Critical care services in the English NHS

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The national focus on critical care services in England has increased because of Covid-19 (coronavirus). A significant proportion of hospitalised patients with Covid-19 require help with breathing, including mechanical ventilation, and other services critical care staff and units provide. The need to avoid critical care units being overwhelmed as Covid-19 cases rise has been cited as a key factor in significant policy decisions, including regional and national ‘lockdowns’. 

This briefing brings together information on critical care services in England to highlight the important role these services play. It should be noted that to reduce pressures on frontline NHS services, NHS England has paused the collection and publication of official statistics on critical care bed capacity. This means there is no publicly available information on the total number of critical care beds available to the NHS (including beds in existing NHS hospitals, the NHS Nightingale hospitals, and capacity purchased from the independent sector). 

What is critical care?

Critical care units (CCUs) are specialist hospital wards that treat patients who are seriously ill and need constant monitoring. These patients might, for example, have problems with one or more vital organ or be unable to breathe without support.

These units are staffed by specially trained health care professionals who deliver intensive levels of care and treatment, for example, there is usually one nurse for every one or two patients. Patients in these units are closely monitored and supported by sophisticated equipment, including ventilators that help patients breathe.

CCUs can range from 4 beds to more than 50 beds (Table 1), depending on factors such as the type and number of patients the unit expects to see and on the work and size of the hospital it is part of. Larger units are often divided into smaller units (eg, 8–10 beds) to make the delivery of care more manageable.

Table 1 Size of critical care units, April 2018
Number of funded level 2 and 3 critical care bedsPercentage of units
Fewer than 62.9
More than 30 beds10.0

Source: Critical Care Networks National Nurse Leads

Notes: Data for England, Wales and Northern Ireland. Data based on a survey, rather than census, of units. Unit size reported for each workforce survey received so, for example, two 20-bed units supported by staff in the same hospital may appear as one 40-bed unit. Numbers may not sum due to rounding. April 2018 publication of data collected over autumn 2017.

Critical care staff can also provide services outside the physical environment of the CCU. For example, as part of a rapid emergency response team or by offering an outreach service to patients in need of critical care in other parts of the hospital.

Different types and levels of critical care

The NHS has different levels of critical care, based on the clinical needs of patients.

  • Level 0 – patients whose needs can be met through normal ward care in an acute hospital.
  • Level 1 critical care – patients at risk of their condition deteriorating or those recently relocated from higher levels of care, whose needs can be met on an acute ward with additional advice and support from the critical care team.  
  • Level 2 critical care – patients requiring more detailed observation or intervention, including support for a single failing organ system or post-operative care and those ‘stepping down’ from higher levels of care. Also known as ‘high dependency units’ (HDUs).
  • Level 3 critical care – patients requiring advanced respiratory support alone or basic respiratory support together with support of at least two organ systems. This level includes all complex patients requiring support for multi-organ failure. Also known as ‘intensive care units’ (ICUs) or ‘intensive treatment/therapy units’ (ITUs).

CCU is sometimes used as the umbrella term for both level-3 (ICU) and level-2 (HDU) services. The majority (73 per cent) of CCUs are configured to use a mix of level-2 and level-3 beds flexibly, with a minority of units configured specifically for only level-2 beds or only level-3 beds (see Figure 1). Some CCUs specialise in providing care for particular clinical conditions, such as coronary CCUs for patients with severe heart problems.

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CCUs can also be distinguished based on the age of the patient: adult critical care, neonatal intensive care units (NICUs) for newborn babies and paediatric intensive care units (PICUs).

CCUs are organised into 15–20 collaborative geographical networks across England called operational delivery networks. These networks support hospitals providing adult critical care services through sharing knowledge, expertise and practical support across different units. This support is particularly important for the very small number of CCUs that are in geographically remote locations, where the number of patients might be lower and where transferring patients between different units may take longer.

The number of critical care beds

Critical care beds in the NHS

National data on the number and availability of critical care beds is usually collected in three ways.

  • Monthly sitreps – a monthly snapshot of bed numbers, taken on midnight on the last Thursday of each month to provide a routine situation report (sitrep).
  • Winter daily sitreps – taken at midday daily over the winter reporting period (usually from late November to March). This information is only collected for NHS trusts that provide type 1 (major consultant-led) accident and emergency (A&E) services and will not include critical care capacity in some specialist trusts, such as hospitals for the treatment of cancer.
  •  Additional information on bed availability is collected twice daily for operational planning and co-ordination in the NHS, but this data is not routinely published.

Unlike most other categories of hospital bed in the NHS, the total number of critical care beds has increased in recent years. Monthly data for January 2020 indicates there were around 5,900 critical care beds, which is 13 per cent higher than the 5,200 in January 2011 (see Figure 2). Of these, 4,100 (just under 70 per cent) are for use by adults, with the remainder for children and infants.

