Immunity disorders & infections Flashcards
Zidovudine + corticosteroids
severe myopathy
respiratory muscle dysfunction
Nucleoside reverse transcriptase inhibitors
considerations
ex: Lemuvidine, Zidovudine (Nucleoside reverse transcriptase inhibitors)
- inhibition cytochrome P450 (zidovudine + corticosteroids = severe myopathy including respiratory muscle dysfunction)
- Lactic acidosis is a huge issue – may have a lower threshold for getting a blood gas
- Nausea, diarrhea, myalgia,
- ↑ LFTS, pancreatitis,
- peripheral neuropathy (possible nerve injury),
- renal toxicity,
- marrow suppression,
- anemia
HIV drug that decreases fentanyl clearance
Protease inhibitors (ritonavir)
- inhibition of CYP450 3A4
- ↓ fentanyl clearance ~ 67%
- titrated fentany more conservatively
- increased effects of versed
- ↓ fentanyl clearance ~ 67%
- AVOID: meperidine, amiodarone, diazepam in all pts on PI therapy!
Protease inhibitors (ritonavir)
considerations
- Hyperlipidemia
- glucose intolerance → higher blood glucose levels
- abnormal fat distribution
- altered LFTs
- inhibition of CYP450 3A4
Non-nucleoside analog reverse transcriptase inhibitors
considerations
- Delavirdine inhibits cytochrome P450
- may ↑ concentrations
- sedatives
- antiarrhythmics
- warfarin
- Ca2+ channel blockers
- may ↑ concentrations
- Nevirapine induces cytochrome P450 by 98%!
- Make sure you are checking things like NMB
Integrase strand transfer inhibitors
considerations
appear well tolerated
Chemokine receptor 5 antagonists & entry inhibitors
considerations
interact with midazolam altering clearance & drug effect
HAART therapy and anesthesia
institution of HAART within 6 months of anesthesia & surgery actually ↑ M&M
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 signed)
- Fentanyl: ↑ effects
- sedation, confusion, respiratory depression
- Start with low dose & titrate to pain
-
Avoid (pronounced effects → life threatening due 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
sterilization product that destroys HIV
Na+ hypochlorite
HIV and Lab results
- CD4 counts
- low/ominous <200 mm3;
- 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
TB drugs that are hepatotoxic
isonazid
Rifampin
Pyrazinamide
TB drugs that are hepatotoxic AND renal toxic and have significant drug interactions
Isoniazid
Rifampin
** these are also the most used**
Isoniazid adverse rxn
Hepatotoxicity
peripheral neurotoxicity
possible renal toxicity
drug interactions
Rifampin adverse rxn
- Hepatotoxicity
- renal toxicity
- anemia
- thrombocytopenia
- gastrointestinal upset
- drug interactions
Pyrazinamide adverse rxn
Hepatotoxicity
gastrointestinal upset
arthralgia
Ethambutol adverse rxn
Ocular 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 !
when do you give antibiotics?
- normal pt: within 1 hr before surgery
- redose if surgery > 4 hrs
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
- concerning for 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)
Type I allergic rxn
Antigen-Antibody
- IgE, mast cells, basophils degranulation → anaphylaxis
- immune-mediated hypersensitivity
Type II allergic rxn
Cytotoxic-Complement Activation
- IgG or IgM binding of the antigen-drug
- alternate pathway, kinin or plasmin activation
- Type II usually manifest as hemolytic anemia, thrombocytopenia, neutropenia
Type III allergic rxn
Damage secondary to immune complex formation or deposition
Glomerulonephritis, vasculitis, arthralgias
Type IV allergic rxn
T lymphocyte mediated
delayed hypersensitivity type
Chemical Mediator allergic rxn
Chemical Mediator with no antigen-antibody reaction
mast cells & basophils activate in a non-immune reaction → anaphylactoid
I.e. MR, meperidine, morphine, etc.
Anaphylactoid Reaction
manifests as histamine release
related to total dose of drug administered & rate of infusion
ex: muscle relaxants, opioids, & protamine
Anaphylactoid Reaction prophylaxis
- Corticosteroid
- H1 & H2 receptor antagonist
I.e. decadron, benadryl, ranitidine
Anaphylaxis
- IgE mediated response
- life threatening
- Extravasation of up to 50% of intravascular fluid volume into the EC space possible
- hypotension 1stsign
- 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
- Muscle relaxants
- 50-60% of intra-op anaphylaxis occurances
- actually much more likely to be casing than an antibiotic
- protamine
- seafood & salmon allergy
- NPH insulin
- Induction agents
- Consider ketamine to prevent reaction in high risk patients
- Antibiotics (10-15%)
- Volatile anesthetics
- Opioids
- D/t histamine release
- Local Anesthetics
- esters more likely than amides
- Blood → even with crossmatch
- 3% of patients
- Dextran/Hetastarch
- Vascular grafts
- DIC more than anaphylaxis
- Latex
- 15% periop
Anaphylaxis: Differential Diagnosis
- Pulmonary embolism
- Pneumothorax – high peak inspiratory pressure
- AMI
- CVA
- Hemorrhage
- Aspiration
- Pulmonary edema
- Venous Air embolism
- Vasovagal reaction
- Medication overdose
- Asthma → shouldn’t produce immediate cardiovascular collapse
- Arrhythmia → one of the first signs from the muscle reactants these patients could become very bradycardic → may have a loss of profusion to the coronaries and look like an MI
- Pericardial tamponade
- Postextubation stridor
- Sepsis
Anaphylaxis: Signs & Symptoms
- Rapid onset CV collapse often 1st sign → myocardial ischemia & dysrhythmias
-
Hypotension → up to 50% of the ICF moves to ECF 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 this is if it is in the later phase – keep in mind if they have an LMA or are masking you will need to intubate immediately because it will get worse and worse)
- ↑ PIP or inability to ventilate → bronchospasm
- Flushing, urticaria
Ketamine → propofol → epi
All could work in severe situation
anaphylaxis
most common offending abx
- β-lactam
- Penicillin, Amoxicillin, Ampicillin, Meticillin
- quinolones
- Ciprofloxacin, Levofloxacin, Ofloxacin, Moxifloxacin
- sulfonamides
- vancomycin
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 reverse bronchospasm
- β1 → will help heart compensate &↑ inotropy
- 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
- Diphenhydramine (IV)(0.5-1 mg/kg IV) with Ranitidine 50 mg IV → better for prevention than for tx.
- 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
- 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 cmH2O
- Hgb 7-9 g/dL
- 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
