Introduction

There may be another operation in which the anesthetic management affects the outcome more than in flap reconstructions, but I can't think of one. Care in planning and implementation can greatly help the surgeon's chance for a successful operation. Fluid management, hemodynamic management, and temperature management all play significant roles in a successful outcome. The fact that these cases can be quite lengthy only makes the challenge greater in that precise parameters must be maintained for lengthy periods. What follows, then is the beginning of an attempt to get it all down.

Communication

First and foremost, there must be two-way communications between the surgical resident and us to discuss various aspects of management the night prior to the planned procedure. The nature, size, and side of the tumor, planned flap sites, and preferred invasive monitoring sites should all be determined the night before the surgery. As these operations are so lengthy, anything we can do to help speed things along (such as having a plan) will be greatly appreciated by our surgical colleagues.

Room Preparation

Appropriate thoroughness in room preparation pays rich dividends. It is essential that the OR be properly prepared before the patient arrives or the patient will be paying the price for the remainder of the case. When you first arrive (6 AM at the latest), turn the room temperature up to 85 degrees. Be sure you have the following items available

1. Forced air warming blanket blower and full body warming blanket.

2. At least one Hot Line, loaded with a disposable and a blood pump set (the kind where you can pump blood in), and primed with fluid. Turn it on now so the tubing is nice and pliable when we start the case.

3. Both a double lumen CVP kit and a long arm CVP kit. Even if a subclavian central line is plan A, we may need to go to plan B (long arm CVP) if we can't obtain subclavian access within a reasonable time.

4. Pressure transducers for A-line and CVP. with two 75 cm pressure tubing extension (left in package). Depending on the side we put our lines, we may need to extensions to reach the transducers.

5. Adult fiberoptic bronchoscope with video head, if available.

6. Machine: Check your machine! Add a humidifier to the circuit. Get long tubes (two sets). Check both sets of long tubes for a leak. The second set will be passed through a sterile sleeve onto the surgical field. Make sure that this second circuit has been checked for leaks, has a gas sampling line, and has a humidifier wire in place. If we have a humidifier wire on the first circuit, but not on the second, the inspired gas will be warmed without a measure of how warm it is at the patient end, which could potentially result in an airway burn.

7. Table Position: I like to have the table turned 180 degrees at the start of the case to minimize hassles associated with turning as well as the inevitable tangles that occur. Check with your attending before the case start and communicate clearly with the nurses on this issue.

Monitoring

Fluid management is a major focus in these cases. In addition to routine monitors, we elect to place an arterial line and central line. I prefer to place the arterial line awake while the patient is being preoxygenated or topicalized for two reasons. Doing two things at once saves time, and placement may well be easier with the higher, pre-induction blood pressure. Liberal use of local anesthetic and some intravenous narcotic make the procedure painless.

I believe central venous pressure monitoring is justifiable in every case of flap reconstruction of any duration. It provides another tool to judge adequacy of fluid management intra-operatively. Perhaps equally as important is the use of the CVP in the post-operative management. The large amount of fluid administered during the case reenters the circulation during post-op days two and three, possibly resulting in fluid overload and pulmonary edema. Knowledge of filling pressures plays an important role in decision making. I prefer the Cook Double Lumen catheters for this purpose.

Airway

Many patients will require an awake fiberoptic intubation. Don't forget the glycopyrrolate (0.2-0.4 mg). As the operation usually involves both sides of the neck, and the head is extended to allow access by the surgeons, we prefer a nasal rae tube on the side opposite the tumor. This is not time to mess around with inferior equipment, so make sure

1. the image through the bronchoscope is good.
2. that you can easily insufflate oxygen via the suction port.
3. that you can easily inject lidocaine through the suction port without it squirting all over.

After the endotracheal tube is placed (usually with the head in a neutral position) the surgeons will reposition the head (extend). This may result in the endotracheal tube being less deep than was originally intended. Be sure to check for a leak and for appropriate cuff position (I like to ballot the cuff in the suprasternal notch) before the prep begins.

