Daytime SpO2 Research Articles

The impact of obstructive sleep apnea in children with sickle cell disease and asthma.

Asthma and obstructive sleep apnea (OSA) are chronic diseases that disproportionately affect children with sickle cell disease (SCD). The literature describes the negative impact that both conditions have on children with SCD separately; however, the effect of OSA on asthmatic children with OSA is less specific. We hypothesized that the presence of OSA in children with SCD and asthma is associated with specific hematologic markers, worse clinical outcomes, and greater healthcare utilization. We retrospectively evaluated children with both SCD and asthma who underwent polysomnography (PSG). We assessed their demographic information, PSG data, hematologic indices, and healthcare utilization based on the concurrent presence of OSA. Fifty-nine percent of the cohort had OSA with a lower oxygen saturation (SpO2 ) nadir (87% vs. 93%, p < 0.001) and a lower median daytime SpO2 (96.5% vs. 98.5%, p < 0.05); those with OSA were more likely to have the hemoglobin SS genotype (86% vs. 46.5%, p = 0.03). Additionally, those with OSA had a higher mean corpuscular volume (87 vs. 77.2 fL, p = 0.03) and reticulocyte count (10.1% vs. 5.5%, p < 0.01). There was no difference in asthma severity or healthcare utilization between those with OSA and those without OSA. Overall, children with SCD and asthma might be at increased risk for developing OSA, and screening for sleep-disordered breathing should be incorporated as part of their routine care.

Pulse oximetry values from 33,080 participants in the Apple Heart & Movement Study

Wearable devices that include pulse oximetry (SpO2) sensing afford the opportunity to capture oxygen saturation measurements from large cohorts under naturalistic conditions. We report here a cross-sectional analysis of 72 million SpO2 values collected from 33,080 individual participants in the Apple Heart and Movement Study, stratified by age, sex, body mass index (BMI), home altitude, and other demographic variables. Measurements aggregated by hour of day into 24-h SpO2 profiles exhibit similar circadian patterns for all demographic groups, being approximately sinusoidal with nadir near midnight local time, zenith near noon local time, and mean 0.8% lower saturation during overnight hours. Using SpO2 measurements averaged for each subject into mean nocturnal and daytime SpO2 values, we employ multivariate ordinary least squares regression to quantify population-level trends according to demographic factors. For the full cohort, regression coefficients obtained from models fit to daytime SpO2 are in close quantitative agreement with the corresponding values from published reference models for awake arterial oxygen saturation measured under controlled laboratory conditions. Regression models stratified by sex reveal significantly different age- and BMI-dependent SpO2 trends for females compared with males, although constant terms and regression coefficients for altitude do not differ between sexes. Incorporating categorical variables encoding self-reported race/ethnicity into the full-cohort regression models identifies small but statistically significant differences in daytime SpO2 (largest coefficient corresponding to 0.13% lower SpO2, for Hispanic study participants compared to White participants), but no significant differences between groups for nocturnal SpO2. Additional stratified analysis comparing regression models fit independently to subjects in each race/ethnicity group is suggestive of small differences in age- and sex-dependent trends, but indicates no significant difference in constant terms between any race/ethnicity groups for either daytime or nocturnal SpO2. The large diverse study population and study design employing automated background SpO2 measurements spanning the full 24-h circadian cycle enables the establishment of healthy population reference trends outside of clinical settings.

Screening and treatment of pre-bariatric surgical patients with obesity related sleep disordered breathing.

