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146 P R I N C I P L E S A N D P R A C T I C E O F C R I T I C A L C A R E

sleep, that lasts 60–90 minutes. Time spent awake during critical care. Actigraphy is another method of recording
the sleep period is less than 5% of TST. 123 All sleep stages sleep that has been attempted in the critically ill. Modern
are important to health and unfortunately critically actigraphs are small wristwatch devices (they may also be
ill patients commonly experience very little deep or located on the trunk or leg) containing accelerometers
REM sleep. that detect motion in a single axis or multiple axes. 127,128
Data obtained from actigraphy provides an over-
There are changes in sleep architecture over the adult
lifespan which require consideration in the context of estimation of sleep time (critically patients are typically
critical care nursing. TST and percentage of SWS decline immobile for long periods regardless of sleep state). The
(TST by 10 minutes and SWS by 2% per decade) and light other objective method which has been attempted in
129,130
sleep increases slightly (only by 5% between 20 and 70 critical care is BIS monitoring. At present, consider-
years) with age. 124 REM sleep remains fairly constant with able algorithm development using comparisons with
an approximate 0.6% decline per decade until age 70 PSG data are required before it is a viable option to
when REM increases with a simultaneous decrease in measure sleep accurately in any setting.
TST. 125 Time spent awake after sleep onset increases with The most reliable option for the critical care clinician to
age by 10 minutes per decade after age 30. 124 assess sleep is a patient self-report (in any case the patient
is best placed to judge the quantity and quality of
their sleep if they are able). Two instruments have been
SLEEP ASSESSMENT/MONITORING specifically developed for use in critical care; the Richards-
131
An assessment of the patient’s sleep history should be Campbell Sleep Questionnaire (RCSQ) and the Sleep
118
performed as soon as possible after admission. The in Intensive Care Questionnaire (SICQ). The RCSQ
person closest to the patient (ideally living in the same comprises five 100mm visual analogue scales (VAS): sleep
home) may be willing to provide a sleep history if the depth, latency, awakenings, time awake and quality of
patient is unable to communicate verbally. The require- sleep. It was pilot tested in a medical ICU (n = 9, 100%
ment for nocturnal non-invasive ventilation or sleep male) 132 and validated in a more extensive investigation
medication should be conveyed to the medical team for involving 70 male patients. There was a moderate cor-
133
consideration. Particular attention should be paid to relation between total RCSQ score and PSG sleep effi-
reports of daytime sleepiness, dissatisfaction with sleep ciency index (SEI); r = 0.58, (p < 0.001). 133 The SICQ was
and bed partner reports of excessive snoring as this may not validated against polysomnography. Therefore it is
indicate an undiagnosed sleep disorder. Usual sleep better suited for use when assessing a unit/organisation-
habits such as ‘going to bed’, ‘getting up’ and shower wide change in practice rather than for individual patients
times should be accommodated while the patient is (see Table 7.9).
treated in critical care whenever possible.
Up to 50% of all patients treated in critical care may be
Unfortunately, few objective methods of assessing sleep unable to complete a self-assessment of their sleep; in
reliably in the critically ill are available. Polysomnogra- which case the only remaining option is nurse assess-
phy (PSG), a method of recording electroencephalogra- ment. 119,134 The Nurses’ Observation Checklist (NOC) 135
phy, electrooculography and electromyography, is the can be used to obtain the bedside nurses’ assessment of
‘gold standard’ for assessing sleep. PSG data are analysed the quantity of the patient’s sleep. It is a relatively simple
126
according to Rechtschaffen and Kales’ criteria and instrument to use. However, evidence from many studies
provide TST and sleep stage times. However a trained suggests that nurses tend to overestimate sleep time, so
operator is required to ensure satisfactory signal quality, sleep time derived from the NOC may be better used as
continuous recording and interpretation. 123 This draw- a trend rather than a definitive report for an individual
back precludes its routine use in clinical practice in night’s sleep. 134,136-138

TABLE 7.9 Sleep assessment instruments

Instrument Description Comments
Richards Campbell Sleep ● Five visual analogue scales (0–100 mm) ● Patient does not need to able to write (nurse can mark the
Questionnaire 131 ● Total score derived from average of the 5 line as instructed by patient)
scales (high scores indicate good sleep) ● Patient requires sufficient level of cognitive function to use it
Sleep in Intensive Care ● Seven questions (some have more than ● Patient does not need to able to write (nurse can circle the
Questionnaire 118 one item) response as instructed by patient)
● Likert scales 1–10 ● Patient requires sufficient level of cognitive function to use it
● No global score ● Not yet validated
● Good for organisational changes in practice
Nurses’ observation ● Tick box table ● No training required
checklist 135 ● Assignment of a category; ‘awake’, ‘asleep’, ● Typically nurses tend to overestimate sleep
‘could not tell’ and ‘no time to observe’ ● Better for trend over several nights
every 15 minutes.