Anesthetic Management

The tendency in these cases is to give a balanced anesthetic consisting of fentanyl, isoflurane, nitrous oxide, and oxygen. However, our ability to give muscle relaxants can be limited by the surgeons' requirement for nerve and muscle function in carrying out their dissection. Furthermore, the magnitude of surgical stimulation can change rapidly during the case, from significant stimulation during traction on the mandible, for instance, to no stimulation while waiting for frozen sections. Inhaled anesthetics can be titrated easily, whereas narcotic, one given, is hard to get back. For these reasons, I prefer an inhalational approach, using narcotic only to smooth out peaks in hemodynamics. Also, at equi-MAC concentrations, isoflurane is more likely to prevent patient movement. The vasodilatory properties of isoflurane also provide at least a theoretic advantage for flap blood flow.

Fluid management is guided by urine output and central venous pressure monitoring. Assuming normal pre-op renal function (age corrected), I titrate fluid resuscitation to keep a urine output of 0.5 cc/kg/hr. Urine output should be measured every 30 minutes. A 250cc crystalloid volume bolus us given if urine output falls below this mark.

References

Cox, R. G. (1989). “The anesthetic management of patients undergoing free flap reconstructive surgery following resection of head and neck neoplasms-- a review of 64 patients [letter].” Ann R Coll Surg Engl 71(2): 143-4.

Inglis, M. S., D. S. Robbie, et al. (1988). “The anaesthetic management of patients undergoing free flap reconstructive surgery following resection of head and neck neoplasms-- a review of 64 patients.” Ann R Coll Surg Engl 70(4): 235-8.

A retrospective study was made of 64 patients who underwent free flap reconstructive surgery following resection of neoplasms, mainly in the head and neck region, over a period of approximately 4 years, from 1983 to 1987, in the Royal Marsden Hospital, London. A brief history of free flap surgery is presented, followed by a description of the anaesthetic technique used, and the results of the study. The various ways in which anaesthetic management may influence the results of surgery are discussed.

The data from a retrospective study of 32 anaesthetics administered for free-flap tissue operations are analysed. We suggest balanced analgesic- dominated general anaesthesia, supported wherever possible by continuous regional block. Special attention is paid to full control over the cardiovascular system and the haemodynamics, including the microcirculation and optimal rheological properties of the blood, as well as metabolic ability. Our results suggest that factors such as adequate infusion therapy guided by central venous pressure and urinary output and strict body temperature control, supplementary use of regional blocks and peri-operative use of dextran 40 (Rheomacrodex) can contribute significantly towards the overall success of free-flap surgery.

The anaesthetic management of patients undergoing free flap transfer is discussed in the light of experience over a 4-year period. There is no single magical factor responsible for the success of this type of operation. But as the whole team has gained experience over the last 6 years, the incidence of vessel spasm and/or occlusion has been greatly reduced and at present is rare. It is therefore unusual for our patients to return to the operating theatre for re-exploration of the free flap that has developed ischaemia.

Epidural anesthesia is an effective means of providing pain control and chemical sympathectomy at the spinal nerve root level. The purpose of this study is to compare the efficacy of the combination of epidural and general anesthesia to general anesthesia alone in patients undergoing free flaps to the lower extremity. A retrospective review of 35 consecutive patients (36 operations) from November of 1988 to November of 1990 undergoing free tissue transfer to the lower extremity was undertaken. Sixteen patients had epidural and general anesthesia, and 19 (20 operations) had general anesthesia alone. There were no significant differences in the age or sex of the patients, the distribution between acute and chronic wounds, or the number of cigarette smokers in the two groups. There were no flap losses in the epidural group (100 percent success) and one major, but nonmicrovascular complication (6 percent). In the nonepidural group, there were one flap loss (95 percent success) and five major complications (25 percent). These included three microvascular complications (15 percent). There were significantly fewer patients with postoperative atelectatic fevers in the epidural group versus the nonepidural group. In this consecutive series of patients, epidural supplementation of general anesthesia for free flaps to the lower extremity was associated with uniformly successful flap survival and a lower rate of microvascular complications compared to general anesthesia alone.