Respiratory Rates - Accuracy of Contact-free Monitoring of Respiratory Rates

Respiratory Rates - Accuracy of Contact-free Monitoring of Respiratory Rates in the Triage Setting of an Emergency Department

Respiratory rate is an important predictor for many clinical outcomes in Emergency Medicine. Nevertheless it's measurement is often omitted as it is time-consuming and cumbersome. It is the only vital sign that is not routinely assessed by a device. In a pilot study was showed that a camera based monitoring system measures reliably respiratory rates in healthy volunteers.

The goal of this study is to test the accuracy of the same system in real patients in the triage setting of an Emergency Department (ED).

For triage of emergency patients at the Emergency Department of the University Hospital Basel the emergency severity index (ESI) is used. At decision point "D" in the ESI-algorithm vital signs such as respiratory rate, heart rate and oxygen saturation are needed.

According to the guidelines the respiratory rate is visually counted for one minute (WHOrecommendation) by a triage nurse.

Simultaneously in addition to the visual counting, it is planned to measure the same vital sign as part of our study also through a camera-based prototype application (CBPA) and capnography as a gold standard.

Hence the triage process is not prolongated through our study, only completed and a guideline compliant procedure is ensured which is only performed in a relatively low percentage in the ED of the University Hospital Basel. Clinical decisions are exclusively based on the actual clinical standard of visual counting and are not influenced by the measurements of our study.

For the capnography, which were considered as the most accurate method, the patient wears a nasal sample line (Philips® Heartstart MRx mit Philips® Smart CapnoLine™PlusO2Long Oral/Nasal Sample Line).

The CBPA system consists of a notebook (HP Zbook 15 G3, S/N: CND705IXT6), USB-camera with lens (Tamron CCTV lens, CE 4402789484; UI3060 camera, 20170329-E347840), USB-harddrive (Western digital R/N D8B, S/N: WXA1E661J0XJ) to save the signals and an implement camera-based algorithm for extraction of breathing signals. The camera is pointing towards the torso of the patient to display it on the screen in a real-time application. The software is able to detect the respiratory-specific chest movements and generates a respiratory wave on the computer. From the configuration and frequency of these respiratory waves the software calculates the respiratory rate. No videos are recorded.

The data is acquired in a standardised protocol and stored coded in an Access®-database. To prevent potential bias the vital signs will be written down in the following order: 1. RR by visual counting 2. RR by CBPA 3. RR by capnography. The measurements take place in rooms of the ED which are designated to triage emergency patients.

As possible confounders sex, age and BMI are registered.

Inclusion Criteria:

• All walk-in patients older than 18 with a presumed ESI score of 2-3 presenting to the ED of the University Hospital of Basel will be eligible for inclusion.

Exclusion Criteria:

• Excluded will be (1) patients brought in by ambulance or helicopter, (2) unstable patients needing immediate medical treatment, (3) confused, restless, deaf patients having difficulty to follow the study instructions (4) Clear signs of refusal to participate the study.