The Injurious Effects of Elevated or Nonelevated Respiratory Rate during Mechanical Ventilation

Abstract

Respiratory rate is one of the key variables we set and monitor during mechanical ventilation. As part of our increasing efforts to optimise mechanical ventilation, it is prudent that we expand our understanding of the potential harmful effects not only of volume and pressures, but also of respiratory rate. The mechanisms by which respiratory rate may become injurious during mechanical ventilation can be distinguished in two broad categories. In the first well-recognised category, concerning both controlled and assisted ventilation, the respiratory rate per se may promote ventilator-induced lung injury, dynamic hyperinflation, ineffective efforts and respiratory alkalosis. It may also be misinterpreted as distress delaying the weaning process. In the second category, which concerns only assisted ventilation, the respiratory rate may induce injury in a less apparent way, by remaining relatively quiescent while being challenged by chemical feedback. By responding minimally to chemical feedback, respiratory rate leaves the control of minute ventilation almost exclusively to inspiratory effort. In such cases, when assist is high, weak inspiratory efforts promote ineffective triggering, periodic breathing and diaphragmatic atrophy. Conversely, when assist is low, diaphragmatic efforts are intense and increase the risk for respiratory distress, asynchronies, ventilator-induced lung injury, diaphragmatic injury, and cardiovascular complications. This review thoroughly presents the multiple mechanisms by which respiratory rate may induce injury during mechanical ventilation, drawing the attention of critical care physicians to the potential injurious effects of respiratory rate insensitivity to chemical feedback during assisted ventilation.

Inspiratory effort and breathing pattern change in response to varying the assist level: A physiological study

“…Therefore, at the presence of neuromuscular weakness, respiratory center activity during inspiration may be high causing an increase in respiratory rate despite normal inspiratory pressure during inspiration. This observation is in line with several studies showing a higher than normal respiratory rate in critically ill patients (Akoumianaki et al, 2019;Giannouli et al, 1999;Marantz et al, 1996). Moreover, a low respiratory rate was not uncommon, despite a high respiratory drive and effort, highlighting the inadequacy Fig.…”

Non-invasive ventilatory support and high-flow nasal oxygen as first-line treatment of acute hypoxemic respiratory failure and ARDS

“…Inspiratory effort may be a specific predictor of the need for intubation, as it reflects the underlying severity, and it is the main determinant of P-SILI. Despite not being a reliable index of effort [ 116 ], respiratory rate remains the most used surrogate of respiratory drive because of its simplicity to use. Low or decreasing respiratory rate is associated with success of noninvasive support [ 117 , 118 ].…”

Network Data Acquisition and Monitoring System for Intensive Care Mechanical Ventilation Treatment

“…is the number of breaths per minute. High respiratory rate can provide adequate minute ventilation with lower peak inspiration pressure but may cause insufficient inspiratory or expiratory time, and ventilatorinduced lung injury [61]. The RR is approximated by dividing average breath time in seconds by a total of 60 seconds, as defined:…”