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6 - Intensive care unit (ICU)

from Section 2 - Intensive care (level 3)

Published online by Cambridge University Press:  05 July 2015

Mazyar Kanani
Great Ormond Street Hospital, London
Simon Lammy
Institute of Neurological Sciences, Glasgow
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Agitation and sedation

Give some causes of acute confusion in the post-operative patient

  • Pain (anxiety and disorientation): all of these can commonly occur in critically ill patients

  • Sepsis: systemic infection, or localised to chest, urinary tract, wound, intra-abdominal, intrathoracic, intracranial collection

  • Glycaemic disturbances: this occurs most commonly with hypoglycaemia, but can occur in hyperglycaemia, e.g. ketoacidosis

  • Metabolic: electrolyte disturbances can precipitate agitation, most commonly hypo- or hypernatraemia

  • Respiratory: a compromise in respiratory function can lead to hypoxaemia and hypercarbia. Usual precipitating causes, apart from a chest infection, include acute pulmonary oedema, pneumothorax, pulmonary embolism, sputum retention and subsequent atelectasis

  • Cardiovascular: low cardiac output state and hypotension from any cause, e.g. bleeding, myocardial infarction, arrhythmia leading to reduced cerebral perfusion

  • Renal: acute kidney injury and hepatic failure can cause the accumulation of encephalopathic toxins to develop, e.g. uraemia. Urinary retention in the elderly can be a causative factor

  • Fluid imbalance: both dehydration and water overload can exacerbate the hyponatraemia due to the fluid retention from the stress response to surgery

  • Drugs: e.g. opiate analgesia, excess sedative drugs, anticholinergics

Which investigations should you perform?

Following a full history and examination investigations include

Bedside investigations

  • Boehringer Mannheim (BM): this rapidly assesses if the capillary glucose is low and this provides a value 7% higher than plasma values

  • Arterial blood gas (ABG) analysis: this determines the base excess and respiratory function, e.g. if hypoxia or hypercarbia is present

  • Electrocardiograph (ECG): for arrhythmias or myocardial infarction that can reduce the cerebral perfusion

Non-bedside investigations

  • Haematology: the full blood count (FBC) needs to be assessed for presence of infection, e.g. leucocytosis, neutrophilia and anaemia

  • Biochemistry: this includes serum electrolytes and base renal function (U&Es), e.g. sodium, potassium, calcium, phosphate and magnesium to correct electrolyte disturbances, and urea and creatinine to help guide fluid therapy. The inclusion of liver function tests (LFTs) helps to determine hypoalbuminaemia

  • Microbiology (sepsis screen): blood cultures, wound swabs, urine and sputum cultures to detect the presence of occult infection

  • Radiology: such as a chest radiograph to detect a chest Infection

What is the purpose of sedation in the critical care setting?

Surgical Critical Care
, pp. 253 - 302
Publisher: Cambridge University Press
Print publication year: 2015

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Royal College of Surgeons of England. Renal failure, prevention and management. In Care of the Critically Ill Surgical Patient (CCrISP®), 3rd edn. London, Royal College of Surgeons of England; 2010: Chapter 9.

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