Using Pressure Support in a Rational Way

Abstract

The main thrust of my article was not intended to be a comparison of high level pressure support ventilation and SIMV. Rather, the major goal of the article was to describe respiratory drive and the patient’s work as a function of pressure support levels ranging from very high (ie, PSVmax) to very low (ie, approaching unsupported breathing). The results clearly showed that, as pressure support is lowered toward 0, respiratory rate increases, tidal volume decreases, the patient’s work increases, and the pressure/volume change (P/AV) characteristics of this work increase. These observations provide a rational basis for a weaning protocol that uses decreasing levels of pressure support ventilation alone. This approach allows considerable patient control over the ventilatory pattern (ie, the rate and the inspiratory flow) during the weaning process. Moreover, this approach would appear to offer the potential benefit of supplying a more regular (ie, with every breath) workload with P/AV characteristics resembling normal breathing. Improved patient comfort would not be surprising under these circumstances and it can be speculated that a more appropriate muscle-conditioning workload might also result.