Point of care ultrasonography (POCUS) is rapidly evolving as a valuable adjunct to physical examination among internists and subspecialists. It reduces fragmentation of care and quickly provides answers to simple clinical questions at the bedside, thereby enhancing patient care and satisfaction. In addition, using bedside ultrasound as the first line investigation may eliminate unnecessary radiation and contrast exposure. The advent of highly portable and affordable ultrasound devices has made the use of POCUS more practical and user-friendly [Figure 1]. One can choose the machine depending on the budget and sonographic applications performed. It is no wonder POCUS has been described as the fifth pillar to bedside physical examination along with inspection, palpation, percussion and auscultation .
Figure 1. The different ultrasound options now available on the front line.
While nephrologists could benefit immensely from POCUS , its use remains sporadic and limited to very few institutions, the major hurdle being lack of appropriate specialty-oriented training. Also, the skepticism involved in adopting a new ‘practice-changing’ technology makes the value of POCUS underappreciated. Moreover, the scope of practice has not been defined and there is no universally adopted training curriculum. In fact, we have recently proposed a model curriculum based on our experience at the University of Florida that serves as an initial framework for budding programs .
Some of the common clinical scenarios [Figure 2] and POCUS applications relevant to nephrology practice are outlined below.
Figure 2. Common scenarios in POCUS.
Patients with acute kidney injury
Acute kidney injury (AKI), previously known as acute renal failure is the commonest reason to seek nephrology consultation, and in almost all such cases, a renal sonogram is obtained to exclude urinary tract obstruction. Nephrologist-performed POCUS provides the answer to this simple question right away, which alleviates the need to wait for the formal ultrasound report to guide management. [Figure 3]. Moreover, it also gives an idea of the chronicity of the underlying kidney disease based on the kidney length and parenchymal thickness, as well as may reveal other relevant structural abnormalities. Above all, kidney ultrasonography is relatively an easy skill to learn with limited pathologies, making it a great POCUS application. Similarly, simultaneous bladder sonography may provide clues to simple, yet easily correctible issues such as Foley catheter obstruction or other pertinent pathologies.
Figure 3. Ultrasound pathways with and without POCUS.
Chronic kidney disease patients in the clinic
Similar to the above scenario, renal sonogram is frequently obtained as a part of chronic kidney disease (CKD) evaluation to exclude any structural abnormalities. Nephrologist-performed POCUS saves a trip to radiology department for the patient unless a formal scan is deemed necessary. Similarly, ultrasound surveillance of the newly placed arteriovenous access in patients with advanced CKD in nephrology office may evade the need for routine visits to vascular surgeon. Also, as CKD patients are prone to developing hypervolemia, objectively assessing extravascular lung water by POCUS helps to titrate the diuretic dose more effectively instead of relying solely on the symptoms or patient-reported weight. In my personal experience, discussing POCUS findings with the patients enhances conversations in any clinical setting [Figure 4] and strengthens physician-patient relationship. This is particularly important for nephrologists, as they take care of the patients with long-term follow up needs.
Figure 4. Discussing POCUS findings in diffrent clinical settings strengthens the physician-patient relationship.
Patients with shortness of breath
It is not uncommon to encounter a patient who is short of breath in nephrology practice, whether in the dialysis unit or inpatient ward. While the most likely etiology is hypervolemia, we need to be aware of other potential causes. For example, a patient with glomerulonephritis on immunosuppressive therapy may present with pneumonia, a nephrotic syndrome patient may develop acute pulmonary embolism and some patients are predisposed to developing pleural or pericardial effusions. POCUS is a great tool to distinguish between pulmonary and cardiac causes and narrow the differential diagnosis in this scenario. Performing a quick multi-system POCUS [Figure 5] to look for lung A- and B-lines, effusions, inferior vena cava collapsibility, cardiac pump function and excluding deep venous thrombosis can provide valuable information and guide management. Furthermore, POCUS helps to monitor response to treatment (e.g. diuretics or dialysis) in patients with hypervolemia, avoiding the need for multiple chest X-rays [Figure 6].
Figure 5. A quick, multi-system tool POCUS too can be useful in a variety of settings.
Figure 6. POCUS can help to monitor response to treatment and help to avoid the need for multiple chest X-rays.
