Referring to the Intensive Care Unit

As a foundation doctor, caring for patients who deteriorate rapidly and/or are critically unwell can be daunting.
Intensive care units provide the highest-level care for patients within the hospital. Knowing which patients are appropriate to refer is important for all foundation doctors to understand.

Critical care outreach teams (CCOT) provide a link between the wards and intensive care. At most hospitals, the CCOT service is run by nurses and other advanced healthcare professionals who are very experienced in assessing and looking after unwell patients.

This article will look at which patients should be referred to ITU, how to refer to ITU and the key information ITU will want to know.

Who to refer to ITU?

ITU is suitable for patients who need more extensive monitoring and invasive treatment than can be provided on standard medical wards. It is usually for patients who have organ failure, which is thought to be reversible. Therefore, the ITU can provide end organ support to facilitate the treatment of reversible disease processes.

Any pre-established treatment escalation plans (TEP) must be read and considered when deciding who to refer to ITU. Whilst some patients may not be for CPR or intubation and ventilation, they may be appropriate for other treatment options offered in ITU, such as inotropes.

There is some overlap between the intensive care unit and other areas of the hospital. Some respiratory wards offer NIV – some renal units offer dialysis. What separates critical care is the ability to offer support for multiple organ systems, or ventilation, plus enhanced nurse:patient ratios.

ITU can support patients who require:

  •  Airway support – e.g. obstruction, GCS <8
  • Respiratory support – e.g. intubation and ventilation, HFNO or NIV
  • Cardiovascular support – e.g. inotropes, bradycardia management
  • Neurological support – e.g. intracranial haemorrhage, status epilepticus
  • Renal support – e.g. refractory hyperkalaemia, acidosis, uraemia, anuria,hyponatraemia

How to refer to ITU?

There are generally 3 ways that intensive care can be informed of, or become aware of, patients:

  1. Critical Care Outreach Teams (CCOT)
  2. Direct ITU referral
  3. Medical emergency team or crash team calls
Critical Care Outreach Teams (CCOT)

Critical care outreach teams (CCOT) can vary depending on which hospital you work at but are usually made up of senior nurses who have backgrounds in ITU, ED or specialist respiratory medicine. They are therefore very experienced in identifying, assessing, and looking after critically unwell patients and subsequently liaising with ITU about potential admission.
They also may make up part of the medical emergency or crash team and follow up on patients who are discharged from intensive care onto the standard wards.
CCOT may be made aware of patients automatically (for example, those scoring above a certain EWS threshold) or by doctors on the ward seeking help with patients they are concerned about.

Direct ITU referral

Referrals to ITU are usually made through the on-call ITU registrar. As an FY1/2 on the wards, you may be asked to make the call but will usually not be alone with the patient – any patient unwell enough to prompt a discussion with ITU, would also warrant senior review and support from the registrar within your team. However, you may be the first to review the patient when they have deteriorated- it is important you can identify those patients who may benefit from ITU and escalate promptly.

Medical Emergency Teams or Crash Team calls

In emergency situations, a 2222 call can be put out. This activates a team of people, which may include a combination of:

  • Medical registrar and/or SHO and/or FY1
  • ITU/anaesthetics registrar and/or SHO
  • CCOT
  • Advanced Practitioners

In the case of a return of spontaneous circulation after cardiac arrest, patients are discussed with ITU for admission for prognostication.

What do ITU want to know?


Your name, grade, what team you are working for. The patient’s name, identifying number (e.g. hospital/NHS number – allows the ITU senior to access their records and results, if you work in a hospital with electronic patient records).

Patient baseline

An intensive care stay puts a huge amount of physiological stress on patients; intensivists demand a lot of patients, whether the physical rigor of interventions or procedures, intensive physiotherapy regimes, plus the metabolic stress of the condition that indicated for intensive care in the first place.

An ICU stay can have many short- and long-term sequelae; patients become generally deconditioned, lose muscle mass, are exposed to often severe and multi-drug-resistant infections, can acquire delirium and other neuropsychiatric complications.

Despite meticulous patient selection, enhanced monitoring, advanced treatment techniques available and more frequent senior medical reviews than anywhere else in the hospital, survival remains in the remit of 50%. Without careful selection of eligible patients, intensivists run the risk of simply prolonging a patient’s death and punctuating it with painful and invasive interventions for no appreciable benefit.

Critical illness invariably impacts that patient’s function. Therefore, the admitting intensivist has to be able to demonstrate a level of physiological reserve that makes the patient likely to survive to discharge with a quality of life or functional level that they would accept.

Patient baseline can be difficult to quantify, but some useful pieces of information are:

  • Clinical frailty scale- this is a ratified tool which closely correlates to survival. It is measured by looking at their level of function in the 2 weeks prior to the illness that brought them into hospital.
  • Exercise tolerance – distance on the flat, and number of flights of stairs they can climb.
  • Level of independence- what are they able to do themself and what do they need help with?
  • Co-morbidities and extent of control- for example, is your patient a brittle asthmatic with 4 previous ICU admissions? Are they a diabetic with no compliance with their insulin?
Admission story

Present this as you would when discussing with any specialty team; their presenting complaint, diagnosis, and course of the admission so far.

