Simulation Scenario Template



UCI Simulation Scenario

Subarachnoid Block post

Orthotopic Heart Transplant (OHT)

Demographics

Case Title: Myocardial Ischemia in a Patient with a Cardiac Transplant after Subarachnoid Block

Patient Name: Gonzalo Higuain

Case Description & Diagnosis: An 80-year-old male s/p cardiac transplant 13 years prior undergoes a spinal anesthetic for wide local excision of right thigh Merkel cell carcinoma and develops refractory hypotension and subsequent myocardial ischemia.

Authors: Pablo Gavazza, MD; Christine Hollister, MD; Cecilia Canales, MPH; Daniel Chun, MD; Sharon Lin, MD

Date(s) of Development: 5/7/2010

Target Audience (check all that applies):

1. Anesthesiology residents (PGY 2-4)

2. Anesthesiologists in practice

3. Certified registered nurse anesthetists (CRNA)

4. Critical care fellows

5. Medical students (MS4)

Section 2: Curricular Information

Educational Rationale:

Sympathectomy and hypotension are well known complications of a subarachnoid block (SAB). Identification and treatment of these common occurrences are considered basic principles in the use of neuraxial blocks. In a patient with a transplanted heart, the physiology involved can be further complicated as patients are preload-dependent. This scenario exposes participants to the extreme complications of a SAB (hypotension and myocardial ischemia) in a patient with cardiac transplant and to the responses to different treatments.

ACGME Core Competencies

1. Patient care (pc)

2. Medical knowledge (mk)

3. Practice-based learning and improvement (pli)

4. Interpersonal and communication skills (cs)

5. Professionalism (pr)

6. Systems-based practice (sbp)

Learning Objectives

1. Identify sympathectomy as the cause of hypotension immediately following subarachnoid block (pc, mk).

2. Discuss the diagnosis and treatment of myocardial ischemia (pc, mk).

3. Describe the appropriate selection of medications in a cardiac transplant patient experiencing severe refractory intraoperative hypotension (pc, mk).

4. Demonstrate effective communication with operating room staff during crisis and delegate tasks effectively (cs, pli, sbp, pr).

5. List the differential diagnosis of intraoperative hypotension (pc, mk).

6. Describe the physiology of a patient with a transplanted heart and the effect of a subarachnoid block (pc, mk)

7. Describe the preoperative evaluation of a patient with a transplanted heart (pc, mk, sbp).

Simulation Performance Objectives

1. Recognize myocardial ischemia

2. Treat hypotension aggressively, escalating pressors and care quickly

3. Start epinephrine drip

4. Increase FiO2 to 100%

5. Place invasive monitors (A-line, CVP, PA catheter)

6. Intubate patient

7. Call for help

8. Call for TEE, consult cardiology/ cardiac anesthesia

Guided Study Questions:

1. Identify important aspects of the preoperative evaluation of a patient with a cardiac transplant.

2. Describe the cardiac physiology of a cardiac transplant patient.

3. What are some advantages/disadvantages of spinals versus epidurals?

4. What are some advantages/disadvantages of neuraxial blocks versus general anesthesia?

5. How might physical signs or symptoms of myocardial ischemia differ in a patient with a history of a cardiac transplant?

6. What medications are appropriate in the treatment of bradycardia in the cardiac transplant patient?

7. What is Cardiac Allograft Vasculopathy?

References used:

1. D. C. H. Cheng and D. D. Ong: Anaesthesia for non-cardiac surgery in heart-transplanted patients, Canadian Journal of Anasthesia 1994; 41(70): 655-6.

2. Blasco et al: Anaesthesia for noncardiac surgery in the heart transplant recipient: Current Opinion in Anesthesiology 2009; 22:109-113.

3. Allard R: Decreased heart rate and blood pressure in a recent cardiac transplant patient after spinal anesthesia: Can J Anaesth, 2004; 51(8):829-33.

4. Gaba DM, Fish KJ, Howard SK: Crisis Management in Anesthesiology, 1994, pp 98-101.

5. Belikov S, Hoftman N, Mahajan A: Anesthesia for Heart Transplant Patients. Seminars in Anesthesia, Perioperative Medicine and Pain 2004; (23): 22-33.

Section 3: Preparation

Monitors Required:

• Non-invasive BP cuff

• Arterial line

• 5 lead EKG

• Pulse oximeter

• Capnograph

Other Equipment Required:

• Anesthesia machine

• Laryngoscope

• ETT

• LMA

• Pumps

• Defibrillator

• TEE

• Labeled syringes

• Normal saline

Supporting Materials:

• CXR

• 12 Lead ECG

• Preoperative H&P

• Echo

Time Duration

|Set-up |15 minutes |

|Preparation |10 minutes |

|Simulation |15 minutes |

|Debrief |30 minutes |

Section 4: Simulation Exercise

Case Stem to be read to participants:

GH, an 80-year-old male with a history of cardiac transplant 13 years ago, is scheduled for a wide-local excision of a Merkel cell carcinoma of the right thigh and inguinal lymph node dissection. His past medical history includes hypertension, diabetes mellitus type 2, hyperlipidemia, peripheral vascular disease, chronic kidney disease, descending thoracic aneurysm of 4cm, and a 4.5cm abdominal aortic aneurysm. Medications include glargine, cyclosporine, mycophenolate, telmisartan, furosemide, omeprazole, clopidogrel, calcium gluconate, and aspirin. He is allergic to sirolimus.

