Cardiac surgery : Optimizing care and management · CVP –central venous pressure 8-12 mmHg PCWP –Pulmonary capillary wedge pressure 15-18 mmHg 50% iv maintenance rate (low Na

Cardiac surgery : Optimizing care and management

Narongrit Kantathut, MD.

Thoracic and Cardiovascular Surgery, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand

Overview

� What is cardiac surgery?

� How to assess the hemodynamic in post-op patient?

� Complications and management

Overview

• Coronary bypass

• Valvular surgery

• Combined

• Aortic surgery

• Congenital heart surgery

• Heart transplant

• Lung transplant

• Heart-lung transplant

Cardiac surgery : Unique characteristics

� Cardiopulmonary bypass (CPB)

� Hypothermia

� Anticoagulation

� Cerebral and end-organ protection

� Myocardial protection

� Ischemic – reperfusion injury

� Cardioplegia

� Complexity of heart structure

� Conducting system

� Heart valve, coronary artery, congenital malformation

Basic Cardiopulmonary bypassFor Critical Care Nursing

Narongrit Kantathut, M.D.

Cardiopulmonary bypass (CPB)

• Most or all of the patient’s systemic blood, which normally returns to the right atrium, is diverted into a device in which oxygen is supplied to the blood and carbon dioxide is removed. The newly arterialized blood is pumped from the device into the aorta.

• Total cardiopulmonary bypass

• Partial cardiopulmonary bypass

Cardiopulmonary bypass (CPB)

• Arterial cannulation

• Venous cannulation

• Venous reservoir

• Tubing circuit

• Oxygenator

• Pump

• Heat exchanger

• Filter and bubble trap

Arterial cannulation

• Ascending Aorta

• Peripheral cannulation

• Femoral artery

• Right common carotid artery

• Right axillary artery

Venous cannulation

• Single venous cannulation

• Bicaval cannulation

• Single “two stage” cannulation (Right atrial)

• Peripheral cannulation (Femoral vein , Rt.IJ )

Venous reservoir

• Gravity or Siphonage

• Vacuum assisted drainage

• 40-70 cm below the level of the Heart

• Priming : isotonic solution

Oxygenator and Heat exchanger

• Membrane oxygenator

• Less gaseous microemboli

• Diffusion of O2 and CO2

Pumps

• Roller pump

Pumps

• Centrifugal pump

Methodology

• Anticoagulation : heparin for 3 min

• Cannulation : Arterial and venous

• Initiation : ACT > 400-480 sec

• Cooling : Hypothermia

• Surgery : aortic cross clamp, cardioplegia , venting

• Rewarming

• Weaning CPB

• Reverse anticoagulation

• Decannulation

Hypothermia

• 10 °C change � VO2 decrease by 50%

• Heart, Brain and kidney protection, less blood trauma

• Increase “safe period” of CPB

Hypothermia• Flow-temperature relation

• Mild 30-35 °C

• Moderate 25-30

• Deep 18-25 °C

• Deep hypothermic circulatory arrest

Heparin

• Anticoagulation

• 300-400 U/kg (3-4 mg/kg)

• ACT (Activated Clotting Time)

• > 400-480 sec

• Kaolin , Celite

• Antithrombin III (May need ATIII or FFP to archive ACT level)

Heparin

• Heparin-induced Thrombocytopenia and Thrombosis (HIT and HITT)

• 5-15 days

• PF4 (Platelet Factor 4 IgG) for Diagnosis

• Postpone for > 100 d and recheck

• Bivalirudin or Argatroban

Protamine

• 1-1.3 mg/100 U of Heparin to normalize ACT

• Hypotension and Anaphylactic reaction

• IgE mediated , Histamine and vasoactive mediators

• Hypotension , bronchospasm

• Pulmonary vasoconstriction , pulmonary hypertension

• IgG release , compliment activation , PMN and platelet TXA2

• Previous vasectomy , exposure to protamine or protamine-contain insulin

Effect of CPB

• circulate through nonendothelially lined channels

• contain gaseous and particulate emboli

• experience nonphysiologic shear stresses

Effect of CPB

• Inflammatory response

• Increase vascular permeability

• Humoral , compliment and cellular activation

• Renal and pulmonary dysfunction

• Platelet dysfunction

• Neurohormonal response

• Stress

Effect of CPB

• Hemodilution

• Edema

• Bleeding

• Hemolysis

• Organ dysfunction : Brain , kidney , lungs

• Hypothermia

• Air embolism

Precaution

• Bleeding : trauma , Stroke , recent surgery , Hematologic disorders

• Organ dysfunction : brain , kidney , lungs , liver

• Active infection

• HITT

• Religion : Jehovah's Witnesses

Basic Myocardial ProtectionFor Critical Care Nursing

Narongrit Kantathut, M.D.

