Medical Devices for Measuring Respiratory Rate in Children: a Review

Respiratory rate is an important vital sign used for diagnosing illnesses in children as well as prioritising patient care. All children presenting acutely to hospital should have a respiratory rate measured as part of their initial and ongoing assessment. However measuring the respiratory rate remains a subjective assessment and in children can be liable to measurement error especially if the child is uncooperative. Devices to measure respiratory rate exist but many provide only an estimate of respiratory rate due to the associated methodological complexities. Some devices are used within the intensive care, post-operative or more specialised investigatory settings none however have made their way into the everyday clinical setting. A non-contact device may be better tolerated in children and not cause undue stress distorting the measurement. Further validation and adaption to the acute clinical setting is needed before such devices can supersede current methods

Non-invasive sensor methods used in monitoring newborn babies after birth, a clinical perspective

Background Reducing the global new-born mortality is a paramount challenge for humanity. There are approximately 786,323 live births in the UK each year according to the office for National Statistics; around 10% of these newborn infants require assistance during this transition after birth. Each year around, globally around 2.5 million newborns die within their first month. The main causes are complications due to prematurity and during delivery. To act in a timely manner and prevent further damage, health professionals should rely on accurate monitoring of the main vital signs heart rate and respiratory rate. Aims To present a clinical perspective on innovative, non-invasive methods to monitor heart rate and respiratory rate in babies highlighting their advantages and limitations in comparison with well-established methods. Methods Using the data collected in our recently published systematic review we highlight the barriers and facilitators for the novel sensor devices in obtaining reliable heart rate measurements. Details about difficulties related to the application of sensors and interfaces, time to display, and user feedback are explored. We also provide a unique overview of using a non-invasive respiratory rate monitoring method by extracting RR from the pulse oximetry trace of newborn babies. Results Novel sensors to monitor heart rate offer the advantages of minimally obtrusive technologies but have limitations due to movement artefact, bad sensor coupling, intermittent measurement, and poor-quality recordings compared to gold standard well established methods. Respiratory rate can be derived accurately from pleth recordings in infants. Conclusion Some limitations have been identified in current methods to monitor heart rate and respiratory rate in newborn babies. Novel minimally invasive sensors have advantages that may help clinical practice. Further research studies are needed to assess whether they are sufficiently accurate, practical, and reliable to be suitable for clinical use

Breathing Rate Estimation From the Electrocardiogram and Photoplethysmogram: A Review.

Breathing rate (BR) is a key physiological parameter used in a range of clinical settings. Despite its diagnostic and prognostic value, it is still widely measured by counting breaths manually. A plethora of algorithms have been proposed to estimate BR from the electrocardiogram (ECG) and pulse oximetry (photoplethysmogram, PPG) signals. These BR algorithms provide opportunity for automated, electronic, and unobtrusive measurement of BR in both healthcare and fitness monitoring. This paper presents a review of the literature on BR estimation from the ECG and PPG. First, the structure of BR algorithms and the mathematical techniques used at each stage are described. Second, the experimental methodologies that have been used to assess the performance of BR algorithms are reviewed, and a methodological framework for the assessment of BR algorithms is presented. Third, we outline the most pressing directions for future research, including the steps required to use BR algorithms in wearable sensors, remote video monitoring, and clinical practice

Measuring Respiratory Rate in Children

Respiratory rate is an important vital sign used in the initial and ongoing assessment of all children in hospital. It is also used as a predictor of serious deterioration in a patient's clinical condition. Measuring respiratory rate in children can be difficult to perform and time consuming, especially in an uncooperative child. Convenient electronic devices exist for the measurement of many of the vital signs yet no device is currently available that can give an accurate and rapid assessment of respiratory rate in clinical practice. In this thesis we have examined the current practices of local paediatric healthcare professionals in measuring respiratory rate and explored the levels of agreement that exist in measurements obtained. We have assessed the value of a respiratory rate measurement in detecting and identifying children at risk of clinical deterioration, comparing and contrasting it with the other vital signs. Finally we have developed a contactless portable respiratory rate monitor (CPRM) and evaluated the agreement in respiratory rate measurements between existing methods and our device. Our work has added considerably to the overall body of evidence regarding respiratory rate measurements in children. We have provided clear evidence that there are a large variety of practices used by paediatric healthcare professionals in measuring respiratory rate. We have shown an inherent variability in respiratory rate measurements between observers and firmly established that respiratory rate is a powerful predictor of clinical deterioration in children, superior to other vital signs. Finally we successfully measured respiratory rates in both adults and children using the CPRM. Our device offers a promising alternative to current methods. In its present form it does not appear accurate enough to be used in clinical practice, however plans are underway to develop the device further with revisions informed by the research in this thesis. A contactless device for accurately and quickly measuring respiratory rate could be an important tool in the assessment of unwell children in the near future

