Pulse oximetry in pediatric practice

Pulse oximetry in pediatric care: Balancing advantages and limitations

BACKGROUND

Pulse oximetry has become a cornerstone technology in healthcare, providing non-invasive monitoring of oxygen saturation levels and pulse rate. Despite its widespread use, the technology has inherent limitations and challenges that must be addressed to ensure accurate and reliable patient care.

AIM

To comprehensively evaluate the advantages, limitations, and challenges of pulse oximetry in clinical practice, as well as to propose recommendations for optimizing its use.

METHODS

A systematic literature review was conducted to identify studies related to pulse oximetry and its applications in various clinical settings. Relevant articles were selected based on predefined inclusion and exclusion criteria, and data were synthesized to provide a comprehensive overview of the topic.

RESULTS

Pulse oximetry offers numerous advantages, including non-invasiveness, real-time feedback, portability, and cost-effectiveness. However, several limitations and challenges were identified, including motion artifacts, poor peripheral perfusion, ambient light interference, and patient-specific factors such as skin pigmentation and hemoglobin variants. Recommendations for optimizing pulse oximetry use include technological advancements, education and training initiatives, quality assurance protocols, and interdisciplinary collaboration.

CONCLUSION

Pulse oximetry is crucial in modern healthcare, offering invaluable insights into patients’ oxygenation status. Despite its limitations, pulse oximetry remains an indispensable tool for monitoring patients in diverse clinical settings. By implementing the recommendations outlined in this review, healthcare providers can enhance the effectiveness, accessibility, and safety of pulse oximetry monitoring, ultimately improving patient outcomes and quality of care.

Racial and skin color mediated disparities in pulse oximetry in infants and young children

Race-based and skin pigmentation-related inaccuracies in pulse oximetry have recently been highlighted in several large electronic health record-based retrospective cohort studies across diverse patient populations and healthcare settings. Overestimation of oxygen saturation by pulse oximeters, particularly in hypoxic states, is disparately higher in Black compared to other racial groups. Compared to adult literature, pediatric studies are relatively few and mostly reliant on birth certificates or maternal race-based classification of comparison groups. Neonates, infants, and young children are particularly susceptible to the adverse life-long consequences of hypoxia and hyperoxia. Successful neonatal resuscitation, precise monitoring of preterm and term neonates with predominantly lung pathology, screening for congenital heart defects, and critical decisions on home oxygen, ventilator support and medication therapies, are only a few examples of situations that are highly reliant on the accuracy of pulse oximetry. Undetected hypoxia, especially if systematically different in certain racial groups may delay appropriate therapies and may further perpetuate health care disparities. The role of biological factors that may differ between racial groups, particularly skin pigmentation that may contribute to biased pulse oximeter readings needs further evaluation. Developmental and maturational changes in skin physiology and pigmentation, and its interaction with the operating principles of pulse oximetry need further study. Importantly, clinicians should recognize the limitations of pulse oximetry and use additional objective measures of oxygenation (like co-oximetry measured arterial oxygen saturation) where hypoxia is a concern.

Hospital Environmental Factors That Influence Peripheral Oxygen Saturation Measurements: A Cross-Sectional Study

Pulse oximetry is a non-invasive, cost-effective, and generally reliable instrument measuring pulse rate and peripheral oxygen saturation (SpO2). However, these measurements can be affected by the patient's internal or external factors, including the type of pulse oximeter device (POD). (1) This study's objective was to identify potential environmental factors that may impact the measurements taken by three PODs. (2) Methods: A descriptive-analytical cross-sectional study was designed. The patients' SpO2 levels were measured using a standard monitor and two PODs owned by the professionals. The measurements were taken on the patients' fingers. Concurrently, we evaluated the surrounding environmental conditions, encompassing temperature, humidity, illuminance, and noise. (3) Results: This study involved 288 adult participants in the sample. For each 20-decibel increment in noise, there was a reduction in SpO2 by an average of 1%, whereas for every additional degree of ambient temperature, SpO2 decreased by an average of 2% (4) Conclusions: Significant correlations between SpO2 and age, as well as with noise and ambient temperature, were observed. No significant differences between oxygen saturation and lighting or humidity were observed. This study was prospectively registered with the Clinical Research Ethics Committee of Gran Canaria at the Dr. Negrín University Hospital, with protocol code 2019-247-1, and approved on 24 May 2019.

Continuous monitoring of physiological data using the patient vital status fusion score in septic critical care patients

Accurate and standardized methods for assessing the vital status of patients are crucial for patient care and scientific research. This study introduces the Patient Vital Status (PVS), which quantifies and contextualizes a patient's physical status based on continuous variables such as vital signs and deviations from age-dependent normative values. The vital signs, heart rate, oxygen saturation, respiratory rate, mean arterial blood pressure, and temperature were selected as input to the PVS pipeline. The method was applied to 70 pediatric patients in the intensive care unit (ICU), and its efficacy was evaluated by matching high values with septic events at different time points in patient care. Septic events included systemic inflammatory response syndrome (SIRS) and suspected or proven sepsis. The comparison of maximum PVS values between the presence and absence of a septic event showed significant differences (SIRS/No SIRS: p < 0.0001, η2 = 0.54; Suspected Sepsis/No Suspected Sepsis: p = 0.00047, η2 = 0.43; Proven Sepsis/No Proven Sepsis: p = 0.0055, η2 = 0.34). A further comparison between the most severe PVS in septic patients with the PVS at ICU discharge showed even higher effect sizes (SIRS: p < 0.0001, η2 = 0.8; Suspected Sepsis: p < 0.0001, η2 = 0.8; Proven Sepsis: p = 0.002, η2 = 0.84). The PVS is emerging as a data-driven tool with the potential to assess a patient's vital status in the ICU objectively. Despite real-world data challenges and potential annotation biases, it shows promise for monitoring disease progression and treatment responses. Its adaptability to different disease markers and reliance on age-dependent reference values further broaden its application possibilities. Real-time implementation of PVS in personalized patient monitoring may be a promising way to improve critical care. However, PVS requires further research and external validation to realize its true potential.

Recent Progress in Flexible and Wearable All Organic Photoplethysmography Sensors for SpO2 Monitoring

Flexible and wearable biosensors are the next-generation healthcare devices that can efficiently monitor human health conditions in day-to-day life. Moreover, the rapid growth and technological advancements in wearable optoelectronics have promoted the development of flexible organic photoplethysmography (PPG) biosensor systems that can be implanted directly onto the human body without any additional interface for efficient bio-signal monitoring. As an example, the pulse oximeter utilizes PPG signals to monitor the oxygen saturation (SpO2 ) in the blood volume using two distinct wavelengths with organic light emitting diode (OLED) as light source and an organic photodiode (OPD) as light sensor. Utilizing the flexible and soft properties of organic semiconductors, pulse oximeter can be both flexible and conformal when fabricated on thin polymeric substrates. It can also provide highly efficient human-machine interface systems that can allow for long-time biological integration and flawless measurement of signal data. In this work, a clear and systematic overview of the latest progress and updates in flexible and wearable all-organic pulse oximetry sensors for SpO2 monitoring, including design and geometry, processing techniques and materials, encapsulation and various factors affecting the device performance, and limitations are provided. Finally, some of the research challenges and future opportunities in the field are mentioned.

A Template for Translational Bioinformatics: Facilitating Multimodal Data Analyses in Preclinical Models of Neurological Injury

Background

Pediatric neurological injury and disease is a critical public health issue due to increasing rates of survival from primary injuries (e.g., cardiac arrest, traumatic brain injury) and a lack of monitoring technologies and therapeutics for the treatment of secondary neurological injury. Translational, preclinical research facilitates the development of solutions to address this growing issue but is hindered by a lack of available data frameworks and standards for the management, processing, and analysis of multimodal data sets.

Methods

Here, we present a generalizable data framework that was implemented for large animal research at the Children's Hospital of Philadelphia to address this technological gap. The presented framework culminates in an interactive dashboard for exploratory analysis and filtered data set download.

Results

Compared with existing clinical and preclinical data management solutions, the presented framework accommodates heterogeneous data types (single measure, repeated measures, time series, and imaging), integrates data sets across various experimental models, and facilitates dynamic visualization of integrated data sets. We present a use case of this framework for predictive model development for intra-arrest prediction of cardiopulmonary resuscitation outcome.

Conclusions

The described preclinical data framework may serve as a template to aid in data management efforts in other translational research labs that generate heterogeneous data sets and require a dynamic platform that can easily evolve alongside their research.

