Suffocation Injuries in the United States

Patient Characteristics and Factors Associated With Mortality

Roula Sasso, MD; Rana Bachir, MPH; Mazen El Sayed, MD, MPH


Western J Emerg Med. 2018;19(4):707-714. 

In This Article


This study examined suffocation injuries in a large national sample of ED visits; it is the largest study to date to report on this medical condition and to attempt to identify its burden using a national sample in the U.S. While the mechanisms of injury resulting in suffocation and asphyxiation are numerous, several forms of asphyxiation are uncommon and under-reported. This is evident in the medical literature with several forms of asphyxiation described only in case reports or case series.[21,22]Some studies have reported mortality rates in more common forms of suffocation injuries such as hanging and strangulation.[10,17,18,23,24] Our study, however, addressed all forms of suffocation injuries using a national sample, in an attempt to identify the burden of this disease and avoid overlooking under-reported and uncommon forms of injury that result in suffocation and asphyxiation.

The incidence of suffocation injury in 2013 among ED patients was 20 per 100,000 individuals, and the mortality rate was 10.9% (95%CI [10.1–11.7]) with varying mortality rates, ranging from 9.6% (suicide and self-inflicted injury by hanging, strangulation, and suffocation) to 30.7% (undetermined if self-inflicted or accidental). A study in Japan showed a 77% mortality rate in individuals presenting with suicidal-intent hanging injury,[17] whereas another study in Australia showed a mortality rate of 12% for the same form of injury.[18] This discrepancy in mortality rates could be attributed to different factors including lack of standardized management of suffocation injuries,[25–27] higher injury acuity, or different groups of patients included in other studies.

Additionally, 47.4% of patients in this study had a mental health condition and 40.1% had intentional injury reported. These results are in line with previous studies suggesting that suffocation injuries are commonly a result of intentional self-harm or suicidal attempt and are likely to occur in patients with a history of psychiatric disorders.[23] In fact, a previous study examining deaths in adolescents due to hanging injury revealed that the majority of hangings (98.4%) were the result of a suicidal attempt.[28] Similarly, deaths due to plastic-bag suffocation were mostly in adults and resulted from suicidal attempts.[22] Our results also showed that intentional self-harm was associated with higher odds of mortality after controlling for confounding factors in the multivariate analysis. While the literature assessing the impact of intentional injury on mortality in patients with suffocation injuries is scarce, studies exploring this impact in injury/trauma patients in general have reported higher mortality associated with intentional injury.[30,31]

Males were both more likely to present with and die from suffocation injuries. The available published literature reports conflicting data on the gender role in suffocation injuries by hanging.[12,17,18,23,26] by inhalation of helium gas,[6,32] by plastic-bag suffocation,[22] and by autoerotic asphyxiation.[21] The various mechanisms of suffocation may have contributed to this inconsistency in impact of gender on outcomes after suffocation. Other confounding factors such as intentional injury may also explain this inconsistency. Several studies have suggested that suffocation related to suicidal intent is more common in males,[9,32,33–35] while suffocation related to assault or homicidal intent is more likely to occur in females.[5,36,37]

Patients aged 4–18 years were observed to have higher odds of mortality compared to other age groups. The existing literature does not provide clear evidence for this. However, some studies suggest that children are more vulnerable to have complete airway obstruction and are more prone to delayed airway edema after strangulation, due to the relatively small size of the airway.[38,39] Additionally, we can speculate that children are more likely than adults to experience prolonged unintentional suffocation as they are often left unattended and incapable of self-help. More research investigating the relationship between age and mortality among patients with suffocation injuries could help develop age-specific prevention strategies.

This study also showed that individuals with disease of the circulatory system, nervous system, respiratory system and genitourinary systems are significantly more likely to die from suffocation injuries. This was expected since patients with baseline cardiac, respiratory and kidney diseases are more likely to have poorer clinical outcomes.[40–42] Mental disorders seemed to be negatively associated with mortality in patients presenting with suffocation injuries. While mental disorders are associated with higher natural and unnatural cause mortality,[43] some studies have demonstrated mental disorders to be protective in trauma patients.[44,45] Individual with suffocation injuries who survive are more likely to undergo psychiatric disease evaluation and to get diagnosed in the ED and in hospital with a psychiatric disorder, which may result in a higher frequency of mental disorders in surviving patients. Additionally, patients could suffer from psychiatric disorders that are a result of the traumatic injury experienced. However, further studies are needed to evaluate the effect of pre-existing mental disorders on patients with suffocation injuries.