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PERFUSION

Stockert  (Sorin Group)

The Society of Clinical Perfusion Scientists of Great Britain and Ireland 

Perfusion Protocol

Equipment Selection:

• All perfusionists should be familiar with the function and operation and when necessary the calibration of all appropriate equipment necessary for the safe practice of perfusion.
• The appropriate equipment (i.e. oxygenator, tubing pack and blood cardioplegia delivery system) should be selected in order to facilitate the requirements of the perfusionist, surgeon and anaesthetist, for the particular procedure to be undertaken.
• A roller pump will be used in all cases unless otherwise directed by the consultant surgeon, where the Biomedicus pump will be the device employed.


Assembly of the Cardio-Pulmonary Bypass Circuit:

This should be undertaken using aseptic techniques, in conjunction with the manufacturers instructions and relevant warnings as specified in their handbooks. All assembly should be done with reference to manufactures instructions

• Check overall cleanliness of the pump.
• Check integrity of electrical connections and interconnections.
• Check battery backup.
• Check gas supply and delivery systems from outlet to points of delivery.
• Check anaesthetic gas scavenging system.
• Check UPS (uninterruptible power supply)
• Check availability of appropriate tubing, oxygenator, haemofilter, intra-aortic balloon pump, and cardioplegia delivery system.
• Check integrity of sterile wrapped plastic bag containing the oxygenator, AV sash, pump tubing, cardioplegia tubing etc
• Check all connection ports are capped.



Cardiopulmonary Circuit Assembly:

• Hands should be washed prior to assembly of the cardiopulmonary bypass circuit.
• Place the oxygenator unit into the holder, ensuring that it is seated correctly and secured.
• Assemble the cardiopulmonary bypass circuit, ensuring aseptic techniques are observed.
• Ensure that all connections are secure and that all connections, which are subjected to high pressures, are tied with nylon ties for added security.
• The cardiopulmonary bypass circuit should then be flushed with CO2 for a minimum of 3 minutes, prior to priming the circuit.
• The water lines from the heater-cooler unit should be connected to the heat exchanger compartment of the oxygenator and to the heat exchanger compartment of the blood cardioplegia delivery system. Both units should then be checked for leaks, and air should be cleared from the heat-exchange device.
• Set the water temperature to 380C.
• The direction of all pumps should be checked for clockwise rotation.
• All pump-flow direction guards should be correctly in place.


Circuit Priming
• The cardio-pulmonary bypass circuit should be primed with the constituents listed below, or as requested by the Consultant Cardiac Surgeon, or Consultant Anaesthetist prior to the procedure.

Hartmann’s solution. 2000ml.
Hartmann’s 1000mls and Gelofusine 1000ml
Heparin. 10,000 i.u.
Cyclokapron. (As requested) 1.0g.
Aprotinin (Trasylol) (as requested) 2,000,000 i.u. .


Priming volumes ~ weight, and Hb. Additional constituents.

• Introduce priming solution into the venous reservoir. Gravity prime the cardiopulmonary bypass circuit.
• Insert the arterial pump boot into the head, ensuring that it is sitting correctly.
• Circulate the prime through the cardiopulmonary bypass circuit, ensuring the removal of all visible air (avoid the use of clamps wherever possible – never use clamps on polycarbonate devices or connectors).
• Run the arterial pump (designated pump 5, furthest pump on the right) at a flow of approximately 4.5 l/min. and pressurise the system by partial occlusion of the venous line to achieve a pressure of 150-200 mmHg. Visually inspect the complete cardiopulmonary bypass circuit for leaks and/or visible air.
• Stop the pump, clamp all lines and turn off all shunts. Check the arterial pump occlusion using a falling column of fluid technique (1cm/min drop).
• Remove clamps, restart pump, and circulate through sash.
• Connect the arterial, venous and cardioplegia temperature probes.
• Connect and enable the level sensor and arterial microbubble sensor.
• Connect and calibrate the arterial and cardioplegia pressure transducers.
• Set alarms.

Alarms

• Reservoir level sensor set at 300mls.
• Arterial pressure alarm set to 300mmHg.
• Cardioplegia transducers alarms: - Antegrade set to 250mmHg, Retrograde set to 150mmHg.



Patient Demographics

• Height.
• Weight.
• Body surface area calculated or obtained from nomogram.
• Calculate the flow rate 2.4 l/min/m2 (BSA) at a body temperature of 37oC.
• Biochemistry
• Haematology.
• Relevant medical history eg previous heart surgery, diabetes, renal failure or CVA.
• Prior to the start of bypass the patient data should be entered onto the Cardiopulmonary Bypass Record. The date, operation, surgeon, anaesthetist perfusionist and type of oxygenator (with serial number) being used should all be recorded.
• The heparin dose (300i.u/Kg), prime volume and constituents recorded on chart

Pharmacology

• The perfusionist shall only prepare drugs as specified by the consultant surgeon or consultant anaesthetist, adhering to the current trust policy.
• The administration of drugs shall be performed under the direction and supervision of the consultant surgeon or consultant anaesthetist.
• All medications must be prepared using an aseptic technique.
• All drugs drawn up must be labelled with the
 Drug name
 Drug concentration.



