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European Resuscitation Council Guidelines for Resuscitation 2015

Section 3. Adult advanced life support

      Introduction

      Adult advanced life support (ALS) includes advanced interventions after basic life support has started and when appropriate an automated external defibrillator (AED) has been used. Adult basic life support (BLS) and use of AEDs is addressed in Section 2. The transition between basic and advanced life support should be seamless as BLS will continue during and overlap with ALS interventions. This section on ALS includes the prevention of cardiac arrest, specific aspects of prehospital ALS, starting in-hospital resuscitation, the ALS algorithm, manual defibrillation, airway management during CPR, drugs and their delivery during CPR, and the treatment of peri-arrest arrhythmias. There are two changes in the presentation of these guidelines since European Resuscitation Council (ERC) Guidelines 2010.
      • Deakin C.D.
      • Nolan J.P.
      • Soar J.
      • et al.
      European Resuscitation Council Guidelines for Resuscitation 2010 Section 4. Adult advanced life support.
      There is no longer a separate section on electrical therapies
      • Deakin C.D.
      • Nolan J.P.
      • Sunde K.
      • Koster R.W.
      European Resuscitation Council Guidelines for Resuscitation 2010 Section 3. Electrical therapies: automated external defibrillators, defibrillation, cardioversion and pacing.
      and the ALS aspects are now part of this section. Post-resuscitation care guidelines are presented in a new section (Section 5) that recognises the importance of the final link in the Chain of Survival.
      • Nolan J.
      • Soar J.
      • Eikeland H.
      The chain of survival.
      These Guidelines are based on the International Liaison Committee on Resuscitation (ILCOR) 2015 Consensus on Science and Treatment Recommendations (CoSTR) for ALS.
      • Soar J.
      • Callaway C.W.
      • Aibiki M.
      • et al.
      Part 4: Advanced life support: 2015 International consensus on cardiopulmonary resuscitation and emergency cardiovascular care science with treatment recommendations.
      The 2015 ILCOR review focused on 42 topics organised in the approximate sequence of ALS interventions: defibrillation, airway, oxygenation and ventilation, circulatory support, monitoring during CPR, and drugs during CPR. For these Guidelines the ILCOR recommendations were supplemented by focused literature reviews undertaken by the ERC ALS Writing Group for those topics not reviewed in the 2015 ILCOR CoSTR. Guidelines were drafted and agreed by the ALS Writing Group members before final approval by the ERC General Assembly and ERC Board.

      Summary of changes since 2010 Guidelines

      The 2015 ERC ALS Guidelines have a change in emphasis aimed at improved care and implementation of these guidelines in order to improve patient focused outcomes.
      • Soreide E.
      • Morrison L.
      • Hillman K.
      • et al.
      The formula for survival in resuscitation.
      The 2015 ERC ALS Guidelines do not include any major changes in core ALS interventions since the previous ERC guidelines published in 2010.
      • Deakin C.D.
      • Nolan J.P.
      • Soar J.
      • et al.
      European Resuscitation Council Guidelines for Resuscitation 2010 Section 4. Adult advanced life support.
      • Deakin C.D.
      • Nolan J.P.
      • Sunde K.
      • Koster R.W.
      European Resuscitation Council Guidelines for Resuscitation 2010 Section 3. Electrical therapies: automated external defibrillators, defibrillation, cardioversion and pacing.
      The key changes since 2010 are:
      • Continuing emphasis on the use of rapid response systems for care of the deteriorating patient and prevention of in-hospital cardiac arrest.
      • Continued emphasis on minimally interrupted high-quality chest compressions throughout any ALS intervention: chest compressions are paused briefly only to enable specific interventions. This includes minimising interruptions in chest compressions to attempt defibrillation.
      • Keeping the focus on the use of self-adhesive pads for defibrillation and a defibrillation strategy to minimise the preshock pause, although we recognise that defibrillator paddles are used in some settings.
      • There is a new section on monitoring during ALS with an increased emphasis on the use of waveform capnography to confirm and continually monitor tracheal tube placement, quality of CPR and to provide an early indication of return of spontaneous circulation (ROSC).
      • There are a variety of approaches to airway management during CPR and a stepwise approach based on patient factors and the skills of the rescuer is recommended.
      • The recommendations for drug therapy during CPR have not changed, but there is greater equipoise concerning the role of drugs in improving outcomes from cardiac arrest.
      • The routine use of mechanical chest compression devices is not recommended, but they are a reasonable alternative in situations where sustained high-quality manual chest compressions are impractical or compromise provider safety.
      • Peri-arrest ultrasound may have a role in identifying reversible causes of cardiac arrest.
      • Extracorporeal life support techniques may have a role as a rescue therapy in selected patients where standard ALS measures are not successful.

      3a – Prevention of in-hospital cardiac arrest

      Early recognition of the deteriorating patient and prevention of cardiac arrest is the first link in the chain of survival.
      • Nolan J.
      • Soar J.
      • Eikeland H.
      The chain of survival.
      Once cardiac arrest occurs, only about 20% of patients who have an in-hospital cardiac arrest will survive to go home.
      • Sandroni C.
      • Nolan J.
      • Cavallaro F.
      • Antonelli M.
      In-hospital cardiac arrest: incidence, prognosis and possible measures to improve survival.
      • Nolan J.P.
      • Soar J.
      • Smith G.B.
      • et al.
      Incidence and outcome of in-hospital cardiac arrest in the United Kingdom National Cardiac Arrest Audit.
      The key recommendations for the prevention of in-hospital cardiac arrest are unchanged since the previous guidance in 2010.
      • Deakin C.D.
      • Nolan J.P.
      • Soar J.
      • et al.
      European Resuscitation Council Guidelines for Resuscitation 2010 Section 4. Adult advanced life support.
      We suggest an approach to prevention of in-hospital cardiac arrest that includes staff education, monitoring of patients, recognition of patient deterioration, a system to call for help and an effective response – the chain of prevention.
      • Smith G.B.
      In-hospital cardiac arrest: is it time for an in-hospital ‘chain of prevention’?.

