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.
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. HIV Takes Control of T Cells
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 CD4 Values
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 • Neutropeniawith 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.