Br.J. Anaesth. (1978), 50, 1243

CARDIAC ARRHYTHMIAS DURING OUTPATIENT DENTAL ANAESTHESIA: A COMPARISON OF CONTROLLED VENTILATION WITH AND WITHOUT HALOTHANE V. J. E. THOMAS, K. P. KYRIAKOU AND A. C. THURLOW SUMMARY

The frequency and nature of cardiac arrhythmia during two controlled ventilation techniques for endotracheal anaesthesia in dental outpatients have been compared. Both techniques used nitrous oxide and oxygen with alcuronium, but in one the additional agent was halothane and in the other it was fentanyl. The frequency of arrhythmia in both groups was 5%. No ventricular arrhythmia was seen but benign nodal rhythm was noted. It is suggested that the anti-arrhythmia effect of nondepolarizing muscle relaxants may prevent ventricular arrhythmia in patients receiving halothane.

V. J. E. THOMAS, F.F.A.R.C.S. ; K. P. KYRIAKOU, F.F.A.R.C.S. ; A. C. THURLOW, F.F.A.R.C.S., Department of Anaesthetics,

St George's Hospital, London S.W.17. Correspondence to V. T., 67 Queen's Road, London SW14. 0007-0912/78/0050-1243 $01.00

ventilated artificially, but one received halothane and the other received fentanyl. METHOD

Ninety-two patients attending the outpatient department of the Royal Dental Hospital, Tooting, for dental extractions under general anaesthesia were studied. All were fit and free from cardiovascular or respiratory disease. Their ages ranged from 10 to 48 years. There were two groups by previous random selection, receiving either halothane (group A, 53 patients) or fentanyl (group B, 39 patients). The groups were similar in respect of age, weight and sex distribution. No premedication was given and all patients were anaesthetized in the dental chair in a 45° head-up tilt with the legs elevated. The patients in group A were anaesthetized with thiopentone 5-6 mg kg" 1 i.v., followed by alcuronium 10-15 mg, and anaesthesia was maintained with 0.5% halothane in 66% nitrous oxide in oxygen (3 litre m k r 1 ) with intermittent positive pressure ventilation (IPPV). The patients in group B were anaesthetized with fentanyl 1.0 ng kg" 1 i.v., followed by thiopentone 5 - 6 m g k g - 1 and alcuronium 10-15 mg; anaesthesia was maintained with 66% nitrous oxide and oxygen with IPPV. In all patients the trachea was intubated with a cuffed nasotracheal tube and the throat was packed. Alcuronium was antagonized at the end of the procedure with neostigmine 2.5-5.0 mg with atropine 1.2-1.8 mg i.v. Gases were delivered from a Salisbury continuous flow machine and ventilation was controlled with an Autovent (East) miniature ventilator. © Macmillan Journals Ltd 1978

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A high frequency of cardiac arrhythmia during anaesthesia for dental surgery is usual (Kaufman, 1966; Tolas et al., 1967; Tuohy, 1968; Rollason and Dundas, 1970; Alexander, 1971; Ryder, 1971; Thurlow, 1972). Halothane has been implicated as a major factor in this because it sensitizes the myocardium to catecholamines (Katz and Bigger, 1970). The frequency of arrhythmia has been reduced by blocking afferent surgical stimuli with local anaesthetic agents (Plowman, Thomas and Thurlow, 1974), by giving prophylactic (3-blockers (Tolas and Allen, 1970; Rollason and Hall, 1973), or by avoiding the use of halothane (Shafto, 1969; Rollason and Dundas, 1970; Ryder and Townsend, 1974; Thomas, Thomas and Thurlow, 1976). The frequency of arrhythmia in dental outpatients breathing spontaneously nitrous oxide in oxygen and halothane through a tracheal tube has been compared with that during controlled ventilation with nitrous oxide in oxygen in patients who had received tubocurarine and fentanyl (Thomas, Thomas and Thurlow, 1976). It was found that surgically induced arrhythmia was absent in 50. patients receiving fentanyl as compared with a frequency of 34% in patients breathing halothane spontaneously. This difference was attributed to the absence of halothane rather than the use of intermittent positive pressure ventilation (IPPV). In order to confirm this, two further groups were studied: in both the lungs were

