Abstract & Commentary
Commentary by Jacob Ufberg, MD, Assistant Professor of Emergency Medicine, Residency Program Director, Department of Emergency Medicine, Temple University School of Medicine, Philadelphia, PA. Dr. Ufberg is on the Editorial Board of Emergency Medicine Alert.
Source: Abella BS, et al. Chest compression rates during cardiopulmonary resuscitation are suboptimal: A prospective study during in-hospital cardiac arrest. Circulation 2005; 111:428-434.
Approximately 1-6% of patients with out-of-hospital cardiopulmonary arrest survive to hospital discharge. This figure jumps to slightly more than 17% of in-hospital arrests. The study of cardiac arrest during recent years indicates that the timing and quality of caridiopulmonary resuscitation (CPR) have an effect on the incidence of return of spontaneous circulation (ROSC). Studies have demonstrated increased rates of ROSC among patients with shorter delays to CPR, fewer pauses in chest compressions, CPR prior to defibrillation, and the use of chest compression-only CPR.
This study from three hospitals in the Chicago area measured chest compression rates during in-hospital cardiac arrests to determine compliance with published international CPR guidelines (100 compressions per minute [cpm] are recommended). The authors felt that chest compression rates were a readily quantifiable surrogate marker of the quality of CPR, and that the measurement of compression rates at three hospitals would allow them to determine the general quality of CPR provided at in-hospital arrests. The secondary goal of the study was to compare rates of ROSC among patients who received recommended and less-than-recommended compression rates.
Cases included all arrests among patients older than 17 years occurring in one of the three study hospitals. Arrest was defined by the loss of a palpable pulse and the delivery of chest compressions by hospital staff. Persons certified in basic life support delivered all CPR.
Patients were excluded if the arrest occurred in the operating suite or emergency department (ED), or if the investigator arrived at the arrest before other hospital personnel, such that their assistance was needed with the resuscitation. On arrival at an arrest, observers attempted to record compressions without alerting resuscitation providers to their presence.
Compression rates were recorded using a handheld device developed for the study and validated prior to initiation of the study. ROSC was defined as the return of a detectable pulse and perfusing rhythm was maintained for more than five minutes. Arrest recordings were divided into 30-second segments, and the rates computed for each segment were corrected for any pauses more than four seconds during which pulse checks or defibrillation occurred. Average compression rates were recorded for each arrest, and the frequency of ROSC was calculated for each quartile of average compression rates.
During the study period, 813 minutes of resuscitation were recorded during 97 cardiac arrest events. Patients had a mean age of 73 years, and 51% were female. Arrests occurred in ICU settings (55%), ward beds (32%), or in other areas such as the radiology suites (13%). ROSC as defined for this study occurred in 63% of arrests. Average compression rates were measured at 100 + 10 cpm in only 31% of cases, and were fewer than 80 cpm in 37%. Average resuscitation times were higher in patients not achieving ROSC, suggesting that providers were not biased in their compression rates against patients thought to have little chance of survival.
Mean compression rates were compared among patients who did or did not achieve ROSC. Mean rates for patients with ROSC were 90 + 17 cpm compared with 79 + 18 cpm for patients without ROSC (p = 0.003). When patients were grouped into quartiles by average compression rate, the patients in the highest quartile had a 75% rate of ROSC, while the patients in the lowest quartile had a 42% rate of ROSC (p = 0.008).
The authors conclude that chest compressions frequently are delivered at rates below the recommended rate of 100 cpm. The frequency of low rates was similar in all three study hospitals, suggesting a possible widespread problem. While the study was not designed with the power necessary to detect differences in ROSC rates, these differences were statistically significant in both direct and quartile analysis. The authors acknowledge the study’s limitations: 1) possible bias against patients thought to have little chance of survival (i.e., "slow code"), 2) CPR quality goes beyond chest compression rate, 3) human error was possible in the counting of compressions, and 3) data from these three hospitals may not be applicable to hospitals everywhere.
Commentary
The applicability of this study suffers from several limitations. First and foremost, one cannot confuse ROSC, survival to hospital discharge, and good (or fair) neurologic function. Many studies of cardiac arrest use ROSC or survival to hospital admission as an endpoint although few of these patients will ever return home. I would be more interested in the study of compression rates as they relate to survival to hospital discharge; however, in the authors’ defense, this was not a primary goal of the study.
Second, the authors admit that compression rate is only one part of the big picture of the quality of CPR. However, compression rate was used as a surrogate due to its measurability in the chaotic environment of an in-hospital arrest. Third, it is hard to compare ROSC rates when the baseline data of severity of illness are not recorded. It is possible that a far greater number of non-survivors were intensive care unit patients with severe co-morbid illnesses.
Despite these limitations, the major point of the study remains important. Compression rates routinely are suboptimal. We need to find a way to deliver an adequate compression rate during arrests. All CPR is not equal; we need methods that use monitoring and measurement and real-time and post-arrest feedback or debriefing to ensure CPR quality for our most critical patients.
This study from three hospitals in the Chicago area measured chest compression rates during in-hospital cardiac arrests to determine compliance with published international CPR guidelines (100 compressions per minute are recommended).
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