- Email: [email protected]
Monitoring the monitors—beyond risk management
‘‘I would have everie man write what he knowes and no more.’’—Montaigne
BRITISH JOURNAL OF ANAESTHESIA Volume 97, Number 1, July 2006 British Journal of Anaesthesia 97 (1): 1–3 (2006) doi:10.1093/bja/ael139
Editorial Monitoring the monitors—beyond risk management vigilance’. As early as 1947, it was shown that observation could not detect cyanosis reliably.1 In the 1980s, studies proved the inadequacy of reliably detecting hypoxia or adequacy of ventilation2 3 by clinical means alone, and it became clear that more sophisticated aids were required. Advances in technology made it possible to introduce pulse oximetry and capnography into clinical practice and it was immediately evident that these monitors would supplement the deficiencies in our clinical abilities. These devices were incorporated into the recommendations for standards of monitoring by ASA and the Association of Anaesthetists of Great Britain and Ireland.4 5 Studies in the 1990s convincingly proved that the use of pulse oximetry and capnography were crucial in the prevention and early detection of many unwanted events, and that they significantly reduced the number of critical incidents.6–10 For this reason, in the UK by the mid-1990s, the recommended monitoring standards came to be considered mandatory for safety and risk management, and lack of these during anaesthesia had become indefensible in cases of medical litigation.11 However, it must be remembered that in some parts of the world these standards may still be considered an unaffordable ‘luxury’. The minimum acceptable standard of monitoring now includes ECG, non-invasive arterial pressure, pulse oximetry, capnography and gas analysis, while a nerve stimulator and a means of measuring temperature should be immediately available. In an intensive care unit (ICU), monitoring of invasive arterial pressure, central venous pressure, blood gases, biochemistry and detailed ventilatory parameters are now standard. Monitoring devices recently introduced or in development, aim to give much more detailed information about the patient than has been possible previously. These include devices that can assess depth of sedation and anaesthesia, haemodynamic variables such as stroke volume, cardiac output and systemic vascular resistance, and cerebral haemodynamic and metabolic variables. However, for any monitoring device to become ‘standard’ it must not only be reliable and improve safety, but must also lead to better patient care, clinical outcome
Ó The Board of Management and Trustees of the British Journal of Anaesthesia 2006. All rights reserved. For Permissions, please e-mail: [email protected]
Downloaded from http://bja.oxfordjournals.org/ at Lakehead University on March 18, 2015
Monitoring, to health care professionals and in particular anaesthetists, usually means the continuous measurement of patient variables over time. However, the word monitor derives from the Latin monere (to warn) and modern English dictionaries include almost a dozen different connotations. These range from an observational warning or recording device (or individual) to audiovisual terminology, a senior school pupil and types of lizard or warship. In a similar way, the term monitor in anaesthesia, critical care, pain management or perioperative medicine actually encompasses a variety of technologies that address diverse but overlapping aspects of anaesthesia and medical care. Over the past two decades, these technologies have advanced greatly and the availability of monitoring devices has multiplied exponentially. This has occurred in conjunction with the developments in electronics, computing, information technology and mobile communications, which has characterized the past 20 yr. This issue of the British Journal of Anaesthesia is based on the symposium held in March 2006 and organized jointly by The Royal College of Anaesthetists and British Journal of Anaesthesia. The articles range from the interaction between humans and machines, new and emerging technologies and their application not only inside and outside the operating room but also at the extremes of environments where medical care may be needed. In order to fully understand the panoply of modern monitoring, we should remember the progress made in the very recent past. When exactly instrumental monitoring started in anaesthetic practice is unclear, but the core guiding principle of the profession of anaesthesia has always been ‘For some must watch, while some must sleep’ (Hamlet, W. Shakespeare). ‘Vigilance’ has been the motto of the ASA since it was founded in 1905. While some of us can still remember the days up to the mid-1980s when this vigilance, in practical terms, was restricted to an anaesthetist’s utilization of senses by inspection or palpation for clinical signs (observation of the patient’s colour with a finger on the pulse), there has been convincing evidence that our human senses by themselves, are not reliable in keeping ‘eternal
