Caring for Patients Treated With Therapeutic Hypothermia

Therapeutic hypothermia involves purposely lowering the core body temperature to 32°C to 34°C for 12 to 24 hours.^3,4  The aim is to reduce metabolic rate and oxygen demand of the body to improve survival and neurological outcomes. Therapeutic hypothermia was formally introduced in the 1950s in both neurological and cardiac surgical cases. Core temperature was lowered to less than 28°C, temperatures that would be considered severe hypothermia today.

The more recent use of therapeutic hypothermia after cardiac arrest to improve neurological recovery was instituted globally after publication of 2 landmark studies^2,3  in 2002. Bernard et al²  and the Hypothermia After Cardiac Arrest Study Group³  corroborated positive outcomes in patients with ventricular fibrillation. In both studies, the percentage of patients treated with therapeutic hypothermia who could be discharged from the hospital to home with good recovery or to a rehabilitation facility with modest disability was higher than the percentage in the nontreatment group. In the study by Bernard et al, 49% of the 43 patients treated with hypothermia (target temperature, 33°C) had good neurological function at discharge compared with 26% of the 34 patients in the normothermia group (core temperature, 37°C). In the study by the Hypothermia After Cardiac Arrest Group, favorable neurological outcomes occurred in 55% of the 136 patients in the hypothermia group (target temperature, 33°C) but in only 39% of the 137 patients in the normothermia group (core temperature, 37°C). Both studies had limitations: exclusion criteria that eliminated 92% of patients assessed for eligibility; statistically nonsignificant physiological complications such as pneumonia, bleeding, and sepsis; and knowledge among patients of the treatment received. Although the focus of the studies was therapeutic hypothermia in patients with shockable rhythms, the benefit of therapeutic hypothermia on nonshockable rhythms and conditions was not ruled out.⁴  The positive outcome ratios of Bernard et al²  and the Hypothermia After Cardiac Arrest Study Group³  were not possible before the advent of hypothermia as a treatment option.

After publication of these 2 landmark studies and the subsequent endorsements of therapeutic hypothermia by the International Liaison Committee on Resuscitation and the American Heart Association, institutions worldwide began to adopt the therapy. The effectiveness of therapeutic hypothermia gained further credence when the Advanced Cardiac Life Support update added consideration of the therapy to the algorithm for treatment after cardiac arrest.^5,6  A vast array of publications on therapeutic hypothermia address the efficacy of the treatment (Table 1).

In a prospective study published in 2006, Oddo et al⁷  evaluated the use of therapeutic hypothermia outside the original indication of patients with cardiac arrest due to ventricular fibrillation. The results indicated a strong correlation between the length of time from collapse to return of spontaneous circulation (< 30 minutes with resuscitation by emergency personnel, P = .09) and the probability of survival and a good neurological outcome. Oddo et al defined a good neurological outcome by using the 5-point Pittsburgh Cerebral Performance Category Scale (from 1 = good recovery to 5 = death). In 2012, Storm et al¹⁶  published the results of an observational study to compare outcomes for patients who received therapeutic hypothermia in both shockable and non-shockable rhythms. They concluded that no significant improvement in neurological outcome occurred when the cardiac arrest was not due to ventricular fibrillation.

In a more recent study published in 2013, Nielsen et al¹⁸  compared the previously established target temperature of 33°C with a target temperature of 36°C. In this large, multicenter, randomized international trial, patients in the 33°C group did not differ significantly from patients in the 36°C group in overall mortality and neurological outcome at 180 days. The results led to a debate among experts in therapeutic hypothermia for several reasons, including the wide range of times for return of spontaneous circulation; lack of clearly defined neurological outcomes; large deviation in temperature ranges in both groups of patients; neurological examination at 72 hours, a time too early for drug clearance in patients in the 33°C group; and lack of measurement of hemodynamic parameters, leading to further questions about the benefit of temperature management.¹  The study¹⁸  differed from other studies by actively controlling the patients’ body temperature during the intervention period and intended to prevent fever during the first 3 days of treatment.

