Characteristics and outcomes of patients admitted to ICU following activation of the medical emergency team : impact of introducing a two-tier response system

Objective: To determine the impact of introducing a two-tier system for responding to deteriorating ward patients on ICU admissions after medical emergency team review. Design: Retrospective database review before (2006-2009) and after (2011-2013) the introduction of a two-tier system. Setting: Tertiary, university-affiliated hospital. Patients: A total of 1,564 ICU admissions. Interventions: Two-tier rapid response system. Measurements and Main Results: The median number of medical emergency team activations/1,000 hospitalizations increased from 22 to 31 (difference [95% CI], 9 [5-10]; p < 0.0001) with a decreased rate of medical emergency team activations leading to ICU admission (from median 11 to 8; difference [95% CI], 3 [3-4]; p = 0.03). The median proportion of medical emergency team reviews leading to ICU admission increased for those triggered by tachypnoea (from 11% to 15%; difference [95% CI], 4 [3-5]; p < 0.0001) and by hypotension (from 27% to 43%; difference [95% CI], 15 [12-19]; p < 0.0001) and decreased for those triggered by reduced level of consciousness (from 20% to 17%; difference [95% CI], 3 [2-4]; p < 0.0001) and by clinical concern (from 18% to 9%; difference [95% CI], 10 [9-13]; p< 0.0001). The proportions of ICU admissions following medical emergency team review did not change significantly for tachycardia, seizure, or cardiorespiratory arrest. The overall ICU mortality for admissions following medical emergency team review for tachypnoea, tachycardia, and clinical concern decreased (from 29% to 9%: difference [95% CI], 20 [11-29]; p < 0.0001) but did not change for the other triggers. The Acute Physiology and Chronic Health Evaluation predicted and observed ICU mortality and the proportion of patients dying with a not-for-resuscitation order decreased. Conclusions: The introduction of a two-tier response to clinical deterioration increased ICU admissions triggered by cardiorespiratory criteria, whereas admissions triggered by more subjective criteria decreased. The overall ICU mortality for patients admitted following medical emergency team review decreased, suggesting that the two-tier system led to earlier recognition of reversible pathology or a decision not to escalate the level of care.