Anesthesia Cases

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Anesthesia Cases
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The Case

• A 68-year-old woman with multiple cardiac risk
  factors had sudden onset of crushing substernal
  chest pain.
• Despite aggressive thrombolytic therapy, the
  patient had electrocardiogram (ECG) evidence of a
  transmural anterolateral myocardial infarction
  (MI).
• Three weeks following the MI, the patient
  develops acute cholecystitis, and presents for a
  cholecystectomy.

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QUESTIONS

• 1.How do you evaluate the cardiac risk in a
  patient scheduled for noncardiac surgery?
• 2.What is the cardiac risk in this patient? What
  additional investigations should be performed?
• 3.What are the implications for anesthetic
  management when coronary revascularization is
  performed before noncardiac surgery?

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QUESTIONS

• 4.What intraoperative monitors would you use?
• 5.What additional drugs would you have prepared?
• 6.What anesthetic technique would you use?
• 7.How would you manage this patient
  postoperatively?

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How do you evaluate the cardiac risk in a
patient scheduled for noncardiac surgery?
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Preoperative Cardiac Evaluation

• The cornerstone of preoperative cardiac
  evaluation includes
• Review of history
• Physical examination
• Diagnostic tests
• Knowledge of the planned surgical procedure.

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Preoperative Cardiac Evaluation

• Is readily available, inexpensive, easy to
  perform and able to interpret and detect previous
  myocardial infarction, acute ischaemia, or
  arrhythmias.
• The presence of abnormalities such as Q waves and
  non sinus rhythms has been shown to correlate
  with adverse postoperative cardiac events.

Preoperative Resting Electrocardiogram
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Stepwise approach to preoperative cardiac
assessment
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What is the cardiac risk in this patient? What
additional investigations should be performed?
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Perioperative cardiac risk

• Pt factors major risk (recent MI)
• Surgical factors major intraperitoneal surgery
  is an intermediate risk.

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Additional Tests

• Stress tests
• Exercise stress test
• Pharmacological
• Dobutamine stress echocardiography.
• Dipyridamole thallium scintigraphy.

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Additional Tests

• Preoperative coronary angiogram / coronary
  intervention
• The decision for or against preoperative
  angiogram, coronary revascularization,
  percutaneous interventions (PCI) or coronary
  artery bypass grafting (CABG), should be based
  entirely on universally accepted medical
  indications for coronary revascularization and
  the appropriate technique.

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Coronary angiography in this case is class (I)
According to ACC/AHA guidelines for PCI after
thrombolysis, as formation of Q waves in ECG
after thrombolysis is considered an evidence of
ischemia.
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• What are the implications for anesthetic
  management when coronary revascularization is
  performed before noncardiac surgery?

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Anesthetic implications of revascularization

• Prophylactic coronary revascularization in
  patients with asymptomatic CAD before major
  surgery has no benefit.
• Revascularization by CABG or PCI must be
  justified according to long term outcome.
• PCI- angioplasty is now often accompanied by
  stenting which require post procedure
  antiplatelet therapy to prevent acute coronary
  thrombosis.

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Recommendations for timing of non-cardiac surgery
after PCI. PCI percutaneous coronary intervention
Anesthesiology 2008109596604
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Anesthetic implications of revascularization

• So if BMS to be inserted elective surgery is
  recommended to postpone for 6-8 wks.
• If DES to be inserted, elective surgery is
  recommended to be postponed for at least 12
  months.
• Revascularization by CABG, postpone elective
  surgery for 3-6 months.

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• What intraoperative monitors would you use?

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Monitoring

• An important goal of when selecting
  intraoperative monitors for patient with ischemic
  heart disease is select those that allow early
  detection of myocardial ischemia.
• Electrocardiography the simplest, most cost
  effective method to detect myocardial ischemia by
  focusing changes in ST-segment changes

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Monitoring

• ST-segment changes such as depression or
  elevation of at least 1mm.
• The degree of ST segment depression parallels
  the severity of myocardial ischemia.
• Visual detection of ST segment IS unreliable,
  computerized ST segment analysis has been
  incorporated in electrocardiography monitor.
• Traditionally, monitoring two leads, II and V5
  has been standard.

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• The lead sensitivity in detecting myocardial
  Ischemia is displayed,
• The combination of lead II and V5 Provides the
  greatest ability to detect ischemia and Rhythm
  disturbances.

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Intraoperative monitors

• Pulse oximetry ( to assess arterial oxygenation).
• Invasive blood pressure (for early detection of
  hemodynamic instability)
• Capnography (to determine continual end-tidal CO2
  analysis specially if laparoscopic
  cholecystectomy was the selected procedure)
• Body temperature (to avoid intraoperative
  hypothermia which predispose to shivering on
  awaking, leading to abrupt increase in oxygen
  consumption )

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Intraoperative monitors

• Urine output using Foleys catheter.
• PAC a number of studies reported that PAC is an
  insensitive monitor for myocardial ischemia and
  should not be inserted for this as a primary
  indication.
• TEE by detection of new wall motion abnormality.
  It's use here is not beneficial as it must be
  inserted after induction and removed before
  extubation, thus missing the critical time of
  hemodynamic changes, also deep gastric views will
  interfere with the surgical field.