      The problem

      Cardiac arrest in patients in unmonitored ward areas is not usually a sudden unpredictable event.
      National Confidential Enquiry into Patient Outcome and Death. An acute problem?.
      Patients often have slow and progressive physiological deterioration, involving hypoxaemia and hypotension that is unnoticed or poorly managed by ward staff.
      • Hodgetts T.J.
      • Kenward G.
      • Vlackonikolis I.
      • et al.
      Incidence, location and reasons for avoidable in-hospital cardiac arrest in a district general hospital.
      • Kause J.
      • Smith G.
      • Prytherch D.
      • Parr M.
      • Flabouris A.
      • Hillman K.
      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.
      • Castagna J.
      • Weil M.H.
      • Shubin H.
      Factors determining survival in patients with cardiac arrest.
      The initial cardiac arrest rhythm is usually non-shockable
      • Sandroni C.
      • Nolan J.
      • Cavallaro F.
      • Antonelli M.
      In-hospital cardiac arrest: incidence, prognosis and possible measures to improve survival.
      • Nolan J.P.
      • Soar J.
      • Smith G.B.
      • et al.
      Incidence and outcome of in-hospital cardiac arrest in the United Kingdom National Cardiac Arrest Audit.
      and survival to hospital discharge is poor, particularly in patients with preceding signs of respiratory depression or shock.
      • Nolan J.P.
      • Soar J.
      • Smith G.B.
      • et al.
      Incidence and outcome of in-hospital cardiac arrest in the United Kingdom National Cardiac Arrest Audit.
      • Skrifvars M.B.
      • Nurmi J.
      • Ikola K.
      • Saarinen K.
      • Castren M.
      Reduced survival following resuscitation in patients with documented clinically abnormal observations prior to in-hospital cardiac arrest.
      Early and effective treatment might prevent some cardiac arrests, deaths and unanticipated ICU admissions. Studies conducted in hospitals with traditional cardiac arrest teams have shown that patients attended by the team but who were found not to have a cardiac arrest, have a high morbidity and mortality.
      • Cashman J.N.
      In-hospital cardiac arrest: what happens to the false arrests?.
      • Hein A.
      • Thoren A.B.
      • Herlitz J.
      Characteristics and outcome of false cardiac arrests in hospital.
      • Kenward G.
      • Robinson A.
      • Bradburn S.
      • Steeds R.
      False cardiac arrests: the right time to turn away?.
      Registry data from the US suggests that hospitals with lowest incidence of IHCA also have the highest CA survival.
      • Chen L.M.
      • Nallamothu B.K.
      • Spertus J.A.
      • Li Y.
      • Chan P.S.
      Association between a hospital's rate of cardiac arrest incidence and cardiac arrest survival.

      Nature of the deficiencies in the recognition and response to patient deterioration

      These include infrequent, late or incomplete vital signs assessments; lack of knowledge of normal vital signs values; poor design of vital signs charts; poor sensitivity and specificity of ‘track and trigger’ systems; failure of staff to increase monitoring or escalate care, and staff workload.
      • Fuhrmann L.
      • Lippert A.
      • Perner A.
      • Ostergaard D.
      Incidence, staff awareness and mortality of patients at risk on general wards.
      • Chatterjee M.T.
      • Moon J.C.
      • Murphy R.
      • McCrea D.
      The “OBS” chart: an evidence based approach to re-design of the patient observation chart in a district general hospital setting.
      • Smith G.B.
      • Prytherch D.R.
      • Schmidt P.E.
      • Featherstone P.I.
      Review and performance evaluation of aggregate weighted ‘track and trigger’ systems.
      • Smith G.B.
      • Prytherch D.R.
      • Schmidt P.E.
      • Featherstone P.I.
      • Higgins B.
      A review, and performance evaluation, of single-parameter “track and trigger” systems.
      • Hillman K.
      • Chen J.
      • Cretikos M.
      • et al.
      Introduction of the medical emergency team (MET) system: a cluster-randomised controlled trial.
      • Needleman J.
      • Buerhaus P.
      • Mattke S.
      • Stewart M.
      • Zelevinsky K.
      Nurse-staffing levels and the quality of care in hospitals.
      • DeVita M.A.
      • Smith G.B.
      • Adam S.K.
      • et al.
      “Identifying the hospitalised patient in crisis” – a consensus conference on the afferent limb of rapid response systems.
      • Hogan J.
      Why don’t nurses monitor the respiratory rates of patients?.
      • Buist M.
      The rapid response team paradox: why doesn’t anyone call for help?.
      Problems with assessing and treating airway, breathing and circulation abnormalities as well organisational problems such as poor communication, lack of teamwork and insufficient use of treatment limitation plans are not infrequent.
      • Hodgetts T.J.
      • Kenward G.
      • Vlackonikolis I.
      • et al.
      Incidence, location and reasons for avoidable in-hospital cardiac arrest in a district general hospital.
      • McQuillan P.
      • Pilkington S.
      • Allan A.
      • et al.
      Confidential inquiry into quality of care before admission to intensive care.
      • Andrews T.
      • Waterman H.
      Packaging: a grounded theory of how to report physiological deterioration effectively.

