• Like

Loading…

Flash Player 9 (or above) is needed to view presentations.
We have detected that you do not have it on your computer. To install it, go here.

Aortic Stenosis and Neuraxial Anesthesia

  • 1,872 views
Uploaded on

 

  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Be the first to comment
No Downloads

Views

Total Views
1,872
On Slideshare
0
From Embeds
0
Number of Embeds
0

Actions

Shares
Downloads
44
Comments
0
Likes
1

Embeds 0

No embeds

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
    No notes for slide

Transcript

  • 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 Carolina See: http://www1.wfubmc.edu/ anesthesiology/research/ faculty_presentations.htm
  • 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: http://www1.wfubmc.edu/ anesthesiology/research/ faculty_presentations.htm
  • 3. Clinical Case
    • 78 year old woman with known aortic valvular stenosis requires hemiarthroplasty of left hip for avascular necrosis
    • Mild dementia
    • Mild chronic renal insufficiency (CrCl <50 ml/min)
    • Preoperative echocardiogram shows
      • Calcified aortic valve
      • Peak gradient 60 mm Hg
      • Valve area 0.5 cm 2
      • Severe concentric left ventricular hypertrophy (septum is 1.5 cm thick)
  • 4. What are the indications for aortic valve replacement in patients with aortic stenosis?
  • 5. Indications for AVR in Patients with AS
    • Symptoms
      • Angina
      • Dyspnea
      • Arrhythmias
    • Gradient increasing and >50 mmHg
    • Moderate AS in patient requiring other cardiac surgery (e.g. CAB or MVR)
  • 6. What are the Anesthetic Goals for a Patient Undergoing AVR?
  • 7. Anesthetic Goals for a Patient Undergoing AVR
    • Avoid hypotension
      • Critical importance of coronary perfusion perfusion pressure
      • Potential for difficult resuscitation
    • Avoid tachycardia
    • Lack of awareness, analgesia, immobility, etc.
  • 8. What Would be Appropriate Monitoring During Anesthesia for AVR in a Patient with AS?
  • 9. Appropriate Monitoring During Anesthesia for AVR in a Patient with AS
    • Arterial line before induction
    • Large bore intravenous line
    • Vasopressor infusion ready for use (some will initiate the infusion before induction)
    • Central line vs. PA line
    • TEE
  • 10. What would be the benefits of regional anesthesia in this patient?
  • 11. Benefits of regional anesthesia in this patient
    • Simple anesthetic
    • Reduced postoperative delirium
    • Potential for:
      • Reduced bleeding
      • Reduced DVT
      • Reduced pulmonary emboli
      • Better outcome
  • 12. Reduction of morbidity and mortality with epidural or spinal anesthesia: meta analysis
    • 141 trials, n=9559
    • Neuraxial block significantly reduced risk of death (0.7), DVT (0.56), PE (0.45), pneumonia (0.61), incidence of transfusion of 2 or more units (0.5)
    % incidence Rodgers. BMJ 2000;321:1-12
  • 13. What would be the benefits of general anesthesia in this patient?
  • 14. Benefits of general anesthesia in this patient
    • Control of airway
    • No need for sedation of demented patient
    • Can (theoretically) avoid vasodilating anesthetic drugs
    • Can perform intraoperative TEE to reassess valve and ventricular filling/function
    • No need to explain to fellow anesthesiologists why you chose regional
  • 15. What are the cardiovascular effects of spinal and epidural anesthesia?
  • 16. Cardiovascular physiology of spinal anesthesia
    • Sympathetic nervous system
      • Age effects
      • Venous pooling
      • Reduced peripheral resistance
      • Indirect myocardial effect = bradycardia
    • Treatment of hypotension
  • 17. Age effects on systolic blood pressure Increasing age associates with an increasing incidence of hypotension Dohi et al. Anesthesiology 1979;50:319-23
  • 18. Lidocaine spinal causes blood pooling in abdomen and legs % Rooke et al. Anesth Analg 1997;85:99-105
  • 19. Spinal anesthesia increases venous pooling and reduces arterial resistance during canine cardiopulmonary bypass
    • Total spinal anesthesia with 20 mg tetracaine in cisterna magna
    • Cardiac output (CPB flow) held constant
    • Volume of CPB venous reservoir declines 5.6  0.9 ml/kg (venous pooling)
    • Mean arterial pressure declines 31  5% (reduced systemic vascular resistance)
    Butterworth. Anesth Analg 1986;65:612-6; Butterworth. Anesth Analg 1987;66:209-14
  • 20. Bradycardia and hypotension complications after SPA
    • In non-OB pts, risk of hypotension 33%; bradycardia 13%
    • Odds ratios for hypotension: >T5: 3.8, >40 yrs old: 2.5, baseline SAP <120 mm Hg: 2.4, LP above L3-4: 1.8
    • ORs for bradycardia:  ARBs: 2.9 , >T5: 1.7, baseline HR <60: 4.9, prolonged PR: 3.2
