Twenty-Four Years Later: Are We Still Selecting the Right Tidal Volume?

Abstract

Background: Twenty-four years ago, the ARDSNet trial promoted setting initial tidal volumes (V_T) of 6-8 mL/kg of ideal body weight (IBW) to reduce the risk of ventilator-induced lung injury (VILI) and decrease mortality. Despite the evidence, this lung protective approach continues to be inconsistently implemented. This study was designed to evaluate adherence to this low-V_T (LTV) strategy in a group of patients receiving mechanical ventilation (MV) at large university-affiliated institution in Texas.

Methods: This retrospective descriptive non-experimental study was conducted in the ICU at University Hospital in San Antonio, Texas, between March 2022 and April 2022. Patients admitted to the ICU aged 18 to 80 years old who received mechanical ventilation more than 24 h were included in this study. Selected V_T was recorded for every subject and compared to recommended LTV strategy. General information and ventilator parameters collected included IBW, V_T, PEEP, PIP, IBW, MAP and FIO₂. Descriptive statistical analyses were conducted on the collected data. The Institutional Review Board approved this study.

Results: Of the 61 subjects included in the study the median age was 53 y old (± 17.6). Most were male (65.6%) and Hispanic (45.9%). Mean V_T was 436 mL (± 57.1; range: 270-450 mL). Based on IBW, the V_T selected was 6.68 mL/kg/PBW (SD 1.03; range: IQR 25-75 5.94-8.36). The most selected V_T was 420 mL (n = 11, 18%), followed by 420 mL (n = 10, 16%). Almost 1 out of 4 subjects (24.6%) were placed on a V_T ≤ 6 mL/kg PBW, and 14% received a set V_T of > 8 mL/kg PBW. While most subjects (98.3%) were on volume-limited ventilation, Pplat was measured and documented in only 64% of the subjects.

Conclusions: Most patients ventilated in this medical ICU were placed on V_Ts appropriate for the IBW. However, selection of a tidal volume below and above the published guidelines on almost 50% of the subjects in this study indicates a need for better adherence to recommendations to reduce the risk of atelectrauma or overdistension.