Is pulse oximetry helpful for the early detection of critical congenital heart disease at high altitude?

Trajectories of oxygen saturation within 6-72 hours after birth in neonates at moderate altitude: a prospective longitudinal cohort study

BACKGROUND

Trajectories of pulse oxygen saturation (SpO2) within the first few days after birth are important to inform the strategy for identifying asymptomatic hypoxemic disease but remain poorly substantiated at higher altitudes.

METHODS

We performed a longitudinal cohort study with consecutive neonates at a local hospital in Luchun County, China, at an altitude of 1650 m between January and July 2020. We repeatedly measured the pre- and post-ductal SpO2 values at 6, 12, 18, 24, 36, 48, and 72 hours after birth for neonates without oxygen supplements. All neonates underwent echocardiography and were followed up to 42 days after discharge. We included neonates without hypoxemic diseases to characterize the trajectories of SpO2 over time using a linear mixed model. We considered the 2.5th percentile as the reference value to define hypoxemic conditions.

RESULTS

A total of 1061 neonates were enrolled. Twenty-five had non-cardiac hypoxemic diseases, with 84% (21/25) presenting with abnormal SpO2 within 24 hours. One had tetralogy of Fallot identified by echocardiography. Among the 1035 asymptomatic neonates, SpO2 values declined from 6 hours after birth, reached a nadir at 48 hours, and tended to level off thereafter, with identical patterns for both pre- and post-ductal SpO2. The reference percentile was 92% for both pre- and post-ductal SpO2 and was time independent.

CONCLUSIONS

A decline within 48 hours features SpO2 trajectories within the first 72 hours at moderate altitude. Our findings suggest that earlier screening may favorably achieve a benefit-risk balance in identifying asymptomatic hypoxemic diseases in this population.

Establishing the reference interval for pulse oxygen saturation in neonates at high altitudes: protocol for a multicentre, open, cross-sectional study

INTRODUCTION

Establishing the reference interval for pulse oxygen saturation (SpO₂) is essential for sensitively identifying neonatal hypoxaemia due to various causes. However, the reference interval for high altitudes has not yet been established, and existing studies have many limitations. This study will aim to establish the reference interval for various high altitudes and determine whether preductal and postductal measurements at the same altitude vary.

METHODS AND ANALYSIS

This is a multicentre, open, cross-sectional study, which will begin in February 2022. Approximately 2000 healthy full-term singleton neonates will be recruited from six hospitals (altitude ≥2000 m) in Qinghai Province, China. The participating hospitals will use a uniform pulse oximeter type. The measurements will be performed between 24 hours after birth and discharge. During the measurement, the neonate will be awake and quiet. Preductal and postductal measurements will be performed. The measurement time, site and results will be recorded and input, along with the collected basic information, into the perinatal cloud database. We will carry out strict quality control for basic information collection, measurement and data filing. We will perform descriptive statistics on the distribution range of the collected data, determine the lower limit value of the reference interval for each hospital and the corresponding altitude, perform curve fitting for the lower limit value, use the altitude as a covariate for the function corresponding to the fitted curve, establish the prediction equation and ultimately determine the reference intervals of each high altitude location.

ETHICS AND DISSEMINATION

Our protocol has been approved by the Medical Ethics Committee of all participating hospitals. We will publish our study results in academic conferences and peer-reviewed public journals.

TRIAL REGISTRATION NUMBER

NCT05115721.

Respiratory physiology at high altitude and considerations for pediatric patients

Over 150 million people, including many children, live at high altitude (>2500 m) with the majority residing in Asia and South America. With increases in elevation, the partial pressure of oxygen (pO2) is reduced, resulting in a hypobaric hypoxic environment. Fortunately, humans have evolved adaptive processes which serve to acclimate the body to such conditions. These mechanisms, occurring along a specific time course, result in tachypnea, tachycardia, diuresis, and hematopoiesis, and a shift in the oxygen dissociation curve favoring an increased affinity for oxygen. These, along with other physiological effects, including increased pulmonary vascular resistance, alterations in cerebral blood flow, and changes in sensitivity to opioids, must be considered when administering anesthesia at high altitudes. Susceptible individuals or those who ascend too quickly may outpace the body's ability to acclimate resulting in one or more forms of high-altitude sickness ranging from the milder acute mountain sickness to the more serious conditions of high-altitude pulmonary edema and cerebral edema, either of which can be life-threatening if not promptly recognized and treated. Since the adaptive mechanisms for acclimatization greatly affect the cardiopulmonary systems, patients with underlying health issues such as sleep apnea, congenital heart disease, and asthma may have susceptibilities and warrant special consideration. Clinicians should have an understanding of the physiologic adaptations, anesthetic considerations, and special concerns in these populations in order to offer the best care possible.

