The Science Journal of the American Association for Respiratory Care

1999 OPEN FORUM Abstracts

EVALUATION OF INSPIRATORY RISE TIMES IN NEW GENERATION MECHANICAL VENTILATORS

Sunisa Chatmongkolchart, MD, Purris Williams, BA, RRT, Dean Hess, PhD, RRT, FAARC, Robert M Kacmarek, PhD, RRT, FAARC Anesthesia and Respiratory Care, Harvard Medical School and Massachusetts General Hospital, Boston, Massachusetts.

Rise time during pressure targeted ventilation has been shown to be a factor affecting patient-ventilator synchrony. Both excessive and inadequate rise time may decrease patient-ventilator synchrony. Three different inspiratory rise times (minimum, medium, maximum) were evaluated in 5 new generation mechanical ventilators, (Hamilton Galileo, Siemens 300 A, Nellcor Puritan Bennett 840, Bear 1000, and Drager Evita) during both pressure support (PS) and pressure control (PC) in which PEEP was set at 5 cmH2O and inspiratory pressure at 15 cmH2O. All evaluations were performed on a spontaneous breathing lung model with compliance 50 ml/cmH2O, airway resistance 8.2 cmH2O/L/s, respiratory rate 12 breaths/min, inspiratory time 1.0 second, and peak inspiratory flow 60 L/min. There were some statistically significant differences (p<0.05) between PS and PC, but none were considered clinically important. Therefore we present only pressure support ventilation data (mean ± SD). Minimal differences exist between PS and PC during rise time adjustment. However, differences do exist among ventilators at similar rise time settings and with each ventilator as rise time is adjusted.

PS Galileo Siemens Pb840 Bear1000 Drager
P-T minimum* 8.42 ± 0.10bc 4.16 ± 0.10c 4.59 ± 0.17bc - 6.61 ± 0.09bc
medium* 7.54 ± 0.00ac 3.83 ± 0.20c 3.77 ± 0.17ac 4.78 ± 0.20 6.28 ± 0.09ac
maximum* 5.69 ± 0.34ab 1.91 ± 0.09ab 1.86 ± 0.25ab 4.43 ± 0.20 4.26 ± 0.00ab
T-PTP minimum* 0.92 ± 0.02bc 0.45 ± 0.02bc 0.34 ± 0.01bc - 0.90 ± 0.02bc
medium* 0.70 ± 0.01ac 0.34 ± 0.02ac 0.23 ± 0.01ac 0.38 ± 0.02c 0.77 ± 0.02ac
maximum* 0.37 ± 0.02ab 0.05 ± 0.00ab 0.06 ± 0.01ab 0.23 ± 0.01b 0.14 ± 0.00ab
Area 1% minimum* 0.53 ± 0.01bc 0.50 ± 0.01bc 0.61 ± 0.01bc - 0.20 ± 0.00bc
medium* 0.62 ± 0.00ac 0.64 ± 0.00ac 0.72 ± 0.00ac 0.71 ± 0.00c 0.35 ± 0.00ac
maximum* 0.77 ± 0.01ab 0.79 ± 0.00ab 0.87 ± 0.01ab 0.77 ± 0.02b 0.82 ± 0.01ab

No data available for Bear 1000 at minimum setting. a = p<0.05 VS minimum for specific ventilator, b = p<0.05 VS medium for specific ventilator, c = p<0.05 VS maximum for specific ventilator, * = p<0.05 among ventilators. P-T-inspiratory trigger pressure; T-PTP-trigger pressure time product; Area I%-actual inspiratory area as a percentage of maximum possible inspiratory area.

OF-99-082

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