      Education in acute care

      Several studies show that medical and nursing staff lack knowledge and skills in acute care,
      • Derham C.
      Achieving comprehensive critical care.
      • Smith G.B.
      • Poplett N.
      Knowledge of aspects of acute care in trainee doctors.
      • Meek T.
      New house officers’ knowledge of resuscitation, fluid balance and analgesia.
      • Gould T.H.
      • Upton P.M.
      • Collins P.
      A survey of the intended management of acute postoperative pain by newly qualified doctors in the south west region of England in August 1992.
      • Jackson E.
      • Warner J.
      How much do doctors know about consent and capacity?.
      • Kruger P.S.
      • Longden P.J.
      A study of a hospital staff's knowledge of pulse oximetry.
      • Howell M.
      Pulse oximetry: an audit of nursing and medical staff understanding.
      • Wheeler D.W.
      • Remoundos D.D.
      • Whittlestone K.D.
      • et al.
      Doctors’ confusion over ratios and percentages in drug solutions: the case for standard labelling.
      • Campello G.
      • Granja C.
      • Carvalho F.
      • Dias C.
      • Azevedo L.F.
      • Costa-Pereira A.
      Immediate and long-term impact of medical emergency teams on cardiac arrest prevalence and mortality: a plea for periodic basic life-support training programs.
      e.g. oxygen therapy,
      • Smith G.B.
      • Poplett N.
      Knowledge of aspects of acute care in trainee doctors.
      fluid and electrolyte balance,
      • Meek T.
      New house officers’ knowledge of resuscitation, fluid balance and analgesia.
      analgesia,
      • Gould T.H.
      • Upton P.M.
      • Collins P.
      A survey of the intended management of acute postoperative pain by newly qualified doctors in the south west region of England in August 1992.
      issues of consent,
      • Jackson E.
      • Warner J.
      How much do doctors know about consent and capacity?.
      pulse oximetry,
      • Smith G.B.
      • Poplett N.
      Knowledge of aspects of acute care in trainee doctors.
      • Kruger P.S.
      • Longden P.J.
      A study of a hospital staff's knowledge of pulse oximetry.
      • Howell M.
      Pulse oximetry: an audit of nursing and medical staff understanding.
      and drug doses.
      • Wheeler D.W.
      • Remoundos D.D.
      • Whittlestone K.D.
      • et al.
      Doctors’ confusion over ratios and percentages in drug solutions: the case for standard labelling.
      Staff education is an essential part of implementing a system to prevent cardiac arrest but to date, randomised controlled studies addressing the impact of specific educational interventions are lacking.
      • Campello G.
      • Granja C.
      • Carvalho F.
      • Dias C.
      • Azevedo L.F.
      • Costa-Pereira A.
      Immediate and long-term impact of medical emergency teams on cardiac arrest prevalence and mortality: a plea for periodic basic life-support training programs.
      In one study, virtually all the improvement in the hospital cardiac arrest rate occurred during the educational phase of implementation of a medical emergency team (MET) system.
      • Bellomo R.
      • Goldsmith D.
      • Uchino S.
      • et al.
      A prospective before-and-after trial of a medical emergency team.
      • Bellomo R.
      • Goldsmith D.
      • Uchino S.
      • et al.
      Prospective controlled trial of effect of medical emergency team on postoperative morbidity and mortality rates.
      Rapid response teams, such as METs, play a role in educating and improving acute care skills of ward personnel.
      • Campello G.
      • Granja C.
      • Carvalho F.
      • Dias C.
      • Azevedo L.F.
      • Costa-Pereira A.
      Immediate and long-term impact of medical emergency teams on cardiac arrest prevalence and mortality: a plea for periodic basic life-support training programs.
      • Butcher B.W.
      • Quist C.E.
      • Harrison J.D.
      • Ranji S.R.
      The effect of a rapid response team on resident perceptions of education and autonomy.
      The introduction of specific, objective calling criteria,
      • DeVita M.A.
      • Braithwaite R.S.
      • Mahidhara R.
      • Stuart S.
      • Foraida M.
      • Simmons R.L.
      Use of medical emergency team responses to reduce hospital cardiopulmonary arrests.
      referral tools
      • Green A.L.
      • Williams A.
      An evaluation of an early warning clinical marker referral tool.
      and feedback to caregivers
      • Foraida M.I.
      • DeVita M.A.
      • Braithwaite R.S.
      • Stuart S.A.
      • Brooks M.M.
      • Simmons R.L.
      Improving the utilization of medical crisis teams (Condition C) at an urban tertiary care hospital.
      has resulted in improved MET use and a significant reduction in cardiac arrests. Another study found that the number of cardiac arrest calls decreased while pre-arrest calls increased after implementing a standardised educational programme
      • Soar J.
      • Perkins G.D.
      • Harris S.
      • et al.
      The immediate life support course.
      in two hospitals
      • Spearpoint K.G.
      • Gruber P.C.
      • Brett S.J.
      Impact of the Immediate Life Support course on the incidence and outcome of in-hospital cardiac arrest calls: an observational study over 6 years.
      ; this was associated with a decrease in CA incidence and improved CA survival. Other research suggests that multi-professional education did not alter the rate of mortality or staff awareness of patients at risk on general wards.
      • Fuhrmann L.
      • Perner A.
      • Klausen T.W.
      • Ostergaard D.
      • Lippert A.
      The effect of multi-professional education on the recognition and outcome of patients at risk on general wards.

