Clinical paperCharacteristics and outcome among patients suffering out-of-hospital cardiac arrest due to drowning☆
Introduction
During the last century, the number of drownings in Sweden has decreased. According to the Swedish lifesaving society—SLS, around 1000 persons or 19.2/100,000 inhabitants drowned in Sweden in the late 1800s. An average over the last 10 years 1997–2006, show 1.2/100,000 drownings per year.1 The number of drownings are even higher when intentional, homicidal and unclear cases are added as in the National board of health and welfares register over causes of death, which are based upon the ICD10 code system. In 2003 they reported 246 drownings or 2.74/100,000 inhabitants, of these were 25% intentional drownings.2 There also appears to be an increase in drownings during summers with higher water temperatures and more recreational activities. The aquatic environments are more frequently visited today than they were 100 years ago, however the relationship between swimming ability and drowning risk is still pretty much unknown.3 A patient with cardiac arrest caused by drowning presents with a specific problem. It is often difficult to reconstruct the course of the event and the initial intent of the victim, as some drownings are intentional. Drowning also often occurs in rural settings, such as lakes, ponds or streams, with an expected prolonged ambulance response time.
The aim of this study is to describe the characteristics and survival of patients suffering out-of-hospital cardiac arrest (OHCA) caused by drowning. The results will be compared with the traditional out-of-hospital cardiac arrest, outside the home, where the arrest is judged to be caused by a cardiac etiology.
Section snippets
Patients
Patients suffering a cardiac arrest to whom an ambulance was called were included in the registry, with the exception of patients who had obviously been dead for a long time and whose bodies were therefore not taken to hospital by the ambulance crew. For the others, the standardised form was completed by the ambulance crew.
Registry
This study is based on material collected by the Swedish Cardiac Arrest Registry, which is a joint venture between the Federation of Leaders In Swedish Ambulance and
Results
In all, 40,503 patients who suffered an out-of-hospital cardiac arrest in whom CPR was started were evaluated for inclusion in this survey. Among them 4,770 were crew witnessed and therefore excluded. Among the remaining 35,733 patients information on the cause of cardiac arrest was missing in 2,790 patients (8%). Among the remaining 32,943 patients, the OHCA was judged to be caused by drowning in 299 patients (0.9%), while it was judged to be caused by a cardiac etiology outside home in 7494
Univariate analysis (Tables 1 and 2 and Figures 1 and 2)
As shown in Table 1, among patients with OHCA outside home survival to hospital admission was higher among patients with OHCA due to drowning as compared with OHCA due to cardiac etiology. However, survival to 1 month did not significantly differ between the two groups.
As shown in Table 2 and Figure 1 (all patients with OHCA due to drowning included), survival was associated with age, with higher survival among younger patients, and with ambulance response time. Survival was markedly higher
Overall results
The survival rate to 1 month among patients with OHCA outside home caused by drowning did not differ significantly from that among patients with OHCA caused by a cardiac etiology. Survival was most markedly associated with ambulance response time.
Although cardiac arrests caused by drowning are less frequently witnessed, bystanders are often willing to commence CPR in these cases particularly in the younger age groups.
Age
People of all ages come in contact with aquatic environments at one time or
Implications
Although survival among patients with OHCA due to drowning appeared to be relatively high, almost nine in every 10 patients did not survive to 1 month. Although we must aim to reduce the ambulance response time still further, there are practical obstacles to achieving this goal.
Although bystander CPR was not significantly associated with increased survival, the study was underpowered to address this question adequately. In all probability, bystander CPR will increase survival in this OHCA
Limitation
There was missing information in nearly all the variables that were evaluated.
Conclusion
Among patients suffering from OHCA in whom CPR was attempted and who were included in the Swedish Cardiac Arrest Registry, 0.9% of the OHCA were caused by drowning. These patients had a relatively high survival rate to 1 month (11.2%) which did not significantly differ from survival among patients with OHCA of a cardiac etiology outside home. The factor that was most strongly associated with survival was the ambulance response time and much higher survival was found among patients with a
Conflict of interest statement
There are no financial or other relations that might pose a conflict of interests.
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A Spanish translated version of the summary of this article appears as Appendix in the final online version at 10.1016/j.resuscitation.2007.09.003.