Anesthesia and the Cardiac Patient

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Anesthesia and the Cardiac Patient

• Wayne E. Ellis, Ph.D., CRNA

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(No Transcript)
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Preoperative Preparation

• Angina
• Medications to control it
• Blood pressure controlled
• Diastolic lt 95 torr
• Congestive heart failure treated
• Diuretics
• Afterload reduction
• Bedrest if indicated
• Control diabetes

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Preoperative Medications

• Sedation
• Prevent tachycardia
• Hypertension
• Prepared for hypoxia
• Supplemental oxygen
• Calcium channel blockers not protective of
  perioperative ischemia
• Antihypertensives continue on day of surgery
• Stop Diuretics

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Antianginal medications

• Beta-blockers
• Calcium Channel Blockers
• Nitrates
• Nitropaste morning of surgery

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Beta Blockers

• Negative inotropic effects
• Withdrawal following stoppage of beta blocker
• Unstable angina
• Myocardial infarction

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Monitoring

• EKG
• Blood Pressure
• Temperature
• Pulse oximetry
• End tidal CO2

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Arterial Catheter

• Beat to beat blood pressure monitoring
• ABGs
• Early detection of hypotension

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Laboratory studies

• HGB HCT
• Electrolytes
• Liver function studies
• Creatine clearance
• Osmolality

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PA catheter

• Assessment of LV Function
• Early detection of ischemia
• v waves
• Increased PCWP
• More accuracy than CVP
• Intravascular volume problems
• Especially in patients with severe lung disease

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Transesophageal Echocardiography

• Demonstrates regional wall motion abnormalities
• Suggestive of ischemia
• Most accurate measure of left ventricular volume

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Non-invasive Continuous Cardiac Output Monitors

• Transesophageal Doppler
• Thoracic impedance
• Limited
• Accuracy is controversial
• No information about systemic vascular resistance
• Measure CVP

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Improved outcomes

• Aggressive monitoring treatment
• Vasoactive drugs
• Reduced intraoperative ischemia
• MI lt 6 months has better survival rate
• Occurrence reduced from 30-5
• Multi-institution study over last 10 years
• 5000 patients
• Continued for 3 days post-operatively

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Decision to use Invasive Monitoring

• Patients with severe inoperable CAD
• Chronic stable angina undergoing significant
  abdominal or thoracic surgery
• Large blood loss
• History of remote MI with stable angina
• Not necessary to use invasive monitors

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Anesthetic Management

• Regional vs general
• Anesthetic management skills more important than
  technique
• Safest technique is the one the practitioner does
  best

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General anesthesia

• Avoids sympathectomy
• Risks with intubation
• Sympathetic stimulation
• Hypoxia
• Increased catecholamines
• Loss of subjective monitor
• Chest pain
• Ischemia

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General Anesthesia required

• Narcotics
• Effective control of catecholamines
• Respiratory depression
• Prolonged ventilation

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Inductions Agents

• Avoid Ketamine
• Hypertension
• Tachycardia
• Use in trauma
• Etomidate
• Painful to inject
• More CV stability
• Barbiturate
• Direct depressant
• Extended duration of activity
• Smaller doses
• 1-2 mg/kg
• Add benzodiazepines and narcotic

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Benzodiazepines

• Quell anxiety
• Hemodynamic stability
• Extended duration of action
• Potential for hypoxia
• Lidocaine
• Esmolol

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Muscle Relaxants

• Avoid pancuronium
• Tachycardia
• ST segment changes consistent with ischemia
• Doxacurium
• Duration similar to pancuronium
• No cardiovascular effects

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Avoid Histamine releasing drugs

• Curare
• Atracurium
• Mivacurium lt15 mcg/kg
• Hypotension
• Tachycardia

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Inhalation Agents

• Potential for coronary steal
• Alters coronary autoregulation
• Alters regional blood flow
• Little influence on outcome

