PURPOSE: Mechanical ventilation is frequently utilized to support patients in intensive care units (ICU). Even though a majority of these patients require mechanical ventilation for respiratory failure, a significant proportion do not have any acute respiratory compromise. Despite substantial advances in various modes of ventilation, there is considerable morbidity and mortality in patients receiving mechanical ventilation. Various studies have shown mechanical ventilation can induce lung injury. A landmark multicenter randomized trial has proven benefit of low tidal volume in patients with acute lung injury (ALI) or acute respiratory distress syndrome (ARDS). Furthermore, in patients without underlying ALI or ARDS, there is evidence of sustained increase in plasma cytokine levels in patients receiving mechanical ventilation with conventional tidal volumes compared to those with lower tidal volumes. Higher tidal volume has also been linked to development of ARDS in animal studies and retrospective analysis. The objective of our study was to determine correlation between high tidal volume and various outcome measures in ICU patients.
METHODS: Retrospective review of tidal volumes and APACHE IV data was performed on charts of 677 patients.
RESULTS: Tidal Volume (TV) of 8mL/kg predicted body weight (PBW) was used to divide the patients in two groups. Of 677 patients, 572 received TV of more than 8mL/kg at some point during their ICU stay as opposed to 105 patients whose TV remained less than 8 mL/kg PBW. Patients who received TV of more than 8mL/kg had significantly higher ICU mortality compared to those with lower tidal volumes (26.8% versus 17.6%; p-value = 0.05). Patients in higher TV group also had significantly longer ICU stay. There was a trend towards poor functional status at the time of discharge in higher tidal volume group, but this did not reach statistical significance. Hospital length of stay did not show a correlation with the amount of tidal volume.
CONCLUSIONS: Our study shows higher tidal volume can be related to significant morbidity and mortality
CLINICAL IMPLICATIONS: We recommend careful monitoring to maintain low tidal volumes in mechanically ventilated patients including those with non-respiratory critical illness.
DISCLOSURE: The following authors have nothing to disclose: Numaan Malik, Meng Xu, Lori Griffiths, Madhu Sasidhar
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