Immunity & Infections Flashcards
HIV Systemic Effects
Neurologic
CNS = HIV “reservoir”
- Sensory neuropathy: numbness, tingling, painful dysesthesias and paresthesias
- Encephalopathy or AIDS dementia complex: cognitive, motor, and behavioral changes
- Opportunistic infections/ malignancies
- HAART related cerebral vascular disease
perform good baseline neuro exam, consider inflamm demyelinization sim to MS pts, weigh risks /benefits of regional if pt has severe neuropathy
HIV
Systemic Effects
Respiratory
Respiratory (Infectious)
- PCP
- Bacterial pneumonia
- TB
- Aspergillosis
- CMV
- Oral/pharyngeal candidiasis
- Kaposi’s sarcoma
- Herpes
- direct HIV pulmonary destruction
- leads to respiratory failure, PTX, chronic lung disease (much like emphysema)
- Tracheobronchial/great vessel compression w/ adenopathy, endobronchial Kaposi’s (massive hemoptysis)
consider if they have an active infection. Postpone elective sx until after treatment.
HIV
Systemic Effects
Cardiac
Cardiac (chronic trophic viral infection + co-infection/drug toxicity related)
- Pericarditis
- pericardial effusion
- myocarditis (late stages of infection)
- dilated cardiomyopathy
- endocarditis (IVDA)
- pulmonary HTN
- thromboembolus
- CAD/MI
- development of abdominal aortic aneurysms and aortic dissection
- 50% of HIV + patients have abnl echo
- HIV has a high affinity for myocardium
- Protease inhibitors in particular are problematic – advance atherosclerosis and diastolic dysfunction (25% HIV + have pericardial effusions)
- PCP less common now with advances in the pharmacologic treatment of the disease
- chronic PI therapy likely have hyperlipidemia (↑ LDL & ↓HDL)
HIV Systemic effects
Hematology
- drug toxicity/bone marrow suppression
- Leukopenia, lymphopenia, thrombocytopenia, anemia
check CBC & coags
HIV Systemic Effects
GI, Renal, Endocrine
- diarrhea, proctitis, GI bleeding, cholecystitis, anorexia, N&V, dysphagia (Candida albicans,CMV), esophagitis, Hepatitis B and C
- Nephropathy, ATN, nephrotic syndrome
- Adrenal insufficiency (end stages)
- Glucose intolerance (HAART)
review preop labs for electrolyte abnormalities, hypoalbuminemia
classes HAART therapy
anesthetic drug management
Currently there are 6 Categories
-
Nucleoside reverse transcriptase inhibitors
- Inhibition of CYP 450 system
- zidovudine + corticosteroids = severe myopathy, respiratory muscle dysfunction
-
Protease Inhibitors
- Inhibiton of CYP 450 3A4
-
fentanyl and versed have increased effects
- more sedation, confusion, respiratory depression
- start with low dose and titrate carefully
- fentanyl → clearance decreased by 67%
-
AVOID drugs w/active metabolites →LIFE THREATENING
- Meperidine → toxic metab → normeperedine (seizures)
- Amioderone →arrythmials →E1/2 = 29 days
- Diazepam → prolonged half life
-
Non-nucleoside reverse transcriptase inhibitors
- Delavirdine = Inhibits CYP 450
- (increased sedatives, warfarin, CCB)
-
Nevirapine = INDUCES CYP 540 by 98%
- go through NMB very fast
- Delavirdine = Inhibits CYP 450
- Integrase strand transfer inhibitors → appear well tolerated
-
Chemokine Receptor 5 antaonists and entry inhibitors
- also appear well tlerated
- may interact with the clearance and drug effects
HAART therapy
considerations in anesthesia
- institution of HAART within 6 months of anesthesia & surgery actually ↑ M&M
- Heart therapy effects every system in the body
-
Respiratory → opporunistic respiratory infections
- tracheobronchial great vessel compression and adenopathy (hemoptysis/difficult airway)
-
Cardiac → consider those on HAART as CAD risk (especially protease inhibitors)
- Cerebral vascular disease → stroke
- pericardidtis, pericardial effusions, dialated cardiomyopathy, endocardidits, pulm HTN, thromboembolism
- Development of abdominal aortic aneurism and aortic disection
- 50% have an abnormal ECHO
-
GI →
- N/V/D, proctitis, GI bleed, cholecyctitis, anorexia, dysphagia, candidia, CMV, Hep B & C
- Renal → Nephropathy, ATN, Nephrotic syndrome
-
Endocrine
- Adrenal insufficinecy → Steroids?
