THERAPEUTIC HYPOTHERMIA AND TEMPERATURE MANAGEMENT Volume 1, Number 1, 2011 ª Mary Ann Liebert, Inc. DOI: 10.1089/ther.2010.0004
Original Articles
Use of Therapeutic Hypothermia in Postcardiac Arrest Patients by Emergency Departments Dina Seif1 and Sean O. Henderson1,2
Since 2003, resuscitation guidelines have recommended the use of induced hypothermia as a therapy for patients who achieve return of spontaneous circulation after cardiac arrest from ventricular fibrillation. The aim of this study was to survey emergency physicians across the United States on their use of therapeutic hypothermia (TH) after cardiac arrest. An 18-question survey was e-mailed to a sample of emergency physicians. Fifty-eight respondents completed the survey. Most (71%) were associated with an emergency medicine residency training program. Annual census ranged from 12,000 to >170,000 visits. TH is used by the majority (69%) of respondents, 79% of which report the presence of a formal institutional protocol. The majority of respondents use TH in arrest rhythms including but not limited to ventricular fibrillation, and 21% begin the process in the prehospital setting. To induce hypothermia, a majority of respondents use commercial cooling products. The average time to target temperature was 95 minutes. The majority of respondents report a goal temperature between 328C and 348C. A shivering protocol is used by 76% of respondents, and as a first line medication, 46% use benzodiazepines. For those who do not use TH or do not have a protocol in place, the reasons cited include ‘‘too expensive,’’ ‘‘too difficult to implement,’’ and ‘‘not enough science to warrant it.’’ In this sample of practicing emergency physicians, TH after cardiac arrest is not being used as described in the original literature. Although awareness and implementation of TH have increased, there appears to be a wide variation in the application of this therapy.
committees and Task Forces of the American Heart Association, 2005). Large, multicenter, randomized, controlled trials will be necessary to investigate the utility of therapeutic hypothermia (TH) in postarrest resuscitation. The first step to this process is analyzing experiences, opinions, and current applications of TH in emergency departments across the United States. A survey of practicing emergency physicians was created to gain insight into the types of patients selected, what devices and techniques are being employed, and how hospital-wide protocols are being developed. Only by understanding the barriers to implementing this therapy we can begin to develop and adjust critical pathway protocols for widespread use.
Introduction
S
urvival and favorable neurologic recovery are uncommon after cardiac arrest, likely because of mechanisms of cerebral injury caused by brain anoxia and the resulting inflammatory cascades that follow. In 2002, two separate randomized controlled studies demonstrated that induced hypothermia after cardiac arrest from ventricular fibrillation (VF) improved neurologic outcomes (Bernard et al., 2002; Hypothermia after Cardiac Arrest Study Group, 2002). Prior to these findings, standard postcardiac resuscitation was directed at preventing dysrhythmias and providing circulatory support without any specific therapy to limit neurologic damage. The current guidelines from the Advanced Life Support Task Force of the International Liaison Committee on Resuscitation (ILCOR) recommend that unconscious adult patients with spontaneous circulation after out-of-hospital cardiac arrest should be cooled to 328C–348C for 12–24 hours when the initial rhythm is VF (ECC Committee and Sub-
Methods The study protocol was approved by the University of Southern California Institutional Review Board.
Departments of 1Emergency Medicine and 2Preventive Medicine, Keck School of Medicine of the University of Southern California, Los Angeles, California.
23
24
SEIF AND HENDERSON Table 1. Demographic Data
Study design This is a cross-sectional descriptive study of the use of TH after return of spontaneous circulation (ROSC) postcardiac arrest in emergency departments across the United States. These findings are based on survey responses collected between January 2009 and April 2009. Enrollment The authors recruited a diverse sample of emergency physicians from different clinical practice settings across the United States, which included alumni of a large inner-city residency program and members of the SAEM Research Directors Interest Group. E-mail invitations were sent to 100 emergency physicians. Survey An 18-question, Internet-based survey was created consisting of Likert scales, categorical responses, single answers, and multiple choice. The survey had five separate categories: physician demographic data, emergency department characteristics, use of TH including patient selection and prehospital care, methods for TH including shivering protocol, and opinions on TH. Results The response rate was 58%. Two responses from emergency medical systems representatives were excluded as they were not specific to any particular emergency department. A third response from a non-emergency physician was excluded.
