anaesthesia for cardiac patient undergoing non cardiac surgery
TRANSCRIPT
Dr.Kanchan Chauhan
Associate Professor in Anaesthesiology
INTRODUCTION
Stress due to surgery leads to an increase in cardiac output which can be achieved easily by normal patients, but which results in substantial morbidity and mortality in those with cardiac disease.
Most suitable anaesthetic can be given by understanding different cardiac disease.
The skill with which the anaesthetic is selected and delivered is more important
than the drugs used.
No. of patients with cardiac disease are increasing. due to the fact that the surgery is being performed on older patients in whom the incidence of coronary artery disease (CAD) is higher, and secondly, recent advances in diagnostic technology have allowed us to detect CAD in asymptomatic or mildly symptomatic patients.
With increased awareness and improved cardiac surgical results, patients who have undergone corrective cardiac surgery are also presenting for
noncardiac surgery.
What Should be our Approach ? Preoperative – Pre anaesthetic evaluation, Risk stratification and preparation
Intraoperative – Smooth induction , Smooth recovery , Smooth monitoring
Postoperatively – Cont. monitoring and vigilance
Pre anaesthetic evaluation ASSESSMENT OF PERIOPERATIVE RISK
Goldman Cardiac Risk Index. Lee’s risk stratification criterion Detsky’smodified approach to Goldman index NYHA Classification Canadian Cardiovascular Society Classification
Follow AHA ( American Heart Association) guidelines for perioperative cardiovascular evaluation
Medications : Keep in Mind Continue all antianginals, anti hypertensives Continue anti arrythmics Continue Beta blockers and Statins Continue Aspirin (not in some institue)
Discontinue Diuretics, Digitalis, Oral hypoglycemics, ACE inhibitors
O T Preparation Ready Emergency cardiovascular drugs (iv beta blockers, NTG, SNP, Inotropes,
Ephedrine, Phenylephrine, CCB, anti arrythmics etc.
Cardiac equipments :Defibrillator, Pacemakers, Syringe pump
Monitoring
ECG
Blood Pressure
Temperature
Pulse oximetry
End tidal CO2
Arterial Catheter
Beat to beat blood pressure monitoring
ABGs
Early detection of hypotension
Laboratory studies
HGB & HCT
Electrolytes
Liver function studies
Creatine clearance
Osmolality
PA catheterAssessment of LV Function
Early detection of ischemia“v” waves
Increased PCWP
More accuracy than CVPIntravascular volume problems
Especially in patients with severe lung disease
Transesophageal Echocardiography
Demonstrates regional wall motion abnormalities
Suggestive of ischemia
Most accurate measure of left ventricular volume
Non-invasive Continuous Cardiac Output Monitors
Transesophageal Doppler
Thoracic impedance
Limited
Accuracy is controversial
No information about systemic vascular resistance
Measure CVP
Invasive Monitoring
Temperature
Keep warm
Decreasing temperatureShift Oxygen dissociation curve to left
Hemoglobin retains oxygen at tissue level
Prevent alkalosis
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Preoperative Preparation
AnginaMedications to control it
Blood pressure controlledDiastolic < 95 mm hg
Congestive heart failure treatedDiuretics
Afterload reduction
Bedrest if indicated
Control diabetes
Our Approach 2012 for beta blockers
Continue beta blockers for those already receiving Initiate beta blockers prior to surgery (cautiously) for
patients who would otherwise need them -
Begin low dose as early as possible- >1 week - not day of surgery Titrate to heart rate (60-70) and BP
Carefully follow those on beta blockers in the postoperative period Hypotension Bradycardia Postoperative tachycardia: look first for a treatable cause
(hypovolemia, anemia) rather than just increasing beta blocker dose.
Anesthesia Goal Does technique make a
difference? Laryngoscopy Maintenance Regional anesthesia
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Anesthetic Technique
Goals of Anesthesialoss of conciousness
amnesia
analgesia
suppression of reflexes (endocrine and autonomic)
muscle relaxation
Anesthetic Management
Anaesthetic techniques –
Local anaesthesia
Regional anaesthesia
Combined Regional – General anaesthesia
General anaesthesia
Anesthetic management skills more important than technique.
