Point-of-care ultrasound in diagnosis and management of congestive nephropathy

Abstract

Congestive nephropathy is kidney dysfunction caused by the impact of elevated venous pressures on renal hemodynamics. As a part of cardiorenal syndrome, the diagnosis is usually made based on history and physical examination, with findings such as jugular venous distension, a third heart sound, and vital signs as supporting findings. More recently, however, these once though objective measures have come under scrutiny for their accuracy. At the same time, bedside ultrasound has increased in popularity and is routinely being used by clinicians to take some of the guess work out of making the diagnosis of volume overload and venous congestion. In this mini-review, we will discuss some of the traditional methods used to measure venous congestion, describe the role of point-of-care ultrasound and how it can ameliorate a clinician's evaluation, and offer a description of venous excess ultrasound score, a relatively novel scoring technique used to objectively quantify congestion. While there is a paucity of published large scale clinical trials evaluating the potential benefit of ultrasonography in venous congestion compared to gold standard invasive measurements, more study is underway to solidify the role of this objective measure in daily clinical practice.

Keywords: Congestion; Doppler; Heart failure; Hemodynamics; Nephrology; Point-of-care ultrasonography; Ultrasound; Venous excess ultrasound score.

Figure 1

Lung ultrasound images. A: Normal lung showing horizontal artifacts, i.e., A-lines (arrows); B: Vertical artifacts (arrows) known as B-lines indicating interlobular septal thickening, typically seen in congestion; C: Pleural effusion (asterisk) as seen on lateral scan; D: Right pleural effusion (asterisk) as seen from subxiphoid scanning window. IVC: Inferior vena cava.

Figure 2

Venous excess ultrasound grading. When the diameter of the inferior vena cava is > 2 cm, three grades of congestion are defined based on the severity of abnormalities on hepatic, portal, and renal parenchymal venous Doppler. Hepatic vein Doppler is considered mildly abnormal when the systolic (S) wave is smaller than the diastolic (D) wave, but still below the baseline; it is considered severely abnormal when the S-wave is reversed. Portal vein Doppler is considered mildly abnormal when the pulsatility is 30% to 50%, and severely abnormal when it is ≥ 50%. Asterisks represent points of pulsatility measurement. Renal parenchymal vein Doppler is mildly abnormal when it is pulsatile with distinct S and D components, and severely abnormal when it is monophasic with D-only pattern. Figure adapted from NephroPOCUS.com with permission.

Figure 3

Doppler components of extended venous excess ultrasound score examination. Figure adapted from NephroPOCUS.com with permission.

Figure 4

The chain of venous congestion: Apical view of the heart is shown in the upper left corner where bulging of the interatrial septum into the left atrium can be noted suggestive of high right atrial pressure. Next image shows significantly dilated internal jugular vein followed by a plethoric inferior vena cava. Lower panel represents the commonly assessed Doppler parameters to assess systemic venous congestion, all of which are severely abnormal. Please see Figure 3 for the normal appearance of these waveforms and Figure 2 for venous excess ultrasound score grading. RA: Right atrium; RV: Right ventricle; LA: Left atrium; LV: Left ventricle; CA: Carotid artery; S: Systolic wave; D: Diastolic wave.