A retrospective analysis of nitric oxide inhalation in patients with severe acute lung injury in Sweden and Norway 1991-1994

BACKGROUND: Patients with severe acute lung injury (ALI) have been treated compassionately on doctors' initiative with inhaled nitric oxide (INO) in Sweden and Norway since 1991. In 1994 the previously used technical grade nitric oxide was replaced by medical grade nitric oxide. METHODS: We have carried out a retrospective data collection on all identified adult patients treated with INO for >4 h during the period 1991-1994 focusing on safety aspects and patient outcome. We used the following exclusion criteria (1) Age <18 years, (2) Simultaneous treatment with extracorporeal removal of CO2 (3) NO inhalation period <4 h, (4) Incomplete or missing patient charts, (5) Use of INO in order to treat pulmonary hypertension following cardiac surgery, with little or no acute lung injury. RESULTS: Inclusion criteria were met by 56 out of 73 identified patients. Mean age was 48+/-19 years and the median duration of INO treatment was 102 h. PaO2/FIO2 ratio at start of treatment was 85 +/- 33 mm Hg with a lung injury score (LIS) of 3.2+/-0.8. The aetiology of the lung injury was pneumonia (n= 27), sepsis (n=12) and trauma (n=8). Survival to hospital discharge was 41% and survival after 180 d was 38%. Three serious adverse events were identified, two from technical failures of the INO delivery device and one withdrawal reaction necessitating slow weaning from INO. No methaemoglobin values >5% were reported during treatment. CONCLUSION: The overall mortality did not differ dramatically from historical controls with high mortality. Only a randomised study may determine whether INO as an adjunct to treatment alters the outcome in severe ALI. One cannot at present advocate the routine use of INO in patients with ALI outside such studies.