Interhospital ground transportation of severe acute respiratory distress syndrome patients on extracorporeal membrane oxygenation: Monza's experience

Introduction

Severe acute respiratory distress syndrome (ARDS) patient transportation is an extremely high-risk procedure. We report our experience in transferring these patients to our centre while on extracorporeal membrane oxygenation (ECMO).

Methods

After telephone referral and bed availability confirmation, patients matching entry criteria for ECMO are evaluated for transportation to our centre. A skilled crew consisting of two expert plus one training physician, one expert plus one training ICU nurse and one ECMO specialist reaches the referral hospital for re-evaluation. If eligible, cannulation, ECLS circuit set up and ECLS start are accomplished. Ground transport is performed with a specially equipped ambulance, endowing enlarged oxygen, fuel and energy supplies. The ambulance is loaded with all of the items required for cannulation and ECMO circuit set up, additional oxygen and a nitric oxide tank. Entry criteria are: potentially reversible respiratory failure, Murray Score ≥3 or respiratory acidosis with pH <7.2, no intracranial bleeding and absolute contraindication to heparinization.

Results

Between 2004 and 2009 our crew evaluated for transfer on ECMO 15 ARDS patients (10 males), age 38 ± 15 years, BMI 28 ± 7, APACHE II score 26 ± 9, SOFA score 9 ± 4, Oxygenation Index 39 ± 17. The average distance was 133 ± 124 km. Two patients improved after NO trial and were transferred without ECMO. All of the other patients underwent venovenous ECMO: 11 with cannulation of femoral veins, one femoral-jugular veins and one with a DL cannula in the jugular vein. ECMO settings were (mean ± SD) BF 2.9 ± 0.8, GF 3.6 ± 1.6, GF FiO₂ 1. Data have been recorded 30 minutes before and 1 hour after ECLS began: vv-ECMO granted a better clearance of pCO₂ (75 ± 20.5 vs 49.7 ± 7.9 mmHg, P < 0.01), thus improving the pH (7.279 ± 0.10 vs 7.41 ± 0.06, P < 0.01) and mean pulmonary arterial pressure (41 ± 11 vs 31 ± 5 mmHg, P < 0.05) and allowing a reduction in respiratory rate (28 ± 11 vs 9 ± 4, P < 0.01), minute ventilation (10.2 ± 4.6 vs 3.3 ± 1.7 l/min, P < 0.01) and mean airway pressure (26 ± 6 vs 22 ± 5 cmH₂O, P < 0.01). Arterial pO₂, mean blood pressure and heart rate did not show significant variations. After ECMO began, vasoconstrictor therapy (being administered to five patients) was quickly tapered. Neither clinical nor technical major complications were reported.

Conclusions

ECMO employment at referral centers enabled longdistance, high-risk ground transportation.