Safest technique is the one the practitioner does best.
Anaesthetic technique must be based on the type of surgery and the desired haemodynamic goals during anaesthesia.
Role of Local Anaesthesia LA should be with appropriate IV sedation
Large doses of anaesthetic should be avoided - cardiac toxicity - dysrrhythmias and myocardial depression.
Epinephrine with LA - tachycardia, which is undesirable and should be avoided.
Monitored with an ECG, BP and a pulse oxymeter. Supplemental oxygen therapy
Regular verbal contact with patient are important.
Regional Anaesthesia
Intraoperative adverse cardiac events do not differ when general or regional anaesthesia is used.(study shows)
Certain procedures have shown better outcome under RA. E.g.- McLaren et al found no mortality under spinal anaesthesia
for fracture neck femur, versus 25%mortality after GA. Patients with prior MI undergoing transurethral resection of
prostate had <1% reinfarction rate after spinal versus 2-8% after GA.
Regional Anaesthesia RA - loss of sympathetic efferent tone - rapid
haemodynamic deterioration contraindicated in severe aortic stenosis or
hypertrophic obstructive cardiomyopathy.
In a patient with a failing heart who is dependent on sympathetic tone –
central neural blockade can
precipitate cardiac arrest.
Monitor patient more accurately
Control sympathetic responses
Combined Regional-General Anaesthesia Requires a lot of experience on the part of anaesthesiologist.
E.g. - For lower abdominal surgery, a combination of lumbar epidural analgesia and GA can be considered when long surgical procedure, large blood loss or marked hypothermia is anticipated.
The combination of thoracic epidural and GA can be used for upper abdominal, thoracic and major vascular surgery.
The main advantages of epidural blockade are superior postoperative analgesia and less diminution of vital capacity.
Epidural analgesia by suppressing pain improves transmural distribution of regional myocardial blood flow and thus minimizing myocardial ischaemia.
General anesthesia Most common anaesthetic technique used for cardiac
patients undergoing noncardiac surgery. Avoids sympathectomy
Risks with intubation
Sympathetic stimulation
Hypoxia
Increased catecholamines
Loss of subjective monitor
Chest pain
Ischemia
General Anesthesia required
I. Pre-anaesthetic medication Integral part of anaesthetic practice ( particularly in patients with CAD
and hypertension.)
Benzodiazepines –
Quell anxiety
Hemodynamic stability
Extended duration of action
Potential for hypoxia Intravenous narcotics (e.g. Fentanyl)
Effective control of catecholamines
Respiratory depression
Prolonged ventilation
OpioidsAdvantages
Excellent analgesia
Hemodynamic stability
Blunt reflexes
Disadvantages
May not block hemodynamic and hormonal responses in patients with good LV function
Do not ensure amnesia
Chest wall rigidity
Respiratory depression
Inductions AgentsAvoid Ketamine
HypertensionTachycardiaUse in trauma
EtomidatePainful to injectMore Cardiovascular stability
BarbiturateDirect depressantExtended duration of activitySmaller doses
1-2 mg/kgAdd benzodiazepines and narcotic
Propofol Outpatient anaesthesia (quick recovery) Benzodiazepines
Laryngoscopy and intubation Adequate depth of anaesthesia should be ensured prior to
intubation.
Fentanyl 5-8 mgm/kg can be given to blunt the sympathetic responses to
laryngoscopy and intubation.
Lidocaine
Blunt effects of intubation
1.5 - 2 mg/kg 4-6 minutes prior to intubation
Esmolol i.v. – 0.5 to 1mg/kg 90 sec before intubation
Muscle Relaxants Succinylcholine is notorious - producing arrhythmias. Avoid pancuronium
Tachycardia
ST segment changes consistent with ischemia (Pancuronium may be used in patients with CAD who have a slow heart rate) Vecuronium provides minimal haemodynamic alterations. Doxacurium -cardiovascular stable. Rocuronium should be considered during rapid sequence induction
technique.
