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VENTRICULAR ARRHYTHMIA OR SUPRAVENTRICULAR ARRHYTHMIA WITH ABERRANT CONDUCTION
BRITISH JOURNAL OF ANAESTHESIA
672 While Sigurdtson and his colleagues have devised » nice system for evaluating these arrhythmias, I believe that no discussion of arrhythmias during halotha&e anaesthesia is complete without documentation of arterial or end-tidal carbon itiA1"*^ In the absence of this information, it is not possible to implicate operative she or a given anaesthetic as the cause of the arrhythmia. I believe the most likely cause is the combination of hypercarbia, halothane and surgical stimulation. I agree that this frequent occurrence of ventricular arrhythmias is disturbing and that tracheal intubation during adenoidectomy is preferable. H.W.
KARL
Htrshty, Pennsylvania REFERENCES
Anaath., 55,861. Sir,—We agree with Dr Karl that the cause of the arrhythmiai was probably a combination of halothane, hypercarbia and surgical stimulus as we have ditniwri in other papers (Sigurdsson, 1983; Sigurdsson et al., 1983; Sigurdsson and Lindahl, 1983). These indiratcd that the occurrence of ventricular arrhythmias during halothane anaesthesia for adenoidectomy was halved by intubation and reduced even more with controlled ventilation. The purpose of the present ttudy (Sigurdsson, Werner and Fahraeus 1983) was more liming Recently, several authors (Alexander, 1971; Alexander, Bekbeit and Fletcher, 1972; Alexander and Murtagh, 1979; Lindgren, 1981) have suggested that widened QRS complexes occurring during oral surgery under halothane anaesthesia are usually aberrantly conducted supra ventricular impulses, rather than ventricular extrasystoles. However, the evidence has not been convincing and our study was carried out in order to gather further information regarding this specific question. G.H.
SIGURDSSON
Lund REFERENCES
Alexander, J. P. (1971). Dysrhythmia and oral surgery. Br. J.
Anaath., 43,773. Bekheh, S., and Fletcher, E. (1972). Dysrhythmia and oral surgery. II: Junctions] rhythms. Br. J. Anatsth., 44, 1179. Murtagh, J. G. (1979). Arrhythmia during oral surgery: Fasckular blocks in the cardiac conducting system. Br. J. Anatsth., 51,149. Lindgren, L. (1981). ECG changes during halnthane and enflurane anaesthesia for ENT surgery in children. Br. J.
Anatsth., 53,653.
thesiol.Scand.,n, 75. Lindahl, S. (1983). Cardiac arrhythmias in intubated children during adenoidectomy. A comparison between enflurane and halothane anaesthesia. ActaAnatsthtsiol. Scand., 27,484. Werner, O., and Fahraeus, T. (1983). Ventricular arrhythmia or (upraventricular arrythmia with aberrant conduction? An electrocardiographic study in halothane-anaesthetized children undergoing adenoidectomy. Br. J. Anatsth., 55, 861.
CHANGES IN RESIDUAL VOLUME FOLLOWING OXYGEN BREATHING
Sir,—With regard to the article by A. B. Baker and R. Restall (1983) entitled "Changes in residual volume following oxygen breathing", there is a discrepancy between the mean control FRC of 3.09±0.7 in table I and the FRC before oxygen breathing in table V of 3.18 ± 0.69. I have checked the mean and SD of FRC from the figues in table I and the mean and SD as quoted are correct. However, a paired Student's t test fails to demonstrate a significant reduction in FRC following oxygen breathing when FRC values in table I are compared with those in table IV. In addition, analysis of tables I and IV indicates that FRC increased after oxygen breathing in six and not five subjects, as quoted in table VI. Furthermore, would it not have been a preferable statistical method to have compared a change in FRC with CC using correlation/regression analysis, rather than comparing two FRC with CC using correlation/regression analysis, rather than comparing two groups by t test derived by retrospective classification based on the results? N.M.DEARDEN
Lttds REFERENCE
Baker, A. B., and Restall, R. (1983). Changes in residual volume following oxygen breathing. Br. J. Anatsth., 55, 817.