NHS England has noted the demand for level-2 (high dependency) and level-3 (intensive care) critical care will continue to grow in the long term. A growing and ageing population, and advances in medical technology, will increase the need for critical care services that can support more specialised and complex procedures such as bone marrow transplants, solid organ transplants and arterial thrombectomy (removing blood clots).

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A wide range of NHS hospitals have CCUs, though beds numbers are higher in larger hospitals and specialist hospitals that perform very complex medical and surgical procedures (see Figure 3).

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Critical care and private hospitals

The vast majority of critical care beds are in NHS hospitals. But a small number of private hospitals also have these facilities.

Comprehensive data on private sector critical care beds is not routinely available in the public domain, but, for illustration, a 2011 data collection by the Competition Commission found there were 85 level-3 critical care beds in London operated by HCA International, BMI, BUPA, and The London Clinic (see Table 2). The majority of these were provided by HCA International which operates level-2 and level-3 adult ICUs at all its major hospitals.

Table 2 Critical care capacity in private hospitals providing inpatient services in central London, 2011
ProviderNumber of critical care level-3 beds
The London Clinic11
The BUPA Cromwell7
King Edward VII's Sister Agnes4

Source: Competition Commission


Separate 2018/19 data from NHS Digital records critical care activity at units operated in England by other providers including Spire Healthcare and Ramsay Healthcare. The Cleveland Clinic has also announced plans to open a new hospital in London in 2021, which would have 30 critical care beds capable of providing level-3 support to patients – making this one of the largest private critical care units in the United Kingdom.

In 2020, a LaingBuisson report on the acute health care market in central London indicated there were 102 intensive care beds operated by the private sector.

International comparisons

There is no recent or comprehensive international data on critical care capacity. In 2014, Monitor – the regulator of foundation trusts at the time – reviewed critical care services in a selection of Western health systems.

Data collated for a review of different journal articles showed substantial variation in the number of critical care beds per head of population across a range of advanced health systems (see Figure 4). The authors noted that this may, in part, be due to variation in how CCUs are identified across different countries, and the extent to which neonatal and paediatric intensive care units are captured in the data. With these caveats, in the two most recent studies the UK’s critical care capacity was towards the middle of the countries studied.

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Bed occupancy in critical care units

Occupancy levels in CCUs are generally lower than for other acute hospital beds (see Figure 5). In January 2020, 3,423 (83 per cent) of the 4,123 available adult critical care beds were occupied.

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Activity in critical care units

Admission to CCUs is usually based on the severity of the patient’s illness rather than their specific underlying diagnosis. Patients may be admitted after serious accidents, conditions such as heart attack or stroke, infections such as sepsis or pneumonia, or for planned recovery after major complex surgery. For unscheduled admissions, such as patients arriving to hospital in an emergency, it is expected that admission to the CCU will happen within four hours of the decision to admit the patient.

Data are also collected on which organs require support from critical care teams. Figure 6 shows that support for cardiovascular and respiratory organs accounted for more periods of critical care support than other types of support. However, these patients stay in CCUs for shorter periods than patients who require support for gastrointestinal conditions or dermatological conditions (eg, severe skin burns). Because patients may stay in critical care for only a few hours in some cases, analysis of the average length of stay should be treated with some caution.

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In 2018/19, the vast majority (76 per cent) of patients who leave critical care units are discharged to hospital wards to continue their recovery (see Figure 7). National specifications expect patients to be discharged from critical care units to hospital wards within four hours of the discharge decision being made. But due to a shortage of available hospital ward beds, more than a quarter (27 per cent) of discharges in 2018/19 were delayed (NHS Digital 2019).

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Critical care services rely on highly trained specialised staff who deliver intensive levels of care. A wide variety of staff support or work in CCUs, including medical doctors, nurses and allied health professionals .

Because patients in CCUs need constant monitoring and specialist support, clinical guidelines require a high level of expert staff to be available in these units.


According to national service specifications for adult critical care, it is expected that CCUs should have minimum nursing establishments that allow one registered nurse per patient staffing levels for level-3 (intensive care) patients; and one nurse for every two patients for level-2 (high dependency) patients.

Nurses in CCUs are expected to have specialist skills including, for example, having knowledge of advanced assessments of patients’ breathing and the advantages and disadvantages of non-invasive and invasive therapies to support breathing, such as mechanical ventilation. There is an expectation that training will be provided so that at least half of the nurses in these units have a post-registration award in critical care nursing.

A 2017 survey of nurses working in critical care services found an 8 per cent vacancy rate in the critical care nursing workforce, with higher vacancy rates in North Central and East London, the South East Coast and the South West. An increasing number of units were seeking to recruit registered nurses from overseas to fill vacancies. Nationally, 9.9 per cent of the critical care nursing workforce was made up of staff from EU countries with a further 16.6 per cent recruited from outside the European Union.


Intensive care is a consultant-led service, with a consultant in intensive care medicine immediately available to attend patients, and substantial consultant-level input into key decisions on the admission, care and discharge of patients.

