ID - HIV

Question 1

What is HIV?

Answer 1

Retrovirus affecting CD4+ helper T-lymphocytes.Causes reduced immune surveillance and immune response to infection. This leads to increased risk of malignancy and opportunistic infection.It can be transmitted horizontally or vertically.

Question 2

How is HIV classified?

Answer 2

Centres for Disease Control and Prevention classification:
Group 1: Acute seroconversion illness: High viral load, non-specific symptoms, 3 month period during which IgG not detectable.
Group 2: Asymptomatic infection
Group 3: Persistent generalised lymphadenopathy
Group 4: Symptomatic HIV infection: low CD4 count (<200 cells/mm3), opportunistic infection or AIDS defining illness.

Question 3

How do patients with HIV present to critical care?

Answer 3

1. Respiratory failure - Most common cause - PCP (25-50% of respiratory HIV admissions) - TB2. CVS - IHD (atherosclerosis may be exacerbated by HAART) - endocarditis/myocarditis3. Liver failure - co-infection with Hep B or C - hepatotoxicity from NRTI/NNRTI4. GI - CMV colitis5. Renal - HIV-associated nephropathy (HIVAN)6. Neurological - Opportunisitic infections inc fungal, TB - lymphoma, aspregilloma, toxoplasmosis, abscesses - Progressive multifocal leukoencephalopathy.

Question 4

What is the prognosis HIV patients admitted to ICU?

Answer 4

Depends upon the stage of their disease and their state of immunocompromise/CD4 count.HIV positive patients on treatment have a normal life expectancy.Those with AIDS defining disease or infection have a poorer prognosis.

Question 5

What is PCP? How is it treated?

Answer 5

Fungal infection caused by Pneumocystis jirovecii. Presents with breathlessness and dry cough.Examination is unremarkable, ABG shows hypoxia, CXR shows bilateral hilar/widespread opacifications.Antimicrobial treatment includes: Co-trimoxazole, pentamidine, primaquine, dapsone.Steroids given early reduces need for invasive ventilation and death (in those with HIV).

Question 6

How is HIV treated?

Answer 6

Prevention
Active therapies include HAART (highly active anti-retroviral therapy):
- NRTI (nucleoside reverse transcriptase inhibitors) - lactic acidosis, hepatic steatosis.
- NNRTI (non-nucleoside reverse transcriptase inhibitors) - Hepatotoxicity
- Protease inhibitors - SJS, Dyslipidaemias
- Fusion inhibitors - GI side effects

Question 7

What are the challenges of HIV treatment on the ICU?

Answer 7

Same as in other patients with the addition of immunocompromise and HAART.
Immunocompromise:
- need to cover opportunistic infections
- HAART:
- Drug delivery - most can only be given enterally
- Impaired absorption
- PPIs, low gut motility, interruptions to feed.
- Dosing - Hepatic insufficiency reduces available dosing
- Drug interactions
- Toxicity complications
- should only be initiated if:
1. AIDS defining illness
2. CD4 <200
3. Anticipated long ICU stay
4. Deterioration despite optimal ITU therapy.

Question 8

What is immune reconstitution syndrome? How is it managed?

Answer 8

IRIS can occur following the initiation of HAART and recovery of the immune response results in widespread inflammatory syndrome.Treatment involves appropriate management for the opportunistic infection, steroids and supportive management.