Towards Simultaneous Noninvasive Arterial and Venous Oxygenation Monitoring with Wearable E-Tattoo

While noninvasive arterial blood oxygenation is easily estimated using peripheral pulse oximeters, noninvasive venous blood oxygenation monitoring is still a critical unmet need. Critical conditions that lead to inefficient extraction of oxygen from the blood, such as sepsis or shock, can only be detected by analyzing the oxygen content of the venous blood. In this work, we introduce a soft wearable e-tattoo sensor that simultaneously measures the arterial and venous pulses from the wrist. First, we prove that the origin of the signal is venous pulsatility. We hypothesize that a significant obstacle for simultaneous SaO2 and SvO2 extraction is the close proximity of the artery and vein, thus leading to crosstalk. We characterize this crosstalk with simulation, in vitro, and in vivo experiments. Finally, we offer a potential solution for minimizing the crosstalk through spatial filtering.Clinical Relevance- This lays foundational work for a novel method of noninvasively and simultaneously measuring arterial and venous blood oxygenation to improve clinical diagnoses of sepsis, shock, and metabolic abnormalities.

A Hemoglobin Variant Causing an Unexplained Low Oxygen Saturation by Pulse Oximetry: Two Case Reports

Pulse oximetry is now routinely used in neonatal resuscitation and for neonatal screening for congenital heart diseases. Beyond respiratory and cardiac diseases, hemoglobin (Hb) variants must be included in the differential diagnosis of low oxygen saturation detected by pulse oximetry. We aim to describe two cases of fetal Hb variant (heterozygous γ-globin gene (HBG1) mutation in exon 2 c.202G>A (p.Val68Met)), which was identified in two unrelated newborns.

Near-infrared spectroscopy in the medical management of infants

Near-infrared spectroscopy (NIRS) is a technology that is easy to use and can provide helpful information about organ oxygenation and perfusion by measuring regional tissue oxygen saturation (rSO2) with near-infrared light. The sensors can be placed in different anatomical locations to monitor rSO2 levels in several organs. While NIRS is not without limitations, this equipment is now becoming increasingly integrated into modern healthcare practice with the goal of achieving better outcomes for patients. It can be particularly applicable in the monitoring of pediatric patients because of their size, and especially so in infant patients. Infants are ideal for NIRS monitoring as nearly all of their vital organs lie near the skin surface which near-infrared light penetrates through. In addition, infants are a difficult population to evaluate with traditional invasive monitoring techniques that normally rely on the use of larger catheters and maintaining vascular access. Pediatric clinicians can observe rSO2 values in order to gain insight about tissue perfusion, oxygenation, and the metabolic status of their patients. In this way, NIRS can be used in a non-invasive manner to either continuously or periodically check rSO2. Because of these attributes and capabilities, NIRS can be used in various pediatric inpatient settings and on a variety of patients who require monitoring. The primary objective of this review is to provide pediatric clinicians with a general understanding of how NIRS works, to discuss how it currently is being studied and employed, and how NIRS could be increasingly used in the near future, all with a focus on infant management.

Modelling the cost-effectiveness of pulse oximetry in primary care management of acute respiratory infection in rural northern Thailand

OBJECTIVES

We aimed to determine the cost-effectiveness of supplementing standard care with pulse oximetry among children <5 years with acute respiratory infection (ARI) presenting to 32 primary care units in a rural district (total population 241,436) of Chiang Rai province, Thailand, and to assess the economic effects of extending pulse oximetry to older patients with ARI in this setting.

METHODS

We performed a model-based cost-effectiveness analysis from a health systems perspective. Decision trees were constructed for three patient categories (children <5 years, children 5-14 years, and adults), with a 1-year time horizon. Model parameters were based on data from 49,958 patients included in a review of acute infection management in the 32 primary care units, published studies, and procurement price lists. Parameters were varied in deterministic sensitivity analyses. Costs were expressed in 2021 US dollars with a willingness-to-pay threshold per DALY averted of $8624.

RESULTS

The annual direct cost of pulse oximetry, associated staff, training, and monitoring was $24,243. It reduced deaths from severe lower respiratory tract infections in children <5 years by 0.19 per 100,000 patients annually. In our population of 14,075 children <5 years, this was equivalent to 2.0 DALYs averted per year. When downstream costs such as those related to hospitalisation and inappropriate antibiotic prescription were considered, pulse oximetry dominated standard care, saving $12,757 annually. This intervention yielded smaller mortality gains in older patients but resulted in further cost savings, primarily by reducing inappropriate antibiotic prescriptions in these age groups. The dominance of the intervention was also demonstrated in all sensitivity analyses.

CONCLUSIONS

Pulse oximetry is a life-saving, cost-effective adjunct in ARI primary care management in rural northern Thailand. This finding is likely to be generalisable to neighbouring countries with similar disease epidemiology and health systems.

Interpretation of Oxygen Saturation in Congenital Heart Disease: Fact and Fallacy

Oxygen saturation is the percentage of hemoglobin that is saturated with oxygen, converting it to oxyhemoglobin. Oxygen saturation is a critical part of the physical examination of children with congenital heart disease (CHD). The expected oxygen saturation of a patient with CHD depends on their anatomical lesion, their previous surgeries, and any additional pulmonary or systemic pathology that may derange their saturation. Oxygen saturation can be noninvasively measured using pulse oximetry. Pulse oximetry is based on the differential absorption of infrared and red light by oxyhemoglobin and deoxyhemoglobin, with the former absorbing more infrared than the latter. Pulse oximetry readings may be inaccurate in settings of low cardiac output, peripheral vasoconstriction, arrhythmia, hypothermia, and venous pulsations. The use of pulse oximetry in the care of a child with CHD begins with the newborn critical CHD screen. A failed screen indicates a need for further investigation, such as repeated pulse oximetry or echocardiography. The oxyhemoglobin dissociation curve may be used to estimate the partial pressure of oxygen in the blood at various oxygen saturations. It is also a marker of the affinity of hemoglobin for oxygen, with a right-shifted curve indicating a higher oxygen tension needed to saturate hemoglobin. This is a helpful adaptation of the body to situations of stress such as fever, acidosis, and hypercapnia. An understanding of these concepts is paramount for providers caring for patients with known or potential CHD in any setting to appropriately interpret and respond to abnormal saturations for each child.

Clinical feasibility of an advanced neonatal epidermal multiparameter continuous monitoring technology in a large public maternity hospital in Nairobi, Kenya

Clinically feasible multiparameter continuous physiological monitoring technologies are needed for use in resource-constrained African healthcare facilities to allow for early detection of critical events and timely intervention for major morbidities in high-risk neonates. We conducted a prospective clinical feasibility study of a novel multiparameter continuous physiological monitoring technology in neonates at Pumwani Maternity Hospital in Nairobi, Kenya. To assess feasibility, we compared the performance of Sibel's Advanced Neonatal Epidermal (ANNE) technology to reference technologies, including Masimo's Rad-97 pulse CO-oximeter with capnography technology for heart rate (HR), respiratory rate (RR), and oxygen saturation (SpO₂) measurements and Spengler's Tempo Easy non-contact infrared thermometer for temperature measurements. We evaluated key performance criteria such as up-time, clinical event detection performance, and the agreement of measurements compared to those from the reference technologies in an uncontrolled, real-world setting. Between September 15 and December 15, 2020, we collected and analyzed 503 h of ANNE data from 109 enrolled neonates. ANNE's up-time was 42 (11%) h more for HR, 77 (25%) h more for RR, and 6 (2%) h less for SpO₂ compared to the Rad-97. However, ANNE's ratio of up-time to total attached time was less than Rad-97's for HR (0.79 vs 0.86), RR (0.68 vs. 0.79), and SpO₂ (0.69 vs 0.86). ANNE demonstrated adequate performance in identifying high and low HR and RR and high temperature events; however, showed relatively poor performance for low SpO₂ events. The normalized spread of limits of agreement were 8.4% for HR and 52.2% for RR and the normalized root-mean-square deviation was 4.4% for SpO₂. Temperature agreement showed a spread of limits of agreement of 2.8 °C. The a priori-identified optimal limits were met for HR and temperature but not for RR or SpO₂. ANNE was clinically feasible for HR and temperature but not RR and SpO₂ as demonstrated by the technology's up-time, clinical event detection performance, and the agreement of measurements compared to those from the reference technologies.