Drugs and fluids are administered as routine:

• Hartmanns
• Mannitol
• Heparin
• Blood Cardioplegia: (high dose: i.e 40mls of St Thomas 1 Cardioplegia solution into a 500ml bag of Ringers while low dose is 20mls of St Thomas 1 Cardioplegia solution.) Both strengths of Cardioplegia should be administered at a ratio of 4 parts of blood to 1 part of cardioplegia.
• Gelofusine
• 6% ELO-HAES




Drugs and fluids administered with direct consultation with the surgeon and anaesthetist:

• Sodium Bicarbonate
• Potassium
• Trasylol
• Cyclokapron
• Magnesium Sulphate
• Frusemide
• Phentolamine
• Phenylephrine
• Aramine
• Calcium Chloride
• Blood Products



Blood Flows
• Blood flow during cardiopulmonary bypass should be maintained at: -
2.41/min/m2 (BSA) at a body temperature of 37oC. Proportionally being reduced to 1.61/min/m2 (BSA) at a body temperature of 28oC
• It is however acceptable in the case of adults to exceed the calculated blood flows at 2.41/min/m2 (BSA) by up to 1.01/min. in instances of hypotension and or reduced venous saturation.
• When using a Venous Saturation Monitor, sats >65% should be aimed for.



Anti-Coagulation

• Heparin is the anti-coagulant of choice.
• The loading dose, which is administered by the anaesthetist, will be 300i.u/Kg of the patient’s body weight.
• Samples should be taken after a period of 3-5 minutes post administration. This should result in an A.C.T. (Activated Clotting Time) which is >480 seconds, or 3 times the base result for the A.C.T where Kaolin Tubes (yellow top-tubes) are used.
• In cases where Aprotinin (Trasylol) is used and CeLite ACT tubes are used, the clotting time should be >750 seconds.
• Cardio-pulmonary bypass should not be initiated until the A.C.T. results have reached these levels.
• In emergency LIFE THREATENING situations however, cardio-pulmonary bypass may be initiated with A.C.T.s below these levels, but only on the DIRECT INSTRUCTION OF THE SURGEON IN CHARGE.
• Where the A.C.T. result is below the recommended level, post heparinization, the Perfusionist must inform both the anaesthetist and surgeon, in order that more heparin or on occasions FFP (Fresh Frozen Plasma) administered and the ACT rechecked.
• During the cardio-pulmonary bypass procedure it is the responsibility of the Perfusionist to maintain adequate levels of anti-coagulation, monitoring the A.C.T. every 20 - 30 minutes, administering further doses of Heparin as and when required.

Cardioplegia

• All surgeons use the 4:1 blood cardiolegia delivery system to achieve and maintain asystole (for Surgical preferences see Appendix 3) This consists of 4 parts blood and 1 part crystalloid (Ringers) cardioplegia. Initial cardiolpegic doses consist of 4 parts blood to 1 part HIGH K+. Maintenance doses consist of 4 parts blood with 1 part LOW K+.
• High K+ concentration is obtained by injection of 40mls St Thomas 1 Cardioplegia solution into a 500ml bag of Ringers.
• Low K+ concentration is obtained by injection 20ml St Thomas 1 Cardioplegia solution into a 500ml bag of Ringers.
• Where a long bypass procedure is envisaged a 1litre Low K+ can be prepared using 40ml St Thomas Cardioplegia in a litre bag of Ringers.
• Antegrade via ostial cannula if valve regurgitant or via 12FG Root Cannula if competent valve.
• Blood cardioplegia should be started at 250ml/min.
• Retrograde blood cardioplegia should be started at 180-220ml/min. The coronary sinus pressure should be monitored during infusion and should be maintained between 20-4-mmHg. The surgeon should be informed of the retrograde cardioplegia flow and the coronary sinus pressure as:
High flow and low pressure:
- the catheter might have been displaced out of the coronary sinus
- the sinus ostium might be very long and require additional digital pressure to occlude in addition to reinflating balloon.
Low flow and high pressure:
- the catheter may need to be withdrawn if too far in or the tip might be obstructed in a side branch of the coronary sinus.


Intermittent Cross-Clamp Ventricular Fibrillation


Where a Surgeon uses Intermittent Cross-Clamp Fibrillation the heart is fibrillated and the aorta cross-clamped. The ischaemic time should be noted and surgeon should be informed every 10 minutes of the time. Between periods of ischaemia, the heart is reperfused. After the distal anastamosis is completed the aortic cross-clamp is released and the heart defibrillated. A side-biting clamp is applied and the proximal anastamosis is then preformed. The heart is fibrillated again and the process is repeated until all anastamosis are performed. During the final anastamosis (usually LIMA to LAD) the patient is rewarmed.



