Aortic Stenosis and Neuraxial Anesthesia


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Aortic Stenosis and Neuraxial Anesthesia

  1. 1. PBLD #8 Aortic Stenosis and Neuraxial Anesthesia Until 30 June 2005: John Butterworth, MD Department of Anesthesiology Wake Forest University School of Medicine Winston-Salem, North CarolinaSee: anesthesiology/research/ faculty_presentations.htm
  2. 2. PBLD #8 Aortic Stenosis and Neuraxial Anesthesia After 1 July 2005: John Butterworth, MD Department of Anesthesiology Indiana University School of Medicine Indianapolis, Indiana See: anesthesiology/research/ faculty_presentations.htm
  3. 3. Clinical CaseClinical Case • 78 year old woman with known aortic valvular78 year old woman with known aortic valvular stenosis requires hemiarthroplasty of left hipstenosis requires hemiarthroplasty of left hip for avascular necrosisfor avascular necrosis • Mild dementiaMild dementia • Mild chronic renal insufficiency (CrCl <50Mild chronic renal insufficiency (CrCl <50 ml/min)ml/min) • Preoperative echocardiogram showsPreoperative echocardiogram shows – Calcified aortic valve – Peak gradient 60 mm Hg – Valve area 0.5 cm2 – Severe concentric left ventricular hypertrophy (septum is 1.5 cm thick)
  4. 4. What are the indications forWhat are the indications for aortic valve replacement inaortic valve replacement in patients with aorticpatients with aortic stenosis?stenosis?
  5. 5. Indications for AVR inIndications for AVR in Patients with ASPatients with AS • SymptomsSymptoms – Angina – Dyspnea – Arrhythmias • Gradient increasing and >50 mmHgGradient increasing and >50 mmHg • Moderate AS in patient requiring otherModerate AS in patient requiring other cardiac surgery (e.g. CAB or MVR)cardiac surgery (e.g. CAB or MVR)
  6. 6. What are the AnestheticWhat are the Anesthetic Goals for a PatientGoals for a Patient Undergoing AVR?Undergoing AVR?
  7. 7. Anesthetic Goals for aAnesthetic Goals for a Patient Undergoing AVRPatient Undergoing AVR • Avoid hypotensionAvoid hypotension – Critical importance of coronary perfusion perfusion pressure – Potential for difficult resuscitation • Avoid tachycardiaAvoid tachycardia • Lack of awareness, analgesia,Lack of awareness, analgesia, immobility, etc.immobility, etc.
  8. 8. What Would be AppropriateWhat Would be Appropriate Monitoring DuringMonitoring During Anesthesia for AVR in aAnesthesia for AVR in a Patient with AS?Patient with AS?
  9. 9. Appropriate MonitoringAppropriate Monitoring During Anesthesia for AVRDuring Anesthesia for AVR in a Patient with ASin a Patient with AS • Arterial line before inductionArterial line before induction • Large bore intravenous lineLarge bore intravenous line • Vasopressor infusion ready for useVasopressor infusion ready for use (some will initiate the infusion before(some will initiate the infusion before induction)induction) • Central line vs. PA lineCentral line vs. PA line • TEETEE
  10. 10. What would be the benefitsWhat would be the benefits of regional anesthesia inof regional anesthesia in this patient?this patient?
  11. 11. Benefits of regionalBenefits of regional anesthesia in this patientanesthesia in this patient • Simple anestheticSimple anesthetic • Reduced postoperative deliriumReduced postoperative delirium • PotentialPotential for:for: – Reduced bleeding – Reduced DVT – Reduced pulmonary emboli – Better outcome
  12. 12. Reduction of morbidity andReduction of morbidity and mortality with epidural or spinalmortality with epidural or spinal anesthesia: meta analysisanesthesia: meta analysis • 141 trials, n=9559141 trials, n=9559 • Neuraxial blockNeuraxial block significantlysignificantly reduced risk ofreduced risk of death (0.7), DVTdeath (0.7), DVT (0.56), PE (0.45),(0.56), PE (0.45), pneumonia (0.61),pneumonia (0.61), incidence ofincidence of transfusion of 2 ortransfusion of 2 or more units (0.5)more units (0.5) 0 1 2 3 4 5 6 Die DVT PE 2+U RA GA % incidence Rodgers. BMJ 2000;321:1-12
  13. 13. What would be the benefitsWhat would be the benefits of general anesthesia in thisof general anesthesia in this patient?patient?