Editorial
the monitoring devices of the future will no longer be confined to machines which simply warn the clinician or record clinical events. They will be capable of controlling clinical care in a variety of forms by engendering action by the clinician or by initiating an action on their own. New ventilators are already capable of monitoring lung mechanics and automatically adjusting the ventilator settings to prevent ventilator associated lung injury or to aid weaning.19 The integration of a pharmacokinetic-based anaesthetic infusion pump with a depth of anaesthesia monitor to determine individual dose–response curves to the anaesthetic which could feed back to the pump and tailor the anaesthetic accordingly, is not far away.12 Similar systems could also control the administration of fluids or vasoactive drugs in critical care according to patient’s cardiovascular data and guided by protocols set by the clinician. An integrated cardiovascular monitor might incorporate the data from existing monitors on a patient’s cardiac rhythm, contractility, cardiac output, oxygen flux and organ or tissue perfusion to guide therapy, and some of the currently available monitors are close to this capability. These types of monitor would enable patient monitoring and automated correction of physiological abnormalities to occur together, freeing the clinician to concentrate on diagnosis and other aspects of therapy. If validated, these types of monitors could decrease the element of human error, which underlies many medical mishaps or critical incidents. However, technology is not perfect, and most clinicians are aware of the limitations of protocol-driven medicine. Humans are infinitely variable in their responses to disease and medical interventions and will technology be able to reliably account for this? Medicine is full of uncertainties and no monitor will always be 100% accurate and reliable. How many of us have been in a situation when the monitor tells us something is wrong but our instincts tell us otherwise? Would an over-reliance on new technology diminish our clinical acumen or instinct over time? What if the ‘smart’ monitor integrated with the anaesthesia or critical care management system acted to produce patient harm? Who would be responsible—the machine, the manufacturer or the clinician? Despite our clinical frailties, patients rightly expect their doctors to be human as well as humane, and may be uncomfortable if therapy was being directed by a machine. Finally, new technology is only better if patients’ outcome is improved. We clinicians must be aware of developments and be in a position to direct them—we should continue to monitor the monitors. J. P. Thompson1* R. P. Mahajan2 1
University Department of Cardiovascular Sciences Division of Anaesthesia Critical Care and Pain Management Leicester Royal Infirmary
2
Downloaded from http://bja.oxfordjournals.org/ at Lakehead University on March 18, 2015
and be cost-effective. Furthermore, the monitoring device should ideally integrate with the ‘standard’ monitoring and management plan. For example, in this issue Bruhn and colleagues12 review the role of depth of anaesthesia monitoring in avoiding both awareness and excessive depth of anaesthesia to thus improve outcome in patients undergoing anaesthesia or monitored sedation. They correctly suggest that for these to become part of standard care, awareness should be included in outcome measures. Any cost–benefit analysis should include the possible savings on drug usage, recovery times, complications of ‘deep’ anaesthesia and hospital stay. This attitude to the introduction of monitoring is not universal. For example, measurement of intracranial pressure (ICP) is considered an essential part of monitoring for neurosurgical and neurological patients, despite a lack of grade 1 evidence that ICP measurement or estimation of cerebral blood flow has any impact on outcome after acute brain injury.13 New technologies including on-line cerebral microdialysis14 and novel imaging modalities are being actively investigated and, although they have considerable potential, their role is not yet established. Another approach is to combine information from new and existing technologies to produce multimodal monitoring. There is some evidence