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.

Abstract and Introduction

Abstract

Introduction: Asphyxiation or suffocation injuries can result in multi-organ damage and are a major cause of morbidity and mortality among different age groups. This study aims to describe characteristics of patients presenting with suffocation injuries to emergency departments (EDs) in the United States (U.S.) and to identify factors associated with mortality in this population.

Methods: We conducted a retrospective cross-sectional study using the 2013 U.S National Emergency Department Sample database. ED visits with primary diagnoses of intentional or accidental suffocation injury, and injury by inhalation and aspiration of foreign bodies or food (ICD-9-CM codes) were included. We performed descriptive statistics to describe the study population. This was followed by multivariate analyses to identify factors associated with mortality.

Results: We included a total of 27,381 ED visits for suffocation injuries. Most suffered from either inhalation and ingestion of food causing obstruction of respiratory tract or suffocation (51.6%), or suicide and self-inflicted injury by hanging, strangulation, and suffocation (39.4%). Overall mortality was 10.9%. Over half (54.7%) of the patients were between 19 and 65 years old. Males were more common than females (59.1% vs. 40.9%). Over half of the patients (54.9%) were treated and released from the ED. Factors associated with increased mortality included male gender, young age (4-18 years), diseases of the cardiac, respiratory, genitourinary and neurologic systems, intentional self-harm, and self-payer status.

Conclusion: Mortality from suffocation injuries remains high with significant burden on children and adolescents and on patients with intentional injuries. Tailored initiatives targeting identified modifiable factors through implementation of behavioral and environmental change can reduce the risk of suffocation injury and improve clinical outcomes of affected victims.

Introduction

Asphyxiation or suffocation can be defined as the deprivation of oxygen supply to body tissues and can result from mechanical or non-mechanical constriction of the airway or from a decrease in breathable gas in the respired surrounding atmosphere.^[1] Suffocation and asphyxiation can vary at the forensic pathology level;^[1] however, both can be used interchangeably to report a decrease in oxygen delivery to the lungs resulting in deprivation of oxygen or hypoxia.^[2,3]

Suffocation injuries and death can result from suicidal attempt, assault or accidental injury. In parts of Europe and Asia, intentional asphyxiation by hanging is the leading manner of suicide attempts.^[4,5] In the United States (U.S.), the rate of suicide by intentional asphyxiation is second only to suicide by firearms.^[6] Choking is a form of unintentional asphyxiation: choking was the third leading cause of unintentional deaths in the U.S. between 2000 and 2013 in adults aged 65 years or older^[7] and a leading cause of morbidity and mortality among children aged less than 3 years.^[8] In addition to death and multi-organ damage, complications of asphyxiation include cardiopulmonary injuries and neurological injuries, in addition to orthopedic injuries with hangings and strangulation.^[9–11]

The current medical literature describing suffocation injuries and clinical outcomes is limited and is mostly focused on death from asphyxiation by hanging or strangulation injuries.^[12–16] Available medical literature suggests that cardiopulmonary resuscitation at the scene of suffocation injury is associated with improved clinical outcomes while longer duration of hanging is associated with increased mortality in cases of hanging asphyxiation.^[17] Low Glasgow Coma Scale on arrival to the emergency department (ED) has also been associated with poor clinical outcomes.^[18] Understanding the epidemiology of suffocation injuries, characteristics of affected victims and factors associated with mortality is important for physicians and policymakers to tailor prevention initiatives and mitigation strategies.

Our goal was to describe the characteristics of patients presenting with suffocation injuries to EDs in the U.S and to identify factors associated with mortality in this population.

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Table 1. International Classification of Disease - 9 - Clinical Modification (ICD-9-CM) codes with injury description.
Injury description	ICD-9 CM codes	N (%)
Accidental mechanical suffocation	E913.0, E913.1, E913.2, E913.3, E913.8, E913.9	602 (2.2)
Suicide and self-inflicted injury by hanging, strangulation, and suffocation	E953.0, E953.1, E953.8, E953.9	10,765 (39.3)
Hanging, strangulation, or suffocation, undetermined whether accidentally or purposely inflicted	E983.0, E983.1, E983.8, E983.9	513 (1.9)
Inhalation and ingestion of food causing obstruction of respiratory tract or suffocation	E911	14,140 (51.6)
Asphyxiation and strangulation	994.7	4,565 (16.7)