End-stage renal disease (ESRD) patients on dialysis are at higher risk of cardiovascular mortality and chronic hypervolemia is a major contributor . In this patient population, physical examination is not reliable and lung POCUS is an invaluable tool to assess volume status and guide the amount of ultrafiltration. Interestingly, a study of 79 ESRD patients on hemodialysis has shown that lung crackles, either alone or combined with peripheral edema, very poorly reflect interstitial lung edema (combined sensitivity ~13%) detected by POCUS  [Figure 7]. ‘Asymptomatic’ pulmonary congestion detected by POCUS should not be taken lightly as it has been shown to predict cardiac events and mortality in ESRD patients .
Nephrologists need to be watchful of pericardial effusion in these patients, especially in the context of unexplained intradialytic hypotension and use of medications such as Minoxidil or hydralazine. Ability to perform POCUS remarkably increases the sensitivity of physical examination in these scenarios. POCUS also plays a role in the evaluation of dialysis access dysfunction as well as complications such as stenosis, pseudo aneurysms, thrombosis and steal syndromes.
Figure 7. B-lines on lung ultrasound vs physical examination
Sonographic guidance is now standard of care for most percutaneous procedures performed by the nephrologists such as dialysis catheter insertion and kidney biopsy. For kidney biopsy however, the patient is usually taken to the radiology department for assistance with the ultrasound, even if the nephrologist performs biopsy. If nephrologists are able to perform ultrasound-guided biopsy [Figure 8] by the bedside, it expedites patient care, particularly in the management of renal transplant recipients. POCUS also aids in the cannulation of marginal or deep arteriovenous accesses in dialysis patients, which can minimize infiltrations. It is also a great way to train patients for self-cannulation (those undergoing home hemodialysis) .
Figure 8. Beside ultrasound-guided biopsy can expedite patient care
Although short-term training opportunities exist for practicing nephrologists, fellowship-based longitudinal POCUS training is desirable for long-term skill retention. Regardless of the training pathway, the competency and confidence will decay without practice, similar to any other skill in Medicine. Until we come up with guidelines for curriculum development, competency assessment and scope of practice, a multidisciplinary approach in collaboration with other specialties such as emergency and critical care medicine can prove beneficial. On the other hand, with ongoing incorporation of POCUS into medical school and residency training curricula, it is quite likely that future nephrology trainees are fully competent prior to their fellowship.
In addition to scores of online resources mainly geared towards emergency medicine and critical care physicians , the University of Florida video curriculum has been specifically designed to cover all the diagnostic POCUS applications pertinent to nephrology . Additionally, Nephropocus.com is a website I have created to share POCUS scenarios and literature pertinent to nephrology practice. As mentioned, the most crucial thing to achieve mastery is continued scanning and integration of POCUS findings into day-to-day clinical decision making.
By Dr Abhilash Koratala, MD
You can follow him on Twitter, YouTube or via his educational website nephropocus.com
- Narula J, Chandrashekhar Y, Braunwald E. Time to Add a Fifth Pillar to Bedside Physical Examination: Inspection, Palpation, Percussion, Auscultation, and Insonation. JAMA Cardiol. 2018;3(4):346-350.
- Koratala A. Focus on POCUS: it is time for the kidney doctors to upgrade their physical examination. Clin Exp Nephrol. 2019;23(7):982-984.
- Koratala A, Segal MS, Kazory A. Integrating Point-of-Care Ultrasonography into Nephrology Fellowship Training: A Model Curriculum. Am J Kidney Dis. 2019 Jul;74(1):1-5
- Agarwal R. Volume overload in dialysis: the elephant in the room, no one can see. Am J Nephrol. 2013;38(1):75-7.
- Torino C, Gargani L, Sicari R, Letachowicz K, et al. The Agreement between Auscultation and Lung Ultrasound in Hemodialysis Patients: The LUST Study. Clin J Am Soc Nephrol. 2016;11(11):2005-2011.
- Zoccali C, Torino C, Tripepi R, Tripepi G, et al. Pulmonary congestion predicts cardiac events and mortality in ESRD. J Am Soc Nephrol. 2013;24(4):639-46.
- Niyyar VD, O’Neill WC. Point-of-care ultrasound in the practice of nephrology. Kidney Int. 2018;93(5):1052-1059.
- POCUS resources https://spocus.org/FOAMED Last accessed: 10/5/2019
- UF Nephrology POCUS video curriculum https://www.youtube.com/watch?v=oBG134G7dK0&list=PLFdeth7h_O6aGClfMys1ITA3mikmPKZcn Last accessed: 10/5/2019