The challenge of patient-ventilator interaction
“We have recognized that keeping patients deeply sedated is bad and that having them walk, sit, and interact while intubated is good. Moreover, we have to deal with patient-ventilator synchrony issues while trying to limit the pressures and tidal volumes – often conflicting goals. These principles have made the recognition and optimization of the patient ventilator interaction more relevant than ever.”
Eduardo Mireles-Cabodevia, MD and our friend Robert L. Chatburn, MHHS, RRT-NPS, FAARC were featured in an June 2017 AARC Times article, discussing the challenges we are faced with when managing a patient on a ventilator. The problem, they explain, is the lack of consistency amongst ventilator manufacturers and educators. There is no standard vocabulary, no standard ventilator mode functionality, and no clear understanding of what each interaction means in terms of clinical implications.
“Abnormal patient-ventilator interactions are common, frequently overlooked, not part of regular charting, often treated with sedatives, and in general there is no systematic approach to dealing with it.” When we use the term “synchrony” we are talking about time – timing of the trigger and cycling- but we see patient-ventilator interaction in terms of flow delivery. With this, we see that “flow asynchrony” refers to a mismatch of inspiratory work supply and demand.
There are several basic technological features that improve this mismatch between patient and ventilator. The chart below outlines common types of patient-ventilator interactions as well as their solutions.
The clinician should take into account that for most mechanical breaths, there will be some degree of dyssynchrony. You could spend hours trying to fine-tune the ventilator to match every breath , but it may turn out to be irrelevant. “Two words of caution. First, consider the clinical scenario and the severity/consequences of the a/dyssynchrony. Second, we have a lot of technology, but very little patient-level evidence. Learn what your ventilator really does and use the best available evidence and physiology understanding.”