Is the Combitube a useful emergency airway device for anesthesiologists?

Abstract

The Combitube[trade mark sign] (Kendall Sheridan Catheter Corp., Argyle, NY) is an emergency airway device designed primarily for situations in which endotracheal intubation is not immediately possible [1,2]. Although some authors suggest that the Combitube[trade mark sign] is relatively easy to place, that claim either has come from the home institution of its inventor or has included the inventor's assistance with the study [1,3]. Practitioners in those studies were likely to have had preexisting familiarity with the device. We hypothesized that the Combitube[trade mark sign] could be successfully used by anesthesiologists who were aware of the device but with no prior clinical experience with it. Methods The study was conducted at the University of Washington Medical Center and the Puget Sound Veterans Affairs Medical Center. ASA physical status I or II patients provided their written consent, and the study was approved by the human subjects committees of both institutions. The physician responsible for intubation in all cases was either an attending anesthesiologist or an anesthesiology resident. Residents were either third- or first-year residents who had completed at least 6 mo of training. All had been instructed in the theory of the Combitube[trade mark sign] as part of a difficult airway algorithm. The theory and placement instructions per the package insert were reviewed briefly with the physician responsible for intubation just before induction. Anesthesia was induced with 5 mg/kg thiopental, and muscle relaxation was achieved with 1 mg/kg succinylcholine. Physicians were instructed to attempt a blind placement first, and then to use a laryngoscope if they thought that blind placement had failed. The decision to use the laryngoscope was made only if repeated resistance to intubation was met. Intubations were rated by one of the authors as "first pass," "requiring multiple blind attempts," "requiring laryngoscope," or "failed." Results The Combitube[trade mark sign] was successfully placed in the esophagus of 15 of 16 patients. In 1 patient, the tube could not be placed in the esophagus even using a laryngoscope, and no attempt was made to place it in the trachea. The degree of difficulty encountered was variable (Figure 1), with first-pass blind placement resulting in only 6 of the 16 patients.Figure 1: Difficulty in placement of the Combitube[trade mark sign].In all patients in whom the Combitube[trade mark sign] was placed, ventilation was easily established, with the exception of one patient who developed severe bronchospasm. Discussion The Combitube[trade mark sign] is an effective means of ventilating patients in cases of cardiac arrest [1], but there has been little evaluation of its ease of placement by anesthesiologists. The original description of the device noted esophageal placement in 23 of 24 patients, with tracheal placement in the final patient [1]. No mention was made of failure to place the tube in either the esophagus or the trachea, nor was mention made of a requirement for a laryngoscope in any patient. In a study performed in 1993 in which nurses were trained using a mannequin, the authors noted that the tube was placed successfully in 16 of 17 patients [3]. This study was conducted at the home institution of the designers of the tube; hence, the results may have been affected by the trainees' familiarity with it [3]. A study of Combitube[trade mark sign] placement by paramedics performed at an institution unaffiliated with the designers found that it was inserted successfully only 71% of the time when used as a first-line airway adjunct, and 64% of the time in patients who could not be intubated with an endotracheal tube using direct laryngoscopy [4]. A follow-up study of the paramedics conducted 15 mo later demonstrated inadequate skill retention. We were concerned that although the Combitube[trade mark sign] is included as an option in the ASA difficult airway algorithm, most anesthesiologists would have little experience with it before their first emergent use. Hence, we studied whether staff previously instructed in the use of the tube could use it after a brief reminder, such as would be obtained from the package insert. We found that the device could provide an airway in almost all patients but that first-pass success without a laryngoscope occurred in only 38% of the patients. The increased success with the aid of a laryngoscope was remarkable. After completing the study, we found, in a textbook, a recommendation from the designer of the tube suggesting that a laryngoscope often helped with placement [5]. Based on our results, we would support this recommendation and encourage the manufacturer to include it in the package insert. We conclude that the Combitube[trade mark sign] can be placed by anesthesiologists with relatively little formal training. However, we recommend that a laryngoscope be used to assist with placement if the first pass is not successful and further suggest that this advice be added to the package insert.