Question 12

College Answer

Medical Emergency Teams in various formats have been used to manage in-hospital emergencies for over a decade.  Despite this, only limited data is available for an evidence- based review.   One very large prospective randomised (by hospital) study (MERIT) has been performed but its results have not been published.  Various lower levels of evidence are available (eg. before and after intervention studies Goldhill 1999, Buist 2002, Bellomo

2003) and some of these have shown improvements in a number of outcomes (including cardiac arrest rates and improved survival, and length of ICU stay following cardiac arrest). Other studies have also demonstrated trends to improvement in overall mortality and unplanned ICU admissions (Bristow 2000, Kenward 2004).  Potential problems associated with implementation include cost (staff, equipment), diversion of staff from other roles, and obvious requirement for appropriate educational strategies.

Discussion

The MET concept - even in 2005 - was not exactly fresh and new.

However, this question came at a time during which MET research consisted largely of small-scale single centre experiences, which were uniformly positive -largely because they were implemented by enthusiastic and highly motivated personnel. Thus, one can conclude that the early bedside intervention by enthusiastic and highly motivated critical care personnel improves in-hospital survival and prevents cardiac arrest. Subsequent meta-analysis literature was not so favourable. If one applies strict exclusion criteria to the available bank of studies, one is forced to exclude the vast majority on the grounds of poor methodology (just as the Cochrane reviewers did). The remaining high quality data is poxy wih heterogeneity and offers an unsteady foundation upon which to build conclusions.

The answer to this question, compiled from the LITFL review of this topic as well as the relevant evidence from the literature, would ideally look like this:

Rationale

• Deterioration of patient is ususally 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.

Advantages

• 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

Disadvantages

• 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

• Early detection of deteriorating patients can prevent the need for advanced life support.
• Early studies had demonstrated an improvement in mortality from unexpected cardiac arrest, once MET services became available

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 asanother 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.

Goldhill, D. R., et al. "The patient-at-risk team: identifying and managing seriously ill ward patients." ANAESTHESIA-LONDON- 54 (1999): 853-860.

Hillman, Ken, et al. "Introduction of the medical emergency team (MET) system: a cluster-randomised controlled trial." Lancet 365.9477 (2005): 2091-2097.

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).

Howell, Michael D., et al. "Sustained effectiveness of a primary-team–based rapid response system." Critical care medicine 40.9 (2012): 2562.

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.