Comparison of patients with normal sleep versus atypical sleep on polysomnography (PSG)
| Normal sleep | Atypical sleep | p-value | |
| Subjects | 25 | 20 | |
| Patient characteristics | |||
| Age years | 62 (52–68) | 66 (55–75) | 0.58 |
| Male | 16 (64) | 16 (80) | 0.33 |
| BMI kg·m−2 | 30 (26–35) | 27 (24–38) | 0.66 |
| SAPS II at admission | 44 (38–54) | 49 (37–64) | 0.44 |
| Underlying cardiac disease | 9 (36) | 6 (30) | 0.76 |
| Underlying chronic lung disease | 11 (44) | 7 (35) | 0.76 |
| SBT failure prior to PSG | 1 (1–2) | 1 (1–1) | 0.22 |
| Duration of mechanical ventilation prior to PSG days | 5 (4–13) | 13 (7–19) | 0.02# |
| Length of ICU stay prior to PSG days | 6 (4–14) | 13 (10–20) | 0.02# |
| Days with sedation n | 3 (2–9) | 10 (6–14) | 0.02# |
| Cumulative dose of midazolam mg | 360 (144–1200) | 1308 (534–2670) | 0.02# |
| Sedation-free days at time of PSG n | 2 (1–3) | 3 (1–5) | 0.14 |
| Respiratory parameters at time of PSG | |||
| MIP cmH2O | 39 (34–54) | 42 (34–61) | 0.85 |
| P0.1 cmH2O | 3.6 (3.4–3.7) | 3.6 (3.5–3.8) | 0.59 |
| pH | 7.43 (7.40–7.46) | 7.43 (7.41–7.48) | 0.64 |
| PCO2 mmHg | 46 (39–54) | 42 (40–47) | 0.20 |
| PaO2/FIO2 mmHg | 235 (190–270) | 233 (184–255) | 0.79 |
| Clinical parameters at time of PSG | |||
| SOFA score | 3 (2–4) | 3 (3–4) | 0.26 |
| RASS score | 0 (0–0) | 0 (−0.3–0) | 0.82 |
| ICDSC score | 1 (0–4) | 3 (2–4) | 0.18 |
| Delirium | 8 (32) | 8 (40) | 0.76 |
| MRC score | 55 (36–60) | 36 (26–57) | 0.06 |
| ICU-acquired weakness (MRC score <48) | 9 (36) | 12/19 (63) | 0.13 |
| Severe weakness (MRC score <30) | 3 (12) | 8/19 (42) | 0.03# |
| Sleep duration | |||
| Duration of PSG recording h | 17 (16–19) | 17 (16–19) | 0.93 |
| Sleep duration h | 5 (2–7) | 3 (2–8) | 0.62 |
| Sleep efficiency % | 30 (13–39) | 19 (11–47) | 0.54 |
| Duration of sleep stage 1 min | 31 (11–50) | 0 (0–0) | <0.001# |
| Duration of sleep stage 2 min | 150 (69–206) | 0 (0–0) | <0.001# |
| Duration of deep sleep stage 3 min | 57 (30–120) | 0 (0–0) | <0.001# |
| Duration of REM sleep stage min | 31 (0–53) | 0 (0–4) | 0.001# |
| Sleep quality | |||
| Absence of deep sleep stage 3 | 2 (8) | 20 (100) | <0.001# |
| Absence of REM stage | 7 (28) | 13 (65) | 0.02# |
| Absence of EEG reactivity at eyes opening | 0 (0) | 12 (60) | <0.001# |
| Altered EEG reactivity at eyes opening | 4/23 (17) | 18 (90) | <0.001# |
| Outcomes | |||
| Duration of mechanical ventilation after PSG days | 2 (1–2) | 5 (2–8) | <0.001# |
| Prolonged weaning (>48 h) | 4 (16) | 14 (70) | <0.001# |
| Total duration of mechanical ventilation days | 10 (6–15) | 21 (15–29) | <0.01# |
| Length of ICU stay days | 13 (9–22) | 24 (21–36) | <0.01# |
| Mortality in ICU | 1 (4) | 4 (20) | 0.15 |
Data are presented as n, median (interquartile range), n (%) or n/N (%), unless otherwise stated. BMI: body mass index; SAPS: Simplified Acute Physiological Score; SBT: spontaneous breathing trial; ICU: intensive care unit; MIP: maximal inspiratory pressure; P0.1: negative airway pressure generated against occlusion during the first 0.1 s of spontaneous inspiration; PCO2: carbon dioxide tension; PaO2: arterial oxygen tension; FIO2: inspiratory oxygen fraction; SOFA: Sequential Organ Failure Assessment; RASS: Richmond Agitation–Sedation Scale; ICDSC: Intensive Care Delirium Screening Checklist; MRC: Medical Research Council; REM: rapid eye movement; EEG: electroencephalogram. #: p<0.05.