No. (%) of responses ED characteristics Private Public University Public university Kaiser Veterans administration Private public ED censusa 25,000 or less 25,001–50,000 50,001–75,000 75,001–100,000 100,001–125,000 More than 125,000 Emergency medicine residency Yes No
23 12 12 4 2 1 1
(41.8) (21.8) (21.8) (7.3) (3.6) (1.8) (1.8)
2 14 23 10 3 1
(3.8) (26.4) (43.4) (18.9) (5.6) (1.9)
39 (70.9) 16 (29.1)
a Emergency department (ED) census was not provided by two institutions.
reported protocols being developed by multidisciplinary teams involving various departments and nursing (Table 3). Twenty-one percent initiate TH in the prehospital setting. Indications Seventy-six percent of respondents use TH in all cardiac arrest patients who achieve ROSC, including, but not limited to, VF. Ten percent use it in patients with ROSC only after VF.
Demographics Survey participants represented 18 states across the country. Respondents represented a good distribution of practice environments including private, public, and university hospitals (Fig. 1). The majority of respondents were associated with an emergency medicine residency training program. Annual census ranged from 12,000 to 170,000, with an average of 66,000. Table 1 summarizes the demographics of respondents. Thirty-one percent of respondents to the survey do not use TH after cardiac arrest. Reasons for nonuse are listed in Table 2. TH is used by 69% of respondents, with 79% of these reporting a formal TH protocol at their institution. Over half of respondents reported that their TH protocol was always initiated in the emergency department. Forty-two percent
Cooling methods A wide variety of cooling techniques exist. Most respondents use a commercial product (Fig. 2) to achieve hypothermia. The average goal time to reach target temperature is 115 minutes, with a range of 20–240 minutes. The majority use a target temperature between 328F and 348F. Only one respondent reported a target temperature outside the ILCOR recommended range at 288C.
Table 2. Use of Therapeutic Hypothermia and Reasons for Nonuse No. (%)
60%
Private
40%
Public
92%
University
75%
EM residency No residency
FIG. 1.
8% 25%
82% 38%
18% 63%
Distribution of therapeutic hypothermia use.
Yes No Protocol development in process Not enough scientific evidence Have not been able to agree on a protocol Have not thought about it Too complicated/difficult Not part of ACLS Resistance from other departments Not used locally Too expensive Respondents were allowed multiple responses. ACLS, actual cardiac life support.
38 17 5 5 5 5 4 3 2 1 1
(69.1) (30.9) (29.4) (29.4) (29.4) (29.4) (23.5) (17.6) (11.7) (5.9) (5.9)
THERAPEUTIC HYPOTHERMIA IN THE ED
25
Table 3. Therapeutic Hypothermia Characteristics
Percentage of respondents 0%
No. (%) of responses 30 (78.9) 5 (13.2) 20 (52.6) 14 (36.8) 1 (2.6)
Participants were asked how they felt about the following statement: ‘‘Therapeutic hypothermia improves survival and promotes a better neurologic outcome in the cardiac arrest patient.’’ Forty-seven of the participants strongly agreed with
Cooling methods.
80%
71%
45% 13% 32% 3%
None
3%
Discussion
70%
3%
Propofol Combination
(10.5) (55.3) (15.8) (2.6)
Opinions
50% 60% 55%
Paralytic
4 21 6 1
Seventy-six percent of respondents have a protocol to address and prevent shivering. The majority use benzodiazepines and/or paralytics, with benzodiazepines being the most popular as a first-line medication (Fig. 3). One respondent reported using propofol as a first-line medication to prevent shivering.
40%
71%
Benzodiazepene Opiate
FIG. 3.
Shivering protocols
FIG. 2.
Propofol
(40) (34.3) (11.4) (5.7) (2.9)
a Thirty-five of 38 respondents who use TH answered whether they had a protocol and how often it was initiated in the ED. Respondents were allowed multiple responses regarding protocol development. TH, therapeutic hypothermia; EM, emergency medicine.
30%
Opiates Paralytics
14 12 4 2 1
8 (21.1) 28 (73.7)
20%
Benzodiazepenes
First Line Medication
Official hypothermia protocola Yes No How often TH is initiated in the EDa Always Sometimes Never TH protocol created by Multidepartments EM Pulmonary critical care Neurology Cardiology Frequency of use Weekly Monthly Once every 3 months Once a year Prehospital TH Yes No
10%
3%
Use of paralytics and sedatives to prevent shivering.
this statement, 35% somewhat agreed, 7% were neutral, and 2% somewhat disagreed.
