Month: November 2016

Take the P4P Quiz (#1)!

FA Manian MD, MPHLeave a comment

With over 100 pearls posted, I thought it would be fun to take a quiz on topics covered to date!

Multiple choice questions

  1. Your patient with hypertensive crisis is admitted with yellow discoloration of skin but not sclera. Which of the following might explain your finding?
    1. Hypothyroidism
    2. Excessive ingestion of squash or carrots
    3. Liver disease
    4. Nephrotic syndrome
    5. All of the above
  2. Your patient with COPD is admitted with acute exacerbation of his disease without a clear trigger or explanation.  Based on published literature, his risk of concurrent pulmonary embolism is approximately…
    1. 0-10%
    2. 15-20%
    3. 30-40%
    4. 50%
    5. > 60%
  3. Your diabetic patient has developed hypoglycemia while being treated with trimethoprim-sulfamethoxazole for a urinary tract infection. A potential explanation for this finding include:
    1. Trimethoprim serving as an insulin secretagogue
    2. Sulfamethoxazole serving as an insulin secretagogue
    3. Reduction of insulin renal clearance by sulfamethoxazole
    4. Increased renal excretion of glucose due to sulfamethoxaole
    5. All of the above
  4. Your patient with urosepsis and E.coli bacteremia presents with new-onset direct hyperbilirubinemia (4.0 mg/dl). His ultrasound of the liver and biliary tree is normal. The most likely explanation for his hyperbilirubinemia  is…
    1. Hemolysis due to sepsis
    2. Gilbert’s syndrome
    3. Common bile duct obstruction due to stone
    4. Cholestasis due to sepsis-induced cytokines
    5. None of the above
  5. Your 55 y old patient is admitted for alcohol withdrawal. You note “Frank’s sign” on his exam. All of the following is true of this sign except…
    1. It was first discovered by a surgeon
    2. It describes a diagonal earlobe crease
    3. It may be a potential marker of coronary artery disease, especially in those 60 y of age or younger
    4. It is associated with alcoholic cirrhosis
    5. It’s pathogenesis may be related to the breakdown of type I collagen due to oxidative stress in atherosclerosis

 

True or false questions

1. Patients with reported shellfish allergy have a significantly higher rate of allergic reactions to iodinated contrast media than those without shellfish allergy.     T              F

2. The new AABB guidelines recommend using a hemoglobin threshold of 7.0 g/DL for all hospitalized patients in the absence of active hemorrhage.    T             F

3. Vitamin D deficiency may present as proximal muscle weakness before any biochemical signs such as hypocalcemia develop.  T         F

4. “SPICE” organisms include multi-drug resistant Staphylococcus aureus and  Pseudomonas aeruginosa.   T            F

5. Prophylactic subcutaneous heparin can be associated with hyperkalemia.

T             F

 

For answers: Scroll down past the bonus picture quiz below….

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Take the P4P Quiz (#1)!

What are the potential pitfalls in reliance on serum creatinine levels or urine output in sepsis-associated acute kidney injury (SA-AKI)?

FA Manian MD, MPH, , , Leave a comment

Although serum creatinine and urine output are usually easily measured, several limitations in their interpretation in patients suspected of having sepsis and AKI are worth emphasizing1.

First, there is an inherent lag of hours between a drop in glomerular filtration rate (GFR) and a rise in serum creatinine concentration. Second, in critically ill hypotensive patients with sepsis receiving aggressive fluid resuscitation, hemodilution may mask serum creatinine rise and delay the diagnosis of AKI by a day. Third, sepsis itself may reduce muscular production of creatinine, even in the absence of weight loss, as demonstrated in animal studies2.  Fourth, patients receiving diuretics may fail to meet criteria for AKI diagnosis based on reduced urine output alone because of increased urine output.  

Lastly, as renal function deteriorates, the half-life of serum creatinine increases from several hours to several days3, prolonging the time needed to achieve a new steady-state that may be more reflective of the concurrent GFR.

