Zusammenfassung:
Einleitung: Zur Verbesserung von Perfusion und Sauerstoffversorgung unter Reanimation wurde das neue kompressionssynchrone, druckkontrollierte Beatmungsverfahren Chest Compression Synchronized Ventilation (CCSV) entwickelt und im Tiermodell untersucht. Messwerte dieser Studie dienten der vorliegenden Arbeit als Grundlagen. In ihrem Rahmen sollte festgestellt werden, ob während einer kardiopulmonalen Reanimation unter CCSV gegenüber dem Standardverfahren (Intermittent Positive Pressure Ventilation, IPPV) Verbesserungen des Sauerstoffangebotes (DO2), der Sauerstoffaufnahme (VO2) oder damit verbundener Parameter zu erreichen sind.
Material und Methoden: Nach erfolgter Genehmigung durch das zuständige Regierungspräsidium wurden 44 Schweine unter fortlaufender Narkose und Analgesie endotracheal intubiert und mit entsprechenden Messapparaturen versehen. Nach iatrogener Einleitung eines Kammerflimmerns (t = 0 min) erfolgte eine Randomisierung in CCSV (Tinsp 265 ms, Pinsp 60 mbar, steile Rampe) und IPPV (AF 10/min, VT 7 ml/kgKG, Pmax 45 mbar, I:E 1:1,5). Nach drei Minuten unbehandelten Kammerflimmerns wurde die jeweilige Beatmung und parallel eine Thoraxkompression mittels LUCAS™ begonnen (t = 3 min). Arterielle und venöse Blutentnahmen sowie HZV-Messungen fanden zu den Zeitpunkten t = 4 min, 8 min, 12 min, 16 min, 20 min und 24 min statt. Rhythmusanalysen und – sofern indiziert – Defibrillationen wurden zu den Zeitpunkten t = 13 min, 15 min, 17 min, 19 min, 21 min und 23 min durchgeführt. Tiere mit ROSC wurden in eine gesonderte Nachbetreuung übernommen. Medikamentenapplikationen fanden zu den Zeitpunkten t = 7 min, 14 min, 18 min, 22 min (Adrenalin 1 mg i.v.) und t = 11 min (Vasopressin 0,8 IU/kgKG i.v.) statt. Aus den resultierenden Messwerten wurden CaO2, DO2, DO2I, CvO2, avDO2, VO2, VO2I und O2ER berechnet und deren Veränderungen unter Reanimation gegenüber den Ausgangswerten bis zum Zeitpunkt t = 12 min bestimmt. Mittels Whitney-U-Test erfolgte ein Vergleich der CCSV- und IPPV-Tiere, sowohl innerhalb der Gesamtpopulation (GP) als auch gesondert für Tiere mit ROSC nach der ersten Defibrillation (Primary Responder, PR) und solche ohne ROSC nach der ersten Defibrillation (Primary Non-Responder, PNR). Den Schwerpunkt der Betrachtung und Diskussion stellten GP und PR dar. Anschließend wurden außerdem PR und PNR gegenübergestellt und im Hinblick auf mögliche Charakteristika verglichen. Die Darstellung der Ergebnisse erfolgte anhand des Medians (Q0,25/Q0,75), statistische Signifikanz wurde bei p < 0,05 angenommen.
Ergebnisse: ROSC konnte bei 15 Tieren unter CCSV und 20 Tieren unter IPPV erzielt werden (p = ,065), der durchschnittliche Zeitpunkt sowie die Anzahl der PR je Verfahren waren identisch (CCSV vs. IPPV): ROSC t [min]: 13 (13/15) vs. 13 (13/16,5), p = ,542; PR pro Gruppe: 11 vs. 11, p = 1. Innerhalb der GP konnten unter anderem die folgenden Differenzwerte ermittelt werden (CCSV vs. IPPV): DO2 [ml/min]: -297,9 (-404,71/-241,56) vs. -211,11 (-324,69/-135,82), p = ,052; VO2 [ml/min]: 4,55 (-55,53/46,29) vs. 8,62 (-46,4/82,73), p = ,528; CaO2 [ml/l]: 27,02 (14,97/42,57) vs. 14,76 (-10,18/23,87), p = ,019; HZV [l/min]: -2,4 (-3,25/-2,02) vs. -1,58 (-2,73/-1,26), p = 0,53. Weitere Unterschiede nicht signifikant. Die Auswertung der PR ergab folgendes (CCSV vs. IPPV): DO2 [ml/min]: -256,44 (-387,47/101,93) vs. -185,28 (-284,57/-138,44), p = ,3; VO2 [ml/min]: 30,16 (4,55/240,41) vs. 12,82 (-57,03/66,02), p = ,519; CaO2 [ml/l]: 32,78 (24,25/45,82) vs. 15,68 (4,91/23,16), p = ,007; avDO2 [ml/l]: 76,09 (70,92/82,7) vs. 62,36 (51,65/72,06), p = ,005; HZV [l/min]: -2,4 (-3,3/-0,43) vs. -1,5 (-2,17/-1,27), p = 0,243. Alle weiteren Unterschiede nicht signifikant.
Diskussion: CCSV bietet insbesondere durch eine signifikante Verbesserung von CaO2 die Voraussetzung, Sauerstoffangebot und -aufnahme unter Reanimation nachhaltig zu optimieren. Nach wie vor stellen jedoch deutliche Absenkungen des Herzzeitvolumens, wie sie auch in vergleichbaren Studien im Reanimationsverlauf zu beobachten sind, eine entscheidende Limitation dar. Der Fokus zukünftiger Forschungsanstrengungen zur Wiederbelebung sollte daher insbesondere auf einer Verbesserung des HZV unter Reanimation liegen. Im Hinblick auf CCSV sind außerdem weitere Untersuchungen, beispielsweise über den Einsatz bei für längere Zeit unbehandeltem Herzkreislaufstillstand sowie in Kombination mit vorhergehender Reanimation unter alternierender Thoraxkompression und Beatmung im Verhältnis von 30:2, notwendig.
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