Intraoperative Infusion of Dexmedetomidine for Prevention of Postoperative Delirium in Elderly Patients

Postoperative delirium is assessed by the combination of the Richmond Anxiety Scale (RASS) and the Confusion assessment method for intensive care unit (CAM-ICU) or the 3-minute diagnostic interview for CAM (3D-CAM) as applicable.

Delirium consists of four main characteristics: acute onset of a change in mental status or a fluctuating level of consciousness, inattention, disorganized thinking and an altered level of consciousness. The patient was diagnosed as delirious if both the first and second features were present, and either the third or fourth was present.

In the ICU, the delirium assessment was performed in two steps. The arousal level was first assessed by RASS. If the patient was not responsive to verbal stimuli (i.e. RASS score ≤-4), the remaining delirium assessment was aborted, and the patient was recorded as comatose. When the RASS score was greater than or equal to 3, delirium was evaluated using the CAM-ICU. Patients in general ward were evaluated by 3D-CAM.

The degree of surgical incision pain will be assessed at rest and on movement by Numerical Rating Scale (NRS). NRS ranges from 0 to 10, with the highest score indicating the worst pain.

The quality of recovery will be assessed with 15-item quality of recovery questionnaire (QoR-15). The QoR-15 measures cognitive function, physical activity, language and mood on a 150-point scale, with higher scores indicating better quality of recovery.

The quality of sleep will be assessed by the Richards Campbell sleep questionnaire (RCSQ).RCSQ is mainly used to evaluate the sleep quality of the previous night. The scale comprises five items: sleep depth, sleep latency, wake up times, relapse to sleep and overall sleep quality.The total score of the scale is the average of 5 items, and the lower the score, the better the sleep quality.

Cognitive function will be assessed 1 day before surgery and 5 days after surgery using MMSE scale and Montreal Cognitive Assessment (MoCA) scale. MMSE includes seven items: time orientation, place orientation, immediate memory, attention and calculation, delayed memory, language and visual space.A total of 30 questions will be asked, 1 point for each correct answer, 0 point for a wrong answer or unknown answer and the total score range from 0 to 30. MoCA scale was widely identified that MoCA was superior to MMSE in the detection of mild cognitive impairment. Furthermore, the MoCA showed differences in cognitive profile even in those performing in the normal range on the MMSE and would appear to be a useful brief tool to assess cognition in those with mild cognitive impairment.

Psychological health state will be assessed by Generalized Anxiety Disorder-7 (GAD-7) and Patient Health Questionnaire-9 (PHQ-9).There are 7 and 9 items to screen anxiety and depression, respectively. The point of each item is 3. The total points >4 will be regarded as anxiety and depression.

Intraoperative data include total dose of anesthetics, bispectral index scale value, and cardiovascular adverse events will be recorded and classified as hypotension (systolic blood pressure<95mmHg, or lower than 30% baseline), hypertension (systolic blood pressure ≥180 mmHg, or higher than 30% baseline), bradycardia (heart rate <40 beats /min), tachycardia (heart rate ≥ 100 beats /min) or hypoxemia (pulse oxygen saturation<90%).

Non-delirium complications include cardiac arrest, infection of the incision, sepsis, intracranial hematoma, severe intracranial edema (base on brain images), stroke, myocardial infarction, pulmonary infection and embolism.

Postoperative 30-day all-cause mortality.

The physiological status of the patients will be assessed by Short-Form Mini-nutrition assessment (MNA-SF) and FRAIL scale.

Electroencephalogram will be used to record the brain activity.

Regional cerebral oxygen saturation will be monitored with near-infrared spectroscopy.