Perioperative Hypotension and Myocardial Ischemia Dr Perioperative Hypotension

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Perioperative Hypotension and Myocardial Ischemia Dr. 黃啟祥 台大醫院 麻醉部

Perioperative Hypotension and Myocardial Ischemia Dr. 黃啟祥 台大醫院 麻醉部

Perioperative Hypotension

Perioperative Hypotension

Assess Severity • Is the degree of hypotension SERIOUS? – 20% or more below

Assess Severity • Is the degree of hypotension SERIOUS? – 20% or more below baseline values – If YES then validate reading (if possible) • Associated with end organ ischemia – – – Drowsiness / Confusion / Agitation Nausea Angina / ST segment change If YES then proceed to critical management Otherwise manage as mild to moderate hypotension 3

Hypotension Validation • Check NIBP monitor – Repeat cycle, check cuff size, check manually

Hypotension Validation • Check NIBP monitor – Repeat cycle, check cuff size, check manually • Confirm with palpation of large artery for pulse – If no pulse, manage as for CARDIAC ARREST • Check arterial line – Flush, open to air and quickly confirm zero, pulsatile waveform • Independent pulse source – Sp. O 2 • Has ETCO 2 level fallen? – Low ETCO 2 = Low cardiac output or Embolism 4

Critical Management I • Increased inspired OXYGEN • Is the hypotension EXPECTED? – Is

Critical Management I • Increased inspired OXYGEN • Is the hypotension EXPECTED? – Is it the result of an anticipated surgical intervention? – If YES then manage in context of surgical causes • If UNEXPECTED, quickly check that there are no obvious surgical issues e. g. – – – Sudden massive blood loss IVC compression (including obstetrics / laparoscopy) Femoral shaft reaming etc. CO 2 insufflation Tourniquet or Vascular Clamp release 5

Critical Management II Check EKG • If Asystole / VF or pulseless VT then

Critical Management II Check EKG • If Asystole / VF or pulseless VT then manage CARDIAC ARREST • If TACHYARRHYTHMIA (AF/SVT/VT) then – Control rate with Vagal Manouvres / Vagotonic Drugs or Synchronized Cardioversion – Review possible causes including LIGHT ANAESTHESIA • If SEVERE BRADYCARDIA then – Increase rate with vagolytic agents (atropine) – Use chronotropic pressors (ephedrine, adrenaline) – Review possible causes including HYPOXIA 6

Critical Management III Provide circulatory support in presence of normal rhythm • Volume resuscitation

Critical Management III Provide circulatory support in presence of normal rhythm • Volume resuscitation – – First priority in context of recent neuraxial block IV fluids Posture legs up (if practical) Consider wide bore access • Vasopressors – Especially if GA or unresponsive to volume or limited ability to rapidly infuse fluids – Ephedrine / Metaraminol / Phenylephrine / Noradrenaline / Adrenaline / Vasopressin 7

Critical Management IV Assess CAUSE and provide SPECIFIC treatment • Consider likely causes of

Critical Management IV Assess CAUSE and provide SPECIFIC treatment • Consider likely causes of SEVERE HYPOTENSION – Sudden BLOOD LOSS (surgical) – Impaired VENOUS RETURN (surgery / posture / high airway pressures / pneumothorax) – VASODILATION (neuraxial block assess block height, anesthetic agents, drug reactions including ANAPHYLAXIS) – EMBOLISM (Air / CO 2 / orthopedic / venous thromboembolism) – CARDIAC ARRHYTHMIA – CARDIAC Dysfunction – Ischemia / Infarction – Depressants (anesthetic agents etc) 8

Critical Management V Continue to Support Blood Pressure • If still severely hypotensive –

Critical Management V Continue to Support Blood Pressure • If still severely hypotensive – Call for assistance – Review Likely Causes • If cause still not determined : Perform Systematic Review of – AIRWAY: pressure, minute volume – BREATHING: CO 2 exchange, oxygenation – CIRCULATION: rhythm, ischemia, volume (insert CVP, PAC, TEE) – DRUGS: check doses, agent • Consider other RARE CAUSES 9

Non Critical Management I • Validate reading • Attempt to IDENTIFY CAUSE • Treat

Non Critical Management I • Validate reading • Attempt to IDENTIFY CAUSE • Treat by – CORRECTING CAUSE – DECREASING ANESTHETIC DEPTH (if GA) – VOLUME (IV or posture) – VASOPRESSORS (if unresponsive to other measures) 10

Non Critical Management II • Identify and treat COMMON CAUSES of mild to moderate

Non Critical Management II • Identify and treat COMMON CAUSES of mild to moderate intraoperative hypotension – Relative HYPOVOLAEMIA • Neuraxial BLOCK (assess block height), inadequate fluid replacement – Excessive relative DEPTH of ANESTHESIA • Volatile agent / IV agent too high – High AIRWAY PRESSURES – SURGICAL • Blood loss, venous return compression, release of tourniquet or vascular clamp – Mild RHYTHM disturbance • Nodal rhythm, slow AF 11

