ECMO / Bypass / Dialysis

Hyper, metabolic acidosis, blood volume, uremia, albumin

Patient with hx ESRD vitals and key findings

• __kalemia

• __ __ (acid base state)

• __ __ overload

• __ (blood finding)

• Low __ in blood

SOB, sharp central, confusion, leg

ESRD Sx

• __ (resp)

• __, __ chest pain

• __ - AMS

• __ swelling

Peripheral, friction rub, T waves, breath sounds, metabolic acidosis

ESRD sx PE

• __ edema

• Cardiac “__ __”

• EKG - peaked/tented _ __

• Diminished __ __ bil

• Increased work of breathing from __ __ (acid-base)

Extracorporeal Membrane Oxygenation (ECMO)

Artificial gas exchange and circulation

Venous blood, external, gas exchange

ECMO Goals

• Withdraw __ __ and pump through an __ (internal/external) oxygenator

  • Adds O2 and removes CO2 - Facilitating __ __

Vein, vein, right atrium, gas exchange

V-V ECMO

• Drain blood from __ → oxygenate → Return blood via __ to the __ __ (heart)

• Support __ __ of failing lungs

Vein, artery, right to left shunt

V-A ECMO

• Drain blood from __ → oxygenate → Return blood via __

• Creating a __ __ __ __ = stable O2 supply to heart

Heart failure, PE, cardiac arrest

Why might a patient require a V-A ECMO rather than a V-V ECMO?

• For (3)

Right atrium, vena cava, vein, anesthetic, aorta, artery

ECMO

• Venous blood is typically withdrawn from the__ __, __ __, femoral __ (2-heart, 1-vasc)

• With some machines, volatile __ gases can be added to oxygenator

• In V-A ECMO, blood is often returned via a cannula into __ or femoral __ (1-heart, 1-vasc)

Healthy Heart (Normal circulation)

Poor Gas Exchange, requiring V-V ECMO

Poor Circulation, requiring V-A ECMO

Severe respiratory failure from ARDS

V-V ECMO is most appropriate in which scenario?

V-V ECMO

Support when lungs are NOT oxygenating adequately, but systemic and pulmonary blood flow are preserved → Respiratory failure

V-A ECMO

Support when heart is not pumping adequately (+ or lung dysfunction) → shunt

Cardiopulmonary Bypass

Artificial ventilation and circulation device during open-heart surgery

Movement, bleeding, oxygen delivery, heart tissue

Heart surgery requirements for CP Bypass

• Minimize heart __

• Minimize __

• Maintain __ __ to systemic tissues

• Preserve __ __

Venous Cannula

Sends deoxygenated blood to external oxygenator (CP B cannula)

Aortic Cannula

Returns oxygenated blood (CP B cannula)

Cardioplegia, left ventricle

Additional cannulae in CP B for:

• Administering __ solutions (antegrade, retrograde, or both)

• Draining blood from the __ __ (heart)

Bronchial circulation, thebesian veins, aortic valve regurgitation

Blood accumulates in the left ventricle over time

• leads to (3)

O2 demand, stress, oxygenator, air, embolism

Left ventricular vent

• LV distension increases myocardial __ __

• Must drain to avoid __ to the heart

  • Filter drained blood and send to the __ (component)

• Also removes __ introduced during surgery → To prevent an __ (condition)

20-35, 10-15

Myocardial tissue preservation in CP B

• Systemic and local hypothermia

  • Core temperature actively or passively lowered to __-__ degrees C

  • Cardiac temperature reduced to __-__ degrees C

Crystalloid fluid, potassium, bicarbonate, glucose, cold

Cardioplegia solution for CP B

• Blood or __ __

• __ and __ (electrolytes)

• __ (macromolecule)

• __ (temp)

Cold cardioplegia, topical cooling, Ca2+, contraction

Myocardial tissue preservation in CP B

• Myocardial temperature can be reduced via __ __ solution and __ __ with an ice slush

• Cardioplegia solutions must have carefully controlled __ (ion) levels, excessive leads to __ of heart

Cardioplegia pump, coronary, aortic clamp

Cardioplegia administration in CP B

• A separate __ __ allows for better control

• Admin into __ vasculature (coronary arteries excluded by an __ __)

