ANAESTHETIC MANAGEMENT OF CARDIAC PATIEN

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ANESTHETIC MANAGEMENT OF CARDIAC PATIENTS FOR NON-CARDIAC SURGERY : 

ANESTHETIC MANAGEMENT OF CARDIAC PATIENTS FOR NON-CARDIAC SURGERY ____ Dr.J.Rajaram M.D.

INTRODUCTION : 

INTRODUCTION CVS complications account for 25-50% mortality following non-cardiac surgery MI after non-cardiac surgery is 0.7% & increases to 6% if other risk factor for CAD present Anesthetic management depends on pts pre op clinical risk factors nature of surgery & urgency

CORONARY PERFUSION : 

CORONARY PERFUSION BLOOD FLOWS FROM EPICARDIAL TO ENDOCARDIAL VESSELS CORONARY PERFUSION IS INTERMITTENT AND OCCURS DURING DIASTOLE AVERAGE CBF IS 250ml/min AUTOREGULATES BETWEEN 50-120mmhg , BEYOND WHICH FLOW IS PRESSURE DEPENDENT O2 CONSUMPTION BY BEATING HEART IS 9ml/100g/min AT REST HEART EXTRACTS 70-80% O2.

MYOCARDIAL O2 BALANCE : 

MYOCARDIAL O2 BALANCE FACTORS AFFECTING O2 DEMAND Heart Rate Contractility Diastolic volume Blood Pressure FACTORS AFFECTING O2 SUPPLY Heart Rate Coronary Blood Flow Arterial O2 content Coronary vessel diameter

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DIASTOLIC DYSFUNCTION SYSTOLIC DYSFUNCTION ECG ABNORMALITIES HEMODYNAMIC ABNORMALITIES MYOCARDIAL INFARCTION ISCHEMIC CASCADE ACUTE PLAQUE RUPTURE

VENTRICULAR FUNCTION : 

VENTRICULAR FUNCTION Cardiac output{CO} equated with systolic ventricular function CO=Stroke Volume{SV} × Heart Rate{HR} SV determined by preload, afterload, contractility preload affected by venous return, blood volume Ejection fraction most commonly used measurement of systolic function Diastolic dysfunction recognized by TEE as Prolonged Isovolumetric relaxation time Decreased ventricular compliance &chamber stiffness

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P-V Curve

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A – Normal B – Mitral Stenosis C – Aortic Stenosis D – Mitral Regurgitation E – Aortic Regurgitation

PRESSURE-VOLUME CURVE : 

PRESSURE-VOLUME CURVE POINT A MITRAL VALVE OPENS A-B represents diastolic filling slope of AB implies LV compliance POINT B MITRAL VALVE CLOSES BC represents Isovolumetric contraction POINT C AORTIC VALVE OPENS CD represents stroke volume {SV} POINT D AORTIC VALVE CLOSES DA represents Isovolumetric relaxation ABCD represents external work done by ventricles SV=EDV-ESV & EF=EDV-ESV /EDV

PRE 0P MANAGEMENT : 

PRE 0P MANAGEMENT Optimize IHD pts with anti-anginal drugs like Nitrates, calcium channel blockers, beta-blockers Treat co-morbid conditions like hypertension, diabetic Continue all drugs till surgery except aspirin and clopidogrel Overnight sedation with diazepam Antibiotic prophylaxis in valvular heart disease pts Premedicate with opioid like morphine 0.1-0.15mg/kg and scopolamine 0.2-0.4mg or glycopyrolate 0.2mg Maintain favorable myocardial demand-supply

GENERAL vs. REGIONAL ANESTHESIA : 

GENERAL vs. REGIONAL ANESTHESIA NEURAXIAL ANAESTHESIA Decreases cardiac morbidity due to prevention of thrombosis Decrease in afterload  reduction in O2 consumption Decrease CVS and metabolic stress response Reduction in deep vein thrombosis &post op RS depression Disadvantage – sympathectomy decrease in diastolic BP Clinical trials suggest no difference in infarction rate between GA & RA

MONITORING : 

MONITORING NON-INVASIVE pulse oximetry Non-invasive BP Temperature monitoring End-tidal CO2 monitoring ECG Monitoring TTE/TEE Urine output monitoring-Foley’s catheter INVASIVE Invasive arterial BP monitoring CVP monitoring Pulmonary artery catheterization

ECG MONITORING : 

ECG MONITORING ECG shows rate, rhythm, ST segment changes Lead V5 is single most sensitive lead {80%} Lead II ,V4,V5 – sensitivity 96% ECG changes in ischemia 1mm horizontal/down sloping ST segment depression 2mm ST segment elevation peaked then inverted T waves Q waves in two contiguous leads

TEE : 

TEE DETECTS BOTH GLOBAL & REGIONAL CARDIAC DYSFUNCTION MOST SENSITIVE INDICATOR OF MYOCARDIAL ISCHEMIA REGIONAL WALL MOTION ABNORMALITIES DEVELOP BEFORE ECG CHANGES GIVES INDIRECT MEASUREMENTS OF SV, EF, etc.