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Nitrous Oxide

• Constricts coronary arteries
• Aggravates myocardial ischemia
• High FiO2 recommended
• Maintain saturation at 95-100

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Regional Anesthesia

• Monitor patient more accurately
• Control sympathetic responses
• Fluids
• Esmolol

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Intraoperative predictors

• Choice of anesthetic
• Site of surgery
• Duration of Anesthesia
• Emergency Surgery

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Intraoperative predictors

• Choice of Anesthetic
• No difference in infarction rate GETA vs.
  Regional
• No significant hypotension
• No significant tachycardia
• TURP
• Regional decreased risk post MI
• Reinfarction rate
• SAB lt 1
• GETA 2-8

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Intraoperative predictors

• Choice of Anesthetic
• Patient with CHF will benefit from regional
  technique
• Sympathectomy
• Decreased preload
• Coronary Steal
• Potent inhalation agents vs. narcotics

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Intraoperative predictors

• Site of Surgery
• Thoracic and upper abdominal
• 2-3 Xs risk of extremity procedures
• Duration of Anesthetic
• gt 3 hours gt risk of morbidity mortality
• Emergency Surgery
• 2 - 5 Xs greater risk than nonemergent surgery

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Cardioactive drugs

• Nitroglycerin
• Lower LVEDP
• Vasodilator
• Poor ventricular function

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Esmolol

• Control heart rate and blood pressure
• Induction
• Emergence

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Labetalol

• Mixed alpha and beta
• Control hypertension
• Heart rate management

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Lidocaine

• Blunt effects of intubation
• 1.5 mg/kg 4-6 minutes prior to intubation

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Clonidine

• Less hypertension
• Decreased anesthesia requirements

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Nifedipine

• Controlling hypertension
• Manage coronary artery spasm

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Postoperative Management

• Maintain analgesia
• Balance supply and demand
• Supplemental oxygen
• Continue monitoring into postoperative period
• Early transfusion

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Coronary Artery Disease

• Major Goal
• Balance Supply and Demand
• Primary Determinants of Myocardial Oxygen Demand
• Wall tension and Contractility

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Coronary Artery Disease

• Factors modifying coronary blood flow
• diastolic time
• perfusion pressure
• coronary vascular tone
• intraluminal obstruction

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Coronary Artery Disease

• Myocardial O2 Extraction
• infrequently the cause of ischemia
  intraoperatively
• Arterial O2 Content
• Correction of anemia
• High FiO2

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Hemodynamic Goals for the Patient with CAD

• P - keep the heart small, decrease wall
  tension, increase perfusion pressure
• A - maintain, hypertension better than
  hypotension
• C - depression is beneficial when LV function is
  adequate
• R - slow, slow, slow

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Hemodynamic Goals for the patient with CAD

• Rhythm - usually sinus
• MVO2 - control of demand frequently not enough,
  monitor for and treat supply ischemia
• CPB - elevated ventricular filling pressure
  usually not needed after CABG

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Valvular Heart Disease

• Aortic Stenosis
• IHSS
• Aortic Insufficiency

• Mitral Stenosis
• Mitral regurgitation

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Aortic Stenosis

• Characterized by
• Obstruction to LV outflow
• Intraventricular systolic pressure and wall
  tension increase
• Concentric hypertrophy
• Decreased LV compliance
• Reliance on atrial contribution

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Hemodynamic Goals for the Patient with AS

• P - full, adequate intravascular volume to fill
  noncompliant ventricle
• A - already elevated but relatively fixed,
  coronary perfusion pressure must be maintained
• C - usually not a problem, inotropes may be
  helpful preinduction in end-stage AS with
  hypotension

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Hemodynamic Goals for the Patient with AS

• R - not too slow (decrease CO), not too fast
  (ischemia)
• Rhythm - Sinus!! Cardioversion if hemodynamic
  instability from SV dysrhythmias
• MVO2 - Ischemia is an ever present risk, Avoid
  tachycardia and hypotension

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Idiopathic Hypertrophic Subaortic Stenosis

