Hanging-associated out-of-hospital cardiac arrests in Melbourne, Australia
- Conor Deasy1,2,3,
- Janet Bray1,
- Karen Smith1,2,
- Stephen Bernard1,2,3,
- Peter Cameron2,3 On behalf of the VACAR Steering Committee
- 1Ambulance Victoria, Melbourne, Australia
- 2Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Victoria, Australia
- 3Alfred Hospital, Melbourne, Australia
- Correspondence to Dr Conor Deasy, Department of Epidemiology and Preventive Medicine, Monash University, The Alfred Centre, 5th Floor, 99 Commercial Road, Melbourne 3004, Australia;
Contributors All authors have made substantial contributions to all of the following: (1) the conception and design of the study, (2) drafting the article or revising it critically for important intellectual content, and (3) the final approval of the version to be submitted.
- Accepted 27 January 2012
- Published Online First 16 March 2012
Introduction Hanging is an infrequent but devastating cause of out-of-hospital cardiac arrest (OHCA). We determine the characteristics and outcomes of hanging-associated OHCA in Melbourne Australia.
Methods A 10-year retrospective case review of all adult hangings (aged ≥16 years) associated with OHCA, was conducted using data from the Victorian Ambulance Cardiac Arrest Registry.
Results Between 2000 and 2009, the emergency medical service (EMS) attended 33 178 adult OHCAs of which 1321 (4%) had hanging as the aetiology. The median age (IQR) of hanging-associated OHCA cases was 39 (29–51) years and 1162 were men (88%). The first recorded rhythm by EMS was asystole seen in 1276 (75.5%) patients, pulseless electrical activity (PEA) in 38 (13.4%) cases and ventricular fibrillation in 7 cases (0.5%). EMS attempted resuscitation in 208 (15.7%) patients of whom 61 (29.3%) achieved return of spontaneous circulation (ROSC) and were transported, and 7 (3.3%) survived to hospital discharge. Hanging-associated OHCAs were younger (median (IQR) 38 (29–51) years versus 74 (61–82) years, p<0.001), less likely to have a shockable rhythm (0.5% vs 17.2%, p<0.001), receive bystander cardiopulmonary resuscitation (14.1% vs 25.5%, p<0.001) or an attempted resuscitation by EMS (15.7% vs 36.1%, p<0.001) compared with OHCA cases with an aetiology of ‘presumed cardiac’ arrest. Multivariable logistic regression identified factors associated with EMS decision to attempt resuscitation; the adjusted OR (95% CI) for ‘presence of bystander cardiopulmonary resuscitation’ was 15.8 (10.70–23.30) and for ‘witnessed arrest’ was 5.26 (1.17–23.30).
Conclusion Attempted resuscitation was not always futile with a survival of 3.3%. A preventive focus is needed.
Hanging is a frequently used method of committing suicide in many countries.1 ,2 Death from hanging has increased over the last 30 years where an increase in suicidal hanging, particularly among young men has been reported3; this may be as a result of reduced access to alternative methods of suicide through successful preventive strategies.4 Attempted hanging has a high death rate estimated at over 83%.5
There is little literature regarding hanging-associated out-of-hospital cardiac arrest (OHCA) and very limited data available on the subsequent quality of life of survivors. Previous studies have described outcomes of patients presenting to hospitals with OHCA due to hanging;6 however, such studies do not reflect the complete picture as many patients are not being transported to hospital. Similarly, forensic publications may not capture those patients who survive to be admitted to hospital and their subsequent course. Using a population-based cardiac arrest registry allows a more complete representation of the epidemiology and outcomes of hanging-associated OHCA.
A clinician's perception of the likely outcome of resuscitation may influence their behaviour during the resuscitation—be that how aggressively they resuscitate or how readily they withdraw. Penney et al found that victims without spontaneous cardiac output at scene did not survive, even if cardiopulmonary resuscitation (CPR) was successful initially;7 however, since this publication, there have been case reports8 and case series6 reporting survivors of OHCA caused by hanging.
This study aims to describe the characteristics and profile of adult hanging OHCA in Melbourne, Australia.
