anesthetic considerations for the hiv+ patient

Anesthetic Considerations

for the HIV+ Patient

Veronica Y. Amos PhD CRNA

October 2014

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

DrugsPropofol 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 DrugsCalcium 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

RenalIncreased 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 (T-cell 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 TestingHIV 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