The effects of the new, highly selective alpha 2-adrenergic agonist, dexmedetomidine, were studied in a randomized, placebo-controlled, double-blind trial in 24 ASA I patients. Dexmedetomidine 0.6 micrograms kg-1 or saline was given i.v. 10 min before induction of anaesthesia. The required dose of thiopentone was significantly (P less than 0.001) smaller in the dexmedetomidine group (mean 4.4 (sd 0.9) mg kg-1) than in the control group (6.9 (1.6) mg kg-1), and the drug attenuated the cardiovascular responses to laryngoscopy and tracheal intubation. The concentration of noradrenaline in mixed venous plasma was smaller in the dexmedetomidine group during all phases of induction (P less than 0.01). During surgery, fentanyl was required in a dose of 0.5 (0.6) mg kg-1 and 2.8 (2.6) mg kg-1 in the dexmedetomidine and control groups, respectively (P less than 0.001). During 2 h postoperative follow-up, oxycodone 0.06 (0.06) mg kg-1 and 0.16 (0.1) mg kg-1 (P less than 0.05) was given to the two groups respectively.

DEX increased perioperative haemodynamic stability in patients undergoing brain tumour surgery. Compared with fentanyl, the trachea was extubated [corrected] faster without respiratory depression.

We have studied the haemodynamic changes, QT intervals and catecholamine responses to induction of anaesthesia and tracheal intubation in 24 ASA I patients allocated randomly to receive either propofol 2.5 mg kg-1 or thiopentone 5 mg kg-1 over 60 s. After disappearance of the eyelash reflex, the lungs were ventilated with 100% oxygen for 3 min. The trachea was intubated after administration of vecuronium. With thiopentone, heart rate (HR) was greater than with propofol before intubation (P < 0.05). During induction, systolic (SAP) and diastolic arterial pressure (DAP) decreased more with propofol than with thiopentone. The QT interval was prolonged only during induction with thiopentone. In both groups, HR, SAP, DAP and the QT were increased in response to intubation (P < 0.001). The SAP and QT interval responses to intubation were significantly greater with thiopentone than with propofol (P < 0.05). One patient in the thiopentone group with a significantly prolonged QT interval had episodes of bigeminy and ventricular tachycardia. In both groups, concentrations of noradrenaline in mixed venous plasma increased after intubation (P < 0.001). Concentrations of adrenaline increased after intubation only in the thiopentone group (P < 0.001).

The incidence of a difficult laryngoscopy or intubation varies from 1.5% to 13%, and failed intubation has been identified as one of the anaesthesia-related causes of death or permanent brain damage. Problems in the airway management can be predicted based on previous anaesthesia records, the medical history of the patient and a physical examination. Several radiological measurements have been reported to be associated with a difficult intubation. The sensitivities of the commonly used bedside tests i.e, the Mallampati classification and the thyromental distance have been reported to be from 42% to 81%, and from 62% to 91%, respectively. The figures for the specificity have varied from 66% to 84% and from 25% to 82%, respectively. The other subjective assessments and objective measurements employed for the prediction of a difficult intubation reach comparable sensitivities and specificities. Evidently, the positive predictive value is improved, if combinations of tests are used.

SummaryConcomitant hypoxaemia and tachycardia in the postoperative period is unfavourable for the myocardium. Since hypoxaemia per se may be involved in the pathogenesis of postoperative tachycardia, we have studied the effect of oxygen therapy on tachycardia in 12patients randomly allocated to blinded air or oxygen by facemask on the second or third day after major surgery. Inclusion criteria were arterial hypoxaemia (oxygen saturation < 92%) and increased heart rate (> 90 beat.min-I). Each patient responded similarly to oxygen therapy: an increase in arterial oxygen saturation and a decrease in heart rate ( p < 0.002). Thus, postoperative supplementary oxygen has a positive efect on the cardiac oxygen delivery and demand balance.