• Characterized by
• Myocardial hypertrophy
• 20 -30 have subvalvular obstruction
• Outflow tract of LV is narrowed
• Increases in contractility, heart rate or
  decreases in preload or afterload increase the
  risk of ischemia

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Hemodynamic Goals for the Patient with IHSS

• P - Full, full, full volume is treatment for
  hypotension
• A - Up, up, up vasoconstrictor follows fluid for
  hypotension
• C - Depression is ok
• R - not too slow, not too fast

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Hemodynamic Goals for the Patient with IHSS

• Rhy - Sinus, sinus, sinus consider pacing PA
  cath to control atrial mechanism
• MVO2 - Usual precautions apply
• CPB - Avoid inotropes post-CPB, the myocardial
  disease is still present, try vasoconstrictors
  first

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Aortic Insufficiency

• Characterized by
• Chronic volume overload
• Ventricular dilatation
• Eccentric hypertrophy
• Forward stroke volume higher than normal causing
  increased systolic pressure
• Regurgitation across the valve causes diastolic
  pressure to be lower than normal

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Hemodynamic Goals for the Patient with AI

• P - normal to slightly increased
• A - Reduction beneficial with anesthetics or
  vasodilators,increases augment regurgitant flow
• C - usually adequate
• R - Modest tachycardia reduces ventricular
  volume, raises aortic diastolic pressure

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Hemodynamic Goals for the Patient with AI

• Rhythm - usually sinus, not a problem
• MVO2 - Not usually a problem
• CPB - observe for ventricular distention
  (decreased HR, increased ventricular filling
  pressure) when going onto bypass

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Mitral Stenosis

• Characterized by
• Normal ventricular function
• Obstruction to left atrial emptying decreases
  cardiac output
• Pulmonary congestion from elevations in LA and
  pulmonary venous pressure
• Pulmonary hypertension and RVH over time

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Hemodynamic Goals for the Patient with MS

• P - Enough to maintain flow across stenotic valve
• A - Avoid increased RV afterload
• C - LV usually ok until after CPB, with
  longstanding PHTN RV may be impaired
• R - slow to allow time for ventricular filling

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Hemodynamic Goals for the Patient with MS

• Rhythm - Often atrial fibrillation, control
  ventricular response
• MVO2 - Not a problem
• CPB - Vasodilators may help post-CPB RV failure,
  control of ventricular response may be difficult

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Mitral Regurgitation

• Characterized by
• Chronic volume overload similar to AI
• Increased ventricular compliance without change
  in LVEDP
• May mask signs of impaired ventricular function

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Hemodynamic Goals for the Patient with MI

• P - Usually pretty full, may need to keep that
  way, although preload reduction may reduce
  regurgitant flow
• A - Decreases are beneficial, increases augment
  regurgitant flow
• C - Unrecognized myocardial depression possible,
  titrate myocardial depressants carefully

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Hemodynamic Goals for the Patient with MI

• R - A faster rate decreases ventricular volume
• Rhythm - Atrial fibrillation is occasionally a
  problem
• MVO2 - only if associated with CAD, then caution!
• CPB - New valve will increase afterload,
  unmasking impaired ventricle

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Anesthetic Technique

• Goals of Anesthesia
• loss of conciousness
• amnesia
• analgesia
• suppression of reflexes (endocrine and autonomic)
• muscle relaxation

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Inhalation Agents

• Advantages
• Myocardial oxygen balance altered favorably by
  reductions in contractility and afterload
• Easily titratable
• Can be administered via CPB machine
• Rapidly eliminated

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Inhalation Agents

• Disadvantages
• Significant hemodynamic variability
• May cause tachycardia or alter sinus node
  function
• Possibility of coronary steal syndrome

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Coronary Steal

• Arteriolar dilation of normal vessels diverts
  blood away from stenotic areas
• Commonly associated with adenosine, dipyridamole,
  and SNP
• Forane causes steal and new ST-T segment
  depression
• May not be important since Forane reduces SVR,
  depresses the myocardium yet maintains CO