Oxygen Saturation Behavior by Pulse Oximetry in Female Athletes: Breaking Myths

The myths surrounding women’s participation in sport have been reflected in respiratory physiology. This study aims to demonstrate that continuous monitoring of blood oxygen saturation during a maximal exercise test in female athletes is highly correlated with the determination of the second ventilatory threshold (VT2) or anaerobic threshold (AnT). The measurements were performed using a pulse oximeter during a maximum effort test on a treadmill on a population of 27 healthy female athletes. A common behavior of the oxygen saturation evolution during the incremental exercise test characterized by a decrease in saturation before the aerobic threshold (AeT) followed by a second significant drop was observed. Decreases in peripheral oxygen saturation during physical exertion have been related to the athlete’s physical fitness condition. However, this drop should not be a limiting factor in women’s physical performance. We found statistically significant correlations between the maximum oxygen uptake and the appearance of the ventilatory thresholds (VT1 and VT2), the desaturation time, the total test time, and between the desaturation time and the VT2. We observed a relationship between the desaturation time and the VT2 appearance. Indeed, a linear regression model between the desaturation time and the VT2 appearance can predict 80% of the values in our sample. Besides, we suggest that pulse oximetry is a simple, fairly accurate, and non-invasive technique for studying the physical condition of athletes who perform physical exertion.

Reference Interval for Pulse Oxygen Saturation in Neonates at Different Altitudes: A Systematic Review

Introduction: The reference interval for pulse oxygen saturation (SpO₂) in neonates born at high altitudes has not been defined to date. The purpose of this study was to systematically review published studies and determine the reference interval of SpO₂ in neonates at different altitudes. Methods: Databases of PubMed, Embase, Cochrane Library, Clinicaltrials.Gov, Chinese National Knowledge Infrastructure Database, Wanfang Database, Chinese Science Technology Journals Database, and Chinese Clinical Trial Registry were searched for studies reporting SpO₂ in healthy neonates at different altitudes. Retrieval time was from inception of the database to August 16, 2021. The Agency for Healthcare Research and Quality checklist was used to evaluate the quality of studies. Python v3.8 was used to analyze the data. This systematic review was drafted in accordance with the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Results: Seven cross-sectional studies, published between 1991 and 2020, were identified. They were from US, Mexico, Israel, Ecuador, and China. Three studies were rated as high quality and four as moderate quality. The mean SpO₂ (with standard deviation or standard error) of neonates born in 40 different altitudes (ranging from 25 meters to 3,100 meters) were obtained. The prediction equation for calculation of the lower limit of the reference interval was established, and the reference intervals for SpO₂ at different altitudes were determined. Conclusions: In healthy neonates, the lower limit of the reference interval of SpO₂ decreases with increase in altitude. High-quality prospective studies are need to confirm our findings.

Pulse oximetry screening for detection of congenital heart defects at 1646 m in Albuquerque, New Mexico

AIM

To determine the false-positive rate of pulse oximetry screening at moderate altitude, presumed to be elevated compared with sea level values and assess change in false-positive rate with time.

METHODS

We retrospectively analysed 3548 infants in the newborn nursery in Albuquerque, New Mexico, (elevation 5400 ft) from July 2012 to October 2013. Universal pulse oximetry screening guidelines were employed after 24 hours of life but before discharge. Newborn babies between 36 and 36 6/7 weeks of gestation, weighing >2 kg and babies >37 weeks weighing >1.7 kg were included in the study. Log-binomial regression was used to assess change in the probability of false positives over time.

RESULTS

Of the 3548 patients analysed, there was one true positive with a posteriorly-malaligned ventricular septal defect and an interrupted aortic arch. Of the 93 false positives, the mean pre- and post-ductal saturations were lower, 92 and 90%, respectively. The false-positive rate before April 2013 was 3.5% and after April 2013, decreased to 1.5%. There was a significant decrease in false-positive rate (p = 0.003, slope coefficient = -0.082, standard error of coefficient = 0.023) with the relative risk of a false positive decreasing at 0.92 (95% CI 0.88-0.97) per month.

CONCLUSION

This is the first study in Albuquerque, New Mexico, reporting a high false-positive rate of 1.5% at moderate altitude at the end of the study in comparison to the false-positive rate of 0.035% at sea level. Implementation of the nationally recommended universal pulse oximetry screening was associated with a high false-positive rate in the initial period, thought to be from the combination of both learning curve and altitude. After the initial decline, it remained steadily elevated above sea level, indicating the dominant effect of moderate altitude.

