Accuracy of emergency physician–directed focused echocardiography in the evaluation of the critically III pediatric patient

Abstract

Study objectives: Echocardiography can be a rapid, noninvasive, objective tool in the assessment of ventricular function and preload during resuscitation of a critically ill or injured child. We seek to determine the accuracy of bedside limited echocardiography by the emergency physician (BLEEP) in estimation of left ventricular function (LVF) and inferior vena cava (IVC) volume as an indirect measure of preload. Methods: We conducted a prospective observational study of a convenience sample of patients admitted to our ICU. A single emergency physician investigator performed all BLEEP examinations using a Sonosite Titan ultrasonographic machine with a variable frequency convex probe. All patients underwent an independent formal echocardiogram by an experienced pediatric echocardiography provider within 60 minutes of the BLEEP examination. IVC volume was assessed by measurement of the maximal diameter of the IVC just caudad to the hepatic vein confluence on the subxiphoid transverse view. LVF was determined by calculating the shortening fraction using M mode measurements on the parasternal short axis view at the level of the papillary muscle. An independent blinded pediatric cardiologist reviewed all images for accuracy and quality. Estimates of shortening fraction obtained on the BLEEP examination were compared with those obtained by the pediatric echocardiography provider. Concordance or agreement between the emergency physician and pediatric echocardiography provider for the measurement of the shortening fraction and IVC diameter was determined using the Pearson correlation coefficient. A P value less than .05 was considered statistically significant. Paired t test was used to compare the magnitude of the difference in measurement of the shortening fraction and IVC by the emergency physician and pediatric echocardiography provider. The proportion of images obtained by the emergency physician (2-dimensional image, M mode, and IVC) that were assessed to be of quality by the cardiologist was determined. A comparison between the proportions of unacceptable images between the groups was estimated using the McNemar test. Results: Thirty-one patients were enrolled. The mean age was 5.1 years (range 23 days to 16 years); 48.4% (15/31) were female patients; 58.1% (18/31) were on mechanical ventilatory support at their study. There was good agreement between the emergency physician and the pediatric echocardiography provider for estimation of shortening fraction ( r =0.78, P P =.003). Similarly, there was good agreement between the emergency physician and pediatric echocardiography provider for estimation of IVC volume ( r =0.8, P P =.14). All the parasternal short axis 2-dimensional images obtained by the emergency physician were of acceptable or higher quality. The proportion of M mode and IVC images that were of quality was 9.6% (3/31) and 3.2% (1/31), respectively. This difference in proportions was not statistically significant ( P =.32). Conclusion: Our study suggests that pediatric emergency physician sonographers are capable of obtaining images that permit accurate assessment of LVF and IVC volume. BLEEP can be performed with focused training and oversight by a pediatric cardiologist.