There is a significant burden of sleep disordered breathing (SDB) in patients living with severe and complex obesity undergoing pre-bariatric surgery assessment. This longitudinal observational study evaluated the burden of obesity hypoventilation syndrome (OHS) in this cohort of patients and the therapeutic compliance of patients commenced on positive airway pressure treatment. All pre-bariatric surgery patients referred to the sleep clinic for review after an abnormal screening study between 2018 and 2022 were included. We collected data on their sleep study results, anthropometrics, co-morbid medical conditions, clinical observations, spirometry and arterial blood gas (ABG). Patients commenced on therapy were followed-up longitudinally and compliance data collected via remote monitoring. A total of 116 patients were included [age: mean ± standard deviation (SD) 48.8±10.8 years; body mass index (BMI) 49.2±8.5 kg/m2; Epworth Sleepiness Scale (ESS) 8.7±5.1 points]. Fifteen patients (12.9% of cohort) were diagnosed with hypercapnic respiratory failure (pH 7.40±0.02; pO2 11.00±1.04 kPa; pCO2 6.15±0.08 kPa). Compared to eucapnic obstructive sleep apnoea (OSA) patients, they were older (51.1 vs. 48.5 years; P=0.311), had a higher BMI (51.5 vs. 48.9 kg/m2; P=0.266), more likely to be female (66.7% vs. 53.5%; P=0.275) and had a higher ESS score (10.4 vs. 8.5 points; P=0.177). On binomial regression analysis insulin dependent diabetes was the only patient characteristic of significance with prevalence increased in patients with OHS (26.7% vs. 8.9%; P=0.042). Forced vital capacity (FVC) and oxygen saturation (SpO2) cut-offs demonstrated high specificity (96.8%) but low sensitivity (13.3%) to diagnosed hypercapnia. Fifty percent of the patients with hypercapnia required bi-level ventilation. On follow-up 44.9% of patients were compliant with therapy (>4 hours usage/night). In minimally symptomatic patients living with severe and complex obesity who have an abnormal overnight oximetry, over 1 in 10 demonstrated chronic respiratory failure. Clinic spirometry and daytime SpO2 excluded those with hypercapnia. Overall adherence to prescribed therapy is low. Screening, appropriate pre-operative optimisation and peri-operative planning are important in preventing complications in this patient cohort.

COPD sleep phenotypes: Genesis of respiratory failure in COPD.

The chronic obstructive pulmonary disease (COPD) patients could have respiratory failure during sleep without daytime overt arterial blood gas (ABG) abnormality. We undertook a study first of its kind to attempt in distinguishing the underlying pathophysiological mechanisms. It was a prospective observational study in stable COPD patients. The inclusion criterion was presence of day time PaO2>60 mmHg and PaCO2<45 mmHg. Twenty five out of 110 patients were excluded because of the ABG abnormality. The remaining 85 patients were subjected to overnight pulse oximetry and end-tidal (ET)-CO2 monitoring. The nocturnal oxygen desaturation was defined as per Fletcher's criteria. The nocturnal hypoventilation was defined as per American academy of sleep medicine (AASM) guidelines. Patients having saw-tooth pattern on pulse oximetry and/or snoring were subjected to polysomnography. 38/85(44.8%) patients had nocturnal gas exchange abnormality in absence of daytime respiratory failure and were identified into 3 different phenotypes: obstructive sleep apnoea (OSA), nocturnal hypoventilation and nocturnal oxygen desaturation. The isolated abnormality was seen in 24 patients: 10 patients had OSA, 9 had nocturnal hypoventilation and 5 had nocturnal oxygen desaturation. Overlap of two or more phenotypes was seen in 14 patients. As compared to the nocturnal hypoventilation and desaturation phenotypes, the OSA phenotype had a significantly higher BMI & FEV1. The nocturnal hypoventilation and the desaturation phenotypes did not have significant difference in FEV1 and BMI, but the daytime SpO2 and PaO2 differed significantly. Such parameters could help in identifying the three distinct COPD-sleep phenotypes (OSA, nocturnal hypoventilation and nocturnal oxygen desaturation). A phenotype based nocturnal management may help in delaying the process of overt respiratory failure in COPD.

Impact of 2 days of staging at 2500-4300m on sleep quality and quantity following subsequent exposure to 4300m.

