ORIGINAL ARTICLE
Evaluation of local use of semiautomatic external defibrillators SENDOA BALLESTEROS PEÑA Bilbao SAMUR-Protección Civil, Ayuntamiento de Bilbao, Parque de Bomberos de Miribilla, Bilbao, Bizkaia, Spain. CORRESPONDENCE: Sendoa Ballesteros Peña Bilbao SAMUR-Protección Civil Ayuntamiento de Bilbao Parque de Bomberos de Miribilla C/ Juan Carlos Gortázar 3 48003 Bilbao, Bizkaia, Spain E-mail:
[email protected]
RECEIVED: 8-5-2012
ACCEPTED: 17-6-2012
CONFLICT OF INTEREST: The authors declare no conflict of interest in relation with the present article.
Objective: To evaluate a program to implement use of semiautomatic external defibrillators in a local basic life support unit, including a description of patient characteristics and the main factors leading to events that required out-of-hospital resuscitation maneuvers. Methods: Retrospective study analyzing cases of cardiac arrest in which the first responders were from a local basic life support unit. Cases were those attended during the first 4 years following the unit's acquisition of semiautomatic defibrillators. We recorded epidemiologic variables and early survival after resuscitation; we them assessed associations between failure to resuscitate and risk factors. Results: In 105 cases of cardiac arrest the unit attempted 87 resuscitations; cardiomyopathy was the presumed cause of the arrest in 88.5% of these cases in which resuscitation was attempted. Resuscitation was attempted by a bystander only twice. Ventricular fibrillation was found initially in 14.9% of the patients and was associated with a lower risk of failure (odds ratio, 0.09; 95% CI, 0.02-0.23). In 10.3% of the events, the patient was transported to a hospital after circulation had returned. Conclusions: The basic life support unit's rate of successful cardiopulmonary resuscitation is similar to that of advanced life support services in the same local community. These success rates are low, however. Survival was higher in patients who had ventricular fibrillation on initiation of resuscitation. [Emergencias 2013;25:273-277] Keywords: Heart arrest. Cardiopulmonary resuscitation. Emergency health services. Ventricular fibrillation.
Introduction Defibrillation is a key link in the survival chain; it is one of the few operations that has irrefutably shown improved results of cardiopulmonary resuscitation (CPR) after sudden cardiac arrest (SCA) with ventricular tachyarrhythmia. However, the probability of defibrillation success and subsequent survival to hospital admission decreases rapidly with time, so early defibrillation is essential. The use of portable automated external defibrillators (AEDs) has resulted in improved effective response time by providing first responders (not necessarily medically trained) with guidance on the application of electrical therapy for out-of-hospital SCA, even before the arrival of medical professionals1. Public access defibrillation programs and equipping first medical responders with AEDs may increase CPR and early defibrillation and therefore improve survival rates2,3. The aim of this study was to evaluate the reEmergencias 2013; 25: 273-277
sults obtained after implementation of an AED program in a basic life support (BLS) unit and detail the epidemiological characteristics of patients assisted and the major factors involved in the outcome after out-of-hospital CPR.
Method We performed a retrospective observational study including all patients diagnosed with SCA of any etiology, considered for CPR and treated by non-physician responders in a local Bizkaia BLS service, after AED implementation (1 January 2006) until December 31, 2010. The working area was limited to that of an ambulance included in the Emergency 112 network, under collaborative agreement with the system of public health emergencies of the Basque Autonomous Community (Emergentziak Osakidetza). This unit is assigned to cover a geographical area as the second ambulance response for neigh273
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boring municipalities. The area covered was approximately 6.7 km2 (over 50 km2 if one includes municipalities for which this was the second ambulance) and the population served consisted of more than 77,000 inhabitants (expandable to 235,000 in the above situation), of whom 20% are aged over 65 years. Mean annual emergencies attended was around 3,700 at the time of the present study. The ambulance is staffed by at least two professionals or volunteers trained in BLS, AED use and emergency techniques, with training regulated according to regional legislation4,5. Resuscitation, respecting the criteria for not initiating resuscitation (NIR), was performed according to current European Resuscitation Council guidelines6. However, all NIR situations were monitored by phone by the emergency coordination center. For each patient we recorded information on age and sex, geographical area and time and place of the event (home or public area), time elapsed from ambulance alert by the coordinating center to start of BLS maneuvers and from the latter to arrival of the advanced life support (ALS) unit, probable etiology of SCA, presence of witnesses and/or bystander rescuers before BLS arrival, initial electrocardiographic rhythms registered by the AED and immediate outcome of resuscitation (death or recovery of spontaneous circulation-ROSC). The results of the categorical variables are expressed as absolute frequencies and percentages. Quantitative variables are described as median (Me) and interquartile range (IQR). For hypothesis testing we used chi-square or Fisher exact test and the parametric Mann Whitney U test, respectively, for a two-sided significance level of 95%. The magnitude of the association was assessed by crude calculation of the odds ratio (OR) and 95% confidence intervals (95% CI) the failure of CPR according to the different variables of exposure. Data analysis was performed using the PASW 17 and Epiinfo 3.5.1 software packages.
