ISSN:
1432-1238
Schlagwort(e):
Inspiratory pressure support
;
Synchronized intermittent mandatory ventilation
;
Ventilation/perfusion distribution
;
Weaning
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Medizin
Notizen:
Abstract Since the introduction of synchronized intermittent mandatory ventilation (SIMV) several advantages have been attributed to this ventilatory mode, one of them being a more homogeneous distribution of ventilation and perfusion than during controlled mechanical ventilation (CMV). Up to now no data are available to confirm whether this is true when SIMV is used in combination with inspiratory pressure support (IPS). Therefor, we compared the influence of CMV and SIMV+IPS on the distributions of ventilation and perfusion in 9 patients undergoing weaning from postoperative mechanical ventilation. Continuous distributions of ventilation and perfusion were assessed using the multiple inert gas elimination technique (MIGET). SIMV+IPS did not induce any change in the hemodynamic or oxygenation parameters, in particular CI and PaO2 remained constant. Physiological dead space $$(\dot V_D /\dot V_T )$$ increased, but PaCO2 remained unchanged due to increased minute ventilation (from 9.5±0.9l·min−1 to 11.3±1.2l·min−1). The perfusion distributions remained unaltered; there was no change in $$\dot Q_S /\dot Q_T $$ nor in the perfusion of the low $$\dot V_A /\dot Q$$ lung regions. This result was underscored by the unchanged dispersion of the perfusion distribution (log $$SD\dot Q$$ ). The increased $$\dot V_D /\dot V_T $$ was caused by increased inert gas dead space (from 22.0±9.6 to 26.8±8.7%) which was accompanied by increased ventilation of lung regions with high $$\dot V_A /\dot Q$$ ratios ( $$(10〈 \dot V_A /\dot Q〈 100)$$ ) in 3 patients. These results show that in our group of patients partial removal of CMV together with pressure support assistance of spontaneous ventilation did not induce a clinically significant loss of the efficiency of the breathing pattern. Since the unchanged hemodynamic parameters were accompanied by increased minute ventilation, arterial blood gases did not deteriorate. Hense, SIMV+IPS proved to be useful for weaning from postoperative mechanical ventilation.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF01704716
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