Cardiopulmonary Bypass

Pre – Bypass Check List: (See Appendix1)

• Drugs
• Cardioplegia solution
• Cannulae: as per the requirements of each individual Consultant Cardiac Surgeon
• ACT machine with Kaolin (yellow top) ACT tubes
• Heater/cooler.


In Theatre

• Prior to the initiation of the cardio-pulmonary bypass, the heart-lung machine must be positioned near to the surgical field.
• The medical air/O2 lines are connected to the mains pendant, the condition and status of the utility systems and the connections being noted.
• The tray containing the sterile arterio-venous loop, the suction tubing and where applicable topical cooling device must be handed to the scrub nurse, who in turn will ensure that arterio-venous sash is secured to the holder secured to the operative site.
• Attach the pump suckers from the table to the appropriate pump inlets and check for direction of flow.
• The Perfusionist should check that all visible air has been removed from the perfusion circuit, the intra-cardiac and vent suction lines have been correctly connected
• A visible check for the direction of flow in these lines is made by the perfusionist immersing the tubing into a container of saline.
• Once the check has been performed the suction is turned off until the patient has been fully heparinized and the ACT checked.
• The blood cardioplegia line should be connected and primed.
• The A-V loop should be clamped off, and the main arterial pump left to re-circulate at 500 – 1000 ml/min. via the re-circulation line.
• The Vaporiser, (where required, see Appendix 4) should be connected with level checked, the blood level and air embolism detectors should be connected and the alarms must be enabled.
• The perfusionist must be present in theatre once the operation is commenced (sternum opened), and remain in theatre until the sternum is closed. Sudden decompensation of the patients heamodynamics can occur and require immediate commencement/recommencement of Cardiopulmonary Bypass.


Initiation of Cardiopulmonary Bypass:

• After the administration of heparin, the surgeon will request to “divide the sash”. The perfusionist must acknowledge this.
• The pump is stopped, the arterial and venous line are clamped
• Any bleed and sample lines should be closed and recirculation lines clamped.
• Inform surgeons lines are clamped
• The surgeon will clamp and divide the arterial and venous lines.
• After determining the correct tubing length against the patient chest the surgeon will cut the lines to the appropriate length.
• Ensure arterial and venous lines remain clamped at all times until bypass is initiated
• After cannulation of the aorta, the surgeon will remove the clamp on the arterial line and may request the perfusionist to fill the arterial tubing to displace air from the tubing during connection to the aortic cannula. Remove the clamp on the pump end of the arterial line and slowly turn on pump to expel any air while connection is made.
• After connecting the cannula the surgeon will remove his or her clamps and inform perfusionist that the line is fully open.
• Once the arterial line has been connected the perfusionist must ensure that the arterial pump is stopped and that all shunts are closed.
• The clamp is then removed from the arterial line and the pulsation noted. The surgeon is informed “good swing”
• The pressure reading on P1 (the perfusion circuit transducer) which is measured at the top of the arterial filter port, should equate to the patient’s mean arterial blood pressure indicating correct positioning of arterial cannula. In some centres pre and post oxygenator membrane pressures are recorded.
• If there is poor pulsation or no pulsation, ensure all clamps are removed from the arterial line and that there is no other obstruction to flow. If still no or poor pulsation inform surgeon.
• When the ACT reaches a level, which is greater than 300 secs. The suction is turned on and the surgeon informed of this fact.
• Once artery cannulated, venous cannula (single 2-stage RA/IVC) or bi-caval cannula are inserted.
• Bypass may be initiated when levels of anti-coagulation have reached satisfactory levels as previously stated, bypass circuit properly connected and perfusionist completed all his checks.
• Cardio-pulmonary bypass can be initiated on the instruction of the surgeon in charge. Remove arterial clamp and start arterial pump. Watch arterial line pressures on P1. If excessive pressure (>260mmHg) inform surgeon of high line pressures, stop pump and clamp arterial line.
• If line pressures are satisfactory slowly remove the venous clamp, at the same time increasing arterial flow to maintain satisfactory mean blood pressures and reservoir level.
• Once full estimated flow is reached announce “full flow” clearly so that the anaesthetist can be permitted to stop ventilation
• Keep a close eye on reservoir levels and maintain above 500mls.
• Immediately after initiating cardiopulmonary bypass, all parameters should be checked and noted on the cardiopulmonary bypass record sheet.
• All purge lines and the sampling manifold should be opened.


The Cardiopulmonary Bypass Record:

• This must be completed throughout the case and should be filed in the patient’s notes, a copy being kept in the perfusion department for reference.
• Prior to the start of bypass the patient data should be entered onto the Cardiopulmonary Bypass Record. The date, operation, surgeon, perfusionist and type of oxygenator plus serial number should all be recorded.
• The heparin dose (300i.u/Kg), prime volume and constituents recorded
• Record the time that bypass is commenced.
• Aortic cross clamp time recorded.
• Time off bypass recorded
• Blood gas results
• All drugs and fluids added to the pump should be recorded. This should include serial numbers of Blood and FFP units used.
• The perfusion department diary must be completed for each case. Details should include
1. A patient addressograph,
2. The case record number,
3. The procedure performed
4. The oxygenator type and serial number
5. The HLM used
6. Type of cardioplegic solution employed.
7. The surgeon
8. The anaesthetist
9. The perfusionist
• All details must be entered onto the PATS system before the patient leaves theatre. This also serves as a valuable reference for the completion of the individual perfusionists logbook. Completion of which is required by the College of Perfusionists.



