Title: Hemodynamic and Catecholamine Stress Responses to Insertion of the Combitube®, Laryngeal Mask Airway or Tracheal Intubation
Abstract: 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. Bernhard Panning MD Fritz Sterz MD