Schwierige Entwöhnung vom Respirator: Beatmung und weitere Strategien

Zusammenfassung

Das ventilatorische Versagen infolge Überlastung und/oder reduzierter Kapazität der Atempumpe ist die häufigste Ursache für die erfolglose Entwöhnung vom Respirator (Weaning) und damit für die Notwendigkeit der invasiven Langzeitbeatmung (LZB). Dabei steht die chronisch obstruktive Lungenerkrankung (COPD) im Vordergrund. Der wichtigste klinische Parameter für die erschöpfte Atemmuskulatur ist die schnelle flache Atmung („rapid shallow breathing”). Weitere Faktoren, die im Weaning-Prozess den Erfolg negativ beeinflussen können, sind neuromuskuläre Erkrankungen, Herzinsuffizienz, die inadäquate tiefe und lange Sedierung, Mikro- bzw. Makroaspiration, Mangelernährung, Anämie und Adipositas per magna. Protokollbasierte Entwöhnungsstrategien und die Verwendung von so genannten „Weaning-Prädiktoren” sind hilfreich. Dennoch ist der erfahrene Intensivmediziner im Weaning nicht zu ersetzen. Das Ziel im Weaning nach LZB heißt „Rekonditionierung der Atemmuskulatur”. Alle therapeutischen Maßnahmen sollten darauf abzielen, durch entlastende Strategien eine Erholung der überlasteten Atemmuskulatur zu erreichen. Assistierte Beatmungsformen sind im Weaning weit verbreitet. Eine ausreichende Entlastung der erschöpften Atemmuskulatur lässt sich damit sehr häufig nicht erreichen, da die inspiratorische Atemarbeit signifikant erhöht bleibt. Demgegenüber führt eine individuell adaptierte, kontrollierte Beatmung (mit Druck- oder Volumenvorgabe), die auch bei klarem Bewusstsein des Patienten möglich ist, zur maximalen Entlastung der Atemmuskulatur und deren Erholung. Weitere entlastende Maßnahmen sind die Korrektur einer Anämie, die pharmakologische Reduktion des Atemantriebes (z. B. durch Morphinpräparate), die Sauerstoffgabe während der Spontanatmung, das Aufrichten des Oberkörpers vor allem bei Adipositas und die Überführung des katabolen in den anabolen Ernährungszustand. Insbesondere bei Patienten mit broncho-pulmonalen Vorerkrankungen (z. B. COPD) hat die nichtinvasive Beatmung (NIV) während der Entwöhnung von der invasiven Beatmung, aber auch in der Postextubationsphase einen hohen Stellenwert. NIV sollte im Weaning-Prozess unter engmaschigem Monitoring der Vitalfunktionen, bei vorhandener Kooperation des Patienten und mit Wissen um die Grenzen der Methode durchgeführt werden. Sterben am Respirator in der Endphase eines chronischen Krankheitsverlaufes bleibt eine große Herausforderung für alle Beteiligten. Gelingt ein erfolgreiches „Weaning in der Terminalphase”, dann ist es manchem Patienten doch noch möglich, den letzten Lebensabschnitt außerhalb einer Intensivstation zu verbringen.

Abstract

Respiratory failure as a result of overload and/or reduced capacity of the respiratory muscles is the most common cause of unsuccessful weaning and the need for long term mechanical ventilation. Chronic obstructive pulmonary disease (COPD) is the most common underlying cause leading into long term mechanical ventilation. The most important clinical parameter for fatigue of the respiratory muscles is the rapid shallow breathing index. Other essential factors which impact weaning failure, are the underlying diseases (e. g. neuromuscular disease or heart failure), micro- and macro aspiration, malnutrition, anemia and obesity. A protocol based strategy to discontinue mechanical ventilation and the use of weaning predictors are helpful. Nonetheless the experienced physician is irreplacable in the weaning process. Reconditioning of the respiratory muscles is the main focus during weaning after long term mechanical ventilation and all therapeutic measures should be targeted to unload the fatiguing respiratory muscles. With the widely used assisted ventilation modes, the inspiratory work of breathing is still significantly increased. Only controlled mechanical ventilation (pressure- or volume controlled), which may also be applied to unsedated patients when individually adapted, offers the best possible relief and recovery of the respiratory muscles. Additional strategies, such as the balancing of anemia, reduction of the respiratory drive with i. e. morphine derivates, oxygen therapy during spontaneous-breathing trials and supine position for patients with obesity contribute to the recovery. Particularly patients with chronic lung diseases with hypercapnia benefit from the use of non invasive ventilation (NIV) after extubation to prevent postextubation failure and even after tracheostomy. However, NIV should only be applied under close monitoring and in cooperative patients, always considering the limits of the method. Dying under mechanical ventilation in the end stage illness is still a challenge for all involved persons. In the end stage of their disease for some patients it is possible to discontinue mechanical ventilation so they can spend the last period of their lives on a normal ward or even at home.

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