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Opioids

• Advantages
• Excellent analgesia
• Hemodynamic stability
• Blunt reflexes
• Can use 100 oxygen

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Opioids

• Disadvantages
• May not block hemodynamic and hormonal responses
  in patients with good LV function
• Do not ensure amnesia
• Chest wall rigidity
• Respiratory depression

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Induction Drugs

• Barbiturates
• Benzodiazepines
• Ketamine
• Etomidate

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Nitrous Oxide

• Rarely used due to
• increased PVR
• depression of myocardial contractility
• mild increase in SVR
• air expansion

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Muscle Relaxants

• Used to
• facilitate intubation
• prevent shivering
• attenuate skeletal muscle contraction during
  defibrillation

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Postoperative predictors

• Ischemia does occur most commonly in the
  postoperative period
• Persists for 48 hours or longer following
  non-cardiac surgery
• Predictor value is unknown
• Goldman, L., (1983) Cardiac Risk and
  Complications of noncardiac surgery, Annals of
  Internal Medicine. 98504-513

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Medications

• Beta Blockers
• CEB
• Nitrates
• Lidocaine
• Procainamide
• ACE Inhibitors
• MAO Inhibitors
• Psychotropic Medications
• Alternative and supplemental additives

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Affects Oxygen Supply

• Coronary blood flow
• Perfusion
• Atria and normal RV during entire cycle
• Left ventricle during diastole
• With increased heart rate diastole is shortened
• Coronary perfusion pressure (LV)
• Diastolic pressure minus left ventricular end
  diastolic pressure
• CPP DP - LVEDP

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Heart Rate

• The faster the rate the more oxygen required
• The faster the rate there is less time for tissue
  oxygenation
• Many studies have focused on the best anesthesia
  technique for the cardiac patient
• Gonzales, University of Iowa
• The best technique in the hands of the
  practitioner with an adequate knowledge of
  physiology, pathophysiology, pharmacology and
  patient dynamics

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Beta-blockers

• Reduce perioperative ischemia in those undergoing
  noncardiac surgery
• Known coronary artery disease
• High risk of coronary artery disease (2 or more
  risk factors)
• Atenolol
• Started preoperatively and continued until
  discharge from the hospital
• May decrease overall mortality at 2 years
• Most of the lower mortality is attributable to
  lower cardiac mortality in the 6 to 8 months
  after surgery
• Bisoprolol with similar results
• References
• New England Journal of Medicine 3351713-1720,
  1996
• Anesthesiology 17-17, 1998
• New England Journal of Medicine 3411789-94,
  1999.

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Oxygen Supply

• With coronary stenosis
• Improve CPP
• Increase systemic pressure
• Lower elevated LVEDP
• Nitroglycerin
• Hemoglobin Level
• Oxygen saturation

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Temperature

• Keep warm
• Decreasing temperature
• Shift Oxygen dissociation curve to left
• Hemoglobin retains oxygen at tissue level
• Prevent alkalosis

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Preoperative considerations

• Medications
• Pacemaker
• Does Patient have one?
• Does Patient need one?
• Defibrillator

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Monitoring

• Enough ECGs already
• Invasive monitors
• Radial arterial catheter
• CVP
• PA
• TEE
• Transesophageal echocardiography

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Anesthesia

• Goal
• Does technique make a difference?
• Laryngoscopy
• Maintenance
• Regional anesthesia

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Treatment of ischemia

• Is it real?
• Optimize oxygenation and hemodynamics
• IV NTG
• SL Nifedipine
• Diltiazem
• Intra-aortic Ballon Pump
• Improves systolic run off
• Provides diastolic augmentation

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IABP
Systole
Coronary arteries
Diastole
Aortic valve
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IABP
Systole
Systole Balloon deflates
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IABP
Diastole
Systole
Diastole Balloon inflates
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IABP
Systole
Systole Balloon deflates