The Science Journal of the American Association for Respiratory Care

1995 OPEN FORUM Abstracts

PRESSURIZATION RATE REGULATION MAY REDUCE INSPIRATORY EFFORT DURING PRESSURE SUPPORT VENTILATION (an 'in vitro' study).

Massimo Croci MD, Paolo Pelosi MD, Lucia Negroni MD, Alba Norsa MD, Gabriella Toniolo MD, Patrizia Andreoni MD, Luciano Gattinoni MD. Inst. of Anesthesia and Intensive Care, University of Milan, Ospedale Maggiore IRCCS, Milan, Italy.

Recent mechanical ventilators allow to adjust the pressurization rate (PR) during pressure support ventilation (PSV). The aim of this study was to evaluate "in vitro" the influence of PR regulation on the inspiratory effort during PSV. METHODS We studied a new mechanical ventilator (Bear 1000) set with PEEP 10 cm H_2O and pressure support at 10 cm H_2O at three different PR values (arbitrary units): low (-5), medium (0) and high (+5). Tests were performed connetting this ventilator to an active lung simulator (1) set to mimic low (VT/Ti = 0.45 1 s^{-1}) and high (VT/Ti 0.9 1 s^{-1}) inspiratory drive. We measured the pressure time product before (PTP1) and after flow delivery (PTP2) (2). RESULTS Results are presented as mean ± S.D.

PRLOW MEDIUMHIGH

PTP1 (cm H_2O*s)

Low drive 0.04±0.004 0.04±0.002 0.04±0.004

High drive0.02±0.005 0.04±0.007 0.03±0.003

PTP2 (cm H_2O*s)

Low drive 1.39±0.08 0.39±0.05 0.21±0.04*

High drive3.29±0.14 # 0.49±0.04 # 0.13±0.05 #*

ANOVA: * pɘ.01 between different PR; # pɘ.05

high vs low inspiratory drive.

CONCLUSION During PSV, PR does not influence inspiratory effort to trigger the ventilator. After inspiratory flow delivery, PR regulation may actually reduce inspiratory effort, particularly when inspiratory drive is high. We may conclude that PR regulation is an important tool to improve patientventilator synchrony. REFERENCE 1) Intensive Care Med 1988, 14:60-3 2) Respir Care 1992, 37:1056-69

OF-95-083

You are here: RCJournal.com » Past OPEN FORUM Abstracts » 1995 Abstracts » PRESSURIZATION RATE REGULATION MAY REDUCE INSPIRATORY EFFORT DURING PRESSURE SUPPORT VENTILATION (an 'in vitro' study).