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Noncardiovascular Surgery for the Noncardiovascular Surgery for the Cardiac PatientCardiac Patient
Wayne E. Ellis, Ph.D., CRNAWayne E. Ellis, Ph.D., CRNA
04/11/23 WE Ellis 4
Preoperative Assessment
• History• Physical exam• Laboratory findings and other
tests
04/11/23 WE Ellis 5
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 InfarctionRecent Myocardial Infarction
Less than three monthsLess than three monthsPatient < 70 years of agePatient < 70 years of ageLocation of surgeryLocation of surgeryDuration of surgeryDuration of surgeryPoor LV functionPoor LV function
CHFCHFEnlarged heartEnlarged heartArrhythmiasArrhythmias
Increased risk of morbidity and MORTALITYIncreased risk of morbidity and MORTALITY
04/11/23 WE Ellis 7
Perioperative PredictorsPerioperative Predictors
Recent MIRecent MI< 6 months< 6 monthsCurrent CHFCurrent CHF
Only consistent predictors of Only consistent predictors of perioperative outcomeperioperative outcome
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Challenge of anesthesiaChallenge of anesthesia
Adequately evaluate the patientAdequately evaluate the patientProvide adequate anesthesiaProvide adequate anesthesiaPrevent myocardial injuryPrevent myocardial injuryMaximize postoperative pain Maximize postoperative pain
managementmanagement
04/11/23
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 factorsAssessment of risk factors
Cigarette smokingCigarette smokingHypertensionHypertensionDiabetesDiabetesFamily historyFamily historyMay have a normal physicalMay have a normal physical
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Perioperative estimation of cardiac riskPerioperative estimation of cardiac risk
Recent preoperative MIRecent preoperative MIaverage 8% reinfarction if within 3 monthsaverage 8% reinfarction if within 3 months
Optimal preparationOptimal preparationInvasive MonitoringInvasive Monitoring
Without monitoringWithout monitoring> 30%> 30%
AgeAge> 70> 70
10 fold increased risk10 fold increased risk
04/11/23
Coronary Artery Disease
• Most common cause of premature death for males between 35-45years of age.
• Each year 1.5 million MI’s 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.
04/11/23
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).
04/11/23
CAD
• Modulated by 3 factors– 1) Myocardial oxygen demand– 2) Myocardial oxygen supply– 3) Coronary blood flow
04/11/23
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
04/11/23 WE Ellis 24
Determinants of Oxygen SupplyDeterminants of Oxygen Supply
Degree of muscular contractilityDegree of muscular contractilityFrank Startling PrincipleFrank Startling PrincipleThe more stretch placed on a muscle fiber The more stretch placed on a muscle fiber
before contraction, the more forceful the before contraction, the more forceful the contraction.contraction.
Ventricular preloadVentricular preload
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Wall tension of the left ventricleWall tension of the left ventricle
AfterloadAfterloadWith increased resistanceWith increased resistance
HypertrophyHypertrophyIncreased muscle massIncreased muscle mass
Maintain normal wall tensionMaintain normal wall tension
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Heart rateHeart rate
The faster the rate the more oxygen requiredThe faster the rate the more oxygen requiredThe faster the rate there is less time for tissue The faster the rate there is less time for tissue
oxygenationoxygenation
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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
04/11/23 WE Ellis 29
Influences affecting oxygen supplyInfluences affecting oxygen supplyCoronary blood flowCoronary blood flowLeft ventricle during diastoleLeft ventricle during diastoleWith increased heart rate diastole is shortenedWith increased heart rate diastole is shortenedCoronary perfusion pressureCoronary perfusion pressure
Diastolic pressure minus left ventricular end Diastolic pressure minus left ventricular end diastolic pressurediastolic pressure
CPP = DP-LVEDPCPP = DP-LVEDP
04/11/23 WE Ellis 30
Oxygen SupplyOxygen SupplyWith coronary stenosisWith coronary stenosis
Improve CPPImprove CPPIncrease systemic pressureIncrease systemic pressureLower elevated LVEDPLower elevated LVEDP