that outcome after head injury is improved if treatment is guided by ICP monitoring in combination with measurements of brain oxygen tension.15 Monitoring has changed our practice in other ways. Kneeshaw16 argues that transoesophageal echocardiography has significantly changed the role of anaesthetists experienced in its use to become indispensable in the diagnosis and management of circulatory insufficiency in the operating room and ICU. Intraoperative echocardiography is more than a monitor, as surgeons increasingly rely on the information it provides to direct their surgical procedure. This situation has arisen as a result of the development of a specific training and accreditation programme which is unique amongst monitoring modalities. Whereas a number of recent studies have linked some aspects of monitoring with improved outcomes, the limitations of monitoring have also become apparent. Young and Griffiths17 correctly observe that more information is not always better and monitoring will only benefit the patient if there is an effective treatment for the underlying cause. The right information must be collected at the right time, interpreted correctly and acted upon appropriately. One way to overcome these delays is to combine the information from several patients or systems. Tarassenko and colleagues18 review the role of integrated monitoring systems in a ward setting in picking up early warning signs and acting on them quickly. Despite the apparent failure in studies of some monitoring devices to produce clear clinical benefits, we should not be deterred, as the availability of improved monitoring techniques can potentially lead to dramatic changes in clinical practice. The reviews in this educational issue indicate that
Editorial
Leicester, UK 2 University Hospitals NHS Trust Queen’s Medical Centre Nottingham, UK *E-mail: [email protected]
10
11
References 12
13 14 15
16 17
18
19
3
Downloaded from http://bja.oxfordjournals.org/ at Lakehead University on March 18, 2015
1 Comroe JH, Bothelo S. The unreliability of cyanosis in the recognition of arterial anoxemia. Am J Med Sci 1947; 214: 1–2 2 Weingarten M. Anaesthetic and ventilator mishaps: prevention and direction. Crit Care Med 1986; 14: 1084–6 3 Semmes BJ, Tobin MJ, Snyder JV, Grenvik A. Subjective and objective measurement of tidal volume in critically ill patients. Chest 1985; 87: 577–9 4 Eichhorn JH, Cooper JB, Cullen DJ, Maier WR, Philip JH, Seeman RG. Standards of patient monitoring during anaesthesia at Harward Medical School. JAMA 1986; 256: 1017–20 5 Recommendations for Standards of Monitoring during Anaesthesia and Recovery. Association of Anaesthetists of Great Britain and Ireland, 2000 6 Keenan RL, Boyan CP. Decreasing frequency of anaesthetic cardiac arrests. J Clin Anesth 1991; 3: 354–7 7 Webb RK, van der Walt JH, Runciman WB, et al. Which monitor? An analysis of 2000 incident reports. Anaesth Intensive Care 1993; 21: 529–42 8 McKay WP, Noble WH. Critical incidents detected by pulse oximetry during anaesthesia. Can J Anaesth 1988; 35: 265–9 9 Cullen DJ, Nemaskal JR, Cooper JB, Zaslavsky A, Dwyer MJ. Effect of pulse oximetry, age and ASA physical status on the frequency
of patients admitted unexpectedly to a post-operative intensive care unit. Anesth Analg 1992; 74: 181–8 Moller JT, Johannessen NW, Espersen K, et al. Randomized evaluation of pulse oximetry in 20,802 patients. II. Perioperative events and postoperative complications. Anesthesiology 1993; 78: 444–53 Blitt CD. History and philosophy of monitoring. In: Lake CL, Hines RL, Blitt CD, eds. Clinical Monitoring: Practical Applications for Anaesthesia and Critical Care. New York: WB Saunders Company, 2001 Bruhn J, Myles PS, Sneyd JR, Struys MMRF. Depth of anaesthesia monitoring: what’s available, what’s validated and what’s next. Br J Anaesth 2006; 97: 85–94 Steiner LA, Andrews PJD. Monitoring the injured brain: ICP and CBF. Br J Anaesth 2006; 97: 26–38 Tisdall MM, Smith M. Cerebral microdialysis: research technique or clinical tool. Br J Anaesth 2006; 97: 18–25 Stiefel MF, Spiotta A, Gracias VH, et al. Reduced mortality rate in patients with severe traumatic brain injury treated with brain tissue oxygen monitoring. J Neurosurg 2005; 103: 805–11 Kneeshaw JD. Transoesophageal echocardiography (TOE) in the operating room. Br J Anaesth 2006; 97: 77–84 Young D, Griffiths J. Clinical trials of monitoring in anaesthesia, critical care and acute ward care: a review. Br J Anaesth 2006; 97: 39–45 Tarassenko L, Hann A, Young D. Integrated monitoring and analysis for early warning of patient deterioration. Br J Anaesth 2006; 97: 64–8 Macnaughton PD. New ventilators for the ICU: usefulness of lung performance reporting. Br J Anaesth 2006; 97: 57–63
