Noncardiovascular Surgery for the Cardiac Patient

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Noncardiovascular Surgery for the Cardiac Patient

• Wayne E. Ellis, Ph.D., CRNA

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Statistics

• 30 million noncardiac surgeries annually
• 3 million individuals with known or probable
  Coronary Artery Disease
• 50,000 (1.7) Perioperative MIs annually
• 10,000 - 20,000 deaths per year
• (20 - 40 mortality)
• 25 - 50 of all perioperative deaths annually
• Costs gt 500 million per year

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Preoperative Assessment

• History
• Physical exam
• Laboratory findings and other tests

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History - Do a good one!!!

• Stability of angina
• NYHA
• Class I Mild angina without impairment
• Class IV Angina at rest
• Exercise tolerance!
• Ventricular function
• Associated cardiovascular diseases
• Medication

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Recent Myocardial Infarction

• Less than three months
• Patient lt 70 years of age
• Location of surgery
• Duration of surgery
• Poor LV function
• CHF
• Enlarged heart
• Arrhythmias
• Increased risk of morbidity and MORTALITY

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Perioperative Predictors

• Recent MI
• lt 6 months
• Current CHF
• Only consistent predictors of perioperative
  outcome

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Prior MI

• of patients having a reinfarction compared to
  the time from MI to operation
• Tarhan et al, 1972
• 3 mon 37
• 3-6 mon 16
• gt6 mon 5.6

Risk factors for reinfarction
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Prior MI

• of patients having a reinfarction compared to
  the time from MI to operation
• Steen et al, 1978
• 3 mon 27
• 3-6 mon 11
• gt6 mon 6

Risk factors for reinfarction
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Prior MI

• of patients having a reinfarction compared to
  the time from MI to operation
• Rao et al, 1978
• 3 mon 5.7
• 3-6 mon 2.3
• gt6 mon 1.5

Risk factors for reinfarction
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Prior MI

• of patients having a reinfarction compared to
  the time from MI to operation
• Shah et al, 1990
• 3 mon 4.3
• 3-6 mon 4.3
• gt6 mon 5.7
• Age undeterminate 3.3

Risk factors for reinfarction
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Prior MI

• Mortality due to reinfarction about 30
• Historically cited as 50

Risk factors for reinfarction
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Prior MI

• The differences between the studies
• Monitoring
• ICU stay
• Can apply these interventions to all of your
  patients?

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Challenge of anesthesia

• Adequately evaluate the patient
• Provide adequate anesthesia
• Prevent myocardial injury
• Maximize postoperative pain management

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RISK FACTORS

• genetic predisposition
• age
• gender
• obesity
• hyperlipedemia
• diabetes mellitus
• hypertension
• stress, tobacco, and smoking

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Smoking

• Increases the risk of an initial cardiac event
  and doubles the rate of subsequent infarction and
  death.
• Risk rapidly declines after stopping and by 3
  years reaches that of survivors who have never
  smoked.

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Assessment of risk factors

• Cigarette smoking
• Hypertension
• Diabetes
• Family history
• May have a normal physical

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Perioperative estimation of cardiac risk

• Recent preoperative MI
• average 8 reinfarction if within 3 months
• Optimal preparation
• Invasive Monitoring
• Without monitoring
• gt 30
• Age
• gt 70
• 10 fold increased risk

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Coronary Artery Disease

• Most common cause of premature death for males
  between 35-45years of age.
• Each year 1.5 million MIs occur in the U.S.
• 280,000 OHS every year in the U.S.
• 60 billion spent annually to treat CAD
• OHS represents 80 of the total adult operations
  performed at most medical centers in the U.S.

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Atheroscelerosis

• begins as crystals of cholesterol adheres to the
  intima.
• These crystals then form a larger matrix that
  stimulates surrounding fibrous and smooth muscle
  tissue growth to create additional layers i.e.)
  larger plaques can grow

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Atheroscelerosis

• Larger plaques then develop into total
  obstructive lesions, resulting in
  sclerosis(fibrosis)
• Atherosclerosis lesions become symptomatic with
  75 stenosis of one or more coronary vessels
  ischemia, which depresses the myocardial
  function, causes chest pain (angina pectoris).

