Patient safety is a priority for any healthcare provider or institution. And patient surveillance is a key component of patient safety.1 However, to quote Saab et al.,2 ‘hospitals continue to use a system for monitoring ward patients that was designed a century ago and never adapted to the much higher frailty and severity that is now typical amongst hospitalised patients, and that fails to take advantage of available continuous monitoring technology’.
Why re-invent patient surveillance on the wards
There are multiple reasons to improve the way we monitor patients on hospital wards (Fig. 1). First, ward nurses are responsible for a greater number of patients than in intensive care units (ICU) or postanaesthesia care units. Therefore, vital sign spot-checks are not always done on time and may be incomplete.3 For instance, respiratory rate is frequently missing or simply guesstimated to be around 16 breaths per minute in the absence of overt difficulties in breathing. In this respect, ‘failure to rescue’, which is defined as postoperative death related to any potentially treatable complication, has been shown to be inversely proportional to the nurse-patient ratio.4
Vital signs spot-checks may be delayed but, even when done at the assigned times, a nurse spending 10 min with a patient every 4 h, would leave them without any surveillance 96% of the time. A recent study2 of postoperative patients showed that around 80% of hypoxaemic and hypotensive events are missed by nurses spot-checking oxygen saturation and blood pressure every 4 h. This is regrettable as most in-hospital cardiac arrests and severe adverse events requiring ICU admission are preceded by progressive clinical deterioration that could be detected earlier if vital signs were monitored more closely and if monitoring systems were alerting clinicians to trends and trajectories, and not only when arbitrary limits have been crossed.
In addition, the frailty and severity of comorbidities of ward patients has increased progressively over time and most in-hospital cardiac arrests occur today on general care floors.5 If anaesthesia-related deaths have become exceptions, postoperative complications and deaths remain far too common.6 It is estimated that around 17% of patients undergoing nonambulatory surgery develop at least one postoperative complication and that between 1 and 2%, ultimately die within 30 days following the procedure. Given the global volume of surgery, this represents over four million postoperative deaths worldwide every year, that is, more than the number of deaths related to malaria, tuberculosis and HIV combined.7
Another potential challenge hospitals may have to face is the lack of high-dependency beds to closely monitor the sickest patients. The number of ICU bed per capita is highly variable from one country to the other but the current COVID-19 pandemic revealed that maximum ICU capacities were reached quickly in many regions. Millions of cases of elective surgery had to be postponed to free up ICU beds for critically ill COVID-19 patients. In addition, because of ICU bed shortages, many COVID-19 patients had to receive high-flow oxygen, or even noninvasive ventilation, in non-ICU departments. This situation – far from optimal from a patient safety perspective – highlights the need to increase the number of ICU beds and to upgrade monitoring strategies in general care wards.8
The rise of digital monitoring solutions
Technological and digital innovations have transformed monitoring tools in a short period of time. It is today possible to record a nine-lead ECG with a smartwatch, to perform an echography with a smartphone and to buy a wireless medical grade pulse oximeter from an online store at a reasonable price.9 Tomorrow, smart rings will continuously monitor blood pressure, smartwatches will noninvasively estimate blood glucose and smart headbands will constantly check the level of vigilance of truck drivers and airplane pilots.
