High frequency oscillation, extracorporeal membrane oxygenation and pumpless arteriovenous lung assist in the management of severe ARDS.

BACKGROUND: The protective lung strategy for severe ARDS, has markedly decreased the associated morbidity and mortality. Sometimes, even the best instrumentation and therapeutic strategy may be insufficient, and extracorporeal gas exchange support is necessary. We describe a desperate case of ARDS, in which various modes of ventilation, combined with vigorous extracorporeal support, resulted in a successful outcome.

CASE REPORT: A 35-year-old man, a heavy smoker, was admitted to the hospital because of lobar pneumonia. Despite wide spectrum antimicrobial therapy, he developed ARDS and was placed on a ventilator. Standard ventilation was ineffective and veno-venous ECMO was instituted. The extravascular lung water index (EVLWI) was extremely high (over 30 mL kg-1) and signs of a hyperdynamic circulation (CI 6.1 L m-2 min-1) were observed. Modification of the inotropic support and continuous infusion of furosemide resulted in normalisation of the hydration status, and over a week of ECMO therapy, the patient's general condition improved to the stage that he was scheduled to be weaned from extracorporeal treatment. On the 7th day however, he suddenly deteriorated. A lung CT-scan revealed bilateral pneumothoraces and diffuse pulmonary embolism. Three thoracic drains were inserted, but unfortunately, the drainage was complicated by massive bleeding and a subsequent thoracotomy. Two days later, a gastrointestinal haemorrhage occurred. Heparin dosage was reduced, and ECMO was discontinued and replaced with HFOV. This resulted in adequate oxygenation, however because of ineffective CO2 elimination, pumpless arteriovenous extracorporeal lung assist (PECLA) was instituted, allowing conventional ventilation to be resumed after 8 days. The further clinical course was complicated by persistent bilateral pneumothoraces, pleural effusion and Pseudomonas nosocomial infection. The man eventually recovered after 54 days in the ICU, and was transferred to a rehabilitation department.

DISCUSSION AND CONCLUSION: ECMO has been recommended for severe ARDS since it avoids overdistension of the lungs and the use of high oxygen concentrations. Early institution of ECMO decreases mortality and morbidity in rapidly progressing ARDS. In the described case, ECMO was probably started too late, after volutrauma has already occurred. A combination of HFOV and PECLA may be recommended in selected cases, in which CO2 retention poses a serious problem.