1142: THE APPROPRIATE USE OF CHEST CT ANGIOGRAPHY IN PULMONARY EMBOLISM A ONE-YEAR RETROSPECTIVE ANALYSIS

Abstract

Learning Objectives: We aim to evaluate the effectiveness and appropriateness of CT chest angiography (CTA) study in diagnosing pulmonary embolism and to determine the incidence of Contrast induced nephropathy after CTA exposure. Methods: This is a retrospective observational single-center based study where we carried out chart review of patients receiving CTA during one-year period, March 2013 to March 2014, at a university affiliated community teaching hospital, Chicago, Illinois, USA. Sample size was estimated to be 428 charts using OpenEpi Version 3. After IRB approval, we applied exclusion criteria’s and inclusion criteria’s and risk-stratified them using Revised Geneva scoring. Inclusion criteria were CTA done at emergency department or as inpatient, and age >18 years. Exclusion criteria were ICU admission (mean arterial pressure <60mmHg, CTA done as outpatient test, end-stage renal disease patients on dialysis, up-trending creatinine before CTA was done, patients discharged or expired <48 hours after CTA. Serum Creatinine (SCr) was reviewed in first 24 hours before CTA, which was established as baseline, and CIN was defined as 25% increase in SCr from baseline within 48 hours after procedure. Data was gathered and analyzed using Microsoft Excel and Access. Results: Among 428 of patients enrolled, only 382 met the inclusion criteria. Of all the patients that received CTA, 107 (28%) had low pretest probability, 259 (67%) had intermediate probability, and 16 (4%) has high pretest probability. PE was found in only 52 patients (13.6%), of which, 5 patients (31%) were from high risk group, 37 patients (14%) is from intermediate risk group, and 10 patients (9%) were from low risk groups. D-Dimer was done in 147 (40%) of those with low risk and intermediate risk. Overall incidence of CIN was 25 (6.5%) Conclusions: PE is one of the leading causes of in-patient mortality. Even though risk stratification scoring systems exist, compliance with these guidelines varies among institutions and we often expose patients to radiation as well as contrast related risks. Given the incidence of CIN and yield of positive PE results in patients receiving CTA, it is evident that scoring systems should be used to screen for pretest probability first. This will reduce the disproportionate number of patients exposed to IV contrast and also cost-effective. An alternative approach is to establish protocols to lower the dose of contrast used in CTA to prevent CIN especially in those patients with pre-existing renal impairment.