ECMO for Severe Cardiac and Respiratory Failure in Adults Ann Petlin, RN, MSN, CCRC-CSC, CCNS, PCCN Clinical Nurse Specialist, Cardiothoracic Surgery Barnes-Jewish Hospital, St. Louis, MO 63110 March 2016

Objectives Describe the medical indications for the use of extracorporeal membrane oxygenation (ECMO) Differentiate between V-V and V-A ECMO Explain how ECMO works to promote gas exchange Discuss the nursing implications and care of the patient on ECMO

The heart-lung machine first used at the Mayo Clinic in March 1955. Where ECMO came from The heart-lung machine first used at the Mayo Clinic in March 1955. The screen oxygenator is the rectangular box on the top of the machine.

What is ECMO Pump and oxygenator Supports cardiac and/or respiratory function Days to weeks Extended use of cardiopulmonary bypass outside the OR

Indications for Adult ECMO Lung and/or heart disease that is Acute Life-threatening Potentially reversible Unresponsive to conventional therapy Cardiomyopathy, cardiogenic shock, post-cardiotomy Severe ARDS, pneumonia, bridge to transplant Patient has no contraindications to anticoagulation

Conventional heart support in shock Oxygen, pain relief, rest, fluid balance optimal Inotropic medications, vasodilators, Ca+2 blockers Temporary pacing to optimize heart rate, IABP Optimize acid-base and electrolyte balance Address inadequate tissue metabolism

Conventional lung support in ARDS Mechanical ventilation with PEEP 10-15 cm Low tidal volumes with permissive hypercapnea Adequate FiO2 (< 60%); avoid oxygen toxicity Monitor peak and plateau inflation pressures Advanced ventilator modes to increase alveolar recruitment (PC, APRV, Inverse I:E) Prone position Optimize fluids, pulmonary vasodilators

Contraindications / Exclusions Absolute Acute cerebral damage Uncontrolled sepsis Metastatic cancer or other terminal disease Relative (may improve with improved flow) Acute renal failure Liver failure Older age Others: uncontrolled bleeding, aortic insufficiency, little salvageable myocardium, pulmonary HTN

ECMO System Vascular access Centrifugal pump V-A or V-V Centrifugal pump CentriMag at BJH Flow 2 – 6 L/min Membrane oxygenator with integral heat exchanger Heater keeps blood at 37o C for optimal combining of O2 with Hgb Oxygen / air blender / analyzer System fits on portable cart Pump Membrane oxygenator Vascular access Air- O2 blender

Cannulation Inflow = flow of blood from the pt to the device Outflow = flow of blood from the device to the pt Cannula technique depends on: Type of support needed Patient size Clinical situation

Cannulation Closed chest – peripheral vessels access One cannula for inflow; another for outflow

Cannulation Closed chest – peripheral access Dual-lumen access cannula (Maquet Avalon Elite) Link to You Tube video clip: “Maquet Avalon Elite Catheter” (non-USA version)

Dual Lumen Rt IJ catheter

Cannulation Open chest – Cannulas exit near sternum or below ribs; Sternum may be open or closed

Pump to Provide Flow Console & Monitor Pump Motor

Centrifugal Pump Magnet in motor spins pump head Centrifugal forces propel blood Tornado or vortex effect Pressure low in apex of pump; creates vacuum; removes blood from patient Pressure positive at sides and bottom of pump; returns blood to the patient Preload dependent – adequate blood volume Afterload sensitive – blood pressure management

Oxygenator Gas exchange device Adds O2, removes CO2 Driven by gradients (high pressure to low) Surface area = 1.8 M2 Blood access in/out Gas inlet Heat exchanger

Surface area for gas exchange Adult lung vs. ECMO oxygenator Adult lung surface area ~ 75 M2 ECMO Membrane ECMO Membrane = 1.8 M2

ECMO Principle ECMO works by diffusion of gases (O2, CO2) across a semi-permeable membrane Typically the patient remains on a ventilator to help minimize alveolar atelectasis Occasionally patients are extubated while on ECMO Blood side Membrane Gas side

ECMO Gas Exchange Oxygen diffuses into the blood Oxygen concentration higher on gas side of membrane Net diffusion of O2 into the blood FiO2 adjusted to keep O2 sat ~ 95% Carbon dioxide diffuses out of the blood Liter flow of the Air-O2 mixture Speed of the gas in liters/minute determines how quickly CO2 is “swept” out of the blood Net diffusion of CO2 out of the blood Liter flow adjusted to keep PaCO2 within normal (35-45)

CentriMag Consoles 2nd generation CentriMag 1st generation CentriMag

Maquet ECMO Membrane Dark, de-oxygenated blood (right) ; Oxygenated blood (left)

ECMO Membrane & Pump

ECMO Heaters

Gas flow meters, O2 blender and O2 monitor Flow meter – verify gas is flowing (meter set above 0) Flow meters control the gas flow rate (speed of the gas). The O2 blender controls the oxygen concentration delivered to the oxygenator. Mini Ox – monitors delivered O2 % Blender – verify FiO2 is set at prescribed %

Portable ECMO Cart

Extracorporeal Membrane Oxygenation V-V ECMO Respiratory failure unresponsive to conventional management V-V ECMO provides mainly lung support Venous exit cannula from a major vein Venous return cannula to a major vein Variety of cannula options Decreases pulmonary resistance Standard ventilator management Problem: Allows oxygenated blood to recirculate through ECMO circuit Some patients may need a switch to V-A ECMO

