- Email: [email protected]
Survival From In-hospital Cardiac Arrest on the Internal Medicine Clinical Teaching Unit
Canadian Journal of Cardiology 29 (2013) 117–121
Clinical Research
Survival From In-hospital Cardiac Arrest on the Internal Medicine Clinical Teaching Unit Blair C. Schwartz, MDCM,a Dev Jayaraman, MDCM, MPH,a,b and Paul J. Warshawsky, MDCMb,c a b
Division of General Internal Medicine, McGill University, Montreal, Québec, Canada
Department of Adult Critical Care, Jewish General Hospital, Montreal, Québec, Canada c
Division of Pulmonary Medicine, Jewish General Hospital, Montreal, Québec, Canada
ABSTRACT
RÉSUMÉ
Background: There is a paucity of data on patient outcomes following in-hospital cardiac arrest (IHCA) on the Internal Medicine clinical teaching unit (CTU). Accurate outcome data enhances discussions between patients, surrogates, and physicians, and assists in their management. Methods: We performed a retrospective cohort study of consecutive “Code Blue” calls on 2 medical CTUs in a Canadian tertiary centre from January 1, 2003 to June 30, 2007. The medical records of identified patients were screened for eligibility and patient-specific and arrestspecific data were collected for eligible events. Primary outcome was survival to hospital discharge. Results: Our cohort comprised 83 patients; including 54 (65.1%) men with a mean age of 75 years (range, 38-97). Infection (34.9%) was the principal reason for admission and over half of patients had 3 or more comorbid illnesses. Forty-three (51.8%) of the IHCA events were witnessed. In all, 39 (90.7%) of the witnessed and 36 (90%) of the unwitnessed arrests were pulseless electrical activity (PEA) or asystole (P ⫽ not significant). Return of spontaneous circulation occurred in 29 patients (34.9%) and 2 (2.4%) survived to hospital discharge. No patients survived to discharge after unwitnessed arrest. Conclusions: IHCA in Internal Medicine CTU patients is characterized by a high rate of PEA/asystole and a minimal chance of survival to
Introduction : Les données sur l’évolution des patients à la suite d’un arrêt cardiaque intrahospitalier (ACIH) à l’unité d’enseignement clinique (UEC) en médecine interne sont peu nombreuses. Des données précises sur l’évolution favorisent les échanges entre les patients, les proches et les médecins, et les assistent dans la conduite à tenir. Méthodes : Nous avons réalisé une étude rétrospective de cohortes pour des appels consécutifs associés au code bleu à 2 UEC médicales d’un centre tertiaire canadien du 1er janvier 2003 au 30 juin 2007. Les dossiers médicaux des patients identifiés ont été examinés pour évaluer l’admissibilité, et des données propres à chacun des patients et à l’arrêt cardiaque ont été recueillies pour les événements admissibles. Le principal résultat a été la survie du patient à la sortie de l’hôpital. Résultats : Notre cohorte de 83 patients comprenait 54 (65,1 %) hommes dont l’âge moyen était de 75 ans (étendue, 38-97). L’infection (34,9 %) a été la raison principale de l’admission, et plus de la moitié des patients ont eu 3 affections comorbides ou plus. Quarante-trois (43; 51,8 %) des ACIH ont été confirmés. Dans l’ensemble, 39 (90,7 %) arrêts confirmés et 36 (90 %) arrêts non confirmés ont démontré une activité électrique sans pouls (AÉSP) ou une asystole (P ⫽ non significatif). Le retour à une circulation spontanée est apparu chez 29 patients (34,9 %), et 2 (2,4 %) ont survécu à la sortie de
In-hospital cardiac arrest (IHCA) remains one of the most stressful events for healthcare providers, patients, and family members during a hospital admission. Since the first formal descriptions of cardiopulmonary resuscitation (CPR) over 50 years ago,1,2 reanimation attempts have, in many jurisdictions, become the default for all hospitalized patients with
physicians requiring patient or surrogate consent to withhold resuscitation. As part of a meaningful code status discussion, the physician should provide accurate information regarding the likelihood of survival from a resuscitation event.3 Such information is crucial for all parties in order to permit informed decision-making and has been shown to influence patient’s preferences regarding resuscitation attempts.4-6 Several large recent studies have addressed survival rate from IHCA, but they have been dominated by patients admitted to a critical care setting.7-10 This environment, selected patient demographic, and admitting diagnosis may have an effect on arrest etiology and chance of survival. Previous IHCA survival studies have found that patients on
Received for publication December 6, 2011. Accepted March 30, 2012. Corresponding Author: Dr Blair Carl Schwartz, Jewish General Hospital, Division of General Internal Medicine, 3755 Cote Sainte Catherine, Room G-050, Montreal, Québec H3T 1E2, Canada. Tel.: ⫹1-514-340-8222 ⫻4974; fax: ⫹1-514-340-7905. E-mail: [email protected] See page 121 for disclosure information.
0828-282X/$ – see front matter © 2013 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.cjca.2012.03.024
118
Canadian Journal of Cardiology Volume 29 2013
hospital discharge. Moreover, no patient with an unwitnessed arrest survived to hospital discharge. While these findings require confirmation in a larger study, they merit consideration in the context of code status discussions, particularly with respect to the response to unwitnessed arrests.
l’hôpital. Aucun patient n’a survécu à la sortie après un arrêt non confirmé. Conclusions : L’ACIH des patients à l’UEC en médecine interne est caractérisé par un taux élevé d’AÉSP ou d’asystole, et d’une chance de survie minime à la sortie de l’hôpital. De plus, aucun patient ayant eu un arrêt non confirmé n’a survécu à la sortie de l’hôpital. Bien que ces conclusions doivent être confirmées par une plus vaste étude, elles méritent d’être prises en considération dans le cadre de discussions sur les codes, particulièrement en ce qui concerne la réponse aux arrêts non confirmés.
general wards tended to have lower survival rates than those in monitored settings.11-15 No studies to date have specifically examined the IHCA population of General Internal Medicine patients, who are likely to be older, have more extensive comorbidities, and require admission with a higher case complexity and burden of illness than other ward populations. These patient differences combined with the clinical teaching unit (CTU) milieu, make for a unique population for whom we are unaware of any IHCA survival data. We thus conducted a retrospective cohort study to determine the survival rate after cardiac arrest for patients admitted to 2 Internal Medicine CTUs in a Canadian tertiary centre.
events that met the inclusion criteria, the medical record was abstracted for the predefined patient, resuscitation, and outcome variables using a standardized data collection form. We defined return of spontaneous circulation (ROSC) using the Utstein guideline definition of any palpable central pulse for longer than 20 minutes without chest compressions.16 Patients who achieved ROSC were then further assessed as to whether they survived to be transferred to a critical care area, or survived to be discharged from hospital. Patient demographics and clinical information were obtained from the CTU admission note. Arrest characteristics and outcome data were obtained from the cardiac arrest form completed by the senior Internal Medicine house staff of the resuscitation team. All data abstraction was performed by the primary author (B.C.S.). In the event of uncertainty regarding cardiac arrest classification, this was discussed with a second author (P.J.W.) to obtain consensus. The main outcome of this study was survival to hospital discharge. We also studied the rate of ROSC, and rate of survival to a Critical Care area. Outcomes were analyzed by witnessed vs unwitnessed arrest status. STATA (version 10; Statacorp, College Station, TX) 2 test was performed to evaluate statistical significance of groups when appropriate. The study was approved by the hospital’s Research Ethics Committee.