  14. 14. Benefits of generalBenefits of general anesthesia in this patientanesthesia in this patient • Control of airwayControl of airway • No need for sedation of demented patientNo need for sedation of demented patient • Can (theoretically) avoid vasodilatingCan (theoretically) avoid vasodilating anesthetic drugsanesthetic drugs • Can perform intraoperative TEE to reassessCan perform intraoperative TEE to reassess valve and ventricular filling/functionvalve and ventricular filling/function • No need to explain to fellow anesthesiologistsNo need to explain to fellow anesthesiologists why you chose regionalwhy you chose regional
  15. 15. What are the cardiovascularWhat are the cardiovascular effects of spinal andeffects of spinal and epidural anesthesia?epidural anesthesia?
  16. 16. Cardiovascular physiology ofCardiovascular physiology of spinal anesthesiaspinal anesthesia • Sympathetic nervous systemSympathetic nervous system – Age effects – Venous pooling – Reduced peripheral resistance – Indirect myocardial effect = bradycardia • Treatment of hypotensionTreatment of hypotension
  17. 17. Age effects on systolic bloodAge effects on systolic blood pressurepressureIncreasing age associates with an increasing incidence of hypotension Dohi et al. Anesthesiology 1979;50:319-23
  18. 18. Lidocaine spinal causes bloodLidocaine spinal causes blood pooling in abdomen and legspooling in abdomen and legs -20 -15 -10 -5 0 5 10 LVEDV LVR SPLN KID MES LEGS % Rooke et al. Anesth Analg 1997;85:99-105
  19. 19. Spinal anesthesia increases venousSpinal anesthesia increases venous pooling and reduces arterial resistancepooling and reduces arterial resistance during canine cardiopulmonary bypassduring canine cardiopulmonary bypass • Total spinal anesthesia with 20 mg tetracaineTotal spinal anesthesia with 20 mg tetracaine in cisterna magnain cisterna magna • Cardiac output (CPB flow) held constantCardiac output (CPB flow) held constant • Volume of CPB venous reservoir declines 5.6Volume of CPB venous reservoir declines 5.6 ±± 0.9 ml/kg (venous pooling)0.9 ml/kg (venous pooling) • Mean arterial pressure declines 31Mean arterial pressure declines 31 ±± 5%5% (reduced systemic vascular resistance)(reduced systemic vascular resistance) Butterworth. Anesth Analg 1986;65:612-6; Butterworth. Anesth Analg 1987;66:209-14
  20. 20. Bradycardia and hypotensionBradycardia and hypotension complications after SPAcomplications after SPA • In non-OB pts, risk ofIn non-OB pts, risk of hypotension 33%;hypotension 33%; bradycardia 13%bradycardia 13% • Odds ratios forOdds ratios for hypotension: >T5: 3.8,hypotension: >T5: 3.8, >40 yrs old: 2.5, baseline>40 yrs old: 2.5, baseline SAP <120 mm Hg: 2.4,SAP <120 mm Hg: 2.4, LP above L3-4: 1.8LP above L3-4: 1.8 • ORs for bradycardia:ORs for bradycardia: ββARBs: 2.9 , >T5: 1.7,ARBs: 2.9 , >T5: 1.7, baseline HR <60: 4.9,baseline HR <60: 4.9, prolonged PR: 3.2prolonged PR: 3.2 0 1 2 3 4 5 >T5 <60 PR Hypo Brady Carpenter. Anesthesiology 1992;76:906-16 Liu. Reg Anesth 1995;20:41-4 Odds Ratios
