The Science Journal of the American Association for Respiratory Care

1998 OPEN FORUM Abstracts

CAN THERAPISTS OPTIMIZE VENTILATION BASED ON GRAPHIC ANALYSIS

Steven Slaughter, RRT, Timothy Myers, RRT, Robert L. Chatburn, RRT University Hospitals of Cleveland, Ohio

The purpose of this study was to determine if experienced ICU therapists could (1) identify basic ventilator modes based only on pressure, volume and flow waveforms, (2) recognize common problems using waveforms, and (3) optimize ventilator settings on a simulated patient based only on the output of a bedside mechanics monitor. We also hypothesized that therapists might perform better with the ventilator set to volume control mode versus pressure control. Methods: All adult and pediatric ICU therapists were eligible to enter the study. In Phase I, therapists were asked to identify 8 different modes of ventilation. In Phase II, therapists were shown waveforms of common problems. In Phase III, therapists were asked to optimize settings in volume and pressure controlled continuous mandatory ventilation (CMV) with the ventilator (NPB 7200) connected to a lung model (modified IngMar Medical). Therapists could only see waveforms, loops, tidal volume, minute ventilation, resistance, and compliance. The model simulated both upper and lower inflections points on the volume/pressure curve. The only clinical data given were diagnosis (ARDS) and baseline ABGs. Waveforms (Phase I & II) and graphic displays (Phase III) were generated with a Novametrix CO_{2}SMO_{+} connected to a computer. Data for volume vs pressure control were compared with Wilcoxon Signed Rank tests with significance at p < =0.05. Results: Twenty six therapists entered the study. Of these, only 3 did not complete Phase III. All had ICU experience (range 2-21 years, median 8) with access to graphic monitors (NPB 7200, BICORE, or Ventrack). No therapist got a perfect score on all three phases. A passing score was defined as 75% or more; 58% of therapists passed Phase I, 35% Phase II, and 9% Phase III. There were no differences in distributions of scores between volume and pressure control modes. Test results are shown below as a percentage of therapists giving correct responses, grouped by mode or clinical problem:

Phase I CMV SIMV SIMV + PS PS CPAP

Volume Control: 69% 73% 58% -- --

Pressure Control: 77% 54% 46% 69% 73%

Phase II Water in Airway Leak Obstruction autoPEEP

Tubing

50% 46% 58% 46%

Phase III. Optimizing the ventilator was defined as (1) decreasing tidal volume, (2) maintaining the same minute ventilation, (3) no change of I:E, (4) increasing rate, (5) increasing PEEP. Results below show patterns of correct responses:

5 of 5 4 of 5 3 of 5 2 of 5

Volume Control: 5% 4% 39% 26%

Pressure Control: 0% 9% 39% 26%

1 of 5 0 of 5

Volume Control: 26% 0%

Pressure Control: 26% 0%

CONCLUSION: Based on these data, therapists can recognize basic ventilator patterns, but get confused with complex breath patterns. They seem unable to recognize common problems or to optimize ventilator settings, despite using the equipment on a daily basis. These baseline data will be used in a process improvement educational program.

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

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