Methods We performed a retrospective cohort study of all consecutive patients who experienced a cardiac arrest while admitted to an Internal Medicine CTU in a 637 bed tertiary care hospital affiliated with McGill University, Montreal, Canada. The hospital has 2 Internal Medicine CTU wards, with a combined census of 70 patients. In the event of a cardiac arrest or need for urgent medical attention, all personnel are trained to call a “Code Blue,” in response to which an announcement is made overhead and a page is sent to the resuscitation team. This team is fully Advanced Cardiac Life Support trained and staffed by senior Internal Medicine house staff, Critical Care Registered Nurses, and Registered Respiratory Therapists. All Advanced Cardiac Life Support medications, manual defibrillators, and advanced airway equipment were available on each of the 2 CTUs. There was no medical emergency team in the institution. We established our cohort by obtaining a list from the operator of all consecutive Code Blue calls between January 1, 2003 and June 30, 2007 and identified events taking place on the 2 Internal Medicine CTUs. This list was then cross-referenced with the admission and discharge logs of that unit in order to associate a patient with each event. Patients were associated when the death or transfer of a patient corresponded to the date, time, and location of the Code Blue call. When identified, we obtained the complete medical records of the patient and screened the resuscitation event for entry into the cohort. Patients were included if they were admitted to the Internal Medicine service at the time of the event and received chest compressions or electrical cardioversion in response to an absence of signs of circulation. Exclusion criteria included: patients under 20 years of age, events that were exclusively respiratory arrests, the existence of a Do Not Attempt Resuscitation order prior to the event, and resuscitation attempts that were aborted by family or the physician for nonclinical reasons. For
Results Between January 1, 2003 and June 30, 2007 there were 1185 Code Blue calls in the hospital, with 198 (16.7%) on the Internal Medicine CTUs. Details on cohort assembly and demographics are contained in Figure 1 and Table 1, respectively. Our cohort was 65.1% male with a mean age of 75 years (range, 38-97). Infection was the most frequent reason for hospital admission (34.9%), with cancer and cardiovascular causes accounting for similar frequencies of admission at 13.3% and 12% of admissions, respectively. Fifty-three percent of patients had 3 or more comorbid medical conditions at the time admission, including 26.5% with an active malignancy (Table 1). Of the 83 cardiac arrests, 43 (51.8%) were witnessed at the time of the event (Table 2). Pulseless electrical activity (PEA) or asystole was the first rhythm documented by the arrest team in 90.4% of the events. The presenting rhythm did not differ between witnessed and unwitnessed events (P ⫽ 1). While an increased proportion of unwitnessed cardiac arrests was observed between 23:30 and 07:29 compared with other time periods (Table 2), the difference was not statistically significant (P ⫽ 0.157).
Schwartz et al. Internal Medicine Cardiac Arrest Survival
119
CTU Code Blue calls, N = 198 • Cancelled calls, n = 14 (7.1%) • Unidenfied calls, n = 36 (18.2%) • Incomplete medical record, n = 1 (0.5%) Code Blue calls reviewed, n = 147
Cardiac Arrest No resuscitaon aempted n = 22 (15%) • Paent DNAR, n = 19 • Considered fule, n = 3
Cardiac Arrest Aempted resuscitaons n = 83 (56.5%) Presenng rhythm: • VF/VT, n = 8 (9.6%) • Non-VF/VT, n = 75 (90.4%)
Noncardiac Arrest n = 42 (28.6%) • Respiratory arrest, n = 17 • Sepsis, n = 13 • Other (GI bleed, seizure), n = 12
Figure 1. Cohort Utstein-style flow sheet. CTU, Clinical Teaching Unit; DNAR, Do Not Attempt Resuscitation; GI, gastrointestinal; VF/VT, ventricular fibrillation/ventricular tachycardia.
Overall, 34.9% of cardiac arrests achieved ROSC, with 28.9% surviving to be transferred to a critical care area, and 2.4% surviving to hospital discharge. Of the 40 unwitnessed cardiac arrests none survived to hospital discharge.
Table 1. Cohort demographics n (%) Age (y) ⬍ 50 51-60 61-70 71-80 ⬎ 81 Sex Male Admission diagnosis Infection/sepsis Cancer or related Cardiac (MI, CHF, or arrhythmia) Gatrointestinal bleed Renal disease COPD Diabetes Stroke Other Comorbidity Hypertension Diabetes mellitus Coronary artery disease Active malignancy Heart Failure Renal disease COPD Dementia Treated remote malignancy Stroke/TIA Angina pectoris Peripheral arterial disease Valvular heart disease Rheumatic disease Previous cardiac arrest Cardiomyopathy
4 (4.8) 7 (8.4) 15 (18.1) 26 (31.3) 31 (37.3) 54 (65.1) 29 (34.9) 11 (13.3) 10 (12.0) 6 (7.2) 5 (6.0) 4 (4.8) 2 (2.4) 1 (1.2) 15 (18.1) 50 (60.2) 27 (32.5) 23 (27.7) 22 (26.5) 17 (20.5) 17 (20.5) 14 (16.9) 13 (15.7) 11 (13.3) 9 (10.8) 5 (6.0) 5 (6.0) 2 (2.4) 2 (2.4) 1 (1.2) 1 (1.2)
CHF, congestive heart failure; COPD, chronic obstructive pulmonary disease; MI, myocardial infarction; TIA, transient ischemic attack.