Myocardial Protection

� To stop the heart without or less injury

� Decreasing myocardial oxygen demand – Hypothermia

� Use of electromechanical cardiac arrest - Cardioplegia

Myocardial injury

� Ischemic/reperfusion injury

� Reversible (viable)

� Stunning – normal blood supply, reduced function

� Hibernating – reduced blood supply, reduced function

� Chronic stable angina, Acute MI

� Irreversible

� Infarction

� Low Cardiac Output Syndrome (LCOS)

� Increased mortality and complications

� Increased ICU stay and hospital stay

Low Cardiac Output Syndrome

� Definition� Cardiac index < 2.0-2.2 L/min/mm2 and

� systolic blood pressure < 90 mmHg

� poor tissue perfusion (cold periphery, clammy skin, confusion, oliguria, elevated lactate level)

� without hypovolemia

Hemodynamic management

� BP drop ????

� O2 Sat drop ????

ตวัชี�วดั

� �� = SET index

� ��ก� GDP

� ��

� BMI

� KPI key performance index


� Goal of cardiovascular system = Adequate Oxygen Delivery

� O2 delivery = CO x CaO2

� CO = Cardiac output

� CaO2 = Arterial O2 content

= O2 Hb + O2 dissolved in arterial blood

= (Hb × %sat)(1.34) + (PaO2)(0.0031)


� Fick principal

Cardiac output = VO2/A-V O2 difference

• A-V O2 Difference = (1.34)(Hb) × (SaO2 – SvO2)

• Estimated VO2 (Oxygen comsumption) = 125 x BSA

• SvO2 = O2 sat in mixed venous blood

• SVC

• IVC

• Coronary sinus


� Cardiac Output = 4 – 8 L/min

� Cardiac index

� CO/BSA = 2.2-4.0 L/min/m2

� Cardiac output = Stroke volume x Heart rate

� Cardiac output = 80 x (MAP – CVP)/SVR

SVR = Systemic vascular resistance

= 800-1200 dyn-s/cm5

MAP = Mean arterial pressure

CVP = Central venous pressure

BSA = Body surface area


� Cardiac output = Stroke volume x Heart rate

� CO = SV x HR

� Stroke volume

� SV = LVEDV - LVESV

� EF = SV/EDV x 100%

� Preload

� Afterload

� Contractility

CO = LVEDV x EF x HR / 100%

LVEDV = Left ventricular end diastolic volume

LVESV = Left ventricular end systolic volume


Cardiac output ?

Cardiac Index ?

Preload ?

Afterload ?

Contractility ?

LVEDP , LVESV

EF?

Stroke volume ?

SVR ?


� Pulmonary artery catheter (Swan-Ganz catheter)


� Pulmonary artery catheter


� Pulmonary artery catheter

� Mixed venous blood (MvO2) – distal port

� Cardiac output/index

� Thermodilution

� Fick principal

� Systemic vascular resistance (SVR)

� Pulmonary capillary wedge pressure (PCWP)

� LV preload

� PA diastolic pressure

� Central venous pressure (RAp, CVP)


� Fick principal

Cardiac output = VO2/A-V O2 difference

• A-V O2 Difference = (1.34)(Hb) × (SaO2 – SvO2)

• Estimated VO2 (Oxygen comsumption) = 125 x BSA

• SvO2 = O2 sat in mixed venous blood

• SVC

• IVC

• Coronary sinus


� Preload

� “Frank – Starling Law”

� CVP – central venous pressure

� 8-12 mmHg

� PCWP – Pulmonary capillary wedge pressure

� 15-18 mmHg

� 50% iv maintenance rate (low Na solution, 5%DN/2, 5%DN/5 or 5% DW)

� Resuscitation with Colloid vs Crystalloid – no difference

� Red cell transfusion

� Hb level 7-10 � adequate O2 delivery

• Frank – Starling mechanism

• Increase preload � increase

stroke volume


� Afterload – wall stress

� SVR – Systemic vascular resistance

� High BP – reduced EF , increase O2 demand

� Too low – decrease coronary blood flow , decrease O2 supply

� Afterload reduction

� Increase EF, increase O2 supply, decrease O2 demand

� Nitroglycerin

� Nitroprusside

� Vasopressor

� Low SVR syndrome – effect of CPB, inflammatory response

� Normal CI , low BP (periphery)

� Norepinephrine , vasopressin


� Contractility

� EF – Ejection fraction = (EDV – ESV)/EDV x 100%

� Echocardiography

� Most of cardiac procedures have some degree of myocardial injury

� Inotropic drug

� Dopamine

� Dubutamine

� Epinephrine

� Milrinone


� Heart rate

� Heart block, Junctional rhythm, Bradycardia

� Cause by ischemia, direct injury to conducting system

� 90-110 /min

� Pacing wires

� Ventricular pacing

� Atrial pacing

� AV - pacing


Cardiac output ?

