Citation for published version (APA): Zijlstra, J. A. (2018). The contribution of lay rescuers in out-of-hospital cardiac arrest

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1 UvADARE (Digital Academic Repository) The contribution of lay rescuers in outofhospital cardiac arrest Zijlstra, J.A. Link to publication Citation for published version (APA): Zijlstra, J. A. (2018). The contribution of lay rescuers in outofhospital cardiac arrest General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: or a letter to: Library of the University of Amsterdam, Secretariat, Singel 25, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. UvADARE is a service provided by the library of the University of Amsterdam ( Download date: 20 Nov 2018

2 CHAPTER Psychological impact on dispatched local lay rescuers performing bystander cardiopulmonary resuscitation J.A. Zijlstra, S.G. Beesems, R.J. de Haan, R.W. Koster Resuscitation 2015;92:

3 60 Chapter ABSTRACT Aim: We studied the shortterm psychological impact and posttraumatic stress disorder (PTSD)related symptoms in lay rescuers performing cardiopulmonary resuscitation (CPR) after a text message (TM)alert for outofhospitalcardiac arrest, and assessed which factors contribute to a higher level of PTSDrelated symptoms. Methods: The lay rescuers received a TMalert and simultaneously an with a link to an online questionnaire. We analyzed all questionnaires from February 2013 until October 201 measuring the shortterm psychological impact. We interviewed by telephone all first arriving lay rescuers performing bystander CPR and assessed PTSDrelated symptoms with the Impact of Event Scale (IES) 6 weeks after the resuscitation. IESscores 0 8 reflected no stress, 9 25 mild, 26 3 moderate, and 75 severe stress. A score 26 indicated PTSD symptomatology. Results: Of all alerted lay rescuers, 6572 completed the online questionnaire. Of these, 1955 responded to the alert and 507 assisted in the resuscitation. We interviewed 203 first arriving rescuers of whom 189 completed the IES. Of these, 1% perceived no/mild shortterm impact, 6% bearable impact and 13% severe impact. On the IES, 81% scored no stress and 19% scored mild stress. None scored moderate or severe stress. Using a multivariable logistic regression model we identified three factors with an independent impact on mild stress level: no automated external defibrillator connected by the lay rescuer, severe shortterm impact, and no (very) positive experience. Conclusion: Lay rescuers alerted by text messages, do not show PTSDrelated symptoms 6 weeks after performing bystander CPR, even if they perceive severe shortterm psychological impact.

4 Psychological impact of lay rescuers performing CPR 61.1 INTRODUCTION To achieve earlier cardiopulmonary resuscitation (CPR) and defibrillation, first responder and public access defibrillation programs are widely introduced. In addition, in the last years strategies to involve local lay rescuers close to the site of a cardiac arrest, with or without guidance to an automated external defibrillator (AED), are implemented. 1 In two Dutch regions, local lay rescuers have contributed to early defibrillation. Their participation in the cardiac arrest system is thus substantial. Resuscitation attempts are stressful events and may lead to severe stress including posttraumatic stress disorder (PTSD), even in (volunteer) emergency personnel/technicians. 5,6 A few studies investigated bystanders psychological reactions and experiences, 7,8 while one qualitative study of first responders who attempted resuscitation of outofhospital cardiac arrest (OHCA) victims, investigated their psychological profile and factors that might protect them against negative psychological reactions. 9 In contrast to professional rescuers, lay rescuers may only rarely be involved in resuscitation. However, their contribution to the resuscitation becomes more extensive since they do not only perform CPR but also may connect an AED and defibrillate. For the continuity of the Dutch text message (TM)alert system and potential expansion to other regions, it is important to evaluate whether lay rescuers are able to cope with the impact and stress that originates from resuscitating a cardiac arrest patient. The aims of this study were therefore (a) to assess the perceived shortterm impact on psychological wellbeing of lay rescuers performing bystander CPR and the level of PTSDrelated symptoms 6 weeks after the resuscitation, and (b) to investigate which factors may contribute to PTSD symptomatology in these lay rescuers..2 METHODS Settings In the Netherlands, when a cardiac arrest is suspected, the emergency medical service (EMS) dispatcher sends two ambulances from a single tier ambulance agency equipped with a defibrillator, first responders (e.g. police officers) with an AED and recently if available, lay rescuers with and without directions to an AED. These lay rescuers followed a standard European Resuscitation Council (ERC) CPR/AED course but are not required to have medical expertise. Police officers or fire fighters can serve as volunteers in this system, but are never part of EMS and only followed a standard lay rescuer CPR/AED course. The dispatcher sends text messages (TMalert) to a maximum of 30 lay rescuers within a 1000m radius around the cardiac arrest patient. The text messages can direct the rescuer to the cardiac arrest site directly, or to a nearby AED first.