- Glucose intolerance (esp. protease inhibitors)
- Hematologic
- Leukopenia, lymphopenia, thrombocytopenia, anemia (CBC, coags)
-
Neurologic
- sensory neuropathies
- encephalopathy or AIDS dimetia complex
-
Respiratory → opporunistic respiratory infections
Ritonavir (Protease inhibitor) & Interactions with Anesthetic Drugs
-
Midazolam: ↑ effects
- sedation, confusion, respiratory depression
- Small carefully titrated IV dosing O.K. (just do it very slowly and carefully- working in very tiny incraments one consents are sighned)
-
Fentanyl: ↑ effects
- sedation, confusion, respiratory depression
- Start with low dose & titrate to pain
-
Avoid (pronounced effects → life threateningàdue to prolonged clearance)
- Meperidine → metabolized to normeperidine → which affects CNS (seizures) even with one dose may end up with a toxic dose
- Amiodarone (arrhythmias) → E½ life = 29 days - may not always think about this with ACLS but is something to keep in the back of your mind
- Diazepam → long ½ life
HIV and Lab results
-
CD4 counts
- low/ominous
- high/encouraging >500-700 mm3
- if low, maybe want them to go and change drug regimen prior to surgery
-
T lymphocyte counts
- low/ominous 200 cells/mg
- Viral load evaluates therapy efficacy but unclear significance to anesthetic outcome – wont tell us how they will do under anesthesia, drugs will still effect all other systems of these patients
- CBC
- BMP
- coagulation studies
- CXR
- EKG+/- ECHO
- PFTs
HIV
General Anesthesia
- Extensive use of volatile agents has refuted earlier caution against use
- Monitor closely for myocardial depression r/t anesthetic agents
- Biggest factor to consider = underlying pulmonary disease (avoid intubation if extensive)
- Carefully titrate anesthetics considering co-existing anemia, autonomic neuropathy, adrenal insufficiency, and upper airway obstruction/difficult airway w/supraglottic Kaposi’s sarcoma
- Be careful with Succinylcholine with peripheral neuropathy, myopathy, spinal cord involvement
- Long term effect of GA and opioid induced immunosuppresion unknown
- Immunosuppression from GA occurs within 15 minutes of induction and persists for 3-11 days. Psychological stress.
HIV
Regional
- Once controversial now routinely used– early concerns about spreading HIV to CSF unfounded
- Use of RA in parturients well studied – no abnormal neurologic, immunologic or infectious complications noted
- Contraindications:
- coagulopathy
- infection at the site of block placement
- focal neurologic lesions w/increased ICP
- Decreases IV opioid requirement (helps avoid issue of decreased IV opioid clearance w/protease inhibitors)
- Infection control, maintain sterile conditions!
- Epidural blood patch can be used to treat PDPH - try other methods 1st
HIV/AIDS
Preoperative Prepration
- Follow universal precautions (as with all patients)
- Routie sterilization procedures
- Sodium hypochlorite destroys HIV
- Careful reveiw of the progression of the disease process and organ involvement
- What is their durg regimen and side effects?
TB signs and symptoms Review
- Non Productive cough (74%)
- Weight loss (71%)
- Feaver and night sweats (30%)
- Malaise (30%)
- hemoptysis (bloody cough) and chest pain (19%)
TB first line treatment and side effects
Anti TB drugs have decreased mortality by 90%
Isoniazid and Rifampin are the most use combinations
-
Isoniazid
- Hepatotoxicity, possible renal toxicity, drug interactions
- peripheral neurotoxicity
-
Rifampin
- hepatotoxicity, renal toxicity, drug interactions
- GI upset, anemia, thrombocytopenia
-
Pyrazamide
- Hepatotoxicicty
- GI upset, arthralgia
- Ethambutol → occular neuritis
when can a TB patient have an elective surgery
- 3 negative sputum smears
- improving symptoms
- clear chest X-ray
! must meet ALL 3 requirements to go to surgery !
