Noncardiovascular Surgery for the Cardiac Patient Wayne E. Ellis, Ph.D., CRNA

Noncardiovascular Surgery for the Noncardiovascular Surgery for the Cardiac PatientCardiac Patient

Wayne E. Ellis, Ph.D., CRNAWayne E. Ellis, Ph.D., CRNA

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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 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

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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

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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 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

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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 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.

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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 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

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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

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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

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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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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

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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

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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 ExaminationPhysical Examination

CardiovascularCardiovascularJVDJVDCarotid BruitsCarotid BruitsMurmursMurmursS3, S4, Click, RubS3, S4, Click, RubPitting EdemaPitting EdemaPulsesPulsesVascular AccessVascular Access

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Physical ExaminationPhysical Examination

PulmonaryPulmonaryWheezesWheezesRalesRalesRhonchiRhonchiA-P DiameterA-P Diameter

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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 >7 positive

• Associated diseases–Diabetes, thyroid disease

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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 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

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MonitoringMonitoring

RoutineRoutinePulse OximetryPulse OximetryPNSPNSCapnographyCapnographyTemperatureTemperature

Core and peripheralCore and peripheral

ECGECGLeads V5 and IILeads V5 and II

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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

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Physical signsPhysical signsJugular distentionJugular distentionChest soundsChest sounds

RalesRalesExtra heart soundsExtra heart sounds

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Preoperative EvaluationPreoperative EvaluationHistoryHistoryPhysical assessmentPhysical assessmentEKG evaluationEKG evaluationExercise toleranceExercise toleranceChest X-rayChest X-rayLab studiesLab studies

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Preoperative EvaluationPreoperative Evaluation

Current MedicationCurrent MedicationBeta-blockersBeta-blockersCalcium Channel BlockersCalcium Channel BlockersAntidysrhythmia agentsAntidysrhythmia agentsNitratesNitratesDiureticsDiureticsAntihypertensive agentsAntihypertensive agents

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DyspneaDyspnea

ActivityActivityRestRestWhat starts itWhat starts itHow long lastsHow long lasts

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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

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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

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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

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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

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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 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

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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

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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

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