Point-of-Care Echocardiography in the Difficult-to-Image Patient in the ICU: A Narrative Review

Abstract

Objectives: The objective of this narrative review was to address common obstacles encountered in the ICU to acquiring quality and interpretable images using point-of-care echocardiography.

Data sources: Detailed searches were performed using PubMed and Ovid Medline using medical subject headings and keywords on topics related to patient positioning, IV echo contrast, alternative subcostal views, right ventricular outflow tract (RVOT) hemodynamics, and point-of-care transesophageal echocardiography. Articles known to the authors were also selected based on expert opinion.

Study selection: Articles specific to patient positioning, IV echo contrast, alternative subcostal views, RVOT hemodynamics, and point-of-care transesophageal echocardiography were considered.

Data extraction: One author screened titles and extracted relevant data while two separate authors independently reviewed selected articles.

Data synthesis: Impediments to acquiring quality and interpretable images in critically ill patients are common. Notably, body habitus, intra-abdominal hypertension, dressings or drainage tubes, postoperative sternotomies, invasive mechanical ventilation, and the presence of subcutaneous emphysema or lung hyperinflation are commonly encountered obstacles in transthoracic image acquisition in the ICU. Despite these obstacles, the bedside clinician may use obstacle-specific maneuvers to enhance image acquisition. These may include altering patient positioning, respiratory cycle timing, expanding the subcostal window to include multilevel short-axis views for use in the assessment of RV systolic function and hemodynamics, coronal transhepatic view of the inferior vena cava, and finally point-of-care transesophageal echocardiography.

Conclusions: Despite common obstacles to point-of-care echocardiography in critically ill patients, the beside sonographer may take an obstacle-specific stepwise approach to enhance image acquisition in difficult-to-image patients.

Keywords: critical care; hemodynamics; transesophageal echocardiography; transthoracic echocardiography; ultrasound.

Figure 1.

Schematic illustrating commonly encountered obstacles to transthoracic echocardiography. COPD = chronic obstructive pulmonary disease. Created with Biorender.com.

Figure 2.

Schematic illustrating maneuvers to improve image acquisition by specific obstacles. IVC = inferior vena cava, RVOT VTI = velocity time integral of the right ventricular outflow tract, SAX = short axis, TEE = transesophageal echocardiography.

Figure 3.

Point-of-care ultrasonography (POCUS) images displaying: (A) Calculation of subcostal echocardiographic assessment of tricuspid annular kick (SEATAK) from the subcostal short-axis (SAX) view, which is calculated by placing M-mode over the tricuspid annulus in a SAX view from the subcostal window and measuring excursion, (B) Estimation of tricuspid annular plane systolic excursion (TAPSE) from the subcostal four-chamber view by measuring the distance between the tricuspid annulus in diastole and systole. RA = right atrium, RV = right ventricle.

Figure 4.

Schematic illustrating angle of insonation and fanning direction to obtain subcostal SAX views. Arrows indicate direction of fanning moving from papillary muscle level to aortic valve level. Created with Biorender.com.

Figure 5.

Point-of-care ultrasonography (POCUS) images displaying: (A) parasternal short-axis (SAX) aortic valve (AoV)/right ventricular outflow tract (RVOT) view, (B) subcostal SAX AoV/RVOT view, (C) subcostal SAX AoV/RVOT view with color-flow Doppler displaying flow away from the transducer through the RVOT, (D) calculation of RVOT velocity time integral (VTI) from the subcostal SAX AoV/RVOT view. LA = left atrium, PA = pulmonary artery, PV = pulmonic valve, RA = right atrium, RV = right ventricle, TV = tricuspid valve.

Figure 6.

Point-of-care ultrasonography (POCUS) images displaying: (A) subcostal bicaval view, (B) right midaxillary line transhepatic coronal inferior vena cava (IVC) view. ECMO = extracorporeal membrane oxygenation, LA = left atrium, LV = left ventricle, LVOT = left ventricular outflow tract, OxyRVAD = right ventricular assist device with membrane oxygenator, RA = right atrium, RV = right ventricle, SVC = superior vena cava.