Haemodynamic and Catecholamine Responses to Induction of Anaesthesia and Tracheal Intubation: Comparison Between Propofol and Thiopentone

Abstract

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).

A Comparison Of Pressor Response To Induction & Endotracheal Intubation With Thiopentone And Propofol.Prospective,Randomised Study.

“…SBP, DBP decreased significantly after propofol prior to intubation whereas there was significant increase in arterial pressure after intubation after Thiopentone in all three groups. The results were confirmed by S.Coley et al 12 , C. C. Tzen 13 14 .…”

Effects of target concentration infusion of propofol and tracheal intubation on QTc interval*

“…Lindgren et al [15], found that tracheal intubation increases heart rate, blood pressure, catecholamine levels and the QTc interval, and that the continuous infusion of catecholamine leads to QTc interval prolongation and amplifies the U wave [23]. Increased plasma catecholamine is related to QTc prolongation and cardiac arrhythmias.…”

“…Generally, it is known that tracheal intubation during induction stimulates sympathetic activity, which, as a result, prolongs the QTc interval [15,16]. In contrast, other studies have shown the opposite, with tracheal intubation decreasing the QTc interval [17].…”

Anaesthesia and the QT interval in humans

“…7, 8. 201, while propofol does not [20]. In the present study all patients were prernedicated with midazolam and this may have influenced the results, though we have recently found in a similar study (unpublished observations) that midazolam does not produce any significant changes in QTc.…”

“…No patient in the halothane group showed any ST depression although seven patients developed a nodal rhythm and in two patients, ventricular extrasystoles were observed. It is unfortunate that the ST segment depression could not be accurately measured because the ECG monitor had no hcilities for voltage calibration (20) 418 (17) 411 (22) 116 (11) 93 (11) 85 (10) 71 (8) 53 (12) 48 (10) 92 (18) 470 (25) 86 (13) 45 (9) 66 (12) 419 (21) 81 (10) (13) 87 (22) 97 (28) 91 (21) 40 (8) 41 (8) 59 (20) 50 (17) 65 (14) 68 (14) 86 (22) 77 (18) 413 (21) 415 (26) 436 (29) Table 2). The differences in HR between the two groups were significant at all times (p<O.OOI), (Fig.…”