Avoid Histamine releasing drugs
Curare
Atracurium
Mivacurium <15 mcg/kg
- Hypotension ,Tachycardia
Nitrous Oxideincreased PVR
depression of myocardial contractility
mild increase in SVR
air expansion Constricts coronary arteries
Aggravates myocardial ischemia
High FiO2 recommended Maintain saturation at 95-100%
N2O - Detrimental effects in patients with CHF, pulmonary hypertension and regional myocardial ischaemia
Inhalation Agents
Advantages
Myocardial oxygen balance altered favorably by reductions in contractility and afterload
Easily titratable
Can be administered via CPB machine
Rapidly eliminated
Disadvantages
Significant hemodynamic variability
May cause tachycardia or alter sinus node function
Possibility of “coronary steal syndrome”
Inhalation Agents Depress myocardium, Cause arterial and venous dilation and decrease sympathetic nervous activity.
decrease in BP and CO, and thus decrease in myocardial oxygen consumption.
(advantageous in patients with CAD, may produce cardiovascular collapse in patients with poor myocardial reserve.)
Potential for coronary steal - isoflurane
Alters coronary autoregulation
Alters regional blood flow
Little influence on outcome
Coronary Steal
Arteriolar dilation of normal vessels diverts blood away from stenotic areas
Commonly associated with adenosine, dipyridamole, and SNP
Isoflurane causes steal and new ST-T segment depression
May not be important since Isoflurane reduces SVR, depresses the myocardium yet maintains CO
Intraoperative predictors
Choice of AnestheticNo significant hypotension
No significant tachycardia
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 drugsNitroglycerin
Lower LVEDP , Vasodilator
Esmolol
Control heart rate and blood pressure
Labetalol
Control hypertension , Heart rate management
Clonidine
Less hypertension , Decreased anesthesia requirements
Nifedipine Controlling hypertension Manage coronary artery spasm
Coronary Artery DiseaseMajor Goal
Balance Supply and Demand
Primary Determinants of Myocardial Oxygen Demand
Wall tension and Contractility
Factors modifying coronary blood flow
diastolic time
perfusion pressure
coronary vascular tone
intraluminal obstruction
Hemodynamic Goals for the Patient with CADPreload - keep the heart small, decrease wall
tension, increase perfusion pressure
Afterload - maintain, hypertension better than hypotension
Contractility - depression is beneficial when LV function is adequate
H R - slow
Rhythm - usually sinus
MVO2 - control of demand frequently not enough, monitor for and treat ischemia
Monitored Anaesthesia Care Employed in CAD patients
Patients carrying the highest risk are selected Minimum anaesthetic interference Adequate analgesia is mandatory
Failure to suppress the stress response Highest incidence of 30 day mortality
(isacon 2008)
HEART FAILURE Inability of the heart to pump enough blood to match tissue requirements. Commonest cause ischaemic heart disease. Other causes include hypertension, valvular heart disease and
cardiomyopathies.
Note that with an increase in contractility there is a greater cardiac output for the same ventricular end- diastolic volume.
. Drug treatments may include ACE (angiotensin converting enzyme)
inhibitors, diuretics and nitrates.
Echocardiogram to assess ejection fraction - values of less than 30% equate to severe heart failure.
Anaesthesia consideration Preload can be reduced with diuretics and nitrates, and both
central venous and pulmonary artery pressures can be monitored.
Trans-oesophageal echocardiography, if available, is a useful tool to visualize overall cardiac performance.
Maintenance of myocardial contractility - in particular inotropes may be needed to oppose the cardiodepressant action of anaesthetic agents.
