Objective: To study a cohort of patients treated at the same institution and to compare that patient population with that of a previous report documenting the comorbidity of inhalation injury and pneumonia. Specifically, we wanted to determine whether there had been an improvement in survival of patients suffering inhalation injury.
Design: A retrospective review.
Setting: The US Army Institute of Surgical Research, Ft Sam Houston, Tex, a 40-bed burn intensive care referral unit.
Subjects: One thousand two hundred fifty-six thermally injured patients treated between January 1985 and December 1990.
Main outcome measure: A comparison of pneumonia frequency and ultimate survival of the current cohort of patients as compared with a previously generated stepwise logistic analysis predicting mortality on the basis of 1980 to 1984 patient data.
Results: Of 1256 burned patients admitted between 1985 and 1990, there were 330 identified as having inhalation injury. These patients were older (35.0 vs 26.6 years) and had more extensive burns (41.1% vs 18.3%) and a higher mortality (29.4% vs 5.0%) than did the patients without inhalation injury. When compared with a mortality predictor generated from 1980 through 1984 patient data, patients in the most recent period had a lower mortality than predicted (29.4% vs 41.4%). Patients with less severe injury (positive xenon scan, negative results of bronchoscopy; n = 85), although having a similar incidence of pneumonia (13.1% vs 19.5%) as the same group from 1980 through 1984, accounted for the most improvement in survival. The 3.6% mortality was significantly less than the predicted rate of 15.7%. Patients with positive results of bronchoscopy (n = 245) also showed some improvement in outcome from that predicted (38.3% vs 50.2%) despite no change in the rate of pneumonia (46.9% vs 48.5%). Further improvement in survival was realized in those patients supported with high-frequency ventilation. Although their age (33.9 vs 36.3 years), burn size (46.0% vs 45.5%), and duration of intubation (16.8 vs 15.1 days) were similar to those of conventionally treated patients, mortality was significantly less than predicted (16.4% vs 40.9%) and less than that in patients treated with conventional ventilation (16.4% vs 42.7%).
Conclusions: The improvement in survival of patients with inhalation injury represents the aggregate effects of the general improvement and outcome of all burned patients, the prevention of pneumonia by high-frequency ventilation, and the reduced mortality from the pneumonias that did occur.