Discussion To our knowledge, this study represents the first to address the survival from IHCA of patients admitted to an Internal Medicine CTU. The ROSC rate in our study is comparable with the reported rates from recent cardiac arrest studies (Table 3). However, the rate of survival to hospital discharge in our cohort was lower than has been reported recently. This difference may be explained by factors unique to the general Internal Medicine population and setting. Meaney et al. reported on 51,919 arrests from the National Registry of Cardiopulmonary Resuscitation (NRCPR);7 it should be noted that 48% of their events occurred in an intensive care unit (ICU), 44% of patients were admitted with a cardiac complaint and 79% of their events were characterized as witnessed; this likely explains the differences in the rates of ventricular fibrillation/ventricular tachycardia (VF/VT) and survival to hospital discharge when compared with our cohort. Even when analysis of this registry was restricted to unwitnessed/unmonitored IHCA the rate of survival to hospital discharge (8%) was higher than seen in our cohort.17 Brindley et al. reported on 218 consecutive IHCA events occurring among unmonitored adult in-patients.18 Our Internal Medicine population, however, was considerably older, with 68% of patients older than the age of 70 compared with 46% in Brindley’s study. In addition, the non-Internal Medicine patients in Brindley’s cohort would be expected to have a higher incidence of readily and persistently treatable cardiac arrest etiologies such as postoperative myocardial infarction, hemorrhage, or pulmonary embolism. As well, elective surgery patients have been previously shown to have a higher rate of successful resuscitation after IHCA.19 Our study does, however, confirm Brindley’s and others observation that patients with an unwitnessed cardiac arrest outside of a monitored area did not survive to hospital discharge.14 That the worse outcome after IHCA found in our Internal Medicine population is related to setting, comorbidity, and underlying reason for admission is in keeping with the results of Larkin and colleagues who analyzed the NRCPR cohort for preresuscitation factors associated with mortality.20 They found that
120
Canadian Journal of Cardiology Volume 29 2013
Table 2. Arrest characteristics and outcome Outcome
Total n⫽83 (%) Witnessed n⫽43 (%) Unwitnessed n⫽40 (%)
Initial rhythm
ROSC
ROSC, survived to ICU
ROSC, survived to discharge
VF/VT
29 (34.9) 18 (41.8) 11 (27.5)
24 (28.9) 14 (32.5) 10 (25)
2 (2.4) 2 (4.7) 0 (0)
8 (9.6) 4 (9.3) 4 (10)
Time of day
PEA/ asystole 75 (90.4) 39 (90.6) 36 (90) P ⫽ 1*
07:30-15:29
15:30-23:29
23:30-07:29
29 (34.9) 18 (41.8) 11 (27.5)
27 (32.5) 18 (41.8) 9 (22.5)
27 (32.5) 7 (16.3) 20 (50) P ⫽ 0.157†
ICU, intensive care unit; PEA, pulseless electrical activity; ROSC, return of spontaneous circulation; VF, ventricular fibrillation; VT, ventricular tachycardia. * Comparison of PEA/asystole between witnessed and unwitnessed. † Comparison of events between 23:30 and 07:30 between witnessed and unwitnessed.
advanced age, noncardiac nonsurgical admission, and arrest on a general ward are associated with worse outcome. In particular, pre-existing malignancy, a common condition in Internal Medicine CTU patients and present in 26.5% of our cohort, was associated with a nearly 2-fold increase in the risk of death. To further examine the difference in hospital survival between Internal Medicine and non-Internal Medicine IHCA events we conducted a review of patients admitted to our own institution’s ICU with a diagnosis of IHCA from wards other than the 2 Internal Medicine CTUs. In 2008, 24 such patients were admitted to the ICU with a survival rate to hospital discharge of 29.2%. This would approximate a survival rate from the non-Internal Medicine ward of 8.5% that is on par with previous general ward-based studies and 3.5 times higher than seen in our cohort, further supporting our findings.13,17,18 The frequency of PEA/asystole (90%) in our cohort is higher than has been reported in many studies of IHCA and this distribution was not different between witnessed and unwitnessed events. In part, this may be because, while our cohort had a frequent history of cardiac comorbidities and risk factors, relatively few patients (12%) were admitted with a primary cardiac diagnosis. An IHCA population admitted with pneumonia and similar cardiovascular burden to our cohort reported a 14.7% VF/VT rate and only 4.7% of events attributable to myocardial ischemia.21 It is thus likely that many patients in our cohort arrested as a result of progression of their underlying disease,22 rather than experiencing a sudden cardiac event. These patients are likely to present as PEA/asystole,23 and this would further explain the low rate of survival to hospital discharge. Moreover, processes that lead to PEA/asystole such as hypoxemia and respiratory failure, which are common antecedents of arrest in the Internal Medicine setting,24 are likely to be recognized late in the ward setting. It should be noted that our institution did not have a high dependency unit or a medical emergency team during the study period and this is an important fact in applying our results to clinical practice. While it remains controversial if these elements can reduce the incidence of, or improve survival from cardiac arrest,5,6,17 they are essential in the management of acute noncardiac arrest, life-threatening events, which constituted 28.6% of code
blue calls in our cohort. Thus the risk of harm exists if these patients fail to receive appropriate medical attention due to a Do Not Attempt Resuscitation order. As such our hospital uses a multitiered level of intervention status. We use level 1 and 4 to reflect full supportive measures and palliative therapy respectively. Level 2 patients would have the cardiac arrest team called to provide care as needed, including transfer to the ICU. At this care level patients and providers can set limitations on particular life support options, including their desire for CPR in the case of IHCA. Level 3 patients receive maximal therapy that can be provided on a ward, and are not candidates for transfer to a critical care area. We have found that this system, in conjunction with accurate prognostic information, helps to facilitate these difficult discussions. When deciding about intervention status, patients and their surrogates often receive information about the chance of surviving the event; that the majority of medical CTU patients who are resuscitated from IHCA will die despite admission to a Critical Care area is also relevant to this decision, and to decisions made after “successful” resuscitation. It is likely this knowledge will affect preferences with regard to CPR, post-IHCA management and in turn impact resource utilization. This study is limited by its small cohort size and single centre nature which reduces its generalizability. As well we were unable to identify the patients associated with 19.6% of the Code Blue calls on the 2 CTUs due to the retrospective nature of the study and manner in which cardiac arrest records are maintained. It is highly unlikely that any patient who remained on the ward after a Code Blue call would have met our definition for inclusion in this cohort. A more probable explanation is that these Code Blue calls were due to events other than cardiac arrest, such as syncope or hypoglycemia; such events would not result in death or Critical Care transfer and thus would not be identifiable using our methodology. It is also possible that some Code Blue calls were made for hospital visitors rather than admitted patients, as is the practice in our institution. It is unlikely that a significant number of actual cardiac arrests were missed. It should also be noted that no patients in our cohort were treated with therapeutic hypothermia (TH) post ROSC. TH has been associated with improved outcomes after out of hospital ar-
Table 3. Comparison with other study cohorts
Current Study (2011) Meaney et al. (2010)7 Brindley et al. (2002)18
n
ROSC (%)
Survival to hospital discharge (%)
VF/VT (%)
83 51,919 218
34.9 47.6 29
2.4 17.6 8
9.6 24.1 30
ROSC, return of spontaneous circulation; VF, ventricular fibrillation; VT, ventricular tachycardia.