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mia was predominantly ventricular extrasystole, often multifocal in origin. This finding was similar to other published work (Kaufman, 1966; Tuohy, 1968; Ryder, 1971; Thurlow, 1972). The dramatic reduction in this frequency when IPPV, nitrous oxide in oxygen, tubocurarine and fentanyl were used, was attributed to the absence of halothane. The present study used two identical techniques of IPPV except that in one group halothane was substituted for fentanyl. However, there was a low frequency of surgically induced cardiac RESULTS arrhythmias in both groups. Thus, halothane per se is In group A, nine patients developed an arrhythmia not the factor producing arrhythmia; it is the (17%), three of which were induced by surgery combination of halothane and spontaneous ventilation. (5.6%), the remainder being associated with intubaThis raises the possibility that increased PaCOtmav tion and packing (table I). be the important factor in the presence of halothane. Certainly, fit patients undergoing IPPV have low to normal P&co2- However, other studies on unTABLE I. Frequency of cardiac arrhythmia premedicated dental outpatients (Tolas et al., 1967), Group A Group B have shown that Pac 02 is essentially normal when the patient breathes spontaneously. Furthermore, Black 53 39 Number of patients 9 5 and others (1959) showed that the threshold P a ^ Numbers showing arrhythmia 6 2 Arrhythmia during intubation for cardiac arrhythmia under halothane anaesthesia and packing was in excess of 8 kPa. 3 2 Arrhythmia during surgery A factor reducing the frequency of arrhythmia may 0 1 Other arrhythmia be the use of non-depolarizing myoneural blockade. Non-depolarizing muscle relaxants have been shown In group B, five patients developed an arrhythmia to have anti-arrhythmia properties, in particular to (13%); two were induced by surgery (5.1%), two protect against ventricular arrhythmia induced by associated with intubation and packing (5.1%). One catecholamines. The probable mechanism of action is patient developed brief nodal rhythm after antagonism by depression of cardiac nerve terminals, thereby of alcuronium with neostigmine and atropine. increasing the threshold of excitation, or decreasing The frequency of surgically induced arrhythmia in automaticity of cardiac cells or both (Wong et al., the two groups was of the same order. Only nodal 1971). rhythms occurred and these were of normal rate and There is the possibility that blood concentrations not associated with any reduction in arterial pressure. of halothane, and consequently depth of anaesthesia, No ventricular extrasystole was seen during surgery. differed between spontaneously breathing and ventiThe frequency of arrhythmia associated with lated groups. Ryder (1970) showed that ectopic intubation and packing was less in the group which rhythms were abolished when dental anaesthesia with received fentanyl (5.1% as opposed to 11.3%), but halothane was deepened; only nodal rhythms were this difference was not statistically significant. seen. This is exactly what occurred when our patients' Arrhythmia on intubation was predominantly ventri- lungs were ventilated with 0.5% halothane, supportcular extrasystole (six patients); in two patients this ing the possibility that they were at a deeper level of was monofocal, and in four multifocal in origin. In anaesthesia than those breathing 1-2% halothane two patients nodal rhythm was seen. spontaneously. Measurement of blood concentrations of halothane in the two groups would be necessary to confirm this. It may be that the ability to deepen DISCUSSION anaesthesia without concurrently increasing carbon In a previous study of spontaneous ventilation with dioxide concentrations when using halothane with nitrous oxide, oxygen and halothane, the frequency of controlled ventilation is an important contributing surgically induced cardiac arrhythmia was 34% factor in the reduction of surgically induced arrhyth(Thomas, Thomas and Thurlow, 1976). The arrhyth- mia. The e.cg. was monitored throughout, using Standard lead I via an oscilloscope (Wakeling, BOC) connected in series. with an electrocardiograph (Cardiopan, Philips). Monitoring was commenced before induction and any arrhythmia was recorded. Arterial pressure was measured using an oscillotonometer and recorded, with the heart rate, before operation and at 5-min intervals throughout the procedure.

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CONTROLLED VENTILATION AND ARRHYTHMIA IN DENTISTRY ACKNOWLEDGEMENTS

The authors wish to thank Professor G. L. Howe and Mr J. F. Towers for permission to study their patients. They also wish to thank Dr J. G. B. Thurston, Senior Registrar in Cardiology at the Westminster Hospital, for interpreting the electrocardiograms.

REFERENCES

ARYTHMIES CARDIAQUES PENDANT LES ANESTHESIES DENTAIRES SUR DES PATIENTS DE CONSULTATION EXTERNE: COMPARAISON DE LA VENTILATION CONTROLEE AVEC OU SANS HALOTHANE RESUME

On a compart la frequence et la nature de l'arythmie cardiaque pendant l'application de deux techniques de ventilation controlee utilis6es pour l'anesthdsie endotracheale sur des patients recevant des soins dentaires en consultation externe. Ces deux techniques etaient basdes sur le protoxyde d'azote et l'oxygene avec alcuronium, mais dans l'une d'elles l'agent supplementaire etait l'halothane et dans Pautre, le fentanyl. La frequence de l'arythmie dans les deux groupes a ete de 5%. On n'a vu aucune arythmie ventriculaire, mais on a remarqu6 un rythme nodal benin. Tout laisse penser que Peffet d'anti-arythmie des decontracturants musculaires non d£polarisants peut empecher Parythmie ventriculaire chez les malades recevant de l'halothane.

