The Undifferentiated Altered Mental Status — Written Clinical Reasoning

SAQ 1 — Integrated Management of the Acutely Confused Elderly Patient with Multifactorial Delirium (20 marks, 30 minutes)

Prompt: Outline your integrated management of Mr Chen's acute confusional state, addressing: (a) the ABCDE resuscitation and the immediately reversible causes (the GHOST check); (b) the application of the CAM diagnostic algorithm and the multifactorial model of delirium; (c) the management of the sepsis (pneumonia and UTI) with the appropriate antibiotic regimen in the context of his CKD; (d) the controlled correction of the severe hyponatraemia and the danger of over-rapid correction; (e) the management of the chronic subdural haematoma in a patient on apixaban; (f) the drug review and the medications you would withhold and why; and (g) the common exam trap in this patient. ^[1]

Model Answer

(a) ABCDE resuscitation and the GHOST check (3 marks): ^[1]

The approach begins with the ABCDE, treating life-threats in the order they are found. Airway: patent — he is talking, though incoherently. No intervention needed beyond positioning. Breathing: respiratory rate 22, SpO2 94 per cent on room air — give 2 L of oxygen via nasal speculum to target 94 to 98 per cent (he is not a known CO2 retainer). Circulation: heart rate 96 in atrial fibrillation, blood pressure 104/64, capillary refill 3 seconds — he is mildly hypotensive and peripherally shut down; two large-bore cannulae, send the bloods (including the cultures), and a cautious fluid bolus (250 mL of balanced crystalloid, reassess — the hypotension may be septic or pre-renal, and the CKD and the hyponatraemia caution against over-resuscitation). Disability: GCS 13, pupils equal and reactive, no focal neurology; finger-prick glucose 6.2 (normal — no hypoglycaemia, but the check is mandatory). Exposure: temperature 38.3 (fever), and a full examination for the source of the sepsis (the chest and the urine are already identified as positive). ^[1]

The GHOST reversible-cause check: Glucose 6.2 (normal, checked). Oxygen — give it to target 94 to 98 per cent. Sodium 124 — severe, needs controlled correction (addressed below). Thiamine — give 500 mg IV empirically (he is elderly, possibly nutritionally depleted, and the downside is negligible). Hypertension/hypotension — the blood pressure of 104/64 is low for a baseline hypertensive; address with the cautious fluid and treat the sepsis. ^[1]

(b) The CAM diagnostic algorithm and the multifactorial model (3 marks): ^[1]

Mr Chen meets the CAM criteria for delirium: Feature 1 (acute onset and fluctuating course — acute over four days, from a previously independent baseline), Feature 2 (inattention — he cannot do the months of the year backwards), Feature 3 (disorganised thinking — implied by the disorientation), and Feature 4 (altered level of consciousness — drowsy, GCS 13) ^[1]. The CAM is positive.

The multifactorial model, as described by Inouye, frames delirium as the interaction between a vulnerable patient (predisposing factors — his age, the baseline vascular dementia, the CKD, the polypharmacy) and multiple acute insults (precipitating factors — the pneumonia, the UTI, the hyponatraemia, the AKI, and the subdural) ^[2]. The implication for management is that there is rarely a single cause; there are several, and the workup must address all of them. The dementia is the predisposing vulnerability; the acute change is the emergency; the precipitants are the targets of the treatment.

(c) Sepsis management — pneumonia and UTI with the antibiotic regimen in CKD (3 marks): ^[1]

He has sepsis from two sources: a community-acquired pneumonia (right lower lobe consolidation, fever, CRP 96, WCC 16.2) and a urinary tract infection (positive nitrites and leucocytes). The management is the Sepsis Six bundle — oxygen (given), blood cultures (sent), intravenous antibiotics within one hour, intravenous fluids (cautiously, given the CKD and the hyponatraemia), lactate (measured), and hourly urine output (catheterise if not already). ^[1]

The antibiotic regimen, guided by the local protocol and dose-adjusted for the CKD (creatinine 195, eGFR approximately 30): ceftriaxone 1 g IV daily (no adjustment needed — it is renally excreted but the once-daily dosing is safe at this eGFR) plus azithromycin 500 mg orally daily for three days (for the atypical cover of the community-acquired pneumonia). Add a gram-negative urinary cover if the local guideline requires it (e.g., trimethoprim or nitrofurantoin for the UTI once the culture is available — but these may be contraindicated or dose-limited by the CKD, so I would discuss with microbiology and use the ceftriaxone as the empiric cover for both sources in the acute phase). Paracetamol 1 g IV or orally for the fever. I reassess at 24 to 48 hours with the clinical response, the inflammatory markers, and the culture results. ^[1]

(d) The controlled correction of the severe hyponatraemia (3 marks): ^[1]

The sodium of 124 is severe and is contributing to the confusion and the drowsiness. The correction must be controlled — no more than 8 to 10 mmol per litre in 24 hours — because over-rapid correction risks osmotic demyelination syndrome, the devastating pontine and extrapontine injury first described by Sterns in 1986 ^[5]. The risk factors for osmotic demyelination include the severity of the hyponatraemia, the chronicity, the alcohol use, the malnutrition, and the hypokalaemia — and this patient is elderly and possibly nutritionally depleted.