Detection of hypoxia by near-infrared spectroscopy and pulse oximetry: a comparative study

SIGNIFICANCE

Pulse oximetry is widely used in clinical practice to monitor changes in arterial oxygen saturation (SpO2). However, decreases in SpO2 can be delayed relative to the actual clinical event, and near-infrared spectroscopy (NIRS) may detect alterations in oxygenation earlier than pulse oximetry, as shown in previous cerebral oxygenation monitoring studies.

AIM

We aim to compare the response of transcutaneous muscle NIRS measures of the tissue saturation index with pulse oximetry SpO2 during hypoxia.

APPROACH

Episodes of acute hypoxia were induced in nine anesthetized Yucatan miniature pigs. A standard pulse oximeter was attached to the ear of the animal, and a transcutaneous NIRS sensor was placed on the hind limb muscle. Hypoxia was induced by detaching the ventilator from the animal and reattaching it once the pulse oximeter reported 70% SpO2.

RESULTS

Twenty-four episodes of acute hypoxia were analyzed. Upon the start of hypoxia, the transcutaneous NIRS measures changed in 5.3 ± 0.4 s, whereas the pulse oximetry measures changed in 14.9 ± 1.0 s (p < 0.0001).

CONCLUSIONS

Transcutaneous muscle NIRS can detect the effects of hypoxia significantly sooner than pulse oximetry in the Yucatan miniature pig. A transcutaneous NIRS sensor may be used as an earlier detector of oxygen saturation changes in the clinical setting than the standard pulse oximeter.

Utility and Impact Analysis of Inpatient Pediatric Physiologic Monitoring

This study aimed to study the practice and effect of monitoring hospitalized pediatric patients in terms the length of stay (LOS). We have performed a prospective, observational study of pediatric patients in the general ward from October to December 2016. We have recorded the use of cardiac monitor, pulse oximeter, or both, and as per physician order at patient admission. We have studied the proportions of monitoring in different patient groups. We have applied a linear regression model to investigate the relationship between LOS and cardiopulmonary monitoring, orders, and medical complexity. Among 399 patients, patients with cardiac and pulse oximeter monitoring with orders were 68 and 82%, respectively. The pulmonary group had more monitoring than the neurology group of patients. LOS was shorter in patients without monitoring; the median difference for the cardiac monitoring was one day (interquartile range [IQR] = 1), and the pulse oximeter was 0.5 days (IQR = 1). Cardiac monitoring order increased LOS by 22% (95% confidence interval [CI]: 0.5, 48%) and complex past medical history increased it by 25% (95% CI: 4, 51%). Our study highlights the variable practice in using monitors, emphasizing a standardized approach. The judicious use of monitoring may reduce prolonged hospitalization. Selective use of physiologic monitoring of ill-appearing or at risk of hypoxemia or cardiac dysrhythmia will reduce overuse.

Excessive Oxygen Supplementation in the First Day of Mechanical Ventilation Is Associated With Multiple Organ Dysfunction and Death in Critically Ill Children

OBJECTIVES

To determine if greater cumulative exposure to oxygen despite adequate oxygenation over the first 24 hours of mechanical ventilation is associated with multiple organ dysfunction syndrome at 7 days and inhospital mortality in critically ill children.

DESIGN

Retrospective, observational cohort study.

SETTING

Two urban, academic PICUs.

PATIENTS

Patients less than 18 years old who required mechanical ventilation within 3 days of admission between 2010 and 2018 (Lurie Children's Hospital) or 2010 and 2016 (Comer Children's Hospital).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

There were 5,406 mechanically ventilated patients, of which 960 (17.8%) had multiple organ dysfunction syndrome on day 7 of admission and 319 died (5.9%) during their hospitalization. Cumulative exposure to greater amounts of supplemental oxygen, while peripheral oxygen saturation was 95% or more during the first 24 hours of mechanical ventilation was independently associated with an increased risk of both multiple organ dysfunction syndrome on day 7 and inhospital mortality after adjusting for confounders. Patients in the highest quartile of cumulative oxygen exposure had an increased odds of multiple organ dysfunction syndrome on day 7 (adjusted odds ratio, 3.9; 95% CI, 2.7-5.9) and inhospital mortality (adjusted odds ratio, 1.7; 95% CI, 1.1-2.9), when compared with those in the lowest quartile of cumulative oxygen exposure after adjusting for age, presence of multiple organ dysfunction syndrome on day 1 of mechanical ventilation, immunocompromised state, and study site.

CONCLUSIONS

Greater cumulative exposure to excess supplemental oxygen in the first 24 hours of mechanical ventilation is independently associated with an increased risk of multiple organ dysfunction syndrome on day 7 of admission and inhospital mortality in critically ill children.

Oxygen saturation targets in pediatric respiratory disease

BACKGROUND

The present study aimed to assess the appropriate oxygen saturation target in patients with pediatric respiratory diseases by lowering the oxygen saturation target from SpO₂ 94% to 90%. No previous study has explored appropriate oxygen saturation targets in respiratory diseases other than bronchiolitis.

METHODS

The present, prospective, single-arm intervention trial enrolled pediatric inpatients with bronchiolitis, bronchitis, pneumonia, and asthma. The oxygen saturation target was lowered from SpO₂ 94% to 90% after the patients' general condition improved. The patients continued to be observed for 12 h after achieving SpO₂ 94%. The duration from the first cut-off point (SpO₂ 90% for 12 h without oxygen) to the second cut-off point (SpO₂ 94% for 12 h) was then evaluated.

RESULTS

In total, 248 patients completed the study. Patients with bronchiolitis, bronchitis, pneumonia, and asthma had an interval between the two cut-off points of 23.9, 15.5, 19.1, and 13.8 h, respectively, (mean 17.2 h; 95% confidence interval 15.0-19.5).

CONCLUSIONS

In generally healthy children, setting the oxygen saturation target at SpO₂ 90% after confirming improvement in their general condition was safe. The time required for increasing SpO₂ from 90% to 94% was longest in the patients with bronchiolitis.

Hypoxemia, hypoglycemia and IMCI danger signs in pediatric outpatients in Malawi

Hypoxemia and hypoglycemia are known risks for mortality in children in low-income settings. Routine screening with pulse oximetry and blood glucose assessments for outpatients could assist in early identification of high-risk children. We assessed the prevalence of hypoglycemia and hypoxemia, and the overlap with Integrated Management of Childhood Illness (IMCI) general danger signs, among children seeking outpatient care in Malawi. A cross-sectional study was conducted at 14 government primary care facilities, four rural hospitals and one district referral hospital in Mchinji district, Malawi from August 2019-April 2020. All children aged 0-12 years seeking care with an acute illness were assessed on one day per month in each facility. Study research assistants measured oxygen saturation using Lifebox LB-01 pulse oximeter and blood glucose was assessed with AccuCheck Aviva glucometers. World Health Organization definitions were used for severe hypoglycemia (<2.5mmol/l) and hypoxemia (SpO2 <90%). Moderate hypoglycemia (2.5-4.0mmol/l) and hypoxemia (SpO2 90-93%) were also calculated and prevalence levels compared between those with and without IMCI danger signs using chi2 tests. In total 2,943 children were enrolled, with a median age of 41 (range: 0-144) months. The prevalence of severe hypoxemia was 0.6% and moderate hypoxemia 5.4%. Severe hypoglycemia was present in 0.1% of children and moderate hypoglycemia in 11.1%. IMCI general danger signs were present in 29.3% of children. All severely hypoglycemic children presented with an IMCI danger sign (p <0.001), but only 23.5% of the severely hypoxemic and 31.7% of the moderately hypoxemic children. We conclude that while the prevalence of severe hypoxemia and hypoglycemia were low, moderate levels were not uncommon and could potentially be useful as an objective tool to determine referral needs. IMCI danger signs identified hypoglycemic children, but results highlight the challenge to detect hypoxemia. Future studies should explore case management strategies for moderate hypoxemia and hypoglycemia.