5 62 Chapter The current study is part of the AmsteRdam REsuscitation STudies (ARREST), an ongoing prospective registry of all OHCAs in the Dutch province of NorthHolland, which since 2010 also includes the eastern region Twente. Details of the data collection in the ARREST study are described elsewhere. 10 Study design The two regions involved in this study are NorthHolland North and Twente. These regions have a comparable number of inhabitants: and , respectively. We performed a prospective observational study in the period from February 2013 until October 201. On October 31 st 201, a total of 785 and 958 AEDs, and 5735 and lay rescuers were registered in the TMalert system in NorthHolland North and Twente, respectively. The study involved three phases of contact with the lay rescuers. An overview of these phases with their aims is shown in Figure.1. Activation of TMalert system by dispatcher: text messages to lay rescuers 3 days 6 weeks Phase 1: Simultaneously with text messages an with link to online questionnaire Aim: How many lay rescuers respond to alert/arrive on scene/participate in resuscitation Assess level of perceived shortterm psychological impact Identify first arriving lay rescuers who provide CPR and/or use AED Phase 2: Semistructured interview by telephone with first arriving lay rescuers who provide CPR and/or use AED Aim: Obtain detailed information about the resuscitation and the lay rescuers Phase 3: Send Impact of Event Scale to all interviewed lay rescuers Aim: Measure IESstress level (level of PTSDrelated symptoms) Figure.1 Timeline including the three phases of the study with their corresponding aims. AED indicates automatic external defibrillator; CPR, cardiopulmonary resuscitation; IES, Impact of Event Scale; PTSD, posttraumatic stress disorder; and TM, text message.

6 Psychological impact of lay rescuers performing CPR 63 Phase 1: Online questionnaire With each TMalert an was sent to all alerted lay rescuers with a link to an online questionnaire. This questionnaire included questions about the lay rescuers (sex and mobile phone number), their response to the alert, reasons for not responding, mode of transport used, order of arriving, if they provided assistance and what kind of assistance, their perceived shortterm psychological impact (no/mild, bearable or severe) and their perceived level of preparedness to their tasks. Inclusion of interviewees Based on all submitted questionnaires we invited all first arriving lay rescuers who provided bystander CPR and/or connected an AED prior to EMS arrival to participate in a semistructured interview by telephone. If the first arriving lay rescuer did not fill out the questionnaire the second, third, fourth or fifth lay rescuer was contacted. We aimed to interview the rescuers within a few days after receiving the completed online questionnaires. Phase 2: Semistructured interview by telephone Most interview questions were chosen based on previous literature 7,8,11 and we added the following item: if the lay rescuer performed CPR previously. All questions that were answered with the online questionnaire were verified during the interview. The interview always began with the following question: Can you describe what happened after receiving the TMalert?. Second, if not already mentioned, the lay rescuers were asked if they knew the patient, if they encountered problems or difficulties while resuscitating and if they had talked to other people about their experience. Furthermore, they were asked if the patient was transported to the hospital and if they had performed CPR previously. To have a better understanding of the lay rescuers perceived psychological impact, all lay rescuers were asked to explain the burden of the resuscitation. Additionally, they were asked if they feel sufficiently prepared to resuscitate again and how they would rate their resuscitation experience. At the end of the interview, more detailed questions about the lay rescuers were asked (age, profession and highest education). All interviews were performed by the first author (JAZ) and took approximately 25 minutes each. Phase 3: Impact of Event Scale The Impact of Event Scale (IES) was used to measure psychological symptoms of PTSD (Supplemental Figure.1). 12 The Dutch IES is a validated instrument to assess the psychological impact of a variety of traumas and can be used as a selfreport inventory. The first dimension is intrusion (intrusively experienced ideas, images, feelings, or bad dreams) and the second dimension is avoidance (selfreported avoidance of certain ideas, feelings, or situations). 13 The scale provides a total subjective stress

