (10 (8.5-12.0) kPa) to 55 (40-66) mmHg (7.3 (5.3-8.8) kPa) and the overall AVDo2 decreased from 6.75 ml/100 ml (3.8-9.4 ml/100 ml) to 5.85 ml/100 ml (2.6-8.1 ml/100 ml) within 10 min. It is concluded that irrespective of gradual or sudden increase of isoflurane concentration, cerebral blood flow is in surplus of metabolism and a favourable oxygen demand/supply ratio is maintained during induction of deliberate hypotension by isoflurane below 2.5 MAC.

Infusion of vecuronium assessed by tactile evaluation of evoked thumb twitch.

In 15 patients (ASA I-II) undergoing intraabdominal gynaecological surgery, muscle paralysis for tracheal intubation and surgery was achieved by a combined bolus and demand infusion of vecuronium. The initial loading dose of 67 micrograms kg-1 and the rate of subsequent infusion were determined by evaluation of the tactile twitch response to train-of-four (TOF) stimulation of the ulnar nerve while the neuromuscular blockade obtained was recorded blindly for control on the contralateral arm. A maintenance dose of 4.9 mg h-1 (2.0-7.6 mg h-1) produced a smooth course of blockade with minimum and maximum values of twitch height during infusion of 2% and 12%, respectively. A period of 15.9 min elapsed from the end of infusion to a TOF-ratio of 0.7, when neostigmine 2.5 mg was administered at the point of two palpable twitches to TOF-stimulation. Simple tactile evaluation of peripheral nerve stimulation is sufficient to determine the infusion rate of vecuronium required to produce stable and appropriate neuromuscular blockade during intra-abdominal surgery.

Maintenance of constant 95% neuromuscular blockade by adjustable infusion rates of pancuronium and atracurium.

In a double-blind study, 39 patients (ASA groups I-II,) were given either pancuronium or atracurium as an infusion during surgery. The drugs were given as an initial loading dose of 0.064 mg kg-1 or 0.30 mg kg-1, respectively, followed by an infusion, the rate of which was regulated to produce a constant 95% depression of the evoked twitch response throughout surgery. No significant difference in the number of corrections of the infusion rate per hour was found (4.6 v. 4.9). Mean infusion maintenance doses were 35 and 356 micrograms kg-1 h-1, respectively. The inter-individual variability of maintenance doses for the two drugs did not differ, the coefficients of variation being 0.32 and 0.24. On stopping the infusion, the patients given atracurium recovered to a 15% twitch faster than those given pancuronium. In addition neostigmine produced a quicker recovery in this group. Thus atracurium may be a more satisfactory drug for use by infusion.

Chronic constrictive pericarditis treated with total pericardiectomy.

The early and late results of total pericardiectomy performed during a 30-year period in 34 patients with chronic constrictive pericarditis are presented. The overall hospital mortality was 8.8%. The cumulative 5-, 10-, and 30-year survival rates were 79%, 65% and 53%, respectively. Preoperatively, 94% of the patients were classified in functional class III or IV (NYHA classification). After 3 months' follow-up, 94% of the surviving patients were in functional class I or II. After an average 14.2 year follow-up period, 94% of the surviving patients were in functional class I, and of these 72% were in fulltime jobs. It is concluded that the tendency towards early surgery should be encouraged, especially because the chronic state is accompanied by deleterious effects.