In 2007, Bader et al⁸  published a case report on use of hypothermia after resuscitation. They reported that the rapid coordination of care via use of a multidisciplinary protocol improved the patient’s outcome. Bader et al credited ongoing communication among the interprofessional team as a key factor to ensure timely modifications in the treatment plan. Likewise, in 2009, Kupchik¹⁰  detailed the benefits of a collaborative team approach in successfully developing and implementing a protocol for therapeutic hypothermia at a medical center in Seattle, Washington.

Recognizing the challenges associated with therapeutic hypothermia, the Joint Commission issued a call for participation in performance measurement initiatives, specifically use of therapeutic hypothermia in patients after cardiac arrest.¹³  One article published in response to the request detailed the initiation of therapeutic hypothermia at the University of Alabama, Birmingham, Alabama. Spearheaded solely by the emergency medicine attending physicians and with no protocols for care beyond the emergency department, the therapeutic hypothermia program was stopped after just 1 week. Concerns related to the exclusion of key stakeholders led to an internal decision to stop and restructure the program.

Program revisions began with formation of an interprofessional team representing physicians and nurses of relevant specialties, pharmacists, and information services. One key intervention was to ensure that a physician expert in therapeutic hypothermia was always available as a resource to facilitate consistent care practices. This step led to development of a formal physician consulting service on therapeutic hypothermia and a rapid multidisciplinary response team. During a 21-month period, 36% of patients (n = 93) treated with therapeutic hypothermia survived to discharge from the hospital. Of those, 73% had good neurological outcome according to scores less than 3 on a modified Rankin Scale.^9,13 

Interprofessional collaboration was also a factor addressed by Mooney et al.¹¹  These authors challenged the current practice that after cardiac arrest, various treatments, including therapeutic hypothermia, should be offered in all hospitals. They advised developing cardiac resuscitation centers of excellence, which would offer more intensive, interprofessional services beyond the initial Advanced Cardiac Life Support efforts after resuscitation. Mooney et al implemented a process that facilitated early cooling at the local level with immediate transport to a regional center to initiate complex therapies. Their research illustrates use of established cardiac care networks with refined patient transfer mechanisms as a model to enhance access to and outcomes of therapeutic hypothermia.

In summary, published results support the notion that timely resuscitation and implementation of a therapeutic hypothermia protocol (< 30–60 minutes from start of resuscitation to return of spontaneous circulation) in patients after cardiac arrest are tied to improved neurological outcomes and return to home.^12,14,17,19  Further, an interprofessional team involving providers, nurses, and ancillary staff is essential for success.

Therapeutic hypothermia had been used within the Lehigh Valley Health Network, Allentown, Pennsylvania, as a treatment option for neurological protection in patients with large hemispheric stroke since 2002. Initially, oversight for this treatment was the responsibility of neuroscience physicians and clinical nurse specialists. In 2005, prompted by new information, therapeutic hypothermia was initiated to preserve neurological function in patients who had had cardiac arrest. This expanded use of therapeutic hypothermia was the impetus to develop a formal clinical practice guideline and assemble an interprofessional team of experts to oversee implementation and ensure ongoing evaluation.

The initial purpose of the interprofessional team was to develop an evidence-based clinical practice guideline and associated processes to support implementation of the therapy. The committee consisted of representatives from providers responsible for the care of patients treated with therapeutic hypothermia. Specific members included physicians from emergency medicine, cardiology, and neurology; critical care intensivists; nurse managers, educators, clinical specialists, and direct care nurses; pharmacists; respiratory therapists; and prehospital personnel.

The original guideline addressed general care practices and treatment interventions specific to the stages of induction, maintenance, and rewarming. Over time, the guideline has been revised to include enhancements within each stage. The goal remains as it was originally conceived: to provide evidence-based recommendations to be used by emergency medicine physicians, neurologists, cardiologists, intensivists, and nurses who provide care for patients who have had an anoxic injury and who meet inclusion criteria for therapeutic hypothermia. Figures 1 to 3 detail the most recent clinical practice guideline for the 3 phases of therapeutic hypothermia: induction, maintenance, and rewarming.

