Ventilation management in Victorian intensive care unit patients without acute respiratory distress syndrome

The setting of tidal volume (V_T) during controlled mechanical ventilation (CMV) in critically ill patients without acute respiratory distress syndrome (ARDS) is likely important but currently unknown. We aimed to describe current CMV settings in intensive care units (ICUs) across Victoria.

We performed a multicentre, prospective, observational study. We collected clinical, ventilatory and arterial blood gas data twice daily for 7 days. We performed subgroup analysis by sex and assessment of arterial partial pressure of carbon dioxide (PaCO₂) management where hypercapnia was potentially physiologically contraindicated.

We recorded 453 observational sets in 123 patients across seven ICUs. The most commonly selected initial V_T was 500 mL (33%), and this proportion did not differ according to sex (32% male, 34% female). Moreover, 38% of patients were exposed to initial V_T per predicted body weight (V_T-PBW) > 8.0 mL/kg. V_T-PBW in this range were more likely to occur in females, those with a lower height, lower ideal body weight or in those for whom hypercapnia was potentially physiologically contraindicated. As a consequence, females were more frequently exposed to a lower PaCO₂ and higher pH.

In adults without ARDS undergoing CMV in Australian ICUs, the initial V_T was a stereotypical 500 mL in one-third of participants, irrespective of sex. Moreover, around 40% of patients were exposed to an initial V_T-PBW > 8.0 mL/kg. Finally, women were more likely to be exposed to a high V_T and hyperventilation.