You are in the outpatient surgery center in the operating room and just placed a spinal in sitting position at L4-L5 with lidocaine 5% 1.5 mL + 7.5% dextrose and fentanyl 25 mcg. The patient develops a T10 level block.

Additional information if asked

• Past Surgical History: Orthotopic heart transplant (OHT) 13 years ago, bilateral knee surgery, multiple basal cell carcinoma excisions, right superficial femoral artery stent 15 years ago.

• No problems with prior general anesthetic

• Exercise tolerance: The patient does not describe physical limitations, but also does not engage in strenuous activity or climb stairs frequently because of residual pain after knee surgery.

• Electrocardiogram: Sinus Tachycardia at 108 beats/min, 1st degree AV block, right bundle branch block, Q-waves in the inferior distribution

• Cardiac catheterization six months ago: Left anterior descending 100% mid vessel occlusion, circumflex 100% occlusion with collaterals, right coronary 100% occlusion, left internal mamillary artery to left anterior descending artery graft is patent, pulmonary artery pressure is 38/26, wedge 25, CO 3.9 L/min

• Echocardiogram 6 months ago: ejection fraction of 50-55%, normal wall thickness, global hypokinesis

Information for Facilitator/Simulator Operator Only

Patient History:

GH, an 80-year-old male with a history of orthotopic heart transplant 13 years ago, hypertension, DM type 2, peripheral vascular disease, chronic renal insufficiency and abdominal aortic aneurysm (4.5 cm) presents for wide-local excision of a Merkel cell carcinoma of the right thigh and inguinal lymph node dissection.

Review of Systems:

CNS: Awake, alert and oriented x 3

Cardiovascular: Heart transplant 13 years ago, exercise tolerance difficult to assess, denies chest pain or shortness of breath

Pulmonary: Negative

Renal / Hepatic: Chronic kidney disease

Endocrine: DM type 2

Heme/ Coag: Negative

Current Medications and Allergies: Glargine, cyclosporine, mycophenolate, telmisartan, furosemide, omeprazole, clopidogrel, calcium gluconate, and aspirin. He is allergic to sirolimus.

Physical Examination:

General: No acute distress

Weight, Height: 180 pounds, 5’10”

Vital Signs: BP 132/84, P 94, RR 16, SaO2 95%

Airway: MP3, neck FROM, TM > 3 FB

Lungs: CTAB

Heart: RRR, no murmurs

Laboratory, Radiology, and other relevant studies:

WBC 6.3, Hgb 16.2, Hct 47.9, Plt 247, Na 139, K 4.5, Cl 107, HCO3 26, BUN 28, Cr 1.8, Glu 102

CXR: WNL

EKG: Sinus Tachycardia rate 108, 1st degree AVB, RBBB, Q waves II, III, avF

|State |Patient Status |Student learning outcomes and trigger to move to next state |

| 0:00 | |Learner Actions: |Operator: |

|BASELINE |Patient is supine and awake |Initial administration of fluids and constant observation of |Patient is awake with |

| |and alert with supplemental |patient |monitored anesthesia care |

| |oxygen | | |

| | | |Teaching Points: |

| |BP 145/95 | |Situation, background, |

| |HR 105 | |assessment, recommendation |

| |RR 12 | |(SBAR) |

| |SaO2 96% | | |

| | | | |

| | | |Trigger: Time (1 min) |

| 1:00 |Patient is calm. The |Learner Actions: |Operator: |

|Mild hypotension begins|treatments will have no |Fluid administration, initial use of phenylephrine versus |Patient becomes hypotensive |

| |hemodynamic effect |ephedrine |with no effect from fluids |

| | | | |

| |BP 93/63 | |Teaching Points: |

| |HR 104 | |Cardiac physiology post OHT; |

| |RR 12 | |recognize refractory |

| |SaO2 95% | |hypotension |

| | | | |

| | | |Trigger: Fluid Administration|

|3:00 |Pt complains of nausea |Learner Actions: |Operator: |

|Hypotension is | |Escalation of pressor support including epinephrine boluses |Patient complains of nausea. |

|refractory to treatment|BP 65/51 | |If pressors are used, |

| |HR 98 | |patient’s vitals improve. |

| |RR 17 | | |

| |SaO2 93% | |Teaching Points: |

| | | |Preload dependence of patient|

| |Initial choice of escalated | |post OHT |

| |pressor mildly improves blood| | |

| |pressure and heart rate | | |

| | | |Trigger: With time patient |

| |BP 83/55 | |continues to deteriorate; |

| |HR 110 | |pressor use mildly improves |

| |RR 19 | |vitals |

| |SaO2 93% | | |

| 5:00 |Patient becomes more |Learner Actions: |Operator: |

|Myocardial ischemia |hypotensive, develops |Recognition of myocardial ischemia. Consider use of |Patient develops myocardial |

