Chapter 33 - Intraoperative management Flashcards
Anesthesia three components
1) analgesia 2) amnesia 3) relaxation
Analgesia definition
Absence of pain
Amnesia goal
block consciousness and memory formation
Relaxation goal
Block voluntary motor activity and suppress autonomic reflexes
Depth of sedation
TABLE 33.1
Clinical features of individual local anesthetic drugs
TABLE 33.2
Define Bier block
high dose of local anesthetic given IV in isolated limb with tourniquet to keep it contained
Clerance of ester and amide anesthetics
Ester = plasma cholinesterase Amide = liver metabolism
Toxic symptoms of local anesthetic
1) vertigo 2) tinnitus 3) anxiety/fear 4) tremors 5) seizure 6) coma 7) arrhythmia and myocardial depression
Drug that might mask early side effects of local anesthetic toxicity
Benzodiazepines
Reversal agents for moderate sedation
Naloxone = counter opiates Flumazenil = counter benzodiazepines
Things to monitor in moderate sedation
1) level of consciousness 2) oxygenation with pulse oximetry 3) arterial pressure with automated oscillometry q5 min 4) respiration for apnea monitor 5) ecg
common drugs for moderate sedation
TABLE 33.3
Dexmedetomidine key points
1) centrally acting 2) alpha 2 adrenergic agonist 3) decrease anxiety 4) provide pain relief and sedation 5) half life 2-3 hours 6) sympatholytic effects atropine standby as reversal
Ketamine key points
1) NMDA receptor antagonist 2) dissociative anesthetic 3) increase systemic and pulmonary pressure, HR, CO, myocardial oxygen requirement 4) avoid in heart disease, heart failure, CVA, epilepsy, psychotic illness, intracranial pressure
Initial dose of ketamine
0.5 mg/kg
Spinal and epidural anesthesia duration of action
lidocaine 60 min bupivacaine 100 min
Treatment of hypotension with spinal anesthesia
1) fluid resus 2) Tredelenburg position 3) inotropic/pressor
Complication of spinal anesthesia
1) postdural puncture headache 2) n/v with unopposed parasympathetic efferents 3) resp depression with COPD
Epidural anesthetic catheter duration
3-4 days
Spinal/epidural recommendation on holding anticoagulation and antiplatelet
TABLE 33.4
General anesthesia and temperature
1) inhibit sympathetic autonomic regulation 2) loss of vasoconstriction in periphery 3) loss of thermoregulation 4) dependent on therapeutic interventions with fluid and inotropes
Succinylcholine key points
1) depolarizing muscle relaxant 2) rapid onset short action 3) can cause malignant hypertermia, sepsis, arrhythmia, elevated intracranial pressure, increase serum potassium
Contraindication to succinylcholine use
1) large surface area burns 2) spinal cord injury 3) neuromuscular disease 4) cerebrovascular accident 5) chronic debility
Treatment of malignant hyperthermia
Dantrolene 2.5 mg/kg via large bore IV Hyperventilation on 100% O2 Cool patient before 38C Bicarb to correct metabolic acidosis Calcium chloride or calcium gluconate Sodium bicarb glucose and insulin for hyperkalemia
Absolute contraindication to using NO
1) respiratory compromise 2) air filled cavities (pneumothorax, pulmonary blebs, bowel obstruction)
Causes of propofol-associated hypotension
1) inhibition of sympathetic nervous system 2) impairment on baroreflex regulatory mechanism 3) dose-dependent decrease in potassium-induced tone in veins and arteries
Etomidate benefit
Does not affect sympathetic and autonomic reflex as propofol
Two common sedative-hypnotic agents that decrease cerebral blood flow and metabolic oxygen requirements
propofol etomidate
Etomidate side effect
inhibit cortisol production
Benefit of epidural
lower post-op pain score shorter intubation and mechanical ventilation rates of MI, GI complication, renal complication lower
Anesthesia in ruptured AAA key points
1) permissive hypotension 70-80 SBP 2) relaxation can relax tamponade 3) catch up needed once clamped 4) epidural for hemodynamically stable patients with contained ruptures
Spinal anesthesia benefit for PAD surgery
1) less early failure 2) less return to OR 3) less cardiac morbidity 4) less pneumonia compared to general anes
GALA study on carotid
General and local has similar outcome
ECG intraop
5 electrode system with 4 limb and 1 precordial lead V5
Normal gradient between end-tidal CO2 and PaCO2
5 mmHg affected by disease states
Rate of ulnar artery as dominant
90%
Reasons to avoid brachial catheters
1) poor collateralization 2) axillary sheath hematoma risk
CO calculation
heart rate x stroke volume determined by myocardial contractility and LVEDV
Central venous pressure key points
