Propofol: You should try a case with propofol used continuously from the start of the case, and one where it is added after bypass. It is expensive but allows a simple technique for early extubation. If early extubation and discharge from the unit is planned the expense of drugs that make it possible is easy to justify.
Dexmedetomidine is an alpha 2 agonist with a 1500:1 alpha 2 to alpha 1 ratio. For example, clonidine has a 30:1 alpha 2 to alpha 1 ratio. It may be used as an adjunct to anesthetics with reductions in MAC or as a post operative sedative by infusion. Its role in cardiac anesthesia is just being figured out.
Planning for Early Extubation: With the health care revolution this is the new thing. The key is multiple little changes in anesthetic technique that make it possible and a good candidate who is problem free to make it work. The problem is simply that many patients appear to be good candidates and then aren’t when they get to the ICU, others look like problems and do well. The simplest solution is to treat all patients as candidates for early extubation and then see who qualifies. Early extubation should be planned for in all patients because it requires planning right from the start of the case. The most successful candidates have reasonable cardiac and pulmonary function but it is certainly not a requirement. The changes we have made include limiting fluid given to the patient. Limiting the total narcotic and benzodiazepine dose. Rely on volatile agents or propofol during the case. Provide sedation post op that is easy to get rid of (propofol). Careful control of blood pressure with emergence. Remember some vasodilators (nitroprusside) inhibit hypoxic pulmonary vasocontriction, increase shunt, and make weaning of FIO2 more difficult. Rapid weaning of FIO2 post op is critical. Then extubate the patient. Extubation time is controlled by nursing shift changes and protocols. If you want to extubate early, wean the FIO2 rapidly, wake the patient up, and when the patient meets written extubation criteria do it. It requires a cultural shift to accomplish. The most common reason for delayed extubation is simply V/Q mismatch (shunt) caused by heparin-protamine complexes in the lung. The second most common reason is excessive sedation. Finally, hemodynamics, coagulopathy, etc. get on the list.
Set Up: Standard room set up including Suction, Machine checkout, Airway equipment, Drugs (Succinyl choline, thiopental, non-depolarizing muscle relaxant, atropine, glycopyrolate, ephedrine, neosynephrine (syringe and infusion ready), dopamine (infusion ready), calcium chloride, heparin (30,000 units drawn up), lidocaine and epi in drawer.
Patient Preparation: At least one large IV ( < 16g), two are better, a-line on right (left side is occluded by retractor for IMA), take into room and place on O2 for rest of setup, 5 lead for machine, 3 lead for echo, cover V5 with tegaderm. Right IJ PA catheter. Preox while getting baseline values.
Intraoperative Safety: Cardiac surgery has large quantities of blood at arterial and higher pressures. There is frequent splash. You must wear eye protection at all times in the operating room. Expensive goggles around the neck are not acceptable. Put them on at all times in the OR. You should consider the operating room as a woodshop with HIV on all the wood chips. You would not operate power tools in a woodshop without eye protection, do not do it in the OR.
Communication: This operation is a long series of repetitive procedures that absolutely, positively, have to be done correctly. If any are done incorrectly the patient will suffer. Communicate with the surgeon. Ask questions. Tell him what you are doing. If you are having trouble, tell him/her. The operation requires a team approach and you are a member of the team. Don't let your activities or problems be a mystery to the surgeons.
Hypotension: The surgeons can cause profound hypotension with cardiac manipulation. If the pressure suddenly drops or PVC's develop look at what they are doing. Before you give a drug to treat episodic hypotension look to see what they are doing. If you give a drug because of hypotension caused by the surgeons and then they let go of the heart, the pressure will sky rocket. State clearly "Pressure is 70/30) they will get the message and stop lifting up the heart. They may ask you to hand ventilate during some dissection. Watch what they are doing to make sure you are helping not hindering.
Prior to Valve Repairs there are specific recommendations:
AS: Preload: Keep it up Afterload: Maintain SVR: Maintain HR: 50-80 Rhythm: NSR
AI: Preload: Keep it up Afterload: Down SVR: Drop HR: 60-80 Rhythm: NSR
MS: Preload: Keep it up Afterload: Maintain SVR: Maintain HR: 50-80 Rhythm: NSR