Sir,—Thank you for allowing me to reply to the correspondence from Dr Dearden. First, I am indebted to Dr Dearden for noticing a mistake in table I which had escaped my notice. The FRC value for the third subject R.C. should have read 3.90 litre instead of the 2.28 shown. The 2.28 was in fart the ERV (TLC) volume for R.C. and was inadvertently transcribed twice and not noticed. This corrects the meant SD for FRC in table I to 3.18 ±0.69, which is the correct value shown in table V. I regret this error, which occurred because we had two sets of independent statistical calculations for each author, and I did not notice the discrepancy in the final drafts. With this correct value for the FRC, the Students t test does demonstrate the values obtained in table V as stated in the article, so the conclusions remain the same. For the second point, only 18 (instead of 19) of the subjects were compared because we could not obtain a closing capacity for R.L., although we tried. Thus, although the FRC did increase in six subjects following oxygen breathing, we could compare only five of these with the 13 who decreased their FRC when considering the effects of closing capacity. This is clear from a study of
Downloaded from http://bja.oxfordjournals.org/ at Karolinska Institutet on July 30, 2015
Benumof, J. L. (1981). Respiratory physiology and respiratory function during anesthesia; in Antsthesia, Vol. 1 (ed. R. D. Miller), p. 120. New York: Churchill Livingstone. Karl, H. W., Swedlow, D. B., Lee K. W., and Downes, J. J. (1983). Epinephrine -halothane interactions in children. Antsthttiology, 58,142. Severinghaus, J. W., and Larson, C. P. (1965). Respiration in anesthesia; in Handbook of Physiology, Stction 3: Rtspiraaon, Vol. 2. (eds W. O. Fenn and H. Rahn), p. 1219. Baltimore: Williams and Wilkins. Sigurdsson, G. H., Werner, O., and Fahraeus, T. (1983). Ventricular arrhythmia or lupraventricular arrhythmia with aberrant conduction? An electrocardiographic study in halothaneanaesthetized children undergoing adenoidectomy. Br. J.
Sigurdsson, G. H.(1983). Enflurane and halothane anaesthesia in children. Cardiac arrhythmias and stress response during adenoidectomy. Doctoral thesis, University of Lund, Sweden. Carlsson, C , Lindahl, S., and Werner, O. (1983). Cardiac arrhythmias in non-intubated children during adenoidectoniy. A comparison between enflurane and halothane. Acta Anats-
672 While Sigurdtson and his colleagues have devised » nice system for evaluating these arrhythmias, I believe that no discussion of arrhythmias during halotha&e anaesthesia is complete without documentation of arterial or end-tidal carbon itiA1"*^ In the absence of this information, it is not possible to implicate operative she or a given anaesthetic as the cause of the arrhythmia. I believe the most likely cause is the combination of hypercarbia, halothane and surgical stimulation. I agree that this frequent occurrence of ventricular arrhythmias is disturbing and that tracheal intubation during adenoidectomy is preferable. H.W.
KARL
Htrshty, Pennsylvania REFERENCES
Anaath., 55,861. Sir,—We agree with Dr Karl that the cause of the arrhythmiai was probably a combination of halothane, hypercarbia and surgical stimulus as we have ditniwri in other papers (Sigurdsson, 1983; Sigurdsson et al., 1983; Sigurdsson and Lindahl, 1983). These indiratcd that the occurrence of ventricular arrhythmias during halothane anaesthesia for adenoidectomy was halved by intubation and reduced even more with controlled ventilation. The purpose of the present ttudy (Sigurdsson, Werner and Fahraeus 1983) was more liming Recently, several authors (Alexander, 1971; Alexander, Bekbeit and Fletcher, 1972; Alexander and Murtagh, 1979; Lindgren, 1981) have suggested that widened QRS complexes occurring during oral surgery under halothane anaesthesia are usually aberrantly conducted supra ventricular impulses, rather than ventricular extrasystoles. However, the evidence has not been convincing and our study was carried out in order to gather further information regarding this specific question. G.H.
SIGURDSSON
Lund REFERENCES
Alexander, J. P. (1971). Dysrhythmia and oral surgery. Br. J.
Anaath., 43,773. Bekheh, S., and Fletcher, E. (1972). Dysrhythmia and oral surgery. II: Junctions] rhythms. Br. J. Anatsth., 44, 1179. Murtagh, J. G. (1979). Arrhythmia during oral surgery: Fasckular blocks in the cardiac conducting system. Br. J. Anatsth., 51,149. Lindgren, L. (1981). ECG changes during halnthane and enflurane anaesthesia for ENT surgery in children. Br. J.