Schwartz et al. Internal Medicine Cardiac Arrest Survival
121
rests with a shockable rhythm,25 possibly on a neuroprotective basis or due to decreased size of myocardial infarction.26 Improved outcomes however have not been demonstrated with the use of TH in the IHCA population.24,27 This may reflect the different nature of IHCA events or the lack of appropriately powered studies in this unique population. The results of our study would need to be re-evaluated should future studies of IHCA management demonstrate a significant impact on survival. In conclusion cases of IHCA in patients admitted to the Internal Medicine CTU of our hospital represent a unique population in whom we demonstrated a high rate of PEA/asystole and low rate of survival to hospital discharge, possibly on the basis of severe underlying conditions. The absence of survivors to hospital discharge after an unwitnessed arrest in this population should be taken into account when responding to cardiac arrests of this nature and caring for these patients in the Coronary Care Units or ICUs. We would recommend a larger, multi-centre prospective review of IHCA in Internal Medicine in-patients to further establish survival rates for use in code status discussions in this important and unique population.
11. Gwinnutt CL, Columb M, Harris R. Outcome after cardiac arrest in adults in UK hospitals: effect of the 1997 guidelines. Resuscitation 2000; 47:125-35.
Acknowledgements The authors thank Dr Vicky Tagalakis for her critical review of a previous version of this manuscript.
17. Brady WJ, Gurka KK, Mehring B, Peberdy MA, O’Connor RE. In-hospital cardiac arrest: impact of monitoring and witnessed event on patient survival and neurologic status at hospital discharge. Resuscitation 2011; 82:845-52.
Disclosures The authors have no conflicts of interest to disclose.
18. Brindley PG, Markland DM, Mayers I, Kutsogiannis DJ. Predictors of survival following in-hospital adult cardiopulmonary resuscitation. CMAJ 2002;167:343-8.
References
19. Burns R, Graney MJ, Nichols LO. Prediction of in-hospital cardiopulmonary arrest outcome. Arch Intern Med 1989;149:1318-21.
1. Kouwenhoven WB, Jude JR, Knickerbocker GG. Closed-chest cardiac massage. JAMA 1960;173:1064-7. 2. Safar P, Brown TC, Holtey WJ, Wilder RJ. Ventilation and circulation with closed-chest cardiac massage in man. JAMA 1961;176:574-6. 3. Frank C, Heyland DK, Chen B, et al. Determining resuscitation preferences of elderly inpatients: a review of the literature. CMAJ 2003;169: 795-9.
12. Herlitz J, Bang A, Aune S, et al. Characteristics and outcome among patients suffering in-hospital cardiac arrest in monitored and non-monitored areas. Resuscitation 2001;48:125-35. 13. Tunstall-Pedoe H, Bailey L, Chamberlain DA, et al. Survey of 3765 cardiopulmonary resuscitations in British hospitals (the BRESUS Study): methods and overall results. BMJ 1992;304:1347-51. 14. Hershey CO, Fisher L. Why outcome of cardiopulmonary resuscitation in general wards is poor. Lancet 1982;1:31-4. 15. Peatfield RC, Sillett RW, Taylor D, McNicol MW. Survival after cardiac arrest in hospital. Lancet 1977;1:1223-5. 16. Cummins RO, Chamberlain D, Hazinski MF, et al. Recommended guidelines for reviewing, reporting, and conducting research on in-hospital resuscitation: the in-hospital ’Utstein style’. A statement for healthcare professionals from the American Heart Association, the European Resuscitation Council, the Heart and Stroke Foundation of Canada, the Australian Resuscitation Council, and the Resuscitation Councils of Southern Africa. Resuscitation 1997;34:151-83.
20. Larkin GL, Copes WS, Nathanson BH, Kaye W. Pre-resuscitation factors associated with mortality in 49,130 cases of in-hospital cardiac arrest: a report from the National Registry for Cardiopulmonary Resuscitation. Resuscitation 2010;81:302-11.
4. Jones GK, Brewer KL, Garrison HG. Public expectations of survival following cardiopulmonary resuscitation. Acad Emerg Med 2000;7:48-53.
21. Carr GE, Yuen TC, McConville JF, et al. American Heart Association’s Get With the Guidelines-Resuscitation (National Registry of CPR) Investigators. Early cardiac arrest in patients hospitalized with pneumonia: a report from the American Heart Association’s Get With The GuidelinesResuscitation Program. Chest 2012;141:1528-36.
5. DeVita MA, Braithwaite RS, Mahidhara R, et al. Use of medical emergency team responses to reduce hospital cardiopulmonary arrests. Qual Saf Health Care 2004;13:251-4.
22. Yokoyama H, Yonemoto N, Yonezawa K, et al. Report from the Japanese registry of CPR for in-hospital cardiac arrest (J-RCPR). Circ J 2011;75: 815-22.
6. Hillman K, Chen J, Cretikos M, et al. Introduction of the medical emergency team (MET) system: a cluster-randomised controlled trial. Lancet 2005;365:2091-7.
23. Weil MH, Fries M. In-hospital cardiac arrest. Crit Care Med 2005; 33:2825-30.
7. Meaney PA, Nadkarni VM, Kern KB, et al. Rhythms and outcomes of adult in-hospital cardiac arrest. Crit Care Med 2010;38:101-8.
24. Rittenberger JC, Guyette FX, Tisherman SA, et al. Outcomes of a hospital-wide plan to improve care of comatose survivors of cardiac arrest. Resuscitation 2008;79:198-204.
8. Fredriksson M, Aune S, Thoren AB, Herlitz J. In-hospital cardiac arrest–an Utstein style report of seven years experience from the Sahlgrenska University Hospital. Resuscitation 2006;68:351-8.
25. Bernard SA, Gray TW, Buist MD, et al. Treatment of comatose survivors of out-of-hospital cardiac arrest with induced hypothermia. N Engl J Med 2002;346:557-63.
9. Sandroni C, Ferro G, Santangelo S, et al. In-hospital cardiac arrest: survival depends mainly on the effectiveness of the emergency response. Resuscitation 2004;62:291-7.
26. Mottillo S, Sharma K, Eisenberg MJ. Therapeutic hypothermia in acute myocardial infarction: a systematic review. Can J Cardiol 2011;27:555-61.
10. Cooper S, Janghorbani M, Cooper G. A decade of in-hospital resuscitation: outcomes and prediction of survival? Resuscitation 2006;68:231-7.
27. Sandroni C, Nolan J, Cavallaro F, Antonelli M. In-hospital cardiac arrest: incidence, prognosis and possible measures to improve survival. Intensive Care Med 2007;33:237-45.
