Neuropsychological follow-up of isoflurane sedated intensive care patients: a substudy of a randomized trial.

Background: Inhaled sedation of intensive care unit (ICU) patients ventilated >24 hours may have long term effects. We hypothesized that isoflurane has a better neuropsychological outcome in a one-year follow-up compared to propofol sedation.

Methods: All 66 patients included by the coordinating center of the ISOCONDA study (EudraCT#: 2016-004551-67) took part in this substudy (DRKS00020240). A delirium test (CAM-ICU) was performed 24 hours after end of sedation. Sedation-, ventilator-, ICU- and delirium-free days within 30 days were calculated. Patients were sent five questionnaires one, three and twelve months after ICU discharge: ICU-Memory-tool (ICU-MT), Short-Form-36-Health-survey (SF-36), Posttraumatic-Stress-Scale-14 (PTSS-14), WHO-Five-Well-Being-Index (WHO-5) and Hospital-Anxiety-Depression-Scale (HADS).

Results: CAM-ICU was positive in 17% of patients, however 68% showed signs of delirium during the ICU stay (no group differences). Mortality was lower after isoflurane (30-days: 1/33 versus 7/33, P=0.024; One-year: 9/33 versus 14/33, P=0.156). Isoflurane led to significantly more sedation- (median [IQR]: 28[25-29] versus 24[21-29], P=0.016), ventilator- (28[24-29] versus 22[4-28], P=0.011), ICU- (23[13-26] versus 11[0-25], P=0.044) and delirium-free days (25[21-29] versus 20[12-28], P=0.031). Return rate of questionnaires was high (87/128). In the ICU-MT, isoflurane patients recalled significantly more factual memories after one year. Generally, the psychological tests suggested a poor quality of life (SF-36), high rates of post-traumatic-stress-disorder (PTSS-14: 38%) and depression (WHO-5: 54%, HADS: 43%), without significant group differences.

Conclusions: Isoflurane sedation leads to more delirium free days during the ICU treatment and more factual memories of the ICU stay one year after the ICU stay. However long-term outcome of ventilated ICU patients is poor, and there were no differences between isoflurane and propofol sedation.