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Q5What additional drugs would you have prepared?

• Drugs used in treatment of intraoperative
  myocardial ischemia must be available, and
  treatment should be instituted when there are 1
  mm ST segment changes on ECG.
• Aggressive pharmacological treatment of changes
  in heart rate and/or blood pressure is indicated.
• A persistent increase in heart rate can be
  treated by intravenous administration of beta
  blocker such as esmolol.

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Q5What additional drugs would you have prepared?

• Nitroglycerine is more than appropriate when
  myocardial ischemia is associated with normal or
  elevated blood pressure. Nitroglycerine induce
  coronary vasodilation and decrease in preload
  facilitate improvement of subendocardial blood
  flow.
• Sympathomimetic drugs must be available to treat
  hypotension to restore coronary perfusion
  pressure, also fluid infusion can be usful to
  help restore blood pressure.

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Q6What anesthetic technique would you use?

• The basic challenge during anesthesia in patient
  with ischemic heart disease are
• To prevent myocardial ischemia by optimizing
  myocardial oxygen supply and reducing myocardial
  oxygen demand.
• To monitor for ischemia and to treat ischemia if
  it develops.

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Q6What anesthetic technique would you use?

• So avoid tachycardia as it increase oxygen
  requirements and decrease the diastolic time and
  thus the coronary blood flow.
• Avoid hyperventilation, because hypocapnia may
  cause coronary artery vasoconstriction.
• Intraoperative events associated with systolic
  hypertension, arterial hypoxemia, hypotension can
  adversely affect patients with ischemic heart.

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Laparoscopic versus open cholecystectomy

• The main hemodynamic alterations during
  laparoscopy is increase in systemic vascular
  resistance slight decrease in the cardiac output
  which proportionate with intraperitoneal
  pressure.
• For those patients postoperative benefits of
  laparoscopy must be balanced against
  intraoperative risk when choice laparoscopy
  versus laparotomy.

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Laparoscopic versus open cholecystectomy

• Over the past years , patient with progressively
  more severe cardiac disease have safely undergone
  laparoscopy. Because of improved knowledge of
  hemodynamic repercussions of pneumoperitoneum.

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Laparoscopic versus open cholecystectomy

• So if laparoscopy is used
• Slow insufflation.
• Low intraabdominal pressure.
• Hemodynamic optimization before pneumoperitoneum.
• Patient tilt after insufflation.
• Vasodilator drugs and sympathomimetic drugs must
  be available.

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Anesthetic technique.

• The laparoscopic cholecystectomy can be performed
  safely under spinal anesthesia as the sole
  anesthetic procedure and also showed the
  superiority of spinal anesthesia in postoperative
  pain control compared with the standard general
  anesthesia.
• Also laparoscopic cholecystectomy has been
  reported performed under thoracic epidural
  anesthesia in patient with respiratory disease.

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Segmental thoracic spinal anesthesia

• A new technique introduced by Van Zandert in
  2006, a case report of laparoscopic
  cholecystectomy in a patient with severe
  respiratory lung disease. 1 ml plain bupivacaine
  plus sufentanil 2.5 µg (0.5 ml) injected
  intrathecally at the level of 10 th thoracic
  interspinous space.
• Within 3 min a segmental sensory (pinprick)
  block, extending between the third thoracic and
  second lumbar dermatomes, was obtained, but
  without any motor weakness in the legs or hint of
  respiratory distress.

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Segmental thoracic spinal anesthesia

• Mean arterial pressure changes

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Segmental thoracic spinal anesthesia

• Postoperative pain

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Postoperative management

• The postoperative period appears to present the
  highest risk for cardiac morbidity and mortality.
• During this period, 67 of the ischemic events
  occurs.
• This period characterized by increase in heart
  rate, blood pressure, sympathetic discharge and
  hypercoagulability.

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Postoperative management

• Postoperative myocardial ischemia occurs in about
  33 of high risk patient.
• Most of Those events (50) are silent.
• Most cardiac events occurs in the first 48 hours
  postoperatively, delayed cardiac events can occur.

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Postoperative management

• The goals of postoperative management are the
  same as intraoperative management
• Prevent ischemia
• Monitor ischemia
• Treat ischemia
• Shivering, pain, hypoxemia, hypercarbia, sepsis
  and hemorrhage lead to increased oxygen supply /
  demand imbalance which in turn precipitate
  myocardial ischemia.

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Postoperative management

• Effective pain management is essential to prevent
  adverse outcomes.
• PCA and PCEA are the most effective.
• Effective pain management leads to a reduction
  in postoperative catecholamine surge and
  hypercoagulability.

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Postoperative management

• Patient with ischemic heart disease is adversely
  affected by anemia. Evidence suggest that
  transfusion are rarely beneficial if hemoglobin
  level exceeds 10 gm.
• Avoid postoperative hypothermia and hypovolemia.

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Postoperative management

• Measurement of biomarkers of cardiac injury.
• They are normally not present in the plasma so
  high signal to noise ratio.

Cardiac specific Troponin I and T is the
preferred marker due to high sensitivity.
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