Implementation of TH in emergency departments has been slow despite treatment recommendations from ILCOR since 2003. A study surveying emergency physicians, cardiologists, and critical care physicians in 2005 found that only 13% had ever used TH after cardiac arrest (Abella et al., 2005). Reasons cited included the perception that TH is difficult to accomplish, requires large amounts of resources, and carries dangerous side effects. The use of TH in arrest rhythms other than VF, such as pulseless electrical activity (PEA) or asystole, has not been well studied and there have been no large studies examining the use of TH after primary respiratory failure, trauma, drowning, hanging, in-hospital arrests, or pediatric arrests. The current ILCOR recommendations are based on findings from studies of cardiac arrest due to VF or nonperfusing VT (Bernard et al., 2002; Hypothermia after Cardiac Arrest Study Group, 2002). Our survey found that many emergency physicians appear to be using TH regardless of the arrest rhythm. Non-VF dysrhythmias are the most common in cardiac arrest, but they have the poorest outcomes (Stratton and Niemann, 1998). It does not seem unreasonable to apply TH to survivors of asystolic or PEA arrest because the mechanisms by which hypothermia is postulated to improve neurologic outcomes after anoxic brain injury should not differ based on the cause of the arrest. To date, this concept has no support in the literature (Oddo et al., 2006; Don et al., 2009). One study found that asystolic and PEA arrests had longer times to ROSC compared with VF/VT, and poor outcomes in this setting were not altered by TH (Oddo et al., 2006). In initial human studies, TH appeared to improve survival even when delayed hours after resuscitation (Bernard et al., 2002; Hypothermia after Cardiac Arrest Study Group, 2002). Animal studies, however, have found that a delay in hypothermia after ROSC as short as 15 minutes negates the benefit of TH (Kuboyama et al., 1993). There are no data from randomized, controlled studies that addresses whether outcomes in humans could be improved by decreasing time between ROSC and hypothermic target temperature. However, time to achieve hypothermia was an independent predictor of good neurologic outcome in one study, with every hour delay leading to a 31% decrease in likelihood for favorable neurologic recovery (Wolff et al., 2009). A recent study evaluating the use of a conductive-immersion surface cooling device
26 achieved rapid cooling times averaging 37 minutes (Howes et al., 2010) and reported survival and neurologic function that were superior to those from randomized, controlled trials with cooling times averaging 120–480 minutes. The physicians in our survey reported an average goal time to reach target temperature within 2 hours from ROSC; however, the range was quite large (20–240 minutes). Only half of the respondents in this survey start the hypothermia process in the emergency department, which highlights the importance of cooperation with intensive care units and critical care physicians in the management of postarrest resuscitation. More importantly, it raises the question of whether survival and neurologic outcome can be improved if hypothermia was initiated in the emergency department or perhaps even in the prehospital setting. The protocol described by an Australian group initiated cooling measures during transport to the emergency department (Don et al., 2009), but our survey found that most emergency medical systems had not yet incorporated TH into the prehospital setting. Rapid infusion of 48C crystalloid has been shown to be relatively easy, safe, and effective in achieving mild hypothermia after hospital arrival (Kim et al., 2005, 2007; Kamarainen et al., 2008). There may be additional benefit to initiating hypothermia prior to emergency department (ED) arrival, even as early as the arrest period prior to ROSC. Animal data suggest that intra-arrest hypothermia may improve the success of defibrillation (Boddicker et al., 2005) and that benefits of TH are only seen when initiated immediately after ROSC (Kuboyama et al., 1992, 1993). Most respondents to our survey use a target range of 328C– 348C as recommended by ILCOR and the majority have specific shivering protocols to sedate or paralyze patients to decrease energy and oxygen demands. Surprisingly, several institutions describe the use of paralytics as first-line medications without associated sedation. It is known that hypothermia reduces the clearance of medications that are metabolized by the cytochrome P450 system (Tortorici et al., 2007), such as those used in many shivering protocols. However, data are lacking in terms of efficacy and safety of specific medications in this setting. The optimal cooling techniques for induction, maintenance, and reversal of TH have yet to be described and validated. Commercial products are increasingly used to achieve hypothermia in the emergency department. Products used by respondents to this study ranged from invasive central catheters to simple cooling blankets, and a large number of physicians reported using commercial products in combination with traditional cooling methods such as ice bags and cooled saline. Although advances in technology and availability of new products have made the process of cooling easier to induce and maintain, there are limited data comparing the use of specific products. The cost of invasive devices is even higher when the additional expense of physician and nursing time are factored in. Barriers In evaluating the barriers to implementation of TH, we can apply a framework originally created by Cabana et al. (1999) and adapted to the subject of TH by Brooks and Morrison (2008). Using seven general categories, Brooks identified specific obstacles to changing knowledge, attitudes, and
