Clinical data support the non-inferiority of continuous chest compressions compared with conventional cardiopulmonary resuscitation
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December 13, 2007 By Benjamin A. Olenchock, M.D. Ph.D. [1]
Stockholm and Kyoto
Just over one month ago, Wikidoc reported the results of a study demonstrating that continuous chest compressions were superior to the AHA-recommended 30:2 chest compressions to rescue breaths. That study used a swine model of cardiopulmonary resuscitation (CPR), and demonstrated improved neurologically normal survival in pigs randomized to continuous chest compressions. Now, new clinical data from two separate studies suggest that people are very similar to pigs.
One study used the Swedish Cardiac Arrest Registry, and examined outcomes of 11,275 patients who received bystander CPR, 10% of whom received continuous chest compressions without rescue breaths. The minority of patients who received chest compressions only were on average older (mean age 66 vs. 63, p<0.0001) and had a shorter time until ambulance arrival (6 min vs. 8 min). The authors examined outcomes in the two groups, adjusting for confounders including age, sex, time, and the type of bystander. Patient co-morbidity data was not available, however. Survival to the hospital (19.5% vs. 20%) and at 1-month (7.2 vs. 6.7; adjusted OR 1.18 [0.89-1.56]) were similar between the patients treated with conventional CPR and those who received continuous chest compressions, respectively. This trial was not randomized, and it there is no data regarding the reasons why bystanders initiated continuous chest compression CPR instead of the recommended method. As the authors note, fear of acquiring an infection through providing ventilatory support might have influenced the decisions. Interestingly, while only 10% of patients received continuous chest compressions, 17% of patients received rescue breath-only resuscitation. These patients were younger, were more likely to be female, and were less likely to survive to the hospital or to 1-month most event (4.5% 1-month survival, p<0.0001 compared to standard CPR).
The second study, published concurrently in the journal Circulation, was a prospective study from Kyoto Japan, where chest compression only bystander resuscitation is more common, perhaps for cultural reasons. The authors compared outcomes after out of hospital cardiac arrests in 783 individuals who received conventional CPR with 544 individuals who received chest compressions only. In this study, 1-year survival was better in the chest compression only group (4.3% vs. 2.5%, OR 1.72 [1.01 to 2.95]), but only for resuscitations lasting less than 15 minutes. For longer resuscitations, outcomes were poor regardless, however there was a significant improvement in outcomes in the conventional CPR group (0% vs. 2.2%, p<0.05)
The 2005 AHA guidelines for CPR changed the recommended ratio of chest compressions to ventilations from 15:2 to 30:2, emphasizing the greater importance of circulatory support. Small clinical trials and experimental animal models suggest that continuous chest compressions without rescue breaths might be a simpler, more user-friendly method of CPR that can achieve similar results. The long delay in circulatory support during administration of rescue breaths is one problem with the currently recommended CPR method, as is rescuer discomfort with mouth-to-mouth resuscitation.
On-going randomized trials in the USA and in Sweden will help settle the question of which resuscitation method is superior. If continuous chest compressions are found to be equivalent, there appear to be good reasons to adopt this method of resuscitation.
1. Ewy GA, Zuercher M, Hilwig RW, Sanders AB, Berg RA, Otto CW, Hayes MM, Kern KB. Improved neurological outcome with continuous chest compressions compared with 30:2 compressions-to-ventilations cardiopulmonary resuscitation in a realistic swine model of out-of-hospital cardiac arrest. Circulation. 2007 Nov 27;116(22):2525-30. Epub 2007 Nov 12.
2. Katarina Bohm, Mårten Rosenqvist, Johan Herlitz, Jacob Hollenberg, and Leif Svensson Survival Is Similar After Standard Treatment and Chest Compression Only in Out-of-Hospital Bystander Cardiopulmonary Resuscitation. Circulation 2007: published online before print December 10, 2007, 10.1161/CIRCULATIONAHA.107.710194.
3. Taku Iwami, Takashi Kawamura, Atsushi Hiraide, Robert A. Berg, Yasuyuki Hayashi, Tatsuya Nishiuchi, Kentaro Kajino, Naohiro Yonemoto, Hidekazu Yukioka, Hisashi Sugimoto, Hiroyuki Kakuchi, Kazuhiro Sase, Hiroyuki Yokoyama, and Hiroshi Nonogi Effectiveness of Bystander-Initiated Cardiac-Only Resuscitation for Patients With Out-of-Hospital Cardiac Arrest Circulation 2007: published online before print December 10, 2007, 10.1161/CIRCULATIONAHA.107.723411.