Performance of Automated Point-of-Care Respiratory Rate Counting versus Manual Counting in Children under Five Admitted with Severe Febrile Illness to Kisantu Hospital, DR Congo

To improve the early recognition of danger signs in children with severe febrile illness in low resource settings, WHO promotes automated respiratory rate (RR) counting, but its performance is unknown in this population. Therefore, we prospectively evaluated the field performance of automated point-of-care plethysmography-based RR counting in hospitalized children with severe febrile illness (<5 years) in DR Congo. A trained research nurse simultaneously counted the RR manually (comparative method) and automatically with the Masimo Rad G pulse oximeter. Valid paired RR measurements were obtained in 202 (83.1%) children, among whom 43.1% (87/202) had fast breathing according to WHO criteria based on manual counting. Automated counting frequently underestimated the RR (median difference of -1 breath/minute; p2.5-p97.5 limits of agreement: -34-6), particularly at higher RR. This resulted in a failure to detect fast breathing in 24.1% (21/87) of fast breathing children (positive percent agreement: 75.9%), which was not explained by clinical characteristics (p > 0.05). Children without fast breathing were mostly correctly classified (negative percent agreement: 98.3%). In conclusion, in the present setting the automated RR counter performed insufficiently to facilitate the early recognition of danger signs in children with severe febrile illness, given wide limits of agreement and a too low positive percent agreement.

[Pulmonary function testing in the cat - an overview]

This article provides an overview of currently available pulmonary function tests in cats, divided into invasive and non-invasive methods. Invasive techniques comprise arterial blood gas analysis and measurement of pulmonary mechanics. Non-invasive techniques include pulse oximetry and capnography, as well as methods not yet integrated into everyday practice such as tidal breathing airflow-volume loops, whole-body barometric plethysmography and thorax compression. In this article, the background, execution, interpretation, and limitations of each test are discussed. Proper performance and assessment of pulmonary function measurements may aid in understanding the pathophysiology of feline respiratory disease and in increasing objectivity when assessing the existing disease and treatment efficacy.

Performance of five pulse oximeters to detect hypoxaemia as an indicator of severe illness in children under five by frontline health workers in low resource settings - A prospective, multicentre, single-blinded, trial in Cambodia, Ethiopia, South Sudan, and Uganda

BACKGROUND

Low blood oxygen saturation (SpO₂), or hypoxaemia, is an indicator of severe illness in children. Pulse oximetry is a globally accepted, non-invasive method to identify hypoxaemia, but rarely available outside higher-level facilities in resource-constrained countries. This study aims to evaluate the performance of different types of pulse oximeters amongst frontline health workers in Cambodia, Ethiopia, South Sudan, and Uganda.

METHODS

Five pulse oximeters (POx) which passed laboratory testing, out of an initial 32 potential pulse oximeters, were evaluated by frontline health workers for performance, defined as agreement between the SpO₂ measurements of the test device and the reference standard. The study protocol is registered with the Australia New Zealand Clinical Trials Registry (Ref: ACTRrn12615000348550).

FINDINGS

Two finger-tip pulse oximeters (Contec and Devon), two handheld pulse oximeters (Lifebox and Utech), and one phone pulse oximeter (Masimo) passed the laboratory testing. They were evaluated for performance on 1,313 children under five years old by 207 frontline health workers between February and May 2015. Phone and handheld pulse oximeters had greater overall agreement with the reference standard (56%; 95% CI 0.52 - 0.60 to 68%; 95% CI 0.65 - 0.71) than the finger-tip POx (31%; 95% CI 0.26 to 0.36 and 47%; 95% CI 0.42 to 0.52). Fingertip POx performance was substantially lower in the 0-2 month olds; having just 17% and 25% agreement. The finger-tip devices more often underreported SpO₂ readings (mean difference -7.9%; 95%CI -8.6,-7.2 and -3.9%; 95%CI -4.4,-3.4), and therefore over diagnosed hypoxaemia in the children assessed.

INTERPRETATION

While the Masimo phone pulse oximeter performed best, all handheld POx with age-specific probes performed well in the hands of frontline health workers, further highlighting their suitability as a screening tool of severe illness. The poor performance of the fingertip POx suggests they should not be used in children under five by frontline health workers. It is essential that POx are performance tested on children in routine settings (in vivo), not only in laboratories or controlled settings (in vitro), before being introduced at scale.

FUNDING

Bill & Melinda Gates Foundation [OPP1054367].

Analysis of the difference in pulse oxygen saturation between the ventral and dorsal fingers

AIM

This study aimed to investigate the effect of different probe placements on the ventral and dorsal sides of the same finger using pulse oxygen saturation monitoring.

METHODS

This clinical trial used a convenience sampling method in patients admitted to the Second Hospital of Hebei Medical University. We enrolled 1330 patients from March to July 2018, including patients who were hospitalized in the intensive care unit (n = 258) and in the general ward (n = 1072). Pulse oxygen saturation measurements obtained from the ventral and dorsal sides of the same finger were compared. This work adhered to the STROBE checklist requirements.

RESULTS

We found that pulse oxygen saturation measurements between the dorsal and ventral sides of a finger were not affected by different fingers, disease types, the application of a ventilator, vasoactive drugs, the conscious state of the patient or the instrument model.

CONCLUSION

Our findings suggested no significant difference in saturation measurements with variation in the placement of the pulse oxygen saturation measurement instrument between the dorsal and ventral sides of a finger, regardless of illness severity. We believe that these results could simplify the monitoring procedures performed by nurses and eliminate worries concerning the inaccuracy of data because of varied probe positions.

Utility of Point-of-Care Lung Ultrasonography for Evaluating Acute Chest Syndrome in Young Patients With Sickle Cell Disease

STUDY OBJECTIVE

Acute chest syndrome is a leading cause of mortality in patients with sickle cell disease (SCD). Because early detection of acute chest syndrome is directly tied to prognosis, young patients with SCD undergo countless chest radiography screenings throughout their lifetime for commonly occurring acute chest syndrome risk factors such as fever, chest pain, or cough. Chest radiography is not an ideal screening method because it is associated with radiation exposure, which accumulates with repeated imaging. Point-of-care lung ultrasonography is a nonradiating imaging modality that has been used to identify other lung pathology and may have a role in SCD. The goal of this study was to determine the accuracy of point-of-care lung ultrasound to identify an infiltrate suggestive of acute chest syndrome in patients with SCD compared to chest radiography as the gold standard.

METHODS

This was a prospective observational study in 2 urban pediatric emergency departments to evaluate the accuracy of point-of-care lung ultrasonography in identifying patients with SCD who were aged 0 to 21 years and had an infiltrate suggestive of acute chest syndrome compared with chest radiography. Clinicians and trainees with point-of-care lung ultrasonographic training obtained informed consent and performed investigational point-of-care lung ultrasonography to evaluate for lung consolidation. A blinded point-of-care lung ultrasonographic expert reviewed results for quality assurance and agreement. Accuracy, sensitivity, specificity, likelihood ratios, and positive and negative predictive value were calculated for point-of-care lung ultrasonography test performance characteristics, with chest radiography as a reference standard.

RESULTS

Point-of-care lung ultrasonography was performed on 191 SCD patients with a mean age of 8 years; 41% were female patients, and there was a 17% prevalence of acute chest syndrome. Accuracy of point-of-care lung ultrasonography to detected acute chest syndrome was 92%, sensitivity was 88%, and specificity was 93% compared with that for chest radiography.

CONCLUSION

Point-of-care lung ultrasonography is a feasible alternative to chest radiography for screening for acute chest syndrome in young patients with SCD. Further studies are needed to determine how this test performs within clinical practice.

Abnormal Vital Sign Recognition and Provider Notification in the Pediatric Emergency Department

INTRODUCTION

Vital signs measurements aid in the early identification of patients at risk of clinical deterioration and determining the severity of illness. Health care providers rely on registered nurses to document vital signs and communicate abnormalities. The purpose of this project was to improve the provider notification process regarding abnormal vital signs in a pediatric emergency department.

METHOD

A best practice advisory (BPA) was piloted by the advanced practice providers in the pediatric emergency department. To evaluate the effects of the BPA, a mixed-methods study was employed.

RESULTS

Implementation of the BPA improved the provider notification process and enhanced clinical decision making. The percentage of patients discharged home with abnormal respiratory rates (10.9% vs. 5.9%, p = .31), abnormal temperatures (15.6% vs. 7.5%, p = .14), and abnormal heart rates (25% vs. 11.9%, p = .11) improved.

DISCUSSION

Creation and implementation of the BPA improved the abnormal vital sign communication process to providers at this single institution.

Pulse oximetry curves in healthy children living at moderate altitude: a cross-sectional study from the Ecuadorian Andes

Background

In populations above 3,000 meters above sea level (m.a.s.l.) normal values of oxygen saturation (SpO2) above 90% have been reported. Few studies have been conducted in cities of moderate altitude (between 2,500 and 3,000 m a.s.l). We set out to describe the range of SpO2 values measured with a pulse oximeter in healthy children between 1 month and 12 years of age living in an Ecuadorian Andean city.