SEIF AND HENDERSON behavior in the care of postcardiac arrest patients. Applying this framework to our results, we found several major themes in the challenges to TH implementation among respondents to our survey. There appears to be a lack of awareness and familiarity with TH despite recommendations from ILCOR and AHA. Five of 17 respondents answered ‘‘have not thought about it’’ as a reason for they do not use TH, demonstrating a disconnect from advisory statements and guidelines by international and national health agencies. Respondents who reported TH ‘‘is not used locally’’ are entrenched in the inertia of previous practice. Lack of agreement manifests as skepticism of research findings and concerns about adverse effects. Despite two randomized, controlled trials, the number of patients studied is relatively small, long-term data are lacking, and the use of TH in arrest rhythms other than VF has not been well studied. Guideline-related barriers result from a lack of concrete protocols. Unlike the well-established, standardized, and highly protocolized algorithms for basic and advanced life support (BLS) and actual cardiac life support (ACLS), TH is not a core component of resuscitation curricula. Disagreement on protocols between departments, an example of interprofessional barriers, was a strong factor in this study for many respondents who do not use TH. Traditional postresuscitative care requires large amounts of physician and nursing time. The addition of a complex therapy requiring close monitoring and management poses an additional lack of self-efficacy barrier to those who perceive TH to be too complicated, time consuming, and difficult to accomplish. Finally, perhaps most critical is the lack of outcome expectancy in which there is a sense of futility for improved outcomes in comatose patients after cardiac arrest. Limitations Despite a relatively high response rate to this survey, the sample size is small and our findings may not be generalizable to all emergency departments in the United States. Respondents represented public, private, and university hospital settings; however, the majority were associated with emergency medicine teaching programs with academic emphases, which may skew our results. Regional differences may be reflected in our results because a large proportion of respondents practice in California. Additionally, the results of this study are subject to responder bias because emergency physicians who currently initiate hypothermia after cardiac arrest or have an interest in doing so are more likely to have responded to our survey. Conclusion It appears that emergency physicians are gradually incorporating TH into their clinical practice when resuscitating patients who achieve ROSC after cardiac arrest. However, TH is not being used as described in the original literature, and it is not being used uniformly across emergency departments. Therapeutic targets differ in terms of target temperature and cooling times, and medications to prevent shivering vary tremendously. Such disparity underscores the need for large, multicenter validation studies to establish the optimal methods for inducing and maintaining hypothermia. Until such guidelines exist, it is the responsibility of departments and
THERAPEUTIC HYPOTHERMIA IN THE ED hospitals to create protocols that will address barriers, facilitate implementation, and encourage a multidisciplinary approach to the postcardiac arrest patient and the use of TH. Disclosure Statement The authors declare that no competing financial interests exist. References Abella BS, Rhee JW, Huang KN, VandenHoek TL, Becker LB. Induced hypothermia is underused after resuscitation from cardiac arrest: a current practice survey. Resuscitation 2005;64: 181–186. Bernard SA, Gray TW, Buist MD, Jones BM, Silvester W, Gutteridge G, Smith K. Treatment of comatose survivors of outof-hospital cardiac arrest with induced hypothermia. N Engl J Med 2002;346:557–563. Boddicker KA, Zhang Y, Zimmerman MB, Zimmerman MB, Davies LR, Kerber RE. Hypothermia improves defibrillation success and resuscitation outcomes from ventricular fibrillation. Circulation 2005;111:3195–3021. Brooks SC, Morrison LJ. Implementations of therapeutic hypothermia guidelines for post-cardiac arrest syndrome at a glacial pace: seeking guidance from the knowledge translation literature. Resuscitation 2008;77:286–292. Cabana MD, Rand CS, Powe NR, Wu AW, Wilson MH, Abboud PA, Rubin HR. Why don’t physicians follow clinical practice guidelines? A framework for improvement. J Am Med Assoc 1999;282:1458–1465. Don CW, Creighton W, Longstreth WT, Maynard C, Olsufka M, Nichol G, Ray T, Kupchik N, Deem S, Copass MK, Cobb LA, Kim F. Active surface cooling protocol to induce mild therapeutic hypothermia after out-of-hospital cardiac arrest: a retrospective before-and-after comparison in a single hospital. Crit Care Med 2009;37:3062–3069. ECC Committee, Subcommittees and Task Forces of the American Heart Association. American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation 2005;112:IV1–IV211. Howes D, Ohley W, Dorian P, Klock C, Freedman R, Schock R, Krizanac D, Holzer M. Rapid induction of therapeutic hypothermia using convective-immersion surface cooling: safety, efficacy, and outcomes. Resuscitaton 2010;81:388–392. Hypothermia after Cardiac Arrest Study Group. Mild therapeutic hypothermia to improve the neurologic outcome after cardiac arrest. N Engl J Med 2002;346:549–556.