      Monitoring and recognition of the critically ill patient

      Clinical signs of acute illness are similar whatever the underlying process, as they reflect failing respiratory, cardiovascular and neurological systems. Alterations in physiological variables, singly or in combination are associated with, or can be used to predict the occurrence of cardiac arrest,
      • Castagna J.
      • Weil M.H.
      • Shubin H.
      Factors determining survival in patients with cardiac arrest.
      • Jacques T.
      • Harrison G.A.
      • McLaws M.L.
      • Kilborn G.
      Signs of critical conditions and emergency responses (SOCCER): a model for predicting adverse events in the inpatient setting.
      • Cretikos M.
      • Chen J.
      • Hillman K.
      • Bellomo R.
      • Finfer S.
      • Flabouris A.
      The objective medical emergency team activation criteria: a case-control study.
      • Hodgetts T.J.
      • Kenward G.
      • Vlachonikolis I.G.
      • Payne S.
      • Castle N.
      The identification of risk factors for cardiac arrest and formulation of activation criteria to alert a medical emergency team.
      • Fieselmann J.
      • Hendryx M.
      • Helms C.
      • Wakefield D.
      Respiratory rate predicts cardiopulmonary arrest for internal medicine patients.
      hospital death
      • Smith G.B.
      • Prytherch D.R.
      • Schmidt P.E.
      • Featherstone P.I.
      Review and performance evaluation of aggregate weighted ‘track and trigger’ systems.
      • Smith G.B.
      • Prytherch D.R.
      • Schmidt P.E.
      • Featherstone P.I.
      • Higgins B.
      A review, and performance evaluation, of single-parameter “track and trigger” systems.
      • Henry O.F.
      • Blacher J.
      • Verdavaine J.
      • Duviquet M.
      • Safar M.E.
      Alpha 1-acid glycoprotein is an independent predictor of in-hospital death in the elderly.
      • Barlow G.
      • Nathwani D.
      • Davey P.
      The CURB65 pneumonia severity score outperforms generic sepsis and early warning scores in predicting mortality in community-acquired pneumonia.
      • Sleiman I.
      • Morandi A.
      • Sabatini T.
      • et al.
      Hyperglycemia as a predictor of in-hospital mortality in elderly patients without diabetes mellitus admitted to a sub-intensive care unit.
      • Alarcon T.
      • Barcena A.
      • Gonzalez-Montalvo J.I.
      • Penalosa C.
      • Salgado A.
      Factors predictive of outcome on admission to an acute geriatric ward.
      • Goel A.
      • Pinckney R.G.
      • Littenberg B.
      APACHE II predicts long-term survival in COPD patients admitted to a general medical ward.
      • Rowat A.M.
      • Dennis M.S.
      • Wardlaw J.M.
      Central periodic breathing observed on hospital admission is associated with an adverse prognosis in conscious acute stroke patients.
      • Neary W.D.
      • Prytherch D.
      • Foy C.
      • Heather B.P.
      • Earnshaw J.J.
      Comparison of different methods of risk stratification in urgent and emergency surgery.
      • Asadollahi K.
      • Hastings I.M.
      • Beeching N.J.
      • Gill G.V.
      Laboratory risk factors for hospital mortality in acutely admitted patients.
      • Jones A.E.
      • Aborn L.S.
      • Kline J.A.
      Severity of emergency department hypotension predicts adverse hospital outcome.
      • Duckitt R.W.
      • Buxton-Thomas R.
      • Walker J.
      • et al.
      Worthing physiological scoring system: derivation and validation of a physiological early-warning system for medical admissions. An observational, population-based single-centre study.
      • Kellett J.
      • Deane B.
      The Simple Clinical Score predicts mortality for 30 days after admission to an acute medical unit.
      • Prytherch D.R.
      • Sirl J.S.
      • Schmidt P.
      • Featherstone P.I.
      • Weaver P.C.
      • Smith G.B.
      The use of routine laboratory data to predict in-hospital death in medical admissions.
      • Smith G.B.
      • Prytherch D.R.
      • Schmidt P.E.
      • et al.
      Should age be included as a component of track and trigger systems used to identify sick adult patients?.
      • Olsson T.
      • Terent A.
      • Lind L.
      Rapid Emergency Medicine score: a new prognostic tool for in-hospital mortality in nonsurgical emergency department patients.
      • Prytherch D.R.
      • Sirl J.S.
      • Weaver P.C.
      • Schmidt P.
      • Higgins B.
      • Sutton G.L.
      Towards a national clinical minimum data set for general surgery.
      • Subbe C.P.
      • Kruger M.
      • Rutherford P.
      • Gemmel L.
      Validation of a modified Early Warning Score in medical admissions.
      • Goodacre S.
      • Turner J.
      • Nicholl J.
      Prediction of mortality among emergency medical admissions.
      • Paterson R.
      • MacLeod D.C.
      • Thetford D.
      • et al.
      Prediction of in-hospital mortality and length of stay using an early warning scoring system: clinical audit.
      and unplanned ICU admission,
      • Jacques T.
      • Harrison G.A.
      • McLaws M.L.
      • Kilborn G.
      Signs of critical conditions and emergency responses (SOCCER): a model for predicting adverse events in the inpatient setting.
      • Subbe C.P.
      • Kruger M.
      • Rutherford P.
      • Gemmel L.
      Validation of a modified Early Warning Score in medical admissions.
      • Cuthbertson B.H.
      • Boroujerdi M.
      • McKie L.
      • Aucott L.
      • Prescott G.
      Can physiological variables and early warning scoring systems allow early recognition of the deteriorating surgical patient?.
      • Prytherch D.R.
      • Smith G.B.
      • Schmidt P.E.
      • Featherstone P.I.
      ViEWS – towards a national early warning score for detecting adult inpatient deterioration.
      and with increasing magnitude and number of derangements the likelihood of death is increased.
      • Fuhrmann L.
      • Lippert A.
      • Perner A.
      • Ostergaard D.
      Incidence, staff awareness and mortality of patients at risk on general wards.
      • Jacques T.
      • Harrison G.A.
      • McLaws M.L.
      • Kilborn G.
      Signs of critical conditions and emergency responses (SOCCER): a model for predicting adverse events in the inpatient setting.
      • Cretikos M.
      • Chen J.
      • Hillman K.
      • Bellomo R.
      • Finfer S.