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 References

  1. Godlin M, Murray P, Mehta. Clinical approach to the patient with AKI and sepsis. Semin Nephrol 2015;35:12-22.
  2. Doi K, Yuen PST, Eisner C, et al. Reduced production of creatinine limits its use as marker of kidney injury in sepsis. J Am Soc Nephrol 2009;20:1217-21.
  3. Chiou WL, Hsu FH. Pharmacokinetics of creatinine in man and its implications in the monitoring of renal function and in dosage regimen modifications in patients with renal insufficiency. J Clin Pharmacol. 1975; 15(5-6):427-34.
What are the potential pitfalls in reliance on serum creatinine levels or urine output in sepsis-associated acute kidney injury (SA-AKI)?

Should I routinely consider the possibility of pulmonary embolism (PE) in my patients hospitalized for syncope?

FA Manian MD, MPH, , , , , , Leave a comment

Syncope is a well-known initial manifestation of pulmonary embolism (PE)1.  However, given the varied causes of syncope, determining the prevalence of PE among patients hospitalized for syncope is important.   

A multicenter prospective study2 enrolled 560 patients not already on anticoagulation who were hospitalized for a first episode syncope.  Of patients who had either a high pretest probability for PE, positive D-dimer assay or both, PE was diagnosed in 17%, or nearly 1 of 6 of enrolled patients, based on CT or ventilation/perfusion scan. PE was found more frequently among patients with syncope of undetermined cause than those with an alternative explanation (25.4% vs 12.7%). 

Another multicenter prospective study (2019), however, found a much lower prevalence of PE (0.6%) among patients evaluated in the ED for syncope, including those who were not hospitalized.3 A related commentary on the article reported a prevalence of 4.1% in the total study population, assuming a “worst-case scenario calculation.” 4 

Given these divergent results, perhaps the best advice is to consider PE as cause of syncope in the proper context and minimize overtesting when suspicion remains low.

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References 

  1. Thames MD, Alpert JS, Dalen JE. Syncope in patients with pulmonary embolism. JAMA 1977;238:2509-2511. https://www.ncbi.nlm.nih.gov/pubmed/578884
  2. Prandoni P, Lensing AWA, Prins MH, et al. Prevalence of pulmonary embolism among patients hospitalized for syncope. N Engl J Med 2016;375:1524-31. http://www.nejm.org/doi/full/10.1056/NEJMoa1602172
  3. Thiruganasambandamoorthy V, Sivilotti MLA, Rowe BH, et al. Prevalence of pulmonary embolism among emergency department patients with syncope: a multicenter prospective cohort study [published online January 25, 2019]. Ann Emerg Med. doi:10.106/j.annemergmed.2018. https://www.annemergmed.com/article/S0196-0644(18)31535-X/fulltext
  4. Anonymous. Pulmonary embolism uncommon in syncope hospitalizations. Pulmonology Advisor. February 6, 2019.  https://www.pulmonologyadvisor.com/pulmonary-embolism-uncommon-in-syncope-hospitalizations/printarticle/832069/

 

Contributed in part by Rebecca Berger  MD, Department of Medicine, Mass General Hospital, Boston, MA

 

Should I routinely consider the possibility of pulmonary embolism (PE) in my patients hospitalized for syncope?

How is the pathophysiology of sepsis-associated acute kidney injury (SA-AKI) different than AKI due to non-septic conditions?

FA Manian MD, MPH, , , , Leave a comment

Sepsis accounts for up to one-half of AKI cases in developed countries1.  Although sepsis-mediated hypoperfusion causing tubular necrosis has traditionally been implicated as the primary basis for SA-AKI,  an increasing number of studies have suggested that SA-AKI is a distinct subset of AKI differentiated from other causes by unique hemodynamic and inflammatory/immune-related mechanisms.  

Many animal and limited human studies have found that renal blood flow is an inconsistent predictor of SA-AKI, possibly related to the redistribution of blood in the renal microvasculature to the detriment of the renal medulla in sepsis2.

