Recently, we were asked to see a patient on the consult service with a rising creatinine, a BUN of close to 200 and decreased urine output. The patient was a diabetic who had an STEMI several months previously complicated by pneumonia and cardiogenic shock. He was cachectic, did not have any edema or ascites and because of his trach-collar, I put “unable to assess JVD” in my note. His BUN had been high (above 100) for more than 4 weeks (not on TPN, steroids, no GI bleeding) as he was aggressively diuresed for heart failure and his creatinine had been rising slowly which, given his low muscle mass, indicated a significant reduction in GFR. My attending also assessed the patient and felt that his JVP was elevated and recommended diuresis. The primary team, in contrast, felt that his JVP was low and they recommended fluids. The assessment of the JVD is a notoriously difficult exam and very hard to master if one does not do it appropriately as described in a previous post. The patient received 2 liters of fluid and his cardiac status worsened so he was started on dialysis several days later for worsening renal function and volume removal.
This case illustrates the difficulty in accurately assessing volume status in patients in general.
When was the last time you assessed a JVD comfortably? We often say "this patient is dry" or that he needs diuresis but how accurate are our assessments based on the clinical exam alone?
A previous post discussed the JVP and its use as a tool for volume status assessment and cited a systematic review stating that there is a “poor relationship between the isolated inspection of CVP and prediction of blood volume and fluid responsiveness.” One of my attendings gave me an article on this topic several weeks ago: "Clinical assessment of extracellular fluid volume in hyponatremia". The article assessed the clinical judgment of volume status by one of the authors (including cardiac parameters, JVP, orthostatic changes, skin turgor, moisture in the axillae, hydration of mucous membranes) and volume status was 'objectively' assessed by spot urine samples of sodium and creatinine and BUN, norepinephrine and plasma renin concentrations. The clinical assessment was only able to identify 47 % of hypovolemic patients and 48% of normovolemic patients whereas the spot urine sodium clearly separated hypovolemic from normovolemic patients.
The "Bible" of physical examination - Evidence Based Physical Diagnosis by Steven McGee - attributes a low sensitivity or specificity or both to the most common findings used when assessing hypovolemia (the highest likelihood ratio was 2.8 for a dry axilla; in contrast, dry mucous membranes, tongue furrows, sunken eyes, confusion, weakness or unclear speech did not have a significant likelihood ratio). Capillary refill time has been compared only once to a diagnostic standard and was found to have no diagnostic significance.
An intriguing series in JAMA about the rational physical exam stated in the conclusion that "in patients with vomiting, diarrhea, or decreased oral intake, few findings have proven utility, and clinicians should measure serum electrolytes, serum blood urea nitrogen, and creatinine levels when diagnostic certainty is required."
The bottom-line I learned from all of this is: our examination at the bedside is notoriously unreliable in making accurate statements about a patient's volume status and objective parameters need to be taken into account to get a complete picture. A previous post discussed the use of urine electrolytes as a more objective tool for assessing volume status in addition to clinical examination.
Posted by Florian Toegel