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©The Author(s) 2023.
World J Crit Care Med. Jun 9, 2023; 12(3): 92-115
Published online Jun 9, 2023. doi: 10.5492/wjccm.v12.i3.92
Published online Jun 9, 2023. doi: 10.5492/wjccm.v12.i3.92
Table 1 Simplified polysomnographic features of the American Academy of Sleep Medicine’s phases of sleep
Sleep stage | Electroencephalogram | Electrooculogram | Chin electromyogram |
Wake | Alpha activity (sinusoidal 8-13 Hz) | Rapid eye movements; Reading eye movements; Slow eye movements; Blinks | Normal or high tone |
N1 | < 50% alpha activity; > 50% low amplitude mixed frequency activity (4-7 Hz) | Slow eye movements | Variable, usually lower than wake |
N2 | Sleep spindles; K-complexes | None | Variable tone |
N3 | Slow (delta) wave (0.5-2 Hz) ≥ 20%; Sleep spindles may occur | None | Variable tone |
REM | Low amplitude mixed frequency activity; No sleep spindles or K-complexes | Rapid eye movements | Low tone |
Table 2 Comparison of studies assessing the effects of ventilator mode on sleep quantity and quality
Ref. | Study Design | n | Treatment arms | Sedation | Outcomes | ||
Studies comparing pressure support ventilation against assist control ventilation | |||||||
Parthasarathy et al[79], 2002 | Single centre, randomised, cross over study | 11 | 2 h each of: | ACV; Vt: 8 mL/kg; f: Set as patient RR minus 4/min | Yes | Sleep efficiency: Arousal index, mean (SD) | Not reported; ACV 39 (6); PSV 35 (7); No statistically significant difference between ventilation modes |
Toublanc et al[81], 2007 | Single centre, randomised, cross over study | 20 | 4 h each of: | ACV; Vt: 10 ml/kg; f: 12/min; Increased until no spontaneous inspiratory effort | Free from sedation for 48 h | Sleep efficiency: Arousal index, mean (SD) | No difference, values not reported; ACV 7 (SD 5); PSV 7 (SD 5); No statistically significant difference between ventilation modes |
Cabello et al[82], 2008 | Single centre, randomised, cross over study | 15 | 6 h each of: cPSV; PS to achieve Vt 6-8 ml/kg (PBW); RR < 35/min; aPSV | ACV; Vt: 8 mL/kg; f: 10/min (back up) | Free from sedation for 24 h | Sleep efficiency, median [IQR]: Arousal index, median [IQR] | ACV 58 [48-82], cPSV 44 [29-30], aPSV 63 [29-80]; ACV 30 [17-41], PSV 28 [17-53], aPSV 23 [21-45]; No statistically significant difference between ventilation modes |
Studies comparing pressure support ventilation against pressure control ventilation | |||||||
Andréjak et al[83], 2013 | Single centre, randomised,cross over study | 26 | 4 h each of: | PCV; PS = 20 cmH2O; f: Greater than patient RR I/E ratio: 1/1.2 to 1/1.5 | Not reported | Sleep efficiency, median [IQR]: Arousal index | PCV 63 [9-100]; PSV 37 [0-96] Not reported; Significantly improved sleep efficiency with PCV |
Studies comparing pressure support ventilation against proportional assist ventilation | |||||||
Bosma et al[84], 2007 | Single centre, randomised, cross over study | 13 | 1 night each of: PSV | PAV | Propofol, midazolam or lorazepam | Sleep efficiency, mean (SD): Arousal index, median [IQR]: Patient-ventilator asynchrony per hour, mean (SD) | PSV 58% (25); PAV 60 (23); PSV 16 (2-74); PAV 9 (1-41); PSV 53 (59); PAV 24 (15); PAV associated with statistically significantly fewer arousals and episodes of asynchrony |
Alexopoulou et al[85], 2007 | Single centre, randomised, cross over study | 17 | 1 night each of: | PAV+base; Set to achieve mean inspiratory pressure similar to PSVbase; PAV+high; Percentage of unloading increased by 40%-50% from PSVbase or until it reached 85% | Group A; n = 11; Propofol; Group B; n = 9; Non-sedated | Group A; Sleep efficiency, mean (SD): Arousal index, mean (SD): Group B; Sleep efficiency, mean (SD): Arousal index, mean (SD) | PAV+base 99 (2); PAVhigh 98 (5); |
Alexopoulou et al[86], 2013 | Single centre, randomised,cross over study | 14 | Alternating 4-h blocks over 24 h of: | Free from sedation and opioids for 24 h | Sleep efficiency, median [IQR]: Arousal index, median [IQR] | PAV+ 51 [13-66]; PSV 27 [6-22]; PAV+ 11 [4-25]; PSV 12 [3-16]; No statistically significant improvement found with PAV+ | |
PSV; PS maintained at pre-study level | PAV+; % of unloading set to achieve a mean inspiratory pressure similar to PSV | ||||||
Studies comparing pressure support ventilation against neurally adjusted ventilatory assist | |||||||
