Wiley chapter · Review draft (near-prose, 1 to 2 sentences per bullet) · target ~15,000 words
Andre Freire, MD, Department of Emergency Medicine, Montefiore Medical Center / Albert Einstein College of Medicine · email TBD
After reading this chapter the reader will be able to:
An austere environment is defined by the barrier to care, not by distance; the 2024 Wilderness Medical Society guideline chose the word austere over remote precisely because weather, terrain, or altitude can cut a patient off even when help is geographically close (Fink et al., 2024). Four features make these settings hard: limited access to the patient and limited reassessment in transport, environmental exposure that makes the environment a second patient, absent monitoring, and limited capability to rescue a treatment that goes wrong.
Because each of these features strips away a safeguard, a given drug is riskier in the field than the identical drug given beside a monitor and a crash cart. Severe pain itself blocks evacuation, so relief is not a comfort measure added at the end but part of the rescue.
The chapter treats one problem under four constraints. Wilderness is defined by distance and self-sufficiency; altitude adds a hostile physiology that changes both the drugs and the patient's breathing; mass gatherings are defined by patient volume and throughput; and disaster is defined by scarcity so severe that the goal shifts from the individual to the greatest number.
The 2014 guideline told providers to climb a fixed ladder from the lowest-risk agent upward; the 2024 update replaced this with simultaneous selection, applying several treatments at once by clinical discretion (Fink et al., 2024; Russell et al., 2014). Selection is driven first by the environment, then by the cause of pain, the severity, and the clinician's experience. The principle is judgment over recipe, with frequent reassessment.
Rule 1 (mechanism): centrally acting drugs that work on the brain and spinal cord, such as opioids and benzodiazepines, are high risk because they threaten breathing and blood pressure, while peripherally acting drugs such as NSAIDs and local anesthetics are low risk. Rule 2 (route): injected routes reach peak levels fast and so carry fast-arriving harm, while swallowed and topical routes are slower and safer when you cannot monitor.
Pain control is never first; the fixed order is scene safety, primary survey (ABC), secondary survey, then pain control. Severity is tracked on a simple 0-to-10 scale to judge whether treatment worked, not to force a specific drug at a specific score, since forcing treatment at a fixed threshold increases drug-related harm.
No single drug is ideal, but the wish list explains what providers actually carry: compact and lightweight, durable against heat, cold, and abrasion, non-sedating, with a wide safety margin, multiple delivery routes, and no abuse potential. Because nothing meets all six, every kit is a set of tradeoffs, which is why surveyed wilderness providers most often carry oral NSAIDs and acetaminophen and less often oral opioids.
Psychological first aid (the ABCDE aid), splinting, and bandaging are weightless, free, and often as effective as drugs. PRICE (protection, rest, ice, compression, elevation) suits acute injuries and suspected fractures. MEAT (movement, exercise, analgesia, treatment) suits soft-tissue injuries that recover faster with early movement.
Acetaminophen, the NSAIDs (ibuprofen, naproxen, meloxicam, ketorolac), and above all the acetaminophen-plus-NSAID combination form the backbone of austere pain care and often control even traumatic pain without an opioid.
Ketamine at pain dose and opioids by needle-free routes (oral, intranasal, transmucosal) cover the severe pain the backbone cannot reach.
Topical and ophthalmic anesthetics, field infiltration, and nerve and hematoma blocks give strong relief without sedation or respiratory risk.
Intravenous lidocaine infusions (narrow safe window, needs lipid rescue) and transdermal opioids (too slow for acute pain) are not recommended in the field.