Non Critical Management III • If unable to identify a cause at this stage,

Non Critical Management III • If unable to identify a cause at this stage, proceed to a more thorough systematic assessment – Perform Systematic Review of • AIRWAY: pressure, minute volume • BREATHING: CO 2 exchange, oxygenation • CIRCULATION: rhythm, ischemia, volume (insert CVP, PAC, TEE) • DRUGS: check doses, agent – Consider RARE CAUSES 12

Rare Causes of Intraoperative Hypotension • • Anaphylaxis Drug Error Transfusion Incompatibility Acute Mitral

Rare Causes of Intraoperative Hypotension • • Anaphylaxis Drug Error Transfusion Incompatibility Acute Mitral Valve Rupture Pericardial Tamponade Septic Shock Adrenocortical Insufficiency 13

Perioprative Myocardial Ischemia

Perioprative Myocardial Ischemia

Importance of perioperative myocardial ischemia • Adverse cardiac events are major cause of post

Importance of perioperative myocardial ischemia • Adverse cardiac events are major cause of post surgical morbidity and mortality • Perioperative ischemia (esp postoperative and prolonged) is associated with adverse cardiac events (early and late) • Most perioperative ischemia is silent • Real time detection may allow therapeutic intervention 15

Patients at Risk • Known coronary artery disease (CAD) • Increased risk of CAD

Patients at Risk • Known coronary artery disease (CAD) • Increased risk of CAD – Diabetes, hypertension, smoking, hyperlipidemia, family history of CAD, peripheral vascular and cerebrovascular disease • Increased risk of cardiovascular complications – Renal insufficiency, age > 65, history of cardiac failure, poor functional capacity (<4 METS), abnormal ECG • Surgical factors – Major urgent surgery, vascular surgery (inc peripheral), significant fluid shifts, blood loss 16

Risk Reduction Strategies 1 • Sympathetic modulation avoid tachycardia – BETA BLOCKADE – Alpha

Risk Reduction Strategies 1 • Sympathetic modulation avoid tachycardia – BETA BLOCKADE – Alpha 2 agonists – ? Anxiety control (premed), Good analgesia, Epidural (local anes) • Maintain normothermia postoperatively • Hemoglobin > 9 10 g/d. L • Avoid hypoxia prolonged supplemental O 2 (maybe > 3 days) 17

Risk Reduction Strategies 2 • Coagulation modulation – – Sympathetic modulation Aspirin, ketorolac Heparin

Risk Reduction Strategies 2 • Coagulation modulation – – Sympathetic modulation Aspirin, ketorolac Heparin Warfarin • Periop period is a hypercoagulable state thrombosis involved in pathogenesis of acute coronary syndromes and platelet inhibitors and anticoagulants are used to treat acute coronary syndromes 18

How to Monitor for Ischemia • Symptoms: usually none – Pain, SOB, sweating, N

How to Monitor for Ischemia • Symptoms: usually none – Pain, SOB, sweating, N &V, altered mentation • Clinical signs: usually none – Sweating, CHF, HR changes, arrhythmias, hypotension • ECG: key perioperative monitor • Pulmonary artery catheter – Increased PCWP, new V waves on PCWP tracing • TEE – SWMA, change in mitral regurgitation, diastolic dysfunction, decrease in global contractility 19

ECG Monitoring for Ischemia 1 Optimal use • Lead selection II and V 4

ECG Monitoring for Ischemia 1 Optimal use • Lead selection II and V 4 or V 5 (3 lead modified V leads e. g. CM 5) • Correct electrode positioning • Good electrode application • Calibration (1 m. V = 1 cm) • Mode: diagnostic • Printout baseline and any changes • Automated ST segment analysis – Always review measurement points to verify ST segment changes 20

ECG Cables Monitoring cable connections Europe Red Yell ow Gree n Blac k Whit

ECG Cables Monitoring cable connections Europe Red Yell ow Gree n Blac k Whit e Connect to: Right Arm Left Leg Right Leg Chest U. S. A. Whi te Blac k Red Gre en Bro wn 21

Lead CM 5 22

Lead CM 5 22

ECG Monitoring for Ischemia 2 Ischemic Manifestations • ST SEGMENT CHANGES (most specific) •

ECG Monitoring for Ischemia 2 Ischemic Manifestations • ST SEGMENT CHANGES (most specific) • T wave changes – esp inversion in high risk groups • • Arrhythmias New conduction abnormalities New atrioventricular block Heart rate changes 23

ECG Monitoring for Ischemia 3 ST Segment Criteria for Ischemia • Depression: subendocardial ischemia,

ECG Monitoring for Ischemia 3 ST Segment Criteria for Ischemia • Depression: subendocardial ischemia, poor localization – Horizontal / downsloping depression > 0. 1 m. V (1 mm) at 60 80 msec after J point – Upsloping depression > 0. 15 m. V at 80 msec after J point • Elevation: transmural ischaemia, good localization – > 0. 1 m. V at 60 80 msec after J point 24

