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Perioperative Care of the Cardiac Surgery Patient

Lars Hegnell, MD

Michael Hutchens, MD, MA

Matthew Griffee, MD

Cardiac, Thoracic, and Surgical ICU,

Department of Anesthesiology and Perioperative Medicine

Oregon Health & Science University,

Portland, Oregon

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Learning Objectives

• Understand risk factors for perioperative morbidity and mortality among adult cardiac surgery patients.

• Identify common perioperative complications

• Integrate scientific evidence and consensus guidelines into strategies for risk reduction and for treating post-operative complications

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Goals of Preoperative Evaluation

• Identify post-operative risk for resource allocation (e.g.,1:1 nursing assignment, IABP)

• Counsel patient and family about ICU environment and expected course

• Modify risk factors for medical optimization (smoking, lipid control, control of HTN)

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Risk Prediction Tool-EUROSCORE

• European System for Cardiac Operative Risk Evaluation• www.euroSCORE.org

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Euroscore Risk Calculation

• Patient Related Factors

– Age, gender, chronic disease (e.g., COPD, stroke)

• Cardiac Factors:

– 1. Unstable angina

– 2. Recent MI

– 3. Decreased LV function

– 4. Pulmonary Hyptertension

• Operative Factors: Emergency, complex, aortic surgeryEur J Cardiothorac Surg 1999 Jun;15(6):816-22; discussion 822-3 

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Pre-op cardiogenic shock

• Invasive monitoring and inotropic support

• Diuretics, in case of pulmonary edema

• Consider intubation and mech. ventilation

• Echo/cath lab determination of severity of LV dysfunction

• Multidisciplinary discussion of timing of surgery, potential consults: heart failure/transplant, CT surgery, interventional cardiology, referral center

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Pre-Op Cardiogenic Shock and Very High Risk Patients

• Intra-Aortic Balloon Pump Pre-Op placement in high risk patients (recent MI, EF<30%, severe CAD) associated with reduced mortality (OR 0.41, 95% CI 0.2-0.8, p=0.01)

• 4% risk of complication; risks include aortic dissection, limb or visceral ischemia

• Discuss delay of OR for optimization with teamMeta-analysis: Dyub AM, Whitlock RP, J Cardiac Surg 2008; 23: 79-86

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Multisystem Adverse Effects of Cardiopulmonary Bypass

• BYPASS CAUSES SIRS, wide range of severity

• Coagulopathy, platelet dysfunction, fibrinolysis

• Vasodilatation resembling septic shock, with high levels of nitric oxide

• Acute kidney injury (especially in case of chronic kidney disease)

• Neurocognitive deficits

• Hypothermia

• Acute Lung Injury

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Approach to immediate post-op cardiac surgery patient

• COMMUNICATION

• Discuss procedure and anticipated issues with surgeon and anesthesiologist:

• Was pt completely revascularized?

• Evidence of post-bypass coagulopathy?

• TEE results: LV performance and volume status

• Is conduction system impaired?

• Did pt require cardioversion?

• Important bolus medications sometimes overlooked: Amiodarone, milrinone, furosemide, mannitol, paralytic

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Approach to immediate post-op cardiac surgery patient

• Checklist Items

• Baseline volume in chest drain

• Peripheral pulses, especially for sites with arterial lines

• CXR: PA catheter, ETT, gastric access

• ABG

• Temperature

• Vasoactive infusions

• Hemodynamics

• Initial coagulation panel and other labs

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Hemodynamic Goals

• Cardiac Index >2.2 (convention, acceptable range for individual pt based on organ function, pre-op status)

• SvO2 over 65.