Cardiac Index ?

Preload ?

Afterload ?

Contractility ?

LVEDP , LVESV

EF?

Stroke volume ?

SVR ?

Mechanical circulatory support

� Intra-aortic balloon pump (IABP)

� Augment coronary blood flow – diastolic inflation

� Reduce afterload – systolic deflation

� ECMO

� Ventricular assist device

� LVAD , RVAD

� Heart transplant

IABP – Intra-aortic balloon pump

counterpulsation

Common complications in cardiac surgery

� Low cardiac output syndrome

� Bleeding

� Arrhythmia : post-op atrial fibrillation

� Sternal wound infection

� Graft site infection

� Neurologic complication : Stroke

� Renal complication : Acute renal failure

� Pulmonary complication



� Bleeding







Postoperative bleeding

� Risk factors

� Pre-op antiplatelet , anticoagulation

� Intra-op heparinization

� Procedural complexity

� Platelet dysfunction (CPB and hypothermia)

� Re-exploration rate 5%


� 200 cc/hr of chest tube output requires immediate attention

� Medical vs. Surgical bleeding

� Routine care

� Rewarming to normothermia

� Check coagulogram, ACT, fibrinogen level

� Milk chest drains to prevent occlusion and cardiac tamponade

� Optimize volume

� Red cell transfusion if Hb < 7 mg/dL


� Medical bleeding

� Protamine 25-50 mg

� for prolong ACT (100-120 sec)

� Heparin rebound

� Platelet

� FFP – prolong aPTT, PT

� Cryoprecipitate – low fibrinogen level

� Pharmacological treatment

� Tranexamic acide (TXA, transamine)

� Recombinant activated factor VII


� Surgical bleeding

� Unstable hemodynamic with normal coagulogram

� Off and on re-bleeding

� Require emergency exploration

� ICU

� OR



� Bleeding







Postoperative atrial fibrillation/flutter

Postoperative atrial fibrillation/flutter

� Most common arrhythmia, Incidence 30-50%

� Increased hospital stay and stroke

� Risk factors : Older age, E’lyte imbalance, prolong cross clamp time, COPD,

discontinue beta-blocker

� Atrial fibrillation

� Loss of AV synchrony,

� decreased EF 20-30%

� Blood stasis

� increased embolic complication

Postoperative atrial fibrillation

� Principal of treatment

� Rate control

� Rhythm control

� Prevention of embolic complications

� Stable vs Unstable

� Avoid multidrug therapy � Heart block, sinus arrest


� Unstable patient

� Rapid ventricular response

� Hemodynamic instability

� Cardioversion 120-200 J


� Stable patient

� Rate control

� Calcium channel blocker (diltiazem, verapamil), cautious in CHF and low EF

� Short acting beta-blocker (Metoprolol, esmolol)

� Digitalis – less effective

� Rhythm control

� Amiodarone

� 5-7 mg/kg iv bolus then 1.2 -1.8 g/day iv maintenance

� or 10 g of total oral dose then 200-400 mg/d maintenance

� Precautious in severe sinus node dysfunction, advanced conduction disease, severe pulmonary disease


� Failure in conversion to sinus rhythm

� If > 48 hrs , need therapeutic anticoagulation

� Heparin , aPTT 2 times (50-70 sec)

� Warfarin, INR 2-3 times

� Low molecular weight heparin (LMWH)

� May consider cardioversion with trans-esophageal echocardiography

� TEE - cardioversion

� r/o clot in left atrial appendage



� Bleeding







Sternal wound complication


� Sternal dehiscence


� Superficial

� Deep


� Sternal dehiscence

� No evidence of infection (Clinical and Microbiological)

� Osteoporosis, severe cough, obesity

� Improper surgical technique

� Non-middle sternotomy

� Over traction from sternal retractor

� Stability – palpate the sternum on both sides, let patient breath and cough

� Paradoxical movement – unstable � need emergency surgery

� Stepping

� Difficulty breathing

Sternal wound infection


� Superficial

� Limit to subcutaneous tissue

� Wound dressing + Antibiotics

� Deep

� Sternal osteomyelitis, retrosternal space, mediastinitis

� chest pain, sternal instability or fever (>38°C) with purulent discharge from mediastinum


� Deep sternal wound infection

� Risk factors

� Pre-op : obesity, DM, COPD, renal failure, poor dental hygiene, prolong hospital stay smoking

� Intra-op : improper prophylactic antibiotics, uncontrolled blood sugar, use of bilateral IMA, redo surgery, excessive bone wax

� Post-op : re-exploration for bleeding, prolong intubation, blood transfusion

� Pathogen� Most common : Staphylococcus aureus and coagulase-negative staphylococci