The Management of the Cardiopulmonary Bypass:

• Gloves must be worn at all times when involved in the management of the Cardiopulmonary bypass machine
• The perfusionist should have an unobstructed view of the heart-lung machine at all times.
• The perfusionist must be attentive and communicate clearly with other team members at all times avoiding all distractions.
• The perfusionist should never leave the heart-lung machine unattended at any time.
• The field of work should be clear.
• All waste should be segregated and disposed of into the correct receptacles, i.e. paper/packaging into bins, sharps into sharps container.
• Wherever possible, normal physiological parameters will be maintained using pH. stat or Alpha-stat blood gas management, as directed by the Consultant Anaesthetist in charge. (See Appendix 4) All measurements will be recorded in mmHg format
 Alpha Stat: - 370C.
 Ph Stat: - Temperature corrected.
• During the period of the cardio-pulmonary bypass the partial pressure of O2 will be maintained at 200mmHg +/-25mmHg unless otherwise indicated by the surgeon.
• During the period of the cardio-pulmonary bypass the partial pressure of CO2 will be maintained at 40mmHg (+/-5mmHg)
• Venous blood saturation should be >65% during CPB
• Under the direction of the surgeon or anaesthetist, the perfusionist may use vasoactive drugs and/or vaporising anaesthetic gases for blood pressure management.
• Watch for changes in line pressure when the aortic is cross-clamped to ensure that the aortic cannula is not clamped aswell.
• Cardioplegia: blood cardioplegia administered in accordance with the surgeon’s preference.
 Antegrade via a catheter positioned in the aorta proximal to the clamp.
 Retrograde Cardioplegia the cardioplegia solution is administered via a self-retaining balloon tipped cannula positioned in the coronary sinus. The recommended flow rate would be 180-250 ml/min with the pressure recorded being between 25-35 mmHg. Surgeon s should be kept aware of the recorded pressures and flow rates.
 Blood cardioplegia will be administered where required, in conjunction with the protocol of the surgeon.
• Intermittent Cross-clamp Fibrillation: see below.
• Blood gases and electrolytes will be measured at least every 30 minutes, or more frequently where required, using the Blood Gas Analyser which is situated in the theatre, adhering to the standard operating procedure for the instrument.
• Blood gas and electrolyte samples from patients who are inoculation risks, should be handled according to Trust Health and Safety protocol.
• Where the Blood Gas Analyser becomes unserviceable all samples should be sent to the Emergency Biochemistry Laboratory for analysis, following the laboratory protocol.
• During the cardio-pulmonary bypass procedure it is the responsibility of the Perfusionist to maintain adequate levels of anti-coagulation, monitoring the A.C.T. every 20 - 30 minutes, administering further doses of Heparin as and when required.
• Always maintain a minimum reservoir volume of 500mls during CPB the blood level may fall because of loss into pleural spaces, suction systems, systemic vasodilatation and loss into interstitial spaces.
• Watch venous drainage that may be compromised by a kink in the line, incorrect positioning, venous cannula being too small, operating table too low, reservoir too high, or air embolism.
• Venous drainage may also be affected due to the surgeon manipulating the heart, so discussion with the surgeon at this stage is advised.
• It may be necessary to add volume (fluids) to the pump to maintain levels in reservoir so discussion with surgeon and anaesthetist would be prudent.



Arterial Blood Pressure:

• During cardio-pulmonary bypass where moderate hypothermia (340C) is used, the mean arterial blood pressure (exhibited where continuous mode perfusion is employed) should be maintained at 50-80mmHg.
• In cases where normothermic perfusion is employed the mean arterial blood pressure should be maintained at around 70mmHg.
• In patients with documented neurovascular deficiencies, hypertensive or impaired renal function, the mean arterial blood pressure should be maintained at a level >70mmHg at all times.
• Mean arterial blood pressure can be controlled by increasing blood flow or by the use of vasoactive drugs. Overflow may be undesirable due to the increased risk of embolic load and luxury perfusion.
• Venous saturation levels should be monitored and maintained >65%.



Fluid Management:

• The perfusionist is responsible for fluid management during the cardio-pulmonary bypass, hence maintaining an adequate level in the venous reservoir at all times.
• The haematocrit should be maintained at a level ranging between 20% and 30%.
• The perfusionist should consider the addition of crystalloid solutions, colloid solutions, blood or blood products, and hemofiltration in order to maintain adequate levels and HCT throughout.
• For anaesthetic preferences to IV fluids.



The Regulation of Patient Temperature:

During cardio-pulmonary bypass the patient’s body temperature should be maintained in accordance with the instructions of the cardiac surgeon. The point at which cooling is initiated depends on surgical instruction.