    Carpenter. Anesthesiology 1992;76:906-16 Liu. Reg Anesth 1995;20:41-4 Odds Ratios
  • 21. Failure to prevent SPA hypotension: crystalloid (n=29), colloid (n=28), or no prehydration (n=28) % Buggy et al Anesth Analg 1997;84:106-10
  • 22.
    •  -, but not  -adrenergic agonists reverse venous pooling during spinal anesthesia
    • Butterworth. Anesth Analg 1986;65:612-6
    μ g/kg/min mg/kg μ g/kg/min
  • 23. Epinephrine preferable to phenylephrine for hypotension after hyperbaric tetracaine spinal anesthesia
    • 14 patients: 10 mg hyperbaric tetracaine
    • Transthoracic echo estimation of SV
    • Treatment when SAP decreased 15%
    • Epi (4 µg + 50 ng/kg/min) & Phenyl (40 µg + 0.5 µg/kg/min), randomized, double-blind, cross-over design
    • Epi increases stroke volume and maintains HR; Phenyl decreases HR
    Brooker et al Anesthesiology 1997;86:797-805
  • 24. Brooker et al Anesthesiology 1997; 86:797-805
  • 25. Brooker et al Anesthesiology 1997; 86:797-805
  • 26. Effects of epidural anesthesia on the cardiovascular system
    • Sympathetic block
      • Venous pooling = ↓ apparent blood volume
      • ↓ Peripheral resistance
    • Effects of epinephrine in LA solutions
    • Dermatomal level of anesthesia determines hemodynamic effects
    • Differing hemodynamic effects of thoracic vs. lumbar epidural anesthesia
  • 27. Pooling of blood in legs after lumbar epidural anesthesia % Arndt. Anesthesiology 1985;63:616-23
  • 28. Effect of level of epidural anesthesia on CV responses
    • Volunteers (n=10) received 2% lido LEA (11-20 mg/kg) to produce increasing dermatomal levels of anesthesia
    • Increased arm blood flow (cervical sympathectomy) only when block >T2
    Thoracic dermatome % change from baseline Bonica. Anesthesiology 1970;33:619-26
  • 29. TEA 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. Do either the baricity or the specific the local anesthetic make a difference during spinal anesthesia?
  • 31. Choices in spinal anesthesia
    • Needle size and style
    • Puncture site
    • Local anesthetic species and dose
    • Baricity of local anesthetic solution
    • Patient position after injection
    • Additives (opioids, vasoconstrictors, clonidine, neostigmine)
    • Continuous spinal or combined spinal-epidural
  • 32. Local anesthetic choices for spinal anesthesia
    • Hyperbaric 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 solutions
      • Bupivacaine 0.5% (<3 h)
      • Lidocaine 2% (<2 h)
      • Tetracaine 0.5% (<3 h)
      • Meperidine 2.5% (<2 h)
      • Mepivacaine 1-2%
    • Hypobaric solutions
      • Tetracaine 0.1-0.2% (<3 h)
      • Bupivacaine 0.5% + fentanyl 20 μ g
  • 33. Local anesthetic baricity and spinal anesthesia
    • Hyperbaric solutions
      • Density > CSF
      • Flows to dependent sites
      • Sitting  ”Saddle” block’
      • Supine  thoracic level
    • Isobaric solutions
      • Density  CSF
      • No effect of position
      • Long duration
    • Hypobaric solutions
      • Density < CSF
      • Flows from dependent sites
      • Sitting  ?total spinal
      • Supine  inconsistent spread
      • Jack-knife (Buie)  sacral block
      • Lateral  block of superior side
  • 34. Hyperbaric Isobaric Hypobaric Sensory dermatome 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. Effects of local anesthetic dose on spinal anesthesia
    • Dose of hyperbaric LA has almost no influence on dermatomal spread, even in pregnancy (tetracaine 10 or 15 mg blocks comparable dermatomes)
    •  dose =  onset,  duration, and  &quot;quality&quot; of block (hyperbaric, hypobaric, and isobaric)
  • 36. Combined spinal-epidural (CSE)
    • Rapidly increasing popularity
    • Advantages : rapid onset, ability to titrate or prolong block,  spinal drug dosage
    • Disadvantages : catheter migration,  reliability of test dosing, ↑failure rate (?)
    • Needle through needle vs double segment
    • Useful for :
      • OB analgesia
      • Ambulatory anesthesia
      • Postop pain management after spinal anesthetic
  • 37. Continuous spinal anesthesia
    • Analogous to continuous epidural anesthesia
    • Permits long duration spinal anesthesia
    • No special safety problems provided that there is free flow of CSF through catheter and the catheter tip is not misplaced in a root sleeve
    • Requirement for larger needle  PDPH risk
    • 27g catheters formerly available associated with neurological deficits (maldistribution or restricted distribution of 5% lidocaine?)
  • 38. How case was managed
    • Arterial line placed
    • CSE technique
    • Hyperbaric bupivacaine 5 mg + 20 µg fentanyl
    • Lateral position
    • Phenylephrine drip
    • Patient now in PACU, will you start PCEA infusion with bupivacaine-morphine?
  • 39. How case was managed
    • You have got to be kidding!