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Syllabus for Cardiac Anesthesia
Tamas Seres, MD


General Introduction

This handout will help you to prepare yourself for the most challenging cases in anesthesia practice. The patients you will take care of are unstable and fragile. In this situation your first meeting with the patient is a very important moment. The history and physical provide vital information about the patient exercise tolerance and co-morbidities. Your anesthesia management is based on the issues addressed in the preoperative evaluation. In cardiac anesthesia the preoperative evaluation must contain laboratory data, echo, stress test and catheterization results besides the usual preoperative information. At this level of training you should combine your preoperative evaluation with your experience and knowledge to formulate an anesthetic plan for the cardiac case. For an appropriate anesthetic plan you have to communicate with your anesthesia attendings and cardiac surgeons effectively. The patient care starts with the discussion of the case with your attending on the previous day. Try to collect as much information as possible about the case for this discussion and focus on the possible issues based on the data and the literature. This first discussion helps you for preparing the OR in an appropriate way and performing an individualized management of the actual patient. Keep in mind that there are different attendings with different ideas about cardiac anesthesia. Although it is sometimes difficult to accommodate to different expectations it will be an advantage in your training to learn different approaches. You have the freedom to chose different elements of different practices and establish your future routine. Whatever you do in the cardiac OR you have to be aware about the patient's vital signs. Even if your attending is in the room you should react as you were alone. During establishing an A-line or central line or doing other things like setting up pumps you should react or tell your attending what medication should be given to keep the BP and heart rate at a certain level. Your patient's hemodynamic stability is your responsibility. You have to know what your attending is doing in the OR. If you were not sure ask him or her. If you do not understand something ask about it. This is the only way to collect the necessary information for your future anesthesia practice. In the following paragraphs you will find vital information for your cardiac anesthesia rotation. It is important to read this handout to make sure you know the guidelines for your rotation. The information here will help you to understand the expectations for excellent evaluation. The elements of your evaluation during this rotation include the followings: Preoperative evaluation including communication with your attending and the surgery team. Preparation of the patient for anesthesia which includes the preparation of OR, plan for placement of monitors, plan for transport to the OR if it is applicable and coordination of every events to start the case in the planned time. Induction and maintenance of anesthesia. You will get your freedom in patient management based on the preparation of the patient and your performance in the OR. The most important skill in the cardiac OR is your awareness about changes in your patients' vital signs. Transport the patient to the SICU. Preparation for the transport, your awareness during the transport and the transition process in the SICU are very important part of the evaluation.

 

Preoperative preparation of the patient

In most of the case you prepare the patient in the holding area. The preparation means H/P and formation of an anesthetic plan. IV line will be started in the holding area. A-line placement can be a team work with your attending. There are different options based on the clinical condition of the patient and the best timing of the case: A-line placement in the holding area A-line placement in the OR: Before the induction your attending is putting the monitors on and you put the A-line in at the same time After induction you put the A-line in and your attending is preparing the central line site for you After induction your attending is putting the A-line in and you put the central line in at the same time If you have any concern about the patient stability please use monitors to check the vital signs regularly. If you decide to use Versed and/or Fentanyl please use nasal O2. The key for the successful A-line placement is a good local anesthesia with Lidocain. You have to know your limits. We cannot spend too long time in the holding area or in the OR with A-line placement. A good communication with the surgeons in this situation is very helpful. They can help to start femoral A-line in the OR. If you transfer the patient from MICU or SICU your preparation should be the same. You should start an appropriate IV line (18-14 G catheter, IV tubing with hand pump and extension). Do not transport a patient without running IV. The IV lines in the ICU-s are regulated by pumps and too slow for us. If you cannot start a new IV line disconnect the volume line of the patient from the pump and establish a running IV with our tubing. Make sure you have Phenylephrine, Epinephrine, Lidocaine and Nitroglycerine syringes with you. If the patient is seemingly unstable you have to be prepared for intubation at any time. Keep in mind: bad things are happening during transport but you can give a chance for survival if you are prepared.

 

In the Cardiac OR Preparation the OR

You have to prepare certain medications in 10 cc syringes in the OR to react to changing situations:

 
Epinephrine 10-16 mcg/ml,
Phenylephrine 100 mcg/ml,
Nitroglycerine 20-50 mcg/ml,
Ephedrine 5 mg/ml
Atropine 0.1 mg/ml
Glycopyrrolate  0.2 mg/ml 
Lidocain 20 mg/ml
Calcium Chloride 1 %
Magnesium Sulfate 2.5-5 g 


Heparin 30,000 U/syringe in two syringes.
Heparin is one of the most important drugs in cardiac anesthesia. One syringe with 30,000 U of Heparin should be available at any time!!! You can save lives if you keep this in your mind. The reason for this is the patient fragility. You should be prepared to go on CPB at any time. Before you start Protamine after CPB you have to be sure you have heparin ready to go!!!!