7 6 Chapter score. The following cutoff levels of subjective stress scores were employed: 0 8 (none), 9 25 (mild), 26 3 (moderate), and 75 (severe). 1 A score of 26 indicates a clinical significant stress reaction, warranting further evaluation. The IES measures PTSD symptomatology and is not a substitute for an actual clinical diagnosis of PTSD. 15 We sent the IES by to all interviewed lay rescuers four weeks after the resuscitation and spoke to the respondents again to discuss their answers by telephone. Additionally, we asked if they knew whether the patient was discharged alive from the hospital. If the lay rescuers did not respond to this , we sent a maximum of two reminder s (five and six weeks after the resuscitation). Statistical analysis Continuous variables were described as means and standard deviations (SD) and categorical variables as percentages. We used the Student s ttest to compare differences in mean age, and we analyzed differences between proportions with the Chisquare statistic. The impact of prognostic factors (in terms of patient and lay rescuer characteristics, resuscitation aspects, patient outcomes and impactrelated characteristics) on patient s IESstress level was analyzed using univariable logistic regression analysis. Variables with a P 0.2 were additionally included in a multivariable regression model to determine their independent impact on stress level. Effect sizes were expressed in odds ratios (OR). Statistical uncertainty was expressed in 95% confidence intervals (CI). Calibration (HosmerLemeshow statistic) and discrimination (area under the curve [AUC]) were used to assess the predictive performance of the model. All statistical tests were twotailed and P<0.05 was considered to indicate statistical significance. All statistical analyses were performed in SPSS version RESULTS Online questionnaire and study population In the study period, the dispatcher activated the TMalert system 977 times, sending text messages to a total of lay rescuers; on average to 27 lay rescuers per TMalert. A total of 6572 (25%) lay rescuers completed the questionnaire median (Q1 Q3) seven hours (1 23 hours) after the EMS call (Figure.2). A total of 226 (3%) lay rescuers had responded to the alert. Most important reasons for not responding were: not in close vicinity or not noticing the TMalert. Of the 1955 (30%) TMresponders who arrived on scene, 1065 (5%) went by car, 535 (27%) by bike and 299 (15%) by foot. Of all arriving lay rescuers, 507 (26%) provided assistance in a resuscitation. These 507 lay rescuers were involved in 293 of total 977 (30%) TMalert system activations.

8 Psychological impact of lay rescuers performing CPR 65 Mode of transport: 1065 By car 535 By bike 299 By foot 52 Other Unknown Completed online questionnaires n=6572 Responded to TMalert n=226 Arrived on scene n= Did not respond to TMalert 291 Discontinued journey* 523 No cardiac arrest on arrival 925 Did not assist in resuscitation Reason no response: 2067 Not in close vicinity 122 Not noticing alert 516 No opportunity 217 Not receiving alert 169 Already hearing siren 105 Physically unable 10 Other 18 Unknown Assisted in resuscitation n=507 (293 events) Invited for interview n=229 Interviewed and eligible for analysis n= Did not provide CPR/use an AED or was not the first TMresponder to arrive 13 Did not respond to invitation 3 Did not want to participate 2 Did not have time 8 Interviewed more than once 1 Did not complete IES Completed IES n=189 Figure.2 Lay rescuer inclusion flowchart. AED indicates automatic external defibrillator; CPR, cardiopulmonary resuscitation; IES, Impact of Event Scale; and TM, text message. * Reasons for discontinuation are: hearing ambulance/police siren, not finding the address mentioned in the text message. These lay rescuers assisted in the resuscitation by taking care of bystanders and/or assisting other rescuers. Of all assisting lay rescuers, 229 (5%) were invited to participate in a semistructured interview by telephone. Lay rescuers who were not invited a) did not provide CPR and/or did not use an AED, or b) were not the first lay rescuer to arrive. Two hundred three (89%) were interviewed and eligible for analysis. In total, 189 (93%) lay rescuers also completed the IES. Characteristics of interviewed lay rescuers Table.1 shows the characteristics of the cardiac arrest patients and of the lay rescuers who completed the IES. Median (Q1 Q3) time interval between the resuscitation and interview was three days (1 5). Although most lay rescuers received a TMalert to go to an address in their own neighborhood, 121 (6%) did not know/recognize the patient. Twentyone of the 189 (11%) lay rescuers were involved in a resuscitation that was not continued by EMS. In 1 (7%) cases the lay rescuers provided CPR and/

