A monitor would have saved my child’s life. All that stands between us and universal postoperative monitoring, is the will to require it.
–Lenore Alexander 1
In this issue of Anesthesia & Analgesia, Sun et al.2 address a critically important patient safety question that has been a Anesthesia Patient Safety Foundation (APSF) safety initiative since 2006.3–5 On the basis of data using continuous pulse oximetry in patients following noncardiac surgery, Sun et al. found that arterial hypoxemia was “common and prolonged whereas oxygen saturation values recorded in medical records seriously underestimated the severity of postoperative arterial hypoxemia.”
Unrecognized arterial hypoxemia in the postoperative period as described by Sun et al. and others has added clinical significance when one considers the fact that “failure to rescue” and postoperative respiratory failure are the first and third most common patient safety–related adverse events affecting the Medicare population in US hospitals.6 Indeed, “failure to rescue” is more accurately depicted as “failure to recognize.” The resuscitation literature suggests that the most common antecedent vital sign abnormality to a cardiopulmonary arrest is respiratory in nature, and the poorest outcomes often occur on the general care floor and in patients with significant preexisting morbidity.6
Parallel to the Sun et al.’s2 data are APSF’s recommendation that all hospitalized adult patients receiving opioids for postoperative pain management should be monitored with continuous pulse oximetry, with data transmitted wirelessly to a qualified health care professional.5 APSF also recommends incorporation of a monitor of ventilation if supplemental oxygen is needed to maintain an acceptable SpO2.
APSF’s recommendation for “electronic monitoring of all hospitalized adult patients receiving postoperative opioids for pain management” reflects an evolution of the pros and cons of routine pulse oximetry monitoring spanning nearly a decade, with the initial APSF report appearing in the 2006 APSF Newsletter.3 Prominent considerations during this evolution included (1) the belief that such a recommendation would be more robust if it was evidence-based, (2) the predictable resistance to monitoring all patients when only a rare patient is perceived to be at risk, and (3) added cost of the universal introduction of the necessary technology. During this evolutionary period, other organizations (The Joint Commission, Center for Medicare and Medicaid Services, Association for the Advancement of Medical Instrumentation) have also recognized the importance of routine electronic monitoring for patient safety in the postoperative period.7–9
The issue of evidence-based medicine to support changes in patient care has been addressed by Leape et al.10 These authors emphasize that monitors that improve patient safety may not be supported by evidence-based data and, in fact, insistence on such data for institution of patient safety practices may be counterproductive. Evidence from randomized controlled trials is important information, but it is not necessary for acceptance of a safety practice. For policy makers to wait for incontrovertible proof of effectiveness before recommending a safety practice can become a prescription for inaction. Indeed, pulse oximetry did not become a standard of care because of proof that it reduced adverse outcomes but rather because it exhibited compelling theoretical benefit without harm.11
In response to concerns about the safety of patient-controlled analgesia (PCA) in the postoperative period, APSF held an expert’s conference on October 13, 2006, that was attended by >100 clinicians, scientists, and medical industry representatives. At this conference, it was recognized that available evidence suggested a significant and underappreciated risk of serious injury from PCA and neuraxial opioids postoperatively. Although some patient populations (notably those patients with obstructive sleep apnea) appeared to be at a higher risk, there was still a low but poorly predictable incidence of life-threatening opioid-induced ventilatory impairment (OIVI) in young healthy patients. On the basis of the findings of this conference, APSF recommended the routine use of continuous postoperative respiratory monitoring (pulse oximetry) in at-risk patients receiving PCA or neuraxial opioids.3 In addition, when supplemental oxygen was indicated, monitoring of ventilation may warrant the use of technology designed to access breathing or to estimate arterial carbon dioxide concentrations, based on the recognition that pulse oximetry has reduced sensitivity as a monitor of hypoventilation when supplemental oxygen is administered.3
An editorial in the Summer 2009 APSF Newsletter addressed the continuing problem of OIVI.4 Respiratory monitoring often continued to rely on the nurse’s periodic observation and documentation of respiratory rate. Even when continuous pulse oximetry was used, supplemental oxygen was often being administered without appreciating its potential to mask progressive hypoventilation. Going beyond the 2006 APSF conference recommendations, the editorial’s authors now recommended that “continuous monitoring of oxygenation (pulse oximetry) become the routine rather than the exception.” Furthermore, confirming the “need for supplemental oxygen” was emphasized, especially if pulse oximetry and/or intermittent nursing assessment were the only methods for identifying progressive hypoventilation.
