Experimental paperImpairment of carotid artery blood flow by supraglottic airway use in a swine model of cardiac arrest☆
Introduction
For many years endotracheal intubation (ETI) has been the gold standard for ventilation by advanced life support personnel during cardiopulmonary resuscitation (CPR).1 Recently, supraglottic airway devices (SGDs) have been promoted as an alternative to endotracheal intubation for patients undergoing CPR.1 The supraglottic airway devices can be placed ‘blindly’ and rapidly, without the need to stop chest compressions.2, 3 The benefits of not stopping chest compressions during CPR have been well recognized, and consequently, supraglottic airway devices have become popular, especially for patients with out-of-hospital cardiac arrest.4
Despite this recent shift in airway management practice, little is known about the potential effects of supraglottic airways on cardiovascular hemodynamics.5 Anatomically, the carotid arteries track inside a relatively non-distensible sheath in the median portion of the neck, adjacent to the laryngeal and pharyngeal space. As such, any increase in pressure in the retropharyngeal space could be theoretically transmitted to the carotid arteries and reduce carotid blood flow. In this study we examined the hypothesis that use of a supraglottic airway adjuncts in pigs undergoing CPR will result in compression of the carotid arteries, thereby reducing cerebral blood flow.
Section snippets
Methods
The study was approved by the Institutional Animal Care Committee of the Minneapolis Medical Research Foundation of Hennepin County Medical Center.
Results
The goal of our study was to compare carotid blood flow during CPR with an endotracheal tube and three different supraglottic airways. There were statistically significant reductions in carotid blood flow with all supraglottic airway adjuncts when compared with an endotracheal tube, as shown in Table 1 and Fig. 1, Fig. 2. As shown in the representative tracing from one study in Fig. 1, the changes in carotid blood flow occurred instantaneously with placement and removal of each airway adjunct.
Discussion
Results from this study in pigs suggest that there may be unanticipated consequences of using supraglottic airway devices in the management of patients in low-flow states such as cardiac arrest. The results support the hypothesis that use of supraglottic devices has the potential, at least in pigs, to impair carotid flood flow during CPR when there is already a decrease is vital organ perfusion. The mechanism appears to be secondary to an increase in supraglottic pressure with compression of
Conclusion
In pigs undergoing CPR, use of supraglottic airway device originally designed for human use was associated with a significant reduction in carotid blood flow when compared with an endotracheal tube. These new findings in pigs suggest that further research on the effects of supraglottic airway device use in humans and their potential effects on carotid artery blood flow is warranted.
Conflict of interest statement
None.
Contributors
All authors have participated to the conception, design and writing of this manuscript.
Funding source
The study was funded by an Institutional, Division of Cardiology grant at the University of Minnesota to Dr. Yannopoulos.
Ethical approval
The study was approved by the Institutional Animal Care Committee of the Minneapolis Medical Research Foundation of Hennepin County Medical Center, and all animals received treatment in compliance with the National Research Council's 1996 Guide for the Care and Use of Laboratory Animals.
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A Spanish translated version of the abstract of this article appears as Appendix in the final online version at http://dx.doi.org/10.1016/j.resuscitation.2012.03.025.