NitroglycerinNitroglycerinHgb LevelHgb LevelOxygen saturationOxygen 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
04/11/23
Coronary blood flow
• Coronary perfusion psi = aortic diastolic pressure(AoDp) - LVEDP
• Note hypotension is more likely to produce ischemia than hypertension
04/11/23 WE Ellis 34
TemperatureTemperature
Keep warmKeep warmDecreasing temperatureDecreasing temperature
Shift Oxygen dissociation curve to leftShift Oxygen dissociation curve to leftHgb retains oxygen at tissue levelHgb retains oxygen at tissue level
Prevent alkalosisPrevent alkalosis
04/11/23 WE Ellis 35
EvaluationEvaluationSelect patients at highest risk of difficultySelect patients at highest risk of difficultyReinfarction in 1st 6 months post MI highReinfarction in 1st 6 months post MI highHigh fatality rateHigh fatality rateCABG or Angioplasty firstCABG or Angioplasty firstChoice of monitoring Choice of monitoring
04/11/23 WE Ellis 36
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
04/11/23 WE Ellis 37
Physical ExaminationPhysical Examination
CardiovascularCardiovascularJVDJVDCarotid BruitsCarotid BruitsMurmursMurmursS3, S4, Click, RubS3, S4, Click, RubPitting EdemaPitting EdemaPulsesPulsesVascular AccessVascular Access
04/11/23 WE Ellis 38
Physical ExaminationPhysical Examination
PulmonaryPulmonaryWheezesWheezesRalesRalesRhonchiRhonchiA-P DiameterA-P Diameter
04/11/23
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
04/11/23
Chest X-Ray• Cardiomegaly• Signs of ventricular dysfunction– Edema, effusions
• Complicating diseases– Calcification of vessels, valves– Pulmonary disease
04/11/23
Blood tests
• CK, other cardiac enzymes– R/O after surgery: Usually an MB of about 5-
7% of total CK
• Triponin >7 positive
• Associated diseases–Diabetes, thyroid disease
04/11/23
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
04/11/23
Percutaneous Coronary Intervention
• Advantages include: higher recanulazation rates
• improved blood flow through the infarct-related vessel
• improved LV function• lower in-hospital mortality rates
04/11/23 WE Ellis 46
Normal Hemodynamic MeasurementsNormal Hemodynamic Measurements
RA (mean)RA (mean)RV (mean)RV (mean)PA (sys/dys)PA (sys/dys)LA or wedge (mean)LA or wedge (mean)LV (sys/dys)LV (sys/dys)Systemic arterial Systemic arterial
(sys/dys)(sys/dys)
2 - 82 - 815 - 30/2 - 815 - 30/2 - 815 - 30/4 - 1215 - 30/4 - 122 - 102 - 10100 - 140/3 - 12100 - 140/3 - 12100 - 140/60 - 90100 - 140/60 - 90
04/11/23 WE Ellis 47
MonitoringMonitoring
RoutineRoutinePulse OximetryPulse OximetryPNSPNSCapnographyCapnographyTemperatureTemperature
Core and peripheralCore and peripheral
ECGECGLeads V5 and IILeads V5 and II
04/11/23 WE Ellis 48
Monitors of Cardiac PerformanceMonitors of Cardiac Performance
Arterial LineArterial LineStandard of CareStandard of CareSite selectionSite selection
Pulmonary Artery CatheterPulmonary Artery CatheterProvides means for assessing filling pressuresProvides means for assessing filling pressuresReliable site for drug administrationReliable site for drug administration
Transesophageal EchocardiographyTransesophageal Echocardiography
04/11/23 WE Ellis 51
Physical signsPhysical signsJugular distentionJugular distentionChest soundsChest sounds
RalesRalesExtra heart soundsExtra heart sounds
04/11/23 WE Ellis 58
Preoperative EvaluationPreoperative EvaluationHistoryHistoryPhysical assessmentPhysical assessmentEKG evaluationEKG evaluationExercise toleranceExercise toleranceChest X-rayChest X-rayLab studiesLab studies
04/11/23 WE Ellis 59
Preoperative EvaluationPreoperative Evaluation
Current MedicationCurrent MedicationBeta-blockersBeta-blockersCalcium Channel BlockersCalcium Channel BlockersAntidysrhythmia agentsAntidysrhythmia agentsNitratesNitratesDiureticsDiureticsAntihypertensive agentsAntihypertensive agents
04/11/23 WE Ellis 60
DyspneaDyspnea
ActivityActivityRestRestWhat starts itWhat starts itHow long lastsHow long lasts
04/11/23 WE Ellis 73
Dynamic PredictorsDynamic Predictors
Acute imbalances in myocardial oxygen supply and Acute imbalances in myocardial oxygen supply and demand may produce ischemia that may result in demand may produce ischemia that may result in irreversible cardiac morbidityirreversible cardiac morbidity
HypertensionHypertensionHypotensionHypotensionTachycardiaTachycardia
04/11/23 WE Ellis 74
