Triage is the first interaction between a patient and a nurse/paramedic. This assessment, usually performed at Emergency departments, is a highly dynamic process and there are international grading systems that according to the patient condition initiate the patient journey. Triage requires an initial rapid assessment followed by routine checks of the patients’ vitals, including respiratory rate, temperature, and pulse rate. Ideally, these checks should be performed continuously and remotely to reduce the workload on triage nurses; optimizing tools and monitoring systems can be introduced and include a wearable patient monitoring system that is not at the expense of the patient’s comfort and can be remotely monitored through wireless connectivity.
Triage nurses assess patients at the emergency department (ED); their role is primarily to determine the severity of each patient case. The word triage is derived from the French word “trier” as a battlefield sorting process implemented in 1792 by the surgeon in chief to Napoleon’s Imperial Guard, Baron Dominique Jean Larrey 
. Originally employed for sorting of mass casualties, this novel approach of evacuating the injured from the battlefield evolved throughout the conflicts of the 19th and 20th centuries into a sophisticated sorting process for immediate, urgent, and non-urgent cases. The assessment aligns with a sorting process and is based on three main patient conditions as the name indicates. These three main parameters are patient temperature, respiratory function, and cardiac function. Respiratory and cardiac functions are typically assessed together through auscultation of the body using traditional stethoscopes and a manual count estimating the length of respiratory cycle the heart rate in beats per minute. During the auscultation, a thermometer is fitted, body temperature is particularly important for pediatric COVID19 and geriatric patients.
Triage outcome is based on a standardized scale to differentiate non-life-threatening cases from critical cases. Assessment scales, such as The Australasian Triage Scale (ATS), present a five-point reference system to prioritise waiting time to treatment of each patient ranging from 0 (immediate) to 120 min 
. Modern triage typically has three stages, including prehospital triage where emergency vehicles are dispatched and prehospital resources are prepared; on site triage by the responding clinician; and thirdly, triage on ED arrival 
. Assessment should require less than 5 min to be conducted, so as not to delay other patients waiting. The high-pressure nature of the environment means most triage nurses are to conduct these rapid assessments considering clinical history, psychological assessment and discriminate between category urgencies making it inherently complex. In addition to the initial assessment, triage information must be continually updated to reflect the evolving patient’s condition and consequently update the ongoing responses. According to recent studies, presentation to ED is increasing globally, as example limited to Australia this number is currently estimated in over 22,000 patients per day 
. Due to increased financial limitations of the health system, resources are being stripped down 
leading to an increase demand on staff and, thus, led to the integration of telemedicine and wireless tools into the triage assessment 
. By definition Telemedicine is the employment of telecommunications and information technology for remote medical practices that include diagnosis, patient monitoring and data sharing to facilitate the collaboration in diagnosis and treatment of disease 
. Wearable monitoring systems play a key role within modern telemedicine approaches and have received significant attention in the implementation of modern triage assessment systems. Inclusion of these types of remote monitoring systems assist with standardizing and strengthening coordinated multidisciplinary medical approaches, particularly in mass casualty situations 
Established international triage systems based on scales, such as The Manchester Triage Scale (MTS), introduced in 1997, aims to reduce the subjectivity in assessment via the implementation of broader scale algorithms 
; or the similar 5-level triage algorithm “Emergency Severity Index” (ESI) introduced into the American ED’s in the late 1990’s 
; have been linked to poor sensitivity and specificity 
. By combining these well-established multileveled scales with integrated hardware technology and implemented within ED’s could greatly assist the flow and continued/continuous monitoring of patients in care; in other words, a wearable and wireless approach to triage assessment can enhance patient information collection, analysis and interpretation by improving information presentation and facilitating decision making processes 
Indispensable tool for triage is a stethoscope. Auscultation of bodily sounds makes easy to assess cardiac and respiratory rhythms; since their inception in 1816, stethoscopes have been an essential tool in medical assessments to perform mediate auscultation 
. Stethoscopes are typically used as the first line of checking respiratory and cardiac functioning before other monitoring methods such as application of Electrocardiogram (ECG) electrodes which requiring intimate skin contact at precise locations results burdensome to the patient. ECG reflects the electrical properties of the heart however it is not uncommon for structural abnormalities and defects to present themselves as abnormal sounds and murmurs 
. Graphical record of the heart sounds waveform called Phonocardiograms (PCG) can be used to assess changes in heart function.
The original stethoscope concept consisted of a brass chest piece and hollow wooden tube has slowly evolved into two main designs being the Y-tube having tubing that splits to each earpiece and Sprague-Rappaport design which has two independent tubes to each earpiece 
. The chest piece of traditional stethoscopes also improved in design over the past century with two sides used to transmit different sound wavelengths; the diaphragm is used to transmit higher frequencies, while the bell side to transmit lower frequencies 
Traditional stethoscopes will attenuate and transmit mechanical distortions picked up from the chest piece using the standing wave phenomenon and some mechanical filtering is conducted along the tubing 
. Mechanical filtering is provided by 25–30 cm length tubing, which can be constructed with neoprene, plastic or even latex, meaning there can be significant variation in frequency response between construction types 
. Moreover, tubing can add additional resonance to the already present diaphragm resonance (~900 Hz) 
, meaning that resonant peaks do not represent simple harmonics. A study by Ertel et al. 
reports that uneven frequency response with resonant peaks can lead to corruption of the acoustical signal noting that even a 3 dB attenuation can result in significant information loss.