      • Flabouris A.
      The objective medical emergency team activation criteria: a case-control study.
      • Smith G.B.
      • Prytherch D.R.
      • Schmidt P.E.
      • et al.
      Should age be included as a component of track and trigger systems used to identify sick adult patients?.
      • Buist M.
      • Bernard S.
      • Nguyen T.V.
      • Moore G.
      • Anderson J.
      Association between clinically abnormal observations and subsequent in-hospital mortality: a prospective study.
      • Goldhill D.R.
      • McNarry A.F.
      Physiological abnormalities in early warning scores are related to mortality in adult inpatients.
      • Harrison G.A.
      • Jacques T.
      • McLaws M.L.
      • Kilborn G.
      Combinations of early signs of critical illness predict in-hospital death-the SOCCER study (signs of critical conditions and emergency responses).
      • Bell M.B.
      • Konrad D.
      • Granath F.
      • Ekbom A.
      • Martling C.R.
      Prevalence and sensitivity of MET-criteria in a Scandinavian University Hospital.
      • Gardner-Thorpe J.
      • Love N.
      • Wrightson J.
      • Walsh S.
      • Keeling N.
      The value of Modified Early Warning Score (MEWS) in surgical in-patients: a prospective observational study.
      • Quarterman C.P.
      • Thomas A.N.
      • McKenna M.
      • McNamee R.
      Use of a patient information system to audit the introduction of modified early warning scoring.
      • Goldhill D.R.
      • McNarry A.F.
      • Hadjianastassiou V.G.
      • Tekkis P.P.
      The longer patients are in hospital before Intensive Care admission the higher their mortality.
      • Goldhill D.R.
      • McNarry A.F.
      • Mandersloot G.
      • McGinley A.
      A physiologically-based early warning score for ward patients: the association between score and outcome.
      • Boniatti M.M.
      • Azzolini N.
      • da Fonseca D.L.
      • et al.
      Prognostic value of the calling criteria in patients receiving a medical emergency team review.
      Even though abnormal physiology is common on general wards,
      • Harrison G.A.
      • Jacques T.C.
      • Kilborn G.
      • McLaws M.L.
      The prevalence of recordings of the signs of critical conditions and emergency responses in hospital wards – the SOCCER study.
      the measurement and documentation of vital signs is suboptimal.
      National Confidential Enquiry into Patient Outcome and Death. An acute problem?.
      • Kause J.
      • Smith G.
      • Prytherch D.
      • Parr M.
      • Flabouris A.
      • Hillman K.
      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.
      • Hillman K.
      • Chen J.
      • Cretikos M.
      • et al.
      Introduction of the medical emergency team (MET) system: a cluster-randomised controlled trial.
      • Hodgetts T.J.
      • Kenward G.
      • Vlachonikolis I.G.
      • Payne S.
      • Castle N.
      The identification of risk factors for cardiac arrest and formulation of activation criteria to alert a medical emergency team.
      • Hall S.
      • Williams E.
      • Richards S.
      • Subbe C.
      • Gemmell L.
      Waiting to exhale: critical care outreach and recording of ventilatory frequency.
      • McBride J.
      • Knight D.
      • Piper J.
      • Smith G.
      Long-term effect of introducing an early warning score on respiratory rate charting on general wards.
      • McGain F.
      • Cretikos M.A.
      • Jones D.
      • et al.
      Documentation of clinical review and vital signs after major surgery.
      To assist in the early detection of critical illness, each patient should have a documented plan for vital signs monitoring including which physiological measurements needs no be undertaken and frequency.
      • DeVita M.A.
      • Smith G.B.
      • Adam S.K.
      • et al.
      “Identifying the hospitalised patient in crisis” – a consensus conference on the afferent limb of rapid response systems.
      • Excellence NIfHaC
      NICE clinical guideline 50. Acutely ill patients in hospital: recognition of and response to acute illness in adults in hospital.
      Many hospitals use early warning scores (EWS) or calling criteria to identify ward patients needing escalation of care,
      • Hillman K.
      • Chen J.
      • Cretikos M.
      • et al.
      Introduction of the medical emergency team (MET) system: a cluster-randomised controlled trial.
      • Hodgetts T.J.
      • Kenward G.
      • Vlachonikolis I.G.
      • Payne S.
      • Castle N.
      The identification of risk factors for cardiac arrest and formulation of activation criteria to alert a medical emergency team.
      • McBride J.
      • Knight D.
      • Piper J.
      • Smith G.
      Long-term effect of introducing an early warning score on respiratory rate charting on general wards.
      • Goldhill D.R.
      • Worthington L.
      • Mulcahy A.
      • Tarling M.
      • Sumner A.
      The patient-at-risk team: identifying and managing seriously ill ward patients.
      • Subbe C.P.
      • Davies R.G.
      • Williams E.
      • Rutherford P.
      • Gemmell L.
      Effect of introducing the Modified Early Warning score on clinical outcomes, cardio-pulmonary arrests and intensive care utilisation in acute medical admissions.
      • Armitage M.
      • Eddleston J.
      • Stokes T.
      Recognising and responding to acute illness in adults in hospital: summary of NICE guidance.
      • Chen J.
      • Hillman K.
      • Bellomo R.
      • Flabouris A.
      • Finfer S.
      • Cretikos M.
      The impact of introducing medical emergency team system on the documentations of vital signs.
      • Odell M.
      • Rechner I.J.
      • Kapila A.
      • et al.
      The effect of a critical care outreach service and an early warning scoring system on respiratory rate recording on the general wards.
      and this increases vital signs monitoring.
      • McBride J.
      • Knight D.
      • Piper J.
      • Smith G.
      Long-term effect of introducing an early warning score on respiratory rate charting on general wards.
      • Chen J.
      • Hillman K.
      • Bellomo R.
      • Flabouris A.
      • Finfer S.
      • Cretikos M.
      The impact of introducing medical emergency team system on the documentations of vital signs.
      • Odell M.
      • Rechner I.J.
      • Kapila A.
      • et al.
