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Table 1 Definition of study objectives

From: Impact of oral melatonin on critically ill adult patients with ICU sleep deprivation: study protocol for a randomized controlled trial

Objective

Definition

Objective sleep quality

Total sleep time, the length of sleep at night (9:00 pm - 7:00 am) and during the day (7:00 am - 9:00 pm), sleep architecture (NREM stage 1 and 2, SWS, REM), and sleep disruption (the number of arousals and duration of sleep), which will be monitored for one 24-hour period using a portable PSG device.

Subjective sleep quality

The subjective feelings of nightly sleep status of the patient, including sleep depth, wake time after sleep onset, number of awakenings after sleep onset, latency to sleep onset, and sleep quality. It will be evaluated using the RCSQ[38, 39].

Anxiety level

ICU anxiety is defined as a state marked by apprehension, agitation, increased motor activity, number of arousals, and fearful withdrawal during the ICU stay[40]. It will be assessed using the VAS-A.

Delirium-free days in 8 and 28 days

Number of days that the patient is not delirious over 8 and 28 days starting from the day of inclusion. Patients are diagnosed as delirious when they have at least one positive CAM-ICU screening during their ICU stay. A delirium-free day is defined as a negative CAM-ICU screening during that day. In case a delirious patient is discharged from the ICU, a delirium-free day is defined as a delirium observation scale score of less than 3 during a complete day[41].

Ventilator-free days in 28 days

Time in days that the patient is not on a mechanical ventilator. If the patient is ventilated mechanically, including invasive and non-invasive ventilation several times during one ICU admission, then the non-ventilator times are added. Ventilator-free days (in 28 days) will be calculated.

Antibiotic-free days in 8 and 28 days

Number of days that the patient does not require any antibiotics at 8 and 28 days from randomization will be calculated.

ICU length of stay

Duration of admission to the ICU.

Overall ICU mortality at 28 days

Survival time will be assessed. Patients will be classified as either alive at study day 28 or dead at study day 28. Differences between the two strategies in mortality rates will be evaluated using the assumption of asymptotic normality. Estimates of relative risks and odds ratios and the corresponding 95% confidence intervals will be presented.

Side effects

Headache, dizziness, nausea, and drowsiness, determined daily by physical examination by the intensivist, and withdrawal symptoms upon discontinuation evaluated after the drugs are stopped.

  1. NREM, None rapid eye movement; SWS, Slow wave sleep; REM, Rapid eye movement; PSG, Polysomnography; RCSQ, Richards Campbell sleep questionnaire; VAS-A, Visual analogue scale-anxiety; CAM-ICU, The confusion assessment method for the intensive care unit.