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CAD

• Modulated by 3 factors
• 1) Myocardial oxygen demand
• 2) Myocardial oxygen supply
• 3) Coronary blood flow

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Myocardial Oxygen Demand (MvO2)

• Heart extracts more 02 than any other organ,
  50-70 at rest
• BP and HR provides a basic guideline for Mv02
• contractility and myocardial wall tension are
  primary determinants of Mv02
• wall tension can be lowered by decreasing preload
• contractility can be lowered by beta blockers or
  pain management relief

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Determinants of Oxygen Supply

• Degree of muscular contractility
• Frank Startling Principle
• The more stretch placed on a muscle fiber before
  contraction, the more forceful the contraction.
• Ventricular preload

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Wall tension of the left ventricle

• Afterload
• With increased resistance
• Hypertrophy
• Increased muscle mass
• Maintain normal wall tension

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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

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Myocardial Oxygen Supply

• Any increase in myocardial oxygen requirements
  can be met only by raising coronary blood flow
• Maintaing the bloods oxygen carrying capacity is
  the secondary objective for cardiovascular
  perfusion

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Myocardial Oxygen Supply

• Oxygen content Ca02
• CaO2 (hgb x 1.34) x Sa02 (Pa02 x 0.0003)
• 1.34 milliliters of 02 per gm of hgb
• Sa02 of oxyhemoglobin of total
  hemoglobin(fractional saturation)
• 0.003 oxygen solubility in plasma

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Influences affecting oxygen supply

• Coronary blood flow
• Left ventricle during diastole
• With increased heart rate diastole is shortened
• Coronary perfusion pressure
• Diastolic pressure minus left ventricular end
  diastolic pressure
• CPP DP-LVEDP

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Oxygen Supply

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

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Myocardial Oxygen Supply

• Any increase in myocardial oxygen requirements
  can be met only by raising coronary blood flow
• Maintaing the bloods oxygen carrying capacity is
  the secondary objective for cardiovascular
  perfusion

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Coronary blood flow

• Perfusion of the left ventricle takes place
  almost entirely during diastole, whereas the
  right ventricle occurs mostly with systole.
• Not only is diastole important, but the length of
  diastole is critical in determining the volume of
  left ventricular subendocardial flow

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Coronary blood flow

• Coronary perfusion psi aortic diastolic
  pressure(AoDp) - LVEDP
• Note hypotension is more likely to produce
  ischemia than hypertension

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Temperature

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

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Evaluation

• Select patients at highest risk of difficulty
• Reinfarction in 1st 6 months post MI high
• High fatality rate
• CABG or Angioplasty first
• Choice of monitoring

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Physical exam Not a lot here

• Vital signs
• Cardiac exam
• PMI
• Gallops
• S4 HTN, S3 increased LVEDP
• Apical systolic murmur
• Papillary muscle dysfunction
• Precordial bulge
• Other signs of LV function
• JVD, pulmonary signs

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Physical Examination

• Cardiovascular
• JVD
• Carotid Bruits
• Murmurs
• S3, S4, Click, Rub
• Pitting Edema
• Pulses
• Vascular Access

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Physical Examination

• Pulmonary
• Wheezes
• Rales
• Rhonchi
• A-P Diameter

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Diagnostic Studies

• ECG
• ischemia
• infarction
• dysrhythmias
• heart block
• conduction abnormalities

• CXR
• cardiomegaly
• pulmonary vascular congestion
• pulmonary edema
• pleural effusion

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ECG

• How many msec after the J point??
• How many mm??
• A resting 12 lead is not a whole lot of good for
  detecting ischemia

