Gong ans

1) ketoacidosis on bypass - unpredicted metabolic acidosis in kids


pH = 7.26

pO2 = 128 mHg

pCO2 = 16 mmHg

HCO3 = 7.1 mmol/l


Flow = 2.8 l/m2/min


2) Occlusion and temperature

Roller pump occlusion is never changed when cooling and rewarming, though the higher temperature, the bigger is tubing size.

14. On ECMO

That is pretty fucked up!


Femoro-femoral ECMO if veno-venous.


Start ECMO with 1 lpm, then go upto 4 lpm.
More than 4 lpm causes recirculation (tip-to-tip distance <10cm)


Diffusion type plasma tight oxygenators for ECMO (if not - plasma leakage).


If ECMO is initiated immediately after bypass heparin is usually not given for 12 hours, then begin with infusion of 400 UI/hr or 10 UI/kg/hr up to APPT=60-80 sec.

13. Troubleshooting

Oxygenator failure
Oxygenator failure is rare to see.  If it happens, it may be mostly manufacturing defect.

Anticoagulation and ACT monitoring involve in proper management.  Moreover the care on  adding blood to the prime, additional heparin dose and the technique of priming every area is as important as the other in perfusion.  
Do not ignore any step. Caution and vigilance is required all the time.  Whenever you have a doubt don't hesitate to do an ACT to confirm the appropriateness. Especially while rewarming.  Never have an ACT in borderlines.  Adding a little more heparin can be neutralized with a bit more of protamine. 

Adding albumin or fresh frozen plasma in prime prevents platelet aggregation.  Control your suctions and venting just adequate to empty.  Do not suck too much air in it.  Reduce your suction RPM to minimum when not in use.

Oxygenator failure.

1.         Inform surgeon

2.         Note the time

3.         Obtain assistance.

4.         Decide if unit needs changing.

5.         If so stop arterial pump.

6.         Clamp venous inlet to heat exchanger.

7.         Cut venous inlet and arterial outlet.

8.         Remove oxygenator.

9.       Attach new oxygenator.

10.       Reconnect water, gas and vent lines.

11.       Prime heat exchanger.

12.       Reprime oxygenator via bridge, vents and blood lines.

13.       Check circuit for any remaining air.

14.       Restart bypass. 

Oxygen/air blender failure

In case of blender failure you can use gas from anesthesia machine. Ask anesthetist for 8.5 mm endotracheal tube connector (connected to ventilator) and have a ¼” tube full length, connect one end to your oxygenator and another connect to the endotracheal tube end, this endotracheal tube connector will exactly fit to the outlet of anesthesia machine, by titrating O2 and air mixture the desired concentration of FiO2 you can achieve and also if you need you can deliver sevoflurane also.

NB! Oxygenator can decarbonize even without fresh gas supply.

Power failure.

1.         Inform the surgeon

2.         Note the time

3.         obtain assistance

4.         Initiate manual operation of the pump

5.         Attempt to trace the fault

6.         Establish estimated time of power return

Air in the arterial line.

Air in arterial line runs with the speed chosen by you.

0.55 mls of air per kg of body weight is enough to kill (200 - 300 mls for adults)


1.         Inform the surgeon.

2.         Stop arterial pump

3.         Note the time.

4.         Obtain assistance.

5.         Clamp venous line.

6.         Reprime circuit.

7.         Recirculate via bridge, vents and bleed lines.

8.         Clamp arterial line proximal to bridge and reprime
distal arterial line retrogradely from the patient.

9.         Check circuit for any remaining air.

10.       Restart bypass.

Pump boot rupture.

1.         Inform the surgeon.

2.         Stop the pump.

3.         Note the time.

4.         Obtain assistance.

5.         Clamp arterial and venous lines.

6.         Clamp outlet from venous reservoir and inlet to heat exchange.

7.         Replace pump boot using appropriate tubing and connectors.

8.         Reprime circuit via bridge, vents and blood lines.

9.         Check occlusion.

10.       Check circuit for any remaining air.

11.       Restart bypass.

Hard-shell venous reservoir failure.