Delisle et al[236], 2011 | Single centre, randomised, cross over study | 14 | 2 non-consecutive 4-h blocks (d/night) of: | Free from sedation and opioids for 24 h | Sleep efficiency, median [IQR]: Fragmentation index, median [IQR] | NAVA 74 [52-77]; PSV 44 [29-74]; NAVA 18 [8-22]; PSV 34 [25-54]; NAVA statistically significant improvement in the efficiency and reduced fragmentation of sleep | |
PSV; PS to achieve Vt 8 mL/kg; RR < 35/min | NAVA |
Table 3 Comparison of American Academy of Sleep Medicine’s and Rechtschaffen and Kales criteria sleep stage nomenclature
AASM | R&K | |
Wake | Stage W | Stage W |
NREM sleep | Stage N1 | Stage 1 |
Stage N2 | Stage 2 | |
Stage N3 | Stage 3 | |
Stage 4 | ||
REM sleep | Stage R | Stage REM |
Table 4 Summary of objective methods of sleep measurement in the critically ill
Method | Benefits | Limitations |
Full polysomnography (PSG) | Gold standard technique; Provides polygraphic data on EEG, eye movements and chin tone; Established guidelines for interpreting data for normal sleep | Complex set up; Relatively expensive; Poorly tolerated in 25% of patients; Interferes with nursing care; May interfere with patient sleep; Interpretation requires sleep specialist; No validated criteria for atypical EEG found commonly in critically ill |
Bispectral index (BIS) monitor | Small anatomic footprint; Simplified set up compared to PSG; Does not require sleep specialist for interpretation; Less affected by atypical EEG common in critically ill | Inaccurate differentiation of REM from N1/N2 sleep; Correlates weakly with RCSQ; No validated criteria for interpretation of results; Primarily designed to monitor depth of sedation |
Limited lead EEG | Small anatomic footprint; Simplified set up compared to PSG; May not require sleep specialist for interpretation | Accuracy dependent on device and auto-staging software; Interpretation dependent on sleep specialist if not using auto-staging |
Actigraphy | Minimally invasive; Simple set up; Easy to perform serial measures; Established use in outpatient setting | Poor accuracy compared to PSG and nurse observation, including over-estimation of total sleep time and sleep efficiency; Confounded by immobility, weakness, sedation, and neurological injury |
Under mattress sensor | Non-invasive modality; Simple set up | Moderate agreement, but poor specificity compared to PSG; No correlation with RCSQ |
Table 5 Summary of randomised clinical trials assessing nocturnal melatonin as a pharmacological sleep aid
Ref. | Design | Patients | Intervention & control | Sedation | Outcome |
Ibrahim et al[158], 2006 | Single centre, double-blind, randomised trial | 32 pts | I: Melatonin 4 mg; C: placebo; For ≥ 48 h | Infusions ceased for ≥ 12 h | No significant difference in total sleep time by modified SOT |
Bourne et al[136], 2008 | Single centre, double-blind, randomised trial | 24 pts | I: Melatonin 10 mg; C: Placebo; For 4 nights | Ceased for ≥ 30 h | No significant difference in total RCSQ or sleep efficiency by BIS |
Foreman et al[222], 2015 | Single centre, pilot, randomised trial | 12 pts | I: Melatonin 3 mg plus eye masks and headphonesC: Standard care; For 1-7 d | Propofol allowed. Opiates ceased > 24 h | Primary outcome not determined in 65% due to uninterpretable PSG |
Mistraletti et al[221], 2015 | Single centre, double-blind, randomised trial | 82 pts | I: Melatonin 3+3 mg; C: Placebo; From day 3 of ICU until ICU discharge | Enteral hydroxyzine and lorazepam allowed | No significant difference in total sleep time by nurse observation |
Gandolfi et al[224], 2020 | Double centre, double-blind, randomised trial | 203 pts | I: Melatonin 10 mg; C: Placebo For 7 d or until hospital discharge | As per treating clinician | Statistically improved total RCSQ, mean (SD): I: 61 (26) C: 70 (21) (P = 0.03); No significant difference in total sleep time by nurse observation |
Wibrow et al[225], 2021 | Multicentre (12), double blind, randomised, trial | 841 pts | I: Melatonin 4 mg; C: Placebo; For 14 d or until ICU discharge | As per treating clinician | No significant difference in total RCSQ |
- Citation: Showler L, Ali Abdelhamid Y, Goldin J, Deane AM. Sleep during and following critical illness: A narrative review. World J Crit Care Med 2023; 12(3): 92-115
- URL: https://www.wjgnet.com/2220-3141/full/v12/i3/92.htm
- DOI: https://dx.doi.org/10.5492/wjccm.v12.i3.92