Cooling phase:

• During the cooling phase the patient’s temperature may be allowed to drift downwards until the desired temperature is attained (e.g. 34oC). Where lower temperature (32-28 oC) is required active cooling will be necessary.
• At no point during the cooling phase, should the gradient between the water temperature and the blood temperatures, be greater than 15oC.
• Where circulatory arrest is employed using profound hypothermia, adequate time for cooling should be allowed.
• The temperature to which the patient is cooled, the temperature at which the arrest occurs, and the duration of the arrest period is determined by the surgeon.


Re-Warming phase:

• During the re-warming phase the patient’s temperature should be increased gradually, at a rate, which does not exceed 1oC increment over each 3-minute period.
• The patient’s temperature should not exceed 37.0oC. The patient’s temperature is monitored naso-pharyngeal and recorded on bypass chart.
• The temperature of the blood in the cardio-pulmonary bypass circuit never exceeding 39oC at any time. Alarms limits should be set to alarm if temperature exceeds 390C
• The water temperature to the heat exchanger unit should be monitored and adjusted manually, in order to prevent over heating of the patient’s blood/body temperature.
• At no point during the cooling or re-warming phase, should the gradient between the water temperature and the arterial and venous blood temperatures, be greater than 10oC.

Hypothermic Circulatory Arrest:

A technique employed to enable the surgeon to work in a relative bloodless field or to facilitate the removal of arterial clamps to enable surgical access.

• Circulatory arrest will usually be performed at temperatures below 200C.
As a guideline if circulatory arrest is required at temperatures >200C the safe circulatory arrest times are:-
370C - less than 2 mins
280C -10 mins (surgeon should be informed of arrest time at 2 minute intervals).
220C – 20 minutes (surgeon should be informed of arrest time at 5 minute intervals).


• The patient’s venous blood is drained into the venous reservoir, and the venous line clamped when the surgeon indicates adequate drainage.
• The pump blood is then recirculated internally at a rate of approximately 100ml/min
• During the arrest period the patient’s head may be packed with ice by the anaesthetist
• The surgeon should be informed every 10 minutes of arrest.
• The gas flow to the oxygenator should be maintained at 300-400 ml/min with an FiO2 of 40%
• During profound hypothermic circulatory arrest the surgeon may wish to employ retrograde cerebral perfusion.
During retrograde cerebral perfusion the superior vena cava pressures should be monitored, and should not exceed 40mmHg. At temperatures of <200C the retrograde perfusion should be at 500mls per minute with SVC pressures of 20-40mmHg. The surgeon should be informed if these flows or pressures are outside these limits.
• At the end of the circulatory arrest period, the arterial pump is restarted to fill the patient. The venous system de-clamped at the time of adequate filling and cardiopulmonary bypass re- established.
• The patient will then be re-warmed.

Renal Function:

• During the period of cardio-pulmonary bypass the urine should be monitored. An acceptable level would be 1.0ml/Kg/hour.
• Where the output is less, then a stat dose of 100ml. of 20% mannitol may be administered. If this fails to produce the desired effect, the anaesthetist should be informed and the use of diuretics considered.
• Where there is a history of poor renal function or if the patient is hemodiluted, the use of a haemofilter should be considered.


Termination of Cardio-Pulmonary Bypass:

• Cardiopulmonary bypass should be terminated as per the instructions of the surgeon in charge.
• Prior to the termination of bypass the perfusionist should ensure that;

1. All purge lines and the sampling manifold should be turned off.
2. The patient has attained a temperature of 37oC.
3. There is adequate volume in the venous reservoir.
4. Confirm with the anaesthetist that the patient is ventilated.
5. The anaesthetist is prepared for the termination of bypass

• Only when the perfusionist is satisfied that all checks are complete should the termination of bypass be implemented.
• Partially occlude the venous line restricting blood return to the pump. This will allow filling the heart by raising venous pressure. The anaesthetist gently inflating the lungs may aid this.
• As the venous line is occluded, arterial flow is manipulated to maintain safe reservoir levels. Additional fluid may need to be added to reservoir.
• Arterial pump flow is reduced.
• Once the heart is filled and ejecting, the pump flow is reduced to ¼ flow and preparations are made to discontinue bypass.
• The gas flow to the oxygenator may be turned off at ¼ flow prior to the arterial pump being stopped.
• The venous line is clamped and the pump stopped.
• Announce to the surgeon/anaesthetist that the patient is “Off Bypass”.
• Upon the successful termination of bypass, the arterial and venous lines must be clamped.
• The arterial pump is set to re-circulate at approximately 500ml/min.
• The surgeon will ask the anaesthetist to administer Protamine. The anaesthetist should inform the perfusionist that protamine is being infused. The cardiotomy suction must then be turned off and the surgeon informed
• The residual volume in the bypass circuit is transfused to the patient as directed by the surgeon or anaesthetist.
• Once the arterial cannula is removed the blood in the pump may be ‘bagged’ and or ‘chased through’ at the request of the anaesthetist.
• The perfusionist must remain in theatre and the cardiopulmonary bypass circuit should not be dismantled until the chest is closed, thus facilitating the re-initiation of bypass should this be required.


