--- module: 063-01 language: en chapter: 63 title: "Fever, Collapse, Dizziness, Weakness, and Undifferentiated Acute Illness" module_title: "Foundations" source_sha256: 07f7b70ae8a4ca92a6caf9ee0fb22c5a38e976602809e19ddc06a61fa1d132fa --- # Undifferentiated acute illness: foundations ## Orientation ### Undifferentiated symptoms are not diagnoses ### Benign self-limited illness to time-critical failure #### Circulation, respiration, brain, metabolism, host defence ### Stabilise, define, find danger, build mechanism differential ### Repeat examination and treatment response revise probability ## Universal first assessment ### Observe before questioning #### Airway, breathing, perfusion, temperature, consciousness, glucose ### Early electrocardiogram #### Collapse, dizziness, chest symptoms, palpitations, older age ### Pregnancy testing alters almost every differential ### Treat immediate threats while investigating #### Hypoglycaemia, hypoxia, anaphylaxis, seizure, shock, sepsis ### Normal observations after transient illness do not prove safety #### Pre-arrival events, recovery, baseline, recurrence risk ## Fever and temperature ### Fever: regulated rise in hypothalamic set point ### Hyperthermia: unregulated heat accumulation #### No response to antipyretics ### Chills suggest rapid rise, not necessarily bacteraemia ### Serious infection without high fever #### Older, frail, pregnant, immune-suppressed, medicated ### History, exposures, full examination #### Avoid indiscriminate cultures from colonised sites ### Sepsis: organ dysfunction from dysregulated response #### Cultures without delaying antibiotics #### Restore perfusion, oxygen, source control ### Non-infectious fever #### Drug fever may lack rash or eosinophilia ### Hyperthermia syndromes need rapid cooling ### Persistent fever: reassess, not automatic broadening ## Collapse and transient loss of consciousness ### Clarify what collapse meant ### Syncope: transient global cerebral hypoperfusion #### Rapid onset, brief, spontaneous complete recovery ### Patient and witness accounts ### Reflex syncope: pain, fear, heat, standing, visceral ### Orthostatic syncope: inadequate compensation to standing #### Asymptomatic drop, normal test not exclusive ### Cardiac syncope: arrhythmia, obstruction, embolism, pump #### Exertional, supine, no prodrome, family sudden death #### Monitoring duration matches event frequency ### Seizure features: aura, tonic then clonic, lateral tongue bite #### Brief jerks also occur in syncope ### Psychogenic non-epileptic events need positive diagnosis ### Collapse without loss of consciousness #### Older adults: multiple contributors, injury, safeguarding ## Dizziness and vertigo ### Descriptive words are inconsistent ### Classify by timing and triggers #### Episodic triggered, spontaneous episodic, continuous acute ### Brief positional vertigo: benign paroxysmal positional vertigo ### Spontaneous episodes: migraine, Meniere, dysrhythmia, panic ### Continuous vertigo: neuritis or posterior-circulation stroke ### Head-impulse, nystagmus, skew testing #### Only continuous syndrome with nystagmus, trained hands ### Stroke concern features #### Headache, focal signs, vertical nystagmus, cannot stand ### Early CT and MRI can miss posterior fossa ischaemia ## Generalised weakness and fatigue ### Weakness, fatigue, sleepiness differ ### Sudden focal weakness is stroke until assessed ### Ascending, bulbar, respiratory: emergency monitoring ### Localise by examination #### Pain and poor comprehension mimic weakness ### Guillain-Barre: ascending symmetrical, reduced reflexes #### Serial forced vital capacity; saturation falls late ### Myasthenia: fluctuating, sensation preserved ### Botulism: descending, autonomic and pupil features ### Potassium, phosphate, magnesium disorders cause paralysis ### Fatigue without objective weakness #### Select tests from history #### Validate disability, avoid false certainty ## Targeted investigations ### Baseline tests according to syndrome ### Add tests only to answer a clinical question ### Interpret with pretest probability #### Mild abnormalities distract #### Wrong-time troponin, early scan cannot close differential ### Indiscriminate testing causes incidental findings and cascades ### Document why disposition is safe ## Treatment, observation, safety net ### Treat threat while preserving diagnostic information ### Fluids when depleted, not reflex boluses ### Hold contributing medicines with restart criteria ### Observation is an active diagnostic strategy #### Duration, repeat checks, escalation thresholds ### Discharge checks: baseline, function, follow-up owner ### Explain uncertainty, give specific return triggers