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Chest X-Ray

• Cardiomegaly
• Signs of ventricular dysfunction
• Edema, effusions
• Complicating diseases
• Calcification of vessels, valves
• Pulmonary disease

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Blood tests

• CK, other cardiac enzymes
• R/O after surgery Usually an MB of about 5-7 of
  total CK
• Triponin gt7 positive
• Associated diseases
• Diabetes, thyroid disease

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Diagnostic Studies

• Cardiac Catheterization
• Two types of information
• Hemodynamic parameters
• Visualization of vessels, wall motion

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Primary Treatment

• Antiplatelet agents(abciximab,eptifibatide,
  tirofiban, integullin)
• GPIIb-IIIa antagonists
• inhibit platelet function by blocking the
  GPIIb-IIIa receptor, the final pathway of
  platelet aggregation
• thereby decreasing thrombi development and
  prevents arterial vessel occlusion

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Percutaneous Coronary Intervention

• Advantages include higher recanulazation rates
• improved blood flow through the infarct-related
  vessel
• improved LV function
• lower in-hospital mortality rates

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Normal Hemodynamic Measurements

• RA (mean)
• RV (mean)
• PA (sys/dys)
• LA or wedge (mean)
• LV (sys/dys)
• Systemic arterial (sys/dys)

• 2 - 8
• 15 - 30/2 - 8
• 15 - 30/4 - 12
• 2 - 10
• 100 - 140/3 - 12
• 100 - 140/60 - 90

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Monitoring

• Routine
• Pulse Oximetry
• PNS
• Capnography
• Temperature
• Core and peripheral
• ECG
• Leads V5 and II

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Monitors of Cardiac Performance

• Arterial Line
• Standard of Care
• Site selection
• Pulmonary Artery Catheter
• Provides means for assessing filling pressures
• Reliable site for drug administration
• Transesophageal Echocardiography

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Evaluation of the heart

• The pump
• Ventricular function
• The fuel supply
• Degree of coronary artery disease

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Ventricular Function

• History
• Periods of CHF
• Diuretics
• Sleep patterns
• Sleeping position
• Wakes up at night
• Night sweats
• Chest pain at rest

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Physical signs

• Jugular distention
• Chest sounds
• Rales
• Extra heart sounds

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Echocardiography

• Assess ejection fraction
• Wall motion abnormalities
• Valvular function

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MUGA

• Multiple uptake Gated Acquisition Scan
• Accurate estimate of ejection fraction

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EKG

• Is it necessary for evaluation?
• Compare to previous EKG
• If none present
• Establish base line
• May be normal

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Exercise Tolerance Test

• Inadequate exercise is non-diagnostic test
• Not a negative test
• Unable to exercise
• Thallium Scan
• Thallium - Persantine Scan
• Dobutamine assisted scan

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Cardiac Catheterization

• Gold standard
• Determine degree of large vessel disease
• Not predictor of small vessel disease
• Done prior to CABG or Angioplasty
• Not necessary before routine surgery??

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Patients requiring CABG or Angioplasty

• Stenosis of LAD lt 50
• Severe three vessel dysfunction
• Severe two vessel disease with poor LV function

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Preoperative Evaluation

• History
• Physical assessment
• EKG evaluation
• Exercise tolerance
• Chest X-ray
• Lab studies

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Preoperative Evaluation

• Current Medication
• Beta-blockers
• Calcium Channel Blockers
• Antidysrhythmia agents
• Nitrates
• Diuretics
• Antihypertensive agents

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Dyspnea

• Activity
• Rest
• What starts it
• How long lasts

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Perioperative Predictors

• Angina
• Associated with angiographically significant CAD
• gt 70 stenosis
• At Risk for significant CAD
• 90 of males gt 40
• 90 of females gt 60
• Stable angina Conspicuously insignificant
  predictor (Goldman)

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History of anginal pattern

• Stable
• No recent change
• Medications
• Exercise tolerance
• Frequency
• Require little to no additional work-up

