Evaluation of calling criteria for the rapid response system utilising single versus multiple physiological parameter disturbances.

Background: The Adult Deterioration Detection System for Medical Emergency Team (MET) activation is widely used and includes single parameter (SP-MET) and multiple parameter (MP-MET) disturbances. Whether the patient characteristics, interventions and outcomes differ for SP-MET compared with MP-MET is uncertain.

Aims: To describe MET interventions and outcomes of SP versus MP MET in the Acute Medical Unit (AMU) of a tertiary care hospital.

Methods: Retrospective audit over 6 months comparing SP-MET and MP-MET groups.

Results: SP-MET constituted 64.1% (168) of 262 AMU MET calls, most commonly for hypotension (35.5%) and tachycardia (14.1%). There were no significant differences in demographic and disease characteristics between the two groups. Common interventions included fluid/electrolyte replacement in 139 (52%), oxygen therapy in 46 (17%) and non-invasive ventilation in 33 (13%) patients. After MET intervention, 82.4% patients stayed on the ward, 8.4% died/were palliated, 6.5% were transferred to the Intensive Care Unit (ICU) and 2.7% patients required urgent transfer to the theatre for intervention. SP-MET patients were more likely to remain on the ward (88.7% vs 71.3%; P = 0.001), receive ward-based interventions (85.1% vs 61.7%; P < 0.001) and less likely to experience death/palliation (4.2% vs 16%, P = 0.001) compared with the MP-MET group. MP-MET were independently associated with negative outcomes (OR 3.10; 95% CI 1.60-6.00).

Conclusion: SP-MET identify a cohort of patients at lower risk of requiring escalation of care and ICU admission. Given the resource intensity of MET activation, further research is warranted to determine whether alternative response strategies are appropriate for selected SP disturbances.