Electrocardiographic changes during microlaryngoscopy in practolol-pretreated patients under balanced anaesthesia.

Electrocardiographic (ECG) changes were studied in 82 adult patients with a mean age of 49 years undergoing microlaryngoscopy. The patients were pretreated with practolol 0.15 mg/kg i.v. 5 min before induction of anaesthesia with thiopental. Anaesthesia was maintained with nitrous oxide in oxygen, fentanyl and suxamethonium-infusion. ECG changes occurred in 49% of the patients before anaesthesia and procedure. Pre-existing ECG changes increased or new changes occurred in 39% of the patients during intubation and in 38% during the procedure. The most common preanaesthetic ECG changes were flat or negative T-wave (18%), sinus tachycardia (13%), ischaemic S-T segment depression (8.5%) and intraventricular conduction disturbance (8.5%). ECG changes during intubation were sinus tachycardia (16%), ventricular ectopic beats (12%), supraventricular ectopic beats (10%) and ischaemic S-T segment depression (10%). The most common changes during microlaryngoscopy were supraventricular ectopic beats (16%), T-wave flattening or inversion (15%), ischaemic S-T segment depression (11%) and sinus bradycardia (10%). In all patients ECG changes disappeared without any special treatment. Unlike our earlier identical study without practolol pretreatment, neither sinus tachycardia nor junctional rhythm occurred during microlaryngoscopy in the present study. The results suggest that practolol pretreatment before microlaryngoscopy is especially useful when sinus tachycardia and junctional rhythm should be avoided.

Comparison of pharmacokinetic and pharmacodynamic parameters following oral or intramuscular atropine in children. Atropine overdose in two small children.

Pharmacokinetic and pharmacodynamic parameters of atropine 0.03 mg/kg p.o. or 0.02 mg/kg i.m. were compared in a double-blind study in 20 children with a mean age of 5.1 years undergoing otolaryngological surgery, mostly adenotomy. Outside the study protocol, two small children accidentally received an overdose of atropine 0.3 mg/kg p.o. In addition to atropine, all children received triclofos 70 mg/kg p.o. Following p.o. administration of atropine, the mean maximum serum concentration of 6.7 nmol/l occurred at 2 h. The corresponding result after i.m. administration was 5.7 nmol/l at 0.5 h. Serum concentrations of atropine were 3.5 and 1.3 nmol/l 8 h after p.o. and i.m. administration, respectively. At 70 min the anti-sialogogue effect was clinically satisfactory after both modes of administration. The heart rate increased statistically significantly only after i.m. administration. The mean maximum rise in the rectal temperature before the start of anaesthesia occurred at 1 h and was 0.5 degrees C in the p.o. group and 0.7 degrees C in the i.m. group. The flush phenomenon, mostly on the face and sometimes also on the chest, occurred in both groups, being more intense in the i.m. group than in the p.o. group. The children who developed flush had a statistically significantly higher rise in rectal temperature than the children without flush. There was a positive but weak correlation between the serum concentration of atropine and the heart rate, whereas the correlation between the serum concentration after i.m. atropine and the rectal temperature was weakly negative. On the basis of the present study, there were no decisive differences between the effects and side-effects of the two modes of administration of atropine.(ABSTRACT TRUNCATED AT 250 WORDS)

Attenuation of the cardiovascular intubation response with N2O, halothane or enflurane.

The circulatory intubation response was studied in 75 normotensive, otolaryngological patients after a thiopentone-suxamethonium induction followed by 2 min artificial ventilation with 100% oxygen (control), 70% nitrous oxide in oxygen (N2O), halothane 2% with N2O, enflurane 3% with N2O or enflurane 5% in oxygen. The above study groups (n = 15) were chosen after preliminary experiments performed in 25 different patients with halothane 2% (n = 8) or enflurane 3% (n = 6) in oxygen, which did not prevent the increase of arterial pressure after intubation, or with halothane 3% (n = 11) which attenuated the pressor response but caused cardiac arrhythmias in 55% of patients. Enflurane 5% in oxygen attenuated the increase of systolic arterial pressure by 53%, enflurane 3% with N2O by 34% and halothane 2% with N2O by 31%. The increase in heart rate after intubation was lowest in the halothane 2% with N2O group, but there were no statistically significant differences between the groups. Cardiac arrhythmias were commonest in the enflurane 3% with N2O group (20%) and they did not occur in the halothane 2% with N2O group. Considering the total effect on arterial pressure, heart rate and rate-pressure product, we recommend the combination of halothane 2% with N2O.