Reduction of afterload by vasodilation, for example as a secondary effect of spinal or epidural anaesthesia. This not only reduces myocardial work, but helps maintain cardiac output. However, the benefit of such actions may be limited by falls in blood pressure which can compromise blood flow to vital organs such as the brain and kidneys. So balance should be there
Valvular Heart Disease
Aortic Stenosis
Aortic Insufficiency
Mitral Stenosis
Mitral regurgitation
Mitral Stenosis
Characterized by:
Normal ventricular function
Obstruction to left atrial emptying decreases cardiac output
Pulmonary congestion from elevations in LA and pulmonary venous pressure
Pulmonary hypertension and RVH over time
Hemodynamic Goals for the Patient with MSPreload - Enough to maintain flow across stenotic valve so
to maintain ventricular feeling, excess fluid may cause pulmonary edema
Afterload – SVR should be maintained,avoid decrease in SVR
Avoid increased RV afterload (PVR)
Contractility - LV usually ok until after CPB, with longstanding PHTN, RV may be impaired
HR -keep slow to allow time for ventricular filling, AVOID SINUS TACHYCARDIA
Hemodynamic Goals for the Patient with MS Rhythm - Often atrial fibrillation, control ventricular
response
MVO2 - Not a problem
CPB - Vasodilators may help post-CPB RV failure, control of ventricular response may be difficult
epidural preffered over spinal
phenylephrine preffered over ephedrine
Mitral Regurgitation
Characterized by:
Chronic volume overload similar to AI
Increased ventricular compliance without change in LVEDP
May mask signs of impaired ventricular function
Hemodynamic Goals for the Patient with MIPreload – maintain or slightly increase ;an elevated preload
may cause increase in regurgitant flow and low preload may cause inadequate cardiac output Usually pretty full, may need to keep that way
Afterload - Decreases are beneficial, increases augment regurgitant flow, avoid sudden increase in SVR
Contractility - Unrecognized myocardial depression possible, titrate myocardial depressants carefully, maintain or increase to decrease left ventricular volume
HR – maintain or increase , avoid bradycardia which worsens regurgitant flow
Hemodynamic Goals for the Patient with MIRhythm - Atrial fibrillation is occasionally a problem
MVO2 - only if associated with CAD, then caution!
CPB - New valve will increase afterload, unmasking impaired ventricle
Spinal and epidural well tolerated but avoid bradychardia
Mitral valve prolapse- anaesthesia consideration Aboid decrease in preload
Continue antiarrhythmic drugs
Same consideration as for MI
Aortic Stenosis
Characterized by:
Obstruction to LV outflow
Intraventricular systolic pressure and wall tension increase
Concentric hypertrophy
Decreased LV compliance
Reliance on atrial contribution
Hemodynamic Goals for the Patient with ASPreload - full, adequate intravascular volume to fill
noncompliant ventricle and to maintain BP
Afterload - already elevated but relatively fixed, coronary perfusion pressure must be maintained,
Contractility - usually not a problem, inotropes may be helpful preinduction in end-stage AS with hypotension
Watch out for vasodilation
Treat hypotension with phenylephrine
Hemodynamic Goals for the Patient with ASRate - not too slow (decrease CO), not too fast
(ischemia)
Rhythm - Sinus!! Cardioversion if hemodynamic instability from SV dysrhythmias
MVO2 - Ischemia is an ever present risk, Avoid tachycardia and hypotension
Mild to moderate may tolerate spinal and epidural (epidual preferred)
spinal and epidural contraindicated in severe AS
High risk of myocardial ischaemia
Aortic InsufficiencyCharacterized by:
Chronic volume overload
Ventricular dilatation
Eccentric hypertrophy
Forward stroke volume higher than normal causing increased systolic pressure
Regurgitation across the valve causes diastolic pressure to be lower than normal
Hemodynamic Goals for the Patient with AIPreload - normal to slightly increased to maximize
forward cardiac output and maintain BP
Afterload - Reduction beneficial with anesthetics or vasodilators,increases augment regurgitant flow, avoid sudden increase in afterload
Contractility - usually adequate
Rate - Modest tachycardia shortens diastolic phase decreases regurgitant fraction and increases cardiac output
Most patient tolerate spinal or epidural provided intravascular volume is maintained
Aortic Insufficiency Once asymptomatic death can occur with in 5 yrs
unless lesion is surgically repaired
Digitalis , Diuretics and afterload reduction (ACE inhibitors) for chronic cond. (eventual surgical repair)
Inotropes (dopamine,dobutamine) and vasodilators for severe,chronic aortic regurgitation
(requires surgery)
Hemodynamic Goals for the Patient with AI Rhythm - usually sinus, not a problem
MVO2 - Not usually a problem
CPB - observe for ventricular distention (decreased HR, increased ventricular filling pressure) when going onto bypass
Hypertension – Anaesthesia consideration
HTN (defined as a diastolic BP>90mmHg or a systolic BP>140mmHg in adults) is the most common of all the cardiovascular diseases.
