Objective: To investigate the impact of a new assessment question in the Medical Priority Dispatch System (MPDS) seizure protocol on the ability of the Emergency Medical Dispatchers (EMDs) to identify the presence of agonal or ineffective breathing.
Methods: A retrospective comparative study was conducted using two datasets-each representing two versions of the MPDS protocols (version 10.4 and version 11.2) at the London Ambulance Service (LAS). The "before" dataset (April 2004 to March 2005, version 10.4) did not have a specific assessment Key Question to identify the presence of irregular/agonal breathing. The question was added in the "after" dataset (April 2005 to March 2006, version 11.2). The datasets comprised the number of patients, calls, responses, incidents, and outcome (i.e., cardiac arrest [CA] and blue-in [BI]) parameters categorized using MPDS determinant codes. A distribution of these parameters was stratified by protocol version. Two-by-two contingency tables to determine association between ("before" and "after") protocols and CA outcome were generated. The likelihood of classifying CA outcome under the "Not fitting now and breathing regularly (verified)"-protocol 12 ALPHA-level 1 (12-A-1) and combined DELTA descriptor codes, was established. Odds ratios (OR) and p-values at significance level of 0.05 cut-off were used to determine any significant associations.
Results: For both datasets, the percentage of the emergency parameters increased with increasing determinant level from ALPHA to DELTA. The percentage of CA outcome in the 12-A-1 descriptor code in protocol version 11.2 was lower than that in version 10.4 (0.18% vs. 0.24%). Within protocol version 11.2, CA outcome was twice more likely in the combined DELTA descriptor codes when compared to other protocol 12 descriptor codes (OR(95%CI): 2.10(1.30, 1.40), p=0.002).
Conclusions: The addition of the new assessment question for "breathing regularly" to the dispatch question sequence in the MPDS seizure protocol provides a valuable tool for identifying true cardiac arrest patients. Most of these cases appeared to be specifically captured by the new code 12 DELTA-level 3 (12-D-3): "Irregular Breathing".