Nancy A. Melville

January 26, 2015

PHOENIX — The use of diastolic blood pressure and end tidal carbon dioxide measures to guide in-hospital cardiopulmonary resuscitation (CPR) is associated with a significant improvement in the chance of survival from cardiac arrest, according to new research.

"Healthcare providers need to monitor how the patient is responding to the resuscitation effort," said lead investigator Robert Sutton, MD, from the University of Pennsylvania School of Medicine and the Children's Hospital of Philadelphia.

In fact, they might "need to change their approach if they are not getting good patient physiology during the CPR that they are providing," he told Medscape Medical News here at the Society of Critical Care Medicine 44th Critical Care Congress.

Most in-hospital cardiac arrests occur in the intensive care unit, where blood pressure and carbon dioxide are already closely monitored. Despite that, CPR efforts are typically made in a uniform manner and are not adjusted to those readings.

When the measures are used, CPR is more closely responsive to the patient's immediate needs, Dr Sutton explained.

"This monitoring is a form a personalized medicine; these monitors are a rough approximation of blood flow during CPR," he said. "And we think better blood flow during CPR equates to better patient outcome."

 
We think better blood flow during CPR equates to better patient outcome.
 

Dr Sutton has been involved in previous animal studies that showed that the titration of resuscitation efforts according to the individual's physiology can save lives.

In this study, his team evaluated 245,300 CPR events reported in the Get With the Guidelines – Resuscitation registry of all in-hospital CPR events from 2000 to 2012.

In an analysis of diastolic blood pressure, 11,259 of 16,301 (69%) CPR events resulted in a return of spontaneous circulation, and in 4212 (26%) events, diastolic blood pressure was used to monitor the quality of CPR.

In an analysis of end tidal carbon dioxide, 30,980 of 47,135 (66%) CPR events resulted in a return of spontaneous circulation, and in 1648 (3.5%) events, end tidal carbon dioxide was used to monitor quality.

Events in which an arterial catheter was not used or an invasive airway was in place at the time of the cardiac arrest were excluded from the study.

The return of spontaneous circulation was better when diastolic blood pressure was used to monitor CPR than when it was not after adjustment for potential confounders such as age, sex, race, year of arrest, first pulseless rhythm, and duration of arrest (odds ratio [OR], 1.23, 95% confidence interval [CI], 1.12 - 1.36; P < .001).

The same was true for end tidal carbon dioxide (OR, 1.25; 95% CI, 1.10 - 1.43; < .001).

The association between a return to spontaneous circulation and end tidal carbon dioxide was stronger when the end tidal carbon dioxide achieved was above 10 mm Hg than when it was not (P < .001).

These findings underscore the value of guidance from diastolic blood pressure and end tidal carbon dioxide measures and in CPR decision-making, Dr Sutton said.

"Clinicians may need to push faster, slower, harder, or less hard," he explained. "But the determining factor should be the individual patient, not what works with most patients."

New Targets

"Monitoring has not been emphasized or made a priority in our existing basic and advanced life support classes, likely because there was little human data showing that such a resuscitation approach would improve outcomes over our standard methods," Dr Sutton said. "This study will hopefully begin to change our focus."

This is "an important study because it adds to the body of literature on CPR quality," said Alexandre Rotta, MD, from University Hospitals Rainbow Babies & Children's Hospital in Cleveland.

"For a few years now we have known that not every CPR is effective and that there is significant operator variability in delivering CPR," he told Medscape Medical News.

"The strength of this study is in the large sample," he added.

Although the study has some important limitations, such as its retrospective nature, it nevertheless should spur much-needed additional research, said Dr Rotta.

"It is difficult, if not impossible, to discern whether patients who achieved a higher diastolic blood pressure and higher end tidal carbon dioxide did so because adjustments were made to the CPR process during resuscitation, or whether these patients simply had higher diastolic blood pressure and end tidal carbon dioxide, which have been known for years to be associated with better outcomes," he explained.

"This question can only be answered by a prospective study," he added. "The current study provides enough intriguing evidence to justify such a trial using these two candidate variables as targets during CPR."

Dr Sutton's work is supported by a National Institutes of Health award, he is a member of the Get With the Guidelines – Resuscitation Pediatrics Task Force, and he has received speakers honoraria from Zoll Medical. Dr Rotta has disclosed no relevant financial relationships.

Society of Critical Care Medicine (SCCM) 44th Critical Care Congress: Abstract 225. Presented January 18, 2015.

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