SPDX PERFUSION

• Weaning


  : Involves gradual withdrawal of extracorporeal support as the heart takes over the circulation, requires a period of rewarming and deairing of the heart
• Ultrafiltration


  : Removes inflammatory mediators and excess fluid thereby producing haemoconcentration, conventional ultrafiltration uses a haemofilter, modified ultrafiltration is used after completion of the surgical repair
• Priming


  : The deairing of CPB circuit is done by priming solutions, consisting of a mixture of crystalloids and colloids
• Initiation


  : During arterial cannulation, systemic pressure should be 90-100 mm Hg, after venous cannulation, venous clamp is gradually released to establish full CPB and then ventilation is discontinued
• Anesthesia and Monitoring on CPB


  : Perfusion pressure is maintained between 50 and 70 mmHg, blood level in the reservoir should be monitored to prevent air embolism, glucose is maintained between 120 and 180 mg/dL
• Temperature Management


  : Hypothermia is frequently used during CPB for its presumed organ protective effects, but can reversibly inhibit the clotting factors and platelets
• Generating blood pressure.


  Contractions of the heart generate blood

  pressure, which is responsible for moving

  blood through the blood vessels.
• Routing blood.


  The heart separates the pulmonary and

  systemic circulations and ensures better

  oxygenation of the blood flowing to the

  tissues
• Ensuring one-way blood flow.


  The valves of the heart ensure a one-way

  flow of blood through the heart and blood

  vessels.
• Regulating blood supply.


  rate and force of heart contractions

  change to meet the metabolic needs of the

  tissues, which vary depending on such

  conditions as rest, exercise, and changes in

  body position.
• perfusionist


  it is a skilled, allied health

  professional, trained and educated specifically as

  a member of an open-heart, surgical team

  responsible for the selection, setup, and

  operation of a mechanical device commonly

  referred to as the heart-lung machine.
• Perfusionists


  ____ are capable of combining sterile

  tubing and artificial organs to build an ECC to

  meet the needs of several physician specialists to

  treat patients with specific operable diseases.
• Extracorporeal Membrane

  Oxygenation (ECMO) and

  Extracorporeal Life Support

  (ECLS),


  a broader term used

  synonymously, both include

  various modalities of

  temporary mechanical

  cardiopulmonary assistance

  used to support patients with

  severe heart and/or lung

  failure which is unresponsive

  to optimal conventional care.
• Extracorporeal Membrane

  Oxygenation (ECMO) and

  Extracorporeal Life Support

  (ECLS),


  This technology

  involves redirecting the blood flow

  from the patient's body through

  cannulas and connecting tubing to

  a gas exchange membrane and

  then returning the blood by

  means of a pump back to the

  patient's circulation

  .
• Dr. John Gibbon


  development of a

  roller pump in the

  1930's led to the

  first successful

  extracorporeal assist

  in 1953
• Kammermeyer

  ​

  revolutionized the

  artificial lung with

  the development

  of synthesis of

  silicone rubber
• Bartlett and

  Drinker


  developed an

  approach to

  continuously

  titrate coagulation

  with Heparin
• Bartlett,

  Gazzaniga et al.


  reported the first

  successful cardiac

  ECMO run of 36 hours

  in a 2 year old infant

  with cardiac failure
• Cardiopulmonary bypass (CPB)


  provides a

  bloodless field for cardiac surgery.
• Cardiopulmonary bypass (CPB)


  It incorporates an extracorporeal circuit to

  provide physiological support in which venous

  blood is drained to a reservoir, oxygenated and

  sent back to the body using a pump.
• Modern CPB machines


  have systems for monitoring

  pressures, temperature, oxygen

  saturation, haemoglobin, blood gases,

  electrolytes as well as safety features such

  as bubble detectors, oxygen sensor and

  reservoir low-level detection alarm.
• Suckers


  (to remove blood from surgical field),

  ​
• vents


  (to decompress the heart),
• haemofilters


  (for ultrafiltration)
• Roller pump


  includes two rollers

  positioned on a rotating arm, which

  compress a length of tubing to produce

  forward flow
• Centrifugal pump


  consists of

  impellers/stacked cones within housing
• Centrifugal pump


  When rotated rapidly, negative pressure

  is created at one inlet, and positive

  pressure at the other, thus propelling

  the blood forward.
• Centrifugal pump


  may improve platelet

  preservation, renal function and

  neurological outcomes in longer cases
• Roller pump


  This action can produce haemolysis and

  tubing debris, the incidence of which

  increases with time
• CANNULAE


  connect the patient to the circuit and hence to the CPB

  machine. They are made of polyvinylchloride (PVC) and are wire

  reinforced to prevent obstruction due to kinking.
• Venous cannulae: single-stage cannulae

  are used during most openheart

  surgeries, where two cannulae are inserted into the superior and

  inferior vena cava and joined by a Y-piece
• Dual-stage cannulae


  are used for most closed-heart procedures,

  where a single cannula is inserted into the right atrium. Drainage

  occurs through gravity. Vacuum applied to the reservoir allows the

  use of smaller cannulae and tubing, thus decreasing the circuit

  volume.
• Bubble oxygenators


  are largely of historical interest in the era of

  membrane oxygenators.
• Membrane oxygenators


  consist of hollow microporous polypropylene

  fibres (100-200 μm internal diameter). Blood flows outside the fibre

  while gases pass inside the fibre, thus separating the blood and gas

  phases. They have lesser propensity for air embolism and give greater

  accuracy in blood gas control. Newer designs have an integrated filter

  to manage emboli, thus making additional arterial filters unnecessary.
• heat exchanger


  A ______ is integrated with the oxygenator and placed

  proximal to it to reduce the release of gaseous emboli due to

  alterations in the temperature of saturated blood.
• TUBING


  These are generally made of PVC, due to PVC's

  durability and acceptable haemolysis rate.
• Plasticisers


  like di(2-ethylhexyl) phthalate which are added to

  impart flexibility are potentially toxic and shown to

  leach from the tubing. Newer plasticisers such as

  dioctyl adipate have less leaching and are under

  investigation.
• RESERVOIR


  They collect the blood drained from the heart
• Open reservoirs


  are

  more commonly used. They allow passive removal of entrained venous air along with the option of applying vacuum to assist

  drainage.
• Closed reservoirs


  have a limited volume capacity, but offer a

  smaller area of blood contact with artificial surfaces. This produces

  less inflammatory activation, better sterility and reduces postoperative

  transfusion. They, however, require a separate circuit for

  processing suctioned blood.