Every day more than 917 Americans die from cardiac arrest, which usually results from a sudden ]]>heart attack]]> . Whether this occurs inside or outside a hospital setting, early cardiopulmonary resuscitation (CPR) and defibrillation (with electrically charged paddles) can significantly increase the chance of survival.

CPR is a technique that uses a combination of chest compressions and mouth-to-mouth breathing (ventilation) to try and maintain heart and lung functioning. By supporting a small amount of blood flow to the heart, brain, and other vital organs, CPR can potentially buy time until normal heart function is restored with definitive treatment.

Studies suggest that in addition to timely CPR, the quality of CPR performance can also influence patient outcome. Specifically, chest compressions appear to be the most important factor, with even short interruptions having a negative impact on survival. Not much is known, however, about the actual quality of CPR performance provided by medical personnel as compared to international guidelines.

Two new studies in the January 19, 2005 issue of the Journal of the American Medical Association examine the quality of CPR performed by trained medical personnel: one looking at out-of-hospital CPR and the other at in-hospital CPR. This article will focus on the first study, which measured the quality of out-of-hospital CPR performed by ambulance personnel.

About the Study

The first study included 176 adults who were treated for cardiac arrest by ambulance personnel in three different cities; Akershus, Norway; Stockholm, Sweden; and London, England. To carry out this study, researchers equipped six ambulances in each of the three regions with prototype defibrillators. These defibrillators were fitted with a pressure sensor to measure chest compression depth, in addition to standard equipment to record the electrical activity of the heart.

Right before the study period began, all involved medical personnel underwent a refresher course in advanced cardiac life-support according to international guidelines. The researchers informed the personnel that they would be studying CPR performance and recording chest compressions—but not that a primary focus of the study was the duration of time that CPR was performed. The study period lasted from March 2002 to October 2003.

The second study used the same monitoring device to measure CPR performance on 67 patients who experienced cardiac arrest while in a University of Chicago Hospital between December 2002 and April 2004.

The primary outcome measure for both studies was adherence to the international guidelines for CPR including: compression rate (target: 100 per minute to 120 per minute); depth (target 38-52 millimeters); and ventilation rate (target: two ventilations for every 15 compressions).

The Findings

CPR performance was not up to standards in either of the studies. In the first study, the average compression rate was 121 per minute, however ambulance personnel did not provide chest compressions for 48% of the time. Therefore, the actual compression rate averaged only 64 per minute—well below the target range. The average compression depth was 34 millimeters, also below the target range. An average of 11 ventilations were given per minute.

In the second study, patients did not receive chest compressions 24% of the time. Additionally, chest compression rates were less than 90 per minute 28% of the time, and compression depth was too shallow (below the target range of 38-52 millimeters) 37% of the time. The researchers also found that ventilation rates were high: greater than 20 per minute 61% of the time.

How Does This Affect You?

These studies found that the quality of real world CPR performance—by trained medical personnel—often falls short of the recommended standards.

What these studies cannot say is whether or not these substandard practices save fewer lives. The fact that the results held true regardless of the location and setting of the cardiac arrest, suggests that the problem may lie with the guidelines and not with the medical personnel. An accompanying editorial points out that the guidelines poorly reflect the reality of cardiac arrest treatment; while these guidelines may be sound in theory, and even work well during training sessions, they may be too complex for a crisis situation.

Based on these studies, a reevaluation of both guidelines and practice seems to be in order. Even though strictly adhering to CPR guidelines would presumably save lives, it may not be a realistic option. Nevertheless, it is clear that any CPR is better than no CPR, and every effort should be made to get the victim of a cardiac arrest definitive lifesaving treatment as quickly as possible.