Intensive nursing work schedules and the risk of hypoglycaemia in critically ill patients who are receiving intravenous insulin.

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.