The approach is the treatment of the underlying cause (the sepsis, the dehydration, the SIADH-like state that can accompany the pneumonia) with cautious normal saline (250 to 500 mL over 4 to 6 hours, reassess) and the serial monitoring of the sodium every 4 to 6 hours. I do not give hypertonic saline unless he seizes or his conscious level falls precipitously — the risk of overcorrection is highest in the patient who is rapidly fluid-resuscitated and whose sodium rises faster than the 24-hour limit. If the sodium rises faster than 10 mmol in 24 hours, I stop the normal saline, give desmopressin and free water to re-lower it, and consult nephrology. ^[1]

(e) The management of the chronic subdural on apixaban (3 marks): ^[1]

The CT head shows a small chronic subdural haematoma on the left (hypodense, no mass effect) — this may be contributing to the confusion, though the sepsis and the hyponatraemia are more likely the primary drivers. The management has four steps: ^[1]

1. Reverse the apixaban. Discuss with haematology — the options are andexanet alfa (a recombinant modified factor Xa that decoys the apixaban) or four-factor prothrombin complex concentrate (PCC). The choice depends on the severity, the local protocol, and the availability. The reversal reduces the risk of further expansion.
2. Neurosurgical consultation. A small chronic subdural with no mass effect may be managed conservatively with serial imaging, but the decision is the neurosurgeon's, and the threshold for surgical evacuation (burr-hole drainage) is lower if the GCS falls or a focal deficit emerges.
3. Hourly GCS monitoring and serial CT. If the GCS drops by 2 points or a new focal deficit appears, repeat the CT urgently and escalate.
4. The fall assessment. How did he fall? Was the fall the cause of the subdural, or was the confusion and the unsteadiness the cause of the fall? Address the underlying contributors (the sepsis, the hyponatraemia, the polypharmacy) and assess for future fall prevention. ^[1]

(f) The drug review — what to withhold and why (3 marks): ^[1]

The drug chart is the highest-yield document in the unexplained delirium, and in this patient several drugs must be withheld: ^[1]

• Gliclazide — withhold immediately. He has an acute kidney injury (creatinine risen from 150 to 195) and the sulfonylurea persists for hours; the risk of prolonged, refractory hypoglycaemia is high. Manage the glucose with a variable-rate intravenous insulin infusion, checking the glucose hourly, and transition back to subcutaneous insulin once the AKI resolves and the glucose is stable.
• Apixaban — withhold immediately, for the subdural haematoma (addressed above).
• Antihypertensives — withhold. His blood pressure is 104/64, which is low for a baseline hypertensive; the antihypertensives will worsen the hypotension, the cerebral hypoperfusion, and the confusion. Restart once the blood pressure is stable and the acute illness is resolving.
• Insulin glargine — continue but adjust the dose for the AKI and the reduced intake. The long-acting basal insulin may need to be reduced; monitor the glucose closely.
• Any other nephrotoxic or sedating drugs — review and withhold as indicated. ^[1]

(g) The common exam trap (2 marks): ^[1]

The trap in this patient is attributing the acute confusion to the underlying vascular dementia without diagnosing and treating the delirium. The dementia is the predisposing factor (the reduced cognitive reserve that makes the elderly patient more vulnerable), not the explanation for the acute change. The CAM is positive, the precipitants are multiple and identifiable (the sepsis, the hyponatraemia, the AKI, the subdural), and the management is the treatment of the precipitants alongside the non-pharmacological delirium bundle. The registrar who documents "confusion — due to dementia" and does not work the precipitants has failed the patient. ^[1]

The second trap is correcting the hyponatraemia too rapidly. The sodium of 124 is severe and tempting to correct fast, but the rate must be controlled at 8 to 10 mmol per 24 hours. The over-rapid correction is irreversible and catastrophic — the osmotic demyelination syndrome produces a quadriparetic, dysarthric, often comatose patient who does not recover. ^[1]