Clinical Research
Survival From In-hospital Cardiac Arrest on the Internal Medicine Clinical Teaching Unit Blair C. Schwartz, MDCM,a Dev Jayaraman, MDCM, MPH,a,b and Paul J. Warshawsky, MDCMb,c a b
Division of General Internal Medicine, McGill University, Montreal, Québec, Canada
Department of Adult Critical Care, Jewish General Hospital, Montreal, Québec, Canada c
Division of Pulmonary Medicine, Jewish General Hospital, Montreal, Québec, Canada
ABSTRACT
RÉSUMÉ
Background: There is a paucity of data on patient outcomes following in-hospital cardiac arrest (IHCA) on the Internal Medicine clinical teaching unit (CTU). Accurate outcome data enhances discussions between patients, surrogates, and physicians, and assists in their management. Methods: We performed a retrospective cohort study of consecutive “Code Blue” calls on 2 medical CTUs in a Canadian tertiary centre from January 1, 2003 to June 30, 2007. The medical records of identified patients were screened for eligibility and patient-specific and arrestspecific data were collected for eligible events. Primary outcome was survival to hospital discharge. Results: Our cohort comprised 83 patients; including 54 (65.1%) men with a mean age of 75 years (range, 38-97). Infection (34.9%) was the principal reason for admission and over half of patients had 3 or more comorbid illnesses. Forty-three (51.8%) of the IHCA events were witnessed. In all, 39 (90.7%) of the witnessed and 36 (90%) of the unwitnessed arrests were pulseless electrical activity (PEA) or asystole (P ⫽ not significant). Return of spontaneous circulation occurred in 29 patients (34.9%) and 2 (2.4%) survived to hospital discharge. No patients survived to discharge after unwitnessed arrest. Conclusions: IHCA in Internal Medicine CTU patients is characterized by a high rate of PEA/asystole and a minimal chance of survival to
Introduction : Les données sur l’évolution des patients à la suite d’un arrêt cardiaque intrahospitalier (ACIH) à l’unité d’enseignement clinique (UEC) en médecine interne sont peu nombreuses. Des données précises sur l’évolution favorisent les échanges entre les patients, les proches et les médecins, et les assistent dans la conduite à tenir. Méthodes : Nous avons réalisé une étude rétrospective de cohortes pour des appels consécutifs associés au code bleu à 2 UEC médicales d’un centre tertiaire canadien du 1er janvier 2003 au 30 juin 2007. Les dossiers médicaux des patients identifiés ont été examinés pour évaluer l’admissibilité, et des données propres à chacun des patients et à l’arrêt cardiaque ont été recueillies pour les événements admissibles. Le principal résultat a été la survie du patient à la sortie de l’hôpital. Résultats : Notre cohorte de 83 patients comprenait 54 (65,1 %) hommes dont l’âge moyen était de 75 ans (étendue, 38-97). L’infection (34,9 %) a été la raison principale de l’admission, et plus de la moitié des patients ont eu 3 affections comorbides ou plus. Quarante-trois (43; 51,8 %) des ACIH ont été confirmés. Dans l’ensemble, 39 (90,7 %) arrêts confirmés et 36 (90 %) arrêts non confirmés ont démontré une activité électrique sans pouls (AÉSP) ou une asystole (P ⫽ non significatif). Le retour à une circulation spontanée est apparu chez 29 patients (34,9 %), et 2 (2,4 %) ont survécu à la sortie de
In-hospital cardiac arrest (IHCA) remains one of the most stressful events for healthcare providers, patients, and family members during a hospital admission. Since the first formal descriptions of cardiopulmonary resuscitation (CPR) over 50 years ago,1,2 reanimation attempts have, in many jurisdictions, become the default for all hospitalized patients with
physicians requiring patient or surrogate consent to withhold resuscitation. As part of a meaningful code status discussion, the physician should provide accurate information regarding the likelihood of survival from a resuscitation event.3 Such information is crucial for all parties in order to permit informed decision-making and has been shown to influence patient’s preferences regarding resuscitation attempts.4-6 Several large recent studies have addressed survival rate from IHCA, but they have been dominated by patients admitted to a critical care setting.7-10 This environment, selected patient demographic, and admitting diagnosis may have an effect on arrest etiology and chance of survival. Previous IHCA survival studies have found that patients on
Received for publication December 6, 2011. Accepted March 30, 2012. Corresponding Author: Dr Blair Carl Schwartz, Jewish General Hospital, Division of General Internal Medicine, 3755 Cote Sainte Catherine, Room G-050, Montreal, Québec H3T 1E2, Canada. Tel.: ⫹1-514-340-8222 ⫻4974; fax: ⫹1-514-340-7905. E-mail: [email protected] See page 121 for disclosure information.
0828-282X/$ – see front matter © 2013 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.cjca.2012.03.024
118
Canadian Journal of Cardiology Volume 29 2013
hospital discharge. Moreover, no patient with an unwitnessed arrest survived to hospital discharge. While these findings require confirmation in a larger study, they merit consideration in the context of code status discussions, particularly with respect to the response to unwitnessed arrests.
l’hôpital. Aucun patient n’a survécu à la sortie après un arrêt non confirmé. Conclusions : L’ACIH des patients à l’UEC en médecine interne est caractérisé par un taux élevé d’AÉSP ou d’asystole, et d’une chance de survie minime à la sortie de l’hôpital. De plus, aucun patient ayant eu un arrêt non confirmé n’a survécu à la sortie de l’hôpital. Bien que ces conclusions doivent être confirmées par une plus vaste étude, elles méritent d’être prises en considération dans le cadre de discussions sur les codes, particulièrement en ce qui concerne la réponse aux arrêts non confirmés.
general wards tended to have lower survival rates than those in monitored settings.11-15 No studies to date have specifically examined the IHCA population of General Internal Medicine patients, who are likely to be older, have more extensive comorbidities, and require admission with a higher case complexity and burden of illness than other ward populations. These patient differences combined with the clinical teaching unit (CTU) milieu, make for a unique population for whom we are unaware of any IHCA survival data. We thus conducted a retrospective cohort study to determine the survival rate after cardiac arrest for patients admitted to 2 Internal Medicine CTUs in a Canadian tertiary centre.
events that met the inclusion criteria, the medical record was abstracted for the predefined patient, resuscitation, and outcome variables using a standardized data collection form. We defined return of spontaneous circulation (ROSC) using the Utstein guideline definition of any palpable central pulse for longer than 20 minutes without chest compressions.16 Patients who achieved ROSC were then further assessed as to whether they survived to be transferred to a critical care area, or survived to be discharged from hospital. Patient demographics and clinical information were obtained from the CTU admission note. Arrest characteristics and outcome data were obtained from the cardiac arrest form completed by the senior Internal Medicine house staff of the resuscitation team. All data abstraction was performed by the primary author (B.C.S.). In the event of uncertainty regarding cardiac arrest classification, this was discussed with a second author (P.J.W.) to obtain consensus. The main outcome of this study was survival to hospital discharge. We also studied the rate of ROSC, and rate of survival to a Critical Care area. Outcomes were analyzed by witnessed vs unwitnessed arrest status. STATA (version 10; Statacorp, College Station, TX) 2 test was performed to evaluate statistical significance of groups when appropriate. The study was approved by the hospital’s Research Ethics Committee.