| Agent | Route | Pain dose | Ceiling / cap | Key caution |
|---|---|---|---|---|
| Acetaminophen | PO / PR / IV | ≤4 g/day or 60 mg/kg, 4 divided doses | 4 g/day | Liver; caution in alcohol use |
| Ibuprofen | PO | 200 to 400 mg q6h | Analgesic ceiling about 400 mg | Kidney, GI bleed, clotting |
| Meloxicam | PO | 7.5 to 15 mg once daily | none | As NSAID; once-daily suits field |
| Ketorolac | IV/IM | 15 mg IV / 30 mg IM q6h | No better than PO ibuprofen | As NSAID |
| Intranasal fentanyl | IN | 1 to 2 mcg/kg (about 100 mcg adult), split between nostrils | <1 mL/nostril absorbed | Respiratory depression |
| Transmucosal fentanyl | Buccal lozenge | Per product | none | Respiratory depression |
| Ketamine | IV / IM | 0.1 to 0.3 mg/kg IV; 0.5 to 1 mg/kg IM | Stay below dissociative range | Mid-range: dysphoria; IM peaks 12 to 15 min |
| Lidocaine (hematoma block) | Into fracture hematoma | 5 to 10 mL 1% (adult) | 1.5 to 2 mg/kg, plain only | Fast marrow absorption; LAST |
A 34-year-old hiker is two days from the road with a closed but clearly displaced ankle fracture. She is alert with normal vitals, shivering, and cannot bear weight. There is no equipment to start an IV, and the party carries only a small medical kit.
The binding constraint is distance and self-sufficiency: supplies are limited to what was carried, and the common injuries are musculoskeletal and environmental. Cold-driven vasoconstriction sets up the central practical problem of the setting by clamping down the veins.
The "no-vein problem" is real: shivering and cold clamp the peripheral veins, so IV access commonly fails in exactly the patient who needs strong analgesia. Enteral analgesia alone cannot cover the pain of a displaced fracture, which forces the choice between mucosal, intramuscular, and regional routes.
Intranasal fentanyl gives strong relief without a vein. The dose is 1 to 2 mcg/kg, about 100 mcg for an average adult, split between both nostrils. Keep the volume at or below 1 mL per nostril, because a larger volume is swallowed rather than absorbed. The transmucosal lozenge has built-in safety because a sedated patient drops it, while transdermal patches are useless for acute pain because their onset is far too slow.
At pain dose (0.1 to 0.3 mg/kg IV or 0.5 to 1 mg/kg IM) ketamine relieves severe pain while preserving airway reflexes and blood pressure, which makes it the strong analgesic of choice when blood loss is possible. The patience rule matters: an IM pain dose peaks at 12 to 15 minutes, so redosing at minute 8 stacks the patient into the dysphoric mid-range and should be avoided.
Ophthalmic anesthetic drops let a patient with a corneal injury or snow blindness open the eye and take part in evacuation, with no important harm shown for short repeated use under 72 hours. A hematoma block sets a distal forearm fracture with 5 to 10 mL of 1% plain lidocaine, and 1% diphenhydramine serves as a local-anesthetic backup when lidocaine is missing or the patient is allergic.
The dogma that anesthetic eye drops are unsafe is challenged by pooled ED data showing no important harm from a short course. The hematoma block carries a LAST risk because fracture-hematoma blood connects to the marrow cavity and absorbs quickly, so only plain lidocaine at 1.5 to 2 mg/kg is used. IV lidocaine infusion is field-banned: its safe window is narrow and a field report described two patients showing early toxicity signs without lipid rescue available.
A 41-year-old climber at 4,500 m sustains a displaced ankle fracture on descent. He had a headache and slept poorly the night before, and the team faces a two-day carry to lower ground.
Hypobaric hypoxia rewrites pharmacokinetics: because cytochrome P450 oxidation needs oxygen, hepatic clearance slows and drugs accumulate, while dehydration impairs renal excretion. The honest teaching point is that most of this evidence is animal or simulated, with thin human field data, so the correct posture is conservative dosing and named uncertainty rather than false precision (Luks et al., 2024).
High-altitude headache is the commonest pain complaint and may be the first sign of high-altitude cerebral edema, so neurology and mental status must be assessed before the headache is masked. Analgesics treat the altitude headache only; they do not treat acute mountain sickness and they do not treat HACE.
Climbers are frequently dehydrated, and an NSAID layered on a dehydrated kidney raises the risk of renal injury, so NSAID use at altitude carries a caution it would not carry at sea level.
Above 4,000 m, dose conservatively and assume impaired hepatic clearance. Opioids are uniquely lethal here because they suppress both the hypoxic and hypercapnic breathing drives, which can produce respiratory arrest during sleep when no one is watching. Ketamine is optimal because it preserves the breathing drive and supports blood pressure, and a peripheral regional block is the safest strong option of all because it is fully peripheral and does not touch the patient's fragile oxygenation.