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History of Anginal Pattern

• Unstable
• Change in occurrence or type of pain
• Requires further evaluation
• Myocardial Infarction
• When

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Perioperative Predictors

• Congestive Heart Failure
• LV Failure
• Poor prognosis
• Patient with CAD
• One of most important predictors of short and
  long term cardiac mortality
• Signs with predictive value
• Third heart sound
• Jugular venous distention

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Perioperative Predictors

• Preoperative Ejection Fraction lt 40
• Predictive of
• Perioperative MI
• Reinfarction
• Perioperative ventricular dysfunction
• Ejection Fraction lt 30
• 1 year cumulative mortality gt 30

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Perioperative Predictors

• Hypertension
• Risk Factor for
• Ischemic heart disease
• CHF
• Stroke
• Ability to predict is controversial
• Diastolic pressure gt 110 significant cardiac risk

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Perioperative Predictors

• Diabetes Mellitus
• Increased risk for CAD
• Cardiomyopathy
• Abnormal autonomic function/tone
• 20-40 of diabetics
• Increased intraoperative risk of
• Ischemia
• Infarction

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Perioperative Predictors

• Dysrhythmias
• Frequent PVCs or PACs
• Independent predictor
• Intraoperative difficulty
• PVCs most frequent indicator of postoperative
  morbidity mortality

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Perioperative Predictors

• Peripheral Vascular Disease
• High risk of Perioperative Cardiac Mortality
• Vascular Surgery gt 15 risk of MI
• Non-vascular surgery unknown

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Perioperative Predictors

• Valvular Heart Disease
• Aortic Stenosis
• Increased perioperative mortality
• Underlying heart failure
• Difficulties in perioperative fluid management
• Other valvular disorders
• Predictors uncertain

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Perioperative Predictors

• Cholesterol
• Risk unknown
• Smoking
• Not a predictor of adverse cardiac outcomes
• Previous CABG
• Protection against development of perioperative
  cardiac morbidity
• Previous angioplasty
• No accurate data

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Perioperative Predictors

• Cardiovascular Therapy
• Beneficial effects
• Nitrates
• Beta Blocking Agents
• Calcium entry blocking agents
• Preoperative withdrawal yields higher incidence
  of perioperative ischemia, dysrhythmia, MI and
  cardiac death
• Intraoperative prophylaxis - Undetermined

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Dynamic Predictors

• Acute imbalances in myocardial oxygen supply and
  demand may produce ischemia that may result in
  irreversible cardiac morbidity
• Hypertension
• Hypotension
• Tachycardia

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Dynamic Predictors

• Hypertension
• No conclusive correlation
• Intraoperative Hypertension
• MI
• Acute Hypertension
• Precedes intraoperative ischemic events
• 50 of time

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Dynamic Predictors

• Hypotension
• 25 of ischemic events associated with gt 20
  decrease in systolic blood pressure
• 6 decrease in MAP
• Important predictor of PCM
• Higher reinfarction rate
• 15.2 vs. 3.2
• Intraoperative hypotension
• gt 30 decrease in systolic BP
• gt 10 minutes duration

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Dynamic Predictors

• Tachycardia
• Combination with hypotension
• Ominous
• Significant indicator of PCM
• Myocardial Ischemia
• ST changes
• Not a clear indicator of PCM
• TEE
• Most sensitive, earlier indices of ischemia
• Before ST segment changes

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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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Anesthesia Goals

• Balance supply and demand
• Control heart rate
• Normal to slow range
• Maintain CPP
• Prevent hypotension
• Prevent increased LVEDP
• Optimize arterial oxygen and carbon dioxide
  status
• Keep patient normothermic
• Higher threshold for transfusion

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Anesthesia

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

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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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Noninvasive beat to beat analysis

• Finapress
• Ohmeda

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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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Avoid Ketamine

• Hypertension
• Tachycardia
• Use in trauma

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Etomidate

• Painful to inject
• More CV stability

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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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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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