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- Title
Respiratory load compensation during mechanical ventilation--proportional assist ventilation with load-adjustable gain factors versus pressure support.
- Authors
Kondili, Eumorfia; Prinianakis, George; Alexopoulou, Christina; Vakouti, Eleftheria; Klimathianaki, Maria; Georgopoulos, Dimitris
- Abstract
<bold>Rationale: </bold>In mechanically ventilated patients respiratory system impedance may vary from time to time, resulting, with pressure modalities of ventilator support, in changes in the level of assistance. Recently, implementation of a closed-loop adjustment to continuously adapt the level of assistance to changes in respiratory mechanics has been designed to operate with proportional assist ventilation (PAV+).<bold>Objectives: </bold>The aim of this study was to assess, in critically ill patients, the short-term steady-state response of respiratory motor output to added mechanical respiratory load during PAV+ and during pressure support (PS).<bold>Patients and Interventions: </bold>In 10 patients respiratory workload was increased and the pattern of respiratory load compensation was examined during both modes of support.<bold>Measurements and Results: </bold>Airway and transdiaphragmatic pressures, volume and flow were measured breath by breath. Without load, both modes provided an equal support as indicated by a similar pressure-time product of the diaphragm per breath, per minute and per litre of ventilation. With load, these values were significantly lower (p<0.05) with PAV+ than those with PS (5.1+/-3.7 vs 6.1+/-3.4 cmH2O.s, 120.9+/-77.6 vs 165.6+/-77.5 cmH2O.s/min, and 18.7+/-15.1 vs 24.4+/-16.4 cmH2O.s/l, respectively). Contrary to PS, with PAV+ the ratio of tidal volume (VT) to pressure-time product of the diaphragm per breath (an index of neuroventilatory coupling) remained relatively independent of load. With PAV+ the magnitude of load-induced VT reduction and breathing frequency increase was significantly smaller than that during PS.<bold>Conclusion: </bold>In critically ill patients the short-term respiratory load compensation is more efficient during proportional assist ventilation with adjustable gain factors than during pressure support.
- Subjects
GREECE; ARTIFICIAL respiration; CRITICALLY ill; AIRWAY (Anatomy); RESPIRATORY organs; CRITICAL care medicine; RESPIRATORY muscle physiology; INTENSIVE care units; RESPIRATION
- Publication
Intensive Care Medicine, 2006, Vol 32, Issue 5, p692
- ISSN
0342-4642
- Publication type
journal article
- DOI
10.1007/s00134-006-0110-0