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1. 2. 3. Guide to the Essentials in Emergency Medicine, 3rd Edition Chapter 1: Altered Mental State Peter Manning; Goh Ee Ling CAVEATS The primary focus of the emergency department (ED) evaluation of a patient with altered mental state (AMS) is as follows: To address easily reversible causes, e.g. hypoxaemia, hypercarbia and hypoglycaemia. To differentiate structural from toxic­metabolic causes since the former require emergent central nervous system imaging, whereas the latter are usually more readily identified by laboratory studies. SPECIAL TIP FOR GPs Always consider reversible causes of AMS that you can initiate treatment for in your office: e.g. hypoglycaemia (oral sugar or IV Dextrose 50%), hypoxaemia (supplemental oxygen), or heat stroke (cooling measures and IV normal saline), before sending the patient to the ED by ambulance. MANAGEMENT Initial priorities See Figure 1 for approach to differential diagnosis of altered mental state. The patient should be managed initially in the critical care area. If a promptly reversible cause of AMS is found, then the patient can be downgraded to the intermediate acuity area. Positive airway control/C­spine restriction of movement. 1. Open the airway and search for foreign bodies. 2. Insert oral or nasopharyngeal airway. 3. Apply stiff collar or manual restriction of movement if history does not exclude trauma. 4. Assessment of airway if patient is comatose: with altered mental state comes the potential for loss of a patent airway. This demands at the very least an assessment of the patient’s airway. If active intervention is required, please reference Chapter 30: Airway Management/Rapid Sequence Intubation. Oxygenation/ventilation. 1. Provide supplemental high­flow oxygen if patient is hypoxaemic. 2. In general, target a pCO2 level between 35–40 mmHg. Cardiac output. 1. Check that there is a major pulse; if not, start CPR! 2. Obvious external haemorrhage should be stopped with direct pressure. Do stat capillary blood sugar. Monitoring: ECG, pulse oximetry, vital signs q5–15 minutes. Start peripheral IV at a slow rate (unless hypoperfusion is present) with isotonic crystalloid. Labs: mandatory for FBC, urea/electrolytes/creatinine, ABG (look for metabolic acidosis and hypercarbia). FIGURE 1 Approach to differential diagnosis of altered mental state Note: CO2 narcosis does not necessarily present with respiratory distress; instead, respiratory depression is usually present. Consider serum calcium, drug screen, serum ethanol, carboxyhaemoglobin level and GXM. AMS cocktail: consider its use in part or whole. Its role is basically empirical reversal of hypoglycaemia, opioid toxicity, benzodiazepine toxicity and Wernicke’s encephalopathy. 1. D50W 40 ml IV if patient is hypoglycaemic, followed by infusion of D10W over 3–4 hours. 2. Naloxone (Narcan® ) 0.8–2.0 mg IV bolus. 3. Thiamine 100 mg IV bolus in alcoholics or malnourished patients. 4. Flumazenil (Anexate® ) 0.5 mg IV bolus. a. Can be repeated within 5 minutes if necessary. b. Do not use empirically unless the history is strongly against a mixed OD. If the patient has been taking cyclic antidepressants or is taking chronic benzodiazepines for fits, unnecessary use of flumazenil may produce intractable fits. 5. If trauma cannot be excluded, consider the use of CT cervical spine Clinical evaluation: the focus is on differentiating structural from toxic­metabolic causes of AMS (Table 1). History: rarely clear­cut; look for clues from patient’s family, friends, belongings and information scene from paramedic/ambulance officer. Examination: brief external assessment of patient searching for stigmata of numerous disease processes. While a head­to­toe examination is important, in AMS pay most attention to a focused neurological examination. TABLE 1 Clues from history and physical examination pointing to causes of AMS Non­structural causes Structural causes Empty pill containers Complained of headache to family/friends prior to AMS Medical diseases, e.g. epilepsy, liver disease, diabetes, etc. History of brain tumour Possible carbon monoxide exposure Trauma Absence of focal neurological signs Presence of focal neurological signs Signs of metabolic acidosis Presence of toxidrome AMS due to suspected structural causes Give supplemental oxygen if SpO2 is <94%. Start IV at a slow rate. Perform CT brain scan. Lower intracranial pressure if indicated. 1. Controlled hyperventilation: works fastest but is typically a bridge to emergency surgery and should be utilised for only a short time. See Chapter 99: Trauma, Head and Chapter 5: Breathlessness, Acute, for details. 2. IV mannitol is useful in conjunction with neurosurgical consult as a bridge to emergency surgency. Dose is 1 g/kg body weight (BW), i.e. BW × 5 mls/kg BW of 20% mannitol solution. 3. Steroids are debatable. 4. Simple measures such as head elevation to 30° (assuming no trauma), treating pain, fits and vomiting are necessary. AMS due to suspected toxic­metabolic causes Key principle is treatment of the underlying cause while maintaining ABCs, e.g. antibiotics in sepsis and electrolyte replacement. Check rectal temperature and consider heat stroke if temp >40°C and taking anticholinergics. If meningitis is suspected, consider early lumbar puncture (after CT head scan). Start empiric antibiotics and antiviral agents before either of the tests together with a neurological consult. Refer to Chapter 68: Meningitis. Disposition Admit all cases of AMS. Admit to ICU those who are intubated or exhibiting haemodynamic instability. REFERENCES/FURTHER READING Song JL, Wang VJ. Altered level of consciousness: evidence­based management in the emergency department. Pediatr Emerg Med Pract. 2017 Jan 2 ;14(1):1–28. [PubMed: 28027458] Huff JS. Confusion. In: Walls RM, Hockberger RS, Gausche­Hill M, eds. Rosen’s emergency medicine: concepts and clinical practice . 9th ed. Philadelphia: Mosby­Elsevier; 2018. p. 132–7. Ley C, Smith C. Depressed consciousness and coma. In: Walls RM, Hockberger RS, Gausche­Hill M, eds. Rosen’s emergency medicine: concepts and clinical practice . 9th ed. Philadelphia: Mosby­Elsevier; 2018. p. 123–31. ROYAL AUSTRALIAN COLLEGE OF GENERAL PRACTITIONERS RACGP Access Provided by: Downloaded 2025­6­28 8:18 A Your IP is 49.188.131.52 Chapter 1: Altered Mental State, Peter Manning; Goh Ee Ling ©2025 McGraw Hill. All Rights Reserved. Terms of Use • Privacy Policy • Notice • Accessibility Page 4 / 4