Klinische Anwendung extrakorporaler Membran-Oxygenierung (ECMO) beim Neugeborenen mit respiratorischer Insuffizienz

Zusammenfassung

ECMO ist eine therapeutische Alternative für die Behandlung der respiratorischen Insuffizienz des Neugeborenen, die mit herkömmlicher Beatmungstechnik nicht zu behandeln ist. Unsere ECMO-Technik entspricht der etwas modifizierten, von Bartlett beschriebenen veno-arteriellen Perfusion über die rechtsseitige Vena jugularis interna und Arteria carotis communis. Die extrakorporale Zirkulation muß meist für 3 bis 6 Tage mit Flußraten von 80-120 ml/kg/min ausgeführt werden. Die Einschätzung des Mortalitätsrisikos erfolgt durch Bestimmung des alveolo-arteriellen Sauerstoffgradienten (D [Aa] O₂). Danach kommen zur Zeit bei uns nur Kinder über 1800 g und einer Mortalitätswahrscheinlichkeit über 80% für ECMO in Frage. Eine Senkung der Mortalität auf 30-50% ist zu erwarten.

ECMO wird bei Neugeborenen im wesentlichen bei folgenden Krankheitsbildern angewandt: Angeborene Zwerchfellhernie, primäre pulmonale Hypertension (PPHN) und Mekonium- aspirationssyndrom. Die Langzeitergebnisse scheinen aufgrund geringerer Traumatisierung durch hohe Beatmungsdrukke und Vermeidung prolongierter Hypoxie besser zu sein. Es werden die Erfahrungen aus der Vorbereitungsphase zur Etablierung eines ECMO-Teams sowie zur ersten erfolgreichen klinischen Anwendung beschrieben.

Summary

ECMO is a therapeutic alternative for newboms with respiratory insufficiency unmanageable by artificial Ventilation. A modified heart-lung machine well suited for long-term application is used both to support life and to take over organ function, allowing this organ to rest and to recover. The ECMO-technique as practised in our group is equivalent to the venousarterial bypass initiated by the Barfletf-team.

Venous blood is drained from the right atrium via the right internal jugular vein. After passage through a membrane oxygenator and a heat exchanger it is returned in an arterialized State to the ascending aorta via the right carotid artery.

Canulation is followed by systemic heparization. With a roller pump extracorporeal circulation is installed for 3-6 days with flow-rates of 80-120 ml/kg/min. The Operation is performed under local anesthesia in the neonatal intensive care unit.

The typical course of ECMO is stabilization for the first 24-48 hours on high bypass flow rates keeping paO₂ at 50-60 mmHg with minimal Ventilator settings (Pmax 20 mmHg, FiO₂ 0.3-0.4). Bypass flow rates can be reduced for the next 24 h and the patient is taken off and decanulated while on similar Ventilator settings. Because of systemic heparinization intracranial bleeding is the main complication for a newborn child on ECMO. The incidence is about 10%. Premature infants per se have a high risk of major intracranial bleeding without ECMO. Therefore contraindications are infants under 35-weeks gestation, and a hemorrhage diagnosed by ultrasound prior to ECMO. Prediction of mortality is estimated by the alveoloarterial oxygen gradient (D [Aa] O₂). We could demonstrate that mean values for the first 6 hours of life are able to give a very precise prognosis of mortality.

In our group currently only newboms with more than 1 800 g birth weight and mortality risk of 80-100% are selected for ECMO.

Lowering of the mortality rate to 30-50% can be expected in moribund patients, with increased experience and improved indication to 20%.

ECMO is successfully used in patients with congenital diaphragmatic hernia, primary pulmonary hypertension (PPHN) and meconium aspiration Syndrome. That means respiratory failure in the newborn is usually caused by immaturity, and abnormalities of the airways and pulmonary circulation, rather than parenchymal disease as in the adult.

The capacity for lung recovery especially in neonates is excellent provided the child survives.

Additionally to life support long-term results are better since lung damage following high pressure Ventilation and elevated oxygen concentration or prolonged hypoxia is reduced.

Our experience with the preparatory phase in establishing an ECMO-team as well as preliminary results of our first clinical application are described.

Key words

Extracorporeal membrane oxygenation (ECMO) - Neonatal respiratory failure - Hypoxia