Documenting Rapid Response System afferent limb failure and associated patient outcomes

Abstract

Objective: Describe afferent limb failure (ALF), defined as documented Rapid Response System (RRS) calling criteria, but no associated call, in the 24h prior to an event.

Methods: Retrospective medical record and database review. Adult in-patients whose hospital length of stay (LOS) was greater than 24h, an event being a cardiac arrest, Medical Emergency Team (MET) call or unanticipated Intensive Care Unit (ICU) admission.

Results: Over 6 months, there were 443 patients with 575 events, of which 35 (6.1%) were cardiac arrests, 395 (68.7%) MET calls, and 145 (25.2%) ICU admissions. 131 (22.8%) events had documented ALF, of which 47/131 (35.9%) had documented criteria across more than one time period. Patients with ALF, compared to those without ALF, were significantly more likely to have an unanticipated ICU admission (45/131 (34.4%) vs 100/443 (22.5%), p=0.01), but be of similar age (71 years vs 72 years, p=0.44), male gender (51.1% vs 53.2%, p=0.38), APACHE 2 score (22.8 vs 21.4, p=0.67), predicted risk of death (0.394 vs 0.367, p=0.55), ICU LOS (2 days vs 2 days, p=0.56), likelihood of not-for-resuscitation order during an event (4/131 (3.4%) vs 22/444 (5.0%), p=0.34), and hospital mortality (42/107 (39.3%) vs 125/236 (37.2%), p=0.70). Hospital mortality for patients with ALF across multiple, compared to single time periods was higher, 21/40 (52.5%) vs 22/69 (31.9%), p=0.03.

Conclusions: RRS ALF is a useful performance measure for a mature RRS, and is associated with unanticipated ICU admissions. The duration of, and not timing of, ALF criterion occurrence may affect hospital mortality.