Pressure Support Ventilation Advisory System Provides Valid Recommendations for Setting Ventilator

Abstract

BACKGROUND: Pressure support ventilation (PSV) should be applied so that the inspiratory muscles are unloaded appropriately. We developed a computerized advisory system that assesses the load on the inspiratory muscles to spontaneously inhale, reflected by the automatically and noninvasively measured work of breathing per minute, and tolerance for that load, reflected by spontaneous breathing frequency and tidal volume, in a fuzzy-logic algorithm that provides recommendations for setting PSV. We call this a load and tolerance strategy for determining PSV. METHODS: In a clinical validation study, we compared the recommendations from our PSV advisory system to the recommendations of experienced critical-care Registered Respiratory Therapists (RRTs) for setting PSV in patients with respiratory failure. With 76 adult patients in a university medical center surgical intensive care unit receiving PSV, a combined pressure/flow sensor, positioned between the endotracheal tube and patient Y-piece, sent measurements to the PSV advisory system. We compared the advisory system's recommendations (increase, maintain, or decrease the pressure support) to the RRTs' recommendations at the bedside. RESULTS: There were no significant differences between the RRTs' and the advisory system's recommendations (n ‫؍‬ 109) to increase, maintain, or decrease PSV. The RRTs agreed with 91% of the advisory system's recommendations (kappa statistic 0.85, P < .001). The advisory system was very good at predicting the RRTs' pressure support recommendations (r 2 ‫؍‬ 0.87, P < .02). CONCLUSIONS: A load and tolerance strategy with a computerized PSV advisory system provided valid recommendations for setting PSV to unload the inspiratory muscles, and the recommendations were essentially the same as the recommendations from experienced critical-care RRTs. The PSV advisory system operates continuously and automatically and may be useful in clinical environments where experts are not always available.

Respiratory Mechanics in Mechanically Ventilated Patients

“…WOB is calculated from the measured V I and the P calculated from the equation of motion: WOB ϭ ͐P ϫ V. Power of breathing (WOB/min) is the rate at which work is done as a measure over time, not for an individual breath. [42][43][44][45][46] This may be a better assessment of respiratory muscle load than WOB/breath. Normal power of breathing is 4 -8 J/min.…”

Clinical characteristics and outcomes of mechanically ventilated patients in respiratory intensive care unit according to weaning classification

“…Hepatic vascular resistance is also elevated in mechanically ventilated patients. (23) As regard serum urea level, Patients with elevated urea level were significantly experienced difficult and prolonged weaning in comparison to patients with simple weaning (P= 0.005& 0.004 respectively),these results was in agreement with the result of the study of Yao-Kuang, et al (24) who reported that high blood urea nitrogen (BUN) levels were associated with weaning failure, this can be explained as elevated BUN levels may be indicative of impaired renal function, reduced kidney blood flow and/or excessive protein catabolism resulting in muscle wasting and a negative nitrogen balance.…”

Man Versus Machine: What's the Standard?

“…In this issue of RESPIRATORY CARE, Bonnett and colleagues 4 "reintroduce" readers to a computerized system meant to aid in the provision of care to patients requiring mechanical ventilation. They described an open-loop advisory system that continuously provides caregivers recommendations relevant to the titration of pressure support ventilation (PSV).…”