Nitrous oxide fails at altitude: its low partial pressure gives poor potency, it fails to vaporize in extreme cold, and an emptying cylinder can deliver a hypoxic mixture. The HACE off-ramp is descent, oxygen, and dexamethasone, which is a different problem from pain and must not be delayed by analgesia.
A 23-year-old man reaches the medical tent at a large music festival with a "twisted right ankle." While being assessed he shouts over the music for the medic to look at his friend, who is confused, agitated, and hot to the touch.
The constraint here is volume and throughput, not distance or hypoxia: a transient field hospital with finite providers and few monitored beds. The objectives are to protect the local health infrastructure, manage volume, maximize throughput, and treat and release, so good pain control doubles as good system management (NAEMSP, 2021).
The core skill is identifying masked threats (heat stroke, a toxidrome, intoxication) hidden inside what presents as a simple pain complaint. Triage points toward whatever gets the patient mobile and out of the tent.
The non-opioid backbone (acetaminophen, NSAIDs, and local anesthetics) handles the large volume of minor injuries. A tiered, mostly needle-free plan, the military triple-option model, scales to crowds: acetaminophen plus an NSAID for minor pain, a fentanyl lozenge for moderate-to-severe pain in a stable patient, and ketamine for the unstable patient, all chosen so they do not consume a monitored bed (Butler et al., 2014).
Opioids are riskier than the minor injuries suggest because alcohol and sedatives in an intoxicated crowd add to respiratory depression, sharpening the central-versus-peripheral rule. Monitoring is limited, and documentation and handoff must hold up under volume.
A 25-year-old woman is trapped under a collapsed concrete floor after back-to-back earthquakes strike outside a major city. Both lower legs are pinned. You reach her four hours in: alert, in severe pain, both legs tense, mottled, and dusky below the pins, sensation fading at the feet. The nearest working hospital is miles away and overwhelmed. You have one other provider, a limited drug kit, no monitor, no free bed, and she will not be freed for at least another hour.
The goal shifts from the individual to the greatest number, which means rationing across staff, supplies, and structure. The signature injury is crush: prolonged compression causes rhabdomyolysis, myoglobin injures the kidneys, and crush syndrome is a leading cause of death after disasters (Sever & Vanholder, 2011).
The crush pattern is a tense, mottled, dusky limb with fading distal sensation after prolonged entrapment. The usual peripheral first-line agent is wrong here, and the reason is renal.
The single most important early treatment is aggressive fluid resuscitation to protect the kidneys, which is not analgesia but shapes it by ruling out the NSAID. Pain is then treated by tier: Tier 1 minor pain gets acetaminophen (NSAID only if not crush); Tier 2 moderate-to-severe but stable gets a fentanyl lozenge with no IV; Tier 3 moderate-to-severe and unstable gets ketamine, which preserves breathing and blood pressure.
For the crushed lower limb a femoral nerve block or fascia iliaca compartment block is close to ideal: it spares opioids, spares the kidney, frees provider time, and needs little equipment. This single tool respects the central-versus-peripheral rule, the crush reversal, and the rationing goal at once.
The RAPID study is a published protocol for a planned 1:1:1 trial comparing standard care (morphine 0.1 mg/kg), a landmark fascia iliaca block, and an ultrasound femoral nerve block, using 20 mL of 0.5% levobupivacaine; a companion paper showed generalist humanitarian providers could learn the blocks in a one-day course (Levine et al., 2016; Aluisio et al., 2016). It defined the question and showed training is feasible, but produced no patient outcomes yet.
The honest evidence gap: nearly all nerve-block evidence comes from rich settings with trained proceduralists and simple single fractures, a population that does not resemble complex, open, crush-type disaster injuries, so the hospital evidence does not transfer cleanly. Two further considerations close the section: opioid stewardship under scarcity, and the moral injury that rationing inflicts on providers.
The chapter closes on one unifying idea: one pain problem, four constraints, one recurring danger (the unmonitored central drug) and one recurring solution (the peripheral, needle-free, or regional technique). A short summary paragraph ties the four settings back to that spine, and the cross-environment matrix (Figure 6) serves as the take-home infographic.