KARDIAKARRHYTHMIE WAHREND ANASTHESIE BEI AMBULANTER ZAHNBEHANDLUNG: EIN VERGLEICH ZWISCHEN KONTROLLIERTER VENTILATION . MIT UND OHNE HALOTHAN ZUSAMMENFASSUNG

Die Art und Haufigkeit von Kardiakarrhythmien wahrend zweier kontrollierten Ventilationsmethoden fiir endotracheale Anasthesie wurden in ambulanten Zahnpatienten verglichen. Beide Methoden benutzten Stickstoffoxydul und Sauerstoff mit Alcuronium, aber im einen Fall war das zugesetzte Agens Halothan, im anderen Fentanyl. Die Haufigkeit der Arrhythmie war in beiden Gruppen 5%. Es wurde keine ventrikulare Arrhythmie beobachtet, aber ein gutartiger Knotenrhythmus wurde festgestellt. Es wird angenommen, dass die antiarrhythmische Wirkung der nicht-depolarisierenden, muskelentspannenden Mittel eine ventrikulare Arrhythmie in Patienten mit Halothan verhindert.

ARRITMIA CARDIACA DURANTE ANESTESIA DENTAL EN PACIENTES DE CONSULTORIO: UNA COMPARACION ENTRE VENTILACION CONTROLADA CON Y SIN HALOTANO SUMARIO

Se ha comparado la frecuencia y naturaleza de arritmia cardiaca entre dos ticnicas de ventilaci6n controlada para anestesia endotraqueal en pacientes de consultorio dental. Ambas tecnicas se valieron de oxido nitroso y oxigeno con alcuronio, pero en uno el agente adicional fue halotano y en el otro, fentanil. La frecuencia de arritmia en ambos grupos fue de 5%. No se not6 arritmia ventricular, pero si un ritmo nodal benigno. Se sugiere que el efecto de antiarritmia de los relajantes musculares no depolarizantes puede evitar arritmia ventricular en los pacientes que reciben halotano.

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Alexander, J. P. (1971). Dysrhythmia and oral surgery. Br.J. Anaesth., 43,773. Black, G. W., Linde, H. W., Dripps, R. D., and Price, H. L. (1959). Circulatory changes accompanying respiratory acidosis during halothane anaesthesia in man. Br. J. Anaesth., 31,238. Katz, R. L., and Bigger, J. T. (1970). Cardiac arrhythmias during anesthesia and operation. Anesthesiology, 33, 193. Kaufman, L. (1966). Cardiac arrhythmias during dental anaesthesia. Proc. R. Soc. Med., 59,731. Plowman, P. E., Thomas, W. J. W., and Thurlow, A. C. (1974). Cardiac dysrhythmias during anaesthesia for oral surgery: the effect of local blockade. Anaesthesia, 29, 571. Rollason, W. N., and Dundas, C. R. (1970). Incidence of cardiac arrhythmia during dental anaesthesia; in Progress in Anaesthesiology, Proceedings of the Fourth World Congress of Anaesthesiologists, London, 1968, p. 969. Excerpta Medica International Congress Series No. 200. Hall, D. J. (1973). Dysrhythmias during inhalational anaesthesia for oral surgery: incidence and prevention and treatment with practolol. Anaesthesia, 28,139. Ryder, W. (1970). The electrocardiogram in dental anaesthesia. Anaesthesia, 25,63. (1971). Cardiac rhythm during dental anaesthesia. Proc. R. Soc. Med., 64,82. Townsend, D. (1974). Cardiac rhythm in dental anaesthesia: a comparison of five anaesthetic techniques. Br.J. Anaesth., 46,760. Shafto, C. E. (1969). Continuous intravenous anaesthesia : for paediatric dentistry. Br.J. Anaesth., 41,407. Thomas, V. J. E., Thomas, W. J. W., and Thurlow, A. C. (1976). Cardiac arrhythmia during outpatient dental anaesthesia: the advantages of a controlled ventilation technique. Br.J. Anaesth., 48,919. Thurlow, A. C. (1972). Cardiac dysrhythmias in outpatient dental anaesthesia in children: the effect of prophylactic intravenous atropine. Anaesthesia, 27,429. Tolas, A. G., and Allen, G. D. (1970). Propanolol in preven. tion of cardiac arrhythmia. J. Oral Surg., 28,181. Ward, R. J., Kennedy, W. T., and Bonica, J. J. (1967). Comparison of effects of methods of induction of anaesthesia on cardiac rhythm. J. Oral Surg., 25,54. Tuohy, O. (1968). Cardiac arrhythmias during oral surgical procedures. Br. Dent.J., 124,417. Wong, K. C , Wyte, S. R., Martin, W. E., and Crawford, E. W. (1971). Antiarrhythmic effects of skeletal muscle relaxants. Anesthesiology, 34,458.

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Cardiac arrhythmias during outpatient dental anaesthesia: a comparison of controlled ventilation with and without halothane.

Br.J. Anaesth. (1978), 50, 1243 CARDIAC ARRHYTHMIAS DURING OUTPATIENT DENTAL ANAESTHESIA: A COMPARISON OF CONTROLLED VENTILATION WITH AND WITHOUT HAL...
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