83 Multicenter Evaluation of the Use of Nebulized Heparin for Inhalation Injury (HIHI2 Study)

Introduction Inhalation injury (IHI) causes significant morbidity and mortality secondary to local compromise of the respiratory system as well as systemic effects limiting perfusion and oxygenation. Nebulized heparin reduces fibrin cast formation and duration of mechanical ventilation in patients with IHI. To date, no study has compared both dosing strategies of 5,000 and 10,000 units to a matched control group. The objective of this study is to compare heparin 5,000 and 10,000 units to a historical control and determine which dosing strategy improves lung function and decreases mechanical ventilation duration. Methods This multicenter, retrospective, case-control study included adult patients with bronchoscopy-confirmed IHI. Each control patient, matched according to age and percent of total body surface area (TBSA), was matched to a patient who received 5,000 units and a patient who received 10,000 units of nebulized heparin, according to each institution’s inhalation injury protocol. Patients were excluded if they were pregnant, incarcerated, died within 72 hours of admission, terminally weaned for reasons other than burn or IHI, had a documented allergy to heparin or history of heparin-induced thrombocytopenia, history of pulmonary hemorrhage within 3 months, or history of a clinically important bleeding disorder. The primary endpoint of the study was total duration of mechanical ventilation (excluding patients who died or were not extubated). Secondary endpoints included 28-day mortality, ventilator-free days in the first 28 days, difference in lung injury scores, length of hospitalization, incidence of bronchoscopy, incidence of ventilator-associated pneumonia, and rate of bleeding events. Results Thirty-five matched patient trios met inclusion criteria. Groups were well-matched for age (p=0.975) and TBSA (p=0.855). When excluding patients who died or were never extubated, patients who received nebulized heparin, either 5,000 or 10,000 units, had 8–11 less days on the ventilator compared to controls (p=0.001). Mortality ranged from 3–14% overall, and no statistical difference was observed between groups. No major or minor bleeding events related to nebulized heparin were reported. Conclusions Mechanical ventilation days were significantly decreased in patients who received 5,000 or 10,000 units of nebulized heparin. There was no statistically significant difference in mortality between groups, supporting that either 5,000 units or 10,000 units of nebulized heparin should be used in IHI treatment. Applicability of Research to Practice To our knowledge, no previously published studies have simultaneously compared dosing strategies of 5,000 and 10,000 units to a control group. These results support the use of nebulized heparin for IHI to reduce the duration of mechanical ventilation.