Echocardiography, not chest radiography, for evaluation of cannula placement during pediatric extracorporeal membrane oxygenation

Abstract

Objective: Optimal cannula position is essential during extracorporeal membrane oxygenation (ECMO). We hypothesize that echocardiography is superior to chest radiography in diagnosing abnormal cannula position during ECMO.

Design: Retrospective.

Setting: Pediatric hospital.

Patients: 100 pediatric patients requiring ECMO.

Measurements and main results: We reviewed the medical records of all ECMO patients (n = 100), including reports of all echocardiograms (n = 326), during the years 2002-2004. Of the 91 patients who had echocardiograms while on ECMO, 33 had at least 1 echocardiogram for cannula-position evaluation. Of the remaining 58 patients with echocardiograms for reasons other than cannula-position evaluation, 4 (7%) were found to have abnormal cannula position. These included arterial cannula (AC) within 2-4 mm of the aortic valve (n = 2), AC across the aortic valve into the left ventricle (n = 1), and venous cannula (VC) abutting the atrial septum (n = 1). Of the 33 patients with echocardiograms for evaluation of cannula position, 8 (24%) required intervention. Of those 8 patients, 4 required cannula repositioning due to VC in the coronary sinus (n = 1), VC abutting atrial septum (n = 1), AC in left subclavian artery (n = 1), and AC within 3 mm of aortic valve (n = 1). The remaining 4 with normal cannula position required upsizing of the VC (n = 2), increased circuit flow (n = 1), or intravascular volume administration (n = 1). Overall, 12 of 91 patients (13%) required intervention based on echocardiographic findings. Chest radiography did not detect abnormalities of ECMO cannula position in any of the 8 patients with this problem, nor were any additional patients with abnormal cannula position identified by chest radiography.

Conclusions: Echocardiography appears to be superior to chest radiography for assessing ECMO cannula position in our institution. A prospective study, including cost analysis, comparing chest radiography and echocardiography, is needed to definitely determine the preferred diagnostic test or sequence of tests to establish ECMO cannula position.