The ARDSNet trial demonstrated the importance of low tidal volume ventilation in patients with ARDS, and we have learned to monitor parameters such as plateau pressure and driving pressure (DP) to ensure lung-protective ventilation. However, severe hypercapnia can occur with low tidal volume ventilation and respiratory rate would often need to be increased. What role does the higher respiratory rate play? There is growing evidence that respiratory rate may play an important part in the pathogenesis of ventilator-induced lung injury (VILI) and the dynamic effect of both rate and static pressures needs to be evaluated.

The concept of mechanical power (MP) was formalized in 2016 by Gattinoni, et al and defined as the product of respiratory rate and total inflation energy gained per breath.¹ Calculations have been developed for both volume-controlled and pressure-controlled ventilation, including elements such as respiratory rate and PEEP. Studies have shown that increased MP is associated with ICU and hospital mortality, even at low tidal volumes.² The use of MP remains limited in clinical practice due to its dynamic nature and difficulty of calculating in routine clinical practice but may be a feasible addition to the continuous monitoring outputs on a ventilator. Additional prospective studies are also needed to define the optimal threshold of MP and to compare monitoring strategies using MP vs DP.

References

1. Gattinoni L, Tonetti T, Cressoni M, et al. Ventilator-related causes of lung injury: the mechanical power. Intensive Care Med. 2016;42(10):1567-1575.

2. Serpa Neto A, Deliberato RO, Johnson AEW, et al. Mechanical power of ventilation is associated with mortality in critically ill patients: an analysis of patients in two observational cohorts. Intensive Care Med. 2018;44(11):1914-1922.