BRITISH JOURNAL OF ANAESTHESIA Volume 97, Number 1, July 2006 British Journal of Anaesthesia 97 (1): 1–3 (2006) doi:10.1093/bja/ael139
Editorial Monitoring the monitors—beyond risk management vigilance’. As early as 1947, it was shown that observation could not detect cyanosis reliably.1 In the 1980s, studies proved the inadequacy of reliably detecting hypoxia or adequacy of ventilation2 3 by clinical means alone, and it became clear that more sophisticated aids were required. Advances in technology made it possible to introduce pulse oximetry and capnography into clinical practice and it was immediately evident that these monitors would supplement the deficiencies in our clinical abilities. These devices were incorporated into the recommendations for standards of monitoring by ASA and the Association of Anaesthetists of Great Britain and Ireland.4 5 Studies in the 1990s convincingly proved that the use of pulse oximetry and capnography were crucial in the prevention and early detection of many unwanted events, and that they significantly reduced the number of critical incidents.6–10 For this reason, in the UK by the mid-1990s, the recommended monitoring standards came to be considered mandatory for safety and risk management, and lack of these during anaesthesia had become indefensible in cases of medical litigation.11 However, it must be remembered that in some parts of the world these standards may still be considered an unaffordable ‘luxury’. The minimum acceptable standard of monitoring now includes ECG, non-invasive arterial pressure, pulse oximetry, capnography and gas analysis, while a nerve stimulator and a means of measuring temperature should be immediately available. In an intensive care unit (ICU), monitoring of invasive arterial pressure, central venous pressure, blood gases, biochemistry and detailed ventilatory parameters are now standard. Monitoring devices recently introduced or in development, aim to give much more detailed information about the patient than has been possible previously. These include devices that can assess depth of sedation and anaesthesia, haemodynamic variables such as stroke volume, cardiac output and systemic vascular resistance, and cerebral haemodynamic and metabolic variables. However, for any monitoring device to become ‘standard’ it must not only be reliable and improve safety, but must also lead to better patient care, clinical outcome
Ó The Board of Management and Trustees of the British Journal of Anaesthesia 2006. All rights reserved. For Permissions, please e-mail: [email protected]
Downloaded from http://bja.oxfordjournals.org/ at Lakehead University on March 18, 2015
Monitoring, to health care professionals and in particular anaesthetists, usually means the continuous measurement of patient variables over time. However, the word monitor derives from the Latin monere (to warn) and modern English dictionaries include almost a dozen different connotations. These range from an observational warning or recording device (or individual) to audiovisual terminology, a senior school pupil and types of lizard or warship. In a similar way, the term monitor in anaesthesia, critical care, pain management or perioperative medicine actually encompasses a variety of technologies that address diverse but overlapping aspects of anaesthesia and medical care. Over the past two decades, these technologies have advanced greatly and the availability of monitoring devices has multiplied exponentially. This has occurred in conjunction with the developments in electronics, computing, information technology and mobile communications, which has characterized the past 20 yr. This issue of the British Journal of Anaesthesia is based on the symposium held in March 2006 and organized jointly by The Royal College of Anaesthetists and British Journal of Anaesthesia. The articles range from the interaction between humans and machines, new and emerging technologies and their application not only inside and outside the operating room but also at the extremes of environments where medical care may be needed. In order to fully understand the panoply of modern monitoring, we should remember the progress made in the very recent past. When exactly instrumental monitoring started in anaesthetic practice is unclear, but the core guiding principle of the profession of anaesthesia has always been ‘For some must watch, while some must sleep’ (Hamlet, W. Shakespeare). ‘Vigilance’ has been the motto of the ASA since it was founded in 1905. While some of us can still remember the days up to the mid-1980s when this vigilance, in practical terms, was restricted to an anaesthetist’s utilization of senses by inspection or palpation for clinical signs (observation of the patient’s colour with a finger on the pulse), there has been convincing evidence that our human senses by themselves, are not reliable in keeping ‘eternal