Results In a total of 105 alerts of possible SCA (Figure 1), CPR was initiated in 87 patients (82.9%); etiology was presumably cardiac in 77, trauma in 3, and the rest were secondary to: asphyxia (1), drug overdose (1), cerebrovascular disease (2) and other (non-cardiac) unspecified diseases (5). In the remaining 18 alerts (17.1%), CPR was not indicated according to protocol. 274
Of the 87 patients undergoing CPR, 56.3% were men, with median age of 72 years (IQR 54.25 to 81.75). Median age of the women treated was 80 years (IQR: 72.25 to 85.5), with no significant age differences between men and women (p = 0.26). The outcome of 75 attempts at resuscitation (86.2%) was death. Were transferred into ten patients (11.5%) were transferred to the emergency department (ED ) after ROSC; 7 were men, with a median age of 59 years (IQR = 40-81) and 3 were women, with a median age of 48 years (IQR = 41-66.5). Two other people were admitted to the ED with cardiac arrest. Of the resuscitated patients taken to hospital, their evolution, survival and sequelae at discharge are unknown. The median time from ambulance alert to the start of BLS maneuvers was 8 minutes (IQR = 612), and from the beginning of the BLS maneuvers to ALS unit arrival, median time was 10 minutes (IQR = 7-15). No significant differences were found in either of these parameters (p = 0.68 and 0.1, respectively). Before arrival on the scene of the first resource, CPR was only initiated twice, by a passing doctor and a policeman. The study of possible factors associated with resuscitation failure (Table 1) showed that only a shockable initial rhythm was significantly associated with less CPR failure (OR 0.09, 95% CI 0.02 to 0.53).
Discussion The proportion of patients with ROSC after CPR in the out-of-hospital setting is very similar to that reported in earlier studies carried out by advanced life support services in the same community7. These figures are also comparable to those achieved in Galicia 8 after implantation of the "AEDs Plan" (11.3%), but considerably lower than those provided by the BLS unit of the city of Madrid9 (45.5%) and by the ALS unit of the same service. Survival rates for out-of-hospital SCA commonly range from 6 to 45%10,11, sometimes explicable in terms of geographic area coverage (urban vs suburban/rural). Patients with shockable ECG rhythm (VF / PVT) presented a higher survival rate, as reported elsewhere1. Only this variable showed a significant association with ROSC after CPR. The number of victims with initial VF (13 cases, 15% of cases in which CPR was started) was notably low compared with reports in the literature which are rarely less than 25%12,13. Emergencias 2013; 25: 273-277
EVALUATION OF LOCAL USE OF SEMIAUTOMATIC EXTERNAL DEFIBRILLATORS
Confirmed SCA patients considered for CPR n = 105
CPR not attempted (NIR) n = 18
CPR attempted n = 87
Non-cardiac etiology n = 10
Cardiac etiology n = 77
SCA not witnessed n = 12
Initial rhythm Asystole n = 49
PCR witnessed (by EMS) n=3
SCA witnessed n = 17
Initial rhythm FV n = 13
No return of spontaneous circulation n = 75
Other initial nonshockable rhythms n = 16
Initial rhythm PVT n=0
Bystander CPR n=2
? n = 55
Rhythm ? non-shockable n=9
No bystander CPR n = 85
Return of spontaneous circulation n = 10*
? n = 2**
Figure 1. Utstein register of cardiac arrests attended by the basic life support unit during the years 2006-2010. SCA: sudden cardiac arrest, CPR: cardiopulmonary resuscitation, VF: ventricular fibrillation; PVT: pulseless ventricular tachycardia; ?: Unknown. NIR: not initiating CPR. *All patients were admitted to the hospital emergency room in this state. **Patients with SCA admitted to the hospital emergency department.