• SvO2 expected to fall with extubation, mobilizaiton, shivering, agitation

• Warm extremities and urine output >0.5ml/kg/hr

• Maintain MAP>60 but SBP<120 (to reduce risk of hemorrhage from aortotomy sites

• Higher MAP necessary in older pts, HTN pts

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Early-Onset Hemodynamic Instability

Common Uncommon

HYPOVOLEMIA Severe mitral regurgitation

Low systemic vascular resistance

Other acute valvular pathology

LV systolic or diastolic dysfunction

Dynamic LVOT obstruction

RV dysfunction/pulm HTN Lung hyperinflation

Tamponade Tension pneumothorax

Patient-Ventilator Dysynchrony/Pain/Agitation

Massive hemothorax

Arrhythmia/Pacer malfunction/poor timing

Cardiothoracic Critical Care, D. Sidebotham, Elsevier, 2007, chapter 20.

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Initial Resuscitation Strategy based on most likely etiology

• Fluid challenge

• Pattern recognition of hemodynamic data (subsequent slide)

• Examine chest tubes, CXR, serial hematocrit levels for evidence of bleeding

• Work through components of cardiac output: Preload, afterload, inotropic state, rhythm, return of blood to R heart

• If persisent difficulty, obtain a stat echo

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Ongoing shock, Unclear cause

• Stepwise optimization of preload, inotropic support, afterload, rate, electrolytes, analgesia, oxygenation.

• Obtain an echocardiogram (TEE if TTE inadequate)

• Obtain a CXR, eval for PTX, hemothorax, widening mediastinum, increasing distance between swan in RA and border of heart (signs of tamponade)

• Increase inotropic support; check ionized calcium

• Consider increasing pacer rate to 90-100 in case intrinsic rate is lower

• Communicate with surgeon

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Case Study 1

The following are case studies that can be used for review of this presentation.

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65 YOM with low BP after re-do CABG

• You are called to the bedside to assess decreasing blood pressure despite increase in phenylephrine, 60 minutes after transfer from OR to ICU.

• Vital signs: pulse 110, sinus, BP 85/60, SpO2 98% on 0.5 FiO2, PEEP 5, Vt 8ml/kg

• Initial 30 min 300ml in chest tube, second half hour 20ml in chest tube

• Breath sounds symmetric, pedal pulses weak but palpable

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65 YOM after re-do CABG

• Bypass time 119 minutes

• Hemodynamics: CI 2.1, PAP 26/17, CVP 19

• Gtts: Phenylephrine 2mcg/kg/min, Vasopressin 1U/hr, Epi 0.02mcg/kg/min

• Report from OR: good revascularization, LVH, looked dry and received 3L crystalloid, 1 L albumin with transient improvement in CI

• Coags: PTT slightly elevated, platelets 110,000, fibrinogen 200, heparin level undetectable

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Re-do sternotomy, low BP

• 1. Does hemodynamic profile suggest vasoplegia (distributive shock) as primary problem?

• 2. What further diagnostic maneuvers will you perform?

• 3. Will you change pressors? If so, how?

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Hemodynamic Patterns

Shock State CVP CO/CI PAP PAWP

Hypovolemia ↓ ↓ ↓ ↓

Vasoplegia/Distributive

↓ or normal INCREASED Low or normal Low or normal

Chronic LV dysfunction

↑ or normal ↓ ↑ or normal ↑ or normal

Acute LV systolic failure

Variable ↓ ↑↑ ↑↑

LV diastolic dysfunction

Normal or ↑ Normal or ↓ ↑ ↑↑

RV Failure ↑↑ ↓ Variable Variable

Our patient has LOW cardiac output, not INCREASED.

Cardiothoracic Critical Care, D. Sidebotham, 2007 Elsevier

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Diagnostic Tests

• 12-lead EKG: no evidence of ischemia

• CXR- cardiomegaly, also seen post-operative

• Fluid challenge: transient increase in cardiac output, then CI decreases to 1.8

• Chest tube output 5ml in next 40 minutes

• Pressor changes??

• Most logical step: increase Epi, repeat fluid challenge

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Conclusion

• Hct repeated. Unexplained drop from 27 to 19, Same on repeat.

• Echocardiogram:

• LV hyperdynamic, RV collapses at end diastole, RA collapses during systole. Pericardial space with anterior fluid collection, distorting RA, RV shape.

