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  • Print publication year: 2015
  • Online publication date: July 2015

6 - Intensive care unit (ICU)

from Section 2 - Intensive care (level 3)



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?

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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.