9 66 Chapter Table.1 Lay rescuer and patient characteristics Lay rescuer related characteristics, n (%) unless otherwise stated n=189 Mean age (SD) years* 6 (12) Male 12 (66) Profession* Lay rescuer Offduty professional rescuer Highest level of education* University degree (graduate degree) Higher education (college) High school diploma Relationship with patient* Unknown to lay rescuer Known to lay rescuer 109 (58) 80 (2) 75 (0) 83 () 31 (16) 121 (6) 68 (36) Did perform CPR previously* 108 (57) Patient characteristics, n (%) unless otherwise stated n=189 Mean age (SD), years 66 (16) Male 126 (67) Resuscitation continued by EMS Resuscitation discontinued by EMS Signs of prolonged death No cardiac arrest Do not resuscitate order found Wish of family Patient outcome Died on scene Transported to hospital 168 (89) 21 (11) 1 (7) (2) 2 (1) 1 (1) 101 (53) 88 (7) CPR indicates cardiopulmonary resuscitation; and EMS, emergency medical services. * Answer to this question obtained through semistructured interview by telephone that was performed median three days after the resuscitation. Answer to this question obtained through the online questionnaire that was send to all lay rescuers simultaneously with the text message alert. Rescuer such as fire fighter, police officer and health care professional. Variable obtained from ARREST database. or connected an AED on a victim who, according to EMS, showed signs of prolonged death and in four (2%) cases the lay rescuer believed the patient had a true cardiac arrest, but EMS identified rhythm and output. Apart from a difference in the mean age of the lay rescuers (6 and 37 years; P<0.01), there were no other significant differences in characteristics between the 189 lay rescuers who completed the IES and the 1 who did not complete the IES. Shortterm impact compared to Impact of Event Scale The interviewed lay rescuers completed the online questionnaire measuring the shortterm impact, median (Q1 Q3) five hours (1 19 hours) after receiving the TM

10 Psychological impact of lay rescuers performing CPR 67 Perceived shortterm psychological impact n=189 IES score 6 weeks after resuscitation n=189 No/mild impact n= IES 0 8, none n=153 Bearable impact n=87 Severe impact n= IES 9 25, mild n=36 IES 26 3, moderate n=0 IES 75, severe n=0 Figure.3 Comparison of perceived shortterm psychological impact and the level of posttraumatic stress disorder related symptoms on the Impact of Event Scale 6 weeks after the resuscitation. IES indicates Impact of Event Scale. alert. The time interval between the TMalert and IES completion was minimally 28 days, median (Q1 Q3) 32 days (29 38). Figure.3 shows the perceived shortterm psychological impact in relation to the IESstress level 6 weeks after the resuscitation. Of the 189 interviewed lay rescuers who also completed the IES, 78 (1%) reported no/mild shortterm psychological impact, 87 (6%) bearable impact and 2 (13%) severe impact. On the IES, 153 (81%) scored 0 8 (no stress) and 36 (19%) scored 9 25 (mild stress). No lay rescuers scored 26 (moderate or severe stress). No lay rescuers with bearable or severe psychological impact on the short term, had more than a mild stress level on the IES 6 weeks after the resuscitation. Of all lay rescuers, 186 (98%) stated that they would definitely resuscitate again; only three (2%) had some doubts. Two of them perceived bearable shortterm psychological impact and one perceived severe impact. All three had a stress score between 0 and 8.