Cleaning and Disposal of Equipment:
• The perfusionist is required to remove all items of perfusion equipment from the operating theatre.
• All unused de-sterilised cannulas must be disposed of.
• The cardiopulmonary bypass circuit is stripped down off the heart lung machine and disposed of in a sealed biohazard bin. This should not be sealed until the swab count has been finalised. The bin is then sent for incineration.
• The heart lung machine and all items of equipment should be thoroughly cleaned. Any faults should be noted and logged before being stored in the perfusion equipment store prior to further use. Any faults should be rectified as soon as possible.
• Any disposable/consumable items, which were used from the theatre stock, should be replaced immediately.
• All non-disposable components must be washed thoroughly, and returned to the Theatre Sterilising Centre department for re-sterilization.


Storage of Equipment:

• All perfusion equipment should be stored in the perfusion department and the heart lung machine moved into the Perfusion Prep Room ready for use again.
• The Blood Gas Analyser must be plugged into the mains as the Uninterruptible Power Supply only lasts for approximately 20 minutes.
• Any battery operated monitors i.e. myocardial temperature monitor, or inline pO2 monitor should be checked for adequate charge. If low-battery indicators are present monitors should be left recharging.


Haemofiltration:

• The use of a haemofilter during cardiopulmonary bypass should be considered when there is excessive circulating volume on bypass, and or an haematocrit of less than 21%, or the patient is hyperkalaemic.
• Prior to the use of the haemofilter discussions with the Consultant Anaesthetist or Consultant Surgeon are advised.
• Two types of haemofiltration can be performed:- Zero Balance Filtration, or Negative Balance Filtration.
• Zero balance filtration would be used where the patient’s Potassium level is greater than 6mmol and urine output is decreased. 1 litre of 0.9% Sodium Chloride can added to the circuit and then removed via the filter. This can be repeated to help lower the circulating Potassium.
• Negative balance filtration can be used when there is excessive volume in the reservoir and reduced haematocrit (<21%) The removal of the filtrate helps to concentrate the circulating haematocrit.
• Before using the haemofilter the integrity of the outer package must be checked along with the sterilisation date.
• The Arterial side (marked RED) of the haemofilter should be connected to the ¼” connector in the recirculation line, and the Venous side (marked BLUE) should be connected to one of the luer connections on the top of the reservoir.
• The flow through the haemofilter should then be started, with the outlet filtrate line clamped for approximately one minute while the filter is primed. Pre-rinsing is not required.
• As Arterial blood flow has now been re-directed back into the reservoir and not into the patient, the main arterial pump should compensate for this.
• Periodic clamping of the filtrate line can be performed to ensure proper blood flow through the haemofilter.
• Care must be taken not to over-filter the patient i.e. over-concentration (Hcts >32%), and or hypovolaemia.
• Before terminating bypass, flow through the haemofilter should be stopped at the arterial side.
• Post bypass the residual volume in the pump can also be filtered depending on the wishes of the Consultant Anaesthetist or Surgeon. The pump speed should not exceed 500ml/min, and the line pressure in the circuit should be monitored at all times.
• The amount of filtrate in the bag at the end of the procedure should be measured, and recorded on the perfusionist’s bypass chart.


Off Pump Coronary Artery Bypass Surgery:

• When an ‘off-pump CABG’ is scheduled to take place the perfusionist concerned with that case should treat it as an On-Pump CABG. The pump should be set-up and primed as normal, and cannulas required for the operating surgeon should be present in theatre.
• It is up to the perfusionist to supply the scrub staff with the required disposable retractor for ‘Off-Pump’ cases.
• The patient details should be obtained i.e. patient history, and demographics etc.
• The heart-lung machine should be present in theatre in a ready state for Cardiopulmonary Bypass throughout the ‘Off-Pump’ procedure.
• The pump tubing is not passed out on to the table unless conversion to an On-Pump procedure is required.
• If the procedure remains ‘off-pump’ the perfusionist involved in the case should operate the Cell Saver (see page XXX) if requested by the Consultant Surgeon.
• If at any time the procedure has to be converted to an ‘On-Pump’ case the cell- saver should be left immediately and the perfusionists normal duties performed.
• The perfusionist and their equipment should be present in theatre at all times during the ‘Off-Pump’ procedure, until such time as the operating surgeon specifies otherwise.
• The perfusion diary should be completed without numbering it as a ‘Bypass Case’.


Retrograde Cerebral Perfusion:

• This involves perfusion of the head via an arterio-venous shunt/bridge and drainage via suction of the carotid arteries.
• Either:
• Set up an a-v bridge at the pump side of the circuit using relevant tubing.
• Or:
• An arterio-venous shunt is built in the table-pack between the aortic line and the SVC cannula, using sterile tubing. If the jugular vein is to be cannulated for RCP a bridge is connected between this and the arterial line.
• Once the patient has been cooled to the required temperature (as per surgical request) and arrest is started, RCP can be initiated.
• Recommended flow rates for RCP- 200-300mls/min.
• Pressure- ideally below 25mmHg (or as surgical request).
• Time the procedure.