Feasibility of introducing pulse oximetry for identifying hypoxaemia among children with pneumonia in paediatric outpatient settings in Bangladesh: Generating evidence and synthesising knowledge for influencing policy, programme planning and practice

BACKGROUND: Pneumonia is the leading cause of childhood mortality, accounting for 16% of all under-5 deaths globally. Hypoxaemia is common among children with pneumonia and one of the strongest predictors of mortality. Since 2014, the World Health Organization has recommended introducing pulse oximetry for hypoxaemia identification and pneumonia classification in the Integrated Management of Childhood Illness (IMCI) services, which is a global strategy developed explicitly for outpatient management of common childhood illnesses, including pneumonia, in low-resource and high-burden settings by minimally trained health care providers. Unfortunately, there are few experiences of introducing pulse oximetry in paediatric outpatient settings and integrating it with IMCI services by adopting a health system strengthening approach. Bangladesh is one of the South Asian countries with high burdens of childhood pneumonia and hypoxaemia. Although Bangladesh has adopted the IMCI strategy and scaled up it nationally, pulse oximetry is neither recommended nor routinely used in IMCI services in Bangladesh. Successful introduction of a generic recommendation, technology, or device, like pulse oximetry, in routine services, demands an in-depth understanding of the problem and the context, followed by context-specific adaptations, demonstrations, and feasibility assessments. Also, it requires strategic and extensive engagement with policymakers and stakeholders to promote country ownership and government leadership, which are prerequisites for scalability and sustainability. OBJECTIVES AND METHOD: The overall goal of my PhD is to improve the management of childhood pneumonia by introducing and integrating pulse oximetry in routine IMCI services in Bangladesh. Furthermore, the aim is to support the Government of Bangladesh in taking an evidence-based decision in this regard. Hence, I was engaged in a series of discussions with the policymakers of the Ministry of Health and Family Welfare of the Government of Bangladesh to understand their perspectives on the existing evidence gaps and research priorities for making informed decisions regarding pulse oximetry integration. Based on these consultations, I identified my PhD objectives. RESULTS: A. Estimating the burden of hypoxaemia among children with pneumonia: I conducted a systematic review and meta-analysis by searching 11 bibliographic databases and citation indices. I reported pooled prevalence of hypoxaemia (SpO2<90%) by classification of clinical severity and by clinical settings by using the random-effects meta-analysis models. I identified 2,825 unique records from the databases, of which 57 studies met the eligibility criteria: 26 from Africa, 23 from Asia, four from South America, and four from multiple continents. The prevalence of hypoxaemia was 31% (95% CI, 26 to 36; 101,775 children) among all children with WHO-defined pneumonia, 41% (95% CI, 33 to 49; 30,483 children) among those with very severe or severe pneumonia, and 8% (95% CI, 3 to 16; 2,395 children) among those with non-severe pneumonia. The prevalence was much higher in studies conducted in emergency and inpatient settings than those conducted in outpatient settings. In 2019, we estimated that over 7 million children (95% UR, 5 to 8 million) were admitted to the hospital with hypoxaemic pneumonia. I also conducted a secondary analysis of data obtained from icddr,b-Dhaka Hospital, a secondary level referral hospital located in Dhaka, Bangladesh. I included 2,646 children aged 2-59 months admitted with WHO-defined severe pneumonia during 2014-17. On admission, the prevalence of hypoxaemia among children hospitalised with pneumonia was approximately 40% (95% CI, 38 to 42). Hypoxaemia was the strongest predictor of mortality (AOR = 11.1; 95% CI, 7.3 to 16.9) and referral (AOR = 5.9; 95% CI, 4.3 to 17.0) among other factors such as age, sex, history of fever and cough or difficulty in breathing, and severe acute malnutrition. Among those who survived, the median duration of hospital stay was 7 days (IQR, 4 to 11) in the hypoxaemic group and 6 days (IQR, 4 to 9) in the non-hypoxaemic group, and the difference was significant at p<0.001. B. Understanding the context of managing children with pneumonia, including hypoxaemia in Bangladesh: I conducted a secondary analysis using data from the 2017-18 round of the Bangladesh Demographic and Health Survey (BDHS), which adopts a nationally representative sample of households. I included 456 deaths among children under 5 years of age in our analysis. Descriptive statistics were used to present the causes, timing, and places of death with uncertainty ranges (UR). Pneumonia is the major killer (19%, 95% CI, 15.3 to 22.7), accounting for approximately 24,268 (UR, 21,626 to 26,695) under-5 deaths per year. Among children aged 1-11 months, pneumonia accounts for approximately 43% of deaths. I further conducted a secondary analysis of the Bangladesh Health Facility Survey 2017, which was conducted with a nationally representative sample including all administrative divisions and types of health facilities. More than 90% of the district hospital and sub-district hospitals and three-fourths of primary level health centres provide IMCI-based pneumonia management services. Pulse oximetry was available in 27% of the district hospitals, 18% of the sub-district level hospitals and none of the primary level health centres. Around 72% of the sub-district hospitals