The variable most closely associated with CPR failure was time to first BLS maneuvers of 8 minutes or higher (OR 3.38, p = 0.10). However, unlike previous study results14, this association was not statistically significant. This may be partly due to the low number of patients resuscitated, homogeneity of overall response intervals or because CPR was initiated in patients unlikely to benefit from resuscitation attempts, in the absence of a Emergencias 2013; 25: 273-277
protocol to determine the appropriateness of resuscitation which is pending the final decision of the coordination center. The overall response intervals of the first resource were higher than those proposed by some European standards15 (less than 8 minutes in 75% of life-threatening situations). The fact that a third of the interventions took place outside the assigned area of operation negatively influenced the 275
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Table 1. Main patient characteristics and analysis of the association between out-of-hospital resuscitation failure and associated factors Total cases registered n
Deaths n (%)
ROSC n (%)
OR (95% CI)
P
Sex Women 37 34 (91.9) 3 (8.1) 1.93 (0.40-10.34) 0.50 Men 48 41 (85.4) 7 (14.6) Age > 80 years 29 25 (89.3) 3 (10.7) 1.06 (0.21-5.94) > 0.93 ⱕ 80 years 54 47 (88.7) 6 (11.3) Presumed etiology of CA Non-cardiac 10 9 (90) 1 (10) 1.22 (0.17-30.00) > 0.85 Cardiac 77 66 (88) 9 (12) Place of the event Home 68 62 (91.2) 6 (8.8) 3.18 (0.64-15.52) 0.10 Public space 19 13 (76.5) 4 (23.5) Area of action Outside area 28 24 (85.7) 4 (14.3) 0.71 (0.16-3.09) > 0.61 Within area 59 51 (89.5) 6 (10.5) Alert - BLS interval 8 (6-12) 5.5 (3-10) ⱖ 8 minutes 45 42 (93.3) 3 (6.7) 3.33 (0.70-21.60) 0.16 < 8 minutes 38 29 (80.6) 7 (19.4) BLS - ALS interval 10 (7-15) 7 (3-10) ⱖ 8 minutes 44 41 (93.2) 3 (6.8) 4.70 (0.88-32.41) 0.07 < 8 minutes 25 17 (73.9) 6 (26.1) Witnessed CA No 12 10 (83.3) 2 (16.7) 1.43 (0.17-14.17) > 0.71 Yes 20 14 (77.8) 4 (22.2) Initial rhythm Shockable 13 7 (58.3) 5 (41.7) 0.09 (0.02-0.53) 0.003 Non-shockable 65 60 (93.7) 4 (6.3) IQR: interquartile range; ROSC: spontaneous return of circulation; OR: Odds Ratio; CI: confidence interval; BLS: basic life support; ALS: advanced life support; CA: cardiac arrest; VF: ventricular fibrillation. In some groups the sum may not equal the total value due to missing values or uncertainty about the final outcome after resuscitation (patients admitted to hospital).
achievement of this target. Reducing SCA response time is a priority given its key role in the outcome of resuscitation. There was no statistically significant association between outcome and place of SCA event (home vs. public space). One would expect that public space SCA increases bystander or even CPRtrained witness involvement which should favor better CPR results1,2. The European Resuscitation Council6 considers it essential to train members of the general public in CPR and AED use, and clearly recommends equipping BLS units with AEDs. All Basque BLS units currently have personnel trained and equipped to perform quality out-of-hospital CPR, but the general population present important shortcomings with respect to identifying SCA and how to act in response, which is the first link in the chain of survival. The data still reflect a fateful reality: 98% of the patients attended did not receive any CPR before the arrival of the first healthcare resource. This figure is very much higher than that reported in other national studies, which range from 18%8 to 36.8%13. This situation indicates the need for effective strategies on training target populations in basic resuscitation and AED use15. 276
References 1 Koster RW, Baubin MA, Bossaert LL, Caballero A, Cassan P, Castrén M, et al. European Resuscitation Council Guidelines for Resuscitation 2010. Section 2. Adult basic life support and use of automated external defibrillators. Resuscitation. 2010;81:1277-92. 2 Weisfeldt ML, Sitlani CM, Ornato JP, Rea T, Aufoderheide TP, Davis D, et al. Survival after application of automatic external defibrillators before arrival of the emergency medical system: evaluation in the resuscitation outcomes consortium population of 21 million. J Am Coll Cardiol. 2010;55:1713-20. 3 The Public Access Defibrillation Trial Investigators. Public-access defibrillation and survival after out-of-hospital cardiac arrest. N Engl J Med. 2004;351:637-46. 