--- module: 074-02 language: en chapter: 74 title: "Disaster, Remote, Rural, and Resource-Limited Medicine" module_title: "History, examination, diagnostic strategy, differential diagnosis, and common disease" source_sha256: 1e49b3859c5b69ebe7fe9384346a0aff7e7900d07be8bc36509744b0e5f07565 --- # Austere diagnosis and differential ## Scene, mechanism, and evacuation ### Hazards, patients, help, weather, transport time ### Mechanism predicts hidden injury ### Pre-arrival treatment and exposure effects ### Stable patient may be unsafe to retain #### Deterioration undetectable, no overnight rescue ### Consult retrieval early with a specific question ### Telemedicine cannot create treatment capacity ## Serial physiology as instrument ### Repeated simple observations beat single tests ### Check device values against the patient #### Cold, movement, pigmentation distort oximetry ### Shock before hypotension #### Mental change, cool skin, oliguria #### Children compensate then collapse ### Point-of-care ultrasound depends on operator #### Negative limited scan excludes nothing ## Trauma with limited imaging ### Primary survey, prevent hypothermia ### Reassess after every move ### Head injury without computed tomography #### Declining consciousness strengthens evacuation #### Lucid interval does not guarantee safety ### Chest injury #### Decompress tension without waiting for imaging #### Contusion worsens, early saturation misleads ### Abdominal injury may be occult #### Analgesia should not be withheld ### Fractures: neurovascular checks around splinting #### Compartment syndrome with pulses present ## Environmental illness ### Heat stroke: hyperthermia with brain dysfunction #### Rectal temperature, immediate cooling #### Exclude sepsis, stimulants, serotonin syndrome ### Hypothermia impairs judgement early #### Gentle handling, prolonged pulse assessment ### Altitude illness diagnosed clinically #### Ataxia or confusion: cerebral oedema #### Rest dyspnoea, crackles: pulmonary oedema #### Do not delay descent for imaging ### Envenomation by geography and effects #### Do not capture dangerous animals ## Infection with limited laboratories ### Syndromic assessment #### Epidemiology narrows probability ### Rapid tests lose accuracy in the field #### Repeat negative malaria test if fitting ### Field laboratory quality control #### Only useful when controls work and action changes ### Toxic exposure assessment #### Oximetry misses carbon monoxide #### Responder symptoms reveal ongoing atmosphere ### Outbreaks need denominators and case definitions #### Isolation and sanitation outweigh diagnostics ## Obstetric and paediatric risk ### Pregnancy: gestation, bleeding, pressure, pain #### Ectopic, haemorrhage, cord prolapse need transport ### Birth before retrieval #### Drying, warmth, stimulation, ventilate if apnoeic ### Children dehydrate and cool quickly #### Weight-based drugs and equipment #### Lethargy, rash, caregiver concern lower threshold ## Mental distress versus physical disease ### Stress and grief often understandable responses ### Psychological first aid without forced disclosure ### Confusion may be hypoxia, toxin, glucose ### Direct suicide and violence assessment ## Operational uncertainty ### Document working and dangerous diagnoses #### Record triggers for escalation ### Treatment trials only if failure detectable #### Improvement rarely proves cause ### Discharge needs supervision and return signs #### Do not assume phone coverage or a car