      The effect of a critical care outreach service and an early warning scoring system on respiratory rate recording on the general wards.
      These calling criteria or ‘track and trigger’ systems include single-parameter systems, multiple-parameter systems, aggregate weighted scoring systems or combination systems.
      Critical care outreach 2003: progress in developing services. The National Outreach Report.
      Aggregate weighted track and trigger systems offer a graded escalation of care, whereas single parameter track and trigger systems provide an all-or-nothing response. Simpler systems may have advantages over more complex ones.
      • Subbe C.P.
      • Gao H.
      • Harrison D.A.
      Reproducibility of physiological track-and-trigger warning systems for identifying at-risk patients on the ward.
      • Jarvis S.
      • Kovacs C.
      • Briggs J.
      • et al.
      Can binary early warning scores perform as well as standard early warning scores for discriminating a patient's risk of cardiac arrest, death or unanticipated intensive care unit admission?.
      Nurse concern may also be an important predictor of patient deterioration.
      • Douw G.
      • Schoonhoven L.
      • Holwerda T.
      • et al.
      Nurses’ worry or concern and early recognition of deteriorating patients on general wards in acute care hospitals: a systematic review.
      • Santiano N.
      • Young L.
      • Hillman K.
      • et al.
      Analysis of medical emergency team calls comparing subjective to “objective” call criteria.
      • Herod R.
      • Frost S.A.
      • Parr M.
      • Hillman K.
      • Aneman A.
      Long term trends in medical emergency team activations and outcomes.
      The use of an aggregate score based on a number of vital sign abnormalities appears more important than abnormalities in a single criteria.
      • Tirkkonen J.
      • Olkkola K.T.
      • Huhtala H.
      • Tenhunen J.
      • Hoppu S.
      Medical emergency team activation: performance of conventional dichotomised criteria versus national early warning score.
      • Jarvis S.
      • Kovacs C.
      • Briggs J.
      • et al.
      Aggregate National Early Warning Score (NEWS) values are more important than high scores for a single vital signs parameter for discriminating the risk of adverse outcomes.
      Aggregate-weighted scoring systems vary in their performance and in which endpoint they predict.
      • Smith G.B.
      • Prytherch D.R.
      • Schmidt P.E.
      • Featherstone P.I.
      Review and performance evaluation of aggregate weighted ‘track and trigger’ systems.
      • Prytherch D.R.
      • Smith G.B.
      • Schmidt P.E.
      • Featherstone P.I.
      ViEWS – towards a national early warning score for detecting adult inpatient deterioration.
      • Smith G.B.
      • Prytherch D.R.
      • Meredith P.
      • Schmidt P.E.
      • Featherstone P.I.
      The ability of the National Early Warning Score (NEWS) to discriminate patients at risk of early cardiac arrest, unanticipated intensive care unit admission, and death.
      In older (>65 year) patients, who represent the largest group of IHCA patients,
      • Nadkarni V.M.
      • Larkin G.L.
      • Peberdy M.A.
      • et al.
      First documented rhythm and clinical outcome from in-hospital cardiac arrest among children and adults.
      signs of deterioration before cardiac arrest are often blunted, and the predictive value of the Modified Early Warning Score (MEWS) progressively decreases with increasing patient age.
      • Churpek M.M.
      • Yuen T.C.
      • Winslow C.
      • Hall J.
      • Edelson D.P.
      Differences in vital signs between elderly and nonelderly patients prior to ward cardiac arrest.
      The design of vital signs charts
      • Chatterjee M.T.
      • Moon J.C.
      • Murphy R.
      • McCrea D.
      The “OBS” chart: an evidence based approach to re-design of the patient observation chart in a district general hospital setting.
      • Preece M.H.
      • Hill A.
      • Horswill M.S.
      • Watson M.O.
      Supporting the detection of patient deterioration: observation chart design affects the recognition of abnormal vital signs.
      or the use of technology
      • Smith G.B.
      • Prytherch D.R.
      • Schmidt P.
      • et al.
      Hospital-wide physiological surveillance-a new approach to the early identification and management of the sick patient.
      • Bellomo R.
      • Ackerman M.
      • Bailey M.
      • et al.
      A controlled trial of electronic automated advisory vital signs monitoring in general hospital wards.
      • Evans R.S.
      • Kuttler K.G.
      • Simpson K.J.
      • et al.
      Automated detection of physiologic deterioration in hospitalized patients.
      may have an important role in the detection of deterioration and the escalation of care, but these require further study. Possible benefits include increased vital signs recording,
      • Mitchell I.A.
      • McKay H.
      • Van Leuvan C.
      • et al.
      A prospective controlled trial of the effect of a multi-faceted intervention on early recognition and intervention in deteriorating hospital patients.
      improved identification of signs of deterioration,
      • Chatterjee M.T.
      • Moon J.C.
      • Murphy R.
      • McCrea D.
      The “OBS” chart: an evidence based approach to re-design of the patient observation chart in a district general hospital setting.
      • Preece M.H.
      • Hill A.
      • Horswill M.S.
      • Watson M.O.
      Supporting the detection of patient deterioration: observation chart design affects the recognition of abnormal vital signs.
      • Evans R.S.
      • Kuttler K.G.
      • Simpson K.J.
      • et al.
      Automated detection of physiologic deterioration in hospitalized patients.
      reduced time to team activation
      • Bellomo R.
      • Ackerman M.
      • Bailey M.
      • et al.
      A controlled trial of electronic automated advisory vital signs monitoring in general hospital wards.
      and improved patient outcomes.
      • Bellomo R.
      • Ackerman M.
      • Bailey M.
      • et al.
      A controlled trial of electronic automated advisory vital signs monitoring in general hospital wards.
      • Schmidt P.E.
      • Meredith P.
      • Prytherch D.R.
      • et al.
      Impact of introducing an electronic physiological surveillance system on hospital mortality.