Editorial
the monitoring devices of the future will no longer be confined to machines which simply warn the clinician or record clinical events. They will be capable of controlling clinical care in a variety of forms by engendering action by the clinician or by initiating an action on their own. New ventilators are already capable of monitoring lung mechanics and automatically adjusting the ventilator settings to prevent ventilator associated lung injury or to aid weaning.19 The integration of a pharmacokinetic-based anaesthetic infusion pump with a depth of anaesthesia monitor to determine individual dose–response curves to the anaesthetic which could feed back to the pump and tailor the anaesthetic accordingly, is not far away.12 Similar systems could also control the administration of fluids or vasoactive drugs in critical care according to patient’s cardiovascular data and guided by protocols set by the clinician. An integrated cardiovascular monitor might incorporate the data from existing monitors on a patient’s cardiac rhythm, contractility, cardiac output, oxygen flux and organ or tissue perfusion to guide therapy, and some of the currently available monitors are close to this capability. These types of monitor would enable patient monitoring and automated correction of physiological abnormalities to occur together, freeing the clinician to concentrate on diagnosis and other aspects of therapy. If validated, these types of monitors could decrease the element of human error, which underlies many medical mishaps or critical incidents. However, technology is not perfect, and most clinicians are aware of the limitations of protocol-driven medicine. Humans are infinitely variable in their responses to disease and medical interventions and will technology be able to reliably account for this? Medicine is full of uncertainties and no monitor will always be 100% accurate and reliable. How many of us have been in a situation when the monitor tells us something is wrong but our instincts tell us otherwise? Would an over-reliance on new technology diminish our clinical acumen or instinct over time? What if the ‘smart’ monitor integrated with the anaesthesia or critical care management system acted to produce patient harm? Who would be responsible—the machine, the manufacturer or the clinician? Despite our clinical frailties, patients rightly expect their doctors to be human as well as humane, and may be uncomfortable if therapy was being directed by a machine. Finally, new technology is only better if patients’ outcome is improved. We clinicians must be aware of developments and be in a position to direct them—we should continue to monitor the monitors. J. P. Thompson1* R. P. Mahajan2 1
University Department of Cardiovascular Sciences Division of Anaesthesia Critical Care and Pain Management Leicester Royal Infirmary
2
Downloaded from http://bja.oxfordjournals.org/ at Lakehead University on March 18, 2015
and be cost-effective. Furthermore, the monitoring device should ideally integrate with the ‘standard’ monitoring and management plan. For example, in this issue Bruhn and colleagues12 review the role of depth of anaesthesia monitoring in avoiding both awareness and excessive depth of anaesthesia to thus improve outcome in patients undergoing anaesthesia or monitored sedation. They correctly suggest that for these to become part of standard care, awareness should be included in outcome measures. Any cost–benefit analysis should include the possible savings on drug usage, recovery times, complications of ‘deep’ anaesthesia and hospital stay. This attitude to the introduction of monitoring is not universal. For example, measurement of intracranial pressure (ICP) is considered an essential part of monitoring for neurosurgical and neurological patients, despite a lack of grade 1 evidence that ICP measurement or estimation of cerebral blood flow has any impact on outcome after acute brain injury.13 New technologies including on-line cerebral microdialysis14 and novel imaging modalities are being actively investigated and, although they have considerable potential, their role is not yet established. Another approach is to combine information from new and existing technologies to produce multimodal monitoring. There is some evidence that outcome after head injury is improved if treatment is guided by ICP