Methods

A cross-sectional study was carried out in Quito, Ecuador, located at 2,810 m a.s.l. SpO2 measurement in healthy children of ages ranging from 1 month to 12 years of age residents in the city were recorded by pulse oximetry. Age and gender were recorded, and median and 2.5th and 5th percentile were drawn. Non parametric tests were used to compare differences in SpO2 values by age and gender.

Results

1,378 healthy children were included for the study, 719 (52.2%) males. The median SpO2 for the entire population was 94.5%. No differences were observed between SpO2 median values by age and gender. The 2.5th percentile for global SpO2 measurements was 90%, in children under 5 years of age was 91% and it was 90% in children older than 7.

Conclusions

Our results provide SpO2 values for healthy children from 1 to 12 years old residents in Quito, a city of moderate altitude. The SpO2 percentile curve could contribute as a healthy range for the clinical evaluation of children residing at this altitude.

[Guidelines for the Management of Community Acquired Pneumonia in Children and Adolescents (Pediatric Community Acquired Pneumonia, pCAP) - Issued under the Responsibility of the German Society for Pediatric Infectious Diseases (DGPI) and the German Society for Pediatric Pulmonology (GPP)]

The present guideline aims to improve the evidence-based management of children and adolescents with pediatric community-acquired pneumonia (pCAP). Despite a prevalence of approx. 300 cases per 100 000 children per year in Central Europe, mortality is very low. Prevention includes infection control measures and comprehensive immunization. The diagnosis can and should be established clinically by history, physical examination and pulse oximetry, with fever and tachypnea as cardinal features. Additional signs or symptoms such as severely compromised general condition, poor feeding, dehydration, altered consciousness or seizures discriminate subjects with severe pCAP from those with non-severe pCAP. Within an age-dependent spectrum of infectious agents, bacterial etiology cannot be reliably differentiated from viral or mixed infections by currently available biomarkers. Most children and adolescents with non-severe pCAP and oxygen saturation > 92 % can be managed as outpatients without laboratory/microbiology workup or imaging. Anti-infective agents are not generally indicated and can be safely withheld especially in children of young age, with wheeze or other indices suggesting a viral origin. For calculated antibiotic therapy, aminopenicillins are the preferred drug class with comparable efficacy of oral (amoxicillin) and intravenous administration (ampicillin). Follow-up evaluation after 48 - 72 hours is mandatory for the assessment of clinical course, treatment success and potential complications such as parapneumonic pleural effusion or empyema, which may necessitate alternative or add-on therapy.

Pulse oximeter with integrated management of childhood illness for diagnosis of severe childhood pneumonia at rural health institutions in Southern Ethiopia: results from a cluster-randomised controlled trial

OBJECTIVE

To assess whether pulse oximetry improves health workers' performance in diagnosing severe childhood pneumonia at health centres in Southern Ethiopia.

DESIGN

Parallel cluster-randomised trial.

SETTING

Government primary health centres.

PARTICIPANTS

Twenty-four health centres that treat at least one pneumonia case per day in Southern Ethiopia. Children aged between 2 months and 59 months who present at health facilities with cough or difficulty breathing were recruited in the study from September 2018 to April 2019.

INTERVENTION ARM

Use of the Integrated Management of Childhood Illness (IMCI) algorithm and pulse oximeter.

CONTROL ARM

Use of the IMCI algorithm only.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome was the proportion of children diagnosed with severe pneumonia. Secondary outcomes included referred cases of severe pneumonia and treatment failure on day 14 after enrolment.

RESULT

Twenty-four health centres were randomised into intervention (928 children) and control arms (876 children). The proportion of children with severe pneumonia was 15.9% (148 of 928 children) in the intervention arm and 3.9% (34 of 876 children) in the control arm. After adjusting for differences in baseline variables children in the intervention arm were more likely to be diagnosed as severe pneumonia cases as compared with those in the control arm (adjusted OR: 5.4, 95% CI 2.0 to 14.3, p=0.001).

CONCLUSION

The combined use of IMCI and pulse oximetry in health centres increased the number of diagnosed severe childhood pneumonia.

TRIAL REGISTRATION NUMBER

PACTR201807164196402.

Pulse Oximetry Screening Has Not Changed Timing of Diagnosis or Mortality of Critical Congenital Heart Disease

This study evaluates the effectiveness of mandatory pulse oximetry screening. The objective is to evaluate whether mandatory pulse oximetry testing had decreased the late critical congenital heart disease (CCHD) diagnosis rate and reduced mortality in neonatal subjects. This was a single center, retrospective cohort study comparing the timing of diagnosis of CCHD between neonates undergoing cardiac surgery in 2009-2010, prior to mandatory pulse oximetry screening, and neonates in 2015-2016, after mandatory pulse oximetry screening was instituted. Follow-up was for 1 year. We defined CCHD as lesions requiring surgical correction within 30 days of life. Exclusions included: pacemaker insertions, vascular ring divisions, closure of patent ductus arteriosus, arterial cutdown, or extracorporeal membrane oxygenation cannulation without structural heart disease as the sole procedure, or if subjects were born at home. Infants diagnosed prior to discharge from birth hospital were defined as early postnatal; late postnatal subjects were diagnosed after birth hospital discharge. In-hospital mortality and 1-year mortality were measured. A total of 527 neonates were included; 251 (47.6%) comprised the pre-mandatory pulse oximetry screening cohort (2009-2010). Only 3.6% of the 2009-2010 cohort and 4.3% of the 2015-2016 cohort were diagnosed late (p = 0.66). One-year mortality decreased during the study period (17.2% in 2009-2010 vs 10.5% in 2015-2016, p = 0.03). There were no deaths in the late CCHD diagnosis groups. Mandatory pulse oximetry screening legislation has not changed the late postnatal diagnosis rate at our institution. Mortality for neonatal CCHD has declined, but this decline is not attributable to mandatory pulse oximetry screening.

Discerning Post Anesthesia Readiness for Transition (DPART): A Measurement Tool

PURPOSE

To develop a valid reliable measurement tool that accurately quantifies postanesthesia recuperation in adult and pediatric patients.

DESIGN

A descriptive factor-isolating design guided by measurement theory.

METHODS

Instrument development was based on collaborative discussions of professional evidence. A five-person expert panel was consulted for content and face validity. Reliability testing took place in the adult and pediatric postanesthesia care units.

FINDINGS

The expert panel's final review yielded a kappa statistic of 1 and scale content validity index based on universal agreement between raters of 1, suggesting high content validity. Reliability testing yielded a kappa statistic of 1, demonstrating complete agreement for all items.

CONCLUSIONS

The Discerning Post Anesthesia Readiness for Transition measurement tool is a valid and reliable instrument that can be used in practice or future research to assess postanesthesia recuperation in pediatric and adult patients.

Comparison of pulse oximetry and earlobe blood gas with CO-oximetry in children with sickle cell disease: a retrospective review

OBJECTIVES

To investigate the agreement between pulse oximetry (SpO₂) and oxygen saturation (SaO₂) measured by CO-oximetry on arterialised earlobe blood gas (EBG) in children and adolescents with sickle cell disease (SCD).

DESIGN AND SETTING

We retrospectively reviewed 39 simultaneous and paired SaO₂ EBG and SpO₂ measurements from 33 ambulatory patients with SCD (32 subjects with Haemoglobin SS and one with Haemoglobin Sß⁺, 52% male, mean±SD age 11.0±3.6, age range 5-18). Measurements were performed between 2012 and 2015 when participants were asymptomatic. Hypoxaemia was defined as SaO₂ ≤93%. A Bland-Altman analysis was performed to assess the accuracy of SpO₂ as compared with EBG SaO₂.

RESULTS

The mean±SD SpO₂ and SaO₂ values in the same patients were, respectively, 93.6%±3.7% and 94.3%±2.9%. The bias SpO₂-SaO₂ was -0.7% (95% limits of agreement from -5.4% to 4.1%) and precision was 2.5%. In 9/39 (23%) cases, the difference in SpO₂-SaO₂ was greater than the expected error range ±2%, with SaO₂ more often underestimated by SpO₂ (6/9), especially at SpO₂values ≤93%. Thirteen participants (33%) were hypoxaemic. The sensitivity of SpO₂ for hypoxaemia was 100%, specificity 85% and positive predictive value 76%.

CONCLUSIONS

Pulse oximetry was inaccurate in almost a quarter of measurements in ambulatory paediatric patients with SCD, especially at SpO₂values ≤93%. In these cases, oxygen saturation can be confirmed through EBG CO-oximetry, which is easier to perform and less painful than traditional arterial blood sampling.