27 Kamarainen A, Virkkunen I, Tenhunen J, Yli-Hankala A, Silfvast T. Prehospital induction of therapeutic hypothermia during CPR: a pilot study. Resuscitation 2008;76:360–363. Kim F, Olsufka M, Carlbom D, Deem S, Longstreth WT, Hanrahan M, Maynard C, Copass MK, Cobb LA. Pilot study of rapid infusion of 2 L of 48C normal saline for induction of mild hypothermia in hospitalized, comatose survivors of outof-hospital cardiac arrest. Circulation 2005;112:715–719. Kim F, Olsufka M, Longstreth WT, Maynard C, Carlbom D, Deem S, Kudenchuk P, Copass MK, Cobb LA. Pilot randomized clinical trial of prehospital induction of mild hypothermia in out-of-hospital cardiac arrest patients with a rapid infusion of 48C normal saline. Circulation 2007;115:3064–3070. Kuboyama K, Safar P, Radovsky A, Tisherman SA. Immediate but not delayed mild cerebral hypothermia improves outcome after cardiac arrest in dogs. Crit Care Med 1992;20 (abstract). Kuboyama K, Safar P, Radovsky A, Tisherman SA, Stezoski SW, Alexander H. Delay in cooling negates the beneficial effect of mild resuscitative cerebral hypothermia after cardiac arrest in dogs: a prospective, randomized study. Crit Care Med 1993; 21:1348–1358. Oddo M, Schaller MD, Feihl F, Ribordy V, Liaudet L. From evidence to clinical practice: effective implementation of therapeutic hypothermia to improve patient outcome after cardiac arrest. Crit Care Med 2006;34:1865–1873. Stratton SJ, Niemann JT. Outcome from out-of-hospital cardiac arrest caused by nonventricular arrhythmias: contribution of successful resuscitation to overall survivorship supports the current practice of initiating out-of-hospital ACLS. Ann Emerg Med 1998;32:448–453. Tortorici MA, Kochanek PM, Poloyac SM. Effects of hypothermia on drug disposition, metabolism, and response: a focus of hypothermia-mediated alterations on the cytochrome P450 enzyme system. Crit Care Med 2007;35:2196–2204. Wolff B, Machill K, Schumacher D, Schulzki I, Werner D. Early achievement of mild therapeutic hypothermia and the neurologic outcome after cardiac arrest. Int J Cardiol 2009;133: 223–228.
Address correspondence to: Sean O. Henderson, M.D. Department of Emergency Medicine LAC þ USC Medical Center 1200 N. State Street, Room 1011 Los Angeles, CA 90033 E-mail: [email protected]
Original Articles
Use of Therapeutic Hypothermia in Postcardiac Arrest Patients by Emergency Departments Dina Seif1 and Sean O. Henderson1,2
Since 2003, resuscitation guidelines have recommended the use of induced hypothermia as a therapy for patients who achieve return of spontaneous circulation after cardiac arrest from ventricular fibrillation. The aim of this study was to survey emergency physicians across the United States on their use of therapeutic hypothermia (TH) after cardiac arrest. An 18-question survey was e-mailed to a sample of emergency physicians. Fifty-eight respondents completed the survey. Most (71%) were associated with an emergency medicine residency training program. Annual census ranged from 12,000 to >170,000 visits. TH is used by the majority (69%) of respondents, 79% of which report the presence of a formal institutional protocol. The majority of respondents use TH in arrest rhythms including but not limited to ventricular fibrillation, and 21% begin the process in the prehospital setting. To induce hypothermia, a majority of respondents use commercial cooling products. The average time to target temperature was 95 minutes. The majority of respondents report a goal temperature between 328C and 348C. A shivering protocol is used by 76% of respondents, and as a first line medication, 46% use benzodiazepines. For those who do not use TH or do not have a protocol in place, the reasons cited include ‘‘too expensive,’’ ‘‘too difficult to implement,’’ and ‘‘not enough science to warrant it.’’ In this sample of practicing emergency physicians, TH after cardiac arrest is not being used as described in the original literature. Although awareness and implementation of TH have increased, there appears to be a wide variation in the application of this therapy.
committees and Task Forces of the American Heart Association, 2005). Large, multicenter, randomized, controlled trials will be necessary to investigate the utility of therapeutic hypothermia (TH) in postarrest resuscitation. The first step to this process is analyzing experiences, opinions, and current applications of TH in emergency departments across the United States. A survey of practicing emergency physicians was created to gain insight into the types of patients selected, what devices and techniques are being employed, and how hospital-wide protocols are being developed. Only by understanding the barriers to implementing this therapy we can begin to develop and adjust critical pathway protocols for widespread use.