Prophylactic antibiotics in the Normal Patient
- The goal of therapy is prevention of surgical site infection
- They should be given within 1 hr before incision
- consider larger doses in obese pateints
- (2g of ancef instead of 1g)
- Redose if surgery > 4 hrs
- The antibiotic is tailored to resistance patterns
- of the local area
- and to the surgical procedure
besides antibiotics how else do you prevent infections
AVOID:
-
Hypothermia
- Cold pts develop infections at a much higher rate!
- They also bleed more!!!
-
Hypocarbia
- promotes infection causes vasoconstriction which decreases blood flow
- make sure you are not hyperventilating the patient
- Hypoxia
- Hyperoxia (free radical damage)
- Hyperglycemia
-
Blood transfusions
- if you can avoid it is its ideal – they are at higher risk to get an infection
Endocarditis prophilaxis - who gets it?
Patients who have:
- Artificial heart valves
- Prior history of endocarditis
- Some congenital cardiac malformations
- Cyanotic congenital heart disease (birth defects with O2 levels lower than normal), that has not been fully repaired, including children who have had a surgical shunts & conduits, or those with prosthetic device with a repaired
- A congenital heart defect that’s been completely repaired with artificial material or a device for the first six months after the repair procedure
- Repaired congenital heart disease with residual defects, such as persisting leaks or abnormal flow at or adjacent to a prosthetic patch or prosthetic device
- Damaged heart valves
- Hypertrophic cardiomyopathy
- A cardiac transplant which develops a problem in a heart valve
AND undergoing the following surgeries:
- Dental or oral with perforation of the oral mucosa likely (dental extractions)
- Invasive procedures of respiratory tract where respiratory mucosa perforated
- I.e. Tonsillectomy, adenoids, abscess drainage
- Procedure involving infection of GI/GU tract, skin/musculoskeletal tissue (not needed with routine procedures; colonoscopy, upper endoscopy, cystoscopy (removal of renal stones) or even bronchoscopy)
- Cardiac Surgery
- Hepatobiliary procedures with high risk of bacteremia
When and what do you give for endocarditis prophylaxis
give up to 2 hours after if patient misses pre-procedure
- Ampicillin 2 g IV (50 mg/kg pediatrics)
- Cefazolin (Ancef) 1 g IV (50 mg/kg pediatrics)
- Ceftriaxone (Rocephin) 1 g IV (50 mg/kg pediatrics)
If allergic to penicillins
- Clindamycin 600 mg IV (20 mg/kg IV pediatrics)
Precautions for emergency surgery in a patient with TB to minimize the risk of disease spread
-
Must wear N95 mask
- Patient → anytime they are outside the isolation room
- Health care workers → must be fit tested
- if unable to get adequate fit can be covered with a powered air purifying respirator
-
OR considerations
-
ORs never negative pressure = surgical site infection risk
- keep pt in neg. pressure room whenever possible
- An OR physically seperated from other areas is ideas
- OR doors should be shut
- Close the OR after the case until 99.9% turnover of air
- Patient will recover in the OR if the PACU does not have a negative pressure room
-
ORs never negative pressure = surgical site infection risk
- Anesthesia machine considerations
- Use a dedicated anesthia machine and ventilator
-
Filters
- High efficiency particulate filter→ between the y connector and the patient
- Bacterial filter→ on the exhalation limb (decreases ambient room exposure)
What are the main types of Allergic Reactions?