INVASIVE MONITORING : 

INVASIVE MONITORING INVASIVE MONITORING INDICATIONS Hemodynamically unstable pts Major surgeries involving large fluid shifts &blood loss Pts. with acid-base &electrolyte imbalance To optimize fluid therapy

INTRA OP MANAGEMENT : 

INTRA OP MANAGEMENT OBJECTIVES Maintain a favorable myocardial O2 supply-demand Optimise preload Avoid tachycardia & hypertension Avoid hypoxia & hypercarbia Prevent stress response during intubation Monitor for ischemia & treat

INTRA OP MANAGEMENT OF COMPLICATIONS : 

INTRA OP MANAGEMENT OF COMPLICATIONS INTRA OP HYPERTENTION &TACHYCARDIA Treat readily reversible causes like inadequate depth, hypoxia, hypercarbia Select hypotensive agents NTG 0.5-1 µg/kg/min SNP 0.5-1 µg/kg/min, esmolol 0.5mg/kg over 1 min INTRA OP MI Avoid hypoxia & ensure oxygenation Treat hypertension & tachycardia NTG 1 µg/kg/min is main stay of treatment Institute anti-platelet, anti-thrombin drugs Intra-aortic balloon pump

INHALATIONAL ANESTHETICS : 

INHALATIONAL ANESTHETICS CAUSES GREATER DEPRESSANT EFFECT IN ABNORMAL THAN NORMAL MYOCARDIUM Decreases myocardial contractility Causes diastolic dysfunction Attenuation of baro-reflex arrythmogenic Decrease systemic vascular resistance INHALATIONAL AGENTS ARE CARDIO-PROTECTIVE Coronary vasodilators Reduce myocardial metabolic demands Protective against reperfusion injury through activation of K-ATP channels Enhance recovery of ‘stunned myocardium’

IV INDUCTION AGENTS : 

IV INDUCTION AGENTS Intra venous agents are vaso dilators Etomidate provides hemodynamic stability Ketamine is induction agent of choice in pts with decreased blood volume cardiac tamponade congenital cyanotic heart disease

CONTD…….. : 

CONTD…….. Induction with BZD provide cardiac stability induction dose – 0.2-0.5mg/kg has NTG like effect preserve CBF & CI Opioids are induction agent of choice in pts with moderate LV dysfunction {75-100 µgms/kg} lack of cardio vascular depression prevent endocrine & metabolic changes{stress response} reversibility with naloxone

MUSCLE RELAXANTS : 

MUSCLE RELAXANTS NON DEPOLARISING MUSCLE RELAXANTS Atracurium causes histamine release  hypotension Pancuronium can be used along with opioid induction to prevent bradycardia Vecuronium is cardio-stable Rocuronium is suitable alternative for rapid sequence induction DEPOLARISING MUSCLE RELAXANTS May precipitate cardiac arrhythmias d/t generalised autonomic stimulation succinyl choline - 1 mg/kg 0.5meq/L rise in K+

VALVULAR HEART DISEASE : 

VALVULAR HEART DISEASE STENOTIC LESIONS Fixed cardiac output state & CO is rate dependant Maintain sinus rhythm &avoid tachycardia Avoid hypoxia and hypercarbia Optimize preload Maintain normal to high afterload Avoid hypovolemia &fluid overload by judicious fluid therapy Avoid myocardial depressants Monitor for ischemia in AS pts Maintain normothermia

CONTD……… : 

CONTD……… REURGITANT LESIONS Maintain sinus rhythm Maintain normal to increased heart rate &avoid bradycardia {80-100 beats/min} Avoid acute increase in after load Optimize preload with judicial fluid therapy Avoid myocardial depressants In LV dysfunction ,augment cardiac contractility with inotrope Avoid hypoxia & hypercarbia Maintain normothermia

EXTUBATION : 

EXTUBATION Maintain adequate oxygenation Slow administration of reversal agents Stress attenuation during extubation also Prevent post op hypoxia / hypercarbia through supplemental O2 Prevent tachycardia & hypertension by providing adequate post op analgesia Prevent hypothermia Monitor with ECG for post op ischemia

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THANK U

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