Setting: ED
CC: “I keep coughing and I can’t breathe.”
VS: BP: 108/72 mm Hg; P: 88 beats/minute; T: 101.4°F; R: 26 breaths/minute
HPI: A 54-year-old man with acquired immunodeficiency syndrome (AIDS) arrives at the ED with several days of increasing dyspnea and cough. The dyspnea is definitely worse on exertion and that is the main reason he has come to the ED. The cough is dry and nonproductive: “Nothing comes up when I cough.” He has not measured his temperature.
PMHX:
AIDS: does not know his CD4 count
Oral thrush
Medications: none for past 6 months; “I’m supposed to be taking something, but I don’t know the name of it.”
ROS:
Inspiratory “catch”—sharp pain under sternum when he breaths in
PE:
General: thin, wasted appearance
Chest: clear bilaterally
Abdomen: normal
Cardiovascular: normal
Initial Orders:
Oximeter, oxygen, ABG, chest x-ray
CBC
CD4 count
LDH
Pneumococcus is the most common CAP in patients with AIDS.
Reports:
Oximeter: 94% room air saturation
Although the most common CAP in AIDS is pneumococcus, the patient has a dry cough and normal lung examination.
Interstitial pneumonia is associated with a nonproductive cough.
Reports:
ABG: pH 7.49; PCO2 32 mm Hg; PO2 70 mm Hg (on room air)
Chest x-ray: bilateral interstitial infiltrates
CBC: WBCs 3200/μL (low); Hct: 34%; MCV 88 fL
LDH: 825 units/L (elevated)
Interstitial Infiltrates
• Pneumocystis
• Mycoplasma
• Chlamydia pneumonia
• Viral
• Coxiella
“Empty” Alveoli = Dry Cough
What is this patient’s alveolar-arterial (A-a) gradient?
a. 20 mm Hg
b. 24 mm Hg
c. 30 mm Hg
d. 40 mm Hg
e. 45 mm Hg
Answer d. 40 mm Hg
A-a gradient = 150 – (PCO2/0.8 + PO2)
150 – (32/0.8 + 70)
150 – (40 + 70)
150 – 110 = 40 mm Hg
Any cell breakdown causes high levels of LDH.
Why does mycoplasma not appear on Gram stain?
a. No cell wall
b. Intracellular
c. Too small
d. No stainable DNA
Answer a. No cell wall
Mycoplasma does not have a true cell wall. Mycoplasma is encased in a cell membrane that does not pick up Gram stain. Chlamydia and viruses are intracellular. Gram stain does not stain DNA, it stains the cell wall.
Normal LDH strongly excludes Pneumocystis jiroveci pneumonia (PCP).
Once you have the results of the chest x-ray, you can order therapy. Unlike the other forms of pneumonia, PCP is not covered by the usual CAP drugs of ceftriaxone and azithromycin or a quinolone such as levofloxacin, moxifloxacin, or gemifloxacin.
What is the indication for giving steroids in PCP?
a. PO2 <80 mm Hg or A-a gradient >25 mm Hg
b. PO2 <70 mm Hg or A-a gradient >25 mm Hg
c. PO2 <70 mm Hg or A-a gradient >35 mm Hg
d. PO2 <60 mm Hg or A-a gradient >35 mm Hg
Answer c. PO2 <70 mm Hg or A-a gradient >35 mm Hg
Glucocorticoids such as prednisone give a 50% decrease in mortality in a person with severe PCP. Use of steroids are absolutely lifesaving in severe disease. Never be worried about short-term steroid use in acutely ill patients even if they are immunocompromised.
Orders:
Trimethoprim-sulfamethoxazole (TMP-SMZ) IV
Prednisone orally
Pulmonary consultation
Bronchoscopy and bronchoalveolar lavage (BAL)
TMP-SMZ is a folate antagonist.
Advance the clock to get the results of the bronchoscopy. There should be an immediate improvement in respiratory status the same day with the use of steroids. Steroids will decrease fluids or swelling in the interstitial membrane and allow greater transfer of oxygen from the alveolus to the arteriole.
Reports:
BAL: P. jiroveci found
CD4: 18
Pneumocystis jiroveci (Figure 7-4)
• It is a fungus by DNA classification.
• Antifungal drugs do not work.
Figure 7-4. Pneumocystis pneumonia. A silver stain of this material from the lung reveals folded cysts, some of which contain comma-shaped spores. (Reproduced with permission from Connor DH, et al., eds. Pathology of Infectious Diseases, vol. 1. New York: Appleton & Lange; 1997.)
Over the next several days, there is no change to therapy. Decreasing the steroid dosage will happen after 5 days. Do an “Interval History” every day the patient is in the hospital to confirm improvement.Serum chemistry should be done at least every 2 days in a hospitalized patient undergoing active IV treatment.
Pneumocystis jiroveci
• Formerly Pneumocystis carinii
• Does not grow on fungal media
Reports:
Interval History: “Improved shortness of breath”
Chemistry:
Creatinine 1.8 mg/dL (elevated)
Blood urea nitrogen (BUN): normal
Sodium: 130 mEq/L (normal 135–145 mEq/L)
Glucose: 165 mg/dL
TMP decreases the tubular secretion of creatinine.
All pneumonias cause the syndrome of inappropriate secretion of antidiuretic hormone (SIADH).
Steroids increase glucose:
• Decreased uptake by muscle
• Increase gluconeogenesis
• Permissive action on glucagon
What should you do about these laboratory abnormalities?
a. No action is needed.
b. Stop steroids.
c. Stop TMP-SMZ and switch to IV pentamidine.
d. Stop TMP-SMZ and switch to aerosolized pentamidine.
Answer a. No action is needed.
Move the clock forward and repeat the laboratory tests. You do not need to do anything for these laboratory abnormalities at this mild level. Prednisone is lifesaving in severe PCP and a glucose level of 165 mg/dL is clinically irrelevant for a short period of 2 to 3 weeks. A mild bump up in creatinine level has very limited clinical significance. You will be switching to oral TMP-SMZ at 10 to 14 days to complete the full 3 weeks orally if the patient is stable. Also, IV pentamidine is even more nephrotoxic than TMP-SMZ.
Aerosolized pentamidine is completely inadequate at acute therapy. It is a fourth-line choice used rarely, if at all for prophylaxis of PCP.
TMP decreases the tubular secretion of creatinine.
Advance the clock and recheck the laboratory test results. If there is no further deterioration in chemistry levels, just continue the same treatment. Start antiretroviral medications, such as efavirenz, emtricitabine, and tenofovir. When the patient is improved and ready for discharge, long-term prophylaxis with oral TMP-SMZ is used lifelong, or until the patient’s CD4 count is brought up above 200 with antiretroviral treatment (ART). Steroids are tapered down so that they stop at the time the patient is switched from full-dose IV or oral TMP-SMZ to the prophylactic dose.
When the patient’s CD4 level increases:
• Continue lifelong ART.
• Stop prophylactic medications when the CD4 count is above 200 cells/mm3.