The state of Victoria has a population of 5.3 million with approximately 4 million residing in metropolitan Melbourne. The emergency medical service (EMS) comprises ambulance paramedics who have some advanced life support skills (laryngeal mask airway, intravenous epinephrine) and mobile intensive care ambulance (MICA) paramedics who are authorised to perform endotracheal intubation, rapid sequence induction, Pneumocath insertion and administration of a wider range of drugs. The basic qualification for paramedics in Australia is a 3-year bachelor's degree in Health Sciences. MICA paramedics are experienced paramedics who undergo a university-level postgraduate diploma in Intensive Care Paramedical Practice. The Advanced Medical Priority Dispatch System is operational in Melbourne. MICA paramedics are dispatched to patients with critical illness, including patients with cardiac arrest. In addition, firefighters are dispatched to patients with suspected cardiac arrest in the inner two-thirds of Melbourne.9 EMS response time is the time from ‘000/112/999’ call to arrival at scene. The pre-hospital cardiac arrest protocols follow the recommendations of the Australian Resuscitation Council.7 ,10 Ambulance Victoria paramedics are not obliged to commence resuscitation when the injuries are inconsistent with life. This includes decapitation, presence of rigor mortis, decomposition or postmortem lividity, where death has been declared by a Medical Officer who is or has been at the scene, and where the presenting rhythm was monitored as asystole for >30 s, and there has been >10 min downtime with no evidence of hypothermia, drug overdose or family/bystander objections. Paramedics may discontinue resuscitation if advanced life support has been performed for 30 min without return of spontaneous circulation (ROSC), the rhythm is not ventricular fibrillation (VF) or ventricular tachycardia (VT), there are no signs of life, no gasps or evidence of pupillary reaction and no evidence of hypothermia or drug overdose.10
The Cerebral Performance Category (CPC) scale11 is used to summarise the level of neurological function. A score of 1 is achieved if the patient is conscious, alert and able to work, though the patient may have a mild neurological or psychological deficit. CPC 2 is a moderate cerebral disability: the patient is conscious with sufficient cerebral function for independent activities of daily life and able to work in a sheltered environment. CPC 3 is a severe cerebral disability: the patient is conscious, dependent on others for daily support because of impaired brain function. This can range from an ambulatory state to severe dementia or paralysis. CPC 4 is when the patient is in a coma or vegetative state. It is a state of unawareness (vegetative state) without interaction with the environment; the patient may have spontaneous eye opening and sleep/wake cycles. CPC 5 represents the state of brain death.
Since December 2007, the majority of paramedics in Melbourne have documented patient details and management in an electronic patient care record (PCR). Documentation in previous years involved a paper-based PCR. Selected data from PCRs is collected for all cases of OHCA and stored in the Victorian Ambulance Cardiac Arrest Registry (VACAR). VACAR also includes some data from the hospital records for those cases transferred to hospital, including length of stay, discharge direction from hospital and outcome. Since 2005, VACAR has collected data on the details of the trauma. Immediate surgery, mechanical ventilation and discharge direction were also available from this time.
VACAR was searched for all OHCAs occurring due to hanging in those aged ≥16 years. We compared these with OHCAs with an aetiology of ‘presumed cardiac’ arrest. This included OHCAs occurring in the presence of EMS. Cross-checking against coronial and hospital records was performed.
VACAR has been classified as a quality assurance project by the ethics committee at the Department of Health. The collection of cardiac arrest outcome data by VACAR was approved by the ethics committees of Melbourne hospitals receiving cardiac arrests by ambulance. This study was approved by the Research Committee of Ambulance Victoria and Monash University Human Research Ethics Committee.
All data were entered into an Access software cardiac arrest registry database V.2003 (Microsoft, Redmond, WA, USA). Statistical calculations were performed on STATA software V.10.0 (Stata Corporation). χ2 test was used to determine differences for categorical variables, with a p value <0.05 regarded as statistically significant. Continuous variables were compared using the t-test (normal distribution) or Mann–Whitney U test.
Factors affecting paramedic's attempting resuscitation were examined in a multivariable logistic regression analysis adjusting for Utstein variables. The year of arrest did not have a linear relationship with the odds of EMS attempting resuscitation; therefore, the years 2000–2006 which bore consistency were grouped together as referent, and subsequent years as categorical variables. The OR for location of arrest is given in reference to arrest occurring at home.
Between 2000 and 2009, EMS attended 33 178 adult OHCAs of which the aetiology of 1321 (4%) was hanging. Figure 1 shows the aetiology of the adult OHCA. Hanging-associated OHCAs were younger, more likely to be men and less likely to have a shockable rhythm of VF/pulseless VT compared with OHCA cases with ‘presumed cardiac’ arrest aetiology (table 1). Hanging-associated OHCAs were less likely to receive bystander CPR and attempted resuscitation by EMS compared with ‘presumed cardiac’ arrest cases (table 1).