1.         Inform the surgeon.

2.         Stop the pump.

3.         Note the time.

4.         Obtain assistance.

5.         Clamp venous and arterial lines.

6.         Clamp outlet of venous reservoir.

7.         Cut venous reservoir inlet and out.

8.         Remove reservoir.

9.         Attach venous inlet and outlet to new reservoir.

10.       Attach venous inlet and outlet to new reservoir.

11.       Reprime reservoir.

12.       Recirculate through oxygenator via bridge, vents and blood lines.

13.       Check circuit for any remaining air.

14.       Restart bypass

Important Points / Tips

12. On Service

Gun oil and transmission fluid.

Important Points / Tips

11. On Urgency

What a lot of things there are a man can do without.

(Socrates)

Careful attention to aseptic technique, laminar air flow in the operating room and security of the dry then wet setup is crucial.

Oxygenators work even being wet for more than three days and they do not grow bugs even after 7 days sitting idle.  I only leave a dry circuit for 30days, but it will be draped and in a locked room and OR and away from traffic.  If you a one man operation this is the only way to go.  I can still set up and have a circuit primed in under 10 minutes but given the stress of prepping under adverse conditions why risk having something misplaced only to hurt the patient?  Is there enough evidence to support this practice?  I say there is and my negative lab cultures and good outcomes and stats prove it. 

Off-pump Coronary Arteries Bypass Grafting

Off-pump CABG can turn from dolce far niente into a...


Sometimes you do not have time to check ACT, so give more than normal dosage of heparin to the prime.
If there got another case to follow ,we then will prime the pump before hand.It is a better way to arrange the OPCAB case to be the first case.
Normally the dry pump will keep for 24 hrs.  

Important Points / Tips

10. On Kids

Michelin baby

Important Points / Tips

9. On Weaning

Gently now, you just wanna kiss the ground, just a little peck, a smooch like you're kissing your sister.

(Madagascar. Escape 2 Africa)

Aortic root venting

Venting using the aortic root needle is performed with the help of Y-piece and normally during CABG. The first tip connected to vent suction tubing, and the other end to cardioplegia tubing.

When venting, the tip to cardioplegia is clamped to prevent plegia solution being suck by the positive pressure of the vent. and when giving plegia, the tip connecting the vent is clamped to make sure the solution fully goes to the heart. 
I usually clamp the branch to the relieve valve to prevent backflow of blood that may reach the filter.

When using aortic root venting, the RPM usually around 60-80 rpm and even less when not much blood coming up.

Angry blood

Priming of  venous tubing with Ringer's solution.

Hemofiltration/Ultrafiltration

Hemofiltration/ultrafiltration is fast becoming the preferred method of autotransfusion in cardiac surgery for ECC circuit salvage post CPB. The benefits of ultrafiltration with Peds are also realized in adults especially when you utilize the hemoconcentrator both during and at the end of the case so you don't lose a drop. This comes at a time when globally hemovigilance has become a priority. We all need to reevaluate the use of allogeneic transfusions and the consequences of using them, and look for constructive, quick, easy, reliable and safe reproducible methods of managing autologous blood and avoid discarding viable and vital native cell fractions.  It just makes too much sense to avoid discarding autologous platelets, blood cells and clotting factors which are readily accepted by the patient for homeostasis. 

It all depends on what you are doing with this volume at the end of the case. How much it is, if your bagging it and give it back to the patient so the proteins are still intact but its a little diluted (as you know its a lot easier to add volume than to take it off), or if you sending it all to a cell washer to save just the RBC's. You would be amazed at the amount of viable cell fractions that actually get discarded to the waste bag of cell washers with every use. 

  

Autologous blood has an extremely important life enhancing value. 

MUF

MUF Rate: 10 - 15 ml/kg

CUF

Zerobalanced ultrafiltration reduced postoperative blood loss, time to extubation and postoperative alveolar-arterial gradient in children, which suggests that these effects are not only the result of water removal, but also removal of inflammatory mediators.

