Anesthetic Considerations of the HIV

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Prevalence
In 2011, an estimated 1.1 million persons in the
U.S. were living with HIV infection
1 in 6 (15.8%) are unaware they are HIV positive
Incidence
Centers for Disease Control (CDC) estimated
that approximately 50,000 people are newly
infected with HIV
HIV versus AIDS
HIV: Human Immunodeficiency Virus - a
retrovirus that specifically infects several kinds
of cells in the human body, the most important is
the CD4 T-Lymphocyte
HIV versus AIDS
AIDS: Acquired Immunodeficiency Syndrome When an individual’s CD4 T-Lymphocyte cell
count has fallen below 200, and/or the individual
has developed some specific and opportune
infections.
HIV Targets T Cells
T cells act as the host that the HIV virus needs in
order to replicate
CD4 Receptor Site
CD4 is a protein on the surface of the T cell.
HIV’s gp120 antigen is a mirror image of the CD4
protein.
HIV
Takes Control
of T Cells
Viral RNA needs to become
DNA in order to start the
replication process. Reverse
transcriptase allows the RNA
to borrow material from the
cell and to "write backwards"
a chain of viral DNA.
CD4 Values
Normal: 600 -1200 cells per cubic mm of blood
Meds not needed: 600-350
Increased risk: 350-200 (meds may be started)
Risk for opportunistic infections: less than 200
Viral Load
This test detects and/or measures the amount
(viral load) of RNA of the HIV in the blood
Viral Load
Untreated and uncontrolled HIV viral loads can
range as high as one million or more copies/mL.
A low viral load is usually between 40 to 200
copies/mL, depending on the type of test used.
Viral Load
A viral load result that reads “undetectable”
does not mean that one is cured.
Adverse Drug Effects from
Antiretroviral Drugs (ARVs)
1. Mitochondrial dysfunction
2. Metabolic abnormalities
3. Bone marrow suppression
4. Allergic reactions
Interaction of ARVs with Other Drugs
Propofol and NRTIs may both potentially
promote mitochondrial toxicity and lactic
acidosis and it may be best to avoid propofol
“infusions” in patients receiving ARVs
Pharmacokinetic Interactions
Primarily due to liver enzyme induction or
inhibition, particularly the CYP450 3A4 enzyme
PIs and NNRTIs are the most commonly
implicated group of ARVs in drug interactions.
Enzyme induction or inhibition can affect the
action of several classes of anesthetic drugs
Opioids
The effects of fentanyl may be enhanced by
ritonavir (protease inhibitor) due to both liver
enzyme inhibition and induction
Enzyme inhibition reduces fentanyl clearance
and enzyme induction increases metabolism to
active metabolites such as normeperidine
Benzodiazepines
Saquiniar (PI) can inhibit midazolam’s
metabolism
Combination of PI and NNRTIs – excessive
sedation
Other Drugs
Calcium Channel Blockers may have enhanced
hypotensive effects due to enzyme inhibition
Local anesthetics such as lidocaine may have
increased plasma levels due to enzyme
inhibition
Neuromuscular blocker effects may be
prolonged, even from a single dose of
vecuronium
Other Drugs
Proton Pump Inhibitors, and to a lesser extent
antacids and H2 blockers, may adversely affect
the absorption of the PI atazanavir
PIs impair the metabolism of the cardiac drugs
amiodarone and quinidine
Preferable
Etomidate, atracurium, remifentanil
and desflurane are not dependent
on CYP450 hepatic metabolism, and
therefore, may be preferable drugs
Blood Transfusions
There is evidence that allogenic blood
transfusion in the HIV infected patient can lead
to transfusion-related immunomodulation (TRIM)
and can result in an increase in HIV viral load
Pain
Pain is common in advanced HIV disease and
can be very difficult to treat. The etiology of this
pain can be multi-factorial, including
opportunistic infections such as herpes simples,
peripheral neuropathy and drug-related pain
Organ Involvement
Organ involvement in HIV infection may be a
direct consequence of HIV infection because of
an opportunistic infection or neoplasm, or
related to other causes such as side effects of
the medications
Respiratory
Prevalence of underlying
pulmonary disease is increased
due to the increased risk for
bacterial pneumonia and the
high prevalence of smoking
Respiratory
Both upper and lower airway may be involved
with HIV infection:
- Bronchitis, sinusitis, pneumonia (PCP)
- TB, myobacteria and fungal infections
- Airway obstruction (Kaposi’s sarcoma)
Risks/Recommendations
Risk for postoperative pneumonia is
increased
Carefully evaluate for respiratory
complications in the peri-operative
period: HIV+ patients with active PCP
or a history of PCP are at increased
risk for a spontaneous pneumothorax
Cardiovascular
Increased prevalence of CAD from metabolic
dysfunction due to HIV infection and/or ART
QT prolongation or other cardiac abnormalities
may occur in advanced HIV and/or ART
(methadone, anti-arrhythmics, PI,
antipsychotics)
