A NOVEL GAS-EXCHANGE-AREA-ADJUSTABLE OXYGENATOR FOR EXTREMELY PRETERM INFANTS

Objectives: Every year, 600,000 infants worldwide are born extremely prematurely (EP). The lungs of these smallest patients are still underdeveloped, so conventional mechanical ventilation can cause severe damage. As an alternative treatment, extracorporeal blood oxygenation (ECMO) functioning as an "artificial placenta" is expected to allow sufficient maturation of the lungs. However, long-term use in these fast-growing patients requires increasing gas exchange performance, which would necessitate device changes with major risks to the patient. Therefore, we propose a new type of "growing" oxygenator. Methods: We developed a gas-exchange-area-adjustable oxygenator that operates at two different sizes without changing the device nor increasing the flow resistance. It consists of two concentric oxygenator cavities, each equal in volume. When only the outer cavity is connected, the oxygenator provides the gas exchange area required by an EP infant at 24 weeks of gestational age (GA) with blood flow rates V̇blood of 50 ml/min – 125 ml/min. As the child grows, the inner cavity can be added by rotation. Together, both cavities cover the needs of an EP infant at 26–28 weeks of GA with V̇blood above 125 ml/min. We performed gas-transfer measurements according to ISO 7199 to verify our novel design. Results: Starting at V̇blood=50 ml/min, gas transfer performance increased until V̇blood=100 ml/min was reached. From here, a drop in performance was observed. Switching on the second chamber at a flow rate of V̇blood=125 mL/min yielded an improvement in gas transfer performance of about 50%. Conclusions: Our novel gas-exchange-area-adjustable oxygenator design proved effective in improving gas transfer performance at increasing blood flow rates. A first milestone was set for the oxygenation of growing EP infants while avoiding the risks associated with a device change.