Assessment of the feasibility of an ultra-low power, wireless digital patch for the continuous ambulatory monitoring of vital signs

Abstract

Background and objectivesVital signs are usually recorded at 4–8 h intervals in hospital patients, and deterioration between measurements can have serious consequences. The primary study objective was to assess agreement between a new ultra-low power, wireless and wearable surveillance system for continuous ambulatory monitoring of vital signs and a widely used clinical vital signs monitor. The secondary objective was to examine the system's ability to automatically identify and reject invalid physiological data.SettingSingle hospital centre.ParticipantsHeart and respiratory rate were recorded over 2 h in 20 patients undergoing elective surgery and a second group of 41 patients with comorbid conditions, in the general ward.Outcome measuresPrimary outcome measures were limits of agreement and bias. The secondary outcome measure was proportion of data rejected.ResultsThe digital patch provided reliable heart rate values in the majority of patients (about 80%) with normal sinus rhythm, and in the presence of abnormal ECG recordings (excluding aperiodic arrhythmias such as atrial fibrillation). The mean difference between systems was less than ±1 bpm in all patient groups studied. Although respiratory data were more frequently rejected as invalid because of the high sensitivity of impedance pneumography to motion artefacts, valid rates were reported for 50% of recordings with a mean difference of less than ±1 brpm compared with the bedside monitor. Correlation between systems was statistically significant (p<0.0001) for heart and respiratory rate, apart from respiratory rate in patients with atrial fibrillation (p=0.02).ConclusionsOverall agreement between digital patch and clinical monitor was satisfactory, as was the efficacy of the system for automatic rejection of invalid data. Wireless monitoring technologies, such as the one tested, may offer clinical value when implemented as part of wider hospital systems that integrate and support existing clinical protocols and workflows.

Determination of saturation, heart rate, and respiratory rate at forearm using a Nellcor™ forehead SpO2-saturation sensor

“…Only a limited selection of currently available devices are capable of wirelessly monitoring vital signs [35,36], and none can collect all commonly monitored clinical signs from a single site. Here we report that, compared to recordings from a finger sensor, SpO 2 measurement at the wrist showed a poor correlation and a high RMSE.…”

Respiratory rates measured by a standardised clinical approach, ward staff, and a wireless device

“…After enrolment, participants were equipped with a SensiumVitals wireless, electronic patch (Sensium Healthcare Ltd., London, UK) using two ECG electrodes (Ambu BlueSensor VL, Ambu, Copenhagen, Denmark) and standard medical‐grade tape. This small, single‐use, commercially available device measures respiratory rate (using impedance pneumography), heart rate, and axillary temperature every 2 min . Measurements were wirelessly transferred to receivers temporarily installed in the ward and data were subsequently extracted from the database.…”

Novel wearable and contactless monitoring devices to identify deteriorating patients in the clinical setting: a systematic review protocol

“…Novel vital sign monitoring devices can be classified into either the wearable/contact or contactless space, with the former typically disposable sensors applied via adhesive [24], contained in a smaller device in direct contact with the body [25,26] or in near or direct proximity to the patient via mattress or bedsheet using ballistography [27] or electrical bioimpedence [28]. Contactless devices can be divided into image and nonimage based systems, with image-based systems typically employing RGB or infrared cameras, whereas non-image based systems have typically employed modalities including time of flight sensors [29,30], acoustics [31], and radar [32,33].…”