had the availability of one of any of the four oxygen sources (oxygen concentrators, filled oxygen cylinder with flowmeter, filled oxygen cylinder without flowmeter, and oxygen distribution system), followed by district hospitals (66%). Almost none of the primary level health centres had oxygen sources available on the day of the visit. C. Assessing the feasibility of introducing pulse oximetry in routine IMCI services: Based on literature review and expert consultations, I developed a conceptual framework, which guided the planning and implementation of a 4-step stakeholder engagement process for introducing pulse oximetry in routine IMCI services in Bangladesh. In the first step, a comprehensive desk review and key informant interviews were conducted to identify stakeholder organisations and score them based on their power and interest levels regarding IMCI implementation in Bangladesh. In the second step, two national level, two district level and five sub- district level sensitisation workshops were organised to orient all stakeholder organisations having high power or high interest regarding the importance of using pulse oximetry for pneumonia assessment and classification. In the third step, national and district level high power-high interest stakeholder organisations were involved in developing a joint action plan for introducing pulse oximetry in routine IMCI services. In the fourth step, led by a formal working group under the leadership of the Ministry of Health, we updated the National IMCI Implementation Package, including all guidelines, training manuals, services registers and referral forms in English and Bangla. Our engagement process contributed to the national decision to introduce pulse oximetry in paediatric outpatient settings and update the National IMCI Implementation Package demonstrating country ownership, government leadership and multi-partner involvement, which are steppingstones towards scalability and sustainability. However, our experience clearly delineates that stakeholder engagement is a context-driven, time-consuming, resource-intensive, iterative, and mercurial process that demands meticulous planning, prioritisation, inclusiveness, and adaptability. Based on WHO’s global recommendation in 2014, the National IMCI Programme of Bangladesh decided to introduce pulse oximetry in routine IMCI services in 2019 and developed a short training package for IMCI service providers. They decided to test the package in a relatively controlled setting for finalising the content and choice of pulse oximetry device before the demonstration in routine outpatient settings and subsequent scale-up. A cross-sectional study was conducted among children admitted to a rural district hospital. We employed 11 nurses and seven paramedics as assessors who received a one-day training on pulse oximetry. Each assessor performed at least 30 pulse oximetry measurements on children with two types of handheld devices. The assessors successfully established a stable SpO2 reading in all attempts (n=1478) except one. The median time taken was 30 seconds (IQR, 22 to 42), and within 60 seconds, 92% of attempts were successful. The median time was significantly (p<0.0001) higher among assessments conducted with a Lifebox device (36 seconds, IQR, 25 to 50) than those with a Masimo device (27 seconds, IQR, 20 to 35). Similarly, assessors aged >25 years are 4.8 (95% CI, 1.2 to 18.6) times more likely to obtain a stable reading within 60 seconds. Regarding patient-related factors, the odds of obtaining a stable SpO2 reading was 2.6 (95% CI, 1.6 to 4.2) times higher among children aged 12-59 months than among children aged 2-11 months. The National IMCI Programme of Bangladesh designed and developed a district implementation model for introducing pulse oximetry in IMCI services through stakeholder engagement and demonstrated the model in the Kushtia district by adopting a health system strengthening approach. Between December 2020 and June 2021, two assessment rounds were conducted based on WHO’s implementation research framework and outcome variables in 12 facilities involving 22 IMCI service providers and 1860 children presenting with cough/difficulty in breathing in the IMCI consultation rooms. WE OBSERVED THAT IMCI SERVICE PROVIDERS PERFORMED PULSE OXIMETRY ON ALMOST ALL ELIGIBLE CHILDREN, OF WHICH 99% OF ASSESSMENTS WERE SUCCESSFUL; 85% (95% CI, 83 TO 87) IN ONE ATTEMPT AND 69% (95% CI, 67 TO 71) WITHIN ONE MINUTE. The adherence to standards of procedures related to pulse oximetry was 92% (95% CI, 91 to 93), and agreement regarding identifying hypoxaemia was 96% (95% CI, 95 to 97). The median performance time was 36 seconds (IQR, 20 to 75), which was longer among younger children (2-11 months: 44 seconds, IQR, 22 to 78; 12-59 months: 30 seconds, IQR 18 to 53, p<0.001) and among those classified as pneumonia/severe pneumonia than as no pneumonia (41 seconds, IQR, 22 to 70; 32 seconds, IQR, 20 to 62, p<0.001). We observed improvements in all indicators in the second round of assessments. Caregivers showed positive attitudes towards using this novel technology for the assessment of children. CONCLUSION: Based on context-specific experience generated through these studies, the Government of Bangladesh decided to integrate pulse oximetry into routine IMCI services throughout Bangladesh. Furthermore, the learnings synthesised through these studies can also help convince the policymakers and managers of other LMICs with similar burdens and contexts to introduce pulse oximetry in routine settings providing outpatient-based paediatric services and contribute to achieving the target of averting all preventable childhood pneumonia deaths by 2025