To further the June 2009 editorial’s recommendations, APSF sponsored a second expert’s conference in June 2011 entitled, Essential Monitoring Strategies to Detect Clinically Significant Drug-Induced Respiratory Depression in the Postoperative Period.4,5,12 The attendees reaffirmed the earlier APSF recommendations that continuous electronic monitoring should be used for all adult patients in a health care facility who are receiving parenteral opioids for postoperative pain management. Furthermore, monitors of ventilation should be used when supplemental oxygen is needed to maintain an acceptable arterial oxygen concentration. Improved education of health care providers on the dangers of postoperative opioids and better assessment of sedation level were viewed as critical steps in the prevention of OIVI. It was acknowledged that limited resources might result in staged implementation of continuous monitoring strategies with the highest risk groups being monitored first, but with the goal of continuous monitoring of all adult patients receiving postoperative opioids. Risk stratification was considered unacceptable, because it is not possible to always identify the patient at risk.
In support of APSF’s recommendations for continuous electronic monitoring, there is evidence in the peer-reviewed literature that routine continuous pulse oximetry monitoring reduces the likelihood of adverse events.13,14 For example, Taenzer et al.13 implemented a patient surveillance system (PSS) in the postoperative care setting that used continuous pulse oximetry to facilitate early recognition of the need for rescue interventions. The PSS alerted the patient’s nurse via a pager when preset physiologic parameter alarm systems were violated. By setting alarm limits to minimize false positives (set to alarm when the SpO2 was <80% and the heart rate was <50 beats/min or >140 beats/min), the PSS maximized patient and nurse acceptance and only alerted for clinically meaningful situations (actionable events). In this report, early detection of deteriorations of physiologic parameters (SpO2 and heart rate) led to fewer rescue events and a decreased need to escalate care (transfer to a critical care unit).13
The “pushback” to accepting continuous electronic monitoring is the cost of instituting this technology for the care of patients who currently are managed in the postoperative period exclusively with nursing vigilance. Taenzer and Blike15 addressed the question of “return on investment” when considering the cost of instituting routine continuous electronic monitoring. The cost-effectiveness depends on both the incidence of adverse events in the patient population and the success of the PSS in reducing intensive care unit (ICU) transfers and days spent in the ICU. Other cost savings opportunities could include medicolegal expenses or reduced utilization of rapid response systems. It is reasonable to conclude that the cost of instituting and maintaining the technology necessary for continuous electronic monitoring would be more than offset by cost savings from reduced adverse events and care in the ICU.
All that stands between us and universal postoperative monitoring, is the will to require it.
–Lenore Alexander 1
Name: Robert K. Stoelting, MD.
Contribution: This author wrote the manuscript.
Attestation: Robert K. Stoelting approved the final manuscript.
This manuscript was handled by: Sorin J. Brull, MD, FCARCSI (Hon).
2. Sun Z, Sessler DI, Dalton JE, Devereaux PJ, Shahinyan A, Naylor AJ, Hutcherson MT, Finnegan PS, Tandon V, Darvish-Kazem S, Chugh S, Alzayer H, Kurz A. Postoperative hypoxemia is common and persistent: a prospective blinded observational study. Anesth Analg. 2015;121:709–15
5. Weinger MB. No patient shall be harmed by opioid-induced respiratory depression: proceedings of essential monitoring strategies to detect clinically significant drug-induced respiratory depression in the postoperative period. APSF Newsletter. 2011;26:21–6 Available at: http://www.apsf.org/newsletters/pdf/fall_2011.pdf
6. Overdyk FJ. Postoperative opioids remain a serious patient safety threat. Anesthesiology. 2010;113:259–60
9. National Coalition to Promote Continuous Monitoring of Patients on Opioids Draft Consensus Statement. AAMI Foundation Healthcare Technology Safety Institute. November 14, 2014 Chicago, IL Available at: http://www.aami.org/htsi/opioids/index.html
10. Leape LL, Berwick DM, Bates DW. What practices will most improve safety? Evidence-based medicine meets patient safety. JAMA. 2002;288:501–7
11. Green SM, Pershad J. Should capnographic monitoring be standard practice during emergency department procedural sedation and analgesia? Pro and con. Ann Emerg Med. 2010;55:265–7
12. Executive Summary (7 minute video): Opioid-induced ventilatory impairment (OIVI): time for a change in the monitoring strategy for postoperative PCA patients. Available at: http://www.apsf.org/resources/oivi/
13. Taenzer AH, Pyke JB, McGrath SP, Blike GT. Impact of pulse oximetry surveillance on rescue events and intensive care unit transfers: a before-and-after concurrence study. Anesthesiology. 2010;112:282–7
14. Taenzer A. A comparison of oxygen saturation data in inpatients with low oxygen saturation using automated continuous monitoring and intermittent data charting. Anesth Analg. 2014;118:326–31