Introduction
S
urvival and favorable neurologic recovery are uncommon after cardiac arrest, likely because of mechanisms of cerebral injury caused by brain anoxia and the resulting inflammatory cascades that follow. In 2002, two separate randomized controlled studies demonstrated that induced hypothermia after cardiac arrest from ventricular fibrillation (VF) improved neurologic outcomes (Bernard et al., 2002; Hypothermia after Cardiac Arrest Study Group, 2002). Prior to these findings, standard postcardiac resuscitation was directed at preventing dysrhythmias and providing circulatory support without any specific therapy to limit neurologic damage. The current guidelines from the Advanced Life Support Task Force of the International Liaison Committee on Resuscitation (ILCOR) recommend that unconscious adult patients with spontaneous circulation after out-of-hospital cardiac arrest should be cooled to 328C–348C for 12–24 hours when the initial rhythm is VF (ECC Committee and Sub-
Methods The study protocol was approved by the University of Southern California Institutional Review Board.
Departments of 1Emergency Medicine and 2Preventive Medicine, Keck School of Medicine of the University of Southern California, Los Angeles, California.
23
24
SEIF AND HENDERSON Table 1. Demographic Data
Study design This is a cross-sectional descriptive study of the use of TH after return of spontaneous circulation (ROSC) postcardiac arrest in emergency departments across the United States. These findings are based on survey responses collected between January 2009 and April 2009. Enrollment The authors recruited a diverse sample of emergency physicians from different clinical practice settings across the United States, which included alumni of a large inner-city residency program and members of the SAEM Research Directors Interest Group. E-mail invitations were sent to 100 emergency physicians. Survey An 18-question, Internet-based survey was created consisting of Likert scales, categorical responses, single answers, and multiple choice. The survey had five separate categories: physician demographic data, emergency department characteristics, use of TH including patient selection and prehospital care, methods for TH including shivering protocol, and opinions on TH. Results The response rate was 58%. Two responses from emergency medical systems representatives were excluded as they were not specific to any particular emergency department. A third response from a non-emergency physician was excluded.
No. (%) of responses ED characteristics Private Public University Public university Kaiser Veterans administration Private public ED censusa 25,000 or less 25,001–50,000 50,001–75,000 75,001–100,000 100,001–125,000 More than 125,000 Emergency medicine residency Yes No
23 12 12 4 2 1 1
(41.8) (21.8) (21.8) (7.3) (3.6) (1.8) (1.8)
2 14 23 10 3 1
(3.8) (26.4) (43.4) (18.9) (5.6) (1.9)
39 (70.9) 16 (29.1)
a Emergency department (ED) census was not provided by two institutions.
reported protocols being developed by multidisciplinary teams involving various departments and nursing (Table 3). Twenty-one percent initiate TH in the prehospital setting. Indications Seventy-six percent of respondents use TH in all cardiac arrest patients who achieve ROSC, including, but not limited to, VF. Ten percent use it in patients with ROSC only after VF.
Demographics Survey participants represented 18 states across the country. Respondents represented a good distribution of practice environments including private, public, and university hospitals (Fig. 1). The majority of respondents were associated with an emergency medicine residency training program. Annual census ranged from 12,000 to 170,000, with an average of 66,000. Table 1 summarizes the demographics of respondents. Thirty-one percent of respondents to the survey do not use TH after cardiac arrest. Reasons for nonuse are listed in Table 2. TH is used by 69% of respondents, with 79% of these reporting a formal TH protocol at their institution. Over half of respondents reported that their TH protocol was always initiated in the emergency department. Forty-two percent
Cooling methods A wide variety of cooling techniques exist. Most respondents use a commercial product (Fig. 2) to achieve hypothermia. The average goal time to reach target temperature is 115 minutes, with a range of 20–240 minutes. The majority use a target temperature between 328F and 348F. Only one respondent reported a target temperature outside the ILCOR recommended range at 288C.
Table 2. Use of Therapeutic Hypothermia and Reasons for Nonuse No. (%)
60%
Private
40%
Public
92%
University
75%
EM residency No residency
FIG. 1.
8% 25%
82% 38%
18% 63%
Distribution of therapeutic hypothermia use.
Yes No Protocol development in process Not enough scientific evidence Have not been able to agree on a protocol Have not thought about it Too complicated/difficult Not part of ACLS Resistance from other departments Not used locally Too expensive Respondents were allowed multiple responses. ACLS, actual cardiac life support.
