Meticulous Surgery

Avoiding coagulopathy is a complex subject and is not well understood by many. There is a basic and fundamental biological truth that has to be considered at all times, that is, the human blood is meant to be in its natural environment inside the blood vessels which have a surface lining that is biologically active and friendly to the blood. This lining promotes smooth flow as blood travels through the vessels throughout the entire circulatory system. Once the blood is exposed outside to foreign surfaces there are abnormal changes and degradations to its elements affecting its functions. The use of cardiopulmonary, pumps, tubings, cell savers, suctions, other invasive procedures do just that. Therefore, the less and shorter we use these, the better for the blood. It is important to understand the specific factors during surgery that may contribute to bleeding problem and should be avoided. The following should be avoided and some solutions are suggested:

1. Excessive hemodilution: Hemodilution becomes excessive when there is uncontrolled use of the many fluid sources during the operation, such as: IV fluids by the anesthesiologist, cardiopulmonary bypass prime, cardioplegia solution, fluids given by the perfusionist and additional volume given in the maintenance of BP. The cumulative fluid drops the hematocrit significantly which is not really due to blood loss. Excessive fluid administration also dilutes the patient’s coagulation factors causing impairment of the clotting mechanism, leading to a bleeding tendency that is referred to as “dilutional coagulopathy”. The solutions to this problem are: a) restrict fluid administration by the anesthesiologist and perfusionist, b) small cardiopulmonary bypass prime, c) microplegia myocardial protection technique with the use of the Quest MPS, which has a major impact on limiting cardioplegia fluids, d) use of pharmacologic agents and drugs necessary for hemodynamic stabilization instead of volume administration. Often, vasodilatation is the cause of blood pressure decline rather than true hypovolemia. Of course, hemodynamic stability and optimal tissue perfusions should always be maintained.
2. Procedures that have adverse effects on the blood and coagulation factors: a) spillage of blood in the pericardium and surgical field, b)excessive use of high-pressure suctioning in both cardiotomy and cell saver suckers, c) too much use of ice saline irrigations in the surgical field. All these contribute to adverse effects on the blood coagulation mechanism. Solutions to problems are:
   1. avoid spillage of blood in the surgical field,
   2. set the cardiotomy and cell saver negative pressure suctions to the minimum,
   3. minimize irrigation in the field,
   4. avoid over-reliance on cell salvage. The truth is, if meticulous surgical technique is used and fluids are controlled, there is not much to salvage, due to minimized blood loss and improved hemostasis.
3. Prolonged cardiopulmonary bypass and operative times. Examples: surgical delays; extended cooling and rewarming times when deep hypothermia is utilized. Mild to moderate hypothermia is preferred.

If you follow the above suggestions, you will achieve superior outcomes. This approach enables the surgeon to avoid the faulty thinking or habits epitomized by the philosophy: “Do not worry about the fluids, we can do hemococentration,” or “Do not worry about those bleeders, the cell saver will take care of it.”

Cardiopulmonary bypass supports the entire patient during the period when the actual work in the heart is being done. The system is efficient to maintain controlled flow, adequate pressure and perfusion to the tissues of the body with optimum oxygenation. To fulfill these requirements, the bypass system we use has the following features:

1. Efficient, small prime membrane oxygenator,
2. Centrifugal pump,
3. Small prime, 800 ml total volume of whole system including tubings

The small total prime volume avoids excessive hemodilution. An experienced and knowledgeable perfusion team is an essential part of the team.

Myocardial protection:  One of the greatest advances in cardiac surgery in recent years is in the improvement of myocardial protection with use of cold Potassium (K) cardioplegia. This prevents heart muscle injury during the anoxic period of the operation (aortic cross clamp). At this time, the heart muscle is not getting the usual flow of blood and oxygen. Good myocardial protection allows safe operation since the heart recovers well even with the patients with very poor cardiac function with low ejection fraction (EF). The cardioplegia we use, called Microplegia using the Quest Myocardial Protection System (Quest MPS, Atron Corporation, Allen, Texas), has unique advantages: it provides excellent myocardial protection as well as good control of hemodilution. Essentially, Microplegia consists of cold solution of small volume high concentration of K delivered using the fluid from the bypass circuit as the vehicle.  The Microplegia is delivered antegrade via the coronary arteries and retrograde via the coronary sinus about every 15 minutes. One important detail that ensures good perfusion of the myocardium is to monitor the retrograde coronary perfusion pressure, which is maintained at 30-40 mm Hg.

