Consultation-Liaison Psychiatry

Consultation-liaison (C-L) psychiatry involves psychiatric assessment and management of patients in general medical and surgical settings. C-L psychiatrists and trainees are asked to assess patients with acute behavioural disturbance, delirium, adjustment difficulties, suspected psychiatric comorbidity, capacity concerns, and medically unexplained symptoms.

Delirium is an acute neuropsychiatric syndrome characterised by disturbances in attention, awareness, and cognition that develop over a short period and tend to fluctuate throughout the day. DSM-5 defines three subtypes: hyperactive (agitation, combativeness, autonomic arousal — most easily recognised), hypoactive (withdrawal, somnolence, reduced responsiveness — most commonly missed), and mixed. The Confusion Assessment Method (CAM) is the validated bedside screening tool for delirium in non-ICU settings, requiring: (1) acute onset and fluctuating course, (2) inattention, plus either (3) disorganised thinking or (4) altered level of consciousness. Delirium is caused by underlying medical precipitants (infection, metabolic disturbance, drugs, pain, urinary retention, constipation, sleep deprivation, sensory impairment). Management prioritises treating the precipitant and optimising the environment (reorientation, familiar faces, light, noise reduction, mobilisation) before considering pharmacological intervention. When pharmacotherapy is needed for safety, low-dose haloperidol or quetiapine may be used, but benzodiazepines should be avoided (except in alcohol or benzodiazepine withdrawal delirium). NZ ICU delirium rates mirror international figures — approximately 60-80% in mechanically ventilated patients.

Medically unexplained symptoms (MUS) — now increasingly termed functional symptoms or bodily distress — are extremely common in general medical settings (up to 30% of new outpatient presentations). They require a positive diagnostic approach, collaborative explanation, and avoidance of unnecessary investigation or referral cascades.

Psychological responses to physical illness include adjustment disorder (a maladaptive emotional or behavioural response to an identifiable stressor, e.g., a new cancer diagnosis, lasting less than six months after the stressor resolves). Illness behaviour refers to the manner in which people perceive, evaluate, and act on symptoms — excessive or abnormal illness behaviour contributes to disability beyond what organic disease alone would predict.

Capacity assessment in acute hospital settings requires evaluating four domains: does the patient understand the relevant information; can they retain it; can they weigh it and use it to arrive at a decision; and can they communicate their decision? Capacity is decision-specific and time-specific — a patient may lack capacity for one decision but retain capacity for another. In NZ, the Protection of Personal and Property Rights Act 1988 (PPPR Act) governs decisions about adults who lack capacity.