Special Article
Intraoperative adherence to a low tidal volume ventilation strategy in critically ill patients with preexisting acute lung injury,☆☆

https://doi.org/10.1016/j.jcrc.2010.08.002Get rights and content

Abstract

Purpose

Low tidal volume (LTV) ventilation reduces mortality in patients with acute lung injury (ALI) or acute respiratory distress syndrome (ARDS). This study investigates adherence of intraoperative LTV and whether patient outcomes were different with or without continued intraoperative LTV ventilation in patients with previously established ALI or ARDS.

Materials and Methods

A retrospective analysis was performed of adults with ALI/ARDS over a 2-year period who underwent surgery between 24 hours and 14 days after the diagnosis of ALI/ARDS. The main outcome was intraoperative LTV use. Secondary outcomes included perioperative respiratory and clinical outcomes.

Results

Of the 249 patients who underwent surgery between 24 hours and 14 days after ALI/ARDS diagnosis, 101 (41%) received preoperative LTV ventilation. Fifty-four (53%) received intraoperative LTV ventilation, whereas 47 (47%) did not. Use of preoperative LTV ventilation was associated with use of intraoperative LTV ventilation (P < .01). No differences in respiratory or clinical outcomes between patients with or without intraoperative LTV ventilation were observed.

Conclusions

Adherence to intraoperative LTV in surgical patients was low. Adherence of LTV intraoperatively was not associated with improved oxygenation, reductions in hospital length of stay, or in-hospital mortality. The importance of adhering to an intraoperative LTV strategy remains unclear.

Introduction

Experimentally, mechanical ventilation with large tidal volumes can result in lung injury (ventilator-induced lung injury [VILI]). Ventilator-induced lung injury manifests as ultrastructural injury and leads to both local and systemic inflammation [1], [2], [3]. Attempts to reduce VILI include lung protective ventilation (LPV) strategies such as use of low tidal volumes (LTVs) and the appropriate titration of positive end-expiratory pressure (PEEP) [1], [4], [5], [6], [7]. Tidal volume (VT) reduction has been shown to improve survival among patients with established acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) in a randomized controlled trial conducted within the Acute Respiratory Distress Syndrome Network (ARDSnet) [7].

Despite recognition that LPV is beneficial in ALI/ARDS patients, widespread implementation of the ARDSnet protective ventilation strategy has been slow. Many institutions still use larger than recommended VTs, which may place patients at increased risk of morbidity and mortality related to VILI [5], [8], [9], [10]. In addition, little information is available regarding the adherence and/or the efficacy of LPV during surgery and general anesthesia in patients with previously established ALI/ARDS. This is an important gap in knowledge because surgical patients already suffering from lung injury may be at risk of worsened outcomes due to the additional “hit” of general anesthesia and surgery.

Therefore, we performed a study to investigate the adherence to intraoperative LPV strategies during anesthesia and surgery, and whether outcomes were any different between patients who did and did not receive continued intraoperative LPV. We used LTV as a surrogate for LPV because airway plateau pressures (PPLs) are not routinely recorded in the operating room. We hypothesized that intraoperative LTV use is infrequent and that adherence to an intraoperative LTV strategy might be associated with improved respiratory and patient outcomes.

Section snippets

Methods

This study was approved by the University of Washington Institutional Review Board, which waived the requirement for informed consent.

Demographics and clinical data

Among the 249 patients with ALI/ARDS, 101 (41%) patients received preoperative LTV. Of the 249 (age, 49.3 ± 17.3 years; range, 18-90 years) critically ill patients who had surgery and general anesthesia 24 hours to 14 days after ALI/ARDS diagnosis and eligible to receive preoperative LTV, most were male (65.5%), were white (75.5%), and suffered from trauma (70%). The mean APACHE II score was 17 ± 6 (range, 4-44), and mean ISS was 40 ± 15 (5-75). In addition to trauma, risk factors for ALI/ARDS

Discussion

A large, multicenter, randomized, controlled trial demonstrated that ventilation using a lung protective strategy including VTs of 6 mL/kg PBW in the ICU results in a lower mortality rate than traditional ventilation using VTs of 12 mL/kg in patients with ALI/ARDS [1], [4], [12], [13], [14]. However, subsequent reports have documented either no change or a modest alteration in practice in terms of application of LPV to patients with ALI and ARDS [5], [8], [9], [15]. In addition, there is

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    Funded by Harborview Anesthesiology Research Center and National Institutes of Health HL067982.

    ☆☆

    This work will be attributed to the Department of Anesthesiology and the Department of Medicine, University of Washington School of Medicine, VA Puget Sound Health Care System, Seattle, WA.

    Deceased.

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