11 68 Chapter Table.2 Univariable associations of lay rescuer and patient related characteristics with the Impact of Event Scale score None (0 8) n=153 Mild (9 25) n=36 OR (95%CI) Pvalue Lay rescuer related characteristics, n (%) Sex* Female Male 5 (83) 99 (80) 11 (17) 25 (20) 1.2 ( ) 0.59 Mean age in years <6 years 6 years 81 (86) 72 (76) 13 (1) 23 (2) 2.0 (0.9.2) 0.07 Profession Offduty professional rescuer Lay rescuer 69 (86) 8 (77) 11 (1) 25 (23) 1.9 (0.9.1) 0.12 Highest level of education University degree (graduate degree) Higher education (college) High school diploma 60 (80) 66 (80) 27 (87) 15 (20) 17 (21) (13) 1.0 ( ) 0.6 ( ) Relationship with patient Unknown to lay rescuer Known to lay rescuer Patient related characteristics, n (%) Sex Female Male 103 (85) 50 (7) 53 (8) 100 (79) 18 (15) 18 (27) 10 (16) 26 (21) 2.1 (1.0.3) 1. ( ) Age in years <0 68 (8) 79 (81) 6 (55) 13 (16) 18 (19) 5 (6) 1.2 ( ). ( ) * Answer to this question obtained through the online questionnaire that was send to all lay rescuers simultaneously with the text message alert. Answer to this question obtained through semistructured interview by telephone that was performed median three days after the resuscitation. Variable obtained from ARREST database. Univariable analysis of factors associated with mild stress Through the online questionnaire and the interview by telephone we assessed univariable associations with mild stress within two domains: lay rescuer and patient related characteristics (Table.2) and factors related to resuscitation, outcome and impact (Table.3). One lay rescuer related characteristic, relationship with patient (OR 2.1, 95% CI 1.0.3, P=0.05) tended towards an association with a mild stress level. Patient s age (<0 years) was associated with mild stress (OR., 95% CI , P=0.03). Two resuscitation aspects were associated with mild stress: lay rescuer not connecting an AED (OR 3.8, 95% CI , P=0.02) and lay rescuer not performing CPR previously (OR 2.5, 95% CI , P=0.02). None of the outcome related factors were associated with level

12 Psychological impact of lay rescuers performing CPR 69 of stress. Two impact related factors were associated with mild stress: perceiving severe shortterm psychological impact compared to no/mild shortterm impact (OR.6, 95% CI , P<0.01) and rating their resuscitation experience not positive compared to rating their experience (very) positive (OR 3.5, 95% CI , P=0.02). After the resuscitation, 176 (93%) lay rescuers talked with their family member(s), friend(s) or colleague(s) and 19 (10%) (also) talked to a professional (e.g. first aid instructor or general practitioner). Only 6 (3%) lay rescuers did not feel the need to talk to someone about their experience. Multivariable analysis of factors independently associated with mild stress The following variables were included in the model: lay rescuers age, lay rescuers profession, lay rescuers relationship with the patient, patients age, AED connected by lay rescuer, lay rescuer performing CPR previously, lay rescuers perceived shortterm psychological impact, and how the lay rescuers rate their resuscitation experience. We found three significant variables that were independently associated with the outcome mild stress : no AED connected by lay rescuer (OR., 95% CI , P=0.01), lay rescuers who perceived severe shortterm psychological impact (OR 5.8, 95% CI , P<0.01) and lay rescuers rating their experience as not (very) positive (OR.7, 95% CI , P=0.01). Model performance: Hosmer Lemeshow test, P=0.79 and AUC=0.7 (95% CI ).. DISCUSSION The first and most important finding of this study is that no lay rescuers show PTSDrelated symptoms 6 weeks after providing bystander CPR and/or connecting an AED, even if their perceived shortterm psychological impact is bearable or severe. However, lay rescuers who perceive severe shortterm psychological impact show more often mild PTSDrelated symptoms. We identified three independent factors that were associated with a higher, albeit not clinically relevant, level of PTSDrelated symptoms: no AED connected by lay rescuer, lay rescuers who perceived severe shortterm psychological impact, and lay rescuers who rated their resuscitation experience as not (very) positive. The factor, no AED connected by lay rescuer, is not in line with what we expected and cannot be explained by the other investigated factors. To be included in the study, lay rescuers had to be actively involved in the resuscitation: if they did not connect an AED, they had to provide chest compressions or ventilations. However, these two factors did not show any association with a higher level of PTSDrelated symptoms.

