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Intensive nursing work schedules and the risk of hypoglycaemia in critically ill patients who are receiving intravenous insulin
  1. Kimberley Louie1,
  2. Rupi Cheema2,
  3. Peter Dodek1,3,4,
  4. Hubert Wong4,
  5. Amanda Wilmer1,
  6. Maja Grubisic4,
  7. John Mark FitzGerald5,
  8. Najib T Ayas1,2,3,5
  1. 1Program in Critical Care Medicine, Providence Health Care, University of British Columbia, Vancouver, Canada
  2. 2Sleep Disorders Program, University of British Columbia Hospital, Vancouver, Canada
  3. 3Critical Care Division, Department of Medicine, University of British Columbia, Vancouver, Canada
  4. 4Center for Health Evaluation and Outcome Sciences, Providence Health Care, Vancouver, Canada
  5. 5Centre for Clinical Epidemiology and Evaluation, Vancouver Coastal Health Research Institute, Vancouver, Canada
  1. Correspondence to Dr Najib Ayas, Room 224 Comox Building, 1081 Burrard Street, Vancouver, BC V6Z 1Y6 Canada; nayas{at}


Rationale Nurses in the intensive care unit (ICU) commonly work frequent 12 h shifts, potentially leading to fatigue and reduced vigilance. The authors hypothesised that rates of hypoglycaemia in patients receiving an insulin infusion would be associated with the intensity of work of the bedside nurse in the preceding 72 h.

Methods The authors identified ICU patients who had hypoglycaemia (glucose ≤3.5 mmol/l, 63 mg/dl) between October 2006 and June 2007. The number of shifts worked in the previous 72 h was calculated for the nurse caring for the patient when the event occurred (case shift). For each case shift, the authors identified up to three control shifts (24, 48 and 72 h before the event in the same patient) and calculated the number of shifts worked by nurses on these shifts in the previous 72 h. Conditional logistic regression was used to determine whether the number of shifts worked was associated with hypoglycaemia.

Results There were 41 events (32 patients). Each additional shift worked in the previous 72 h was associated with a significantly increased risk of hypoglycaemia (OR=1.65/shift, 95% CI 1.01 to 2.68, p=0.04) after controlling for nurse age and experience. The association was greater for the 23 events associated with an error in management according to the insulin protocol (OR=2.93/shift, 1.15 to 7.44, p=0.02) compared with events not associated with an error (OR=1.34/shift, 0.73 to 2.45, p=0.34).

Conclusions Intensive nursing work schedules are associated with hypoglycaemic events in ICU patients.

  • Healthcare quality
  • human factors
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  • Funding This work was funded by a Michael Smith Foundation for Health Research (MSFHR) Infrastructure Grant (ICU Patient Safety). NTA was supported by a MSFHR Scholar Award and an Established Clinician Scientist Award from the Vancouver Coastal Health Research Institute. JMF was supported by a MSFHR Distinguished Scholar Award.

  • Competing interests None.

  • Ethics approval Ethics approval was provided by the University of British Columbia IRB.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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