Massive Air Embolism:

• Turn off pump immediately and clamp arterial and venous lines.
• Place patient in Trendelenberg position.
• Disconnect arterial cannula from arterial tubing.
• Compress carotid arteries.
• Remove air from aorta and cannula.
• Refill arterial line tubing with fluid.
• Determine cause of accident and correct. Ensure oxygenator gas vent is unobstructed.
• Place venous cannula in SVC and begin hypothermic retrograde perfusion. Continue whilst venting the aorta for up to 5 minutes.
• Pack the Head in ice and give Phenobarbital.
• Discontinue retrograde perfusion and restart antegrade bypass with 100% oxygen.
• Administer vasopressors to maintain high perfusion pressures.
• Administer steroids after consultation with the Anaesthetist.



Oxygenator Failure:

Signs of failure:
• Falling arterial PO2 or falling venous sats in the presence of 100% FIO2, and flows at normal to high cardiac index and adequate anaesthesia.

Action:
• Ensure that oxygen lines are connected through the entire circuit (from wall, to blender, to oxygenator).
• Check the O2 analyzer to ensure the blender is delivering the proper FIO2.
• Change out oxygenator.


Water to blood leak

Sign of leak:
• Unexpected rise in volume. Ensure that increased volume is not as a result of suction.
• Decreasing pH
• Decreasing hematocrit.
• Haemolysis with hemoglobinuria.

Action- change oxygenator.


Emergency Changeover of Oxygenator

Reasons:
• Oxygenator failure- inability to oxygenate.
• Oxygen leaking blood- i.e. blood to air leak.
• Heat exchanger leak- water to blood leak.


Changeout Procedure

• Notify surgeon of the problem, and assess the stage of the procedure.
• Obtain an oxygenator, arterial pump boot and sterile scissors or blades. Attach the boot to the oxygenator and clamp the reservoir outlet. Prime with 1000mls of Hartmann’s solution and 10000 IU heparin.
• If the patient is still at a hypothermic temperature (moderate or deep), keep cold, or cool further. If warm, stay warm and assess whether the patient is warm enough to come off bypass. Discuss this with the present clinicians.
• Remove suction lines, water lines and clamp and cut (with aseptic technique) the cardioplegia line off, or disconnect (if applicable). Remove the recirculation line from the reservoir inlet also.
• Come off bypass, clamp the arterial and venous lines and “start the clock”.
• Remove the gas line.
• Double clamp the arterial outlet of the oxygenator and the venous line, cut between the clamps with sterile scissors (or blade).
• Remove the pump boot from the raceway and lift the oxygenator from the holder.
• Replace with the new oxygenator and fit the pump boot in the raceway.
• Connect the oxygenator outlet to the arterial line, reconnect the recirculation line to the reservoir, and connect the cardioplegia line (if applicable).
• Unclamp the reservoir outlet and start to recirculate at a suitable flow (say 1-2 lpm) to de-air the circuit.
• Whilst recirculating, reconnect the gas line, the venous line, and the relevant suction lines.
• Once satisfied with de-airing, clamp the recirculation line and resume bypass.
• Once on bypass reconnect the water lines. This can be done now to minimise the time off bypass.


Hard Shell Reservoir Failure:

The procedure to change a blocked or faulty hard shell cardiotomy will depend on:-
• whether it is separate or integral to the oxygenator.
• Replacement of a separate cardiotomy may be considered straight forward, with suction being only temporarily absent while the cardiotomy is changed.

Steps for change-out

• The use of an integral cardiotomy, involves firstly terminating bypass due to interruption to the venous drainage, while the cardiotomy is changed.

In the event of a blocked / faulty cardiotomy:

• The relevant personnel are informed.
• The venous line is clamped.
• The remaining reservoir level is carefully transfused (down to the safe minimum level) to the patient.
• The arterial pump is switched off.
• The arterial line clamped and all suckers are switched off.

The following are then double clamped:
• The outlet from the reservoir to the pump head.
• The venous line to the reservoir.
• These lines are then cut, while suction, recirculation and arterial filter purge lines together with the fluid giving set can be removed and kept sterile.
• The hard shell cardiotomy is then detached from the oxygenator, removed and a new cardiotomy (which has already been checked) inserted.
• The venous inlet, reservoir outlet, suction line, recirculation line and arterial filter purge line are all reattached.
• Volume is added to the newly established cardiotomy.
• The recirculation line is opened.
• The clamps on the reservoir outlet are removed and any bubbles that have entered are removed.
• Bypass may then be reinitiated following removal of venous and arterial clamps.