Interpretation of the sound depends entirely upon the listeners’ perception/experience and can be heavily influenced by the surrounds as well as the acoustical properties of the listener’s ear, Resulting into a compounded signal distortion. It is well-known that bodily sounds and murmurs have low acoustical spectral energy, age-related reduction in auditory sensitivity has been linked to misinterpretation due to undetected frequencies 
. The most sensitive range for human hearing is typically ranges from 1000~3000 Hz which can be particularly problematic for identifying cardiac sounds as clinically valuable sounds lie between 20~60 Hz 
. These lower frequencies hold crucial diagnostic information and can be easily overlooked or missed during the assessment.
Antiquated designs are also subject to poor sealing and shock resistance in the tubing connection, making them particularly susceptible to signal corruption from environmental noise and thus making them far less reliable in triage assessment 
. Other noise artefacts within the signal can be generated from poor contact between the patient and chest piece and loose-fitting earpieces causing leaks and reducing perception of cardiac or respiratory events 
. As a response, Electronic Stethoscopes (ES) have emerged in the past few decades as a viable solution to the limitations of the traditional designs. Condenser microphones and piezoelectric elements, coupled with a power amplifier to control audio quality and bandwidth, are typically used to replace the bell-diaphragm components. Having higher acoustical isolation, they are ideal for use in highly noisy environments. However, their high cost which can range from several hundred to several thousand AUD make them less suitable for use in ED, where contamination and damage can easily occur 
. A study by Pinto, et al. 
also concluded that whilst features may vary between leading market ES, their performance were similar, showing advanced features are not essential for effective use in triage assessment. A low cost specifically triage assessment design, is, therefore, more desirable than the implementation of costly electronic stethoscopes marketed towards specialist practitioners.
As triage assessment is a means to determine the urgency of cases rather than the complexity of the patient’s condition, new and emerging technologies can assist in the growth of patient information recording and sharing. Consequentially, there has been a push for an engineering solution that can assist and enhance the efficiency in triage assessments to ensure timely medical intervention. Implementation of a small-scale electronic stethoscope, tailored to operate wirelessly via the central triage desk, could be used to efficiently monitor multiple patients within the ED. Integration of PC or mobile connectivity via wireless technology can further facilitate the telemonitoring of multiple physiological vital signs through simple, low-cost sensor design. Wearable systems are more sought after for implementation in these situations, where a modular device can continuously show and record patient cardiac and respiratory function in real time. Real time analysis can serve as an advanced method for the identification of key events and the removal of extraneous information, both of which are essential in effective triage assessment. Such analysis can include analysis within the frequency domain over the typical time domain as the respiratory rate is typically around 12–20 breaths per minute or 0.1–0.3 Hz 
, while typical heart rate is 60–100 beats per minute (BPM) or 1–1.67 Hz 
. Frequency domain analysis, such as the implementation of the Fast Fourier Transform (FFT), can quickly and easily depict respiratory and cardiac function by extracting the main characteristic information that would typically be embedded in time series structure 
. Cardiac analysis can be performed in both time and frequency domains, for the analysis of the R-to-R interval of the QRS complex of the electrocardiogram (ECG) which can then be used to describe any physiological changes of a patient. The significance of detected R wave in ECG and its corresponding mechanical signal from contraction of the heart muscle, play an important role in the monitoring and diagnosis of patients admitted to the ED. Further improvements of phonocardiography representation through implementation of FFT analysis have been shown by Sumarna et al. 
By enabling wearable hand free design, typically time-poor triage nurses and paramedics can continue to perform triage assessment efficiently and may achieve quicker response time to any change in physiological conditions of the patient. Additionally, wearable and personal technologies allow patients to be allocated their own devices during hospital admission meaning more objective assessments can be conducted inclusive of previous patient data. Improving the availability and sharing of quantitative data ensures that comprehensive assessment for correct treatment and diagnosis can be provided 
2. Wearable Bluetooth Triage Healthcare Monitoring System
The use of the silicone dome on the sensor was preferred as it improves the mechanical coupling with the subjects’ skin, thus assuring stable and reliable measurements. The semi-rigid silicone enclosure provided sufficient protection for the delicate piezoelectric ceramic element and the PCB which host the analogue frontend, thus making it more robust. The proposed piezo frontend design and reference ECG using the MAX30003 were sent to the ADS1247 ADC before going to the Innocom BM10_AN R2 BLU module for wireless data streaming and storage to a micro-SD card. The MAX30205 body temperature sensor, which was also cast in Pinkysil®, and the LIS2DH accelerometer for patient body potion and motion when triaging was sent directly to the MCU module, for future improvement, the positioning of the box should be fixed on the body, e.g., the belt so that the body posture can be drawn from the accelerometer sensor. The ECG, piezo front end, and accelerometer where each sampled at 300 Hz while the temperature sensor was sampled at 6.5 Hz. As such a well-rounded Bluetooth connectivity wireless triage monitoring system has been proposed within this research that would be suitable for implementation in ED and first response events.
The proposed sensor achieved performances comparable to ECG for heart rate measurement in all the three recording areas here considered. The sensor also obtained good performance for respiratory rate measurement with respect to ERB and outperformed the EDR. However, the recordings acquired on the wrist were not reliable for accurate respiratory rate extraction.
These preliminary results suggest that the proposed sensor is viable for patient monitoring, also for triage. It could offer some advantages with respect to conventional ECG and respiratory chest bands:
it is based on a cheaper sensor and requires a simpler conditioning circuit.
it requires only one measurement point, which may be positioned onto different body areas.
it does not need any electrical contact with the body and conductive gel.
it is much more robust to electromagnetic interference.
it needs much simpler processing to extract a respiration signal.
However, these promising results must be confirmed by further studies involving much more healthy subjects and patients, also during real triage assessments in ED’s.