THE EFFECT OF PHYSICAL REHABILITATION ON REPEATED SUSTAINED ATTENTION TESTS IN CRITICALLY ILL PATIENTS

Abstract

Introduction Delirium, a clinical syndrome defined as an acute and fluctuating disturbance of consciousness and impaired attention (American Psychiatry Association, 2013), affects up to 90% of mechanically ventilated patients in the intensive care unit (ICU) and is associated with long-term cognitive impairment (Pandharipande, et al., 2013). While evidence for pharmacological therapy for delirium is limited, several non-pharmacological interventions, including physical rehabilitation, reduce delirium incidence and duration (Alvarez et al., 2009; Schweickert et al., 2009). This study evaluates the effects of physical rehabilitation on attention - a fundamental cognitive domain disrupted in delirium. Methods Adult medical ICU patients without neurological pathology, dementia, or coma, receiving physical rehabilitation as part of routine care were included in this study. All patients were assessed for delirium at approximately 8 am, and then completed two standardized tests of attention, separated by about 3 hours, using the Edinburgh Delirium Test Box for the ICU (EDTB-ICU) (Green et al., 2017). The EDTB-ICU is a non-invasive, computerized neuropsychological testing device that quantitatively measures attention via a method that is suitable for non-verbal ICU patients, including those who are mechanically ventilated. The EDTC-ICU includes 3 levels of increasing difficulty, consisting of 3 trials each, with a total score range of 0-9. Patients were randomized in a 1:1 ratio to complete the second attention test either before vs. after the routine care physical therapy session (referred to as the control vs. study group, respectively) using computer-generated permuted block randomization created using STATA 14. The allocation sequence was concealed from the researcher, but assessors were not blinded to treatment condition. Baseline data regarding patients’ cognitive and functional status were collected from direct testing and informant interview. Delirium was assessed via the Confusion Assessment Method (CAM) (Inouye et al., 1990) and Delirium Rating Scale-Revised-98 (DRS-R98) (Trzepacz et al., 2001). Each instrument was rated after direct standardized cognitive function testing and patient examination, medical record review, and collateral informant interview by trained personnel. Patient performance on the EDTB-ICU did not contribute to these ratings and was evaluated separately. Group differences in baseline data were compared using Mann-Whitney U tests for continuous variables and Fisher's exact tests for dichotomous variables. Within-subject change in sustained attention performance was calculated using the Wilcoxon signed-rank test. To compare the effect of intervening physical rehabilitation (study group) vs. no physical rehabilitation (control group) on change in attention, a mixed effects model with a random intercept was fitted. Significance was defined as p Results Of 1,711 patients screened, 31 were eligible, consented and completed the study protocol (Fig. 1). Table 1 reports baseline characteristics of the cohort (n=31), study group (n=15), and control group (n=16). The two groups were similar at baseline. Table 2 reports median initial and repeat EDTB-ICU scores. The control group declined by an average of 1.0 point (95% CI: -1.9, -0.1; p=0.02) while the study group declined by an average of 0.3 points (95% CI: -2.4, 1.9; p=0.2). This difference in change over time between the study vs. control group was not significantly different (p=0.25). Conclusions This pilot study did not demonstrate a significant difference in sustained attention for critically ill patients who were randomized to receive repeated attention testing with vs. without intervening physical rehabilitation. Given prior randomized controlled trials demonstrating reductions in delirium in ICU patients receiving vs. not receiving physical rehabilitation, larger-sized studies evaluating the impact of physical rehabilitation on attention, a critical domain in assessing delirium, are needed to further investigate these findings. This research was funded by Research Funding Source: Hitachi Ltd.