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The timing of new acute hemodynamic events in ICU patients


Whether the day and time of ICU admission or discharge impacts patient care and outcome has been the focus of recent inquiry. There may also be a relationship between timing and outcome for events occurring within the ICU. As a first step to explore this issue, we aimed to describe the timing of new acute hemodynamic events in a large ICU population.


Acute hemodynamic events are equally distributed throughout the day and throughout the week.


From 1 July 1 2000 to 1 June 2001, we prospectively collected data for all ICU patients at the University of Pittsburgh Medical Center, a tertiary care academic medical center with > 120 ICU beds serving medical, surgical, trauma, neurological, and transplant patients. Because we wished to focus on new 'within-ICU' events, we defined an event as the first occurrence of acute hemodynamic instability after > 24 hours in the ICU (to exclude events associated with the initial admission) and > 6 immediately-preceding hours with a cardiovascular SOFA score ≤ 1. We defined acute instability as MAP < 60 mmHg, SBP < 90 mmHg, or a decrease in SBP ≥ 40 mmHg when the prior SBP was < 150 mmHg. We generated event frequency by hour and by day of the week.


There were 5592 patients with an ICU length of stay > 24 hours incurring 6758 ICU admissions. In 1449 (32%) of these patients there was at least one event. Acute hemodynamic events after being in the ICU > 24 hours happened on average on day 3 of the ICU stay. The event frequency did not vary by day of the week (Monday 14.6%, Tuesday 15.9%, Wednesday 13.3%, Thursday 13.5%, Friday 14.8%, Saturday 13.9%, Sunday 14.0%). Although there was a trend to less events in the early morning and evening, event frequency generally varied little by hour of the day (Fig. 1).

Figure 1
figure 1

Distribution of events throughout the day.


New acute hemodynamic events are extremely common in the ICU. They vary little by time of day and day of week. This finding may have important implications for ICU staffing patterns.

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Kersten, A., Clermont, G., Hoste, E. et al. The timing of new acute hemodynamic events in ICU patients. Crit Care 8 (Suppl 1), P76 (2004).

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