Do we practise low tidal-volume ventilation in the intensive care unit? a 14-year audit

Low tidal volume ventilation (LTVV) has been shown to reduce mortality of patients with acute lung injury (ALI) but uptake by clinicians has been low. Recent studies have shown that LTVV results in survival benefit at 24 months after discharge and, importantly, benefits patients without ALI.

To determine adherence to LTVV in patients on mechanical ventilation (MV).

Retrospective analysis of ventilator settings recorded within the clinical information system of a 15-bed general ICU in a tertiary referral hospital, between 1 January 2000 and 31 May 2013.

Analysis of mandatory MV with volume or pressure control.

Adherence to LTVV (_6.5 mL/ kg predicted body weight [PBW]).

We studied 4923 patients with a median age of 66 years (interquartile range [IQR], 57-74 years), and a median Acute Physiology and Chronic Health Evaluation II score of 16 (IQR, 13-19). Included were 3486 men (70.8%), and 3386 (66.8%) had undergone cardiac surgery. There were 249 450 ventilator measurements, with a median per patient of 75 measurements (IQR, 17-255 measurements). The median tidal volume was 8.15 mL/kg PBW (IQR, 7.15- 9.34 mL/kg PBW) for an adherence of 13.4%. Independent factors associated with adherence were sex, high inspiratory pressures, high positive end expiratory pressure and low PaO2/FiO2 ratio.

Adherence to LTVV in a general cohort of ICU patients was low, but it was better in patients with more severe lung disease. Overestimation of PBW may have contributed to our findings. Regular auditing of LTVV adherence might be considered a clinical indicator of good MV practice.