• Diagnosis: Tamponade, occluded drains, obstructive and hypvolemic shock. -> to OR

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Post-Bypass Hemorrhage: Tips

• 1. When examining a patient with suspected coagulopathy/ongoing mediastinal bleeding, ensure drains are patent; strip drains periodically

• 2. The most likely lesion of hemostasis after bypass is platelet dysfunction. Platelets are the most rational empiric treatment of post-bypass bleeding especially after long bypass/complex cases

• 3. Rule out persistent heparin with a heparin level or coag tests performed with heparinase.

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Peculiar Complications of Bypass

• Air bubbles inadvertently left in the LV at end of bypass preferentially travel to the right coronary (non-dependent position); the emboli cause acute RV ischemia/acute RV failure.

• Keys to treatment:

– Recognition of acute RV failure (Echo best test)

– Avoiding high airway pressure

– Avoiding hypercapnia, acidosis, and hypoxemia

– Milrinone is pressor of choice Circulation. 2008; 117:1717-1731

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Special Problems After Bypass

• Profound vasodilatation causing distributive shock refractory to vasoconstrictors, “vasoplegia”.

– Consider steroids in moderate doses* X 24-48 hours

– High-dose vasopressin X 12-24 hours

– Several reports and some animal models support rescue therapy with methylene blue

• Ref: Eur J Cardiothorac Surg 2005 Nov; 28(5): 705-10

*240mg hycrocortisone/day after 100mg hydrocortisone bolus. See Crit Care Med 2009;37:1685-90

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Glucose Control in Cardiac Surgery

• Evidence stronger for intensive glucose control in cardiac surgery compared to MICU population

• Aggressive control of blood glucose reduces sternal wound rates

• Anticipate increased insulin needs with patients on epinephrine

• Increased needs when steroids are used

• Concerning increased CVA risk with intensive insulin therapy in one RCT of intensive control

Ann Int Med 2007 Feb 20; 146(4): 233-43

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Post-Op Atrial Fibrillation: Prevention

• Increases morbidity, cost, length of stay

• Common, 30-50% of pts in post-op period

• Amiodarone effective in prevention, yet 25% of pts have side effects, ranging from bradycardia to pulmonary or hepatic toxicity that can be rapidly lethal

• ACC/AHA/ESC guideline: Beta blockers IA, amiodarone IIA, sotalol IIB for prophylaxis

• J Int Care Med 24(1) pp. 18-25, 2009

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Treatment of A-fib: Overview

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Atrial fibrillation: Unstable Patient

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Case Study 2

The following are case studies that can be used for review of this presentation.

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™Slide 31

Tachycardia after AoVR for AS

• 77 YOF with a history of calcification of aortic valve and slowly developing critical Aortic Stenosis undergoes single vessel CABG and Aortic Valve Replacement.

• Salient facts include prominent LVH, including septal hypertrophy and MR. There is systolic anterior motion of the anterior mitral leaflet.

• After extubation, the pt coughs violently. Her BP then drops to 77/40 with a pulse in 160s- the QRS compex is narrow.

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Treatment Options?

• How will you treat the hypotension?

• Will you re-intubate the patient ASAP?

• Suppose cardioversion is successful in restoring sinus rhythm.

• If the BP remains low after a fluid challenge, what is your vasoactive medication of choice?

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Dynamic LV outflow tract obstruction

• Patient is unstable and immediate cardioversion is indicated.