Desired Input from Critical Care

Often, an ICU reg will ask the referrer what they want intensivists to provide for the patient – this isn’t meant as an obtuse statement!

Intensivists have access to means of organ support, a team of seniors with training and experience in managing critical illness, and a 1:1 nursing environment – what they cannot do is reverse irreversible pathology. They will want to know that the referrer appreciates this and asks for discrete, measurable modalities of care for their patient.
It is important to set out the goals for that patient’s ICU stay, and also the limits of care. Some examples of this;

A 68 year-old lady being admitted for monitoring and a limited amount of vasopressors (e.g. 48 hours) to help her through the initial period of sepsis while her antibiotics take time to work. She is moderately frail with a few well-managed comorbidities, and states that she would not want to live if she was not able to do her gardening or hold her grandchildren. The consultant decides, based on these discussions with the patient, discussions with other consultants and her assessment, that she does not feel the patient would benefit from renal replacement therapy or intubation. Because she would not be for intubation, they discuss resuscitation status because, naturally, care during- and post-arrest would involve airway support. The patient and team agree to instate a u-DNACPR.

A 25-year-old male is admitted after a traumatic brain injury. He had a good baseline prior to this, with an active manual job and several children. The goals of his ITU admission are to keep him sedated to a RASS -5 (to minimise cerebral metabolism while his brain recovers from its traumatic injury)- this requires deep sedation and, therefore, intubation and ventilation as his GCS is artificially kept too low to do this himself. The ICU team are aware that this patient may require continuous cardiac monitoring and may deteriorate to the point of arrest. They agree this patient should be for full resuscitation and any other organ support he may require.

As a referrer to ITU, it is important to consider what you want to be done for the patient on ICU and communicate this to the senior when you make this call- what organ system requires support?

AirwayDoes their airway need supported because of obstruction, low GCS, trauma impacting airway structures?
BreathingIs there evidence of respiratory failure?If so, what is the most likely cause and the most appropriate means of respiratory support?
CirculationIs there evidence of shock – think hypoperfusion; confusion, chest pain, rising lactate, low BP.What is the most likely cause of this? Is it reversible? What cardiovascular support does the patient require?
DisabilityAfter a primary neurological insult, what protective strategies need to be offered to reduce the risk of secondary cerebral injury?
RenalFor the main indications for emergency renal replacement therapy, think AEIOU-A- Acidosis
E- Electrolytes, primarily hyperkalaemia refractory to medical management I- Ingestion of overdose
O- Overload, which does not respond to diuresis; especially if this is compromising ventilation (e.g. increased oxygen requirements)
U- Urea (symptomatic)Urine output is also an important parameter to discuss with the ICU senior – any patient with an illness severe enough to warrant discussing with ICU should have been catheterised to facilitate close urine output monitoring.
MonitoringDoes the patient require 1:1 nursing, or an enhanced level of observation or monitoring which cannot be delivered anywhere else in the hospital?
What Interventions You Have Already Tried

To accept a referral to ICU, the ICU reg or consultant holding the phone will need to be satisfied that you have reached the ceiling of what can be provided on the wards and that the patient remains unstable or likely to deteriorate.

For example, your septic, hypovolaemic patient in A&E is unlikely to be accepted for pressors if you have only given one bolus of fluid!

If they have any guidance as to further treatments you could try on the ward with fewer risks than an ICU admission, they will also suggest this.

Take your time, and list in chronological order what interventions you have tried, and any evidence of response, for example;

  • MAP (as this is a better indicator of perfusion than systolic BP) before and after fluid resuscitation (NICE suggests 2000ml of IV fluids as the cutoff for involving senior support, the Society of Critical Care Medicine suggest 30ml/kg over 3 hours for patients with septic shock)
  • ABG parameters of gas exchange before and after applying oxygen, and/or NIV if this is something offered to ward patients in your hospital
  • Serum potassium before and after medical management of hyperkalaemia in a patient you are referring for renal replacement therapy.


Referring patients to the intensive care unit can be viewed as a daunting task for a junior doctor- it can be difficult, when faced with a deteriorating patient, to remember to gather all of the information you may be asked for when referring them to ICU. This information-gathering helps the intensive care team help you, and hopefully this article is a useful insight into their rationale!

References and further reading

  • Smith G, Nielsen M. ABC of intensive care. Criteria for admission. BMJ. 1999 Jun 5;318(7197):1544-7. doi: 10.1136/bmj.318.7197.1544. PMID: 10356016; PMCID: PMC1115908.
  • University of Aberdeen (2020) Making decisions about who to admit to Intensive Care, University of Aberdeen. Available at: (Accessed: 09 February 2024).
  • Fullerton JN, Perkins GD. Who to admit to intensive care? Clin Med (Lond). 2011 Dec;11(6):601-4. doi: 10.7861/clinmedicine.11-6-601. PMID: 22268319; PMCID: PMC4952346.

Written by Dr Hannah Blades FY3, Dr Eva Kerr FY2
Reviewed by Dr James Dunning ST3
Edited by Dr Alex Hunt

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