      Calling for help and the response to critical illness

      Nursing staff and junior doctors often find it difficult to ask for help or escalate treatment as they feel their clinical judgement may be criticised.
      • Azzopardi P.
      • Kinney S.
      • Moulden A.
      • Tibballs J.
      Attitudes and barriers to a Medical Emergency Team system at a tertiary paediatric hospital.
      • Radeschi G.
      • Urso F.
      • Campagna S.
      • et al.
      Factors affecting attitudes and barriers to a medical emergency team among nurses and medical doctors: a multi-centre survey.
      • Bagshaw S.M.
      • Mondor E.E.
      • Scouten C.
      • et al.
      A survey of nurses’ beliefs about the medical emergency team system in a canadian tertiary hospital.
      • Shearer B.
      • Marshall S.
      • Buist M.D.
      • et al.
      What stops hospital clinical staff from following protocols? An analysis of the incidence and factors behind the failure of bedside clinical staff to activate the rapid response system in a multi-campus Australian metropolitan healthcare service.
      In addition, there is a common belief, especially amongst younger staff, that the patient's primary team should be capable of dealing with problems close to their area of specialty.
      • Shearer B.
      • Marshall S.
      • Buist M.D.
      • et al.
      What stops hospital clinical staff from following protocols? An analysis of the incidence and factors behind the failure of bedside clinical staff to activate the rapid response system in a multi-campus Australian metropolitan healthcare service.
      It is logical that hospitals should ensure all staff are empowered to call for help and also trained to use structured communication tools such as RSVP (reason-story-vital signs-plan)
      • Featherstone P.
      • Chalmers T.
      • Smith G.B.
      RSVP: a system for communication of deterioration in hospital patients.
      or SBAR (situation-background-assessment-recommendation)
      • Marshall S.
      • Harrison J.
      • Flanagan B.
      The teaching of a structured tool improves the clarity and content of interprofessional clinical communication.
      tools to ensure effective inter-professional communication. However, recent research suggests that structured communication tools are rarely used in clinical practice.
      • Ludikhuize J.
      • de Jonge E.
      • Goossens A.
      Measuring adherence among nurses one year after training in applying the Modified Early Warning Score and Situation-Background-Assessment-Recommendation instruments.
      The response to patients who are critically ill or who are at risk of becoming critically ill is now usually provided by a medical emergency team (MET), rapid response team (RRT), or critical care outreach team (CCOT).
      • Lee A.
      • Bishop G.
      • Hillman K.M.
      • Daffurn K.
      The Medical Emergency Team.
      • Devita M.A.
      • Bellomo R.
      • Hillman K.
      • et al.
      Findings of the first consensus conference on medical emergency teams.
      • Ball C.
      • Kirkby M.
      • Williams S.
      Effect of the critical care outreach team on patient survival to discharge from hospital and readmission to critical care: non-randomised population based study.
      • Jones D.A.
      • DeVita M.A.
      • Bellomo R.
      Rapid-response teams.
      These replace or coexist with traditional cardiac arrest teams, which typically respond to patients already in cardiac arrest. MET/RRT usually comprise medical and nursing staff from intensive care and general medicine, who respond to specific calling criteria. Any member of the healthcare team can initiate a MET/RRT/CCOT call. In some hospitals, the patient, and their family and friends, are also encouraged to activate the team.
      • Zenker P.
      • Schlesinger A.
      • Hauck M.
      • et al.
      Implementation and impact of a rapid response team in a children's hospital.
      • Dean B.S.
      • Decker M.J.
      • Hupp D.
      • Urbach A.H.
      • Lewis E.
      • Benes-Stickle J.
      Condition HELP: a pediatric rapid response team triggered by patients and parents.
      • Ray E.M.
      • Smith R.
      • Massie S.
      • et al.
      Family alert: implementing direct family activation of a pediatric rapid response team.
      Team interventions often involve simple tasks such as starting oxygen therapy and intravenous fluids.
      • Kenward G.
      • Castle N.
      • Hodgetts T.
      • Shaikh L.
      Evaluation of a medical emergency team one year after implementation.
      • Chan P.S.
      • Khalid A.
      • Longmore L.S.
      • Berg R.A.
      • Kosiborod M.
      • Spertus J.A.
      Hospital-wide code rates and mortality before and after implementation of a rapid response team.
      • Dacey M.J.
      • Mirza E.R.
      • Wilcox V.
      • et al.
      The effect of a rapid response team on major clinical outcome measures in a community hospital.
      • Story D.A.
      • Shelton A.C.
      • Poustie S.J.
      • Colin-Thome N.J.
      • McNicol P.L.
      The effect of critical care outreach on postoperative serious adverse events.
      • Story D.A.
      • Shelton A.C.
      • Poustie S.J.
      • Colin-Thome N.J.
      • McIntyre R.E.
      • McNicol P.L.
      Effect of an anaesthesia department led critical care outreach and acute pain service on postoperative serious adverse events.
      However, post-hoc analysis of the MERIT study data suggests that nearly all MET calls required ‘critical care-type’ interventions.
      • Flabouris A.
      • Chen J.
      • Hillman K.
      • Bellomo R.
      • Finfer S.
      Timing and interventions of emergency teams during the MERIT study.
      The MET, RRT or CCOT is often also involved in discussions regarding ‘do not attempt cardiopulmonary resuscitation’ (DNACPR) or end-of-life plans.
      • Jones D.A.
      • Bagshaw S.M.
      • Barrett J.
      • et al.
      The role of the medical emergency team in end-of-life care: a multicenter, prospective, observational study.
      • Downar J.
      • Barua R.
      • Rodin D.
      • et al.
      Changes in end of life care 5 years after the introduction of a rapid response team: a multicentre retrospective study.
      • Coventry C.
      • Flabouris A.
      • Sundararajan K.
      • Cramey T.
      Rapid response team calls to patients with a pre-existing not for resuscitation order.
      • Sulistio M.
      • Franco M.
      • Vo A.
      • Poon P.
      • William L.
      Hospital rapid response team and patients with life-limiting illness: a multicentre retrospective cohort study.
      • Tan L.H.
      • Delaney A.
      Medical emergency teams and end-of-life care: a systematic review.
      • Smith R.L.
      • Hayashi V.N.
      • Lee Y.I.
      • Navarro-Mariazeta L.
      • Felner K.
      The medical emergency team call: a sentinel event that triggers goals of care discussion.
      • Downar J.
      • Rodin D.
      • Barua R.
      • et al.
      Rapid response teams, do not resuscitate orders, and potential opportunities to improve end-of-life care: a multicentre retrospective study.
      Recently, attempts have been made to develop a screening tool to identify patients at the end of life and quantify the risk of death in order to minimise prognostic uncertainty and avoid potentially harmful and futile treatments.
      • Cardona-Morrell M.
      • Hillman K.
      Development of a tool for defining and identifying the dying patient in hospital: Criteria for Screening and Triaging to Appropriate aLternative care (CriSTAL).
      Studying the effect of the MET/RRT/CCOT systems on patient outcomes is difficult because of the complex nature of the intervention. During the period of most studies of rapid response teams, there has been a major international focus on improving other aspects of patient safety, e.g. hospital acquired infections, earlier treatment of sepsis and better medication management, all of which have the potential to influence patient deterioration and may have a beneficial impact on reducing cardiac arrests and hospital deaths. Most studies on RRT/MET systems to date originate from the USA and Australia and the systems effectiveness in other health care systems in not clear.
      • Sandroni C.
      • D’Arrigo S.
      • Antonelli M.
      Rapid response systems: are they really effective?.
      A well-designed, cluster-randomised controlled trial of the MET system (MERIT study) involving 23 hospitals
      • Hillman K.
      • Chen J.
      • Cretikos M.
      • et al.
      Introduction of the medical emergency team (MET) system: a cluster-randomised controlled trial.
