Direct application of cold to a body part can produce temporary anesthesia. For example, Baron Larrey, Napoleon's chief surgeon, reported that soldiers' wounds barely hurt and that amputations were "practically painless" if the limbs were exposed to the cold air. (The ambient temperature at the Battle of Eylau, February 1807, was −28°C [−18.4°F].) Arnott first used ice bags with salt to anesthetize limbs during surgery. In most settings, ice bags are preferable to, and more readily available than, cold exposure, although both work. Cooling also intensifies the action of all local anesthetics.29
In the early 1940s, surgeons at major US hospitals and in the US Navy found that they could perform lower extremity amputations on elderly and unstable patients using ice for intraoperative anesthesia and postoperative analgesia.57
The following method provides complete surgical anesthesia for about 1 hour. The anesthesia is sufficient to perform extremity amputations without pain.58,59
This method is not truly a "freezing" technique, since the temperature of ice is 0°C (32°F), and a body's tissues have a freezing point below 0°C. In addition, a film of water at 0°C, rather than the ice, is in contact with the skin. After the ice has been applied for four hours, the skin temperature measures 20°C.58
Most often used on patients with infected or gangrenous limbs, refrigeration anesthesia has proved to be a safe option in aged and high-risk patients. Patients with ischemic limbs do the best with the technique, since the cooling does not drop their core temperature. (Little of the extremity's cold blood ever circulates. That's why the limb is being amputated.) Using this procedure, the general diabetic status of the patients did not deteriorate, even when the amputations were done through infected areas. The patients did well postoperatively, and they were usually hungry and ate soon after the operation. They generally had no appreciable change in their vital signs during refrigeration, the operative procedure, or postoperatively. Overall, the mortality and morbidity in these patients was reduced at major hospitals that used this method.58
Little adjunctive analgesia is necessary for this procedure. Some protocols routinely administered a narcotic before doing anything. In some cases, narcotics were administered as the leg was being manipulated or immediately after preoperative tourniquet placement, but that was rarely necessary.57,58,60
Nearly all patients experienced pain during only the first 15 to 20 minutes after immersion in the ice pack, before the extremity got numb. After this period, the patient often read, rested, or slept.60
Preparing for Refrigeration
Since the basic idea is to immerse the extremity in ice, a suitable container is needed. For feet and ankles, use a bucket. For more proximal surgery, a metal tank with a removable lid to add ice and a padded hole through which to place the leg is required. (A wooden box or a rubber bag—such as a body bag—can also be used, but these will deteriorate with repeated use.) The metal troughs (Fig. 14-7) have a round padded (with sponges or rubber) opening at their upper end, with a sliding top through which the extremity is inserted. At the lower end of the tank, there is a hole for drainage with a spigot, which can be closed when en route to the operating room.57,60
Sagittal and transverse sections of ice trough. (Reproduced from Kennedy.57)
To prepare the supine patient, first protect his bed with a full-length rubber sheet and place a thin blanket under him for warmth.60 Then elevate the limb and apply three bags of cracked ice to an area just above where the amputation is to occur. Secure them with a dressing; leave them in place for 15 minutes. This is where a tourniquet will be applied. Just before the 15 minutes are up, apply an Esmarch (or other elastic) bandage from above the area of inflammation to the tourniquet site.57,58 Then immediately remove the ice bags, put cotton batting or a bandage over area to protect the skin, and apply the tourniquet.
Wrap rubber tourniquets around the limb twice and secure with a surgical clamp. Some physicians apply two tourniquets, in case one loosens. Once the tourniquet is in place, remove the Esmarch bandage.57 The tightness of constriction necessary to stop circulation differs with the patient, the location on the limb, and other variables. Difficulties seem to be less in the thigh, in spite of its thickness, than in the upper part of the calf, where the main artery is protected between bones.59 It is unclear whether the tourniquet should be placed close to the amputation site, so as to leave the narrowest possible zone of chilled and bloodless tissue, or whether it can be placed higher, for example, above the knee for amputation through the calf.
Immediately after the application of the tourniquet, immerse the extremity in ice. If patients can sit up, those needing amputations of the foot and lower leg can immerse the area in a bucket of ice water and cracked ice. For amputations of the thigh, pack the extremity in finely cracked ice, with the patient lying in bed, and usually in one of the troughs described previously.
