Hyperlactatemia on ICU admission : Comparison between direct admissions and inpatient transfers

Hyperlactatemia is associated with increased mortality. Possible differences between patients directly admitted via the emergency department to the intensive care unit (ICU) and inpatient transfers to the ICU have not yet been investigated.

In this retrospective analysis, characteristics and outcomes between critically ill medical inpatient transfers and direct admissions with hyperlactatemia on ICU admission, defined as a blood lactate >2 mmol/l, were compared.

A total of 1042 patients were included, with 424 inpatient transfers and 618 direct admissions. The median age of inpatient transfers and direct admissions was 67.0 and 70.5 years, respectively (P = 0.03). The median APACHE II score was 25 for inpatient transfers and 23 for direct admissions (P = 0.01). The median blood lactate on ICU admission for inpatient transfers and direct admissions was similar (3.6 vs. 3.5 mmol/l). Sepsis was more common among inpatient transfers than direct admissions (53.5 vs. 31.6%, P = 0.001). The ICU (39.6 vs. 28.8%, P < 0.001), hospital (56.8 vs. 38.3%, P < 0.001) and 28-day mortality (46.5 vs. 35.4%, P < 0.001) was significantly higher for inpatient transfers than direct admissions. Among the sepsis cohort, inpatient transfer, APACHE II score and elevated blood lactate were independent predictors of ICU mortality.

Among medical ICU patients with admission hyperlactatemia, the median blood lactate was not significantly different between direct admissions and inpatient referrals. Inpatients with sepsis may have been referred to the ICU late.