PERFUSION TECHNIQUE Flashcards
The term “perfusion” is derived from the
French verb ‘perfuse’ meaning?
to ‘pour over or through’
They employ artificial blood pumps to propel open-heart surgery patients’ blood through their body tissue, replacing the function of the heart while the cardiac surgeon operates.
Perfusionists
a skilled, allied health professional, trained and educated specifically as a memberof an open- heart, surgical team responsible for the selection, setup, and operation of a mechanical device commonly referred to as the heart- lungmachine
Perfusionists
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)
What is the main objective of ECMO and ECLS?
provide systemic perfusion and gas
exchange allowing the heart and/or lungs to rest and recover to different
modality of support or to transplantation
development of a roller pump in the 1930’s led to the first successful extracorporeal assist in 1953
Dr. John Gibbon
revolutionized the artificial lung with
the development of synthesis of silicone rubber
Kammermeyer
developed an approach to continuously titrate coagulation with Heparin
Bartlett and Drinker
reported the first successful cardiac ECMO run of 36 hours in a 2 year old infant with cardiac failure
Bartlett, Gazzaniga et al.
provides a bloodless field for cardiac surgery
Cardiopulmonary bypass (CPB)
What is the mechanism of CPB?
It incorporates an extracorporeal circuit to
provide physiological support in which venous blood is drainedto a reservoir, oxygenated and sent back to the body using a pump.
True or False: Team effort between surgeon, perfusionist and anaesthesiologist is paramount for the successful use of CPB
True
True or False: ECMO circuit includes pumps, cannulae, tubing, reservoir, oxygenator, heat exchanger and arterial line filter
False - CPB
What are the 2 types of pumps?
- Roller pump
- Centrifugal pump
Roller pump includes ____
positioned on a rotating arm, which
compress a length of tubing to produce
forward flow
2 rollers
In roller pump, the compression of tubing produces forward flow, what can this action produce?
haemolysis and tubing debris
True or false: Use of roller pumps for longer procedure is discouraged
True
Centrifugal pump consists of _____ cones within housing
Impellers/stacked
What happens to a centrifugal pump when rotated rapidly?
Negative pressure is created at one inlet, positive on the other = propelling blood forward
True or false: Centrifugal pumps can’t improve platelet preservation, renal function and neurological outcomes in longer cases.
False: It can
Which pump is afterload independent, no flowmeter required, and increase blood trauma and tubing debris?
Roller pump
Which pump is retrograde flow possible, expensive but for long-term use, portable, and has no disruption?
Centrifugal pump
Which pump has no backflow occurs, cheap, short-term use, bulky, and has circuit disruption?
Roller pump
Which pump is afterload depndent,needs flowmeter, has descreased blood trauma and tubing debris?
Centrifugal pump
Which pump has lesser risk of air embolism and more priming volume?
Centrifugal pump
Which pump has greater risk of air embolism and less priming volume?
Roller pump
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
Cannulae
are used during most open-heart surgeries, where two cannulae are inserted into the superior and inferior vena cava and joined by a Y-piece
Venous cannulae/single-stage cannulae
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.
Dual-stage cannulae
are largely of historical interest in the era of
membrane oxygenators.
Bubble oxygenators
consist of hollow microporous polypropylene fibres (100–200 μm internal diameter)
Oxygenator
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
Tubing
Newer plasticisers such as _______ have less leaching and are under investigation.
dioctyl adipate
True or false: Closed reservoirs have a limited volume capacity, but offer a smaller area of blood contact with artificial surfaces
True
They collect the blood drained from the ____. Open reservoirs are more commonly used. They allow passive removal of entrained venous air along with the option of applying vacuum to assist drainage.
heart
a method of
myocardial protection where the heart is perfused with a solution
to cause electromechanical arrest which reduces myocardial
oxygen consumption.
Cardioplegia system
True or false: Cardioplegia can be crystalloid (cold) or blood-based (warm or
cold); can be given continuously or intermittently.
True
solutions are commonly used for cardioplegia system?
Potassium based solution
Blood cardioplegia is a
combination of oxygenated blood and crystalloid in a ratio ranging
from
1:! to 8:1
True or False: The deairing of CPB circuit is done by priming solutions, consisting of a mixture of crystalloids and colloids. P
True
True or false: riming causes haemodilution which improves flows during hypothermia.
True
Heparin ____ units/ml is added to the prime.
3–4 units/ml
During anterial cannulation, systolic pressure should be __ to __ mm Hg
to reduce the risk of aortic dissection.
90-100
The aortic cannulation is done first to provide volume resuscitation in case of hypotension associated witvenous cannulation.
Initiation
is a point-of-care test used to assess the
adequacy of heparinisation. Normal ACT ranges from
80 to 120 s
ACT must be monitored every?
30-40 mins
Perfusion pressure is used as a surrogate marker of organ perfusion and
should be maintained between
50 and 70 mmHg
it evoked potentials and
transcranial Doppler can be used to assess the adequacy of cerebral blood
Cerebral oximetry
True or false: blood level in the reservoir should be monitored to prevent air embolism. Central venous pressure (CVP) should be low. High CVP indicates a good
venous return.
Both are true
Glucose is maintained between mg/dL.
Anaesthesia can be maintained by inhalational route or total intravenous
anaesthesia can be given.
120 and 180 mg/dl
is frequently used during CPB for its presumed organ protective effects
Hypothermia
is a point-of-care test used to assess the
adequacy of heparinisation. Normal ACT ranges from 80 to 120 s
Activated clotting time (ACT)
true or false: Blood viscosity decreases with hypothermia and allows maintenance of a higher perfusion pressure despite haemodilution.
However, hypothermia reversibly inhibits the clotting factors and platelets.
1st false - increases dpt
2nd true
CPB can be used for the induction of total body hypothermia, a state in
which the body can be maintained for up to __ minutes without perfusion
(blood flow). If blood flow is stopped at normal body temperature,
permanent brain damage normally occurs in __ to __ minutes — death
may follow shortly afterward.
45 mins; 3-4 mins
used after completion of the surgical repair before protamine administration, with blood removed from the arterial line and returned to the venous line after passing through the haemofilter.
Modified ultrafiltration (MUF)
removes inflammatory
mediators and excess fluid thereby producing haemoconcentration.
Ultrafiltration
the process where extracorporeal support is gradually withdrawn as the heart takes over the circulation
Weaning
Nasopharyngeal temperature should not exceed __, although authors accept temperature range of 35.5°C–36.5°C.
37°C
can be associated with bleeding, cannula malposition
causing selective cerebral perfusion, plaque dislodgement and dissection.
Arterial cannulation - mechanical cannulation
can be associated with bleeding, cannula
malposition/air lock causing an inadequate return, leading to cerebral and
splanchnic congestion
Venous cannulation - mechanical cannulation
What are the systemic complications of CPB?
- Acute respiratory distress syndrome
- Qualitative and quantitative platelet dysfunction
- Inflammatory response and hypotension can cause acute kidney injury (AKI)
- Risk factors are prolonged bypass time, sepsis and diabetes.
- The spectrum of cerebral injury ranges from cognitive dysfunction to
stroke.
T or F: Subclinical myocardial injury can occur due to cross clamping of the
aorta in spite of cardioplegia.
True