  21. 21. Failure to prevent SPA hypotension:Failure to prevent SPA hypotension: crystalloid (n=29), colloid (n=28), or nocrystalloid (n=29), colloid (n=28), or no prehydration (n=28)prehydration (n=28) 0 10 20 30 40 50 60 70 Hypot Ephed N or V Cry 0.5 L Col 0.5 L Nil % Buggy et al Anesth Analg 1997;84:106-10
  22. 22. ββ-, but not-, but not αα-adrenergic agonists reverse-adrenergic agonists reverse venous pooling during spinalvenous pooling during spinal anesthesiaanesthesia Butterworth. Anesth Analg 1986;65:612-6Butterworth. Anesth Analg 1986;65:612-6 μg/kg/min mg/kgμg/kg/min
  23. 23. Epinephrine preferable toEpinephrine preferable to phenylephrine for hypotension afterphenylephrine for hypotension after hyperbaric tetracaine spinal anesthesiahyperbaric tetracaine spinal anesthesia • 14 patients: 10 mg hyperbaric tetracaine14 patients: 10 mg hyperbaric tetracaine • Transthoracic echo estimation of SVTransthoracic echo estimation of SV • Treatment when SAP decreased 15%Treatment when SAP decreased 15% • Epi (4 µg + 50 ng/kg/min) & Phenyl (40Epi (4 µg + 50 ng/kg/min) & Phenyl (40 µg + 0.5 µg/kg/min), randomized,µg + 0.5 µg/kg/min), randomized, double-blind, cross-over designdouble-blind, cross-over design • Epi increases stroke volume andEpi increases stroke volume and maintains HR; Phenyl decreases HRmaintains HR; Phenyl decreases HR Brooker et al Anesthesiology 1997;86:797-805
  24. 24. Brooker et al Anesthesiology 1997;
  25. 25. Brooker et al Anesthesiology 1997; 86:797-805
  26. 26. Effects of epidural anesthesiaEffects of epidural anesthesia on the cardiovascular systemon the cardiovascular system • Sympathetic blockSympathetic block – Venous pooling = ↓apparent blood volume – ↓Peripheral resistance • Effects of epinephrine in LA solutionsEffects of epinephrine in LA solutions • Dermatomal level of anesthesiaDermatomal level of anesthesia determines hemodynamic effectsdetermines hemodynamic effects • Differing hemodynamic effects ofDiffering hemodynamic effects of thoracic vs. lumbar epidural anesthesiathoracic vs. lumbar epidural anesthesia
  27. 27. Pooling of blood in legs afterPooling of blood in legs after lumbar epidural anesthesialumbar epidural anesthesia -10 -5 0 5 10 Thorax Abd Arms Legs % Arndt. Anesthesiology 1985;63:616-23
  28. 28. Effect of level of epiduralEffect of level of epidural anesthesia on CV responsesanesthesia on CV responses • Volunteers (n=10)Volunteers (n=10) received 2% lido LEAreceived 2% lido LEA (11-20 mg/kg) to(11-20 mg/kg) to produce increasingproduce increasing dermatomal levels ofdermatomal levels of anesthesiaanesthesia • Increased arm bloodIncreased arm blood flow (cervicalflow (cervical sympathectomy) onlysympathectomy) only when block >T2when block >T2 -20 -15 -10 -5 0 5 10 8 6 4 >2 MAP ABF LBF Thoracic dermatome % change from baseline Bonica. Anesthesiology 1970;33:619-26
  29. 29. TEA vs LEA CV effectsTEA vs LEA CV effects ARM BF LEG BF CARD OUTPT MAP -12% -1% +47% +21% -9% +7% -35% +510% TEA vs. LEA: differing effects on regional blood flow
  30. 30. Do either the baricity or theDo either the baricity or the specific the local anestheticspecific the local anesthetic make a difference duringmake a difference during spinal anesthesia?spinal anesthesia?
