Volume 194 - Issue 11
Increased mortality associated with after-hours and weekend admission to the intensive care unit: a retrospective analysis
Authors: Dev A S Kevat, Andrew R Davies, Peter A Cameron and Shantha M W Rajaratnam
Med J Aust 2011; 194 (11): 616. || doi: 10.5694/j.1326-5377.2011.tb03126.x
Published online: 6 June 2011
Published online: 6 June 2011
To the Editor: We read with interest the recent cover article by Bhonagiri and colleagues detailing increased standardised mortality rates for patients admitted to Australian intensive care units (ICUs) out of hours.1 Have the authors considered a secondary analysis controlling for night-time staffing ratios? Aside from staffing levels, human factors such as the effects of fatigue and sleepiness due to circadian rhythm misalignment and sleep deprivation should be considered and further investigated.
Studies have consistently shown that human cognitive and motor performance is substantially worse at night than during the day,2 due to the influence of the endogenous circadian clock. A recent study of emergency medicine registrars at an Australian tertiary hospital showed a 21% decrease in performance at night, in clinical scenarios of fellowship examination standard.3
Sleep during the day is of poorer quality and shorter duration than sleep during the night,4 resulting in chronic sleep restriction that exacerbates the impairment occurring in night work.5 Consecutive night shifts are associated with an increasing risk of accidents and injuries.6 In doctors, including consultants, inadequate sleep (fewer than 6 hours) is associated with harmful effects on patient outcomes.7
Despite our cultural beliefs, doctors are likely to suffer from the same biological effects of sleep loss and circadian rhythm disturbance as suffered by other humans. ICUs may provide one of the best hospital environments in which to study medical error, because of defined and limited personnel compared with non-ICU ward areas. ICUs also usually have better record-keeping and error-recognition systems, because of higher staff:patient ratios.
Possible risk mitigation strategies include increasing the number of night staff, implementing oversight mechanisms for specified procedures and decisions, and ensuring that rosters and shift lengths are designed according to evidence linking sleep disturbance with poor patient outcomes. Such evidence should form the basis of any regulatory frameworks.
References
- Bhonagiri D, Pilcher DV, Bailey MJ. Increased mortality associated with after-hours and weekend admission to the intensive care unit: a retrospective analysis. Med J Aust 2011; 194: 287-292. 0_CBBJAEAE
- Rajaratnam SM, Arendt J. Health in a 24-h society. Lancet 2001; 358: 999-1005. 0_CBBGCBIF
- Marcus L, Liew D, Knott J. The effect of nightshift on emergency registrars’ clinical skills. Emerg Med Australas 2010; 22: 211-215. 0_CBBJGGIE
- Dijk DJ, Czeisler CA. Contribution of the circadian pacemaker and the sleep homeostat to sleep propensity, sleep structure, electroencephalographic slow waves, and sleep spindle activity in humans. J Neurosci 1995; 15: 3526-3538. 0_CBBDBBGE
- Cohen DA, Wang W, Wyatt JK, et al. Uncovering residual effects of chronic sleep loss on human performance. Sci Transl Med 2010; 2: 14ra3. ref5
- Folkard S, Tucker P. Shift work, safety and productivity. Occup Med (Lond) 2003; 53: 95-101. 0_CBBGGAJG
- Rothschild JM, Keohane CA, Rogers S, et al. Risks of complications by attending physicians after performing nighttime procedures. JAMA 2009; 302: 1565-1572. 0_CBBCHIJC