38 17 5 5 5 5 4 3 2 1 1
(69.1) (30.9) (29.4) (29.4) (29.4) (29.4) (23.5) (17.6) (11.7) (5.9) (5.9)
THERAPEUTIC HYPOTHERMIA IN THE ED
25
Table 3. Therapeutic Hypothermia Characteristics
Percentage of respondents 0%
No. (%) of responses 30 (78.9) 5 (13.2) 20 (52.6) 14 (36.8) 1 (2.6)
Participants were asked how they felt about the following statement: ‘‘Therapeutic hypothermia improves survival and promotes a better neurologic outcome in the cardiac arrest patient.’’ Forty-seven of the participants strongly agreed with
Cooling methods.
80%
71%
45% 13% 32% 3%
None
3%
Discussion
70%
3%
Propofol Combination
(10.5) (55.3) (15.8) (2.6)
Opinions
50% 60% 55%
Paralytic
4 21 6 1
Seventy-six percent of respondents have a protocol to address and prevent shivering. The majority use benzodiazepines and/or paralytics, with benzodiazepines being the most popular as a first-line medication (Fig. 3). One respondent reported using propofol as a first-line medication to prevent shivering.
40%
71%
Benzodiazepene Opiate
FIG. 3.
Shivering protocols
FIG. 2.
Propofol
(40) (34.3) (11.4) (5.7) (2.9)
a Thirty-five of 38 respondents who use TH answered whether they had a protocol and how often it was initiated in the ED. Respondents were allowed multiple responses regarding protocol development. TH, therapeutic hypothermia; EM, emergency medicine.
30%
Opiates Paralytics
14 12 4 2 1
8 (21.1) 28 (73.7)
20%
Benzodiazepenes
First Line Medication
Official hypothermia protocola Yes No How often TH is initiated in the EDa Always Sometimes Never TH protocol created by Multidepartments EM Pulmonary critical care Neurology Cardiology Frequency of use Weekly Monthly Once every 3 months Once a year Prehospital TH Yes No
10%
3%
Use of paralytics and sedatives to prevent shivering.
this statement, 35% somewhat agreed, 7% were neutral, and 2% somewhat disagreed.
Implementation of TH in emergency departments has been slow despite treatment recommendations from ILCOR since 2003. A study surveying emergency physicians, cardiologists, and critical care physicians in 2005 found that only 13% had ever used TH after cardiac arrest (Abella et al., 2005). Reasons cited included the perception that TH is difficult to accomplish, requires large amounts of resources, and carries dangerous side effects. The use of TH in arrest rhythms other than VF, such as pulseless electrical activity (PEA) or asystole, has not been well studied and there have been no large studies examining the use of TH after primary respiratory failure, trauma, drowning, hanging, in-hospital arrests, or pediatric arrests. The current ILCOR recommendations are based on findings from studies of cardiac arrest due to VF or nonperfusing VT (Bernard et al., 2002; Hypothermia after Cardiac Arrest Study Group, 2002). Our survey found that many emergency physicians appear to be using TH regardless of the arrest rhythm. Non-VF dysrhythmias are the most common in cardiac arrest, but they have the poorest outcomes (Stratton and Niemann, 1998). It does not seem unreasonable to apply TH to survivors of asystolic or PEA arrest because the mechanisms by which hypothermia is postulated to improve neurologic outcomes after anoxic brain injury should not differ based on the cause of the arrest. To date, this concept has no support in the literature (Oddo et al., 2006; Don et al., 2009). One study found that asystolic and PEA arrests had longer times to ROSC compared with VF/VT, and poor outcomes in this setting were not altered by TH (Oddo et al., 2006). In initial human studies, TH appeared to improve survival even when delayed hours after resuscitation (Bernard et al., 2002; Hypothermia after Cardiac Arrest Study Group, 2002). Animal studies, however, have found that a delay in hypothermia after ROSC as short as 15 minutes negates the benefit of TH (Kuboyama et al., 1993). There are no data from randomized, controlled studies that addresses whether outcomes in humans could be improved by decreasing time between ROSC and hypothermic target temperature. However, time to achieve hypothermia was an independent predictor of good neurologic outcome in one study, with every hour delay leading to a 31% decrease in likelihood for favorable neurologic recovery (Wolff et al., 2009). A recent study evaluating the use of a conductive-immersion surface cooling device
26 achieved rapid cooling times averaging 37 minutes (Howes et al., 2010) and reported survival and neurologic function that were superior to those from randomized, controlled trials with cooling times averaging 120–480 minutes. The physicians in our survey reported an average goal time to reach target temperature within 2 hours from ROSC; however, the range was quite large (20–240 minutes). Only half of the respondents in this survey start the hypothermia process in the emergency department, which highlights the importance of cooperation with intensive care units and critical care physicians in the management of postarrest resuscitation. More importantly, it raises the question of whether survival and neurologic outcome can be improved if hypothermia was initiated in the emergency department or perhaps even in the prehospital setting. The protocol described by an Australian group initiated cooling measures during transport to the emergency department (Don et al., 2009), but our survey found that most emergency medical systems had not yet incorporated TH into the prehospital setting. Rapid infusion of 48C crystalloid has been shown to be relatively easy, safe, and effective in achieving mild hypothermia after hospital arrival (Kim et al., 2005, 2007; Kamarainen