Extracorporeal Membrane Oxygenation V-A ECMO Combined cardiopulmonary failure V-A ECMO supports both heart and lungs Venous cannula removes blood from vena cava Rt internal jugular Femoral vein Common iliac Arterial cannula returns blood to central circulation Aorta Femoral artery Variety of cannula options Higher oxygenation possible than with V-V ECMO Problem: Higher risk of systemic emboli Reduces blood flow through the coronary arteries; might need IABP to provide flow to coronaries

V-A ECMO Cannulation Options Central cannulation Femoral cannulation Problem with peripheral VA ECMO: Lower body receives better perfusion Possible poor perfusion of coronary and cerebral vessels Oxygenated blood returned to aorta so lungs get little O2 rich blood -> may exacerbate lung ischemia

Peripheral V-A ECMO Problems Left ventricular distention ECMO does not directly decompress the left ventricle Typically ~ 80% of blood thru ECMO circuit ~ 20% of blood thru left ventricle Without adequate ejection, blood will accumulate in under pressure Can lead to severe pulmonary edema and fatal pulmonary hemorrhage Prevention: inotropes to maintain LV ejection, minimize afterload (manage BP), IABP Treatment: atrial septostomy or LV vent to allow left atrial blood to flow into the ECMO circuit Perfusion to foot with femoral artery cannulation Femoral perfusion cannula to reduce limb ischemia risk

Peripheral V-A ECMO Problems Aortic root thrombus Peripheral ECMO blood travels retrograde up the descending aorta until it meets blood ejected by the left ventricle Some degree of stagnation may occur → thrombus (stroke risk) Avoid by ensuring native left ventricular ejection Cerebral hypoxia Fully saturated blood from ECMO circuit meets blood ejected from native left ventricle Location of the “mixing point” depends on amount of ECMO support and degree of LV ejection Severe myocardial dysfunction → mixing point in the proximal aorta As heart function improves →mixing point migrates more distally Hypoxic blood may perfuse proximal aorta, coronary and cerebral arteries Femoral ABG shows fully saturated blood; Rt radial ABG shows hypoxia Treatment: Adjust ventilator with ↑FiO2, PEEP Run You Tube video clips: VenoArterial ECMO Mayo Clinic (7:35)

ECMO Goals Maintain adequate gas exchange with lowest FiO2 and airway pressures Typical ventilator settings: FiO2 titrated to keep PaO2 80-100 mm Hg; SpO2 ~ 95% Respiratory rate ~ 8 breaths / min Tidal volume 5-8 ml / Kg PEEP 5 cm H2O Airway pressures below ~ 35 cm H2O During weaning, ventilator re-set to support native blood flow and oxygenation through lungs

Delineation of Roles Surgeon – surgical management; cannulates the patient; manipulates, adjusts and changes ECMO components; prescribes interventions Perfusionist – primes circuits and supports patient during initial set-up; available on call after patient is stable; checks circuit daily; consults with team Nursing – manages the patient and monitors ECMO; identification of patient and circuit problems ICU Team – medical management of patient; prescribes interventions

ECMO Management ↓ in arterial saturation and ↓ PaO2 = need to ↑ECMO blood flow Make small changes at each interval Example: 4 LPM to 4.5 LPM Monitor ABGs, SpO2, ET CO2 Add volume to increase cardiac output Typically do not make changes to the mechanical ventilator until patient is ready to attempt weaning from ECMO

ECMO Problems Bleeding Clotting Infection Re-exploration to find source and decide treatment Factors: Prolonged CPB time, anticoagulation, thrombocytopenia, hemolysis due to the device Clotting Anticoagulation to decrease the risk of clot formation Infection Multiple invasive lines, cannulas, immobility Scrupulous attention to infection control practices Cannula dislodgement = EMERGENCY Turn off pump, clamp cannulas close to pt Prepare to open chest or return to OR

ECMO Problems Hypothermia Neurologic assessment Skin care Risk because patient’s blood outside body Interferes with normal cellular function Neurologic assessment High risk of cerebral emboli Recommend daily awakening to assess neuro function Skin care Patients susceptible to complications of bed rest Emotional support / education needs Family also your patient; enlist chaplain & social worker

Weaning of ECMO Generally try for at least 48 -72 hrs of stability, or longer depending on the reason for ECMO Assess readiness to wean: Decrease flows; observe hemodynamic waves; TEE imaging MDs manipulate pumps; perfusionist might assist Evaluate arterial line for LV function; PAWP for LA function Evaluate PAP for RV function; CVP for RA function Increases in CVP, PAP, PAWP or ↓BP indicate pt not ready to wean

Mobilizing the ECMO Patient Types of cannulas determine level of activity Central or subclavian cannulas – ROM and OOB Peripheral cannulas – ROM and in-bed activities Careful protocol enlisting support of nursing, perfusionist, physical therapy with MD order Patient & family education essential Only perfusionists do critical hook ups Secure the cannulas Adequate gas supply Console battery charged; two working cell phones if leaving ICU

Mobilizing the ECMO Patient

“Carla” Woman; early 30’s; early Sept fever of undetermined cause; worsening oxygenation; admit to local hospital Early Oct transferred to BJH for ECMO Lungs did not improve; listed for lung transplant Gradually stronger with rehab; remained on V-A ECMO Dec 24 – lung transplant

Outcomes

Summary ECMO when needed in select patients for respiratory or cardiorespiratory support Patient management Monitor progress toward goals Assess for complications Include family in care, planning and transplant evaluation Evolving technologies Increased pt activity Improve physiology for transplant success

Summary Critical care nurses play a central role Providing direct patient care Coordinating care among the team members Optimal patient outcomes depend upon carefully monitoring effectiveness and complication of ECMO