Signal Processing Approaches for Cardio-Respiratory Biosignals with an Emphasis on Mobile Health Applications

We humans are constantly preoccupied with our health and physiological status. From precise measurements such as the 12-lead electrocardiograms recorded in hospitals, we have moved on to mobile acquisition devices, now as versatile as smart-watches and smart-phones. Established signal processing techniques do not cater to the particularities of mobile biomedical health monitoring applications. Moreover, although our capabilities to acquire data are growing, many underlying physiological phenomena remain poorly understood. This thesis focuses on two aspects of biomedical signal processing. First, we investigate the physiological basis of the relationship between cardiac and breathing biosignals. Second, we propose a methodology to understand and use this relationship in health monitoring applications. Part I of this dissertation examines the physiological background of the cardio-respiratory relationship and indexes based on this relationship. We propose a methodology to extract the respiratory sinus arrhythmia (RSA), which is an important aspect of this relationship. Furthermore, we propose novel indexes incorporating dynamics of the cardio-respiratory relationship, using the RSA and the phase lag between RSA and breathing. We then evaluate, systematically, existing and novel indexes under known autonomic stimuli. We demonstrate our indexes to be viable additions to the existing ones, thanks to their performance and physiological merits. Part II focuses on real-time and instantaneous methods for the estimation of the breathing parameters from cardiac activity, which is an important application of the cardio-respiratory relationship. The breathing rate is estimated from electrocardiogram and imaging photoplethysmogram recordings, using two dedicated filtering schemes, one of which is novel. Our algorithm measures this important vital rhythm in a truly real-time manner, with significantly shorter delays than existing methods. Furthermore, we identify situations, in which an important assumption regarding the estimation of breathing parameters from cardiac activity does not hold, and draw a road-map to overcome this problem. In Part III, we use indexes and methodology developed in Parts I and II in two applications for mobile health monitoring, namely, emotion recognition and sleep apnea detection from cardiac and breathing biosignals. Results on challenging datasets show that the cardio-respiratory indexes introduced in the present thesis, especially those related to the phase lag between RSA and breathing, are successful for emotion recognition and sleep apnea detection. The novel indexes reveal to be complementary to previous ones, and bring additional insight into the physiological basis of emotions and apnea episodes. To summarize, the techniques proposed in this thesis help to bypass shortcomings of previous approaches in the understanding and the estimation of cardio-respiratory coupling in real-life mobile health monitoring

Monitoring respiration in wheezy preschool children by pulse oximetry plethysmogram analysis

The aim of this study was to investigate whether respiratory information can be derived from pulse oximetry plethysmogram (pleth) recordings in acutely wheezy preschool children. A digital pulse oximeter was connected via 'Bluetooth' to a notebook computer in order to acquire pleth data. Low pass filtering and frequency analysis were used to derive respiratory rate from the pleth trace; the ratio of heart rate to respiratory rate (HR/RR) was also calculated. Recordings were obtained during acute wheezy episodes in 18 children of median age 31 months and follow-up recordings from 16 of the children were obtained when they were wheeze-free. For the acutely wheezy children, frequency analysis of the pleth waveform was within 10 breaths/min of clinical assessment in 25 of 29 recordings in 15 children. For the follow-up measurements, frequency analysis of the pleth waveform showed similarly good agreement in recordings on 15 of the 16 children. Respiratory rate was higher (p < 0.001), and HR/RR ratio was lower (p = 0.03) during acute wheeze than at follow-up. This study suggests that respiratory rate can be derived from pleth traces in wheezy preschool children