Pain Management
Effective pain management can dramatically enhance a rescue effort and minimize morbidity and mortality. Any health care worker providing medical support to a backcountry trip or expedition should be adequately prepared to provide pain relief (Box 24-1). This may be the only therapeutic modality available for the patient.
Evaluation of Pain
The basis of the wilderness pain evaluation should include the following:
Physical Methods for Treatment of Pain
1. An injured extremity is wrapped distal to proximal, with a cloth wrap, rubber Esmarch bandage, or an elasticized (Ace) wrap.
2. Resultant mild anesthesia may occur because of compression of peripheral nerves.
3. If pain increases, discontinue this method.
4. Compression anesthesia may be safe and appropriate in a wilderness setting if other methods or pharmacologic agents are unavailable or contraindicated.
Cryoanalgesia
1. Wilderness cryoanalgesia may be applied with ice, snow, or frigid water.
2. Cryoanalgesia requires a 20- to 30-minute minimum duration for adequate therapeutic effect.
3. Prevention of iatrogenic frostbite and generalized hypothermia while using cold therapy is critical. How long a tissue will tolerate a cold compress before experiencing cellular damage depends on preexisting tissue hypothermia, peripheral versus central nature of the tissue, and temperature and pressure of the cold compress.
4. Cold water immersion may exacerbate injury in persons with snakebite because of venom-compromised tissues.
5. Cold packs are rarely beneficial for marine coelenterate (e.g., jellyfish) envenomations, which may benefit from application of heat (see Chapter 53).
6. Commercial cold packs typically contain a gel of water and propylene glycol, or other similar antifreeze and heat exchange substances, which may be further cooled in cold water or snow to prolong their effectiveness.
7. A reasonable practice is to place a dry, thin cotton cloth or piece of foam between the skin and cold metal cylinders, ice, snow, or cold packs. Remove cold therapy every 15 minutes to assess tissue status.
Heat Therapy
1. Heat application is not usually recommended for initial (up to 48 hours after the injury) pain management of acute trauma because it may lead to increased edema and bleeding.
2. Heat can be used for pain management in the wilderness, especially for patients with chronic pain conditions.
3. Heat applied to the skin of the abdomen may markedly reduce gastrointestinal peristalsis and uterine contractions and thus decrease pain associated with these organs.
4. Application of heat need not be extreme. Temperatures of 37.8° C to 40° C (100° F to 104° F) for 10 to 20 minutes generally provide comfort without creating thermal injury.
5. Heat therapy should be avoided in cognitively impaired persons and for tissue that is anesthetic or ischemic, to prevent further unintended tissue injury.
6. Heat therapy may improve certain marine envenomations. It is generally helpful for spine (e.g., sea urchin, starfish, scorpionfish, stingray) punctures and perhaps also helpful for certain jellyfish stings (see Chapter 53).
7. Liniments and balms are not true heat-transfer agents but consist of multiple botanical or chemical substances that make the tissue feel warm through counterirritant effects and subsequent vasodilation. These substances may help abate a traveler’s soreness and stiffness. Common ingredients include menthol, camphor, mustard oil, eucalyptus oil, methyl nicotinate, methyl salicylate, and wormwood oil. These products are generally only recommended on intact skin with a light cloth or plastic covering and should not be placed on mucous membranes. They should not be used with tight compresses or external heat sources. Topical capsaicin in low concentration is used to relieve pain from arthritis, but its application may cause a marked sensation of skin burning.
Splinting
1. Splints (see Chapter 18) should be well padded to prevent further surface trauma.
2. Splints may be accompanied by pressure dressings or cold compresses for additional pain management.
3. Regular reevaluation of tissue circulatory status is critical to prevent damage from swelling, frostbite, or ischemia in immobile, splinted limbs.
Topical Anesthetics
1. A local anesthetic may provide relief in a topical application before more invasive cleansing and debridement.
2. The local anesthetic EMLA is a mixture of 2.5% lidocaine and prilocaine. After this cream is applied to intact skin under a nonabsorbent dressing for at least 45 minutes, an invasive procedure such as intravenous (IV) needle insertion may be more easily tolerated.
3. Lidocaine gel can also be used for this purpose (Table 24-1).
Table 24-1
Comparable Anesthetic Dosages* for Peripheral Blocks and Local Infiltration
| DOSAGE (mg/kg) | |
| Amide Anesthetics | |
| Lidocaine | 5 |
| Prilocaine | 5 |
| Etidocaine | 4 |
| Mepivicaine | 5 |
| Bupivacaine | 2 |
| Ester Anesthetics | |
| Procaine | 5 |
| Tetracaine | 1-2 |
| 2-Chloroprocaine | 5 |