Dynamic PredictorsDynamic Predictors
HypertensionHypertensionNo conclusive correlation No conclusive correlation
Intraoperative HypertensionIntraoperative HypertensionMIMI
Acute HypertensionAcute HypertensionPrecedes intraoperative ischemic eventsPrecedes intraoperative ischemic events50% of time50% of time
04/11/23 WE Ellis 75
Dynamic PredictorsDynamic Predictors
HypotensionHypotension25 % of ischemic events associated with 25 % of ischemic events associated with >> 20 % decrease in 20 % decrease in
systolic blood pressuresystolic blood pressure6 % decrease in MAP6 % decrease in MAPImportant predictor of PCMImportant predictor of PCM
Higher reinfarction rateHigher reinfarction rate15.2 % vs. 3.2 %15.2 % vs. 3.2 %Intraoperative hypotensionIntraoperative hypotension
>> 30% decrease in systolic BP 30% decrease in systolic BP>> 10 minutes duration 10 minutes duration
04/11/23 WE Ellis 76
Dynamic PredictorsDynamic Predictors
TachycardiaTachycardiaCombination with hypotensionCombination with hypotensionOminousOminousSignificant indicator of PCMSignificant indicator of PCM
Myocardial IschemiaMyocardial IschemiaST changesST changes
Not a clear indicator of PCMNot a clear indicator of PCM
TEETEEMost sensitive, earlier indices of ischemiaMost sensitive, earlier indices of ischemiaBefore ST segment changesBefore ST segment changes
04/11/23
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
04/11/23 WE Ellis 78
Anesthesia GoalsAnesthesia Goals
Balance supply and demandBalance supply and demandControl heart rateControl heart rate
Normal to slow rangeNormal to slow rangeMaintain CPPMaintain CPP
Prevent hypotensionPrevent hypotensionPrevent increased LVEDPPrevent increased LVEDP
Optimize arterial oxygen and carbon dioxide Optimize arterial oxygen and carbon dioxide statusstatus
Keep patient normothermicKeep patient normothermicHigher threshold for transfusionHigher threshold for transfusion
04/11/23
Anesthesia
• Goal• Does technique make a difference?• Laryngoscopy• Maintenance• Regional anesthesia
Preoperative Preparation
AnginaMedications to control it
Blood pressure controlledDiastolic < 95 torr
Congestive heart failure treatedDiureticsAfterload reductionBedrest if indicated
Control diabetes
Preoperative Medications
SedationPrevent tachycardiaHypertension
Prepared for hypoxiaSupplemental oxygen
Calcium channel blockers not protective of perioperative ischemia
Antihypertensives continue on day of surgeryStop Diuretics
04/11/23 WE Ellis 82
Antianginal medications
Beta-blockersCalcium Channel BlockersNitratesNitropaste morning of surgery
Beta Blockers
Negative inotropic effectsWithdrawal following stoppage of beta
blockerUnstable anginaMyocardial infarction
Monitoring
EKGBlood PressureTemperaturePulse oximetryEnd tidal CO2
Arterial Catheter
Beat to beat blood pressure monitoringABGs Early detection of hypotension
Laboratory studies
HGB & HCTElectrolytesLiver function studiesCreatine clearanceOsmolality
Noninvasive beat to beat analysis
FinapressOhmeda
PA catheterAssessment of LV FunctionEarly detection of ischemia
“v” wavesIncreased PCWP
More accuracy than CVPIntravascular volume problemsEspecially in patients with severe lung disease
Transesophageal Echocardiography
Demonstrates regional wall motion abnormalities
Suggestive of ischemiaMost accurate measure of left ventricular
volume
Non-invasive Continuous Cardiac Output Monitors
Transesophageal DopplerThoracic impedanceLimitedAccuracy is controversialNo information about systemic
vascular resistanceMeasure CVP
Improved outcomes
Aggressive monitoring & treatmentVasoactive drugsReduced intraoperative ischemia
MI < 6 months has better survival rateOccurrence reduced from 30-5%Multi-institution study over last 10 years5000 patientsContinued for 3 days post-operatively
Decision to use Invasive Monitoring
Patients with severe inoperable CADChronic stable angina undergoing significant
abdominal or thoracic surgeryLarge blood lossHistory of remote MI with stable angina
Not necessary to use invasive monitors
Anesthetic Management
Regional vs generalAnesthetic management skills more
important than techniqueSafest technique is the one the practitioner
does best
General anesthesia
Avoids sympathectomyRisks with intubation
Sympathetic stimulationHypoxiaIncreased catecholamines
Loss of subjective monitorChest painIschemia
General Anesthesia required
