Intensive care unit occupancy after introduction of the emergency department 4-hour discharge rule at a tertiary referral hospital in Western Australia.

Background: The 4-hour rule has been introduced in Western Australia, requiring that emergency department (ED) patients be admitted to hospital or discharged from the ED within 4 hours of presentation. We hypothesised that this rule might have been associated with changes in medical emergency team (MET) calls and intensive care unit exit bed block.

Methods: Hospital databases were examined to determine compliance with the 4-hour rule, the effect on ICU exit bed block, and the number of MET calls, in 2008 (before introduction of the 4-hour rule) and 2011 (after introduction of the 4-hour rule). We also measured background ICU and hospital activity in 2008 and 2011.

Results: Monthly compliance with the 4-hour rule ranged from 35%-46% in 2008 to 64%-75% in 2011 (P < 0.0001). There was a marked increase in bed block days for patients in the ICU between 2008 (before introduction of the 4-hour rule) and 2011 (after introduction of the 4-hour rule) (P = 0.05). The increase in ICU bed block-days could not be explained by a difference in ICU occupancy, as there was a reduction in ICU bed-days between 2008 and 2011 (P = 0.014). There was a reduction in hospital mortality rate between 2008 and 2011 (P < 0.001). There was no significant increase in the number of MET calls from 2008 to 2011 (P = 0.221). Hospital activity (separations) increased from 2008 to 2011 (P < 0.0001).

Discussion: The introduction of the 4-hour rule was associated with increased exit block from the ICU, but not with increased MET calls to attend to unstable or deteriorating ward patients. Introduction of the 4-hour rule was associated with a small reduction in hospital mortality.