4 Decreto 16/2005, de 25 de enero, por el que se regula el uso de desfibriladores externos automáticos por personal no médico. Boletín Oficial del País Vasco; 27: 1693-1697. (Consultado 20 Febrero 2012). Disponible en: http://www.euskadi.net/cgi-bin_k54/bopv_20?c&f=20050209&a=200500561 5 Decreto 8/2007, de 23 de enero, sobre el uso de desfibriladores externos automáticos por personal no sanitario. Boletín Oficial del País Vasco; 30: 2856-2864. (Consultado 20 Febrero 2012). Disponible en: http://www.euskadi.net/cgi-bin_k54/bopv_20?c&f=20070212&a=200700896 6 Consejo Español de Resucitación Cardiopulmonar. Recomendaciones en Resucitación Cardiopulmonar del European Resuscitation Council. Traducción Oficial Autorizada. 2005. (Consultado 13 Febrero 2012). Disponible en: http://www.seslap.com/seslap/html/fcontinuada/pdf/nr_rcp.pdf 7 Uriarte Itzazelaia E, Alonso Moreno D, Odriozola Aranzábal G, Royo Gutiérrez I, Chocarro Aguirre I, Alonso Jiménez-Bretón J. Supervivencia de la parada cardiorrespiratoria extrahospitalaria en Gipuzkoa: cuatro años de seguimiento. Emergencias. 2001;13:381-6. 8 Iglesias Vázquez JA, Rodríguez Núñez A, Barreiro Díaz MV, Sánchez Santos L, Cegarra García M, Penas Penas M. Plan de desfibrilación externa semiautomática en Galicia. Resultados finales de su implantación. Emergencias. 2009;21:99-104. 9 Moreno Martín JL, Esquilas Sánchez O, Corral Torres E, Suárez Bustamante RM, Vargas Román MI. Efectividad de la implementación de la desfibrilación semiautomática en las Unidades de Soporte Vital Básico. Emergencias. 2009;21:12-6. 10 Nolan JP, Jasmeet Soarb DA, Zidemanc DB, Bossaerte LL, Deakinf RC, Kosterg W. European Resuscitation Council Guidelines for Resuscita-
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tion 2010 Section 1. Executive summary. Resuscitation. 2010;81:1219-76. 11 Lui JCZ. Evaluation of the use of automatic external defibrillation in outof-hospital cardiac arrest in Hong Kong. Resuscitation. 1999;41:113-9. 12 Rea TD, Pearce RM, Raghunathan TE, Lemaitre RN, Sottodehnia N, Jouven X, et al. Incidence of out-of-hospital cardiac arrest. Am J Cardiol. 2004;93:1455-60. 13 Navalpotro Pascual JM, Fernández Pérez C, Navalpotro Pascual S. Supervivencia en las paradas cardiorrespiratorias en las que se realizó reanimación cardiopulmonar durante la asistencia extrahospitalaria. Emergencias. 2007;19:300-5.
14 Moreno Martín JL, Esquilas Sánchez O, Corral Torres E, Suárez Bustamante RM, Vargas Román MI. Efectividad de la implementación de la desfibrilación semiautomática en las Unidades de Soporte Vital Básico. Emergencias. 2009;21:12-6. 15 Unanue JM, Pérez I, Alcorta I, Gurruchaga MI, Lasa MM, ArreseIgor A, et al. Estudio de las prestaciones sanitarias urgentes y emergentes en la Comunidad Autónoma Vasca: análisis y propuestas de mejora. Investigación Comisionada. Vitoria-Gasteiz: Departamento de Sanidad y Consumo. Gobierno Vasco; 2009. Informe n.o: Osteba D-09-05.
Evaluación de un programa local de desfibrilación externa semiautomática Ballesteros Peña S Objetivos: Conocer los resultados tras la implementación de un programa de desfibrilación externa semiautomática (DESA) en una unidad local de soporte vital básico (USVB), y detallar el perfil epidemiológico de los pacientes asistidos y los principales factores implicados en el desenlace tras las maniobras de reanimación extrahospitalaria. Método: Estudio retrospectivo que analizó las asistencias por parada cardiorrespiratoria (PCR) atendidas por una USVB local como primer recurso en la escena, desde la implementación de DESA y hasta 4 años después. Se registraron las características epidemiológicas básicas y la supervivencia inmediata tras la reanimación. Se investigó la asociación entre el fracaso de la reanimación y los diferentes factores de exposición. Resultados: De 105 eventos por PCR se realizaron 87 intentos de reanimación, de los que el 88,5% fueron de etiología cardiaca. Tan sólo en 2 ocasiones se practicó reanimación por parte de testigos circunstanciales. El 14,9% de los sujetos presentaron fibrilación ventricular (FV) como ritmo electrocardiográfico inicial. La FV se asoció a una menor probabilidad de fracaso tras reanimación (OR 0,09; IC95% 0,02-0,23). El 10,3% de los pacientes fueron transferidos al hospital tras el retorno de la circulación. Conclusiones: La proporción de pacientes reanimados tras una PCR es similar a la obtenida en los servicios de soporte vital avanzado dentro de la misma comunidad. Sin embargo, las tasas de recuperación continúan siendo bajas. Se encontró una mayor supervivencia en pacientes que presentaron FV como ritmo inicial. [Emergencias 2013;25:273-277] Palabras clave: Paro cardiaco. Resucitación cardiopulmonar. Servicios médicos de urgencia. Fibrilación ventricular.
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