Effect of combinations of topical anaesthesia, fentanyl, halothane or N2O on circulatory intubation response in normo- and hypertensive patients.

Attenuation of the circulatory intubation response was studied using the following combinations: oropharyngeal topical anaesthesia (OTA) + fentanyl 2 micrograms/kg (F2), OTA + 2% halothane with 70% nitrous oxide (H2N2O) or F2 + H2N2O. Firstly, it was observed in 48 normotensive patients that the combinations of OTA + F2 or F2 + H2N2O totally prevented the intubation response; OTA + H2N2O, on the other hand, was less effective. Secondly, the effect of OTA + F2 was studied in 26 hypertensive patients and their 26 normotensive controls of the same age group. The combination prevented the circulatory intubation response also in the hypertensive patients, whose circulatory reactions did not differ from those of the normotensive patients. Nitrous oxide had no beneficial effect on the intubation response.

Ketamine anaesthesia for a patient with the Shy-Dräger syndrome.

A 58-year-old man with the Shy-Dräger syndrome underwent laryngo- and tracheoscopies in general anaesthesia for evaluation of the larynx after tracheostomy following bilateral vocal cord paralysis. A profound fall in arterial pressure during anaesthesia induced with thiopentone has been demonstrated in previously reported patients with the Shy-Dräger syndrome. In the present patient, anaesthesia induced with ketamine, maintained with nitrous oxide in oxygen and supplemented with fentanyl, diazepam and suxamethonium did not cause a fall in arterial pressure.

Attenuation of circulatory response to laryngoscopy and tracheal intubation: a comparison of two methods of topical anaesthesia.

Circulatory responses to laryngoscopy and endotracheal intubation were compared between three groups of patients, two of which were subjected to a procedure of topical anaesthesia before induction of general anaesthesia. Topical anaesthesia, achieved with either a lidocaine dose aerosol or by gargling with viscous lidocaine, attenuated the magnitude of the pressor response to laryngoscopy and intubation but had no effect on the heart rate response. Lidocaine aerosol had some advantages over viscous lidocaine; these were the significantly smaller haemodynamic response to the local anaesthetic procedure itself and probably shorter duration of the circulatory changes produced by intubation. It is concluded that both of these simple methods are relatively ineffective in preventing haemodynamic changes associated with laryngoscopy and intubation and should probably be combined with another preventive method.

Attenuation of the circulatory response to laryngoscopy and intubation by fentanyl.

The effects of fentanyl on arterial pressure and heart rate increases during laryngoscopy and intubation were studied in 45 normotensive, surgical patients, who were randomly allocated to three groups receiving 2 or 6 micrograms/kg of fentanyl or saline in a double-blind fashion before anaesthetic induction with thiopental. Fentanyl supplementation with 2 micrograms/kg significantly attenuated the arterial pressure and heart rate increases during laryngoscopy and intubation, and fentanyl, 6 micrograms/kg, completely abolished these responses. Moreover, fentanyl given during the induction decreased the amount of fentanyl needed during the operation. Respiratory depression was not observed during recovery.

Effects of precurarization on the blood pressure and heart rate changes induced by suxamethonium facilitated laryngoscopy and intubation.

The effects of precurarization on blood pressure and heart rate increases during laryngoscopy and intubation were studied in 60 surgical patients, who were randomly allocated to four groups, receiving as a pretreatment d-tubocurarine (0.05 mg/kg), alcuronium (0.03 mk/kg) , pancuronium (0.008 mg/kg) or saline in a double-blind fashion. d-Tubocurarine and alcuronium pretreatments seemed to attenuate the blood pressure increase during laryngoscopy and intubation under suxamethonium. Moreover, d-tubocurarine pretreatment protected effectively against high blood-pressure increases. Heart-rate increases were of the same magnitude in all the pretreated groups. d-Tubocurarine pretreatment abolished suxamethonium-induced fasciculations completely, whereas alcuronium pretreatment gave protection in 93% and pancuronium pretreatment in 43% of patients.