Exit block in the intensive care unit

To the Editor:

Intensive care is a finite and costly resource with nine beds per 100 000 population in Australia and at a cost of $4000 per bed-day. From 1999, the demand for intensive care unit (ICU) beds has increased at an average rate of 2.5% annually.1,2 Faced with increased demand and capacity restraints, fiscal sustainability is dependent on efficient use of limited ICU resources.

ICU bed availability varies significantly across countries and creates a threshold for clinicians to admit patients.3 The availability of beds may be influenced by the number of patients well enough for ward discharge but who are exit blocked. ICU access block is a significant safety concern for critically ill patients, and ICU exit block (the inability to discharge a patient who is medically fit for discharge) may contribute significantly to ICU access block.4,5

Using a single-day point prevalence study, we obtained an estimate for ICU exit block in 39 Australian and ten New Zealand adult ICUs in 2014. Across all sites, 13% (median value of exit block across the sample hospitals, 8.1%; interquartile range, 0–23%) of patients in the ICU on the study day were awaiting a ward bed. Patients in Australian ICUs were twice as likely to be exit blocked compared with patients in New Zealand ICUs (14.9% v 7.6%). Hospital and ICU size and location (rural v metropolitan) did not influence levels of exit block, but ICUs with > 80% occupancy had higher levels of exit block (Box).

Our results were similar to those of the 2007–14 Australian Council on Healthcare Standards clinical indicator report, which found that about 25% of ICU discharges were delayed for more than 6 hours.5 Using an ICU bed for a patient who no longer needs it represents an inefficient use of resources and risks creating delays in admitting other acutely unwell patients.

In the emergency department setting, we have seen the 4-hour rule improve hospital access and outcomes by prioritising transfer of emergency department patients to ward beds. Monitoring ICU access and exit block provides a comparable metric for understanding the effects of prohibiting ICU patient flow and for determining how to safely and efficiently allocate limited resources for critically ill patients.