Substance use and inhalation injury in adult burn patients: retrospective study of the impact on outcomes

BACKGROUND: Substance use, alcohol use, and smoking use have all been associated with burn injury. Few studies have investigated associations with substances, alcohol, smoking, inhalational only burns, and patient outcomes. The purpose of the study was to identify risk factors for pulmonary failure in patients suffering inhalation injury, focusing on the impact of substance, alcohol, and cigarette use. METHODS: This is a single-center retrospective analysis of 115 patients admitted to the Johns Hopkins Bayview Burn Center with inhalational injury from January 1, 2010, through September 30, 2018. Patients were excluded if they were under the age of 18 years or had burn involvement of the skin > 5%. Primary outcome variables measured were if patients were intubated, length of total time intubated, substance use, alcohol use, and smoking use. Secondary outcome variables measured were types of substances used (amphetamines, barbiturates, benzodiazepines, cannabinoids, cocaine, methadone, codeine/morphine), total number of substances used, intensive care unit (ICU) length of stay (LOS), hospital LOS, secondary complications, and patient mortality. Analysis was performed with Fisher’s exact test and the Mann-Whitney U test. A sub-group analysis for each substance, alcohol, smoking, and control sub-group was compared to its respective sub-group without substance, alcohol, smoking, and control within the no intubation and intubation group. A sub-group analysis of substance use, alcohol use, smoking use, and control was further analyzed with binomial logistic regression within the intubation group. RESULTS: Following inhalation injury, 50/115 (43%) patients required intubation. Forty-two of the 50 (84%) patients intubated had substance use (p < 0.001). Thirty-one of the 50 (62%) patients intubated had history of smoking (p = 0.038). Among the specific substances used, 26/50 (52%) patients intubated were using benzodiazepines (p < 0.001) and 7/50 (14%) patients were using cocaine (p = 0.022). The lengths of intubation, ICU LOS, and hospital LOS with no substance use were shorter than with substance use (p < 0.001). Following the adjusted sub-group analysis, patients with substance use (odds ratio (OR) 6.4, 95% confidence interval (CI) [2.5–16.3]; p < 0.001) and smoking use (OR 2.5, 95% CI [1.2–5.1]; p = 0.013) were more likely to be intubated on admission than those without substance or smoking use. CONCLUSIONS: In patients admitted with an inhalational injury with less than or equal to 5% external burns, the presence of a substance and smoking use on admission provides a further risk of intubation and respiratory compromise. Substance use on admission poses a greater risk of longer intubation, ICU LOS, and hospital LOS. A higher potential for substance use should be suspected in this patient population with prompt treatment.