Cytokine-mediated response in sepsis can also lead to tubular cellular injury without necessarily causing necrosis. Of interest, an autopsy study found histological features of acute tubular necrosis in only 22% of patients with clinical diagnosis of SA-AKI 3.  

Differences in its pathophysiology may at least in part explain why oliguria, renal function recovery, hemodialysis and death are more common among SA-AKI patients4.

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References

  1. Alobaidi R, Basu RK, Goldstein SL, Bagshaw SM. Sepsis-associated acute kidney failure. Semin Nephrol 2015;35:2-11.  https://www.ncbi.nlm.nih.gov/pubmed/25795495
  2. Maiden MJ, Otto S, Brealey JK, et al. Structure and function of the kidney in septic shock. Am J Resp Crit Care Med 2016;194:692-700. https://www.atsjournals.org/doi/abs/10.1164/rccm.201511-2285OC
  3. Langenberg C, Bagshaw SM, May CN, Bellomo R. The histopathology of septic acute kidney injury: a systemic review. Crit Care 2008;12:R38.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2447560/
  4. Cruz MG, de Oliveira Dantas JGA, Levi TM, et al. Septic versus non-septic acute kidney injury in critically ill patients: characteristics and clinical outcome. Rev Bras Ter Intensiva 2014;26:384-391. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4304467/
How is the pathophysiology of sepsis-associated acute kidney injury (SA-AKI) different than AKI due to non-septic conditions?

My patient just had a run of ventricular tachycardia (VT) at a rate of 120 beats/min lasting 18 seconds without any symptoms. Does this arrhythmia meet the criteria for nonsustained VT (NSVT) and what is its significance?

FA Manian MD, MPH, , , Leave a comment

Although NSVT is often defined as 3 (sometimes 5) or more consecutive beats arising below the atrioventricular node with a heart rate >100 beats/min lasting <30 s, this definition is not universal. Other definitions of NSVT include >120 beats/min using a duration cutoff of 15 s,  or at times no strictly defined diagnostic criteria1.  

NSVT can be observed in a variety of individuals, ranging from apparently healthy people to those with significant heart disease.  Whether NSVT provokes sustained life-threatening arrhythmias or is merely a surrogate marker of a more severe underlying cardiac pathology is unclear in most clinical settings 1. 

Because our patient  meets the generally observed criteria for NSVT, we should exclude an underlying occult pathology responsible for the arrhythmia and, in the case of known cardiac disease,  risk-stratify the patient for appropriate management2.  

The prognostic significance of NSVT is heavily influenced by the type and severity of underlying heart disease.  Patients with NSVT in the setting of >24 h post-acute myocardial infarction and those with chronic ischemic heart disease with left ventricular ejection fraction <40%  have a less desirable prognosis2. The management of patients with NSVT is generally aimed at treating the underlying heart disease.

References

  1. Katritsis DG, Zareba W, Camm AJ. Nonsustained ventricular tachycardia. J Am Coll Cardiol 2012;60:1993-2004. http://www.onlinejacc.org/content/60/20/1993
  2. Katritisis DG, Camm AJ. Nonsustained ventricular tachycardia: where do we stand? Eur Heart J 2004;25:1093-1099. https://academic.oup.com/eurheartj/article/25/13/1093/465312
My patient just had a run of ventricular tachycardia (VT) at a rate of 120 beats/min lasting 18 seconds without any symptoms. Does this arrhythmia meet the criteria for nonsustained VT (NSVT) and what is its significance?

What is the significance of a prolonged activated partial thromboplastin time (aPTT) in my patient with suspected antiphospholipid syndrome (APS)?

FA Manian MD, MPH, , , , Leave a comment

APS is an acquired hypercoagulable state which presents classically as recurrent arterial and/or venous thrombosis and is a major cause of late first- and second-trimester spontaneous fetal loss. In addition to thrombotic complications, diagnosis of APS requires the presence of ≥ 1 of the following antiphospholipid antibodies on 2 occasions ≥12 weeks apart: 1) anti-ß2-glycoprotein 1 antibodies; 2) anticardiolipin antibodies; and 3) lupus anticoagulant (LA)1.  