Aortic clamp, aorta, coronary sinus

Cardioplegia admin into coronary vasculature in CP B

• Coronary arteries excluded by an __ __

• Antegrade via catheter in __ (goes L to R)

• Retrograde via catheter in __ __ (goes R to L)

Dialysis

Artificial renal function in case of renal failure

Hyperfiltration, progressive, GFR

• __ = High whole kidney GFR, high single nephron GFR

  • __ destruction of more nephrons

  • Failure of compensatory mechanisms will lower __ over time

CKD Stage III

Low whole kidney GFR, high single nephron GFR

ESRD

Very low whole kidney GFR, very high single nephron GFR

60, 3

Chronic Kidney Disease (CKD) Criteria

GFR < __ mL/min for _ months or longer

I, 90

Stage _ CKD: Kidney damage with normal or elevated GFR

• GFR is __ or higher

II, 60-89

Stage _ CKD: Kidney damage with mild decrease in GFR

• GFR is __-__

III, 30-59

Stage _ CKD: Moderate decrease in GFR

• GFR is __-__

IV, 15-29

Stage _ CKD: Severe decrease in GFR

• GFR is __-__

V, 15

Stage _ CKD: Kidney failure or ESRD

• GFR is less than __

30, 15

CKD

• Stages I-III are in GFR increments of __ ml/min/1.73

• Stage IV-V are in GFR increments of __ ml/min/1.73

Metabolic wastes, body water, buffers

Functions of Dialysis - (3)

• Remove __ __

• Remove excess __ __

• Replenish __

Acid/base, electrolyte, hyperkalemia, intoxication, overload, uremia

Emergent Indications for Dialysis = AEIOU

• __/__ disturbances

• __ disturbances (i.e. __**)

• __ (i.e. salicylates)

• __ (of volume)

• __ - GU

Semi-permeable, concentration gradient, solute, permeability, surface area, flow rate

Dialysis is diffusion across a __ __ membrane

• Affected by…

  • __ __ between blood and dialysate

  • __ size

  • Membrane __

  • __ __ (dimension)

  • __ __ of blood to dialysate

Equilibrium, plateaus, concentration gradient

In Dialysis

• Since smaller solutes diffuse faster, they reach __ and clearance __

• Larger solutes diffuse slower, maintaining their __ __ between blood and dialysate

Ultrafiltration

Setting pressures to remove appropriate volume of fluid over time

Hydrostatic, blood compartment, dialysate component

Ultrafiltration in Dialysis

• Dialysis machine generates a __ pressure gradient

  • Positive pressure applied to the __ __

  • Negative pressure (suction) applied to the __ __

High, fistula, graft, central line

Vascular access for hemodialysis

• Need stable access to bloodstream with __ blood flow

• Options - Arteriovenous __, arteriovenous __, and __ __

AV Fistula

Vein connected to artery, with increased pressure and flow in vein downstream to anastomosis (for dialysis)

Months, weeks

• AV Fistula is created surgically several __ prior to dialysis

• AV Graft is created surgically several __ prior to dialysis

Pressure, bleeding

Why should you avoid venipuncture and blood pressure measurements on a limb with a fistula?

• Higher __ to fistula than typical vein will lead to higher risk of __ or infection

AV Graft

Connects artery to vein, with synthetic tube; used sooner (for dialysis)

Central Line

Large double or triple lumen catheters for immediate use (in dialysis)

Subclavian, IJV, lower flow

Central Line

• Think tube to the __ or __, used immediately

• Con - __ __ than AV fistula or graft

Flow, resistance

Why are large-gauge catheters used for central hemodialysis lines?

• Maximize highest __ via Ohm’s Law and decrease __

Peritoneal Dialysis

Dialysis solution localized, equilibrates with ECF and drains

Home, longer

Peritoneal Dialysis

• Patients can perform at __, but takes __ than hemodialysis

Anaerobic, lactic acid, bicarbonate

Why does myocardium produce acidic metabolites during bypass?

• Myocardium reacts on __ metabolism in bypass, producing __ __

• __ in cardioplegia solutions neutralize this