Literature Review: Advanced Airways in Cardiac Arrest
Nagao T, Kinoshita K, Sakurai A, et al. Effects of bag-mask versus advanced airway ventilation for patients undergoing prolonged cardiopulmonary resuscitation in prehospital setting. J Emerg Med, Oct 25, 2011 [e-pub ahead of print].
The aim of this study was to compare advanced airway ventilation (AAV) to bag-mask ventilation (BMV) for cardiopulmonary arrest (CPA) patients in the prehospital setting. Methods—Patients who suffered out-of-hospital cardiogenic CPA from 2006 to 2007. The primary endpoint was a favorable neurological outcome; the secondary endpoints were rate of return of spontaneous circulation (ROSC) and rate of admission to the intensive care unit (ICU). Results—355 CPA patients (156 BMV and 199 AAV) were enrolled. There was no significant difference in demographics between the two groups. Transportation time exceeded 30 minutes in both groups. The overall ROSC rate and ICU admission rate were significantly higher in the AAV group. AAV resulted in a higher overall ROSC rate than BMV, but there were no significant differences in either the rate of ROSC or in favorable neurological outcome. Conclusion—AAV may yield advantages over BMV in the overall rate of ROSC in CPA patients, but both approaches for airway management in this study resulted in a comparably favorable neurological outcome.
Kajino K, Iwami T, Kitamura T, et al. Comparison of supraglottic airway versus endotracheal intubation for the prehospital treatment of out-of-hospital cardiac arrest. Crit Care 15(5): R236, Oct 10, 2011 [e-pub ahead of print].
All adults with witnessed non-traumatic OHCA, from January 1, 2005 to December 31, 2008, treated by EMS with an advanced airway in Osaka, Japan were studied. The primary outcome measure was one-month survival with neurologically favorable outcome. The association between type of advanced airway (ETI/SGA), timing of device placement and neurological outcome was assessed by multiple logistic regression. Results—Of 7,517 witnessed non-traumatic OHCAs, 5,377 cases were treated with advanced airways. Of these, 1,679 were ETI, while 3,698 were SGA. Favorable neurological outcome was similar between ETI and SGA (3.6% versus 3.6%). The time interval from collapse to ETI placement was significantly longer than for SGA (17.2 minutes versus 15.8 minutes). Early placement of an advanced airway was significantly associated with better neurological outcome (adjusted odds ratio [AOR] for one minute delay, 0.91). ETI was not a significant predictor but presence of an ETI-certified ELST (emergency lifesaving technician; AOR, 1.86) was a significant predictor for favorable neurological outcome. Conclusions—There was no difference in neurological favorable outcome from witnessed OHCA for ETI versus SGA. Early airway management with advanced airway regardless of type and rhythm was associated with improved outcomes.
These two studies from Japan illustrate just how much more we need to know before we can decide on the best approach to airway management in cardiac arrest. In the first, from Tokyo, patients on whom advanced airway ventilation was used had an increased rate of ROSC but not hospital discharge. Although there was a trend toward better overall survival in the SGA patients (4% AAV vs. 3.2% BVM—a 25% increase), the total of 13 survivors was too low to make that difference statistically significant. Another limitation was that authors bundled together the Combitube, LMA and endotracheal intubation, three very different airways, into the AAV group. One interesting finding was that even with relatively long transport times (greater than 30 minutes), BVM results were roughly equivalent to AAV.
In the second, much larger study from Osaka, patients treated with endotracheal intubation had the same survival rate as those with supraglottic airways. Survival rates were higher with earlier insertion of advanced airways and in patients treated by advanced EMTs (minimum 2 years training) regardless of which airway was used, which suggests that experience and proficiency in airway management are important contributors to improved outcomes.
These studies are more important in pointing out the significant gaps in our knowledge of airway management in cardiac arrest. Prospective controlled studies are needed to give us more information on which (if any) airway (BVM, supraglottic, ETI), when, by whom and with what training and experience might best be used on given patients.