-
Type I
- IgE, mast cell basophils
- anaphylaxis and immune mediated hypersensitiveity
-
Type II
- IgG, IgM binding of antigen/drug
- alternate pathway, kinin or plasmin activation
- Cytotoxic-complement activation
- Usually manifests as hemolytic anemia, thrombocytopenia, neutropenia
-
Type III
- Dammage secondary due to immune complex formation or deposition
- Glomerularnephritis, vasculitis, arthralgias
-
Type IV
- T-lymphocyte mediated
- delayed hypersensitivity type
-
Chemical mediator with no antigen-antibody reaction
- mast cells and basophils activate in a non-immune mediated reaction
- this is an ANAPHALACTOID reaction
- examples MR, Meperidine, Morphine
Anaphylactoid Reaction
what is it and prophylaxis
Anaphylactoid Reaction
- manifests as histamine release
- Magnitude is related to total dose of drug administered & rate of infusion
- basophils release histamine in response to drugs such as muscle relaxants, opioids, & protamine
- Certain patients are susseptable to this type of reaction
- Hypotnesion is unlikley unless histamine concentration DOUBLES
Prohylaxis
-
Corticosteroids
- Decadron
-
H1 and H2 antagonist
- decrease histamine release
- Ranitidine, Benadryl
Anaphylaxis
- IgE mediated response
-
life threatening
- Extravasation of up to 50% of intravascular fluid volume into the EC space possible
-
CV issues are the first sign
- hypotension 1stsign (d/t vasodilation)
- bronchospasm - seen as increased PIP
- edema and airway swelling are late signs
Anaphylaxis: Common Offenders
-
Antimicrobial agents
- PCN → 90% of all allergic reactions & 97% of fatal reactions
-
Anesthetics
- All anesthetic agents can cause anaphylactic reactions with the exception of ketamine & benzos
- Thiopental has a low risk, but a very high mortality if they have an anaphylactic reaction
- Radiocontrast dyes
-
Foods
- I.e. peanuts
-
Insect venoms
- Bee allergy
Anaphylaxis: Anesthetic agents
- Opioids → D/t histamine release
- Local Anesthetics →esters more likely than amides
-
Induction agents →
- Consider ketamine to prevent reaction in high risk patients
-
Muscle relaxants
- 50-60% of intra-op anaphylaxis occurances
- actually much more likely to be casing than an antibiotic
- Volatile anesthetics
-
Antibiotics (10-15%) →
- Penicillin 90% of all allergic reactions + 97% of fatal reactions
- Blood → even with crossmatch (3% of patients)
- Dextran/Hetastarch
-
protamine
- seafood & salmon allergy
- NPH insulin
- Vascular grafts → DIC more than anaphylaxis
- Latex → 15% periop
Anaphylaxis: Differential Diagnosis
(first think…what could cause or be a manifestation of hypotension)
- Arrhythmia → Bradycardia → hypotension → decreased coronary profusion
- May look like an MI (ST changes?)
- CVA
- Hemmorage (may also cause hypotension)
-
Vasovagal reaction
- (anything that decreases venous return, uterine manipulation, SVC compression
- Pericardial tamponade
(Then think anything that couls cause decrease O2 or increaseCO2)
- Pulmonary embolism
- Pneumothorax (high peak inspiratory pressure)
- Asthma → shouldn’t produce immediate cardiovascular collapseAspiration
- Pulmonary edema
- Postextubation stridor
(Then the others that dont quite fit!)
- Venous Air embolism
- Medication overdose
- Sepsis
Anaphylaxis: Signs & Symptoms
- Flushing, urticaria (often missed d/t drapes)
- Rapid onset CV collapse often 1st sign →
- myocardial ischemia & dysrhythmias
-
Hypotension → up to 50% of the intravascular fluid moves to extracellular fluid secondary to capillary permeability changes + leukotrienes are negative inotropes)
- this happens within minutes
- Suspect anaphylaxis with sudden hypotension, +/- bronchospasm, following IV drug administration
- Bradycardia may occur especially with muscle relaxants
-
Difficult intubation → laryngeal edema
- (usually later but if they have an LMA/ or masking you will need to intubate immediately because it will get worse)
-
↑ PIP or inability to ventilate → bronchospasm
- first measure = ↑ inhaled anesthetics
- could use: Ketamine → propofol → epi
All could work in severe situation
anaphylaxis and antibiotic considerations
-
Most common offenders include:
- β-lactam (PCN, cephalosporins)
- quinolones
- sulfonamides
- vancomycin
- Prior to administration
- look at patients skin for pre-existing rash or skin condition
- If they develop a rash = may be a reaction to abx
-
Patients with a history of allergy (food, asthma, drugs)
- have increased incidence of anapylaxis
- may be genetic predisposition to increased IgE antibodies
-
If someone has a PCN allergy:
- they are 3-4x more likely to have an allergic reaction to ANY drug!