13 70 Chapter Table.3 Univariable associations of resuscitation, outcome, and impact related characteristics with the Impact of Event Scale score None (0 8) n=153 Mild (9 25) n=36 OR (95% CI) Pvalue Resuscitation related factors, n (%) Bystander CPR prior to arrival lay rescuer* Yes No 76 (79) 77 (83) 20 (21) 16 (17) 0.8 (0. 1.6) 0.53 Order of arrival* 1 st lay rescuer >1 st lay rescuer 12 (80) 29 (88) 32 (21) (12) 0.5 ( ) 0.27 Chest compressions provided by lay rescuer* Yes No 117 (79) 36 (88) 31 (21) 5 (12) 0.5 ( ) 0.21 Ventilations provided by lay rescuer* No Yes, with mask Yes, without mask 78 (81) 3 (83) 1 (79) 18 (19) 7 (17) 11 (21) 0.9 ( ) 1.2 ( ) AED connected by lay rescuer* Yes No Problems encountered during resuscitation Yes No 9 (93) 10 (77) 88 (83) 65 (78) (8) 32 (2) 18 (17) 18 (22) 3.8 ( ) 1. ( ) Did perform CPR previously Yes No 9 (87) 59 (73) 1 (13) 22 (27) 2.5 ( ) 0.02 Outcome related factors, n (%) Patient transferred to ER No Yes Unknown 79 (81) 69 (80) 5 (83) 18 (19) 17 (20) 1 (17) 1.1 ( ) 0.9 (0.18.0) Patient discharged alive No Yes Unknown 117 (82) 12 (75) 2 (77) 25 (18) (25) 7 (23) 1.6 ( ) 1. ( ) Impact related factors, n (%) Perceived shortterm psychological impact* No/mild impact Bearable impact Severe impact 69 (89) 69 (79) 15 (63) 9 (12) 18 (21) 9 (38) 2.0 (0.8.8).6 ( ) <0.01 Talked to other people about their resuscitation experience Yes No 19 (81) (80) 35 (19) 1 (20) 0.9 ( ) 0.96 Perceived level of preparedness (More than) sufficient Not sufficient 19 (81) (80) 35 (19) 1 (20) 1.1 ( ) 0.96 Rating their resuscitation experience (Very) positive Not positive 13 (83) 10 (59) 29 (17) 7 (1) 3.5 ( ) 0.02

14 Psychological impact of lay rescuers performing CPR 71 Table.3 Continued AED indicates automated external defibrillator; CI, confidence interval; CPR, cardiopulmonary resuscitation; and ER, emergency department. * Answer to this question obtained through the online questionnaire that was send to all lay rescuers simultaneously with the text message alert. Answer to this question obtained through semistructured interview by telephone that was performed median three days after the resuscitation. Answer to this question obtained through the second telephone call to discuss the Impact of Event Scale that was sent median 32 days after the resuscitation. This category includes 59 lay rescuers who felt sufficiently prepared and 125 lay rescuers who felt more than sufficiently prepared. This category includes 2 lay rescuers who rated their experience as negative and 15 lay rescuers who rated their experience as neither positive nor negative. Of all interviewed lay rescuers who completed the IES, 91% regarded their experience as (very) positive. This is in line with the study from Axelsson et al., 7 who reported on bystanders experiences and reactions in Sweden. In this study, 93% of the bystanders rated their intervention as mainly positive. Comparison with other studies is difficult, since we are the first to report on perceived shortterm psychological impact in relation to PTSDrelated symptoms in lay rescuers performing bystander CPR. Others mainly studied PTSD in family members of OHCA patients, 1619 or reported on bystanders psychological reactions 7,8 and the importance of debriefing of bystanders. 20 Axelsson et al. 8 found two independent factors positively associated with bystanders psychological reactions, namely victim outcome and debriefing. Additionally, Møller et al. 20 reported that formally debriefing bystanders positively influences the ability to cope with emotional reactions. In our study, almost all lay rescuers talked to at least one person about their experience; only 19 (10%) also spoke to a professional. Our results suggest that lay rescuers do not necessarily need a professional to talk with after a resuscitation effort; in most cases, talking to someone in their social environment will probably be sufficient. Not finding PTSDrelated symptoms among our interviewed lay rescuers may be explained by the fact that the interview was a kind of debriefing. Some lay rescuers declared that telling their story to someone they do not know, helped them to deal with the psychological impact of the resuscitation. Also, 80 (2%) interviewees were offduty professional rescuers who may have been trained to better cope with stress than other lay rescuers. Furthermore, it is possible that higher stress scores are found when performing this study on bystanders who are not part of an organized system and are unprepared when confronted with a cardiac arrest.

