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Instability of breathing chemical control system, as expressed by intrinsic respiratory system loop gain, and periodic breathing in critically ill patients. Influence of propofol

By Μαρία Κλημαθιανάκη


Background: To investigate Propofol’s effect on breathing stability of brain damage patients, as quantified by the Loop Gain (LG) of the respiratory system (breathing stability increases with decreasing LG). Methods: In 11 stable brain damage patients full polysomnography was performed before, during and after propofol sedation, titrated to achieve stage 2 or slow wave sleep. During each period, patients were ventilated with proportional assist ventilation and the % assist was increased in steps, until either PB occurred or the highest assist (95%) was achieved. The tidal volume amplification factor (VTAF) at the highest assist level reached just before PB occurred was used to calculate LG (LG=1/VTAF). Results: In all but one patients PB was observed with increasing the % assist. With propofol the assist level at which PB occurred (73±19%) was significantly higher, than that before (43±35%) and after propofol sedation (49±29%). As a result, with propofol LG (0.49±0.2) was significantly lower than that before (0.74±0.2) and after propofol sedation (0.69±0.2) (p< 0.05). Conclusions: 1) Patients with brain damage are at risk of unstable breathing, as indicated by a high and reproducible LG, and 2) propofol infusion results in a significant decrease in LG, suggesting that its overall effect on control of breathing is stabilizing

Topics: Περιοδική αναπνοή, Αναλογικά υποβοηθούμενος μηχανικός αερισμός, Έλεγχος αναπνοής, Εγκεφαλική βλάβη, Periodic breathing, Proportional assist ventilation, Brain injury, Control of breathing
Publisher: University of Crete (UOC)
Year: 2010
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