1) correlates with LV filling pressure in normal cardiopulm function 2) correlation weakened with positive pressure ventilation and patient positioning
Flow-directed balloon-tipped PA catheter uses
1) measure pulmonary artery diastolic pressure (PADP) 2) measure pulmonary capillary wedge pressure (PCWP) 3) sample mixed venous blood to calculate total body oxygen delivery DO2 and total body oxygen consumption VO2
Minimally invasive hemodynamic monitoring systems
1) FloTrac sensor 2) ProAQT sensor with Pulsioflex monitor 3) LidCO rapid system cold fluid or lithium dilution
Strategies to reduce incidence of surgical site infection
1) give prophylaxis within 1 hour of incision 2) dose adjust for body weight 3) ensure redosing as needed 4) short post-op course < 24 hr 5) vancomycin and clindamycin were appropriate substitutes in beta-lactam allergy 6) not used in angiogram, angioplasty, bare metal stent, venous procedure, thrombolysis and closure device only
Adrenergic agents around surgery
1) continue betablocker 2) start therapy at least 7 days prior to surgery and not day of surgery
Contraindication to beta blocker
1) asthma 2) sick sinus syndrome 3) second-third degree heart block
Normothermia definition
36-38 C
Physiologic response to hypothermia in awake patient
1) sympathetic activation 2) increased norepinephrine 3) shivering 4) increased metabolic rate 5) increased oxygen consumption 6) increased MAP
Post-op hyperglycemia and infection risk
30% for every 40 point increase from normal 110 mg/dl
Goal target for post-op blood surgar
< 200 mg/dl
Half life of heparin
30-90 min
Protamine risk of anaphylaxis
3%
Argatroban dose in HIT
350 mcg/kg over 3-5 min then infusion 25 mcg/kg/min
Bivalirudin dose in HIT
0.75 mg/kg bolus then 1.75 mg/kg/hr
Bivalirudin reversal
Factor VIIa hemodialysis
Dabigatran Brand name MOA half life metabolism coag assay reversal
Pradaxa DTI 12-17 hours 85% renal excretion TT, ECT, aPTT Reversal: HD, activated charcoal, PCC, Factor 7a Specific: idarucizumab (Praxbind)
Dose of praxbind
5 g IV humanized monoclonal antibody fragment
Rivaroxaban Brand name MOA half life metabolism coag assay reversal
Xarelto Factor 10a block 5-9 hours 66% renal; 33% hepatic Anti-Xa assay, PT, aPTT Reversal: activated charcoal, 4 factor PCC, aPCC Specific: clinical trials only
Apixaban Brand name MOA half life metabolism coag assay reversal
Eliquis Factor 10a block 7-14 hours 66% hepatic; 33% renal anti Xa assay aPTT Reversal: activated charcoal, 4 factor PCC, aPCC Specific: clinical trial
Fondaparinux Brand name MOA half life metabolism coag assay reversal
Arixtra antithrombin III 17-21 hours renal only anti-factor Xa Reversal: rFVIIa, aPCC
Reason for antiplatelet after stent
Endothelialization of stent 1 month after BMS 12 months after DES
Desmopression key points
1) V2 receptor agonist analogue of arginine vasopressin 2) enhance platelet unction through stimulated release of vWF from endothelial cells 3) 2.4x risk of MI
Initial physiologic response to anemia
1) increase stroke volume (less viscosity and less impedance to ventricular ejection) 2) increase venous return (less peripheral resistance)
Transfusion related acute lung injury - diagnosis
1) hypoxemia with ratio of PaO2//FiO2 < 40 kpa (300 mmHg) 2) bilaterla lung infiltrates 3) pulmonary vascular overload
Incidence of TRALI
1.12% per unit of blood can be as high as 8%
Mortality of TRALI
5-45%
Mechanism of TRALI
Donor antibodies to recipient leukocyte antigen –> activation and lung injury Possible two hit hypothesis due to sensitization by insult
Treatment of TRALI
1) stop transfusion 2) resp support 3) lung protective ventilation
Transfusion associated circulatory overload rate
1-8%
TACO diagnosis
1) Hydrostatic pulmonary edema in presence of increased pulmonary and left atrial pressure 2) Bilateral infiltrates 3) elevated BNP (78%)
Treatment of TACO
1) telemetry 2) O2 3) elevated head 4) noninvasive positive pressure ventilation 5) diuresis 6) vasodilation with nitrate 7) renal replacement
Rate of bacterial contamination in platelets
1 in 1000-2000
Rate of bacterial contamination in RBC and type of bacteria
Yersinia enterocolitica 1 in 1000000
Hep B virus transmission rate
1 in 50000-150000
Risk of ABO incompatible blood given
1 in 1000000
Transfusion-related immunomodulation (TRIM)
downregulation of immune system response after transfusion
Transfusion triggers on HGB
TABLE 33.6
Strategies to limit transfusion
1) preoperative treatment with erythropoietin 2) preoperative autologous blood donation 3) acute normovolemic hemodilution 4) intraoperative autologous blood recovery and transfusion (if suspected > 5 unit loss 1.5L)