Drips:
Setup a Baxter pump with a carrier and certain drips:

Sodium Chloride 0.9% 250 or 500 ml
Nitroglycerine 100mg/250 ml setup to 0.1 mcg/kg/min
Epinephrine 4mg/250 ml setup to 0.01 mcg/kg/min

When you setup these drips please run them for a couple of minutes to be sure that the pump is actually working. Try to avoid an emergency situation where you nervously try to start an alarming and failing pump. If you felt that either Nitroglycerine or Epinephrine is not necessary for the case please discuss it with your attending but do not change this setup at your convenience. You should have Dopamine, Dobutamine, Milrinone, Vasopressin and Nitroprusside Sodium in the room. In case you have to use them the initial doses are:

Dopamine: 0.5-2 mcg/kg/min for renal dose 3-10 mcg/kg/min for beta receptor effect >10 mcg/kg/min for combined beta and alpha receptor effect  Dobutamine: 5 mcg/kg/min Milrinone: Loading dose: 0.5 mcg/kg or a reduced 2 mg dose. Maintenance: 0.375-0.75 mcg/kg Vasopressin: 0.1 U/min Nitroprusside: 0.1 mcg/kg/min

Monitors

ASA non-invasive monitors.
ECG: 5-lead. Do not forget the 3-lead ECG for the Echo machine.

A-line: usually on non-dominant arm but it can be variable in certain situations.

PAC: R IJ is the usual site to introduce. The second most appropriate site is the L subclavian approach. If both were unsuccessful L IJ, R subclavian or femoral approaches are the choices. Placement of the PAC can be a point of discussion with the surgeon. Patient for ASD closure, tricuspid valve repair, CABG with good LV function do not necessarily need PAC. However, the introducer should be placed in these patients so we can introduce a SG catheter at any time. The other aspect of the PAC is that we have a simple pressure catheter ($ 50) or an oxymetric catheter ($ 250). If the patient is stable and no sign of low CO we can choose the simple pressure catheter.

In case of severe arrhythmias during the PAC placement pull back the catheter to about 20-25 cm leave it there in adjust it after opening the chest with good access to the heart. You can leave the PAC at 20-25 cm in case of severe AS, left main coronary artery disease or left bundle branch block and advance it when the chest is open. A VT period or VF in a patient with severe AS or left main CAD or a complete AV block in a patient with LBBB during the PAC placement can be catastrophic.

TEE: the patient is paralyzed so we do not need bite protector. The probe is placed usually by the attendings but at a certain level of the training the resident can put it in. Certain attendings (Dr Seres) want to place the probe before the establishment of the central line. The rationale is to see the position of the guide wire before the placement of the introducer. If the introducer is going into the carotid artery that artery needs surgical repair.

Heparin

Heparin dose is calculated in the following way: Heparin dose = BW (kg) x 300 (U)

Heparin should be administered slowly because can cause severe hypotension. The effect of Heparin is measured by ACT. The Heparin dose is appropriate if the ACT is >480 sec measured in the presence of celite as an activator of coagulation. If the patient is getting Aprotinin the ACT time is prolonged in the presence of celite because of the inhibiting effect of Aprotinin on the intrinsic coagulation pathway. The Heparin effect should be measured in the presence of kaolin as an activator. Kaolin binds Aprotinin so it cannot alter the Heparin effect on the coagulation. The suggested ACT in the presence of Aprotinin and Kaolin is > 480 to > 650 sec. Certain cardiac surgeon (Dr Fullerton) needs > 650 sec. Sometimes AT III should be administered to reach the demanded ACT level. One vial of AT III is enough in most of the cases.

Antifibrinolytic agents

In our institution two agents are used Amicar and Aprotinin. Amicar is the agent what we use for most of the cases. In off-pump CABG cases none of these agents are used.

Indications for Aprotinin:
Redo cases (relatively big raw surface for bleeding) Heart transplantation (high incidence of severe bleeding)

Consideration:
Predicted long CPB run: double valve cases, CABG and valve cases Concern about coagulation: Aspirin or Plavix use very close to the surgery
          Use of IIb/IIIa receptor inhibitors
          Use of Warfarin before the case
We have to communicate with the surgeons about using Aprotinin. Evaluation of the TEG after induction can help also to decide which agent should be used. Keep in mind that antifibrinolytic agents can cause thrombothic events in certain patients. To avoid stroke, MI or other thrombotic events it is safer to use these agents after Heparin administration. In this way there is much less chance for thrombus formation.