Over time, the purpose of the therapeutic hypothermia committee has evolved from development and refinement of a guideline to identification of care quality issues requiring further action. The committee also discusses new evidence. Any new information can trigger revisions to the current clinical practice guideline and further education of staff members. Each member of the inter-professional team is charged with disseminating committee outcomes to colleagues in his or her designated specialty. Other committee actions and practice improvements include ongoing review of criteria for inclusion and exclusion; medication management; ventilation protocols; optimization of management of hemodynamic parameters; and ethical dilemmas associated with patients who have had cardiac arrest.

The monthly, 90-minute meeting begins with clinical nursing leaders’ presenting therapeutic hypothermia cases to the interdisciplinary team. The presentation includes a brief patient history, clinical course, and any variances from the clinical practice guideline. Discussion by team members further identifies any performance, quality, or interdepartmental problem that may require attention. Collaboration between disciplines and interdepartmental relations has been enhanced by this clinical case review. An unexpected benefit of these reviews has been identification of ongoing educational needs of clinical team members and opportunities to reinforce adherence to the practice guideline.

The number of stakeholders in the guidelines for therapeutic hypothermia has increased from 3 clinical champions (2 neuroscience clinical specialists and a neurologist) to a highly effective interprofessional care delivery team dedicated to optimizing therapeutic hypothermia. From the onset, members of the team were influenced by their commitment to improve the care of patients receiving this therapy. Physicians’ knowledge and acceptance of and willingness to actively support the guidelines were critical to incorporate therapeutic hypothermia as an option for clinical practice. Initial strategies to gain physicians as stakeholders included formal presentations of current evidence on therapeutic hypothermia and review of the institution’s temperature management guideline at department-specific physicians’ grand rounds. Presenters included the 2 neuroscience clinical nurse specialists and a physician intensivist. During this period, as physicians became acquainted with the therapy, nurses were early adapters and champions. They became patient advocates for therapeutic hypothermia, often raising the option with physician colleagues.

As more patients received therapeutic hypothermia, the need for medical care for the patients beyond that provided by the originating neurologist was necessary. For example, as the therapy was used with patients with more complex conditions, multiorgan system optimization required strategic recruitment of defined medical specialists as stakeholders. Each physician chief (cardiology, neurology, and critical care medicine) was requested to designate a minimum of 1 staff member to become the physician expert on therapeutic hypothermia in the member’s specialty. Other professional stakeholders whose involvement was garnered via membership on the committee included pharmacists, respiratory therapists, pastoral care staff, palliative care staff, nurse coordinators of the stroke and acute coronary syndrome services, and the cardiology nurse administrator.

Initially, because of the neuroprotective benefits of therapeutic hypothermia, patients who received the therapy were treated in the neuroscience intensive care unit (ICU). As our understanding of the care needed after resuscitation evolved, we realized that patients who receive therapeutic hypothermia often require advanced cardiac interventions and support. Thus, the decision was made for these patients to be managed in a cardiac-focused ICU. The continually updated clinical practice guidelines have offered bedside staff, regardless of the setting, the information to ensure best practice.

One of the critical components the therapeutic hypothermia committee devised and implemented is rapid deployment of resources, termed ICE Alert, to extend resuscitation after cardiac arrest. Specially trained staff familiar with therapeutic hypothermia respond to the alert and actively assist in accelerated triage of patients to the ICU, with rapid initiation of cooling. The ICE Alert was modeled on the existing efficient flow used to treat patients with acute myocardial infarction. An ICE Alert is initiated via the hospital’s paging system for both emergency department admissions and in-house cardiac arrests. An ICU nurse responds immediately with 2 L of iced physiological saline and the external cooling pads while other ICU staff members prepare the patient room for the patient’s arrival. Figure 4 shows the ICE Alert algorithm.

A vital component for successful therapeutic hypothermia was to identify, plan, and ensure delivery of education and training, including both prehospital and acute care interprofessional stakeholders. Initial teaching strategies included didactic offerings with case scenarios to stimulate critical thinking and simulations of technical and psychomotor skills. Targeted audiences were prehospital personnel; emergency department, ICU, and invasive cardiology nurses and technical staff; respiratory therapists; medical residents and cardiology fellows; and cardiologists, neurologists, and critical care intensivists. Education involved regularly occurring forums: orientation; grand rounds; “lunch and learn”; unit staff meetings; and formal continuing education programs, such as the annual nursing research day, medical specialty symposiums, and an electronic learning curriculum. In addition, 2 half-day symposia with nationally renowned experts in therapeutic hypothermia were offered.

