The Science Journal of the American Association for Respiratory Care

1996 OPEN FORUM Abstracts

Five Things I Learned This Year About Using the Newest Generation of ICU Ventilators

Richard D. Branson, RRT Sunday, November 3, 1996

Microprocessor ventilators provide the clinician with a never ending array of ventilatory options and monitoring capabilities. Despite this wealth of technology and information, the skilled practitioner still remains the most important machine at the bedside. With that in mind, there are several differences in ventilator function which practitioners should now. While it is impossible for every practitioner to know the nuances of every ventilator, the most frequently used ventilator should be known "inside and out."

Five things I learned this year about using the newest generation of ICU ventilators include issues related to ventilator operation and ventilator monitoring. These are listed below.

1. Volume monitoring - The new generation of microprocessor ventilators uses a wide variety of flow/volume monitoring technologies. Perhaps more importantly, each uses signal conditioning prior to displaying volume. Practitioners should know if the value is compensated for tubing compliance or not, reported as BTPS, APTD or something else, and if the value is breath to breath or a rolling average.

2. Auto-PEEP - Automated measurement of auto-PEEP has been long awaited. How the ventilator calculates auto-PEEP, performs the expiratory hold, and the duration of expiratory hold are all important in the accurate determination of auto-PEEP.

3. Flow triggering- Flow triggering has been the range of work of breathing studies in the past several years. What are the real advantages of flow triggering, if there are any? Practitioners should know the principle of operation of the ventilators flow triggering system and the limitations of that system.

4. New Features - As long as there is competition, manufacturers will provide us with new modes and new names for old modes. The dual m odes of ventilation are the newest modes, including VAPS, Pressure augmentation, PRVC, autoflow, and volume support. Control, trigger, limit, cycle, and conditional variables for each of these modes should be known.

5. Breath shaping - Several new ventilators allow the clinician to adjust how quickly the initial flow or attack rate of the breath is provided. This is referred to as pressure slope, rise time, etc. What does this really do and how does the ventilator accomplish it. Could it be done automatically?

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