Protocols:
Amicar: You have to order 4 vials (5g each). 5 g is going to the perfusionist for the CPB circuit. 5 g IV from a syringe slowly during 5-10 minutes after administration of Heparin. It can cause severe hypotension. Continuous drip: 2g/hr 10 g in 500 ml Sodium Chloride at the rate of 100 ml/hr or 10g in 250 Sodium Chloride at the rate of 50 ml/hr. This will be our carrier solution and it will run during the CPB.

Aprotinin: You have to order 3 vials (200 ml each). 200 ml is going to the perfusionist for the CPB circuit. Take 2 ml from the second vial and give it IV after administration of Heparin. Wait 2-3 minutes to make sure the patient does not have anaphylactic or severe allergic reaction to this agent. Infuse 200 ml Aprotinin during 30 min (400 ml/hr rate on the pump). Infuse 200 ml Aprotinin at the rate of 50 ml/hr throughout the case. It is stopped usually in the SICU.

Protamine

The dose of Protamine is determined by the perfusionist based on the amount of Heparin was given during the CPB. The calculation is:
          Heparin given during CPB in U/ 100 = Protamine (mg)
Protamine should be administered slowly. Protamine can cause different side effects:
          Transient hypotension (Histamine release )
          Hypotension with increased PA pressure (Prostaglandin release)
          Anaphylactic reaction (IgE mediated)
          Late reaction: hypotension (complement-mediated)
Because of these reactions 1-2 ml test dose should be given to exclude anaphylactic reaction. During Protamin administration Calcium, Epinephrine, Phenylephrine and Nitroglycerine vials should be ready and Heparin should be prepared for CPB. Especially the reaction with prostaglandin release can be so severe that we have to go back to CPB.

Induction and maintenance

In cardiac anesthesia the goal is to keep the patient BP, PAP, HR and CO at the level which is appropriate for the patient clinical condition and heart disease. Different attendings may use different agents but the above goal is the same. If the patient is young and hemodynamically stable, you can plan to extubate the patient in the OR or early in the SICU (fast track extubation). In these cases you have to plan the administration of the narcotics and muscle relaxants very carefully and use a combined narcotic anesthetic gas technique. If the patient is unstable you can plan a high narcotic technique and consider a late extubation. This is an ever changing field so you have to discuss the plan with your attending.

During the case you may do different things (setup pumps, charting, look at the TEE etc.) but you have to be aware of any change in ventilation, oxygenation, BP, PAP, CVP, HR, CO and mixed venous O2 and you should react accordingly. Whenever you see a change, try to find the cause. Do not forget to check the surgical field. Low BP and arrhythmias can be caused by transient manipulation of the heart and they normalize without medications.

Watching the surgical field is necessary for synchronizing the anesthetic management with the surgical steps. Systolic blood pressure should be between 100-110 mmHg just before aortic canulation. After aortic canulation we can ask for volume administration from the perfusionist avoiding big pressure swings. During the placement of the coronary sinus catheter, the manipulation of the heart can cause low BP. After establishing the CPB, you have to be sure that the patient is on full flow before turning off the ventilator. Make sure that he patient has enough narcotics, amnestic agents and muscle relaxants for the CPB.

On CPB

Although this is a relatively uneventful period for us try to be informed about the stage of the surgery and the problems the surgeons have. Keep an eye on the temperature monitors. Make sure that the myocardial temperature probe is working properly and watch the changes in myocardial temperature during cardioplegia. Relatively high myocardial temperatures and/or slow changes may indicate a decreased contractility after the CPB. Long CPB can be a concern also regarding the myocardial function after CPB. In these cases, you should prepare appropriate drips for smooth management. Check the ABG data and react accordingly. In this period the perfusionists control the metabolic status of the patient but you have to play an active role in the patient management. For example you have to check the blood glucose level and administer Insulin accordingly. After removal of the cross-clamp the blood is circulating the heart, so the medications you are giving can reach the heart again. Lidocain, Magnesium sulfate are given at this time to help for restoring sinus rhythm. Low Hb level just before coming off CPB indicates transfusion accordingly. Relatively high K level is usually getting normal after starting the ventilation. Low calcium level should be corrected before coming off CPB usually 15-20 minutes after removal of the cross-clamp.

Coming off CPB

This is a critical period of the management of the cardiac patients. Based on the preoperative data, the events before and during CPB you can plan the anesthetic management during this period. It is a team work with the surgeons also. It is the combination of volume management and BP management using cristalloids, colloids vasoactive injections and drips. This is a typical time when you learn different management patterns from different attendings. In general the goal is to keep the mean arterial BP between 65-70 mmHg, HR: 80-100/min, CO in normal range and PAP, CVP in a range which appropriate in certain contractility states. The ABG should be normal before coming off CPB and should be kept in normal range later. Administration of Protamine is a critical part of this period. Be prepared for extreme reactions as it mentioned in the Protamine part of this handout. The TEE is a very important tool for evaluation of volume status and the myocardial contractility.