Guidance from the Faculty of Intensive Care Medicine and the Intensive Care Society specifies that in daytime consultants should not normally be responsible for more than 8 to 12 patients. The night-time ratio is not defined. The guidelines note these ratios must have regard to circumstances including the number and complexity of patients and the seniority and competency of non-consultant staff.

Data from NHS Digital shows the number of intensive care doctors in England has risen in recent years (see Figure 8). Though, of course, doctors from other medical specialities – particularly anaesthesia – and other staff groups play a crucial role in delivering critical care.

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Allied health professionals

Some patients in critical care units will experience extended periods of time when they are immobile and given support to breathe. Allied health professionals play essential roles in ensuring these patients receive the care they need during treatment and recovery. For example:

  • physiotherapists help maintain or strengthen the muscles of patients who spend long periods in bed 
  • occupational therapists assess and support the ability of critical care patients to carry out activities of daily living such as bathing and feeding, and help meet the emotional and psychological needs of patients who have gone through periods of critical illness
  • pharmacists provide expert advice on medicines for treatment and recovery
  • dieticians support patients’ nutritional needs, including through advice on how to feed patients through feeding tubes and drips
  • speech and language therapists can assist patients recover their ability to speak after being on breathing tubes or receiving tracheostomies (which involves a hole being made in a patient’s throat to help them breathe). 

Covid-19 (coronavirus)

In early 2020, the Covid-19 pandemic rapidly increased the demand for NHS services, particularly services like critical care that treat patients with severe acute respiratory disease.

Increasing the NHS’s capacity to deliver critical care 

In response to the growing pressures from Covid-19, the NHS was asked to free up the maximum possible inpatient and critical care capacity and prepare for a large number of hospital patients requiring advanced support to help them breathe. This response included several areas of action.

Critical care activity during Covid-19

To reduce the burden on frontline services, NHS England and NHS Improvement paused the collection and publication of official statistics on critical care units – although a wide range of data on NHS capacity is being routinely collected to inform the national response to the pandemic.

There is still some publicly available information on critical care activity. Data from the national coronavirus dashboard – which include information from the Nightingale hospitals – shows the increase in the number of patients on ventilation during the first and second waves of Covid-19 (Figure 9). 

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Additional data from Intensive Care National Audit and Research Centre (ICNARC), which covers England, Wales and Northern Ireland, provides a more detailed picture of the critical care patients with Covid-19 receive.

Comprehensive data is not yet available on the experience of NHS critical care staff during the pandemic. A global survey of the impact of Covid-19 on critical care staff from more than 70 countries found emotional distress or burnout was high across critical care providers, and associated with a range of factors that included shortages of intensive care nurses and difficulties in accessing appropriate equipment. In November 2020, a survey of intensive care consultants across the NHS in all four countries of the UK found that while 45 per cent of consultants said their critical care units had permanently expanded capacity after the first wave of Covid-19, only 18 per cent said these extra beds were adequately staffed. These staffing pressures meant the majority of doctors responding to the survey had worked longer hours and cancelled leave to help their units cope. 


Critical care units have been at the front line in the response to Covid-19 and the NHS has taken unprecedented action to increase critical care capacity to cope with the Covid-19 pandemic. Despite this, the risk of critical care services being overwhelmed remains and has been cited as a major factor behind repeated regional and national lockdowns in England.

Delivering sufficient critical care capacity goes beyond physical infrastructure – such as having more beds and equipment – and requires sufficient numbers of trained and available staff. The recently reported changes to clinical staffing ratios reflects, in part, that there are simply not enough staff to make use of the additional physical resources the NHS is investing in. And while data is still emerging, it is increasingly clear that the pandemic is taking a substantial toll on the staff who support and deliver critical care services.

The ultimate outcome for patients and staff will not only depend on how effective measures to increase critical care capacity are, but also on the wider measures that are taken to contain the spread of the virus and avoid a surge in demand that would overwhelm even the most well-prepared services. A second wave of Covid-19 and looming winter pressures mean that NHS staff and services will continue to be tested to their limits over the coming months.


Hans Lindor

Comment date
24 May 2022

Thanks for sharing this article. Because of our busyness in our corporate life, we are unable to give time to our seniors. So, in that case, they feel lonely, boring even don't get their medical needs properly. That's why it's better to get home care services for our seniors.

Siva Anandaciva

Chief Analyst,
The King's Fund
Comment date
24 July 2020

Hi Karen,

The data on critical care bed capacity at least will be published here eventually, but data reporting has been paused for Covid-19.…

But it might be worth asking if they can give you the denominators that are used to produce these data on beds and patients requiring ventilation…

Karen Patterson

Senior Lecturer at the Univ. of Sussex / Respirologist and Critical Care doctor,
Comment date
23 July 2020

Hello - I'd be grateful for any links or resources which substantiate the report (in newspapers) that the number of critical care and/or ventilators per capita are - in England - higher in London compared to the rest of the country. Many thanks in advance.

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