Total microplegia fluid infusion throughout the whole operation is only about 100 to 150 ml, because the diluent for the very high K concentration used is coming from the cardiopulmonary circuit, made possible by the highly sophisticated mixing function and pump delivery of the Quest MPS. Therefore, no additional fluid is needed, which is a novel idea. In contrast, the standard/conventional way of using cardioplegia by most cardiac surgeons involves using cardioplegia solutions prepared beforehand in one- liter bottles of saline solution with a small dose of Potassium; about three to five liters (1000 ml per bottle) are given for myocardial protection, further aggravating the hemodilution, with adverse effect on the patient’s coagulation function (highly diluted blood does not clot well).

Plan the steps of the operation, avoid unnecessary dissection but with enough good surgical exposure. Practice proper sequencing technique which means doing a step and going to the next seamlessly with efficiency without pausing to admire your work. This helps in cutting down the operative time. Be sure that the valve is properly sized to avoid mismatch. The sutures are precisely placed, the valve is seated properly and the sutures are tied tightly. All suture lines are rechecked several times. Hemostatic glues and sealants may be utilized and were used in some of our patients.

For purposes of Illustration, Here Are Examples of Good Hemostasis 

No Blood Stains in the White Towels (Sternotomy Incision) 

Photo Courtesy of Shannon Farmer

Clean Surgical Field (Aortic Graft Repair)              

Photo Courtesy of Sharo Raissi, MD

In preparation for the operation, the surgeon reviews the X-rays and CT scan of the chest (preferably a 64-slice scan) to evaluate the proximity of the heart to the sternal bone and plan his surgical approach in cutting the bone and dissecting the heart. The surgeon figures out the anatomic considerations by correlating the patient’s chest anatomy. As previously mentioned, the heart is often adhered intimately to the sternum, so care should be exercised and more so in the presence of an enlarged heart. A semi-circular blade electric saw is used very carefully. Once the bone is cut, one side of the bone at a time is now lifted gradually and dissection of the cardiac structures is done patiently with utmost care. Enough dissection is carried out to be able to:

1. Insert the sternal retractor
2. Cannulate for the cardiopulmonary bypass
3. Accomplish the planned operation

It is not necessary to free the whole heart. To avoid bleeding when there is a truly difficult area of exposure, cardiopulmary bypass maybe started as an option for safety. On the other hand, too early start of the bypass prolongs bypass time, which is not desirable.

It is important to know the location of a patent Internal Mammary Graft (IMA) to avoid its injury during the reoperation. A CT angiogram and preoperative selective angiogram localize the IMA and show the proximity to the sternum. The IMA should not be injured because it is important to the blood supply to the heart and can also cause bleeding. The surgeon plans and executes his surgical approach accordingly to avoid this problem.

The anesthesiologist is the other vital player in the OR who works closely with the surgeon and the perfusion team. He is responsible for hemodynamic monitoring and oxygenation throughout the course of the operation. He puts in the monitoring lines, which include arterial line, central venous line (CVP), and Swan-Ganz catheter prior to induction of anesthesia and endotracheal intubation. He also performs transesophageal echocardiogram (TEE) at certain parts of the operation to evaluate cardiac function and verifies the position of the coronary sinus catheter that monitors the pressure during retrograde cardioplegia delivery. In addition, he administers necessary fluids, drugs like Heparin, and later Protamine, and other needed cardiovascular medications

The anesthesiologist, surgeon, perfusionist and nurses must communicate well throughout the course of the operation especially on issues of monitoring, hemodynamic parameters, oxygenation, volume/fluids and drug use.

One other procedure requiring the anesthesiologist to be skilled in bloodless techniques is the practice of acute normovolemic hemodilution (ANH). The anesthesiologist removes a unit or two units of blood (calculated amount depending on the patient) in a proper storage bag prior to Heparin and cardiopulmonary bypass. The removed blood is kept in continuity with the patient’s cardiopulmonary bypass circuit, but not in continuous flow; it has all the coagulation factors intact. It is returned to the patient at the end of the operation for improved hemostatic function. In addition, the returned blood increases the patient’s hemoglobin and hematocrit. This is a very important procedure, when property utilized, in the overall strategy for avoiding blood transfusion.

It is desirable to keep lower BP by using drugs during the periods of sternotomy and cardiopulmonary bypass cannulation. There is some blood loss during at these maneuvers, which can be decreased by keeping the patient’s BP down. The anesthesiologist must control the systolic BP to about 100 mm of Hg during these periods.

Antifibrinolytic Agents: Antifibrinolytic agents are suggested to help improve hemostasis and decrease bleeding using tranexamic acid or aminocaproic acid (Amicar) with similar efficacy.  In the past, Aprotinin (Trasylol) had been used but this drug has been discontinued by the Food and Drug Administration (FDA) because of reports of associated increased in mortality and renal dysfunction (Bayer Corporation withdrew the drug in 2008).