  31. 31. Choices in spinal anesthesiaChoices in spinal anesthesia • Needle size and styleNeedle size and style • Puncture sitePuncture site • Local anesthetic species and doseLocal anesthetic species and dose • Baricity of local anesthetic solutionBaricity of local anesthetic solution • Patient position after injectionPatient position after injection • Additives (opioids, vasoconstrictors, clonidine,Additives (opioids, vasoconstrictors, clonidine, neostigmine)neostigmine) • Continuous spinal or combined spinal-epiduralContinuous spinal or combined spinal-epidural
  32. 32. Local anesthetic choices forLocal anesthetic choices for spinal anesthesiaspinal anesthesia • Hyperbaric solutionsHyperbaric solutions – Procaine 5% (<45 min) – Lidocaine 1.5-5% (<1 h) – Tetracaine 0.5% (<3 h) – Tetracaine 0.5% + epi (<4 h) – Bupivacaine 0.75% (<3 h) • Isobaric solutionsIsobaric solutions – Bupivacaine 0.5% (<3 h) – Lidocaine 2% (<2 h) – Tetracaine 0.5% (<3 h) – Meperidine 2.5% (<2 h) – Mepivacaine 1-2% • Hypobaric solutionsHypobaric solutions – Tetracaine 0.1-0.2% (<3 h) – Bupivacaine 0.5% + fentanyl 20 μg
  33. 33. Local anesthetic baricity andLocal anesthetic baricity and spinal anesthesiaspinal anesthesia • Hyperbaric solutionsHyperbaric solutions – Density > CSF – Flows to dependent sites – Sitting⇒”Saddle” block’ – Supine⇒thoracic level • Isobaric solutionsIsobaric solutions – Density ≅ CSF – No effect of position – Long duration • Hypobaric solutionsHypobaric solutions – Density < CSF – Flows from dependent sites – Sitting ⇒ ?total spinal – Supine ⇒ inconsistent spread – Jack-knife (Buie) ⇒sacral block – Lateral ⇒ block of superior side
  34. 34. Hyperbaric Isobaric Hypobaric Sensorydermatome Time (min) Greater dermatomal spread with hyperbaric than hypobaric or isobaric bupivacaine in supine patients Van Gessel EF. Anesth Analg 1991;72:779-84
  35. 35. Effects of local anestheticEffects of local anesthetic dose on spinal anesthesiadose on spinal anesthesia • Dose of hyperbaric LA has almostDose of hyperbaric LA has almost nono influenceinfluence on dermatomal spread, even inon dermatomal spread, even in pregnancy (tetracaine 10 or 15 mgpregnancy (tetracaine 10 or 15 mg blocks comparable dermatomes)blocks comparable dermatomes) ∀ ↑↑dose =dose = ↓↓onset,onset, ↑↑duration, andduration, and ↑↑"quality" of block (hyperbaric,"quality" of block (hyperbaric, hypobaric, and isobaric)hypobaric, and isobaric)
  36. 36. Combined spinal-epidural (CSE)Combined spinal-epidural (CSE) • Rapidly increasing popularityRapidly increasing popularity • AdvantagesAdvantages: rapid onset, ability to titrate: rapid onset, ability to titrate or prolong block,or prolong block, ↓↓spinal drug dosagespinal drug dosage • DisadvantagesDisadvantages: catheter migration,: catheter migration, ↓↓reliability of test dosing, ↑failure rate (?)reliability of test dosing, ↑failure rate (?) • Needle through needle vs double segmentNeedle through needle vs double segment • Useful forUseful for:: – OB analgesia – Ambulatory anesthesia – Postop pain management after spinal anesthetic
  37. 37. Continuous spinalContinuous spinal anesthesiaanesthesia • Analogous to continuous epidural anesthesiaAnalogous to continuous epidural anesthesia • Permits long duration spinal anesthesiaPermits long duration spinal anesthesia • No special safety problemsNo special safety problems providedprovided that therethat there is free flow of CSF through catheter and theis free flow of CSF through catheter and the catheter tip is not misplaced in a root sleevecatheter tip is not misplaced in a root sleeve • Requirement for larger needleRequirement for larger needle ↑↑PDPH riskPDPH risk • 27g catheters formerly available associated27g catheters formerly available associated with neurological deficits (maldistribution orwith neurological deficits (maldistribution or restricted distribution of 5% lidocaine?)restricted distribution of 5% lidocaine?)
  38. 38. How case was managedHow case was managed • Arterial line placedArterial line placed • CSE techniqueCSE technique • Hyperbaric bupivacaine 5 mg + 20Hyperbaric bupivacaine 5 mg + 20 µgµg fentanylfentanyl • Lateral positionLateral position • Phenylephrine dripPhenylephrine drip • Patient now in PACU, will you start PCEAPatient now in PACU, will you start PCEA infusion with bupivacaine-morphine?infusion with bupivacaine-morphine?
  39. 39. How case was managedHow case was managed • You have got to be kidding!You have got to be kidding!