Replacement solution, Schiwa Combi-Pac Bicarbonat-Haemofiltration (Dirinco B.V., Rosmalen, The Netherlands):

sodium 140 mmol/L, potassium 2 mmol/L, calcium 1.75 mmol/L, magnesium 0.5 mmol/L, chlorine 112.31 mmol/L, lactate 3 mmol/L, bicarbonate 32 mmol/L and glucose 1 g/L

Blood flow was maintained at approximately 200 mL/min through the haemoconcentrator and ultrafiltration output was controlled at 40 mL/min/m2.

Important Points / Tips

8. On Myocardial Management

You should give cardioplegia thoughtfully, unless you want to go home late.


Antegrade cardioplegia

Antegrade cold crystalloid and blood cardioplegia infusion during hypothermic cardiopulmonary bypass can impaire the morphologic integrity of the coronary endothelium and induce cardiomyocyte apoptosis.

Retrograde cardioplegia 

C.W. Lillehei, peace be upon him, developed the method of retrograde cardioplegia in 1956.

Philippe Menasche, from Hopital Bichat Claude Bernard de Paris, developed manual-inflating retrograde cardioplegic cannula.

The usual flow of retrograde cardioplegia is 200 to 400 mL/min at coronary sinus pressures between 30 and 50 mm Hg. Higher pressures may injure the coronary venous system while low pressures usually indicate inadequate delivery due to malposition of the catheter or leakage around the catheter cuff, but may indicate a tear in the coronary sinus. Induction of electrical arrest is slower (2 to 4 minutes) than with antegrade, and retrograde cardioplegia may provide incomplete protection of the right ventricle. 

Retrograde approach provides superior cardioplegic delivery to myocardium distal to complete coronary occlusions as compared with the antegrade approach.

Verification of retrograde cardioplegia cannula position with ТЕЕ.

But what occurs during retrograde cardioplegia in the case of occlusion of coronary arteries ostia ? Does all cardioplegia flow through thebesian veins into the body of the ventricle?

The addition of retrograde cardioplegia to antegrade cardioplegia improves overall microvascular perfusion.

Of the total microvascular capillary flow, one third was found to be the contribution of retrogradely delivered cardioplegia.

Оverall enhanced microvascular distribution and perfusion occur when both antegrade and retrograde cardioplegia are used.

Combined cardioplegia

When both antegrade and retrograde cardioplegia are delivered simultaneously (even with greater antegrade delivery pressure), one third of capillary cardioplegic flow is the result of retrogradely delivered cardioplegia.

Continuous blood cardioplegia

Continuous cold blood cardioplegia results in improved ventricular performance and reduced myocardial ischemia in comparison with intermittent administration.

Continuous cold blood cardioplegia results in improved ventricular performance and reduced myocardial ischemia in comparison with intermittent administration.

Continuous antegrade tepid blood cardioplegia infusion could prevent cardiomyocyte apoptosis and preserve the integrity of the coronary endothelium well.

Miniplegia

First developed by Antonio Maria Calafiore from Prince Sultan Cardiac Center.

Quest MPS is "on the fly" technology

Normothermic cardioplegia 

Normothermic blood cardioplegia seems to avoid significant changes in myocardial ischaemic status and consequent oxidative stress.

Normothermic cardioplegia offers enhanced myocardial protection compared with that of hypothermic cardioplegia.

Normothermia is better tolerated by arrested heart.

Warm cardioplegia


Tepid RCBC is considered to protect the myocardium from ischemia-reperfusion injury better than cold or warm blood cardioplegia under retrograde continuous perfusion.

Warm blood cardioplegia is considered to protect the myocardium from ischemia-reperfusion injury better than cold blood cardioplegia under retrograde continuous perfusion.

Says Buckberg, myocardial temperature during blood cardioplegia should not be lower than 20°С, given  myocardial oxygen consumption at this temperature is 0,3 ml/100 g · min (10% от нормального). Но даже при температуре миокарда 10°С oxygen consumption equals 0,14 ml/100 g · min, which is 5% от нормального.

