When patients having major surgery reach the post-anaesthesia care unit, families naturally assume that they have survived the most dangerous part of the perioperative experience. Their assumption is wrong. Mortality in the 30 days after surgery is 140 times higher than intraoperative mortality.[1,2] In fact, if the month after surgery were considered a disease, it would be the world’s third leading cause of death.[3]

The most common causes of 30-day postoperative mortality are major bleeding and cardiopulmonary complications.[4–6] Myocardial injury is strongly related to both intraoperative and postoperative hypotension. Ward hypotension, hypertension, and hypoxemia are common, profound, and prolonged—and mostly missed by conventional vital sign monitoring at four-hours intervals.[7] Frighteningly, half or more of these events are missed by routine 4-hour nursing checks.[8,9]

Ward monitoring has hardly changed over last half-century, although there have been major changes in hospital populations. Substantive changes include: (1) ambulatory surgery is routine for relatively healthy patients, with most surgery in the United States done on an out-patient basis; (2) it is now common to perform large operations in elderly and frail patients; and (3) even when patients are admitted after surgery, the duration of hospitalization is usually short. Ward patients are therefore much sicker now than previously.

Vital signs usually deteriorate 6–12 hours before cardiac and respiratory arrests occur.[10–12] About 60% of critical events such as death and unplanned intensive care unit (ICU) admission are preceded by clear abnormalities.[13] Furthermore, continuous monitoring is generally well accepted by patients and nurses.[14] Patients would be better served if we could detect deterioration early and therefore prevent critical episodes, rather than wait for crises and then try to rescue patients.

Clinically important perturbations can be detected by continuous ward monitoring which is now readily available. There are already battery-powered, untethered ward systems that continuously monitor a combination of physiologic variables, such as blood pressure, electrocardiogram, heart rate, oxygen saturation, respiratory rate, body position, activity, and location.[15,16] In other words, we need to get past “failure to rescue”, a concept dating to 1992,[17] and use available continuous monitors to prevent critical events rather than trying to save patients thereafter.[18]

Continuous ward hemodynamic and respiratory disturbances monitoring can detect potentially serious events that are otherwise missed by routine intermittent vital sign monitoring. There nonetheless remain challenges related to continuous ward monitoring. Issues that require additional attention include appropriate patient selection, device acceptability by patients and nurses, device connectivity and battery duration, validation of new devices, data integration and synthesis, balance between alarm fatigue and missed events, patient-specific threshold for alarms, appropriate analysis strategies for machine learning or artificial intelligence, directed front-line nurse response, economic evaluation, and payment models.

Much additional research is needed. New devices will require validation to confirm measurement accuracy, reliable connectivity, along with patient and clinician acceptability. Both patients and medical staff will need to adjust to wireless monitoring devices. Risk-stratification tools may be needed to select patients who are likely to benefit the most from continuous monitoring and hence to rationalize the implementation—although our assumption is that all inpatients should eventually be continuously monitored. Furthermore, appropriate machine learning or artificial intelligence analysis strategies and individualized warning threshold should be developed to balance alarm fatigue with delayed event recognition. Finally, large-scale pragmatic trials should evaluate the clinical benefit, medical workload, and cost-effectiveness of continuous ward monitoring on activation of rapid response teams, ICU-admissions, and duration of hospitalization.

Meanwhile we also lack another factor, which is detailed medical care of postoperative patients. Too many fragile postoperative patients receive little more than a few minutes of surgical care early in the morning before surgeons go to operating rooms for their days’ work. That might have been sufficient a half-century ago when patients were admitted days before surgery and stayed for weeks afterwards. Furthermore, most operations in that era were relatively small, patients were usually <60 years old, and few had major comorbidities. But that certainly is not our current situation where relatively healthy patients are not even admitted, half our patients are more than 60 years old, and we routinely do major operations on patients who have serious comorbidities. Consequently, the average acuity of patients on surgical wards is far higher than previously — but we still monitor and manage them much as we did 50 years ago.

Much ward mortality is preventable. But preventing deaths after surgery will require a new approach. Specifically, we need to combine continuous ward monitoring with elaborate medical management of postoperative patients. In practice, that means a collaboration amongst anesthesiologist, hospitalists, internal medicine physicians, and nursing to provide intense management of postoperative patients, including management of underlying conditions. Research will also be required to identify the most effective ways to use continuous monitoring data. For example, artificial intelligence will presumably help interpret dense streams of messy data that continuous monitoring generates. Continuous ward monitoring is an opportunity we should take — because by doing so we can save tens-of-thousands of lives each year.

Conflicts of interest

Dr. Sessler’s department has been supported by Edwards Lifesciences (Irvine, CA), GE Healthcare (Chicago, IL), Masimo (Irvine, CA), and Sotera Wireless (San Diego, CA).

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