Clinical Spectrum of congenital heart defects (CHD) detected at the child health Clinic in a Tertiary Health Facility in Ghana: a retrospective analysis

Background

Congenital heart defects (CHD) are the singular most common congenital anomalies and account for a significant fraction of childhood mortality and morbidity. CHD occurs in ~ 1% of livebirths globally and often requires surgical interventions to improve quality of life and survival of patients. The prevalence and clinical presentations of CHD within specific populations provide a clearer overview of the burden of CHD and informs appropriate interventions. However, there is limited data on clinical presentation and occurrence of CHD in African countries such as Ghana where most cases are either diagnosed late or missed entirely resulting in increased mortality. In this retrospective study, we assessed the clinical presentations, associated comorbidities, and prescription patterns of diagnosed CHD in a tertiary facility in Ghana.

Method

This retrospective study utilized data from electronic health records (EHR) from the child health clinic of the Cape Coast Teaching Hospital - a tertiary health facility in Ghana from January 2018 to October 2019. All suspected or provisionally diagnosed cases including those confirmed with echocardiography were included in our analysis.

Results

Over 10, 000 records were reviewed, CHD was diagnosed in 79 cases, and 51 cases had complete clinical records including the type of CHD and clinical presentation. Male to female ratio was approximately 1:1 and 77.2% of the diagnoses were in children below 5 years. Acyanotic congenital heart defects were most commonly diagnosed with ventricular septal defects (VSD) and patent ductus arteriosus (PDA) being the simplest singular CHD. Tetralogy of Fallot, was the most common complex CHD accounting for 25.5% (13) of cases. Bronchopneumonia, upper respiratory infections and pneumonia were the most commonly diagnosed comorbidities accounting for over 35% of non-cardiac sequalae based on antibiotic and diuretic use.

Conclusion

Our study showed that over 75% of CHD cases were diagnosed under 5 years with VSD and TOF being the most commonly diagnosed acyanotic and cyanotic lesions, respectively. This study presents preliminary data that give an overview of CHD burden in Ghana that will inform future research and appropriate interventions.

Detección temprana de cardiopatías congénitas en neonatos sanos con oximetría de pulso

Introducción: Las cardiopatías congénitas son la principal causa de morbimortalidad cardiovascular en los neonatos, por ello, es necesario un diagnóstico temprano para iniciar un tratamiento adecuado. Objetivo: Evaluar la utilidad de la oximetría de pulso como método de tamizaje para su detección. Metodología: Se realizó un estudio analítico observacional de cohorte prospectivo en el que se usó la oximetría de pulso como método de tamizaje para enfermedad cardíaca a 376 recién nacidos. El algoritmo Americano de Tamizaje Cardíaco fue utilizado como fundamento para el estudio. Resultados: Se realizaron ecocardiogramas en los que se identificó un 90% de una cardiopatía congénita acianógena y el 10% fueron normales. Discusión: Se deseaba generar evidencia acerca de la detección temprana de cardiopatías congénitas con el uso de la oximetría de pulso en recién nacidos y se obtuvo resultados que favorecen su uso. Efectivamente en quienes obtuvieron un tamizaje positivo, el ecocardiograma evidenció una cardiopatía acianógena la mayoría de las veces.

High Altitude as a Cause of Congenital Heart Defects: A Medical Hypothesis Rediscovered in Ecuador

Background: There are ∼83 million people living at high altitude (>2500 m) worldwide who endure chronic hypoxia conditions. This article aims to analyze the relationship between high altitude, identified in several cities in Ecuador, and the prevalence of congenital heart disease (CHD). Methods: Set in Ecuador, this epidemiological observational cross-sectional study analyzes data over a range of 18 years (from 2000 to 2017), including 34,904 reported cases of CHD, with a mean of 1939 cases per year. Results: The mean prevalence rate of CHD found is 70.6 per 10,000 live newborns. A K-means analysis resulted in three clusters. Cluster 1 shows the lowest altitude and prevalence of CHD, with an average of 2619 m and 63.02 cases per 10,000 live newborns. Cluster 2 presents the second highest altitude and prevalence of CHD, with an average of 2909 m and 72.04 cases per 10,000 live newborns. Cluster 3 shows the highest values of altitude and prevalence of CHD, with an average of 3176 m and 86.62 cases per 10,000 live newborns. Pearson's coefficient is 0.979, so the correlation between the variables is positive. An altitude ranging from 2500 to 2750 m relates to a prevalence of CHD of ≤71 cases per 10,000 live newborns. An altitude ranging from 2751 to 3000 m relates to a prevalence of CHD of >71 and <89 cases per 10,000 live newborns. An altitude ranging between 3001 and 3264 m relates to a prevalence of CHD of ≥89 cases per 10,000 live newborns. Conclusions: The findings show that high altitude (>2500 m), ethnicity (Native American), rural locations, and limited access to health care are factors that influence and increase the prevalence rate of CHD. A correlation coefficient of 0.914 shows the direct relationship between high altitude and prevalence rates of CHD. For each year elapsed, the prevalence of CHD increased by 3.33 cases per 10,000 live newborns.