Cold cardioplegia

There are two ways of giving blood cardioplegia by using conducer (which is connected to heater cooler with massive cooling ability) and coil (the coil is then immersed in a bucket of ice with some water to enhance the cold effect).

Сold blood cardioplegia. Water temperature is set at 3oC. Blood to crystalloid ratio is 4:1.The crystalloid component consists of 5 times strength St.Thomas' cardioplegia solution (unbuffered), Harefield Hospital formulation. (84mmol/L K+) IVEX Pharmaceuticals. In the absence of pre-mixed Harefield formula high strength cardioplegia, the solution is mixed consisting of 50ml St Thomas’ cardioplegia concentrate (16mmol [1.193g] K+ in 20ml vial) added to 450ml Ringer’s solution. If requested by the surgeon, when other blood:crystalloid ratios are used, the strength of the crystalloid component and delivery ratios are adjusted accordingly. Rate of delivery is determined by the delivery pressure but is given over a period of 3 minutes where possible. The initial dose of cardioplegia is 30ml/kg. Subsequent doses are 10ml/kg or 15ml/kg, as requested by the surgeon. Repeat doses of cardioplegia are given at 20 minute intervals, or as requested by the surgeon. A blood cardioplegia circuit is added to the heart lung machine in all cases, unless agreed with the surgeon prior to the case. In cases where a blood cardioplegia circuit is not added to the bypass circuit, it is the responsibility of the perfusionist to ensure that alternative cardioplegia (crystalloid) is available.

Repolarization cardioplegia (Robert M. Mentzer)

For high potassium concentration 2 ampoule of sterile cardioplegia solution should be mixed with 30 ml of 8.4% sodium bicarbonate and 500 ml of Ringers lactate. For low potassium concentration 1 ampoule of sterile cardioplegia solution should be mixed with 15 ml 8.4% sodium bicarbonate and 500 ml of Ringer's lactate.

Sterile cardioplegia concentrate contains 16 mmols of both magnesium and potassium chloride and 1 mmol of procaine hydrocloride in 20 ml.

Right coronary artery is a pitfall, it is short and takes off at almost right angle.

The left ventricular veins empty predominantly through the coronary sinus, whereas right ventricular veins have rich networks connecting them to the anterior cardiac vein and thebesian veins. Thus, much of the right ventricle antegrade blood flow eventually drains directly into the body of the right ventricle. Not all antegrade blood flow must traverse capillaries to empty into the heart. Arteriosinusoids may exist, which could allow blood to flow from the coronary arteries through arteriosinusoids directly into the body of the ventricle without first traversing capillaries.

Upon entry into the coronary sinus, cardioplegia solution flows into epicardial veins of both the left and right heart. Solution may then flow across capillary beds into coronary arterioles and then eventually out the coronary artery ostium. Some solution, however, is shunted through venous connections to thebesian veins, which then empty into the body of the ventricles without traversing capillary beds.

Antegrade cardioplegia is delivered at 80 mm Hg and retrograde is delivered at 40 mm Hg. Thus, any capillary capable of being perfused by antegrade cardioplegia should have been perfused on the basis of superior perfusion pressure. If no capillaries were available for retrograde perfusion, this cardioplegia could have coursed from the coronary sinus to epicardial veins to thebesian veins, and into the body of the ventricles without traversing capillaries.

при аресте –  снижается на 90% myocardial oxygen consumption.

With acute regional ischemia, both global and ischemic zone regional systolic function are depressed by antegrade continuous warm blood cardioplegia, whereas retrograde continuous warm blood cardioplegia affords adequate protection of contractile performance. However, a loss of diastolic compliance may result as a consequence of warm retrograde delivery.


Increased susceptibility for ventricular fibrillation and dysrhythmia, and the delayed recovery of the conduction system after hypothermic myocardial protection, are related to temperature-induced changes in vital cellular functions of the conduction tissue in the postischemic period. Both cardioplegic methods provide adequate myocardial protection but normothermic oxygenated blood cardioplegia may accelerate recovery of the heart after cardiopulmonary bypass.

Noncoronary collateral blood flow может достигать 25% при некоторых пороках.