Transport to the SICU

During the closing of the skin you have to prepare for the transport process. Try to untangle the infusion tubing and organize them in a way they will be positioned in the SICU (usually on the right side of the bed). Certain attendings (Dr Seres) will ask you to attach the infusion tubing with the manual pump to the central line. The rational of this is that you can give volume and medications very effectively through this line in an emergency situation. Make a smooth transition from the OR monitors to he Propack monitor. Try to minimize the time when the patient is without appropriate monitoring and ventilation. Make sure you have enough fluid volume and medications ready for the transport. Control the BP tightly during the transport and react for every change accordingly.

In the SICU

The anesthesia management is not over at the arrival in the SICU room. You have to check and control the vital signs during the connection to the SICU ventilator and transition from the Propack monitor to the SICU monitor. When the patient is stable and monitored you give the report. The report includes a detailed description of the drips. Let the SICU RN check the drips and have an agreement that the appropriate medications are given in appropriate doses. During this process you still have to check the vital signs and react accordingly. At the end of the report you sign the anesthesia record record the time of the end of the anesthetic management and you transferred the responsibility of he further management to the SICU team.

Summary

Discuss your plan with your attending and you will agree which issues should be discussed with the cardiac surgeons. These issues can be about Amicar versus Aprotinin, handle of implanted pacemaker, AICD or mechanical devices, antibiotic administration in certain allergies, anticoagulation in Heparin intolerance, strategies for A-line, IV line establishment in difficult situations etc. Communication with our surgical colleagues is a crucial point in cardiac anesthesia. They can help us for preparing the patient and our management will help them tremendously.

Examples for using the preoperative data:

Low exercise tolerance: consider low CO. Induction is performed with either Fentanyl or Versed. Do not combine them in these cases because you might induce severe hypotension. Make sure you have Dobutamine and Milrinone solutions in the room.
EF < 30%: same considerations as in low CO syndrome.
Increased creatinine level: consider altered renal function. Think about Mannitol, Lasix and renal Dopamine. Keep BP relatively high.
GERD: consider rapid sequence induction and give at least Bicitra to the patient.
Swallowing problems: meticulous evaluation is necessary to find out possible contraindication to TEE.
Pacemaker is implanted: get the information about the model and ask about EP lab or the company. Get the information how is that particular pacemaker behaves in electrical storms like using electrical equipments on the surgical field? What is happening with the magnet or after defibrillation? Is it necessary to reprogram the pacemaker for surgery or after the surgery?
AICD is implanted: the defibrillator should be turned off and the pacemaker part should be reprogrammed.
Patient has LBBB: introduce SG catheter to 30 cm and leave it there. Introduce it to the final position when the chest is open and the patient is ready for going on bypass any time. You can cause complete AV block and cardiac arrest. It has happened!!!
Patient is on ACE inhibitor (-pril) or on angiotensin receptor inhibitor (-artan): Prepare for severe hypotension make sure you have Vasopressin in the OR.
Left main coronary artery stenosis: keep the BP and HR steady, close to the level at which the patient is living, during induction and maintenance of anesthesia.
Severe 3 vessel disease: keep the BP and HR steady, close to the level at which the patient is living, during induction and maintenance of anesthesia.
Coronary artery occlusion 100%: complete occlusion of any coronary artery can cause steal phenomenon with severe ischemic event. Keep the BP and HR steady, close to the level at which the patient is living, during induction and maintenance of anesthesia.
Severe AS: keep the BP and HR steady. Introduce SG catheter to 30 cm and leave it there. Introduce it to the final position when the chest is open and the patient is ready for going on bypass any time. You can cause VT or VF and cardiac arrest. Cardiac arrest in a patient with severe AS is fatal in most of the case.
Severe AI: bradycardia and hypertension increase the ratio of the regurgitant volume. Keep the BP and HR steady, close to the level at which the patient is living, during induction and maintenance of anesthesia. Avoid bradycardia, prepare Glycopyrrolate to treat low heart rate episodes.
Severe MS: low cardiac output syndrome which can be critical in patient with tachycardia. Keep the BP and HR steady, close to the level at which the patient is living, during induction and maintenance of anesthesia. Prepare Esmolol to treat tachycardia.
Severe MR: bradycardia and hypertension increase the ratio of the regurgitant volume. Keep the BP and HR steady, close to the level at which the patient is living, during induction and maintenance of anesthesia. Avoid bradycardia, prepare Glycopyrrolate to treat low heart rate episodes.
Redo case: These cases have high bleeding risks because of the raw bloody surface after reopening the chest. Prepare Aprotinin for these cases. Make sure that appropriate amount of blood and products are available. Make sure that at least 4 units of blood are checked before incision and at least 2 units are in the OR.