Table 2. Study characteristics of patients with suffocation injuries.
Characteristics	Frequency (N=27381)	Percentage (95% CI)
Gender
Male	16173	59.1 (57.9 – 60.2)
Female	11209	40.9 (39.8 – 42.1)
Age
Newborn -3	2057	7.5 (6.9 – 8.1)
4 -18	3892	14.2 (13.4 – 15.1)
19 – 65	14972	54.7 (53.5 – 55.9)
≥66	6446	23.6 (22.6 – 24.6)
Chronic conditions
Chronic conditions	19943	72.8 (71.8 – 73.9)
No chronic conditions	7438	27.2 (26.1 – 28.2)
Body system indicator¹
Injury and poisoning	21951	80.2 (79.2 – 81.1)
Mental disorders	12968	47.4 (46.2 – 48.5)
Factors influencing health status and contact with health services²	9659	35.3 (34.2 – 36.4)
Symptoms, signs, and ill-defined conditions	9298	34.0 (32.9 – 35.1)
Diseases of the circulatory system	9007	32.9 (31.8 – 34.0)
Injury diagnosis reported on record
Injury reported	21995	80.3 (79.4 – 81.2)
No injury diagnosis reported	5386	19.7 (18.8 – 20.6)
Method of injury³
Injury by assault	940	3.4 (3.0–3.9)
Injury by poisoning	535	2.0 (1.7–2.3)
Injury by falling	328	1.2 (1.0–1.5)
Injury by cutting or piercing	309	1.1 (0.9–1.4)
Injury from being struck	273	1.0 (0.8–1.3)
More than one injury diagnosis reported on record
One or no injury diagnosis reported	23728	86.7 (85.8 – 87.4)
More than one injury diagnosis reported	3654	13.3 (12.6 – 14.2)
Injury severity score
Minor trauma (0-15)	27239	99.5 (99.3 – 99.7)
Major trauma (16-75)	130	0.5 (0.3–0.7)
Intentional self-harm indicated on record
Intended self-harm	10967	40.1 (38.9 – 41.2)
No intended self-harm	16414	59.9 (58.8 – 61.1)
Season of admission
Summer	6325	26.4 (25.2–27.5)
Spring	6188	25.8 (24.7–26.9)
Autumn	6073	25.3 (24.2–26.4)
Winter	5411	22.5 (21.5–23.6)
Admission day
Monday – Friday	19675	71.9 (70.8 – 72.9)
Saturday - Sunday	7706	28.1 (27.1 – 29.2)
Urban-rural location of patient residence
Large central metropolitan	6721	24.8 (24.1 – 25.5)
Medium metropolitan	6196	22.8 (22.2 – 23.5)
Large fringe metropolitan	5718	21.1 (20.4 – 21.8)
Micropolitan	3271	12.1 (11.6 – 12.5)
Small metropolitan	2871	10.6 (10.0 – 11.2)
Not metropolitan or micropolitan	2356	8.7 (8.3 – 9.1)
Primary expected payer
Medicare	7991	29.3 (28.3 – 30.4)
Medicaid	6023	22.1 (21.1 – 23.1)
Private including Health Maintenance Organization (HMO)	7225	26.5 (25.5 – 27.6)
Self-payer	3836	14.1 (13.3 – 14.9)
No charge	242	0.9 (0.7 – 1.1)
Other	1916	7.0 (6.4 – 7.7)
Median household income
$1 - $37,999	7417	28.0 (27.0 – 29.0)
$38,000 - $47,999	7496	28.3 (27.3 – 29.4)
$48,000 - $63,999	6582	24.9 (23.9 – 25.9)
$64,000 or more	4987	18.8 (18.0 – 19.7)

CI, Confidence Interval.
¹Only the five most common body system indicators are shown. Other body system indicators listed from most to least frequent are as follows: (1) Disease of the respiratory system; (2) endocrine, nutritional and metabolic disease and immunity disorders; (3) diseases of the nervous system and sense organs, (4) disease of the digestive system; (5) diseases of the musculoskeletal system; (6) diseases of the genitourinary system; (7) disease of the blood and blood-forming organs; (8) infectious and parasitic disease; (9) diseases of the skin and subcutaneous tissue; (10) neoplasms; (11)congenital anomalies; (12) certain conditions originating in the perinatal period; and (13) complications of pregnancy, childbirth and the perineum.
²Includes (1) newborns and infants; (2) vaccinations and inoculations; (3) suspected exposure to communicable diseases; (4) patients who are either a carrier of a disease or have the sequelae or residual of a past disease or condition; (5) patient's past medical condition that no longer exists and is not receiving any treatment, but that has the potential for recurrence or patients with family member(s) who has had a particular disease that causes the patient to be at higher risk of also contracting the disease; (6) screening encounter;, (7) observational encounters; (8) aftercare encounters; (9) follow-up encounters; (10) donors; (11) counseling encounters,;(12) encounters for obstetrical and reproductive services; (13) routine and administrative examinations; and (14) miscellaneous encounters.
³Only the five most common Injury methods are shown: Other Injury methods listed from most to least frequent are as follows: (1) injury involving motor vehicle traffic; (2) injury involving natural or environmental causes; and (3) injury by fire, flame, or hot objects.