1st dose:  20ml/Kg Warm induction 20 ml/Kg Cold, Pressures = < 100mmhg for Neonates (<30 days old); 2nd dose: 10 - 15 ml/Kg, CP Rate: Start at 5-10ml/kg/min increase to desired pressure (5% of CO)  (Сalifornia).

In patients with moderate or severe ascending aortic retrograde cardioplegia is preferred over antegrade cardioplegia to avoid a sandblasting effect of the cardioplegic solution.

Ironically, Melrose et al initially used blood as the vehicle to deliver high concentrations of potassium citrate in 50-s.

The incidence of myocardial stunning ranges from 20% to 80%, postischemic ventricular dysfunction from 3% to 7%, severe dysfunction in high-risk patients from 15% to 20%, and non-Q-wave infarction and Q-wave infarction from 5% to 7%.

One of the earliest forms of cardioprotection, still used at some centers today, is known as intermittent aortic crossclamping with fibrillation and moderate hypothermic perfusion (30 to 32°C).

Antegrade blood or crystalloid cardioplegia is administered directly into the aortic root at 60 to 100 mm Hg pressure proximal to the aortic cross-clamp by a dedicated cardioplegia roller pump.

The heart usually arrests within 30 to 60 seconds. Delay indicates problems with delivery of the solution or unrecognized aortic regurgitation.

Important Points / Tips

7. On Monitoring

Says Arthur C. Guyton, “More than 99 per cent of all sensory information is discarded by the brain as irrelevant and unimportant”.

Despite the Flynn effect and increase in average IQ, there are still a lot of...

Arterial Pressure

Transducer requires a zero reference at the level of left atrium.

All air bubbles must be cleared from the system to prevent damping and air embolism.

Nasopharyngeal and tympanic temperatures reflect the temperature of the brain and closely track blood temperature because these sites are highly perfused. Rectal and bladder temperatures provide a measure of core temperature only at equilibrium.

patient’s organism is gazing silently at you and at what you are doing

Altitude has an influence on gas partial pressure

run a paired ABG

CO₂ flush to the field

lactic acidemia

P_aO₂ should probably be kept above 150 mm Hg to assure complete arterial saturation. Whether or not high levels (i.e., >200 mm Hg) are detrimental has not been determined.

Hyperglycemia (>10 mmol/L) aggravates neurologic injury and other morbidity/mortality.

there appears to be a fair amount of O₂ consumption going on

Venous to arterial CO₂ difference should be 10mmHg or less

shunting within the membrane or membrane lung edema would be somewhat refractory to increases in oxygen supplied (as with shunting or embolus in the human lung)

Nonosmotic secretion of arginine vasopressin provoked by surgical stress, pain, hypotension, or nonpulsatile perfusion contributes to the development of hyponatremia by stimulating renal retention of free water.

A 2- to 5-mEq/L decrease in the plasma sodium concentration is expected after beginning cardiopulmonary bypass and does not normally require treatment.

Hyperglycemia or excessive mannitol administration causes pseudohyponatremia by decreasing the plasma sodium concentration.

Increasing serum potassium concentration is manifested by peaked T waves, a widened QRS complex, disappearance of the P wave, heart block, and conduction abnormalities that may be life-threatening.

A typical intravenous dose of glucose and insulin for the acute treatment of hyperkalemia is 1 g/kg of glucose and 1 unit of regular insulin per 4 g of glucose administered (160 ml 40% glucose and 16 units for 65 kg).

Hypokalemia may be caused by increased sympathetic tone during nonpulsatile perfusion.

Hypocalcemia decreases myocardial contractility and peripheral vascular tone and is associated with tachycardia.

Perioperative glucose control effects outcome after heart surgery. Aggressive protocols aimed at maintaining normoglycemia with the use of insulin infusions during cardiac surgery and into the early postoperative period lead to a decrease in morbidity (e.g., sternal wound infection) and possibly mortality.

premembrane and postmembrane pressures should be measured

Venous saturation and hematocrit monitoring

For every 10mmHg deviation from a CO₂ of 40, expect a change in pH of 0.08.

Important Points / Tips