The Science Journal of the American Association for Respiratory Care

1998 OPEN FORUM Abstracts

CLINICAL EVALUATION OF A NEW CLOSED LOOP VENTILATION MODE: ADAPTIVE SUPPORTIVE VENTILATION (ASV).

Robert S Campbell RRT, Reynaldo P Sinamban MD, Jay A Johannigman MD, Fred A Luchette MD, Scott B Frame MD, Kenneth Davis Jr. MD, Richard D Branson RRT. University of Cincinnati College of Medicine, Cincinnati, OH 45267-0558.

INTRODUCTION: ASV (Galileo, Hamilton Medical) is a mode of mechanical ventilation (MV) with a closed loop program to determine and adjust ventilator settings with the exception of PEEP and FiO_{2}. ASV is capable of adjusting the number of mandatory breaths, the I:E of mandatory breaths, and the pressure of both mandatory and spontaneous breaths. We compared ventilator parameters and gas exchange during initiation of MV with ASV to physician determined ventilator settings. Methods: Post-operative pts. (n=19) requiring MV due to continued neuromuscular blockade were entered in the study following informed consent from next of kin. Settings ordered by the physician were noted and each pt was placed on those settings or ASV in random sequence. ASV requires input of pt ideal body weight (IBW) and a % Minute Volume to be delivered (100%=100mL/Kg/min). IBW was determined from standardized tables and %MinVol was set to 100%. PEEP and FiO_{2} were determined by the attending staff and kept constant. Arterial blood gases (pH, PaCO_{2}, PaO_{2}, SaO_{2}) and cardiopulmonary variables (f, V_{T}, V_{E}, T_{i}, PIP, P_{aw}, HR, MAP, and VCO_{2}) were measured and recorded after 30 min. on each mode. Data were compared using student's t-test and p < 0.05 was considered significant. Results: Mean IBW was 88.8 Kg. There were no differences in ABGs between ASV and conventional ventilation, respectively (pH = 7.40 ± .07 vs 7.39 ± .06, PaCO_{2} = 37.6 ± 5 vs 38.6 ± 5, PaO_{2} = 100.0 ± 31 vs 106.1 ± 33). V_{D}/V_{T} was lower during ASV (51.3 ± 6 vs 57.4 ± 8%). V_{E} (9.6 ± 2 vs 9.5 ± 2 L/min) and T_{i} (1.5 ± 0.5 vs 1.43 ± 0.3 sec) were similar between ASV and conventional ventilation, respectively. Respiratory rate was higher with ASV (14.4 ± 3 vs 10.1 ± 2 bpm). PIP (25.2 ± 8 vs 31.9 ± 9 cmH_{2}O) and V_{T} (690 ± 121 vs 863 ± 133 mL) were significantly lower with ASV. There were no differences in HR (87 ± 16 vs 89 ± 16), MAP (73 ± 15 vs 72 ± 19), or VCO_{2} (262 ± 48 vs 265 ± 56 ml/min) between ASV and conventional ventilation. V_{T} during ASV was more consistent with "lung protective" strategy (7.8 mL/Kg) than was conventional V_{T} (9.7 mL/Kg). Conclusions: Use of ASV to initiate MV in non-spontaneous breathing pts provides equivalent gas exchange to MV ordered by the physician. MV with ASV is more efficient as evidenced by lower V_{D}/V_{T} values and may be safer as a result of the lower V_{T} and PIP.

The 44th International Respiratory Congress Abstracts-On-Disk®, November 7 - 10, 1998, Atlanta, Georgia.

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