Anesthesia Cases

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.

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?

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?

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

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

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

Stepwise approach to preoperative cardiac assessment

What is the cardiac risk in this patient What is the cardiac risk in this patient? What additional investigations should be performed?

Perioperative cardiac risk: Pt factors: major risk (recent MI) Surgical factors: major intraperitoneal surgery is an intermediate risk.

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

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.

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.

What are the implications for anesthetic management when coronary revascularization is performed before noncardiac surgery?

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.

Recommendations for timing of non-cardiac surgery after PCI Recommendations for timing of non-cardiac surgery after PCI. PCI= percutaneous coronary intervention Anesthesiology 2008;109:596–604

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.

What intraoperative monitors would you use?

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;

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.

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.

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 )

Intraoperative monitors Urine output : using Foley`s 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.

Q5:What 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.

Q5:What 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.

Q6:What 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.

Q6:What 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.

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.

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.

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.

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.

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.

Segmental thoracic spinal anesthesia Mean arterial pressure changes

Segmental thoracic spinal anesthesia Postoperative pain

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.

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.

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.

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.

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.

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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