Clinically unstable patients with osteomyelitis induced sepsis urgently presenting to the operating room can present the anesthesiologist with many challenges.¹ Cryoamputation, sometimes referred to as “physiologic amputation” or “cryoanesthesia”, does not physically remove the infected limb from the patient’s body, rather it physiologically removes the infected limb from the central circulation prior to surgical removal.² Cryoamputation provides immediate sepsis source control by preventing metabolic byproducts of the ischemic and infected tissue from entering the circulation while providing additional time to clinically stabilize the patient, potentially resulting in reduced morbidity and mortality.³ Although cryoamputation has been described in the surgical literature, there is little information in the anesthesiology literature regarding this approach.⁴ Despite the potential safety benefi ts of using regional or neuraxial anesthesia in avoiding general anesthesia in critically- ill patients, certain patients requiring amputation surgery are too ill for transport to the operating room and require optimization prior to surgery.

Typically, the technique requires 2 tourniquets, dry ice, and an insulated box.² The dry-ice freezes the deep tissues within a few minutes of application to the limb but requires replacement of the ice at least once a day to maintain the frozen state (Figure 1). Measures should be taken to maintain patient normothermia for the rest of the body including warming devices and blankets, especially just proximal to the limb to prevent injury to viable tissue.

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Figure 1. The Dry-Ice Freezes the Deep Tissues

Figure 2 illustrates a limb undergoing cryoamputation. The portion of the limb distal to the tourniquets is placed in dry ice in an insulated cooler (such as a styrofoam box). The portion of the leg proximal to the tourniquets remains protected from the dry ice and warmed to maintain viability. The more distal tourniquet is placed proximal (out of the cooler) to the affected portion of the limb to physically isolate the pathological process from the rest of the body and allow for rapid freezing. The more proximal tourniquet functions to prevent freezing temperatures from migrating more proximally. The 2 tourniquets should be spaced with the minimum amount of distance between them to ensure they both are effectively isolating the patient’s vascular circulation while not compromising healthy tissue. If using a rubber tourniquet, the amount of force applied should lead to an absence of arterial pulse palpation distal to the tourniquet.If using pneumatic tourniquets, the pressure on the tourniquets should be set to 40–80 mmHg above the limb occlusion pressure (to stop the arterial fl ow into the distal limb).⁵ The tourniquets can be the same or different sizes, as long as they are effectively isolating the patient’s circulation and the pathological process from the body.

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Figure 2. A Limb Undergoing Cryoamputation
Used with permission by Somendra Prakash.

Rubber tourniquets are commonly used since they are readily available in this urgent need setting. Medications for pain management are needed in the circumstance that the patient is awake during the freezing period, but are no longer needed as the limb becomes frozen. Clinicians must take proper safety precautions, such as dry-ice specific gloves, to prevent self-injury when managing the patient’s limb or the dry ice itself.

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