Frequency of Pediatric Acute Respiratory Distress Syndrome Based on Oxygen Saturation Index in Pediatric Intensive Care Unit of a Developing Country

Objectives

To determine the frequency of pediatric acute respiratory distress syndrome based on oxygen saturation index in pediatric intensive care unit of a developing country.

Methods

We conducted a retrospective study of all children admitted in pediatric intensive care unit (PICU) of Aga Khan University Hospital, Karachi from July 2017 to June 2018 with respiratory rate >40 breaths/minute, shortness of breath, and bluish discoloration of skin and mucous membranes. The diagnosis of acute respiratory distress syndrome (ARDS) was made on the basis of standard operational definitions as mentioned (fulfilling criteria for ARDS).

Results

During the one-year study period 150 patients with age range of one month to 16 years were admitted fulfilling the inclusion criteria. Mean age was 38.27 ± 53.13 months, and 92 (61.33%) were male with male to female ratio of 1.6:1. Mean duration of symptoms was 1.23 ± 0.42 days. Frequency of pediatric acute respiratory distress syndrome using oxygen saturation index admitted in a pediatric ICU was 23 (15.33%) patients.

Conclusion

This study has shown that the frequency of pediatric acute respiratory distress syndrome is quite high.

Appraisal of the 'penumbra effect' using lingual pulse oximetry in anaesthetized dogs and cats

OBJECTIVE

Factors described as contributors to the 'penumbra effect' in relation to pulse oximetry include optical shunting, circulatory anastomoses and probe parallelity. This study aimed to clarify the main underlying mechanism involved.

STUDY DESIGN

Prospective clinical trial.

ANIMALS

A total of 30 dogs and 15 cats (client-owned).

METHODS

In anaesthetized dogs and cats, a pulse oximeter probe was placed on the tongue to measure haemoglobin oxygen saturation (SpO₂) and perfusion index. In 15 dogs, the probe was positioned at the root (baseline) of the tongue, then at 0.5 and 1 cm rostral to it, to investigate the effect of circulatory anastomoses on SpO₂ values. In cats (which do not have lingual arteriovenous anastomoses), the probe was positioned at the root and apex of the tongue. To assess the effect of probe parallelity on SpO₂ values in dogs, two lines were drawn parallel to the planes of the light-emitting diode and the detector surfaces and the intersection angle calculated using ImageMeter Pro, Google Play. In a further 15 dogs, the probe was placed at the tongue edge (0% optical shunt), with 50% optical shunt, then with the 50% optical shunt shielded. Data were analysed using Friedman's test, Student t test and Pearson's correlation coefficient (p < 0.05).

RESULTS

In dogs, SpO₂ values were significantly higher at 1.0 cm than at baseline (p < 0.0001). In cats, there were no significant differences in SpO₂ values at each location. There was no significant difference in SpO₂ between 0% and 50% optical shunt in dogs. SpO₂ had a moderate negative correlation with tongue thickness and negligible correlation with intersection angle.

CONCLUSIONS AND CLINICAL RELEVANCE

Circulatory anastomoses are probably responsible for observed changes in SpO₂ as the probe is placed towards an extremity, rather than optical shunting or probe parallelity.

Usability Testing of a Reusable Pulse Oximeter Probe Developed for Health-Care Workers Caring for Children < 5 Years Old in Low-Resource Settings

Hypoxemia measured by pulse oximetry predicts child pneumonia mortality in low-resource settings (LRS). Existing pediatric oximeter probes are prohibitively expensive and/or difficult to use, limiting LRS implementation. Using a human-centered design, we developed a low-cost, reusable pediatric oximeter probe for LRS health-care workers (HCWs). Here, we report probe usability testing. Fifty-one HCWs from Malawi, Bangladesh, and the United Kingdom participated, and seven experts provided reference measurements. Health-care workers and experts measured the peripheral arterial oxyhemoglobin saturation (SpO₂) independently in < 5 year olds. Health-care worker measurements were classed as successful if recorded in 5 minutes (or shorter) and physiologically appropriate for the child, using expert measurements as the reference. All expert measurements were considered successful if obtained in < 5 minutes. We analyzed the proportion of successful SpO₂ measurements obtained in < 1, < 2, and < 5 minutes and used multivariable logistic regression to predict < 1 minute successful measurements. We conducted four testing rounds with probe modifications between rounds, and obtained 1,307 SpO₂ readings. Overall, 67% (876) of measurements were successful and achieved in < 1 minute, 81% (1,059) < 2 minutes, and 90% (1,181) < 5 minutes. Compared with neonates, increasing age (infant adjusted odds ratio [aOR]; 1.87, 95% confidence interval [CI]: 1.16, 3.02; toddler aOR: 4.33, 95% CI: 2.36, 7.97; child aOR; 3.90, 95% CI: 1.73, 8.81) and being asleep versus being calm (aOR; 3.53, 95% CI: 1.89, 6.58), were associated with < 1 minute successful measurements. In conclusion, we designed a novel, reusable pediatric oximetry probe that was effectively used by LRS HCWs on children. This probe may be suitable for LRS implementation.

Physiologically driven, altitude-adaptive model for the interpretation of pediatric oxygen saturation at altitudes above 2,000 m a.s.l

Measuring peripheral oxygen saturation (SpO2) with pulse oximeters at the point of care is widely established. However, since SpO2 is dependent on ambient atmospheric pressure, the distribution of SpO2 values in populations living above 2000 m a.s.l. is largely unknown. Here, we propose and evaluate a computer model to predict SpO2 values for pediatric permanent residents living between 0 and 4,000 m a.s.l. Based on a sensitivity analysis of oxygen transport parameters, we created an altitude-adaptive SpO2 model that takes physiological adaptation of permanent residents into account. From this model, we derived an altitude-adaptive abnormal SpO2 threshold using patient parameters from literature. We compared the obtained model and threshold against a previously proposed threshold derived statistically from data and two empirical data sets independently recorded from Peruvian children living at altitudes up to 4,100 m a.s.l. Our model followed the trends of empirical data, with the empirical data having a narrower healthy SpO2 range below 2,000 m a.s.l. but the medians never differed more than 2.3% across all altitudes. Our threshold estimated abnormal SpO2 in only 17 out of 5,981 (0.3%) healthy recordings, whereas the statistical threshold returned 95 (1.6%) recordings outside the healthy range. The strength of our parametrized model is that it is rooted in physiology-derived equations and enables customization. Furthermore, as it provides a reference SpO2, it could assist practitioners in interpreting SpO2 values for diagnosis, prognosis, and oxygen administration at higher altitudes.NEW & NOTEWORTHY Our model describes the altitude-dependent decrease of SpO2 in healthy pediatric residents based on physiological equations and can be adapted based on measureable clinical parameters. The proposed altitude-specific abnormal SpO2 threshold might be more appropriate than rigid guidelines for administering oxygen that currently are only available for patients at sea level. We see this as a starting point to discuss and adapt oxygen administration guidelines.

Regional tissue oxygenation monitoring in the neonatal intensive care unit: evidence for clinical strategies and future directions

Near-infrared spectroscopy (NIRS)-based monitoring of regional tissue oxygenation (rSO₂) is becoming more commonplace in the neonatal intensive care unit (NICU). While increasing evidence supports rSO₂ monitoring, actual standards for applying this noninvasive bedside technique continue to evolve. This review highlights the current strengths and pitfalls surrounding practical NIRS-based monitoring in the neonatal population. The physiologic background of rSO₂ monitoring is discussed, with attention to understanding oxygen delivery/consumption mismatch and its effects on tissue oxygen extraction. The bedside utility of both cerebral and peripheral rSO₂ monitoring in the NICU is then explored from two perspectives: (1) disease/event-specific "responsive" monitoring and (2) "routine," continuous monitoring. Recent evidence incorporating both monitoring approaches is summarized with emphasis on practical applicability in the NICU. Finally, a future paradigm for a broad-based NIRS monitoring strategy is presented, with attention towards improving personalization of neonatal care and ultimately enhancing long-term outcomes.

Partially Wireless Pulse Oximetry Reduces Loss of Signal Integrity due to Motion in Children

OBJECTIVES

Continuous pulse oximetry monitoring is routine in many pediatric inpatient units, generating hundreds of alarms per patient per day, up to 90% of which are false (nonactionable). We hypothesized that continuously monitoring pulse oximetry with a partially wireless monitor without physical connection to a wall unit (wireless pox) will decrease episodes of loss of signal integrity (LOSI) generated by motion artifact in healthy pediatric subjects completing age-appropriate activities compared with a traditional wall-connected pulse oximeter (control pox), thereby reducing false alarms.