et al., 2008). There may be additional benefit to initiating hypothermia prior to emergency department (ED) arrival, even as early as the arrest period prior to ROSC. Animal data suggest that intra-arrest hypothermia may improve the success of defibrillation (Boddicker et al., 2005) and that benefits of TH are only seen when initiated immediately after ROSC (Kuboyama et al., 1992, 1993). Most respondents to our survey use a target range of 328C– 348C as recommended by ILCOR and the majority have specific shivering protocols to sedate or paralyze patients to decrease energy and oxygen demands. Surprisingly, several institutions describe the use of paralytics as first-line medications without associated sedation. It is known that hypothermia reduces the clearance of medications that are metabolized by the cytochrome P450 system (Tortorici et al., 2007), such as those used in many shivering protocols. However, data are lacking in terms of efficacy and safety of specific medications in this setting. The optimal cooling techniques for induction, maintenance, and reversal of TH have yet to be described and validated. Commercial products are increasingly used to achieve hypothermia in the emergency department. Products used by respondents to this study ranged from invasive central catheters to simple cooling blankets, and a large number of physicians reported using commercial products in combination with traditional cooling methods such as ice bags and cooled saline. Although advances in technology and availability of new products have made the process of cooling easier to induce and maintain, there are limited data comparing the use of specific products. The cost of invasive devices is even higher when the additional expense of physician and nursing time are factored in. Barriers In evaluating the barriers to implementation of TH, we can apply a framework originally created by Cabana et al. (1999) and adapted to the subject of TH by Brooks and Morrison (2008). Using seven general categories, Brooks identified specific obstacles to changing knowledge, attitudes, and
SEIF AND HENDERSON behavior in the care of postcardiac arrest patients. Applying this framework to our results, we found several major themes in the challenges to TH implementation among respondents to our survey. There appears to be a lack of awareness and familiarity with TH despite recommendations from ILCOR and AHA. Five of 17 respondents answered ‘‘have not thought about it’’ as a reason for they do not use TH, demonstrating a disconnect from advisory statements and guidelines by international and national health agencies. Respondents who reported TH ‘‘is not used locally’’ are entrenched in the inertia of previous practice. Lack of agreement manifests as skepticism of research findings and concerns about adverse effects. Despite two randomized, controlled trials, the number of patients studied is relatively small, long-term data are lacking, and the use of TH in arrest rhythms other than VF has not been well studied. Guideline-related barriers result from a lack of concrete protocols. Unlike the well-established, standardized, and highly protocolized algorithms for basic and advanced life support (BLS) and actual cardiac life support (ACLS), TH is not a core component of resuscitation curricula. Disagreement on protocols between departments, an example of interprofessional barriers, was a strong factor in this study for many respondents who do not use TH. Traditional postresuscitative care requires large amounts of physician and nursing time. The addition of a complex therapy requiring close monitoring and management poses an additional lack of self-efficacy barrier to those who perceive TH to be too complicated, time consuming, and difficult to accomplish. Finally, perhaps most critical is the lack of outcome expectancy in which there is a sense of futility for improved outcomes in comatose patients after cardiac arrest. Limitations Despite a relatively high response rate to this survey, the sample size is small and our findings may not be generalizable to all emergency departments in the United States. Respondents represented public, private, and university hospital settings; however, the majority were associated with emergency medicine teaching programs with academic emphases, which may skew our results. Regional differences may be reflected in our results because a large proportion of respondents practice in California. Additionally, the results of this study are subject to responder bias because emergency physicians who currently initiate hypothermia after cardiac arrest or have an interest in doing so are more likely to have responded to our survey. Conclusion It appears that emergency physicians are gradually incorporating TH into their clinical practice when resuscitating patients who achieve ROSC after cardiac arrest. However, TH is not being used as described in the original literature, and it is not being used uniformly across emergency departments. Therapeutic targets differ in terms of target temperature and cooling times, and medications to prevent shivering vary tremendously. Such disparity underscores the need for large, multicenter validation studies to establish the optimal methods for inducing and maintaining hypothermia. Until such guidelines exist, it is the responsibility of departments and
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Address correspondence to: Sean O. Henderson, M.D. Department of Emergency Medicine LAC þ USC Medical Center 1200 N. State Street, Room 1011 Los Angeles, CA 90033 E-mail: [email protected]