15 72 Chapter.5 LIMITATIONS Our study has several limitations. First, one quarter of lay rescuers who filled out the online questionnaire may not be representative of all whom received a TMalert and a request to fill out the online questionnaire. Several reasons are possible for not filling out the online questionnaire. It is possible that people with very little/severe stress decided not to fill out the questionnaire. This might have introduced response bias. However, it is not possible to know the direction of such bias. Furthermore, we know that approximately five percent of all addresses are not correctly registered in the database of lay rescuers. Another reason is that lay rescuers, e.g. who did receive the TMalert but who did not arrive on scene, might have believed that they did not need to fill out the questionnaire. Finally, it is possible that lay rescuers who received the with the link to the questionnaire more than once, got tired of this questionnaire after a few times, especially, if they did not respond to the alert. Second, we used a screening questionnaire rather than a psychiatrist or psychologist interview to identify PTSDrelated symptoms. However, the Dutch IES is a validated instrument 13 and it has shown to be a stronger and better predictive scale than the Dutch IESrevised, which also covers symptoms of hyperarousal, the third symptom cluster in de diagnosis of PTSD symptomatology CONCLUSIONS Local lay rescuers who are alerted by text messages do not show clinically relevant PTSDrelated symptoms 6 weeks after performing bystander CPR, even if they perceive severe shortterm psychological impact. Moreover, the great majority of lay rescuers regarded their resuscitation experience as positive. These findings are important for all regions in the Netherlands that already alert lay rescuers as well as other regions or countries, that are considering using text messages to alert local lay rescuers. CONFLICT OF INTEREST STATEMENT Data collection for this study was made possible by grants from Cardiac Science (Waukesha, WI, USA), Defibtech (Guilford, CONN, USA), Philips Nederland B.V. (Eindhoven, the Netherlands), Physio Control Inc. (Redmond, WA, USA), and Zoll Medical (Chelmsford, MA, USA). JAZ is supported by a grant from the Dutch Heart Foundation (#2010T083). The funders had no access to the data and did not contribute to the preparation of this manuscript.

16 Psychological impact of lay rescuers performing CPR 73 ACKNOWLEDGEMENTS We would like to thank HartslagNu for their cooperation and support. Special thanks to all participating lay rescuers.

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19 76 Chapter SUPPLEMENTAL FIGURE On you experienced (date) (life event) FREQUENCY Below is a list of comments made by people after stressful life events. Please check each item, indicating how frequently these comments were true for you DURING THE PAST SEVEN DAYS. If they did not occur during that time, please mark the not at all column. Not at all Rarely Sometimes Often 1. I thought about it when I didn t mean to. 2. I avoided letting myself get upset when I thought about it or was reminded of it. 3. I tried to remove it from my memory.. I had trouble falling asleep or staying asleep because of pictures and thoughts about it that came into my mind. 5. I had waves of strong feelings about it. 6. I had dreams about it. 7. I stayed away from reminders of it. 8. I felt as if it hadn t happened or wasnt real. 9. I tried not to talk about it. 10. Pictures about it popped into my mind. 11. Other things kept making me think about it. 12. I was aware that I still had a lot of feelings about it, but I didn t deal with them. 13. I tried not to think about it. 1. Any reminder brought back feelings about it. 15. My feelings about it were a kind of numb. Intrusion subset = 1,, 5, 6, 10, 11, 1; avoidance subset = 2, 3, 7, 8, 9, 12, 13, 15. Supplemental Figure.1 The Impact of Event Scale.12 Respondents are asked to rate the items on a point scale according to how often each has occurred in the past seven days: 0 (not at all), 1 (rarely), 3 (sometimes), and 5 (often). A score of 26 indicates a clinical significant stress reaction.