      did not show a reduction in cardiac arrest rate after introduction of a MET when analysed on an intention-to-treat basis. Both the control and MET groups demonstrated improved outcome compared to baseline. Post hoc analysis of the MERIT study showed there was a decrease in cardiac arrest and unexpected mortality rate with increased activation of the MET system.
      • Chen J.
      • Bellomo R.
      • Flabouris A.
      • Hillman K.
      • Finfer S.
      The relationship between early emergency team calls and serious adverse events.
      The evidence from predominantly single centre observational studies is inconclusive, with some studies showing reduced numbers of cardiac arrests after MET/RRT implementation
      • Bellomo R.
      • Goldsmith D.
      • Uchino S.
      • et al.
      A prospective before-and-after trial of a medical emergency team.
      • DeVita M.A.
      • Braithwaite R.S.
      • Mahidhara R.
      • Stuart S.
      • Foraida M.
      • Simmons R.L.
      Use of medical emergency team responses to reduce hospital cardiopulmonary arrests.
      • Dacey M.J.
      • Mirza E.R.
      • Wilcox V.
      • et al.
      The effect of a rapid response team on major clinical outcome measures in a community hospital.
      • Baxter A.D.
      • Cardinal P.
      • Hooper J.
      • Patel R.
      Medical emergency teams at The Ottawa Hospital: the first two years.
      • Benson L.
      • Mitchell C.
      • Link M.
      • Carlson G.
      • Fisher J.
      Using an advanced practice nursing model for a rapid response team.
      • Bertaut Y.
      • Campbell A.
      • Goodlett D.
      Implementing a rapid-response team using a nurse-to-nurse consult approach.
      • Buist M.D.
      • Moore G.E.
      • Bernard S.A.
      • Waxman B.P.
      • Anderson J.N.
      • Nguyen T.V.
      Effects of a medical emergency team on reduction of incidence of and mortality from unexpected cardiac arrests in hospital: preliminary study.
      • Buist M.
      • Harrison J.
      • Abaloz E.
      • Van Dyke S.
      Six year audit of cardiac arrests and medical emergency team calls in an Australian outer metropolitan teaching hospital.
      • Chamberlain B.
      • Donley K.
      • Maddison J.
      Patient outcomes using a rapid response team.
      • Hatler C.
      • Mast D.
      • Bedker D.
      • et al.
      Implementing a rapid response team to decrease emergencies outside the ICU: one hospital's experience.
      • Jones D.
      • Bellomo R.
      • Bates S.
      • et al.
      Long term effect of a medical emergency team on cardiac arrests in a teaching hospital.
      • Jones D.
      • Bellomo R.
      • Bates S.
      • et al.
      Patient monitoring and the timing of cardiac arrests and medical emergency team calls in a teaching hospital.
      • Moldenhauer K.
      • Sabel A.
      • Chu E.S.
      • Mehler P.S.
      Clinical triggers: an alternative to a rapid response team.
      • Offner P.J.
      • Heit J.
      • Roberts R.
      Implementation of a rapid response team decreases cardiac arrest outside of the intensive care unit.
      • Gould D.
      Promoting patient safety: the rapid medical response team.
      • Jolley J.
      • Bendyk H.
      • Holaday B.
      • Lombardozzi K.A.
      • Harmon C.
      Rapid response teams: do they make a difference?.
      • Konrad D.
      • Jaderling G.
      • Bell M.
      • Granath F.
      • Ekbom A.
      • Martling C.R.
      Reducing in-hospital cardiac arrests and hospital mortality by introducing a medical emergency team.
      • Simmes F.M.
      • Schoonhoven L.
      • Mintjes J.
      • Fikkers B.G.
      • van der Hoeven J.G.
      Incidence of cardiac arrests and unexpected deaths in surgical patients before and after implementation of a rapid response system.
      • Howell M.D.
      • Ngo L.
      • Folcarelli P.
      • et al.
      Sustained effectiveness of a primary-team-based rapid response system.
      • Beitler J.R.
      • Link N.
      • Bails D.B.
      • Hurdle K.
      • Chong D.H.
      Reduction in hospital-wide mortality after implementation of a rapid response team: a long-term cohort study.
      • Santamaria J.
      • Tobin A.
      • Holmes J.
      Changing cardiac arrest and hospital mortality rates through a medical emergency team takes time and constant review.
      • Rothberg M.B.
      • Belforti R.
      • Fitzgerald J.
      • Friderici J.
      • Keyes M.
      Four years’ experience with a hospitalist-led medical emergency team: an interrupted time series.
      • Lighthall G.K.
      • Parast L.M.
      • Rapoport L.
      • Wagner T.H.
      Introduction of a rapid response system at a United States veterans affairs hospital reduced cardiac arrests.
      • Chen J.
      • Ou L.
      • Hillman K.
      • et al.
      The impact of implementing a rapid response system: a comparison of cardiopulmonary arrests and mortality among four teaching hospitals in Australia.
      • Jones D.
      • George C.
      • Hart G.K.
      • Bellomo R.
      • Martin J.
      Introduction of medical emergency teams in Australia and New Zealand: a multi-centre study.
      • Al-Qahtani S.
      • Al-Dorzi H.M.
      • Tamim H.M.
      • et al.
      Impact of an intensivist-led multidisciplinary extended rapid response team on hospital-wide cardiopulmonary arrests and mortality.
      and some studies failing to show a reduction
      • Kenward G.
      • Castle N.
      • Hodgetts T.
      • Shaikh L.
      Evaluation of a medical emergency team one year after implementation.
      • Chan P.S.
      • Khalid A.
      • Longmore L.S.
      • Berg R.A.
      • Kosiborod M.
      • Spertus J.A.
      Hospital-wide code rates and mortality before and after implementation of a rapid response team.
      • Story D.A.
      • Shelton A.C.
      • Poustie S.J.
      • Colin-Thome N.J.
      • McNicol P.L.
      The effect of critical care outreach on postoperative serious adverse events.
      • Story D.A.
      • Shelton A.C.
      • Poustie S.J.
      • Colin-Thome N.J.
      • McIntyre R.E.
      • McNicol P.L.
      Effect of an anaesthesia department led critical care outreach and acute pain service on postoperative serious adverse events.
      • Bristow P.J.
      • Hillman K.M.
      • Chey T.
      • et al.
      Rates of in-hospital arrests, deaths and intensive care admissions: the effect of a medical emergency team.
      • King E.
      • Horvath R.
      • Shulkin D.J.
      Establishing a rapid response team (RRT) in an academic hospital: one year's experience.
      • McFarlan S.J.
      • Hensley S.
      Implementation and outcomes of a rapid response team.
      • Rothschild J.M.
      • Woolf S.
      • Finn K.M.
      • et al.
      A controlled trial of a rapid response system in an academic medical center.
      . However, systematic reviews, meta-analyses and multicentre studies do suggest that RRT/MET systems reduce rates of cardiopulmonary arrest and lower hospital mortality rates.
      • Chan P.S.
      • Jain R.
      • Nallmothu B.K.
      • Berg R.A.
      • Sasson C.
      Rapid response teams: a systematic review and meta-analysis.
      • Winters B.D.
      • Weaver S.J.
      • Pfoh E.R.
      • Yang T.
      • Pham J.C.
      • Dy S.M.
      Rapid-response systems as a patient safety strategy: a systematic review.
      • Chen J.
      • Ou L.
      • Hillman K.M.
      • et al.
      Cardiopulmonary arrest and mortality trends, and their association with rapid response system expansion.
      Concern has been expressed about MET activity leading to potential adverse events resulting from staff leaving normal duties to attend MET calls. Research suggests that although MET calls may cause disruption to normal hospital routines and inconvenience to staff, no major patient harm follows.
      • Cheung W.
      • Sahai V.
      • et al.
      Concord Medical Emergency Team Incidents Study I
      Incidents resulting from staff leaving normal duties to attend medical emergency team calls.

      Appropriate placement of patients

      Ideally, the sickest patients should be admitted to an area that can provide the greatest supervision and the highest level of organ support and nursing care. International organisations have offered definitions of levels of care and produced admission and discharge criteria for high dependency units (HDUs) and ICUs.
      Guidelines for the utilisation of intensive care units. European Society of Intensive Care Medicine.
      • Haupt M.T.
      • Bekes C.E.
      • Brilli R.J.
      • et al.
      Guidelines on critical care services and personnel: Recommendations based on a system of categorization of three levels of care.