Methods We performed a retrospective cohort study of all consecutive patients who experienced a cardiac arrest while admitted to an Internal Medicine CTU in a 637 bed tertiary care hospital affiliated with McGill University, Montreal, Canada. The hospital has 2 Internal Medicine CTU wards, with a combined census of 70 patients. In the event of a cardiac arrest or need for urgent medical attention, all personnel are trained to call a “Code Blue,” in response to which an announcement is made overhead and a page is sent to the resuscitation team. This team is fully Advanced Cardiac Life Support trained and staffed by senior Internal Medicine house staff, Critical Care Registered Nurses, and Registered Respiratory Therapists. All Advanced Cardiac Life Support medications, manual defibrillators, and advanced airway equipment were available on each of the 2 CTUs. There was no medical emergency team in the institution. We established our cohort by obtaining a list from the operator of all consecutive Code Blue calls between January 1, 2003 and June 30, 2007 and identified events taking place on the 2 Internal Medicine CTUs. This list was then cross-referenced with the admission and discharge logs of that unit in order to associate a patient with each event. Patients were associated when the death or transfer of a patient corresponded to the date, time, and location of the Code Blue call. When identified, we obtained the complete medical records of the patient and screened the resuscitation event for entry into the cohort. Patients were included if they were admitted to the Internal Medicine service at the time of the event and received chest compressions or electrical cardioversion in response to an absence of signs of circulation. Exclusion criteria included: patients under 20 years of age, events that were exclusively respiratory arrests, the existence of a Do Not Attempt Resuscitation order prior to the event, and resuscitation attempts that were aborted by family or the physician for nonclinical reasons. For
Results Between January 1, 2003 and June 30, 2007 there were 1185 Code Blue calls in the hospital, with 198 (16.7%) on the Internal Medicine CTUs. Details on cohort assembly and demographics are contained in Figure 1 and Table 1, respectively. Our cohort was 65.1% male with a mean age of 75 years (range, 38-97). Infection was the most frequent reason for hospital admission (34.9%), with cancer and cardiovascular causes accounting for similar frequencies of admission at 13.3% and 12% of admissions, respectively. Fifty-three percent of patients had 3 or more comorbid medical conditions at the time admission, including 26.5% with an active malignancy (Table 1). Of the 83 cardiac arrests, 43 (51.8%) were witnessed at the time of the event (Table 2). Pulseless electrical activity (PEA) or asystole was the first rhythm documented by the arrest team in 90.4% of the events. The presenting rhythm did not differ between witnessed and unwitnessed events (P ⫽ 1). While an increased proportion of unwitnessed cardiac arrests was observed between 23:30 and 07:29 compared with other time periods (Table 2), the difference was not statistically significant (P ⫽ 0.157).
Schwartz et al. Internal Medicine Cardiac Arrest Survival
119
CTU Code Blue calls, N = 198 • Cancelled calls, n = 14 (7.1%) • Unidenfied calls, n = 36 (18.2%) • Incomplete medical record, n = 1 (0.5%) Code Blue calls reviewed, n = 147
Cardiac Arrest No resuscitaon aempted n = 22 (15%) • Paent DNAR, n = 19 • Considered fule, n = 3
Cardiac Arrest Aempted resuscitaons n = 83 (56.5%) Presenng rhythm: • VF/VT, n = 8 (9.6%) • Non-VF/VT, n = 75 (90.4%)
Noncardiac Arrest n = 42 (28.6%) • Respiratory arrest, n = 17 • Sepsis, n = 13 • Other (GI bleed, seizure), n = 12
Figure 1. Cohort Utstein-style flow sheet. CTU, Clinical Teaching Unit; DNAR, Do Not Attempt Resuscitation; GI, gastrointestinal; VF/VT, ventricular fibrillation/ventricular tachycardia.
Overall, 34.9% of cardiac arrests achieved ROSC, with 28.9% surviving to be transferred to a critical care area, and 2.4% surviving to hospital discharge. Of the 40 unwitnessed cardiac arrests none survived to hospital discharge.
Table 1. Cohort demographics n (%) Age (y) ⬍ 50 51-60 61-70 71-80 ⬎ 81 Sex Male Admission diagnosis Infection/sepsis Cancer or related Cardiac (MI, CHF, or arrhythmia) Gatrointestinal bleed Renal disease COPD Diabetes Stroke Other Comorbidity Hypertension Diabetes mellitus Coronary artery disease Active malignancy Heart Failure Renal disease COPD Dementia Treated remote malignancy Stroke/TIA Angina pectoris Peripheral arterial disease Valvular heart disease Rheumatic disease Previous cardiac arrest Cardiomyopathy
4 (4.8) 7 (8.4) 15 (18.1) 26 (31.3) 31 (37.3) 54 (65.1) 29 (34.9) 11 (13.3) 10 (12.0) 6 (7.2) 5 (6.0) 4 (4.8) 2 (2.4) 1 (1.2) 15 (18.1) 50 (60.2) 27 (32.5) 23 (27.7) 22 (26.5) 17 (20.5) 17 (20.5) 14 (16.9) 13 (15.7) 11 (13.3) 9 (10.8) 5 (6.0) 5 (6.0) 2 (2.4) 2 (2.4) 1 (1.2) 1 (1.2)
CHF, congestive heart failure; COPD, chronic obstructive pulmonary disease; MI, myocardial infarction; TIA, transient ischemic attack.