Table 3. Outcomes after suffocation injuries.
Outcomes – categorical variables	Frequency (N=27381)	Percentage (95% CI)
Disposition from the ED
ED visit in which the patient is treated and released	15041	54.9 (53.8 – 56.1)
ED visit in which the patient is admitted to the same hospital	9210	33.6 (32.6 – 34.7)
ED visit in which the patient is transferred to another short-term hospital	1941	7.1 (6.5 – 7.7)
ED visit in which the patient died in the ED	1076	3.9 (3.5 – 4.4)
ED visits in which patient was not admitted, destination unknown	112	0. 4 (0.3 – 0.6)
Death
Death in ED/hospital	2976	10.9 (10.2 – 11.7)
No death	24280	89.1 (88.3 – 89.8)
Outcomes-continuous variables	N	Mean (95% CI)
Total charge for ED ($)	27358	3620.2 (3531.6 – 3708.7)
Length of stay (days)	9210	6.2 (5.8 – 6.6)

CI, confidence interval, ED, emergency department.

Table 4. Factors associated with mortality after suffocation injury.
Variables	Odds ratio	95% CI	P value
Gender
Female	1.0	-	-
Male	1.3	1.1–1.6	0.008
Age (years)
≥66	1.0	-	-
19 – 65	1.2	0.9–1.6	0.256
4 -18	2.2	1.4 -3.4	0.001
0 – 3	0.9	0.5–1.8	0.912
Admission day
Weekend	1.0	-	-
Weekday	0.8	0.7–1.0	0.078
Body system indicators
Diseases of the circulatory system (No)	1.0	-	-
Yes	11.6	8.8–15.1	<0.001
Diseases of the nervous system and sense organs (No)	1.0	-	-
Yes	3.0	2. 5–3.8	<0.001
Diseases of the respiratory system (No)	1.0	-	-
Yes	1.9	1.6–2.4	<0.001
Diseases of the genitourinary system (No)	1.0	-	-
Yes	1.5	1.1–1.9	0.003
Factors influencing health status and contact with health services (No)	1.0	-	-
Yes	0.8	0.7–0.9	0.010
Diseases of the digestive system (No)	1.0	-	-
Yes	0.6	0.4–0.7	<0.001
Diseases of the musculoskeletal system (No)	1.0	-	-
Yes	0.4	0.3–0.6	<0.001
Mental disorders (No)	1.0	-	-
Yes	0.4	0.3–0.5	<0.001
Injury and poisoning (No)	1.0	-	-
Yes	1.1	0.6–2.0	0.739
Intentional self-harm
Unintentional self-harm	1.0	-	-
Intentional self-harm	2.1	1.5–2.7	<0.001
More than one injury diagnosis
More than one injury diagnosis	1.0	-	-
One or no injury diagnosis	1.5	1.1–2.0	0.011
Injury diagnosis reported on record
No injury diagnosis reported	1.0	-	-
Injury reported	1.5	0.8–2.7	0.180
Method of Injury
Injury by falling (No)	1.0	-	-
Yes	1.3	0.7–2.6	0.446
Injury by poisoning (No)	1.0	-	-
Yes	0.4	0.1–1.3	0.124
Injury by assault (No)	1.0	-	-
Yes	1.1	0.6–1.8	0.912
Primary expected payer
Self-payer	1.0	-	-
Medicare	0.4	0.3 – 0.6	<0.001
Medicaid	0.3	0.2–0.4	<0.001
Private including Health Maintenance Organization (HMO)	0.5	0.3 – 0.6	<0.001
No charge	0.4	0.2 – 1.0	0.063
Other	0.5	0.4 – 0.8	0.003