AHA: Therapeutic hypothermia decisions might be too subjective

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CHICAGO—With an ICU-centered therapeutic hypothermia (TH) program and no formal screening mechanism for patients in the emergency department, the subjective assessment of prior health status may influence the decision for medical staff to initiate TH for comatose survivors of cardiac arrest, according to a scientific poster presented on Nov. 13 at the American Heart Association (AHA) Scientific Sessions.

Out-of-hospital sudden cardiac arrest (SCA) has an estimated annual incidence of 0.04 to 0.19 percent in industrialized countries (Cochrane Database Syst Rev 2009;4:CD004128), and affects approximately 400,000 individuals causing at least 325,000 deaths in the U.S. annually, the researchers reported. Although SCA risk is associated with structural heart disease and other comorbid conditions, many SCA victims have no history of chronic disease.

Overall, out-of-hospital cardiopulmonary resuscitation for SCA results in 10 to 20 percent survival to hospital admission (Cochrane Database Syst Rev 2009;4:CD004128). Of those patients who reach the hospital, fewer than 20 percent survive to hospital discharge. Similarly, survival rates are poor following in-hospital cardiac arrest with immediate return of spontaneous circulation and initiation of advanced post-resuscitation care (Resuscitation 2009;80(9):981-4).

Heather M. Ross, DNP, from Brandman University in Irvine, Calif., and her colleagues at the Hospital of Saint Raphael in New Haven, Conn., also noted that randomized controlled trials of post-resuscitation TH have led to clinical practice guidelines for post-SCA TH, and the therapy has been incorporated in the overall guidelines for post-resuscitation care for adult SCA survivors.

Ross and colleagues reported that TH was initiated on an ad hoc basis for comatose survivors of cardiac arrest in the Hospital of Saint Raphael, a 511-bed community teaching hospital, in October 2008. In December 2008, an evidence-based pilot protocol was adopted for TH. The screening process and implementation of this protocol was centered in the ICU and driven by attending intensivist staff.

The researchers conducted a retrospective chart review of 16 consecutive months around the pilot protocol implementation to evaluate the provider’s TH implementation rates, compared with published literature from other trial and registry data.

They noted that implementation rates and baseline demographics did not vary according to presence or absence of the pilot protocol. With “no apparent impact of the protocol in terms of TH initiation,” they analyzed data to determine whether baseline characteristics impacted the decision to initiate TH.

In a 16-month period, 15 percent of the patients eligible for the TH protocol  had TH initiated. The only baseline difference in TH and non-TH groups at baseline was the subjective perception of being “healthy” prior to cardiac arrest.

“However subjective assessments did not always reflect the actual presence or absence of comorbid conditions that might influence survival and neurological outcomes,” the study authors wrote.

Therefore, Ross and colleagues concluded that “a defined evidence-based screening tool in both emergency department and ICU settings may eliminate subjective disparities for TH initiation, and improve the use of TH for appropriate patients. “However, they added that further assessment of such a screening tool is warranted to evaluate impacts on TH initiation.

The findings were presented during the fourth annual Resuscitation Science Symposium, which runs concurrent to the AHA conference.