Remote vision-based digital patient monitoring of pulse and respiratory rates in acute medical wards

Correspondence to Dr Adam Lewis, Department of Health Sciences, Brunel University London, London, UK; [email protected]

Introduction

Regular measurement of vital signs in patients on acute wards detects or predicts clinical deterioration.¹ Typically, nurses measure PR with a finger oximeter, and RR by counting breaths, usually over 15 or 30 s. Recently Vision-Based Patient Monitoring (VBPM) has made these measurements possible by remote digital technology without nurse interaction. This technique has been validated in the ICU² and a dialysis unit³ and is used in mental health settings following clearance as a medical device.⁴ Here we evaluated VBPM in an acute medical setting.

Methods

Routine measurements by nurses (including trained clinical support members of the nursing team) were not altered in any way for this study. They followed ward protocols and the data were taken from the patients’ medical records.

The VBPM software used was Oxevision (Oxehealth Ltd, Oxford, UK). This uses a wall-mounted digital camera with infra-red illuminators allowing measurement even in complete darkness. Computer analysis tracks small movements of the chest to give RR and reflectance photoplethysmography detects changes in transmitted light in the skin with each heartbeat to measure PR.

VBPM was set up in two single rooms on two adult respiratory wards at the Royal Brompton Hospital, London (RBH) and four single rooms on a surgical orthopaedic ward at the John Radcliffe Hospital, Oxford (JRH) with ethics committee approval (Social Care Research Ethics Committee no 17/IEC08/0026 and the East of England – Essex Research Ethics Committee no 18/EE/0221 respectively). Patients gave written informed consent. They were admitted at RBH for treatment of acute respiratory conditions and at JRH for fractures and other acute orthopaedic conditions.

The VBPM system could be temporarily switched off by nurses but otherwise ran continuously. However, VBPM was not analysed when a nurse was in the room as it cannot reliably differentiate between two people’s vital signs. Therefore, VBPM measurements were paired with nurse recordings when they were recorded within 5 min of each other and the paired data analysed. VBPM was not available for patient management during the course of the study and nurses were blinded to its output.

To validate the VBPM RR measurements, a reviewer was shown video clips of patients breathing....