Anesth Analg 2000;90:231
© 2000 International Anesthesia Research Society
LETTERS TO THE EDITOR
Hemodynamic and Catecholamine Stress Responses to Insertion of the Combitube®, Laryngeal Mask Airway or Tracheal Intubation
Bernhard Panning, MD
Department of Anesthesiology and Intensive Care Medicine Medical School Hannover D-30625 Hannover, Germany
Fritz Sterz, MD
Department of Emergency Medicine University of Vienna A-1090 Vienna, Austria
The authors are to be congratulated for their meticulous work (1), because of it’s clinical importance for the already widespread use of the Combitube® (CT; Kendall-Sheridan Catheter Corp., Argyle, NY) in emergency situations. However, some of their findings, and especially their interpretations, raise major concerns.
First, we cannot follow the hypothesis in the introduction that insertion of the CT should "elicit higher serum levels of epinephrine and norepinephrine and a more pronounced hemodynamic reaction than the two other methods." All previously published articles do not support such an assumption (2,3). In contrast to the authors, we could not find a significant increase in blood pressure in our patients (4). We are specially wondering whether there was a statistically significant difference between CT versus endotracheal tube (ET) and laryngeal mask airway with respect to plasma epinephrine and norepinephrine concentrations (all values in pg/mL), e.g., mean epinephrine concentration 1 min after intubation is 34.7 ± 68.8 with ET versus 37.3 ± 31.1 with the CT, which is a difference of 2.6 pg/mL. This difference was even less at 5 min (35.8 ± 89.8 versus 35.2 ± 42.5), and turned around in disadvantage for the ET 10 min after intubation (32.6 ± 73 with the ET versus 24.8 ± 14.2 with CT), which, to our surprise, was found not to be statistically different. Furthermore, the standard deviations are very high; therefore, we doubt that there is any clinically relevant difference.
We are also wondering why there is no difference in heart rate as the first consequence to be expected after a significant increase of catecholamine levels. In addition, we do not believe that a difference in mean arterial pressure of 15 mm Hg (between ET and CT) is of any clinical importance. It would be of interest to show a correlation between plasma catecholamine levels and clinical observations.
The above mentioned major drawbacks of the paper don’t justify the conclusion "the increased stress response to insertion of a Combitube may represent a serious hazard to patients with cardiovascular disease." They may have been caused by a bias of the authors as stated in the hypothesis.
References
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Oczenski W, Krenn H, Dahaba AA, et al. Hemodynamic and catecholamine stress responses to insertion of the Combitube®, laryngeal mask airway or tracheal intubation. Anesth Analg 1999;88:1389–94.[Abstract/Free Full Text]
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Gaitini LA, Vaida SJ, Somri M, et al. Fiberoptic-guided airway exchange of the esophageal-tracheal Combitube® in spontaneously breathing versus mechanically ventilated patients. Anesth Analg 1999;88:193–6.[Abstract/Free Full Text]
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Mercer MH, Gabbott DA. The influence of neck position on ventilation using the Combitube® airway. Anaesthesia 1998;53:146–50.[Web of Science][Medline]
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Walz R, Davis S, Panning B. Is the Combitube® a useful emergency airway device for anesthesiologists [letter]? Anesth Analg 1999;88:233.[Free Full Text]
Response
Wolfgang Oczenski, MD
Department of Anesthesia and Intensive Care , Vienna City Hosiptal-Lainz , Vienna, Austria
Robert D. Fitzgerald, MD
Ludwig-Boltzmann Institute for Economics of Medicine in Anesthesia and Intensive Care , Vienna, Austria
With interest, we read the comments sent to you by Sterz F et al. concerning our article (1).
Certainly the critics named by the authors of this letter require some comments.
First, the authors of the letter state, that they cannot follow the hypothesis that we investigated: that if the Combitube® (CT; Kendall-Sheridan Catheter Corp., Argyle, NY) could elicit an endocrine stress response, it would lead to an elevation of serum catecholamine levels and a change in hemodynamics, as earlier publications (named in the letter) have shown this is not the case.
Stress responses during laryngoscopy, intubation, and insertion of different devices have been of interest to many anesthesiologists and are documented in numerous publications. Examples are referred to in our publication. The two studies named by the authors of the letter were published when our article was in the review process, respectively in the editing process, so they were unknown to us at the point of designing the protocol and writing the manuscript. However, although we studied the papers referred to by the authors of the letter carefully, we were unable to detect any data concerning hemodynamics or catecholamine levels in any of them. Thus, we still believe that our hypothesis is correct, the topic studied is of common interest, none of these questions were answered beforehand, and that no ‘bias in the hypothesis’ caused a fault in our conclusions.
Second, the authors state, that they were unable to verify an increase in blood pressure (they refer to a letter by Walz et al. (2) as described by us in our publication. Again, we studied the reference carefully, but were unable to find any data concerning the subject.
Furthermore, the authors of the letter point out that the differences in mean epinephrine blood levels are small, and they doubt there is a statistical difference between the groups endotracheal tube (ET) and CT. As stated in our methods section, significances were calculated by means of a Kruskall-Wallis test, followed by a Mann-Whitney U-Test and resulted in the findings reported in the publication. However, we acknowledge, that given the non normal distribution of the data, it might have been preferable to present the data as median ± SE rather than as mean ± SD. Thus, we supply the data in question as median ± SE (Table 1).
Regarding the lack of difference in heart rate, we would like to draw attention to the fact that the increase in norepinephrine was far greater than the increase in epinephrine. Thus, we explain the lack of an increase of heart rate by the predominantly  -adrenergic action of norepinephrine.
Furthermore, the authors of the letter believe, that the difference of 15 mm Hg in mean arterial blood pressure (between ET and CT) is without any clinical importance. This number might seem small. However, the difference in mean systolic blood pressure between these groups (reported in the summary) were 160 ± 32 mm Hg in the CT group, vs 140 ± 24 in the ET group. We believe that most anesthesiologists would regard this as a clinical important difference in patients at risk of hypertensive bleeding and would either avoid procedures leading to such an increase or include countermeasures in their management, when the procedure is inevitable. Also, we want to emphasize, that any stress-related change in hemodynamic parameters is subject to the amount of anesthesia and analgesia supplied to the patient. In our study, we followed a standardized procedure routinely used for this kind of surgery in our institution and very comparable to those used by others in clinical routine and research. Nevertheless, we had a significant increase in systemic arterial pressure, mean arterial pressure, and diastolic augmentation pressure in the patients undergoing insertion of the CT. However, as it is much more difficult to apply such a carefully dosed regimen in emergency situations; increases of blood pressure might be even more pronounced in such patients.
References
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Oczenski W, Krenn H, Dahaba AA, et al. Hemodynamic and catecholamine stress reponses to insertion of the Combitube®, laryngeal mask airway, or tracheal intubation. Anesth Analg 1999;88:1389–94.
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Walz R, Davis S, Panning B. Is the Combitube® a useful emergency airway device for anesthesiologist [letter]? Analg 1999;88;233.
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