An unexpected prolongation of aPTT may be a clue to the presence of APS and may be explained by the in vitro prevention of the assembly of the prothrombinase complex—which catalyzes the conversion of prothrombin to thrombin— by LA2,3.  

Because the phospholipid component of the reagent used in aPTT tests determines its sensitivity to LA, aPTT results may vary, influenced by the type and concentration of phospholipids used in the assay. Other factors such as acute phase reaction associated with increased fibrinogen and factor VIII levels may also impact the results by shortening the aPTT and potentially masking a weak LA2.

 

 

References 

  1. Giannakopoulos B, Passam F, Ioannou Y, Krilis SA. How we diagnose the antiphospholipid syndrome.Blood. 2009;113:985-94.
  2. 2. Abo SM, DeBari VA. Laboratory evaluation of the antiphospholipid syndrome. Ann Clin Lab Sci 2007;37:3-14.
  3. Smock KJ, Rodgers GM. Laboratory identification of lupus anticoagulants. Am J Hematol. 2009;84(7):440-2.

 

 

Contributed by Ricardo Ortiz, medical student, Harvard Medical School

What is the significance of a prolonged activated partial thromboplastin time (aPTT) in my patient with suspected antiphospholipid syndrome (APS)?

Should I use a hemoglobin level of 7 or 8 g/dL as a threshold for blood transfusion in my hospitalized patient?

FA Manian MD, MPH, , , , , , , , , , , 1 Comment

Unlike its previous 2012 guidelines that recommended overlapping hemoglobin level triggers of 7 g/dL to 8 g/dL for most inpatients, the 2016 guidelines from AABB (formerly known as the American Association of Blood Banks) assigns 2 distinct tiers of hemoglobin transfusion triggers: 7 g/DL for hemodynamically stable adults, including those in intensive care units, and 8 g/dL for patients undergoing cardiac or orthopedic surgery or with preexisting cardiovascular disease1 , often defined as history of coronary artery disease, angina, myocardial infarction, stroke, congestive heart failure, or peripheral vascular disease2,3.  

These recommendations are based on an analysis of over 30 randomized trials, taking into account the potential risks of withholding transfusions, including 30-day mortality, and myocardial infarction. The new 2-tier recommendation specifically excludes those with acute coronary syndrome, severe thrombocytopenia (patients treated for hematological or oncological reasons who are at risk of bleeding), and chronic transfusion-dependent anemia.

The guidelines also emphasize that good clinical practice dictates considering not only the hemoglobin level but the overall clinical context when considering blood transfusion in patients. These factors include alternative therapies to transfusion, rate of decline in hemoglobin level, intravascular volume status, dyspnea, exercise tolerance, light-headedness, chest pain considered of cardiac origin, hypotension, tachycardia unresponsive to fluid challenge, and patient preferences.

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References

  1. Carson JL, Guyatt G, Heddle NW. Clinical practice guidelines from the AABB red blood cell transfusion thresholds and storage. JAMA. Doi:10.1001/jama.2016.9185. Published online October 12, 2016. https://www.ncbi.nlm.nih.gov/pubmed/27732721
  2. Carson JL, Duff A, Poses RM, et al. Effect of anemia and cardiovascular disease on surgical mortality and morbidity. Lancet 1996;348:1055-60. https://www.ncbi.nlm.nih.gov/pubmed/8874456
  3. Carson JL, Siever F, Cook DR, et al. Liberal versus restrictive blood transfusion strategy: 3-year survial and cause of death results from the FOCUS randomized controlled trial. Lancet 2015;385:1183-1189. https://www.ncbi.nlm.nih.gov/pubmed/25499165
Should I use a hemoglobin level of 7 or 8 g/dL as a threshold for blood transfusion in my hospitalized patient?