|ensues |myocardial ischemia and |epinephrine drip |ischemia |

| |bradycardia | | |

| | | |Teaching Points: |

| |Atropine or glycopyrrolate | |Recognition of myocardial |

| |have no effect | |ischemia |

| | | |Consider epinephrine drip |

| |HR 52 | | |

| |BP 62/49 | |Trigger: Prolonged |

| |RR 16 | |hypotension |

| |SaO2 93% | | |

| |EKG: ST elevations | | |

|7:00 |Patient is unresponsive |Learner Actions: |Operator: |

|Cardiac arrest | |Cardiopulmonary resuscitation with appropriate ACLS treatment|Patient unresponsive, |

| |BP 33/- |of ventricular fibrillation |develops ventricular |

| |HR – |Intubate patient |fibrillation |

| |RR 0 | | |

| |SaO2 not readable | |Teaching Points: |

| |EKG: Ventricular fibrillation| |Review ACLS protocol |

| | | |Call for help, mobilize |

| | | |resources early |

| | | | |

| | | | |

| | | |Trigger: 2 minutes after |

| | | |onset of myocardial ischemia |

|9:00 |Patient is in sinus rhythm |Learner Actions: |Operator: |

|Patient recovering from|with ST elevation, requiring |Continued cardiopulmonary support and decision to end surgery|Patient unconscious but |

|ventricular |hemodynamic support. |and transfer patient to intensive care |improved vitals |

|fibrillation | | | |

| |HR 111 |Call for TEE/ cardiology consult |Teaching Points: |

| |BP 91/62 | |Importance of effective |

| |RR Ventilator |Place invasive monitors |communication with operating |

| |SaO2 100% | |room staff |

| |EKG: Sinus Tachycardia with |Send ABG, labs |Need for invasive monitoring |

| |ST elevations | | |

| | | | |

| | | |Trigger: Appropriate ACLS |

| | | |management |

Section 5: Debriefing & Evaluation

A. Debriefing Key Points and Topics for Discussion

• What is the cause of hypotension in this patient?

• Describe the mechanism that led to the deterioration of this patient’s state?

• Why did you choose your particular pressors when hypotension initially occurred?

• What was the cause of the patient’s nausea and why was there no chest pain involved?

• What is the importance of preload in a patient with a cardiac transplant?

• What medications are appropriate in the cardiopulmonary resuscitation of a patient with cardiac transplant?

• Why do atropine and glycopyrrolate have no effect in this patient?

• Discuss the risks and benefits of a spinal vs. general anesthetic in this patient?

• Is this case appropriate for the outpatient setting?

Discussion points

Spinal Anesthesia and Hypotension

Hypotension is a commonly seen side effect of spinal anesthesia caused by the sympatectomy of the medication used. This causes a decrease in peripheral vascular resistance, venous pooling, and a decrease in preload. If the thoracic T1-T4 cardiac accelerators are involved, there can also be a resultant decrease in heart rate and cardiac output. To avoid severe hypotension, patients are often given a fluid bolus prior to administration of spinal anesthesia.

Spinal VS Epidural Anesthesia

|Spinal |Epidural |

|Intrathecal space |Epidural Space |

|Faster onset |More gradual onset |

|One shot |Catheter in place for redosing or continuous delivery of |

| |medication |

|Technically easier |May be technically more challenging |

Cardiac Physiology Post Orthotopic Heart Transplant (OHT)

• Recipient retains innervated (but hemodynamically insignificant) native atrial cuff

• Donor heart is denervated (both vagal and sympathetic), so intrinsic control is by

o Sino-atrial (SA) node depolarization and impulse conductivity

o Frank-Starling response to preload

o Intact alpha- and beta-adrenoreceptors

• Because the heart transplant recipient has the retained native atrial cuff and the donor atrium, two P waves are often seen on ECG

• Because denervation includes afferent sensory fibers, patients do not experience chest pain with myocardial infarction

• At rest, the heart rate (90-100) reflects the intrinsic depolarization of the SA node in absence of vagal tone

• Unlike the normal heart, which increases cardiac output through neural activation with a resultant increase in heart rate and contractility, the transplanted heart relies on changes in stroke volume by means of the Frank-Starling mechanism. Heart rate increases only after sufficient circulating catecholamines are present.

Common Medication Effects in OHT Recipients

Since the transplanted heart is denervated, direct acting medications are effective

|Response to Medication |No or Limited Response to Medication |

|Epinepherine |Anticholinergics |

|Isoproterenol |Anticholinesterases |

|Dopamine |Muscle Relaxants like Pancuronium |

|Glucagon |Ephedrine |

Because heart is denervated and preload dependent, avoid beta-blockers and use medications like nitroglycerine and sodium nitroprusside with caution.

Cardiac Allograft Vasculopathy

• Accelerated form of coronary artery disease which involves classic and immunologic mechanisms that cause diffuse lesions, which show concentric proliferation of the intima

• Seen in 30-60% of cardiac transplant recipients within 5 years of transplant

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