METHODS

Thirty-six healthy children, aged 1 to 17 years, were continuously monitored simultaneously with a wireless pox and a control pox while performing increasing levels of activity for 20 minutes. Continuous pulse oximetry data were recorded in 2 second intervals. Data were analyzed for LOSI. The Wilcoxon signed rank test was then used to compare the control pox to the wireless pox.

RESULTS

The wireless pox had fewer mean number of alarms due to LOSI (control 7.86, wireless 4.17, P = .0031) and fewer mean episodes of LOSI not leading to alarms (control 9.94, wireless 6.92, P = .0006). The control pox had a longer percent time in alarm state related to LOSI in all age groups.

CONCLUSIONS

This prospective observational study found that the wireless pox has decreased number and duration of events of LOSI compared with the control pox in healthy children. Implementation of partially wireless pulse oximetry in pediatric inpatient units may decrease episodes of LOSI and false alarms from motion artifact.

Accuracy of a portable pulse oximeter in monitoring hypoxemic infants with cyanotic heart disease

OBJECTIVE

Infants with single ventricle physiology have arterial oxygen saturations between 75 and 85%. Home monitoring with daily pulse oximetry is associated with improved interstage survival. They are typically sent home with expensive, bulky, hospital-grade pulse oximeters. This study evaluates the accuracy of both the currently used Masimo LNCS and a relatively inexpensive, portable, and equipped with Bluetooth technology study device, by comparing with the gold standard co-oximeter.

DESIGN

Prospective, observational study.

SETTING

Single institution, paediatric cardiac critical care unit, and neonatal ICU.

INTERVENTIONS

none.

PATIENTS

Twenty-four infants under 12 months of age with baseline oxygen saturation less than 90% due to cyanotic CHD.

MEASUREMENTS AND RESULTS

Pulse oximetry with WristOx2 3150 with infant sensors 8008 J (study device) and Masimo LCNS saturation sensor connected to a Philips monitor (hospital device) were measured simultaneously and compared to arterial oxy-haemoglobin saturation measured by co-oximetry. Statistical analysis evaluated the performances of each and compared to co-oximetry with Schuirmann's TOST equivalence tests, with equivalence defined as an absolute difference of 5% saturation or less. Neither the study nor the hospital device met the predefined standard for equivalence when compared with co-oximetry. The study device reading was on average 4.0% higher than the co-oximeter, failing to show statistical equivalence (p = 0.16). The hospital device was 7.4% higher than the co-oximeter and also did not meet the predefined standard for equivalence (p = 0.97).

CONCLUSION

Both devices tended to overestimate oxygen saturation in this patient population when compared to the gold standard, co-oximetry. The study device is at least as accurate as the hospital device and offers the advantage of being more portable with Bluetooth technology that allows reliable, efficient data transmission. Currently FDA-approved, smaller portable pulse oximeters can be considered for use in home monitoring programmes.

Oxygen saturations and neurodevelopmental outcomes in single ventricle heart disease

OBJECTIVES

To evaluate whether the degree of hypoxemia following stage-I and stage-II palliative surgeries predicts neurodevelopmental outcomes at 14 months of age in children with single ventricle congenital heart disease (SVCHD).

DESIGN

We analyzed longitudinal data from two Pediatric Heart Network (PHN) randomized controlled trials, with a total of 328 subjects. Oxygen saturations, measured via pulse oximetry, at time of discharge from stage-I and stage-II surgeries were the primary predictors of interest, and Bayley Scales of Infant Development-II (BSID-II) scores at 14 months old were the primary outcome measure. Relevant covariates from previously-published PHN studies were also included in regression models.

RESULTS

Oxygen saturations at time of discharge from stage-I and stage-II surgeries were not related to BSID-II scores. Having one or more oxygen saturation measurements below 80% was also not associated with BSID-II scores, and neither was change in oxygen saturations over time. These relationships were not altered by inclusion of relevant covariates.

CONCLUSIONS

In this large cohort of children with SVCHD, oxygen saturations post-stage-I and post-stage-II palliation surgeries as measured via pulse oximetry were not associated with neurodevelopmental outcomes at 14 months of age. The relationship between oxygen saturations and neurodevelopment in SVCHD is likely complex, and neurodevelopment is known to be affected by a number of factors. Pulse oximetry may also be an insufficient proxy for cerebral oxygen delivery. Clinically, pulse oximetry readings during the interstage and post-stage-II surgery periods are not a reliable predictor of future neurodevelopmental risk.

An Ultrasound-Based Biomedical System for Continuous Cardiopulmonary Monitoring: A Single Sensor for Multiple Information

Biomedical wearable sensors enable long-term monitoring applications and provide instantaneous diagnostic capabilities. Physiological monitoring can help in both the diagnosis and the ongoing treatment of a vast number of cardiovascular and pulmonary diseases such as hypertension, dysrhythmia, and asthma. In this paper, we present a system capable of monitoring several vital signals and physiological variables that determine the cardiopulmonary activity status. We explore direct measurements of multiple vital parameters with only one sensor and without special constraints. The system employs a PZT-4 piezo transducer stimulated by a suitable analog front end. The system both generates pulsed ultrasound waves at 1 MHz and amplifies reflected echoes to track internal organ motions, mainly that of the heart apex. According to the respiratory motion of the heart, the proposed system provides respiratory and heart cycles information. Promising results were obtained from six subjects with an average accuracy of 96.7% in heartbeats per minute measurement, referenced to a commercial photoplethysmography sensor. It also exhibits 94.5% sensitivity and 94.0% specificity in respiration detection compared to a spirometer signal as a reference.

Using machine learning models to predict oxygen saturation following ventilator support adjustment in critically ill children: A single center pilot study

BACKGROUND

In an intensive care units, experts in mechanical ventilation are not continuously at patient's bedside to adjust ventilation settings and to analyze the impact of these adjustments on gas exchange. The development of clinical decision support systems analyzing patients' data in real time offers an opportunity to fill this gap.

OBJECTIVE

The objective of this study was to determine whether a machine learning predictive model could be trained on a set of clinical data and used to predict transcutaneous hemoglobin oxygen saturation 5 min (5min SpO2) after a ventilator setting change.

DATA SOURCES

Data of mechanically ventilated children admitted between May 2015 and April 2017 were included and extracted from a high-resolution research database. More than 776,727 data rows were obtained from 610 patients, discretized into 3 class labels (< 84%, 85% to 91% and c92% to 100%).

PERFORMANCE METRICS OF PREDICTIVE MODELS

Due to data imbalance, four different data balancing processes were applied. Then, two machine learning models (artificial neural network and Bootstrap aggregation of complex decision trees) were trained and tested on these four different balanced datasets. The best model predicted SpO2 with area under the curves < 0.75.

CONCLUSION

This single center pilot study using machine learning predictive model resulted in an algorithm with poor accuracy. The comparison of machine learning models showed that bagged complex trees was a promising approach. However, there is a need to improve these models before incorporating them into a clinical decision support systems. One potentially solution for improving predictive model, would be to increase the amount of data available to limit over-fitting that is potentially one of the cause for poor classification performances for 2 of the three class labels.

Effect of Glittered Nail Polish on Pulse Oximetry Measurements in Healthy Subjects

Background:

Pulse oximeter is a simple and noninvasive standard device to monitor the saturation of peripheral oxygen (SpO₂) and heart rate. The nail polish of different colors may result in inaccurate oximetry reading and interpretation of oxygen saturation. This study aimed at determining the effect of different colors of glittered nail polish on SpO₂ in healthy students.

Materials and Methods:

This is a randomized clinical trial on 30 healthy students with SpO₂ ≥95% and without any complications on nail beds and environmental perfusion. SpO₂ was measured on 10 fingers of the participants after sitting and resting on a seat for 10 min in a room with normal temperature. Then they were asked to apply 10 colors of glittered nail polish randomly to their fingernails as all colors were used. After drying the two-layer nail polish, SpO₂ was measured again.

Results:

Of 10 glittered nail-polishes, dark green and purple did not change SpO₂ reading significantly. All other colors lowered SpO₂ significantly based on Wilcoxon test (red: p = 0.003; orange: p = 0.002; yellow: p = 0.015; pink: p = 0.017; dark blue: p = 0.001; violet: p = 0.001; brown: p = 0.001; black: p = 0.001). However, those changes were not clinically significant because SpO₂ differences before and after nail polish were in acceptable range (less than a 2% change).

