Critical Care Outreach and the Medical Emergency Team (MET)

This chapter is directly relevant to Section 2.1.1 of the CICM Second Part General Exam Syllabus (First Edition), which specifically lists “Rapid Response Systems / Critical Care Outreach” as something an intensive care specialist should have a detailed understanding of. Medical emergency teams had become widespread, to the extent that most people can neither clearly remember a time when there was no such service, or are too young to conceive of what an ICU job would look like without such a service.

  • Question 7 from the first paper of 2001 asked about the elements of a MET system and the expected improvements from such a system (implying that improvements were expected)
  • Question 12 from the first paper of 2005, clearly following the publication of the MERIT trial, asked the trainees to critically evaluate the system without pointing them to any specific conclusion they were supposed to reach.

Of all the possible resources, the most important reading for this topic is the "Joint Position Statement" from CICM, followed by the NSQHS Standard 3 - Guide to the Implementation of Rapid Response Systems (it's now Standard 8).  Medical Emergency Teams: A Guide to Implementation and Outcome Measurement by DeVita Hillman and Bellomo (2006) is probably some kind of definitive resource, but it's 296 pages, which means nobody will read it no matter how vigorously it is recommended. On the other hand, Jones et al (2006), which is Chapter 8 from the above book, is a much better recommendation, and not just because it appropriately starts with a quote from Macchiavelli. 

Principles and practice of ICU Outreach

This is the concept of "ICU without walls", which some uncivilized individuals have extrapolated to "ICU without balls" and "ICU without arms or legs", implying that the extension of critical care services will steal staff from the ICU and make us everybody's bitch, expected to clean up the mess of wealthy interventional specialties who neglect their ward work. These rude people clearly do not represent the opinions of the examiners, who seem to largely be in favour of the MET system (judging by their model answers). The Oh's chapter on this topic certainly seems pro-outreach in its tone, while trying to remain neutral.

Definition of a Rapid Response System (RRS)

  • "A hospital wide structure providing a safety net for patients potentially becoming critically ill who have a mismatch between their clinical needs and the local resources to manage them". - 2016 joint position statement.

The purpose of these outreach teams

  • Prevent ICU admissions
  • Observation and review of patients discharged form the ICU
  • Conserve critical care resources by optimising ward-level patient management
  • Administer ICU-level intervention to patients before they require ICU
  • Education of ward staff in critical care skills

Members of these teams

  • Critical care nurses
  • Nurse practitioners
  • ICU medical staff
  • MET team members
  • Nursing Team Leader
  • Wardsperson
  • Administrative (bed management) staff to facilitate transfer
  • The medical staff consist of:
    • Medical team leader
    • Medical staff skilled in airway management (eg. anaesthetics staff or ICU staff)
    • Medical staff skilled in vascular access (eg. anaesthetics staff or ICU staff)
    • Junior medical officer

Skills deployed by outreach team members

  • ALS
  • Management and care of central lines
  • Management of TPN
  • Management of the patient with a tracheostomy and/or home ventilator


  • Prevention of unnecessary ICU admissions
  • Early management of deteriorating patients
  • Improved level of care received by deteriorating patients
  • Bedside education of ward staff in the management of critically ill patients
  • Expansion of the role and importance of the ICU within the hospital
  • Development of a supportive collaborative relationship with ward staff and hospital medical/surgical teams


  • De-skilling of ward staff in management of critically ill patients
  • Diversion of ICU resources into outreach teams
  • Increased dependence on ICU support in the routine management of ward patients
  • Increased dependence on ICU support in end-of-life decisionmaking

Evidence in support of critical care outreach teams

Evidence against critical care outreach teams

  • There is a difficulty in performing a meta-analysis of the data because of heterogeneity in the implementation of critical care outreach services.
  • At present, there is no strong evidence that critical care outreach services improve any outcomes whatsoever, including cardiac arrest, readmission, unplanned ICU admission, etc.
  • Studies have not been consistent in demonstrating a mortality improvement. Negative findings (i.e. unchanged mortality) have been more consistent.
  • Lack of evidence would normally result in the disinvestment of resources in an ineffective practice, but critical care outreach services -once entrenched - are difficult to uproot.

MET (Medical Emergency Team) services


  • Deterioration of patient is usually heralded by steretypic changes in physiological parameters
  • If this deterioration is detected and averted, the patient is less likely to require ICU admission
  • MET systems aim to increase the rate of early detection, and focus critical care services to the aid of deteriorating patients
  • MET service are coordinated by a system of call criteria based on physiological parameters which - with even minor deviations from normal values - can be sensitive in detecting a patient at risk of ICU admission or death.


  • Call criteria are simple parameters to measure, already routinely collected
  • Potentially, lifesaving treatments can be administered at the appropriate moment
  • Early intervention to prevent cardiac arrest is likely to improve hospital mortality
  • MET services deploy an ICU-level skill set in the ward, which should improve the quality of care for critically ill patients
  • Prevention of ICU admission should be a cost-effective measure, working on the premise that ICU admission is more costly than MET team maintenance.
  • End-of-life care quality should improve with the involvement of ICU staff


  • Diverts ICU resources out of ICU
  • Creates a dependence on ICU for the managemet of deteriorating patients
  • Creates a dependence on ICU staff for end-of-life decisionmaking
  • Decreases the critical care skills of ward staff
  • Expensive in terms of MET maintenance, ward staff education programs, audit activities and ICU resource diversion

Evidence in support of the MET system

Evidence against the use of the MET system

  • No effect on hospital mortality or incidence of cardiac arrest, at the cost of increased resource use (greatly increased MET callouts) according to the MERIT trial from 2005, as well as another more recent (2012) trial by Howell et al.
  • Poor study methodology had resulted in the exclusion of all but two studies from a 2007 Cochrane review. The two remaining studies disagreed as to whether there was any mortality improvement. The Cochrane authors were forced to conclude that no recommendations can be made on the basis of such poor quality evidence.
  • Thus far, no strong evidence exists to support the use of MET teams as a means of decreasing in-hospital mortality.

