Computed tomography pulmonary angiogram as a result of medical emergency team calls: a 5-year retrospective audit.

Objective: To determine the proportion of computed tomography pulmonary angiograms (CTPAs), performed after medical emergency team (MET) calls, that are positive for pulmonary embolism (PE), and whether there are useful clinical predictors of positive CTPA results.

Design: All patients from a tertiary referral hospital in Melbourne who had an MET response and an associated CTPA within 6 hours, from 2009 to 2013, were included. We reviewed medical records to assess indications for CTPA, including MET clinical triggers, time of day of the MET (implying the seniority of decision making), chest x-ray results and Wells scores as a clinical decision rule for PE.

Results: There were 4578 MET responses (in 3136 patients) over the 5-year study period, from which 70 CTPAs were ordered (2.2% of all patients). A PE was identified in 12 patients (17.1%). The median age of CTPA patients was 70 years (interquartile range, 60-76 years) and most were surgical patients (80%). The major MET triggers for CTPA were hypoxia (42.9%) and hypotension (28.6%). An abnormal chest x-ray was associated with a low likelihood of PE. The Wells scores and MET indications of hypoxia, hypotension and tachycardia were not accurate in predicting the presence or extent of PE.

Conclusion: Clinical decision rules and MET indications were not significantly associated with the presence of PE on CTPA. However, an abnormal chest x-ray has a high negative predictive value and therefore may be helpful in preventing unnecessary CTPAs.