The medical emergency team - current status and future directions: a perspective for acute care physicians.

Abstract

The medical emergency team (MET) describes a team of expert clinicians who are called to review hospitalised patients experiencing clinical deterioration.1, 2 The team is activated when a patient fulfils predefined derangement of vital signs or other acute changes in their clinical condition. The MET concept arose out of observations that patients experiencing cardiac arrest, in-hospital mortality and unplanned admission to the intensive care unit (ICU) displayed objective signs of physiological instability in the period leading up to the event.1, 2 In addition, ward clinicians did not reliably recognise such clinical deterioration or consistently respond in a manner that was commensurate to the degree of illness.3-5 The MET concept is now part of a hospital-wide rapid response system that provides objective criteria to call for assistance along with an expected and timely response by more senior staff.6 Australia was an early adopter of the MET, which commenced around 1995.7 A survey of hospitals with an ICU reported that the responding team is frequently comprised of medical and nursing staff from the ICU.8 Nurse-led teams and teams without ICU staff tend to be seen in smaller metropolitan and rural hospitals.8 In the 25 years since the introduction of the MET, there has been increased patient acuity and an expansion in the treatment provided to hospitalised patients, along with an increased emphasis on outpatient care.9 These changes have increased the need to have reliable systems that detect and treat deteriorating patients. There are now three systematic reviews and meta-analyses reporting that the introduction of METs was associated with reductions in cardiac arrests outside of the ICU in both children and adults.10-12 The relative risk for cardiac arrest following MET introduction was between 0.62 and 0.66 for adults and 0.62 and 0.65 for children. Four studies10-13 reported an associated reduction in hospital mortality with a relative risk of 0.79 to 0.88 for adults and 0.82 for children, and one reported a relative risk of 0.51 for unexpected mortality.11 In contrast, there is much less evidence that the MET can reduce unplanned admissions to the ICU. A limited number of single-centre studies report that the implementation of MET was associated with decreased postoperative adverse events and decreased in-hospital and long-term mortality.14, 15 The optimal composition for the responding team is unknown. Maharaj et al. reported that there was no evidence that inclusion of a physician improved outcomes.12 However, the studies included in this review were heterogeneous, and 25 of 29 (86.2%) studies contained a physician-led MET. One of the major current challenges with the MET model of care is the increasing number of calls. There is a need to develop additional preemptive and reactive strategies to improve further the outcomes of at-risk hospitalised patients16 and to improve the outcome of patients once a MET has occurred. Involvement of physicians and physician trainees (registrars) is pivotal to such strategies, for both medical and surgical patients (Table 1). Before the medical emergency team (MET): During the MET: Attend and participate in their own MET calls. After the MET: Several studies have suggested that patients reviewed by the MET have limitations of treatment or end-of-life care issues in approximately one-third of cases.17, 18 Such end-of-life calls tend to occur out of hours when the treating unit is not present and may be more common in medical than surgical patients.17 End-of-life MET calls may be associated with moral distress in the attending staff that attend, particularly when the patient goals of care are not clear.19, 20 Accordingly, it is incumbent on physicians and registrars to ensure that the goals of care are discussed with patients and clearly documented in the medical record so that treatment provided aligns with patient goals. This is true both before and after the MET call. Physicians and registrars have important roles in the prevention of clinical deterioration and thus may be able to prevent MET calls from occurring. Many hospitals have a pre-MET tier that involves review by the usual treating team for degrees of clinical deterioration that are less extreme than MET criteria.21 One single-centre study suggested that patients who are reviewed by the MET breached the pre-MET triggers for deterioration in 80% of instances.22 Timely review and effective treatment of pre-MET deterioration may avert the need for a subsequent MET call. Physicians and registrars are also frequently involved in the medical comanagement of surgical patients.23 A large proportion of clinical deterioration episodes in surgical patients are not related to the operative site, but rather medical-type problems such as hospital-acquired pneumonia, fluid overload, renal dysfunction and myocardial ischaemia.24 Physicians and trainees have an important role in the prevention, early recognition and timely management of these complications. Registrars are frequently involved in the assessment and management of MET calls. In large teaching hospitals with an ICU, the MET is typically led by an ICU registrar,8 sometimes with consultant input.25 This situation provides an opportunity for education and training for physician trainees, particularly when they are junior or when deterioration is extreme. It is important for physicians and trainees to attend MET calls for their own patients to provide context for the deterioration and to contribute to the ongoing management plan. In circumstances when there is no ICU, or when there is more than one MET occurring simultaneously, registrars may be required to team-lead one of the calls. An additional challenge associated with the MET model is knowing which patients should be admitted to the ICU following the call. Several authors have attempted to develop predictive models to identify which MET patients are at subsequent risk of adverse events, including the need for repeat MET review, requirement for ICU admission or in-hospital mortality.26-28 In the future it is likely that the focus in this area will be to develop strategies that prevent clinical deterioration requiring a MET along with processes to optimise patient outcome once a MET has occurred. There is a need to improve the education and training of staff in the management of clinical deterioration, at both the pre-MET and MET levels. Such training should ideally be interprofessional and commence at the undergraduate level.9 Several courses have been developed to address training of non-ICU staff, including the COMPASS (Early Recognition of the Deteriorating Patient Program)29 and BASIC (Basic Assessment and Support in Intensive Care)30 courses. The Australian and New Zealand Intensive Care Society has developed a course to train ICU registrars in MET management.31 In addition to team-based training to teach nontechnical skills,32 there may be a need to develop guidelines or decision support tools for the management of conditions commonly seen during MET calls, including sepsis33 and pulmonary embolism.34 A further future goal will be increased use of the electronic health care record and MET databases to improve understanding and management of deteriorating patients. Several studies have been conducted to predict which patients are likely to require a MET call to guide the development of strategies that are more proactive in nature.35-38 Currently, MET criteria are relatively sensitive but not specific. Thus, only 20% of patients will be admitted to the ICU following MET review.39 While it is desirable to avoid potentially preventable morbidity and mortality, sensitive activation criteria are likely to contribute to the large number of calls currently being seen. In the future, more complex predictive algorithms might be able to guide in the development of activation mechanisms that are more tailored to the individual patient. As outlined above, several authors have developed predictive algorithms to risk-stratify patients who have received a MET call, to identify which patients are at higher likelihood of subsequent adverse events.26-28 In all instances, predictive algorithms should ideally operate in real-time using information from the electronic health care record in conjunction with changes in patient vital signs. They will also need to be linked with triggers and activation mechanisms to alert clinicians to the development of deterioration. In summary, the MET has evolved into a major method for the recognition of, and response to, clinical deterioration for hospitalised patients. Although implementation of the MET has been associated with improved patient outcomes, there is a need to develop additional strategies to address the clinical deterioration of hospitalised patients. Physicians and registrars will be central in these processes before, during and after the MET has occurred, both in medical as well as surgical patients.