Relevant evidence for rapid response team design

  • Wilson et al - 1995 - retrospective review of inpatient notes (Australia); n=1400. Rate of adverse events = 16.6%, of which 51% were preventable. 
  • Hillman et al - 2001 - retrospective review of antecedents to inpatient deaths (3 Australian hospitals). n=778; hypotension (30%) and
    tachypnoea (17%) were the most common antecedent.
  • ACADEMIA study - 2004 - prospective observational study of deteriorating inpatients (Australia, NZ, UK). n=638. Predictable antecedents (eg. drop in GCS, hypotension) were seen in 60%. 
  • MERIT trial - 2005 - RRTs in 23 Australian hospitals; n=23 hospitals. No difference in mortality or unplanned ICU admission.
  • Zhang et al - 2024 - systematic review; n=52 papers. Most studies have found no impact; 48% reported decreased mortality and 57% reported a decrease in the rate of cardiac arrest.

Controversies and risks in rapid response system design

The whole concept remains controversial for some, whereas others (having grown up with it) view it as an inevitable part of life. Some debated questions include:

Risks of rapid response service implementation are well described in an excellent paper by Subramaniam et al (2016). In short summary:

  • Doctor-patient relationship is disrupted ("who are these randoms who just turned up and are now telling me my father is dying?")
  • The MET is a huge intrusion into patient privacy, as information is handed over several times in some abbreviated and potentially insensitive form, out aloud and often with many bystanders listening
  • Failed activation of the system by unskilled ward stadff obviously will not prevent any deterioration, failed response to the deterioration by unskilled responders will obviously not reverse any deterioration.
  • Where the ICU services the hospital with MET staff, the ICU loses staff, which interrupts ICU work and potentially puts ICU patients at risk
  • There is inconsistency in the composition and training of MET teams
  • Deskilling of ward staff may occur
  • Exploitation of critical care staff may occur
  • Masking of system failures is a potential byproduct
  • Cost-effectiveness is unknown but could potentially be a net loss, for no specific gain (i.e. if ICU admissions or costly interventions are not prevented, the RRT did not save the system any money).



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McGaughey, Jennifer, et al. "Outreach and Early Warning Systems (EWS) for the prevention of intensive care admission and death of critically ill adult patients on general hospital wards." Cochrane Database Syst Rev 3 (2007).

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Buist, Michael D., et al. "Effects of a medical emergency team on reduction of incidence of and mortality from unexpected cardiac arrests in hospital: preliminary study." Bmj 324.7334 (2002): 387-390.

Bellomo, Rinaldo, et al. "A prospective before-and-after trial of a medical emergency team." Medical Journal of Australia 179.6 (2003): 283-288.

Bright, Debby, Wendy Walker, and Julian Bion. "Clinical review: outreach–a strategy for improving the care of the acutely ill hospitalized patient." Critical Care 8.1 (2003): 1.

Kause, Juliane, et al. "A comparison of antecedents to cardiac arrests, deaths and emergency intensive care admissions in Australia and New Zealand, and the United Kingdom—the ACADEMIA study." Resuscitation 62.3 (2004): 275-282.

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Hillman, K. M., et al. "Antecedents to hospital deaths." Internal medicine journal 31.6 (2001): 343-348.

Zhang, Qiuxia, et al. "Effects of rapid response team on patient outcomes: A systematic review." Heart & Lung 63 (2024): 51-64.

Jones, Daryl, Rinaldo Bellomo, and Donna Goldsmith. "General Principles of Medical Emergency Teams." Medical Emergency Teams: Implementation and Outcome Measurement (2006): 80-90.

Al-Qahtani, Saad, et al. "Impact of an intensivist-led multidisciplinary extended rapid response team on hospital-wide cardiopulmonary arrests and mortality." Critical Care Medicine 41.2 (2013): 506-517.

Mitchell, Anne, Marilyn Schatz, and Heather Francis. "Designing a critical care nurse–led rapid response team using only available resources: 6 years later." Critical Care Nurse 34.3 (2014): 41-56.

Scherr, Kimberly, et al. "Evaluating a new rapid response team: NP-led versus intensivist-led comparisons." AACN advanced critical care 23.1 (2012): 32-42.

Karvellas, Constantine J., et al. "Association between implementation of an intensivist-led medical emergency team and mortality." BMJ Quality & Safety 21.2 (2012): 152-159.

Daniele, Rose Mary, et al. "Rapid response team composition effects on outcomes for adult hospitalised patients: a systematic review." JBI Evidence Synthesis 9.31 (2011): 1297-1340.

Subramaniam, A., J. Botha, and R. Tiruvoipati. "The limitations in implementing and operating a rapid response system." Internal Medicine Journal 46.10 (2016): 1139-1145.