NarcoticsEffective control of catecholaminesRespiratory depressionProlonged ventilation
Avoid Ketamine
HypertensionTachycardiaUse in trauma
Etomidate
Painful to injectMore CV stability
Barbiturate
Direct depressantExtended duration of activitySmaller doses
1-2 mg/kgAdd benzodiazepines and narcotic
Benzodiazepines
Quell anxietyHemodynamic stabilityExtended duration of actionPotential for hypoxiaLidocaineEsmolol
Muscle RelaxantsAvoid pancuronium
TachycardiaST segment changes consistent with ischemia
Doxacurium Duration similar to pancuroniumNo cardiovascular effects
Avoid Histamine releasing drugsCurareAtracuriumMivacurium <15 mcg/kgHypotensionTachycardia
Inhalation AgentsPotential for coronary stealAlters coronary autoregulationAlters regional blood flowLittle influence on outcome
Nitrous OxideConstricts coronary arteriesAggravates myocardial ischemiaHigh FiO2 recommended
Maintain saturation at 95-100%
Regional Anesthesia
Monitor patient more accuratelyControl sympathetic responses
FluidsEsmolol
Intraoperative predictors
Choice of anestheticSite of surgeryDuration of AnesthesiaEmergency Surgery
Intraoperative predictors
Choice of AnestheticNo difference in infarction rate GETA vs. Regional
No significant hypotensionNo significant tachycardia
TURPRegional decreased risk post MIReinfarction rate
SAB < 1%GETA 2-8%
Intraoperative predictors
Choice of AnestheticPatient with CHF will benefit from regional technique
SympathectomyDecreased preload
Coronary StealPotent inhalation agents vs. narcotics
Intraoperative predictors
Site of SurgeryThoracic and upper abdominal
2-3 X’s risk of extremity procedures
Duration of Anesthetic> 3 hours > risk of morbidity & mortality
Emergency Surgery2 - 5 X’s greater risk than nonemergent surgery
Cardioactive drugs
NitroglycerinLower LVEDPVasodilatorPoor ventricular function
Esmolol
Control heart rate and blood pressureInductionEmergence
Labetalol
Mixed alpha and betaControl hypertensionHeart rate management
Lidocaine
Blunt effects of intubation1.5 mg/kg 4-6 minutes prior to
intubation
Clonidine
Less hypertensionDecreased anesthesia requirements
Nifedipine
Controlling hypertensionManage coronary artery spasm
Postoperative Management
Maintain analgesiaBalance supply and demandSupplemental oxygenContinue monitoring into postoperative
periodEarly transfusion
Coronary Artery Disease
Major Goal Balance Supply and Demand
Primary Determinants of Myocardial Oxygen DemandWall tension and Contractility
Coronary Artery Disease
Factors modifying coronary blood flowdiastolic timeperfusion pressurecoronary vascular toneintraluminal obstruction
Coronary Artery Disease
Myocardial O2 Extractioninfrequently the cause of ischemia intraoperatively
Arterial O2 ContentCorrection of anemiaHigh FiO2
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
Hemodynamic Goals for the patient with CAD
Rhythm - usually sinusMVO2 - control of demand frequently not
enough, monitor for and treat “supply ischemia
CPB - elevated ventricular filling pressure usually not needed after CABG
Anesthetic Technique
Goals of Anesthesialoss of conciousnessamnesiaanalgesiasuppression of reflexes (endocrine and autonomic)muscle relaxation
Inhalation Agents
AdvantagesMyocardial oxygen balance altered favorably by
reductions in contractility and afterloadEasily titratableCan be administered via CPB machineRapidly eliminated
Inhalation Agents
DisadvantagesSignificant hemodynamic variabilityMay cause tachycardia or alter sinus node functionPossibility of “coronary steal syndrome”
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 depressionMay not be important since Forane reduces SVR,
depresses the myocardium yet maintains CO
Opioids
AdvantagesExcellent analgesiaHemodynamic stabilityBlunt reflexesCan use 100% oxygen
Opioids
DisadvantagesMay not block hemodynamic and hormonal
responses in patients with good LV functionDo not ensure amnesiaChest wall rigidityRespiratory depression
Induction Drugs
BarbituratesBenzodiazepinesKetamineEtomidate
Nitrous Oxide
Rarely used due to:increased PVRdepression of myocardial contractilitymild increase in SVRair expansion
Muscle Relaxants
Used to:facilitate intubationprevent shiveringattenuate skeletal muscle contraction during
defibrillation
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. 98:504-513
04/11/23 WE Ellis 131