J Point and ST Segment 25

J Point and ST Segment 25

ECG monitoring for Ischemia 4 Other Causes of Acute ST Segment Changes • •

ECG monitoring for Ischemia 4 Other Causes of Acute ST Segment Changes • • • Conduction disturbances R wave amplitude changes Hyperventilation Electrolyte changes, hypoglycemia Hypothermia (< 30º) Body position changes / retractors Autonomic NS changes e. g. spinal Myocardial infarction or contusion Neurological changes (trauma, SAH) Acute pericarditis 26

ECG Monitoring for Ischemia 5 Causes of Chronic ST Segment Changes • Non specific

ECG Monitoring for Ischemia 5 Causes of Chronic ST Segment Changes • Non specific changes V 4 most likely to be isoelectric • LVH • Early repolarization pattern • Digitalis • Bundle branch blocks esp LBBB • Old myocardial infarction • LV aneurysm 27

Management of Suspected Intraoperative Ischemia • FIRSTLY – Secure system ensure adequate oxygenation, BP,

Management of Suspected Intraoperative Ischemia • FIRSTLY – Secure system ensure adequate oxygenation, BP, volume, Hb • SECONDLY – Verify change – Optimize hemodynamics especially tachycardia and blood pressure • THIRDLY, consider – – – Increase Fi. O 2 NTG Increased monitoring CVP, PCWP, TEE Inform surgeon, alter surgical plan Postoperative management 28

Management of Suspected Intraoperative Ischemia Verify Change • Check ECG (calibration, mode, previous ECG

Management of Suspected Intraoperative Ischemia Verify Change • Check ECG (calibration, mode, previous ECG printouts) • Verify automatic ST segment analyses • Look for associated features – Arrhythmias, hypotension – Increased filling pressures or new V waves – TEE changes (check all LV segments) • Consider – Other causes of ECG change – Patient’s risk of CAD 29

Management of Suspected Intraoperative Ischemia Tachycardia management • FIRSTLY treat cause e. g. hypovolemia,

Management of Suspected Intraoperative Ischemia Tachycardia management • FIRSTLY treat cause e. g. hypovolemia, anesthetic depth, CO 2 • NEXT: – Beta blockade (aim for HR < 60) – Esmolol 0. 25 0. 5 mg. kg bolus, 25 300 mg/kg/min infusion atenolol 0. 5 10 mg titrated bolus over 15 minutes – Metoprolol 1 15 mg titrated bolus over 15 minutes • If beta-blockade contraindicated – Verapamil 2. 5 mg repeat as needed. Infuse at 1 10 mg/hr [may be first choice if ST segment elevation (coronary spasm)] – alpha 2 agonists clonidine, dexmedetomidine 30

Management of Suspected Intraoperative Ischemia BP management • Hypotension – Treat cause e. g.

Management of Suspected Intraoperative Ischemia BP management • Hypotension – Treat cause e. g. hypovolemia, anesthetic depth, PEEP, surgical manipulation – Vasopressors (metaraminol, phenylephrine) (inotropes with caution as increase O 2 demand) • Hypertension – – – Treat cause e. g. anesthetic depth, CO 2 NTG sublingual (0. 3 0. 9 mg works within 3 min) IV infusion (0. 25 4 mg/kg/min titrate to effect) Clonidine (30 mg every 5 minutes up to 300 mg) Dexmedetomidine (1 mg/kg load, infuse at 0. 2 0. 7 mg/kg/hr) 31

Management of Persistent Ischemia If Ischemia Persists with Optimal Hemodynamics • Keep increasing NTG

Management of Persistent Ischemia If Ischemia Persists with Optimal Hemodynamics • Keep increasing NTG (may combine with vasopressor if hypotension) • May increase monitoring CVP, PCWP, TEE • CONSIDER Acute Coronary Syndrome (unstable angina, infarct) – Aspirin or ketorolac – Heparin (5000 U bolus, then 1000 U/hr) if surgery permits – Continue beta blockade (aspirin & beta blockade reduce risk of infarct and mortality) – Observe for complications arrhythmias, CHF, infarct – Cardiology consult urgent reperfusion within 12 24 hours (especially if persistent ST segment elevation) • PTCA most practical (thrombolysis CI after surgery) – ? IABP 32

Postoperative Management of Perioperative Ischemia • CONSIDER – – ICU or CCU postop and/or

Postoperative Management of Perioperative Ischemia • CONSIDER – – ICU or CCU postop and/or cardiology referral Surveillance for periop MI ECG immediately postop and on day 1 and 2 Cardiac troponin at 24 hrs and day 4 (or hosp discharge) (CK MB of limited use) • LONG TERM – Letter to GP / cardiologist – Risk factor management – Aspirin, statins, beta blockade, ACE inhibitors 33

THE END

THE END