There were seven patients who survived to leave hospital alive giving a survival rate (where EMS attempted resuscitation) of 3.3%. Where the presenting rhythm was shockable (n=2), the CPC scores were CPC 1 and 4, where the presenting was pulseless electrical activity (PEA) (n=4) the CPC score was 1 in three cases, and the CPC was 2 in the fourth case, and where the presenting rhythm was asystole the CPC was 1. The median (IQR) age of survivors was 28 (18–46) years.
The patient resuscitated from the asystolic OHCA was aged 46 years, had a maximum down time of 10 min from when last seen alive to being found hanging. He received immediate CPR by a family member and the ambulance response time was 4 min 30 s.
Bystander CPR was performed in 14.1% (n=182) of all hanging-associated OHCAs attended by EMS. Of patients who were subsequently transported having achieved ROSC (n=61) there were 31 (51%) patients who had received bystander CPR, while 12.3% (n=151) of those who were not transported had received bystander CPR (p<0.001). Of the patients discharged alive, bystander CPR had been performed in three cases (43%).
Multivariate logistic regression identified factors associated with EMS's decision to attempt resuscitation in both hanging-associated and OHCA with ‘presumed cardiac’ arrest aetiology; the adjusted OR (95% CI) for ‘presence of bystander CPR’ was 15.8 (10.70–23.30) and for ‘witnessed arrest’ was 5.26 (1.17–23.30) for hanging-associated OHCA, while for presumed cardiac arrest the adjusted OR (95% CI) was 6.91 (6.32 to 7.55) for ‘presence of bystander CPR’, and an adjusted OR (95% CI) of 12.6 (11.58 to 13.70) for ‘witnessed arrest’ (table 2).
This is the largest case series to date describing hanging-precipitated OHCA in adults. Factors known to improve survival were much lower in the hanging group where lower proportions of witnessed arrest, bystander CPR and shockable rhythm OHCAs were seen. This study shows that although results are poor, some patients do survive to leave hospital (3.3%) and do so with a favourable neurological outcome in most cases.
While there has been a decline in suicide cases in Australia, hanging has increased and is now the most common method of completed suicides1 in all age groups. Large et al 1 reported an increased incidence of hangings in men, 5.65 per 100 000 men for the period 1988–1997 increasing to 7.38 per 100 000 men for the period 1998–2007 in Victoria, while the overall suicide rate dropped from 19.3 to 16.2 per 100 000 over these 2 decades.
The mechanism of death in deliberate and accidental hanging is debated; however, it is most likely due to vascular obstruction of neck vessels and cerebral hypoxia. Airway injuries severe enough to interfere with airway management are uncommon,12 ,13 and although airway disruption has been described, airway closure is not thought to be a significant factor13 ,14 as death from hanging has been described in tracheostomised patients.15 ,16
Wee et al performed a retrospective review examining the victims of OHCA due to hanging who presented to a tertiary general hospital from January 2000 to December 2009 in South Korea where EMS provides basic life support. A total of 52 patients with OHCA due to hanging presented to the hospital during the study inclusion period, all of whom were in arrest at the scene and at the time of hospital arrival. Pre-hospital EMS CPR was done in 34 cases (65.4%), and in-hospital resuscitation was attempted in 31 cases (60%). ROSC was achieved in 13 (42%) and 5 (16%) of those who had an attempted resuscitation. However, all patients who survived to be discharged from hospital had a CPC of 4.6 Their single-centre study showing a higher survival than that seen in Melbourne but with globally poor neurological outcome may suggest a more aggressive resuscitation culture and highlight the value of pre-hospital advanced life support.
Matsuyama et al in a study performed on hangings presenting to a single centre in Japan found 75% of survivors received bystander CPR at the scene, whereas only 27.8% of non-survivors received CPR at the scene and suggested that an increased survival rate could have been achieved in non-survivors if CPR had been performed promptly.17 In our study, bystander CPR was performed in 14.1% of all hanging-associated OHCAs attended which is less than that seen in other aetiologies of OHCA. Bystander CPR was associated with an increased likelihood of paramedics attempting resuscitation and proportionally more patients who received bystander CPR were transported with ROSC. Multiple studies have surveyed a variety of groups regarding their willingness to perform bystander CPR, and have identified a host of barriers, among them are composure to act, physical inability to perform bystander CPR, legal liability, transmission of infectious diseases.18–20 Therefore, a successful strategy to improve bystander CPR will incorporate a variety of measures21 enabling timely identification of arrest, encouragement and empowerment of bystanders to act and provision of effective CPR by them when they do.22 The realities of this in the context of an arrested hanging patient, often a relative of the bystander, are significant.
