Clinical evaluation of a computer-controlled pressure support mode.
We have designed a computerized system providing closed-loop control of the level of pressure support ventilation (PSV). The system sets itself at the lowest level of PSV that maintains respiratory rate (RR), tidal volume (VT), and end-tidal CO(2) pressure (PET(CO(2))) within predetermined ranges defining acceptable ventilation (i.e., 12 < RR < 28 cycles/min, VT > 300 ml [> 250 if weight < 55 kg], and PET(CO(2)) < 55 mm Hg [< 65 mm Hg if chronic CO(2) retention]). Ten patients received computer-controlled (automatic) PSV and physician-controlled (standard) PSV, in random order, during 24 h for each mode. An estimation of occlusion pressure (P(0.1)) was recorded continuously. The average time spent with acceptable ventilation as previously defined was 66 +/- 24% of the total ventilation time with standard PSV versus 93 +/- 8% with automatic PSV (p < 0.05), whereas the level of PSV was similar during the two periods (17 +/- 4 cm H(2)O versus 19 +/- 6 cm H(2)O). The time spent with an estimated P(0.1) above 4 cm H(2)O was 34 +/- 35% of the standard PSV time versus only 11 +/- 17% of the automatic PSV time (p < 0.01). Automatic PSV increased the time spent within desired ventilation parameter ranges and apparently reduced periods of excessive workload.
Dojat
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Institut National de la Santé et de la Recherche Médicale (INSERM) U 492, Département de Physiologie, and Service de Réanimation Médicale, Hôpital Henri Mondor, AP-HP, Université Paris 12, Créteil, France.
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Touchard
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Lemaire
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Brochard
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D000368:Aged; D003201:Computers; D005260:Female; D006801:Humans; D008297:Male; D008991:Monitoring, Physiologic; D012121:Respiration, Artificial / Q000379:methods*; D012131:Respiratory Insufficiency / Q000628:therapy; D015300:Ventilator Weaning; D012122:Ventilators, Mechanical