Anaesthesia and the QT interval in humans: effects of halothane and isoflurane in premedicated children.

The effects of halothane and isoflurane followed by subsequent administration of vecuronium on the QT interval have been investigated during the induction of anaesthesia. Fifty-eight children, ASA I, without cardiovascular and electrolyte abnormalities and not receiving any medication were studied. Anaesthesia was induced with either halothane (n = 28) or isoflurane (n = 30), and was maintained until the end of the study with end-tidal concentrations of 2.5-3%. Recordings of ECG, heart rate and systolic arterial pressure were obtained at the following times: prior to induction of anaesthesia; 1 and 3 min after stable end-tidal concentrations of the induction agent had been reached; 1 and 3 min following vecuronium administration; at the time of tracheal intubation; 1 and 3 min later. Halothane significantly shortened the QTc interval (P < 0.05); isoflurane prolonged it (P < 0.001). Heart rate decreased significantly after halothane administration (P < 0.01); in contrast, heart rate increased after induction of anaesthesia with isoflurane (P < 0.05), increasing further after laryngoscopy and tracheal intubation (P < 0.001). Systolic arterial pressure decreased significantly (P < 0.001) in both groups after induction of anaesthesia and remained decreased until the end of the study. It is concluded that halothane may be a better choice than isoflurane for children with a long QT interval.

Anaesthesia and the QT interval in humans. The effects of isoflurane and halothane.

Prolongation of the QT interval may cause potentially hazardous arrhythmias. The effects on the QT interval (QTc, corrected for heart rate) of isoflurane and halothane followed by vecuronium have been investigated during induction of anaesthesia in 51 patients. All patients were ASA 1 or 2, without cardiovascular problems or electrolyte abnormalities and were not receiving medication. Midazolam 0.08 mg.kg-1 was administered intramuscularly for premedication. Anaesthesia was induced with either isoflurane (n = 26) or halothane (n = 25), and the inspired concentration increased to reach an end-tidal concentration of 2.5% to 3%. Recordings of ECG, heart rate, systolic and diastolic arterial pressure were obtained at the following times: prior to induction of anaesthesia; 1 min and 3 min after a stable end-tidal concentration had been reached; 1 min and 3 min following vecuronium administration, at the time of tracheal intubation and 1 min and 3 min later. Halothane significantly shortened QTc (p < 0.05 to p < 0.001), in contrast to isoflurane which prolonged it (p < 0.01). The heart rate decreased (p < 0.01 to p < 0.001) after induction of anaesthesia with halothane and returned to pre-induction values after tracheal intubation. In contrast, heart rate increased after induction with isoflurane and increased further after laryngoscopy and tracheal intubation (p < 0.001). In the isoflurane group, ST depression was noticed in seven patients and nodal rhythm in two, while in the halothane group seven patients developed nodal rhythm and, in two patients, ventricular ectopics were recorded. There were no sequelae. In both groups, systolic and diastolic arterial pressure decreased after induction of anaesthesia (p < 0.01 to p < 0.001), increasing again after intubation.

Limb arterial injuries associated with limb fractures: clinical presentation, assessment and management.

OBJECTIVES: Review of limb arterial injuries associated with limb fractures. DESIGN: Retrospective study. SETTING: University Hospital. MATERIALS AND METHODS: The clinical presentation, assessment and management of 25 patients with upper (seven) and lower (18) limb arterial injuries associated with limb bone fractures has been retrospectively reviewed. MAIN RESULTS: Five patients presented with life threatening injuries and classic signs of acute limb ischaemia, 15 patients had an obvious limb arterial injury, and 5 presented with a suspected limb arterial injury. The site of arterial damage was: superficial femoral (4); popliteal (11); tibioperoneal trunk (3); anterior tibial (4); posterior tibial (3); peroneal (2); axillary (1); brachial (5); radial (4); and ulnar artery (4). The types of arterial repair were: autogenous vein interposition or bypass grafting (17); P.T.F.E. (2); end-to-end anastomosis (14); and ligation (8). The popliteal vein was injured in six cases, repaired in four and ligated in two; the superficial femoral vein was injured in four cases, repaired in three and ligated in one; and the axillary vein was injured in one case and was ligated. Primary nerve repair was employed in six out of seven injured nerves. Skeletal fixation preceded vascular repair in 21 patients and in four a Javid shunt was used. Intraoperative fasciotomy was performed in 12 out of 18 patients with lower limb ischaemia. Completion arteriography revealed residual thrombi in the distal foot of four patients, in whom intraarterial thrombolysis was effective. During the follow-up period of 1.5 to 2 years, the upper and lower limb preservation rate was 100 and 89%, respectively. The upper limb function was judged excellent in five patients, good in one and fair in one. In the lower limbs it was excellent in 11 patients, good in three, fair in one and poor in one. CONCLUSIONS: To ensure life and functional limb salvage of patients with devastating vascular injuries, a well organised multidisciplinary approach is necessary.