On hospital wards, several clinical studies have already shown that continuous monitoring of vital signs may decrease the number of rapid response team interventions, ICU admissions, cardiac arrests and deaths.3 However, most have been done with fixed bedside pulse oximeters or capnographic sensors, which is not the panacea if one considers that these systems force patients to stay in bed and that nasal prongs for capnography are often poorly tolerated and dislodged. New monitoring solutions have been cleared for medical use over the last few years.10,11 They include piezo electric sensors, either as part of high-end hospital beds or of plastic pads which are left under the mattress, to monitor heart rate and respiratory rate, video-monitoring systems to monitor heart rate from subtle changes in skin colour and respiratory rate from chest or abdomen movements, bioimpedance necklaces to monitor heart rate, respiratory rate and thoracic fluid content in ambulatory patients, adhesive patches containing electrodes, accelerometers, thermistors or/and piezo electric sensors to monitor heart rate, respiratory rate and skin temperature. Blood pressure changes can be detected continuously in patients wearing electrodes and a pulse oximeter from the pulse wave transit time (or pulse arrival time) method.12 The new pulse decomposition technique enables the continuous recording of a blood pressure waveform wirelessly from a low-pressure finger cuff. In the future, machine learning algorithms have the potential to extract blood pressure information from pulse oximetry waveforms and the miniaturisation of volume clamp methods may enable continuous blood pressure monitoring from a finger ring.12
Among all these techniques, specifically designed for continuous monitoring of vital signs on hospital wards, wireless wearables are progressively emerging as the ideal solution, mainly as they are comfortable to wear, and they allow patients freedom of movement, away from their bed.3
Real-life implementation: a stepwise approach
Although now technically feasible, continuous monitoring of vital signs on ward and ambulatory patients is a dramatic change in clinical practice that cannot be adopted immediately. Sticking an electronic adhesive patch to the patient's skin is not going to solve any problems if the physiological information recorded is not accurate or it is not acted upon appropriately.
First, it is our responsibility as clinicians to ensure that monitoring solutions coming to market are accurate and precise enough to detect clinical deterioration. Despite the myriad of solutions and sensors now available, very few have been validated by well designed independent clinical studies and tested in an intended-use context.13
Second, once a monitoring system has been selected, it is crucial to ensure its implementation is not going to result in a significant increase in false alarms and nurse workload.14 To do so, smart algorithms may be needed to filter artifacts,15 cross-check physiological signals, and aggregate the information, ideally into a single deterioration index that can be a number or simply a colour (green → red) or even a smiley . Alarm settings should be individualised, keeping in mind that patients often have different baseline conditions and hence that what is normal for one (e.g. a heart rate at 45 beats per minute for a patient receiving beta-blockers, or a SpO2 at 92% for a patient with chronic obstructive pulmonary disease) may reveal clinical deterioration for another.16 Increasing the time between the detection of an abnormal signal and the alarm (i.e. the annunciation delay) may also help to reduce false alarms related to transient technical failures or movement artifacts. Connectivity should be robust enough to prevent prolonged disruptions that could generate false alerts as well.17 Importantly, to enhance patient satisfaction and prevent sleep disorders, alarms should be banned from hospital rooms and received by caregivers at a central station, on their pager or smartphone, or in a dedicated command center.3
Finally, processes must be put in place to ensure that the detection of clinical deterioration is followed by a quick and appropriate response. Indeed, if the lack of an effective ‘afferent limb’ has been advocated to explain disappointing results after the implementation of rapid response systems,18 the lack of ‘efferent limb’ would likely be responsible for the same disappointment if using smart monitoring systems alone. These processes should be tailored to clinician habits and hospital organisation but, in any case, must clearly define who should be informed (the nurse, the ward physician or the rapid response team) and what should be done.14
On hospital wards, because of the low nurse–patient ratio and the intermittent nature of vital sign spot-checks, there is increasing evidence that clinical deterioration may be overlooked for hours. Multiple monitoring systems have recently been developed to monitor vital signs automatically and continuously. They may help to detect clinical deterioration earlier, decrease the number of rapid response team interventions, ICU admissions, cardiac arrests and deaths. From a sensor standpoint, wireless wearables are emerging as the ideal solution for monitoring on the wards as they are patient friendly and they allow early mobilisation, which is a key element of enhanced recovery programs. Clinical studies are needed to clarify the best strategies to respond effectively to early deterioration alerts, and what is the impact on nurse and physician workload. Future trials will also have to investigate what is the impact on key outcomes, such as ICU admission and hospital length of stay, and which patients may benefit the most from such monitoring innovations. Whether wireless wearables could also be used for home monitoring, either before surgery (to better individualise perioperative management) or after hospital discharge (to detect late complications) should also be an active field of research within the next 5 to 10 years.
Acknowledgements relating to this article
Assistance with the editorial: none.
Financial support and sponsorship: none.
Conflicts of interest: FM is the founder and managing director of MiCo, a Swiss consulting and research firm. MiCo does not sell any medical product and FM does not own shares nor receive royalties from any medical device company.
Comment from the editor: this article was checked and accepted by the Editors, but was not sent for external peer-review.
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