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Cardiac Anesthesiology Made Ridiculously Simple - page 2 / 13

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Consent: Patients having cardiac surgery have serious and frequent complications including: MI 6%, CVA 5%, Neuropsychiatric Effects 90%, Death 1-3-10% (Depends on risk), Transfusion (40-90%), Pneumonia 10%. You must discuss these risks.

Note: Write a clear note with all the standard details and consent. They will get an Aline, PA catheter, TEE. With the computerized records it is easy to get all the patient’s information. Make sure you sign your note so that it is visible to other computer users.

Premedication: These patients are scared. They understand there is real risk. They also will become ischemic with stress. At least 40% get ischemia preop with good premedication. Most will without. Give them oxygen by nasal cannula with some premed: Valium, Morphine, something. Diazepam 10 mg PO on call to OR is a good choice.

Medications Preop: All patients must get their anti-anginals. If the nurses put patient on 9P - 9A BID drugs then state in the chart that patient is to get Drug X, Y, and Z with a sip of water at 6 AM. Otherwise at 9AM they will be in the OR, needing their anti-anginals. Be incredibly clear in your preop orders or they won't get their premeds. Withdrawal of anti-anginal medications during cardiac surgery increases risk of death, MI, CVA, and renal failure. DO NOT DO IT.

PA Catheters: At the present time all bypass cases get the standard monitors plus an a-line, and a pa-catheter. There is an article in JAMA that suggests PA catheters offer little additional information and have inherent risk in ICU patients. As yet, this has not changed our practice. It is clear however that placement of PA catheters must be incredibly skillful without injury to other structures. With no proven benefit all risk must be reduced. One method to achieve this is ultrasonic mapping prior to catheter placement. Remove the towels from behind their head, place the patient in the position you would like, then tape the head in place. Place the patient in tredellenburg. Take a permanent marker and draw out the anatomy, sternocleidomastoid, clavicle, carotid, etc. The more lines the better as it is hard to draw once the ultrasonic goop is in place. Place the blue line in the center of the echo screen. Place the blue dot on the probe to the patient's right. Make sure the probe is absolutely perpendicular to the bed. If you point it at an angle to the bed you will have to take the angle into account and few can do trigonometry in your head. I will be glad to test you on this point. Then take the 5 mHz probe and map out the path of the carotid and the IJ. The IJ is bigger and collapses under pressure, the carotid is round and doesn't collapse under reasonable pressure. If you don't have a line in an appropriate place, wipe off the goop, redraw, and then map again. This technique requires the patient to not move between mapping and placement. I think this system is faster than not using the echo, as you waste 2 minutes mapping, and save 10 minutes of searching with a needle.

Anesthesia: Despite our best efforts we have not been able to demonstrate that one form of anesthesia is obviously better than any other with one exception. Halothane, Enflurane, Isoflurane, high and low dose narcotics, and propofol based anesthetics are equivalent as long as hemodynamics are controlled. Desflurane inductions have been demonstrated to cause pulmonary hypertension and myocardial ischemia. Desflurane is the only anesthetic not recommended for patients with known coronary disease. There is also high dose spinal narcotic (MS 1 mg subarachnoid) but safety data for this technique is limited. During the month you will do two kinds of cases - non research cases during which you should try each of the different techniques to get a feel for them, and research cases with an anesthetic controlled by protocol. With skill, all techniques work, with luck, we may someday know which are truly superior.

Dose Ranges

Fentanyl (High)100-200 mcg/kg (Medium) 20-40 mcg/kg (Low)1-5 mcg/kg

Sufentanyl (High) 20-40 mcg/kg (Medium) 10-20 mcg/kg (Low) 1-2 mcg/kg

Remifentanyl 0.2 to 1.0 mcg/kg/min

Midazolam (High) 3-5 mg/kg (Medium) 2 mg/kg (Low) 0.5 mg/kg

Remifentanyl: To quote one of the great masters of cardiac anesthesia, there are a lot of things that one can do while standing up in a canoe, but why bother? Remifentanyl has a very short half life (5 - 10 minutes) because of its metabolism by non specific cholinesterase. It allows very rapid emergence. It can be used for cardiac anesthesia but the cost is high and some narcotic must be given prior to wake up in the ICU. Reduction in the dose may be possible by giving a longer acting cheap narcotic (fentanyl) to occupy a fraction of the mu receptors and then use the remifentanyl to occupy a smaller fraction. This method of mixing a short half life with a longer half life narcotic may also smooth emergence and prevent accidental emergence should the infusion terminate prematurely. You should try a case with remifentanyl but clearly recognize the dangers and cost of this new drug.

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