Discussion To our knowledge, this study represents the first to address the survival from IHCA of patients admitted to an Internal Medicine CTU. The ROSC rate in our study is comparable with the reported rates from recent cardiac arrest studies (Table 3). However, the rate of survival to hospital discharge in our cohort was lower than has been reported recently. This difference may be explained by factors unique to the general Internal Medicine population and setting. Meaney et al. reported on 51,919 arrests from the National Registry of Cardiopulmonary Resuscitation (NRCPR);7 it should be noted that 48% of their events occurred in an intensive care unit (ICU), 44% of patients were admitted with a cardiac complaint and 79% of their events were characterized as witnessed; this likely explains the differences in the rates of ventricular fibrillation/ventricular tachycardia (VF/VT) and survival to hospital discharge when compared with our cohort. Even when analysis of this registry was restricted to unwitnessed/unmonitored IHCA the rate of survival to hospital discharge (8%) was higher than seen in our cohort.17 Brindley et al. reported on 218 consecutive IHCA events occurring among unmonitored adult in-patients.18 Our Internal Medicine population, however, was considerably older, with 68% of patients older than the age of 70 compared with 46% in Brindley’s study. In addition, the non-Internal Medicine patients in Brindley’s cohort would be expected to have a higher incidence of readily and persistently treatable cardiac arrest etiologies such as postoperative myocardial infarction, hemorrhage, or pulmonary embolism. As well, elective surgery patients have been previously shown to have a higher rate of successful resuscitation after IHCA.19 Our study does, however, confirm Brindley’s and others observation that patients with an unwitnessed cardiac arrest outside of a monitored area did not survive to hospital discharge.14 That the worse outcome after IHCA found in our Internal Medicine population is related to setting, comorbidity, and underlying reason for admission is in keeping with the results of Larkin and colleagues who analyzed the NRCPR cohort for preresuscitation factors associated with mortality.20 They found that
120
Canadian Journal of Cardiology Volume 29 2013
Table 2. Arrest characteristics and outcome Outcome
Total n⫽83 (%) Witnessed n⫽43 (%) Unwitnessed n⫽40 (%)
Initial rhythm
ROSC
ROSC, survived to ICU
ROSC, survived to discharge
VF/VT
29 (34.9) 18 (41.8) 11 (27.5)
24 (28.9) 14 (32.5) 10 (25)
2 (2.4) 2 (4.7) 0 (0)
8 (9.6) 4 (9.3) 4 (10)
Time of day
PEA/ asystole 75 (90.4) 39 (90.6) 36 (90) P ⫽ 1*
07:30-15:29
15:30-23:29
23:30-07:29
29 (34.9) 18 (41.8) 11 (27.5)
27 (32.5) 18 (41.8) 9 (22.5)
27 (32.5) 7 (16.3) 20 (50) P ⫽ 0.157†
ICU, intensive care unit; PEA, pulseless electrical activity; ROSC, return of spontaneous circulation; VF, ventricular fibrillation; VT, ventricular tachycardia. * Comparison of PEA/asystole between witnessed and unwitnessed. † Comparison of events between 23:30 and 07:30 between witnessed and unwitnessed.
advanced age, noncardiac nonsurgical admission, and arrest on a general ward are associated with worse outcome. In particular, pre-existing malignancy, a common condition in Internal Medicine CTU patients and present in 26.5% of our cohort, was associated with a nearly 2-fold increase in the risk of death. To further examine the difference in hospital survival between Internal Medicine and non-Internal Medicine IHCA events we conducted a review of patients admitted to our own institution’s ICU with a diagnosis of IHCA from wards other than the 2 Internal Medicine CTUs. In 2008, 24 such patients were admitted to the ICU with a survival rate to hospital discharge of 29.2%. This would approximate a survival rate from the non-Internal Medicine ward of 8.5% that is on par with previous general ward-based studies and 3.5 times higher than seen in our cohort, further supporting our findings.13,17,18 The frequency of PEA/asystole (90%) in our cohort is higher than has been reported in many studies of IHCA and this distribution was not different between witnessed and unwitnessed events. In part, this may be because, while our cohort had a frequent history of cardiac comorbidities and risk factors, relatively few patients (12%) were admitted with a primary cardiac diagnosis. An IHCA population admitted with pneumonia and similar cardiovascular burden to our cohort reported a 14.7% VF/VT rate and only 4.7% of events attributable to myocardial ischemia.21 It is thus likely that many patients in our cohort arrested as a result of progression of their underlying disease,22 rather than experiencing a sudden cardiac event. These patients are likely to present as PEA/asystole,23 and this would further explain the low rate of survival to hospital discharge. Moreover, processes that lead to PEA/asystole such as hypoxemia and respiratory failure, which are common antecedents of arrest in the Internal Medicine setting,24 are likely to be recognized late in the ward setting. It should be noted that our institution did not have a high dependency unit or a medical emergency team during the study period and this is an important fact in applying our results to clinical practice. While it remains controversial if these elements can reduce the incidence of, or improve survival from cardiac arrest,5,6,17 they are essential in the management of acute noncardiac arrest, life-threatening events, which constituted 28.6% of code
blue calls in our cohort. Thus the risk of harm exists if these patients fail to receive appropriate medical attention due to a Do Not Attempt Resuscitation order. As such our hospital uses a multitiered level of intervention status. We use level 1 and 4 to reflect full supportive measures and palliative therapy respectively. Level 2 patients would have the cardiac arrest team called to provide care as needed, including transfer to the ICU. At this care level patients and providers can set limitations on particular life support options, including their desire for CPR in the case of IHCA. Level 3 patients receive maximal therapy that can be provided on a ward, and are not candidates for transfer to a critical care area. We have found that this system, in conjunction with accurate prognostic information, helps to facilitate these difficult discussions. When deciding about intervention status, patients and their surrogates often receive information about the chance of surviving the event; that the majority of medical CTU patients who are resuscitated from IHCA will die despite admission to a Critical Care area is also relevant to this decision, and to decisions made after “successful” resuscitation. It is likely this knowledge will affect preferences with regard to CPR, post-IHCA management and in turn impact resource utilization. This study is limited by its small cohort size and single centre nature which reduces its generalizability. As well we were unable to identify the patients associated with 19.6% of the Code Blue calls on the 2 CTUs due to the retrospective nature of the study and manner in which cardiac arrest records are maintained. It is highly unlikely that any patient who remained on the ward after a Code Blue call would have met our definition for inclusion in this cohort. A more probable explanation is that these Code Blue calls were due to events other than cardiac arrest, such as syncope or hypoglycemia; such events would not result in death or Critical Care transfer and thus would not be identifiable using our methodology. It is also possible that some Code Blue calls were made for hospital visitors rather than admitted patients, as is the practice in our institution. It is unlikely that a significant number of actual cardiac arrests were missed. It should also be noted that no patients in our cohort were treated with therapeutic hypothermia (TH) post ROSC. TH has been associated with improved outcomes after out of hospital ar-
Table 3. Comparison with other study cohorts
Current Study (2011) Meaney et al. (2010)7 Brindley et al. (2002)18
n
ROSC (%)
Survival to hospital discharge (%)
VF/VT (%)
83 51,919 218
34.9 47.6 29
2.4 17.6 8
9.6 24.1 30
ROSC, return of spontaneous circulation; VF, ventricular fibrillation; VT, ventricular tachycardia.
