This chapter addresses the role of assessing patient-ventilator synchrony at the bedside and optimizing ventilatory settings during assisted ventilation. The hypothesis is that it is better for the patient to have a ventilator working in synchrony with the patients own inspiratory and expiratory rhythm. Although this is likely to be true in general, in some circumstances it probably does not matter so much. To what extent the clinician has to repeatedly make optimal adjustments ofventilatory settings is sometimes difficult to determine. It is important, however, to realize that improper adjustments can generate major dysynchrony, make the patient uncomfortable, and/or unnecessarily increase the work of breathing. This is also probably a major reason for administration or increase in sedation. Whether automated systems making these adjustments based on reasonable physiological grounds will benefit both the patient and the clinician is also an interesting and important question for the future of intensive care medicine [1, 2].
Mechanisms explaining patient-ventilator dysynchrony are explored with greater details in another chapter. Whereas the interaction between the patient and the ventilator has often been described as a fight, this chapter will also suggest that a similar fight may exist between the clinician and the ventilator.
Because mechanical ventilation is delivered on a 24-hour basis, inadequate adjustment leading to excessive work of breathing may potentially have important consequences on global metabolism, regional blood flow redistribution and respiratory muscle performance. However, at the opposite end, excessive unloading of the respiratory muscles inducing disuse atrophy may rapidly change muscle fiber components and profoundly reduce respiratory muscle force and endurance.
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