Cardiovascular
- Dilated cardiomyopathy
- Pericardial effusions
- Endocarditis and valvular lesions
- Acute coronary syndrome
- Vasculitis
- Pulmonary hypertension
Recommendations
Assess for CAD preoperatively
Perform a careful review of
preoperative ECG results
Gastrointestinal
- Difficulty or pain on swallowing
- Increased gastric emptying times
- Bleeding tendency on airway instrumentation/NGT
placement
- Diarrhea with associated electrolyte dysfunction &
dehydration
- Hepatobiliary impairment
- Pancreatitis
Hepatic
Increased prevalence of hepatic
dysfunction from ART or from
preexisting liver disease
Risks/Recommendations
Co-infection with HBV or HCV may predispose to
increased bleeding due to coagulopathy or
thrombocytopenia
Assess preoperatively and dose anesthetics,
antibiotics, and other medications accordingly
Renal
Increased prevalence of renal dysfunction from
HIV-associated nephropathy
-
Acute and chronic disease
- Drug-induced nephrotoxicity, HTN, & diabetes
- HIV-associated nephropathy
Recommendations
Assess for renal dysfunction
preoperatively due to possible
impact on dosing, selection of
anesthetics, and peri-operative
antibiotics
Neurological
- Neurocognitive impairment
- Encephalopathy
- Autonomic neuropathy
- Seizures
Endocrine & Metabolic
- Lipodystrophy (truncal obesity, buffalo hump)
- Raised plasma triglycerides, cholesterol, glucose
- Disorders of the hypothalamic-pituitary-adrenal axis
(Cushings/Addisons)
- Hyponatremia due to syndrome of inappropriate
antidiuretic hormone or adrenal failure
- Hypo/hyperthyroidism
- Lactic acidosis
Hematological
- Anemia
- Neutropenia with severe immunosuppession
- Thrombocytopenia
- Persistent generalized lymphadenopathy
- Hematological malignancies
- Coagulation abnormalities
Recommendations
Consult with hematologist prior
to procedure when platelet
count approaches 50,000
MRSA
Community-acquired is more
common in MSM than in the
general population
Recommendations
Good history of previous MRSA
infections
Use vancomycin instead of
cefazolin for prophylaxis with a
positive history of MRSA
HIV Infected Parturient
The advances in HIV treatment have also
brought down the rate of mother-to-child HIV
transmission significantly. If the mother takes
appropriate medical precautions, including
taking HIV drugs, the rate of transmission can
be reduced from about 25 percent to below 2
percent. In addition, studies have shown that
being pregnant will not make HIV progress
faster in the mother
HIV Infected Parturient
HIV infection does not contraindicate the
administration of neuraxial anesthesia analgesia
during labor and/or for a cesarean section). HIV
is a neurotropic virus, and the CNS is infected
early in the course of the disease.
HIV Infected Parturient
Vertical transmission is increased when CD4 (Tcell counts) decrease below 400 mL and viral
load increases over 1000 copies/mL
Elective C-Sections combined with antiretroviral
therapy has reduced vertical transmission to
<5%
HIV Infected Parturient
Risk factors for vertical transmission include
prolonged preterm rupture of membranes (>4
hrs), chorioamnionitis, presence of STD, lack of
maternal antiviral therapy, and obstetrical
invasive procedures such as cervical cerclage
and amniocentesis
Key Points to Remember
If the HIV patient is on a cocktail and they are
told to hold a HIV med before surgery….they
need to discontinue them all and restart them all
together
Key Points to Remember
Occasionally with surgical intervention there
may be a temporary or transient increase, also
called a blip, in viral load. In people whose viral
load is less than 50 copies, blips are a frequent
occurrence and is not associated with a
sustained increase in viral load.
Risk for Occupational
Transmission of HIV
Percutaneous exposure – approx
0.3%
Mucous membrane exposure –
approx 0.09%
Occupational Exposure
to HIV
Places you at risk:
Percutaneous injury (needlestick or cut with a
sharp object)
Contact of mucous membrane or non-intact skin
Blood, tissue, or other body fluids (cerebrospinal,
synovial, pleural, peritoneal, pericardial, and
amniotic fluid)
Remember
Just because a source patient has an
undetectable serum viral load – it does not
eliminate the possibility of HIV transmission or
the need for post-exposure prophylaxis (PEP ) &
follow-up testing
Recommendations
PEP is recommended
Start PEP medication regimens as soon as
possible (within 72 hrs) after occupational
exposure & continue for a 4-week duration
PEP should contain 3 (or more) ART drugs that
have the fewest side-effects & are best tolerated
Follow-up Testing
HIV testing at baseline, 6 weeks, 12 weeks, 6
months post-exposure
Complete blood count, renal and hepatic
function tests at baseline and 2 weeks
HIV test results should preferable be given to the
exposed healthcare provider at face to face
appointments
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