Most patients are under adequate control preoperatively and their medication should be continued till the day of surgery.
Poorly controlled or uncontrolled hypertensives are at increased risk of perioperative complications such as ischaemia, MI, arrhythmias and cerebrovascular accidents (CVA).
In mild hypertensive patients a single dose of long acting beta-blocker may reduce the risk of myocardial ischaemia during stressful periods.
However, in patients with moderate to severe HTN, cardiology consultation should be obtained and BP brought under control prior to elective surgery.
Coronary Artery Revascularization Prophylaxis Trial (CARP)
Coronary revascularization prior to vascular surgery is not of benefit in the patient with stable CAD if treated with beta blockers, aspirin, statins in the absence of: unstable coronary diseaseleft main coronary diseaseaortic stenosissevere left ventricular dysfunction
Elective vascular surgery in high risk patients.101 patients3 or more cardiac risk factorsAll with extensive inducible ischemia by stress test43% with LVEF < 35%75% with Left main or 3-vdAll received beta blocker titrated to HR 60-65Antiplatelet agents continued in perioperative period
No benefit of prophylactic coronary revascularization
How about the patient who has already received a stent and requires noncardiac surgery ?
Drug eluting stent related issues
Stent thrombosisASA + clopidogrel
HemorrhageASA + clopidogrel
Joint Advisory Recommendations and Noncardiac Surgery Consider bare metal stent if patient requires PCI and is
likely to require invasive or surgical procedure within next 12 months.
Educate patient prior to discharge re: risk of premature antiplatelet discontinuation
Instruct patient to contact treating cardiologist before antiplatelet discontinuation
Healthcare providers who perform surgical or invasive procedures must be made aware of catastrophic risks of premature antiplatelet discontinuation and should contact the treating cardiologist to discuss optimal management strategy
Joint Advisory Recommendations and Noncardiac Surgery
Defer elective procedures for which there is bleeding risk until completion of antiplatelet course 1 month bare metal stent 12 months drug eluting stent
For patient with drug eluting stent who are to undergo procedures that mandate discontinuation of thienopyridine (eg, clopidogrel), continue aspirin if at all possible and restart thienopyridine as soon as possible
No evidence for “bridging therapy” with antithrombins, warfarin, or glycoprotein IIb/IIIa agents
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
Postoperative Management
Maintain analgesia
Balance supply and demand
Supplemental oxygen
Continue monitoring into postoperative period
Early transfusion
Key Points Clearance. Perform evaluation and make recommendations that
will relate to perioperative and long – term issues.
Tests only if likely to influence treatment.
Preoperative coronary revascularization if independently indicated.
Selective use of beta blockers. (beware bradycardia)
Statins Beware of premature antiplatelet discontinuation in the patient
post PTCA stent.
Continue beta blocker, aspirin, statins,
Summary Patients with cardiac disease present for
anaesthesia every day.
Since their perioperative courses are associated with greater morbidity and mortality, it is important to provide a haemodynamically stable anaesthetic
This requires knowledge of the pathophysiology of the disease, and of the drugs and procedures and their effects on the patient.
THANKS