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Hemodynamic POCUS in cirrhosis: think beyond the IVC

In nephrology practice, acute kidney injury (AKI) in patients with cirrhosis often poses a diagnostic challenge owing to multitude of etiologic possibilities and overlapping presentations. Most such patients end up receiving empiric intravenous fluids without proper physical examination (i.e., POCUS). With increasing recognition of venous congestion as a hemodynamic phenotype of renal dysfunction and availability of bedside tools such as ultrasound that helps us to diagnose and monitor sequela of fluid overload, there is no justification for blind management. In a recent study, 62% of patients diagnosed with hepatorenal syndrome (HRS) by clinical criteria had elevated cardiac filling pressures; interestingly, their serum creatinine improved with diuretic therapy. This begs for careful evaluation and management of these patients. If we are diagnosing someone with HRS, we are essentially saying they have a condition with worse prognosis than pancreatic cancer, unless they get a liver transplant. So, it’s not something we should leave to guesswork and our internal biases.

Many nephrologists started to express interest in learning IVC POCUS to ‘determine volume status’ in this context, which partly stems from this study where IVC POCUS revealed ‘hidden’ volume disorder in a substantial number of patients diagnosed with HRS based on clinical criteria. Unfortunately, IVC ultrasound is not so easy as it seems in patients with cirrhosis. Especially in cases where the liver is bright (due to fatty change), it can be very difficult to locate the vessels and other landmarks. Moreover, the diameter may not be reliable due to altered liver architecture. In fact, IVC scalloping (narrowing due to caudate lobe hypertrophy/nodularity) is a relatively specific sign for the diagnosis of cirrhosis. In such cases, we don’t know where to measure the diameter and collapsibility of the vessel and if the usual criteria (size </> 2.1 cm, inspiratory collapse </> 50%) are applicable to estimate right atrial pressure (RAP). Examples of scalloping:

In some cases, especially where the IVC is small (due to low RAP or increased intra-abdominal pressure or local anatomy), users with less experience tend to mistake aorta for the IVC. Here are a couple of examples:

In a fair number of patients particularly where repositioning is not possible due to altered mental status or body habitus, it may be impossible to find the IVC. Here is one such example:

When the IVC is not reliable, internal jugular (IJ) vein is a decent alternative to get an idea of the RAP. The vein can be easily located using POCUS and measuring the height of the collapse point provides an estimate of RAP (analogous to the highest point of venous pulsation when assessing JVP by inspection). In the following example, I am sweeping the transducer from the base of the neck to the point where the IJ vein collapses:

As discussed in the previous post, we can also use IJ vein’s response to valsalva maneuver to estimate RAP in spontaneously breathing patients.

How about VExUS? Hepatic and portal veins may not be reliable in patients with cirrhosis and portal hypertension. Do any alternatives exist? Yes, VExUS is essentially evaluation of systemic veins using Doppler. We utilize femoral vein, internal jugular vein, and superior vena cava Doppler where feasible to perform E-VExUS (extended VExUS). Will talk about these components in detail in future posts.

In addition, assessment of the left side of the heart is also very important. Presence of extravascular lung water alerts us of ‘volume intolerance’ irrespective of venous congestion. Similarly, assessing stroke volume at the bedside gives an idea whether a patient with small collapsible IVC has true volume depletion or a high cardiac output state due to splanchnic vasodilation and chronic fluid overload (not at all uncommon in real life). In our recent perspective published in Kidney360, we discuss all these elements and propose an algorithm for POCUS-assisted evaluation of hemodynamic AKI in cirrhosis. Do read it and share your thoughts in the comments section.

Just a reminder for outcome enthusiasts: A diagnostic tool (POCUS) won’t improve mortality unless coupled with the right treatment, which by itself has the ability to do that. That’s not a reason not to make accurate diagnosis. Does putting stethoscope on someone’s chest improve mortality?


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