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Sickle Cell Disease and Pulmonary Disease in HIV - 8/9/2012

posted Aug 9, 2012, 3:27 PM by Rohit Das   [ updated Dec 27, 2012, 7:15 AM by Purnema Madahar ]

Today, we had our first morning report of the year. Scott Schafler presented a very interesting and complicated case of sickle cell disease with vaso-occlusive crisis (VOC), complicated by acute chest syndrome (ACS) and a hyper-hemolytic reaction. Brief review:         

  • ACS is the most common pulmonary complication of sickle cell disease, and often occurs after VOC. It is the second most common reason for hospitalization, and the leading cause of death in sickle cell patients.        
  •  It is diagnosed in the presence of a new lung infiltrate, along with consistent symptoms and signs – fever, chest pain, respiratory symptoms, and/or hypoxemia.        
  •  There are varying degrees of severity, and consequently varying ways to manage ACS. Treatment can be conservative, and in severe cases, much more aggressive with steroids and exchange transfusion.
Sickle cell disease is something I feel like we become a bit desensitized to here in the Bronx, given its high prevalence. However, it’s important to realize that it is a very complex disease, has multi-organ long-term ramifications, and has a major impact on the morbidity and mortality of our population.

As mentioned, this patient also had a presumed “hyper-hemolytic” reaction around the same time of her acute chest episode. The pathophysiology of this complex phenomenon is not well understood, and even the actual existence of this syndrome is debated. Nevertheless, it seems to be a complication of RBC transfusion, and is associated with ACS and VOC episodes.         

  • There are acute (<7 days post-transfusion) and delayed forms. In the acute form, there is usually no serological evidence of alloantibodies.         
  • The syndrome is marked by an abrupt decrease in Hg, increase in markers of hemolysis, and actually a DECREASE in reticulocyte count. The latter is thought to be due to transfusion-induced suppression of erythropoiesis vs. peripheral consumption by macrophages – complicated.      
  •   IVIG and systemic steroids are recommended, though this is largely based on case reports. It is somewhat suggestive that macrophages may indeed be the predominant culprit.

Mary Gover, Scott’s supervisory protégé, also presented a case at resident report of a male in his 50s with late-stage HIV/AIDS presenting with 2-3 weeks of dyspnea. He becomes very hypoxic with exertion, and has impressive diffuse interstitial infiltrates on chest imaging. A brief review:

  • The differential for pulmonary illnesses in HIV/AIDS is relatively broad, but always remember that the most common disease remains the most frequent – bacterial PNA.
  • Bacterial PNA occurs more frequently in HIV patients as compared to those without HIV. S. pneumoniae is the most common pathogen. Much like other HIV-related illnesses, the incidence of bacterial PNA has decreased with the advent of HAART.
  • PCP is typified by a gradual presentation of shortness of breath. Exam can be normal in up to 50% of cases, and even initial chest imaging can be normal in up to 25% of cases.
  • Treatment of choice is Bactrim, with steroids if necessary (room air PaO2 < 70 or A-a gradient > 35). Bactrim PPx is very effective, with an estimated risk of 1-2% over a 36 month period in one study.

Taking a more broad perspective, Dr. Ostrowsky brought up some interesting points about the changing spectrum of pulmonary illness with the advent of HAART:      

  • With HIV patients living longer and surviving opportunistic infections, diseases like COPD are becoming more commonplace, which is not that surprising. Interestingly though, some studies have suggested that HIV alone is a risk factor for COPD, implying a causal association with as of yet unclear pathophysiologic mechanisms.
  • HIV seems to also be independently associated with lung cancer (hazard ratio of 3.6 in one study), thought to be related to the potential oncogenic effects of HIV.

So, some food for thought…

  • Review and list the renal, pulmonary (besides ACS), infectious, cerebrovascular and gastrointestinal complications of sickle cell disease.
  • Hydroxyurea is a very useful therapy in SS patients. What is its mechanism? By how much percent does hydroxyurea decrease VOC rates, on average, per year?
  • Important factoids about the natural history of HIV…What is the mean CD4 at seroconversion? What is the mean CD4 one year after seroconversion? Subsequently, how rapidly does the CD4 count decline, on average, per year?

If there are any interns and/or residents out there attempting to satisfy their hunger for me answers!!! An especially consistent, inquisitive mind might just end up being rewarded…

Until next week…Have a good weekend!

Courtesy of Dr. Shapiro
Yale et. al., Am Family Physician 2000, 61(5): 1349-1356

Courtesy of Mary Gover
Win, Expert Rev. Hematol 2009, 2(2): 111-115

Hull et. al., Chest 2008, 134(6): 1287-1298