monitoring in combination with measurements of brain oxygen tension.15 Monitoring has changed our practice in other ways. Kneeshaw16 argues that transoesophageal echocardiography has significantly changed the role of anaesthetists experienced in its use to become indispensable in the diagnosis and management of circulatory insufficiency in the operating room and ICU. Intraoperative echocardiography is more than a monitor, as surgeons increasingly rely on the information it provides to direct their surgical procedure. This situation has arisen as a result of the development of a specific training and accreditation programme which is unique amongst monitoring modalities. Whereas a number of recent studies have linked some aspects of monitoring with improved outcomes, the limitations of monitoring have also become apparent. Young and Griffiths17 correctly observe that more information is not always better and monitoring will only benefit the patient if there is an effective treatment for the underlying cause. The right information must be collected at the right time, interpreted correctly and acted upon appropriately. One way to overcome these delays is to combine the information from several patients or systems. Tarassenko and colleagues18 review the role of integrated monitoring systems in a ward setting in picking up early warning signs and acting on them quickly. Despite the apparent failure in studies of some monitoring devices to produce clear clinical benefits, we should not be deterred, as the availability of improved monitoring techniques can potentially lead to dramatic changes in clinical practice. The reviews in this educational issue indicate that
Editorial
Leicester, UK 2 University Hospitals NHS Trust Queen’s Medical Centre Nottingham, UK *E-mail: [email protected]
10
11
References 12
13 14 15
16 17
18
19
3
Downloaded from http://bja.oxfordjournals.org/ at Lakehead University on March 18, 2015
1 Comroe JH, Bothelo S. The unreliability of cyanosis in the recognition of arterial anoxemia. Am J Med Sci 1947; 214: 1–2 2 Weingarten M. Anaesthetic and ventilator mishaps: prevention and direction. Crit Care Med 1986; 14: 1084–6 3 Semmes BJ, Tobin MJ, Snyder JV, Grenvik A. Subjective and objective measurement of tidal volume in critically ill patients. Chest 1985; 87: 577–9 4 Eichhorn JH, Cooper JB, Cullen DJ, Maier WR, Philip JH, Seeman RG. Standards of patient monitoring during anaesthesia at Harward Medical School. JAMA 1986; 256: 1017–20 5 Recommendations for Standards of Monitoring during Anaesthesia and Recovery. Association of Anaesthetists of Great Britain and Ireland, 2000 6 Keenan RL, Boyan CP. Decreasing frequency of anaesthetic cardiac arrests. J Clin Anesth 1991; 3: 354–7 7 Webb RK, van der Walt JH, Runciman WB, et al. Which monitor? An analysis of 2000 incident reports. Anaesth Intensive Care 1993; 21: 529–42 8 McKay WP, Noble WH. Critical incidents detected by pulse oximetry during anaesthesia. Can J Anaesth 1988; 35: 265–9 9 Cullen DJ, Nemaskal JR, Cooper JB, Zaslavsky A, Dwyer MJ. Effect of pulse oximetry, age and ASA physical status on the frequency
of patients admitted unexpectedly to a post-operative intensive care unit. Anesth Analg 1992; 74: 181–8 Moller JT, Johannessen NW, Espersen K, et al. Randomized evaluation of pulse oximetry in 20,802 patients. II. Perioperative events and postoperative complications. Anesthesiology 1993; 78: 444–53 Blitt CD. History and philosophy of monitoring. In: Lake CL, Hines RL, Blitt CD, eds. Clinical Monitoring: Practical Applications for Anaesthesia and Critical Care. New York: WB Saunders Company, 2001 Bruhn J, Myles PS, Sneyd JR, Struys MMRF. Depth of anaesthesia monitoring: what’s available, what’s validated and what’s next. Br J Anaesth 2006; 97: 85–94 Steiner LA, Andrews PJD. Monitoring the injured brain: ICP and CBF. Br J Anaesth 2006; 97: 26–38 Tisdall MM, Smith M. Cerebral microdialysis: research technique or clinical tool. Br J Anaesth 2006; 97: 18–25 Stiefel MF, Spiotta A, Gracias VH, et al. Reduced mortality rate in patients with severe traumatic brain injury treated with brain tissue oxygen monitoring. J Neurosurg 2005; 103: 805–11 Kneeshaw JD. Transoesophageal echocardiography (TOE) in the operating room. Br J Anaesth 2006; 97: 77–84 Young D, Griffiths J. Clinical trials of monitoring in anaesthesia, critical care and acute ward care: a review. Br J Anaesth 2006; 97: 39–45 Tarassenko L, Hann A, Young D. Integrated monitoring and analysis for early warning of patient deterioration. Br J Anaesth 2006; 97: 64–8 Macnaughton PD. New ventilators for the ICU: usefulness of lung performance reporting. Br J Anaesth 2006; 97: 57–63