The most important factor for an increased chance of survival from OHCA is whether the patient is found in VF or pulseless VT. The chance of survival then increases about 5–10 times.23 ,24 Each minute of delay before defibrillation reduces the probability of survival to discharge by 10–12%.25 ,26 However, these studies refer, in general, to OHCA with ‘presumed cardiac’ arrest aetiology and may not be applicable to the hanging OHCA scenario where the mechanism of death is likely to be cerebral hypoxia. In this study, shockable rhythm was present in only 0.5% (n=7) of hanging-associated OHCAs.
The paramedic's decision to resuscitate was examined using multivariable analysis. Given that they work within clinical practice guidelines10 that allow them to not commence resuscitative efforts, the extent to which the presence of bystander CPR influences their decision to proceed with an attempted resuscitation is noteworthy.
Therapeutic hypothermia attenuates ischaemic brain damage and may have a role in the post-resuscitation link in the chain of survival for hanging-associated OHCA victims who achieve ROSC; this has been described in a number of case series and case reports.27 It is unlikely that this will ever be shown in a randomised controlled trial as the logistics of achieving the numbers of recruitments required to show an outcome benefit in a condition where the mortality is so high making it unfeasible.
The most likely successful intervention to improve outcomes from OHCA (especially hanging), is preventing the event occurring in the first instance, that is, addressing the first link in the chain of survival.28 The reduction in suicides in Australia has been influenced by Australia's national suicide prevention strategy29 which has included measures to reduce the availability of some lethal methods of committing suicide, including the firearms ‘buy-back’ scheme,30 ,31 the introduction of catalytic converters in all new cars,32 changes in the pattern of prescription of antidepressant medications away from tricyclic antidepressants, an increase in the use of the less toxic serotonin re-uptake inhibitors,33 paracetamol pack size changes and safety measures at jumping sites.29 However, hanging poses a challenge to such suicide prevention strategies; applying a ‘means reduction’ approach to an entity such as hanging where materials are so readily available, most would agree, is unlikely to work outside of institutions housing at-risk clients.2 ,34 As a method of suicide, hanging in contrast to overdose, allows little opportunity for a change of mind in the victim as death generally occurs rapidly with suspension. Biddle et al 35 in their qualitative study report a perception that hanging is considered to be a certain, quick, clean, painless death with little awareness of dying and easy to perform. They suggest prevention strategies be focused on more accurate information about the processes and consequences of hanging, increasing awareness of the possibility of neurological impairment on survival, and a focus on the effect on family members who discover the hanging body. They acknowledge that messages that may deter some individuals might provide encouragement to others. At a population level, the challenge is therefore to devise disguised and implicit messages that can bring about change in lay knowledge.35 At an individual patient level, suicide prevention is possible; 83% of suicides have had contact with their primary care physician within a year of their death, and 66% within a month.36 ,37 A key prevention strategy is improved screening of depressed patients by primary care physicians and better treatment of major depression.4
This study was performed using retrospective registry data from an urban setting. Important predictors of survival, such as hanging time and contact with ground, were not reliably ascertainable from the patient's ambulance or hospital records. The factors associated with the physician's decision to proceed with active treatment, or palliate a patient who arrived at hospital having achieved ROSC, were beyond the scope of this study. The CPC,11 ascertained from the survivor's hospital chart may not be optimal in reflecting true functional outcomes in this group of patients, and a more nuanced outcome measure incorporating quality-of-life measures would be particularly helpful here.
In this study, it is shown that paramedic-delivered EMS-attempted resuscitation for hanging-associated OHCA was not always futile with a survival of 3.3%. Strategies to decrease the high mortality rate of hanging-associated OHCA may need to focus on prevention of this devastating act.
Ambulance Victoria paramedics. Vanessa Barnes and Marian Lodder and staff at VACAR, Ambulance Victoria. Professor Belinda Gabbe, Dept of Epidemiology and Preventive Medicine for statistical advice.
Competing interests None.
Patient consent The VACAR cardiac arrest registry from which this data was ascertained is considered a quality assurance tool.
Ethics approval This study was approved by the Monash University Human Research Ethics Committee.
Provenance and peer review Not commissioned; externally peer reviewed.