Conclusions:

We conclude that different colors of glittered nail polishes do not result in a clinically significant change in pulse oximetry measurements in healthy subjects; therefore, it is not necessary to remove the glittered nail polish routinely in clinical, surgical, and emergency settings.

Retinal oximetry and systemic arterial oxygen levels

PURPOSE

Continuous peripheral pulse oximetry for monitoring adequacy of oxygenation is probably the most important technological advance for patients' monitoring and safety in the last decades. Pulse oximetry has the disadvantage of measuring the peripheral circulation, and the only mean to measure oxygen content of the central circulation is by invasive technology. Determination of blood oxyhaemoglobin saturation in the retinal vessels of the eye can be achieved noninvasively through spectrophotometric retinal oximetry which provides access to the central nervous system circulation. The aim of the thesis was to determine whether retinal oximetry technique can be applied for estimation of the central nervous system circulation which until now has only been possible invasively. This was achieved by measuring oxyhaemoglobin saturation in three adult subject study groups: in people with central retinal vein occlusion (CRVO) to observe local tissue hypoxia, in patients with severe chronic obstructive pulmonary disease (COPD) on long-term oxygen therapy to observe systemic hypoxaemia and in healthy subjects during hyperoxic breathing to observe systemic hyperoxemia. In addition, the fourth study that is mentioned was performed to test whether retinal oximetry is feasible for neonates.

METHODS

Retinal oximetry in central retinal vein occlusion: Sixteen subjects with central retinal vein occlusion participated in the study. The oxyhaemoglobin saturation of the central retinal vein occlusion affected eye was compared with the fellow unaffected eye. Retinal oximetry in healthy people under hyperoxia: Thirty healthy subjects participated in the study, and the oxyhaemoglobin saturation of retinal arterioles and venules was compared between normoxic and hyperoxic breathing. Retinal oximetry in severe chronic obstructive pulmonary disease: Eleven patients with severe chronic obstructive pulmonary disease participated in the study. Retinal oximetry measurements were made with and without their daily supplemental oxygen therapy. Retinal arteriolar oxyhaemoglobin saturation when inspiring ambient air was compared with blood samples from the radial artery and finger pulse oximetry and healthy controls. The healthy control group was assembled from our database for comparison of oxyhaemoglobin saturation of retinal arterioles and venules during the ambient air breathing. The retinal oximeter is based on a conventional fundus camera and a specialized software. A beam splitter coupled with two high-resolution digital cameras allows for simultaneous acquisition of retinal images at separative wavelengths for calculation of oxyhaemoglobin saturation. In addition, retinal images of 28 full-term healthy neonates were obtained with scanning laser ophthalmoscope combined with modified Oxymap analysis software for calculation of the optical density ratio and vessel diameter RESULTS: Retinal oximetry in central retinal vein occlusion: Mean retinal venous oxyhaemoglobin saturation was 31 ± 12% in CRVO eyes and 52 ± 11% in unaffected fellow eyes (mean ± SD, n = 14, p < 0.0001). The arteriovenous oxygen difference (AV-difference) was 63 ± 11% in CRVO eyes and 43 ± 7% in fellow eyes (p < 0.0001). The variability of retinal venous oxyhaemoglobin saturation was considerable within and between eyes affected by CRVO. There was no difference in oxyhaemoglobin saturation of retinal arterioles between the CRVO eyes and the unaffected eyes (p = 0.49). Retinal oximetry in healthy people under hyperoxia: During hyperoxic breathing, the oxyhaemoglobin saturation in retinal arterioles increased to 94.5 ± 3.8% as compared with 92.0 ± 3.7% at baseline (n = 30, p < 0.0001). In venules, the mean oxyhaemoglobin saturation increased to 76.2 ± 8.0% from 51.3 ± 5.6% (p < 0.0001) at baseline. The AV-difference was markedly lower during hyperoxic breathing as compared with the normoxic breathing (18.3 ± 9.0% versus 40.7 ± 5.7%, p < 0.0001). Retinal oximetry in severe chronic obstructive pulmonary disease: During ambient air breathing, chronic obstructive pulmonary disease subjects had significantly lower oxyhaemoglobin saturation than healthy controls in both retinal arterioles (87.2 ± 4.9% versus 93.4 ± 4.3%, p = 0.02, n = 11) and venules (45.0 ± 10.3% versus 55.2 ± 5.5%, p = 0.01) but the AV-difference was not markedly different (p = 0.17). Administration of their prescribed oxygen therapy significantly increased the oxyhaemoglobin saturation in retinal arterioles (87.2 ± 4.9% to 89.5 ± 6.0%, p = 0.02) but not in venules (45.0 ± 10.3% to 46.7 ± 12.8%, p = 0.3). Retinal oximetry values were slightly lower than finger pulse oximetry (mean percentage points difference = -3.1 ± 5.5) and radial artery blood values (-5.0 ± 5.4). Retinal oximetry study in neonates: The modified version of the retinal oximetry instrument estimated the optical density ratio in retinal arterioles to be 0.256 ± 0.041 that was significantly different from the 0.421 ± 0.089 in venules (n = 28, p < 0.001, paired t-test). The vascular diameter of retinal arterioles was markedly narrower than of venules (14.1 ± 2.7 and 19.7 ± 3.7 pixels, p < 0.001).

CONCLUSION

The results of this thesis indicate that spectrophotometric retinal oximetry is sensitive to both local and systemic changes in oxyhaemoglobin saturation. Retinal oxyhaemoglobin saturation values are slightly lower than radial artery blood sample and finger pulse oximetry values. The discrepancies between the different modalities are expected to derive from countercurrent exchange between central retinal artery and vein within the optic nerve but calibration issues cannot be excluded as contributing to this difference. Despite these differences, the findings indicate the potential of retinal oximetry for noninvasive real-time measurements of oxyhaemoglobin saturation in central nervous system vessels. Following calibration upgrade and technological improvement, verification retinal oximetry may potentially be applied to critically ill and anaesthesia care patients. The study on combined scanning laser ophthalmoscope and retinal oximetry supports the feasibility of the technique for oximetry analysis in newly born babies.

Pulse Oximetry with Two Infrared Wavelengths without Calibration in Extracted Arterial Blood

Oxygen saturation in arterial blood (SaO₂) provides information about the performance of the respiratory system. Non-invasive measurement of SaO₂ by commercial pulse oximeters (SpO₂) make use of photoplethysmographic pulses in the red and infrared regions and utilizes the different spectra of light absorption by oxygenated and de-oxygenated hemoglobin. Because light scattering and optical path-lengths differ between the two wavelengths, commercial pulse oximeters require empirical calibration which is based on SaO₂ measurement in extracted arterial blood. They are still prone to error, because the path-lengths difference between the two wavelengths varies among different subjects. We have developed modified pulse oximetry, which makes use of two nearby infrared wavelengths that have relatively similar scattering constants and path-lengths and does not require an invasive calibration step. In measurements performed on adults during breath holding, the two-infrared pulse oximeter and a commercial pulse oximeter showed similar changes in SpO₂. The two pulse oximeters showed similar accuracy when compared to SaO₂ measurement in extracted arterial blood (the gold standard) performed in intensive care units on newborns and children with an arterial line. Errors in SpO₂ because of variability in path-lengths difference between the two wavelengths are expected to be smaller in the two-infrared pulse oximeter.

Ultrasound Sensors for Diaphragm Motion Tracking: An Application in Non-Invasive Respiratory Monitoring

This paper introduces a novel respiratory detection system based on diaphragm wall motion tracking using an embedded ultrasound sensory system. We assess the utility and accuracy of this method in evaluating the function of the diaphragm and its contribution to respiratory workload. The developed system is able to monitor the diaphragm wall activity when the sensor is placed in the zone of apposition (ZOA). This system allows for direct measurements with only one ultrasound PZT5 piezo transducer. The system generates pulsed ultrasound waves at 2.2 MHz and amplifies reflected echoes. An added benefit of this system is that due to its design, the respiratory signal is less subject to motion artefacts. Promising results were obtained from six subjects performing six tests per subject with an average respiration detection sensitivity and specificity of 84% and 93%, respectively. Measurements were compared to a gold standard commercial spirometer. In this study, we also compared our measurements to other conventional methods such as inertial and photoplethysmography (PPG) sensors.