Schwartz et al. Internal Medicine Cardiac Arrest Survival
121
rests with a shockable rhythm,25 possibly on a neuroprotective basis or due to decreased size of myocardial infarction.26 Improved outcomes however have not been demonstrated with the use of TH in the IHCA population.24,27 This may reflect the different nature of IHCA events or the lack of appropriately powered studies in this unique population. The results of our study would need to be re-evaluated should future studies of IHCA management demonstrate a significant impact on survival. In conclusion cases of IHCA in patients admitted to the Internal Medicine CTU of our hospital represent a unique population in whom we demonstrated a high rate of PEA/asystole and low rate of survival to hospital discharge, possibly on the basis of severe underlying conditions. The absence of survivors to hospital discharge after an unwitnessed arrest in this population should be taken into account when responding to cardiac arrests of this nature and caring for these patients in the Coronary Care Units or ICUs. We would recommend a larger, multi-centre prospective review of IHCA in Internal Medicine in-patients to further establish survival rates for use in code status discussions in this important and unique population.
11. Gwinnutt CL, Columb M, Harris R. Outcome after cardiac arrest in adults in UK hospitals: effect of the 1997 guidelines. Resuscitation 2000; 47:125-35.
Acknowledgements The authors thank Dr Vicky Tagalakis for her critical review of a previous version of this manuscript.
17. Brady WJ, Gurka KK, Mehring B, Peberdy MA, O’Connor RE. In-hospital cardiac arrest: impact of monitoring and witnessed event on patient survival and neurologic status at hospital discharge. Resuscitation 2011; 82:845-52.
Disclosures The authors have no conflicts of interest to disclose.
18. Brindley PG, Markland DM, Mayers I, Kutsogiannis DJ. Predictors of survival following in-hospital adult cardiopulmonary resuscitation. CMAJ 2002;167:343-8.
References
19. Burns R, Graney MJ, Nichols LO. Prediction of in-hospital cardiopulmonary arrest outcome. Arch Intern Med 1989;149:1318-21.
1. Kouwenhoven WB, Jude JR, Knickerbocker GG. Closed-chest cardiac massage. JAMA 1960;173:1064-7. 2. Safar P, Brown TC, Holtey WJ, Wilder RJ. Ventilation and circulation with closed-chest cardiac massage in man. JAMA 1961;176:574-6. 3. Frank C, Heyland DK, Chen B, et al. Determining resuscitation preferences of elderly inpatients: a review of the literature. CMAJ 2003;169: 795-9.
12. Herlitz J, Bang A, Aune S, et al. Characteristics and outcome among patients suffering in-hospital cardiac arrest in monitored and non-monitored areas. Resuscitation 2001;48:125-35. 13. Tunstall-Pedoe H, Bailey L, Chamberlain DA, et al. Survey of 3765 cardiopulmonary resuscitations in British hospitals (the BRESUS Study): methods and overall results. BMJ 1992;304:1347-51. 14. Hershey CO, Fisher L. Why outcome of cardiopulmonary resuscitation in general wards is poor. Lancet 1982;1:31-4. 15. Peatfield RC, Sillett RW, Taylor D, McNicol MW. Survival after cardiac arrest in hospital. Lancet 1977;1:1223-5. 16. Cummins RO, Chamberlain D, Hazinski MF, et al. Recommended guidelines for reviewing, reporting, and conducting research on in-hospital resuscitation: the in-hospital ’Utstein style’. A statement for healthcare professionals from the American Heart Association, the European Resuscitation Council, the Heart and Stroke Foundation of Canada, the Australian Resuscitation Council, and the Resuscitation Councils of Southern Africa. Resuscitation 1997;34:151-83.
20. Larkin GL, Copes WS, Nathanson BH, Kaye W. Pre-resuscitation factors associated with mortality in 49,130 cases of in-hospital cardiac arrest: a report from the National Registry for Cardiopulmonary Resuscitation. Resuscitation 2010;81:302-11.
4. Jones GK, Brewer KL, Garrison HG. Public expectations of survival following cardiopulmonary resuscitation. Acad Emerg Med 2000;7:48-53.
21. Carr GE, Yuen TC, McConville JF, et al. American Heart Association’s Get With the Guidelines-Resuscitation (National Registry of CPR) Investigators. Early cardiac arrest in patients hospitalized with pneumonia: a report from the American Heart Association’s Get With The GuidelinesResuscitation Program. Chest 2012;141:1528-36.
5. DeVita MA, Braithwaite RS, Mahidhara R, et al. Use of medical emergency team responses to reduce hospital cardiopulmonary arrests. Qual Saf Health Care 2004;13:251-4.
22. Yokoyama H, Yonemoto N, Yonezawa K, et al. Report from the Japanese registry of CPR for in-hospital cardiac arrest (J-RCPR). Circ J 2011;75: 815-22.
6. Hillman K, Chen J, Cretikos M, et al. Introduction of the medical emergency team (MET) system: a cluster-randomised controlled trial. Lancet 2005;365:2091-7.
23. Weil MH, Fries M. In-hospital cardiac arrest. Crit Care Med 2005; 33:2825-30.
7. Meaney PA, Nadkarni VM, Kern KB, et al. Rhythms and outcomes of adult in-hospital cardiac arrest. Crit Care Med 2010;38:101-8.
24. Rittenberger JC, Guyette FX, Tisherman SA, et al. Outcomes of a hospital-wide plan to improve care of comatose survivors of cardiac arrest. Resuscitation 2008;79:198-204.
8. Fredriksson M, Aune S, Thoren AB, Herlitz J. In-hospital cardiac arrest–an Utstein style report of seven years experience from the Sahlgrenska University Hospital. Resuscitation 2006;68:351-8.
25. Bernard SA, Gray TW, Buist MD, et al. Treatment of comatose survivors of out-of-hospital cardiac arrest with induced hypothermia. N Engl J Med 2002;346:557-63.
9. Sandroni C, Ferro G, Santangelo S, et al. In-hospital cardiac arrest: survival depends mainly on the effectiveness of the emergency response. Resuscitation 2004;62:291-7.
26. Mottillo S, Sharma K, Eisenberg MJ. Therapeutic hypothermia in acute myocardial infarction: a systematic review. Can J Cardiol 2011;27:555-61.
10. Cooper S, Janghorbani M, Cooper G. A decade of in-hospital resuscitation: outcomes and prediction of survival? Resuscitation 2006;68:231-7.
27. Sandroni C, Nolan J, Cavallaro F, Antonelli M. In-hospital cardiac arrest: incidence, prognosis and possible measures to improve survival. Intensive Care Med 2007;33:237-45.