- NKDA/previous unevetntful exposure does not mean no allergy
- Often one exposure needed to make IgE
- It is the subsequent exposure that is the problem
Anaphylaxis: Prompt Intervention
-
Communication (let everyone know → surgeon, additional personnel)
- should stop the case immediately until stable again
- Stop administration of likely agent(s)
- Oxygenation
- Elevate legs if possible to promote blood flow to central circulation
- Volume infusion → need at least 10-25 ml/kg
- Colloids fluids (10 ml/kg) are preferred to crystalloid fluids (colloids may stay in the intravascular space more)
- Fluids boluses over 20 minutes
Anaphylaxis: Pharmacology
-
Epinephrine – (always always start with epi but sometimes it does fail)
- Blocks inflammatory mediator release from sensitized cells
- Restores cell membrane permeability
- β-agonist effect = relaxation of bronchial smooth muscle, ↑ BP & ↑ inotropy
- β2 → bronchodilation, ↓ histamine release from mast cells; also best to revers bronchospasm
- β1 → will help heart compensate
- α1 stimulation → vasoconstriction & restore vascular integrity
- Adult IV: 10 mcg-1 mg titrate q 1-2 minutes
- Start with 10 mcg then double with each repeated dose
- Children: 1-10 mcg/kg titrate q 1-2 minutes
Anaphylaxis: if resistant to epinephrine
-
Glucagon: 1-5 mg bolus + infusion 1-2.5 mg/hr
- ↑ cAMP promotes inotropic activity and helps with the bronchoconstriction
-
Norepinephrine: 0.05-0.1 mcg/kg/min
- will not help the bronchospasm situation – but will help in shunting blood to central areas –emergency drug
-
Vasopressin: 2-10 unit bolus + infusion 0.01-0.1 unit/min infusion
- moves blood to central circulation
Anaphylaxis: secondary Pharmacology
Not necessarily life saving but will help slow down or stop reaction causing anaphylaxis
-
β2 agonists
- albuterol if patient is still moving air
-
Histamine antagonism
- Diphenhydramine (IV)(0.5-1 mg/kg IV) with Ranitidine 50 mg IV → better for prevention than for tx.
- H1 & H2 need to be blocked together - has the best effect
-
Corticosteroids:
- Enhances β-effects of other agents
- Inhibits arachidonic acid release (↓ leukotrienes & prostaglandins)
- Reduced activation of the complement system
-
Hydrocortisone is favored 250 mg IV
- (Methylprednisolone also OK 80 mg IV)
- Children:
- hydrocortisone 50-100 mg &
- methylprednisolone 2 mg/kg
- Get them on board as soon as possible - wont see immediate effects
Septic Patient - Anesthesia Optimization Goals
Delay case if not an absolute emergency
- Normal temperature
- Normal blood glucose
- MAP >65 mmHg
- CVP 8-12 mmHg
- Hgb 7-9 g/dL
- Urine output adequate
-
Normalized pH
- correct metabolic acidosis - Plasmalite or Normasol- better compared to LR and NS because they are right at physiologic pH – it is maintained MUCH easier
- Mixed venous O2 Sat >70%
- Lower VT 6-8 ml/kg → to prevent barotrauma
- PIP <30
- Prevent additional infection
Septic pt and epiduals
Don’t even try
Absolute contraindication to do an epidural anesthesia
- Especially with hemodynamic instability → patient may not tolerate ↓ SVR
- Epidural abscess if bacteremic blood introduced into epidural space
Sepsis
What is it?
Anesthesia for the septic patient?
Sepsis Definition
- Sepsis is a large term representing a spectrum of diseases where there are pathogenic microorganisms in the body
- Severity depends on organ involvement and the extent of systemic inflammatory resposnse
Anesthesia management: Intervascular fluid and hemodynamic status guides management
-
Pre-op focus
- ABG, Vital Signs, mental status, vasopressors, sedation, pain management
- Need at least 2 large bore IVs
- Make sure PRBCs are in OR refrigerator (physically look!)
-
Monitors
- Standard +
- A-line PRE induction
- CVP/PA (lower threshold if TEE available)
Anesthesia for the septic patient
Induction
Goal = maintain SVR
- No specific ideal technique
- agents that will help maintain SVR
- Etomidate (conster the risk of adrenal supression)
- Ketamine
- Consider length of immobility before administering Succinycholine d/t possible hyerkalemian
Anesthesia for the septic patient
Maintinence
Goal is to maintain SVR
- No Ideal technique
-
Fluid resuscitation (bolus)
- crystalloind 500-1000mL
- colloid 300-500mL
-
Inotropic or vasoconstricter support if needed
- Epi
- Norepi (first on algorythm 0.05-0.5 mcg/kg/min)
- Dopamine
- Dobutamine
- Vasopressin
- Consider hydrocortisone for unresponsive shock
Anesthesia for the septic patient
Emergence
they will likely remain intubated and go to the ICU