Using the trough, place a thin layer of chipped ice (approximately 1 to 2 inches deep) in the bottom. Gently place the leg on the ice, taking care that no sharp pieces pierce the skin. Place the tank as high into the groin as possible, using the padding for protection. Protect the genitals with a bath blanket or Turkish towel. Cover the entire limb with crushed ice (about 150 pounds is sufficient). The ice must extend to 2 inches above the tourniquet. Because of the size and awkward shape of the trough, it is difficult to anesthetize the upper thigh. However, you can form a pouch by pulling a rubber draw sheet through the hole in the upper end and then fill it with ice.57,58,60
Raise the head of the bed by placing small blocks under the bed frame at that end; this tilts the bed and facilitates drainage from the foot of the bed (Fig. 14-8). The bevel in the ice container at the proximal end may be used as a urinal or bedpan.57 Place hot water bottles (120°F[49°C]) around the genitals and along the unaffected leg to protect them from the cold. Use care to prevent burning the patient. Remake the top of the bed with a bath blanket next to the patient.60
Ice-box drainage system. (Redrawn from Van Blarcom.60)
Since the metal tank "sweats," wrap it in a large rubber sheet with a hole connected to a tube going to the bucket at the foot of the bed.60 Completely cover the tank by drawing the large rubber sheet around it.
It is prudent to inspect the limb one or more times 20 or 30 minutes after beginning refrigeration. Blanching of the foot is the rule, especially if the leg was elevated before applying the tourniquet. If any sizable arteries remain open, the foot will be darkly cyanosed, and the tourniquet should be readjusted. Any influx of blood makes for incompleteness or delay of anesthesia.59
The optimum length of preoperative refrigeration varied with the amputation level. In the typically thin, weak patients with arteriosclerosis, the optimum length of preoperative limb refrigeration for amputations at the thigh was 2 to 2.5 hours57–59; for disarticulation at the knee or through the middle of the leg, 2 hours; for the lower half of the leg or the foot, 1.5 hours58,59; and for the metatarsus or the toes, 1 hour.59 The limbs were examined at intervals, and ice was added as necessary.
Bring the patient to the operating room (OR) with the extremity in ice.58,60
When the surgical team is ready, place the patient on the table and unpack his extremity from the ice. Remove the limb from the ice, dry it off, and it is ready for amputation. Do not remove the tourniquet, but prepare the extremity as usual and amputate. If the tourniquet is properly applied and securely fastened and the chilling is continuous to all parts at the correct temperature, there is complete local anesthesia so that the patient is not aware when the nerve is cut or the bone is sawed.59
After removing the limb, ligate the large vessels, remove the tourniquet, and then ligate other small bleeders. It is imperative to use cold instruments and cold normal saline solution in the procedure. About half of the cases are closed without drains. In the face of definite infection, the stump can either be drained or be left open.58
The usual dressing consists of one layer of petroleum jelly gauze across the wound, then a few layers of dry gauze, surrounded by bare ice bags. For example, place one bag beneath the stump and two sloping tent-like bags at the sides to avoid pressure on the limb.59 Pain can usually be controlled with the ice bags and a small bandage over the incision.58
The nurses should prepare the routine postoperative bed for the patient, who is often placed in a semi-Fowler's position immediately. Because no nausea or shock is present, the patient can immediately begin progressing to a normal diet.60
Gradually warm the wound over several postoperative days. One method to raise the temperature is to make the dressings a little thicker each day.59 Another is to apply three ice bags to the stump for the first 24 hours, then two ice bags for the second 24 hours, and one ice bag for the third postoperative day.57
Both the degree and the duration of cooling are entirely empiric, guided by the wound's appearance.59 The warming time for the extremity depends upon the blood supply and the degree of infection present. In the presence of good blood supply, remove the ice bags in 24 hours. Infection increases the time of postoperative thawing.58 Sutures are normally left in for an unusually long time, since healing is slowed proportionally with the low temperature.59
Crossman and colleagues found that no harm was caused by either the duration or the extent of refrigeration. Tourniquet marks were visible for a day or two without significance; neither contractures nor paralysis was seen. Likewise, there was no sign of thrombosis or other damage to blood vessels, and no special tendency to necrosis or infection indicating lowered tissues resistance.59