Intraoperative low tidal volume ventilation and the risk of ICD-10 coded delirium and the use for antipsychotic medications.

Background: Low tidal volume (V) ventilation and its associated increase in arterial carbon dioxide (PaCO) may affect postoperative neurologic function. We aimed to test the hypothesis that intraoperative low V ventilation affect the incidence of postoperative ICD-10 coded delirium and/or the need for antipsychotic medications.

Methods: This is a post-hoc analysis of a large randomized controlled trial evaluating low vs. conventional V ventilation during major non-cardiothoracic, non-intracranial surgery. The primary outcome was the incidence of ICD-10 delirium and/or the use of antipsychotic medications during hospital stay, and the absolute difference with its 95% confidence interval (CI) was calculated.

Results: We studied 1206 patients (median age of 64 [55-72] years, 59.0% males, median ARISCAT of 26 [19-37], and 47.6% of ASA 3). ICD-10 coded delirium and /or antipsychotic medication use was diagnosed in 11.2% with similar incidence between low and conventional V ventilation (11.1% vs. 11.3%; absolute difference, -0.24 [95%CI, -3.82 to 3.32]; p = 0.894). There was no interaction between allocation group and type of surgery.

Conclusion: In adult patients undergoing major surgery, low V ventilation was not associated with increased risk of ICD-10 delirium and/or the use of antipsychotic medications during hospital stay.

Trial Registration: ANZCTR Identifier: ACTRN12614000790640 .