� Gram negative bacteria - Prolong ICU stay ,pneumonia, urinary tract infection, abdominal sepsis


� Deep sternal wound infection

� Admission for iv antibiotics

� Blood and wound culture

� CXR and CT chest

� Echocardiography in patient with prosthesis valve

� r/o infective endocarditis

� Treatment

� Intubation, ICU

� Surgical debridement, Vacuum dressing, delay closure

� Rigid plate fixation with flap coverage (pectoralis major flap, rectus abdominis flap, omental flap)



� Bleeding







Graft site infection

� Saphenous vein graft site, incidence 3-4%

� endoscopic venous harvesting – lower incidence

� Staphylococcus aureus – most common

� Pseudomonas, gram-negative bacteria in prolong ICU stay and broad spectrum ATB

� Treatment

� Surgical debridement + ATB



� Bleeding







Stroke

� Incidence 1-2%

� Awake within 1-2 hrs post-op, if not or neurodeficit, r/o stroke

� Risk factors : � Older age, Previous stroke, female, DM, Hypertension, Atherosclerosis of ascending aorta

� Etiology

� Particle and gas from CPB

� Macro-emboli from manipulation of aorta or neck vessel

� Regional malperfusion – stenotic cebebral vessel

� Generalize hypoperfusion (watershed infarction) from CPB

� Impaired cerebral autoregulation (DM)

� Generalize central nervous edema from CPB

Stroke

� Adequate brain perfusion and oxygen delivery

� Improve cerebral perfusion

� Elevated head

� Hyperventilation – moderate hypocapnia to reduce brain edema

� Intubation and prevent aspiration

� Mild Hypertension

� Neurology consult, CT brain

� Most patients will be improved within 24 hrs

� May need intervention if < 6 hrs period

Delirium

� Without neurodeficit, 3-72%

� Increased complications and mortality

� Prevention

� Early ambulation

� Frequent communication with patient : time, place, person

� Family visit

� Avoid anticholinergic, benzodiazepine and GABA agonist

� Rx : haloperidol, novel anti-psychotic



� Bleeding







Acute renal failure

� Incidence 7.7%, and 1.4% need hemodialysis

� Rising BUN, Cr, decrease urine output (0.5-1 cc/kg/hr)

� Increase mortality, complications, ICU and hospital stay

� Risk factors

� Reduced kidney function, Older age, CHF, DM

� Causes

� Non-pulsatile flow from CPB

� Atheromatous emboli

� Inflammatory response

Acute renal failure

� Optimizing volume, diuretic

� Indication for renal replacement therapy

� severe refractory acidemia (pH <7.2) or persistent intractable alkalemia (pH >7.6)

� hyponatremia (sodium <125 mEq/L)

� hyperkalemia (potassium >6 mEq/L)

� complicating oliguria

� severe azotemia (BUN >100 mg/dL)

� rapidly progressive azotemia (BUN >20 mg/dL daily increment)

� intractable fluid overload

Acute renal failure

� Conventional vs CVVHD

� Continuous venovenous hemodialysis (CVVHD)

� unstable, critically ill

� Conventional hemodialysis

� Stable patient

� Early initiation of renal replacement therapy

� Decrease mortality and ICU stay



� Bleeding







Pulmonary complication

� Mild pulmonary dysfunction 12%, usually return to normal

� Extubation within 24 hrs in most patients

� ARDS 1.3% � > 50% mortality

� Risk factors� Older age, obesity, low cardiac output, pulmonary hypertension, prolonged

cardiopulmonary bypass, emergency surgery, Stroke

� Increase mortality, ICU and hospital stay, complications

� Nosocomial infection

� Prolong mechanical ventilation


� Supportive treatment� PEEP (Positive end-expiratory pressure) to improve oxygenation

� Proper ATB management in pulmonary infection

� Respiratory care : secretion clearance and prevent aspiration

� Intubation > 2 weeks � tracheostomy


� VAP (ventilator-associated pneumonia)

� Prolong intubation > 48 hrs

� Increase mortality

� Prevention

� Head elevation

� Proper sedation and daily evaluation for extubation

� Peptic ulcer disease prophylaxis

� Deep vein thrombosis prophylaxis

Aggressive control of blood sugar

� All post-op patient have hyperglycemia

� Reduced mortality and complications

� < 180-200 mg%, depends on hospital protocol

� Requires iv insulin

� Check blood sugar q 1-2 hrs

� Hypoglycemia

Conclusions

� Open heart surgery

� CPB

� Myocardial protection

� Hemodynamic assessment and management

� Complications and management

Documents

Cardiac surgery : Optimizing care and management · CVP –central venous pressure 8-12 mmHg PCWP –Pulmonary capillary wedge pressure 15-18 mmHg 50% iv maintenance rate (low Na