Anatsth., 53,653.
thesiol.Scand.,n, 75. Lindahl, S. (1983). Cardiac arrhythmias in intubated children during adenoidectomy. A comparison between enflurane and halothane anaesthesia. ActaAnatsthtsiol. Scand., 27,484. Werner, O., and Fahraeus, T. (1983). Ventricular arrhythmia or (upraventricular arrythmia with aberrant conduction? An electrocardiographic study in halothane-anaesthetized children undergoing adenoidectomy. Br. J. Anatsth., 55, 861.
CHANGES IN RESIDUAL VOLUME FOLLOWING OXYGEN BREATHING
Sir,—With regard to the article by A. B. Baker and R. Restall (1983) entitled "Changes in residual volume following oxygen breathing", there is a discrepancy between the mean control FRC of 3.09±0.7 in table I and the FRC before oxygen breathing in table V of 3.18 ± 0.69. I have checked the mean and SD of FRC from the figues in table I and the mean and SD as quoted are correct. However, a paired Student's t test fails to demonstrate a significant reduction in FRC following oxygen breathing when FRC values in table I are compared with those in table IV. In addition, analysis of tables I and IV indicates that FRC increased after oxygen breathing in six and not five subjects, as quoted in table VI. Furthermore, would it not have been a preferable statistical method to have compared a change in FRC with CC using correlation/regression analysis, rather than comparing two FRC with CC using correlation/regression analysis, rather than comparing two groups by t test derived by retrospective classification based on the results? N.M.DEARDEN
Lttds REFERENCE
Baker, A. B., and Restall, R. (1983). Changes in residual volume following oxygen breathing. Br. J. Anatsth., 55, 817.
Sir,—Thank you for allowing me to reply to the correspondence from Dr Dearden. First, I am indebted to Dr Dearden for noticing a mistake in table I which had escaped my notice. The FRC value for the third subject R.C. should have read 3.90 litre instead of the 2.28 shown. The 2.28 was in fart the ERV (TLC) volume for R.C. and was inadvertently transcribed twice and not noticed. This corrects the meant SD for FRC in table I to 3.18 ±0.69, which is the correct value shown in table V. I regret this error, which occurred because we had two sets of independent statistical calculations for each author, and I did not notice the discrepancy in the final drafts. With this correct value for the FRC, the Students t test does demonstrate the values obtained in table V as stated in the article, so the conclusions remain the same. For the second point, only 18 (instead of 19) of the subjects were compared because we could not obtain a closing capacity for R.L., although we tried. Thus, although the FRC did increase in six subjects following oxygen breathing, we could compare only five of these with the 13 who decreased their FRC when considering the effects of closing capacity. This is clear from a study of
Downloaded from http://bja.oxfordjournals.org/ at Karolinska Institutet on July 30, 2015
Benumof, J. L. (1981). Respiratory physiology and respiratory function during anesthesia; in Antsthesia, Vol. 1 (ed. R. D. Miller), p. 120. New York: Churchill Livingstone. Karl, H. W., Swedlow, D. B., Lee K. W., and Downes, J. J. (1983). Epinephrine -halothane interactions in children. Antsthttiology, 58,142. Severinghaus, J. W., and Larson, C. P. (1965). Respiration in anesthesia; in Handbook of Physiology, Stction 3: Rtspiraaon, Vol. 2. (eds W. O. Fenn and H. Rahn), p. 1219. Baltimore: Williams and Wilkins. Sigurdsson, G. H., Werner, O., and Fahraeus, T. (1983). Ventricular arrhythmia or lupraventricular arrhythmia with aberrant conduction? An electrocardiographic study in halothaneanaesthetized children undergoing adenoidectomy. Br. J.
Sigurdsson, G. H.(1983). Enflurane and halothane anaesthesia in children. Cardiac arrhythmias and stress response during adenoidectomy. Doctoral thesis, University of Lund, Sweden. Carlsson, C , Lindahl, S., and Werner, O. (1983). Cardiac arrhythmias in non-intubated children during adenoidectoniy. A comparison between enflurane and halothane. Acta Anats-