• Intubation and positive pressure ventilation may exacerbate the SAM/outflow obstruction

• Phenylephrine and maintaining LV filling addresses the physiology: Maintain afterload, avoid hyperdynamic LV function, and avoid end-systolic obstruction of LVOT

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LV to LVOT Gradient

Copywright 2009 UpToDate; Version 17.1: Patho-physiology of Obstructive Hypertrophic Cardio-myopathy, Author McKenna WJ

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Hypertrophic Cardiomyopathy

• Hypertrophied septum approaches anterior mitral valve at end-systole

• Gradient develops between LV cavity and LVOT

• Gradient worsens and LVOT can become obstructed with empty LV and hyperdynamism of LV (pain, stress, epinephrine, dobutamine, dopamine)

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Blood Conservation in Cardiac Surgery

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Blood Conservation Key Pointsrelevant to ICU providers

• Class I recommendations:

• Preop identification of high-risk patients

• A “multimodal approach involving multiple stakeholders and enforceable transfusion algorithms supplemented with point-of-care testing”

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Example Algorithm for Blood Conservation

• Agreement among ICU, surgeons, anesthesiologists for transfusion trigger Hct

• Treating coagulopathy based on labs and targeting specific hemostatic defect, when possible

• Limiting phlebotomy and using pediatric test tubes

• Uniform dosing of aminocaproic acid

• Pocket cards with algorithm for all providers

• Communication

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Heparin-Induced Thrombocytopenia

• Life-threatening prothrombotic disorder after heparin exposure.

• 25-50% of cardiac surgery pts develop heparin-dependent antibodies;

• 1-3% develop HIT

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HIT in Cardiac Surgery

• A non-heparin anticoagulant is indicated

• Options include argatroban and lepirudin

• Hematology consultation recommended for suspected cases

• LMWH recommended for post-op prophylaxis over UFH, lower-associated incidence of HIT

CHEST supplement 133(6), p. 384, 2008

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Self Assessment

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References

• 1. Nashef SA, Roques F, Hammill BG, Peterson ED, Michel P, Grover FL, Wyse RK, Ferguson TB.  Validation of European System for Cardiac Operative Risk Evaluation (EuroSCORE) in North American cardiac surgery. Eur J Cardiothorac Surg. 2002 Jul;22(1):101-5.

• 2. Roques F, Nashef SA, Michel P, Gauducheau E, de Vincentiis C, Baudet E, Cortina J, David M, Faichney A, Gabrielle F, Gams E, Harjula A, Jones MT, Pintor PP, Salamon R, Thulin L. Risk factors and outcome in European cardiac surgery: analysis of the EuroSCORE multinational database of 19030 patients. Eur J Cardiothorac Surg. 1999 Jun;15(6):816-22; discussion 822-3.

• 3. Dyub AM, Whitlock RP, Abouzahr LL. Preoperative intra-aortic balloon pump in patients undergoing coronary bypass grafting. J Card Surg 2008; 23: 79-86.

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References

• 4. Cardiothoracic Critical Care. Sidebotham D, McKee A, Gillham M, Levy JH. Elsevier, Philadelphia, PA, 2007.

• 5. Khoo WC, Lip GY. Acute management of atrial fibrillation. Chest 2009; 135: 849-859.

• 6. Society of Thoracic Surgeons Blood Conservation Guideline Task Force. Perioperative blood transfusion and blood conservation in cardiac surgery. Ann Thorac Surg 2007; 83: 527-86

• 7. Antithrombotic and Throbolytic Therapy: ACCP Evidence-Based Clinical Practice Guidelines (8th ed). Chest 2008; 133(6): 381S-453S.

• 8. Haddad F, Doyle R, Murphy DJ, Hunt SA. Right ventricular function in cardiovascular disease. Circulation. 2008;117: 1717-1731.

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References

• 9. Weis F, Beiras-Fernandez A, Schelling G. Stress doses of hydrocortisone in high-risk patients undergoing cardiac surgery. Crit Care Med 2009; 37: 1685-1690.

• 10. Shanmugam G. Review- the role of methylene blue in vasoplegic syndrome. Eur J Cardiothorac Surg 2005 Nov; 28(5): 705-10

• 11. Gandhi GY, Nuttall GA, Abel MD. Intensive intraoperative insulin therapy versus conventional glucose management in cardiac surgery. Ann Int Med 2007 Feb 20; 146(4): 233-43