Because ICU nurses are the team members who provide round-the-clock care for patients who receive therapeutic hypothermia, clinical nurse educators developed a multifaceted educational plan. After unit orientation and assessment of staff readiness, ICU nurses undergo 3 hours of didactic offerings, including pathophysiology of sudden cardiac death and needs after resuscitation, an overview of techniques of therapeutic hypothermia, and management of complications. Table 2 outlines objectives, content, time frame, and methods of the educational plan. Emphasis is placed on prevention of arrhythmias, potential issues with altered vital signs, skin problems, fluid and electrolyte disturbances, hyperglycemia, clotting issues, infection, seizures, shivering, and the decrease in clearance of medications.

The next step is coassignment with a preceptor to a patient treated with therapeutic hypothermia as long as necessary, until competency is demonstrated. In order to ensure ongoing proficiency, annual demonstration of knowledge of therapeutic hypothermia is required. Case-based reviews have continued to provide learning opportunities that have further improved both collaboration among the clinical team and the delivery of care.

Resources available to nurses caring for a patient treated with therapeutic hypothermia include 24-hour availability of clinical experts, a hard-copy resource manual, the clinical practice guideline, manufacturers’ equipment manuals, and current evidence-based literature. These published articles are summarized within Table 1 as an evidence table. Nursing staff are also encouraged to seek out presentations on therapeutic hypothermia at local, regional, and national conferences and to share learning with colleagues after the presentations.

Although acceptance of therapeutic hypothermia was developing, formal case review enhanced use of the therapy. Real-time case review by the interprofessional care team occurs daily at the bedside of patients treated with therapeutic hypothermia. Each patient’s progress over the preceding 24 hours is assessed, and decisions for the prospective plan of care are made.

In addition to these interprofessional reviews, the unit educator or manager reviews each patient receiving therapeutic hypothermia with the primary nurse throughout the shift to foster critical thinking that translates the scientific evidence to the patient’s specific needs. At the monthly meeting of the therapeutic hypothermia committee, case reviews are offered by using a standard communication template (situation, background, assessment, and recommendation). Care processes and outcomes are reviewed, and opportunities for improvement are identified.

From the onset, the therapeutic hypothermia committee recognized the necessity to use data to improve the processes and outcomes of the therapy. After beginning with process metrics and rudimentary patient scales, evaluation and analysis have progressed to participation in an international therapeutic hypothermia data registry known as the International Cardiac Arrest Registry. Originally, the registry did not include data from North America. When it was expanded to North America, a goal was to develop cardiac end points that would further define use of therapeutic hypothermia after cardiac arrest. Lehigh Valley Health Network is 1 of 6 centers submitting data to develop these end points. Case abstraction allows comparison of internal data with registry data aggregates to enhance therapeutic hypothermia practices. Table 3 compares our recent data with those of the international registry.

At this time, we have used therapeutic hypothermia for more than 200 adult patients during an 8-year period. Our experience matches published outcomes for patients with ventricular tachycardia and fibrillation treated with therapeutic hypothermia: approximately 50% patient survival with minimal disability. Use of therapeutic hypothermia after resuscitation for other causes, such as pulseless electrical activity, asystole, and secondary cardiac arrests due to such conditions as drug overdose and asphyxiation, has had limited success.

A decade ago, families of patients who had had a cardiac arrest were told to “watch and wait” regarding their loved ones’ survival; the common belief was that recovery, if it were to occur, takes time and interventions were aimed at basic supportive care. Therapeutic hypothermia has redefined care after resuscitation and provides an aggressive intervention that may mitigate postresuscitation syndrome.

Use of therapeutic hypothermia is still in its infancy. For continued development of the therapy, clinicians must continue to learn and enhance the evidence with each patient. First and foremost, use must be in accordance with established evidence-based protocols. Our experience has shown that, beyond a protocol, the critical elements of success we detailed have enhanced translation of the evidence on therapeutic hypothermia into practice.

We acknowledge the editorial assistance of Kim S. Hitchings, rn, msn, nea-bc, manager, Center for Professional Excellence, Lehigh Valley Health Network.