Intra-Aortic Balloon Pumping
• Prior to use of the Intra Aortic Balloon Pump the manual should be read and made familiar with.
• Also manuals provided with each individual balloon catheter and insertion kit should be read.
• Before proceeding to the area of insertion, check that the following items are present on the balloon pump:-

 3-lead ECG (with pads)
 Slave lead
 Monitoring cable
 Disposable transducer (checking packaging and expiry date)
 Pressure bag
 Transducer holder (on IABP stand)
 500ml Heparinised Saline (checking package and expiry date)

• Next, ensure that there is ample helium in the cylinder by turning the valve fully anti-clockwise. The gauge should read >25% before proceding, if not the cylinder should be changed.
• The disposable transducer should then be flushed through with the HepSaline and the pressure bag pressurised to 200mmHg. The transducer should be mounted on the holder and attached to the balloon pump with the monitoring cable.
• If the height of the patient is not known the 3 different sized sized catheters with insertion kits (34, 40, & 50cc) should then be taken with the balloon pump to the destination, i.e. ITU, CCR, CCU, or theatre.
• The corresponding size for different patient heights are as follows:-

 Patients height <5’4” use a 34cc balloon.
 Patients height >5’4” but <6’0” use a 40cc balloon.
 Patients height >6’0” use a 50cc balloon.

• On arrival at the specified area the 3-lead ECG should be applied to the patient and plugged into the balloon pump.

 Red lead to the front of the right shoulder.
 Yellow lead to the front of the left shoulder.
 Green lead to the patient’s left side.

• The site at which the balloon pump is going to be inserted should then be obtained, either left or right leg.
• The balloon pump should then be plugged into a nearby mains outlet and powered up.
• After the pump system checks have been completed the transducer should then be zeroed. During this time the patient’s height can be obtained and the relevant balloon catheter handed to the scrub staff for opening
• At this point the type of insertion can be discussed with the scrub staff:- sheathed or sheathless.

 Sheathed, if the patient is obese, has had previous cannulae inserted in, or near the insertion site i.e. scar tissue, or the patient is an arteriopath.
 Sheathless if none of the above criteria are met.
• When the balloon pump has finished powering up an ECG should be present on the screen and a flashing diamond should be seen along the trace. The flashing diamond indicates a valid trigger. If there is no ECG trace present, cycle through the different leads, if still no trace, check all lead connections and replace electrodes.
• The ECG trace size can be altered at this point.
• The doctor inserting the balloon should now be trying to locate the femoral artery using the angiographic needle supplied with balloon insertion kit.
• The balloon (still in the tray) should have a vacuum applied to it using the valve and the 50cc syringe. The syringe should be up to 40ml and then removed.
• The stylet running through the monitoring lumen of the balloon should be removed and kept sterile, if angiography is not available to ensure correct positioning of the balloon at the end of the procedure.
• The balloon is inserted using the Seldinger technique, so once the artery is found the guide-wire is inserted through the needle, and the needle removed.
• Next, the first dilator is passed over the guide-wire, inserted into the artery and then retracted.
• If the balloon is to be inserted sheathed then the second dilator should be used, removed and the sheath inserted.
• If insertion is sheathless then the balloon is removed from its tray horizontally, passed over the guide-wire and up into the artery.
• If the balloon is inserted sheathed, after the balloon is inserted into the artery it is connected to the sheath.
• During insertion of the balloon the 2 monitoring lines ( on the catheter tray) are connected with the 3-way tap in the middle, and flushed with Heparinised Saline.
• The flushed monitoring line is attached to the top of the pressure transducer on the balloon pump, and flushed while being attached to the monitoring lumen of the balloon catheter.
• The pressure trace should show an arterial waveform. If the trace is damp, then the monitoring line should be flushed with 10mls of Hepsaline until the trace improves. If it doesn’t the monitoring circuit should be checked (connections) and the positioning of the balloon should investigated by the inserting doctor.
• If no trace is obtained replacement of the disposable transducer should be considered.
• If an arterial trace is still not obtained but a low pressure the doctor inserting the balloon should be notified immediately and the balloon removed. This may mean insertion of the balloon into the femoral vein.
• If a good arterial waveform is observed the balloon catheter should be connected to the balloon pump.
• The positioning of the catheter should be checked either using angiography (if in CCR) or using the stylet (which is the length of the balloon). As the tip of the balloon is radio-opaque if positioning is incorrect the balloon should be moved.
• If positioning is correct the IABP fill button should be depressed for 2 seconds until ‘Autofilling’ appears on the screen. The inserting doctor should be notified that the balloon is being filled.
• After a short period the balloon will be purged of air and filled with Helium. The balloon will then enter a standby state.
• Depression of the standby button will start the balloon augmenting. The start time of augmentation should be noted.
• Fine-tuning of the timing of the balloon should now be set. Changing the frequency from 1:1 to 1:2 will help. Also, highlighting the inflation and deflation phase on the pressure trace will help.
• At this point the augmentation alarm should be set to the desired level.
• Once suitable operation of the balloon is achieved the catheter should be sutured in by the doctor.
• During insertion and operation of the balloon pump any problems that arise should be investigated using the supplied manuals. There is also a help menu available on the balloon pump itself.