The impact of 2 days of staging at 2500–4300 m on sleep quality and quantity following subsequent exposure to 4300 m was determined. Forty‐eight unacclimatized men and women were randomly assigned to stage for 2 days at one of four altitudes (2500, 3000, 3500, or 4300 m) prior to assessment on the summit of Pikes Peak (4300 m) for 2 days. Volunteers slept for one night at sea level (SL), two nights at respective staging altitudes, and two nights at Pikes Peak. Each wore a pulse oximeter to measure sleep arterial oxygen saturation (sSpO2, %) and number of desaturations (DeSHr, events/hr) and a wrist motion detector to estimate sleep awakenings (Awak, awakes/hr) and sleep efficiency (Eff, %). Acute mountain sickness (AMS) was assessed using the Environmental Symptoms Questionnaire and daytime SpO2 was assessed after AMS measurements. The mean of all variables for both staging days (STG) and Pikes Peak days (PP) was calculated. The sSpO2 and daytime SpO2 decreased (p < 0.05) from SL during STG in all groups in a dose‐dependent manner. During STG, DeSHr were higher (p < 0.05), Eff was lower (p < 0.05), and AMS symptoms were higher (p < 0.05) in the 3500 and 4300 m groups compared to the 2500 and 3000 m groups while Awak did not differ (p > 0.05) between groups. At PP, the sSpO2, DeSHr, Awak, and Eff were similar among all groups but the 2500 m group had greater AMS symptoms (p < 0.05) than the other groups. Two days of staging at 2500–4300 m induced a similar degree of sleep acclimatization during subsequent ascent to 4300 m but the 2500 m group was not protected against AMS at 4300 m.

Simple screening model for identifying the risk of sleep apnea in patients on opioids for chronic pain

BackgroundThere is an increased risk of sleep apnea in patients using opioids for chronic pain. We hypothesized that a simple model comprizing of: (1) STOP-Bang questionnaire and resting daytime oxyhemoglobin...

Sleep features in Lymphangioleiomyomatosis and their relationship with disease severity: a pilot study

Lymphangioleiomyomatosis (LAM) is a rare pulmonary disease characterized by progressive airflow limitation. We conducted a pilot trial to investigate the incidence of sleep disorders, sleep quality and their relationship with disease severity.We performed pulmonary function tests, blood gas analysis, overnight 12-channels polysomnography and clinical assessments in 15 consecutive LAM patients. For statistics, p values < 0.05 were considered significant.Sleep efficiency (SE) was inversely correlated with RV/TLC (p = 0.035) and positively with daytime SpO2 (p = 0.010) and PaO2 (p = 0.011). Three cases had obstructive sleep apnea (OSA); seven patients (46.7%) showed a REMOSA. AHIREM was correlated with FEV1% (r = 0.75, p = 0.003), TLC% (r = 0.57, p = 0.026), RV% (r = 0.8, p=<0.0001) and RV/TLC (r = 0.77, p = 0.001). No correlations were observed between anxiety/depression and SE, CAP rate, pulmonary function test variables and AHIREM (p > 0.05). four subjects had nocturnal hypoxia (T90 ≥ 1% of TST) showing lower values of DLCO%, daytime SpO2%, PaO2, FEV1% and a higher value of VR/TLC comparing with the subgroup with normal T90 (p < 0.05).This pilot study shows that sleep alterations could be frequent in LAM and associated to disease severity. Nocturnal hypoxemia and SE were related to lung function impairment. A dysregulation of sleep seems to involve exclusively REM phase, while NREM appears to be preserved. This phenomenon might be linked to the pathophysiology of disease: our study, even with the limits of the small sample size, showed that the presence of REMOSA is related to the disease severity, in particular to the degree of airflow limitation and hyperinflation. More studies are needed to assess this topic.

Relationships Between Chemoreflex Responses, Sleep Quality, and Hematocrit in Andean Men and Women.

Andean highlanders are challenged by chronic hypoxia and many exhibit elevated hematocrit (Hct) and blunted ventilation compared to other high-altitude populations. While many Andeans develop Chronic Mountain Sickness (CMS) and excessive erythrocytosis, Hct varies markedly within Andean men and women and may be driven by individual differences in ventilatory control and/or sleep events which exacerbate hypoxemia. To test this hypothesis, we quantified relationships between resting ventilation and ventilatory chemoreflexes, sleep desaturation, breathing disturbance, and Hct in Andean men and women. Ventilatory measures were made in 109 individuals (n = 63 men; n = 46 women), and sleep measures in 45 of these participants (n = 22 men; n = 23 women). In both men and women, high Hct was associated with low daytime SpO2 (p < 0.001 and p < 0.002, respectively) and decreased sleep SpO2 (mean, nadir, and time <80%; all p < 0.02). In men, high Hct was also associated with increased end-tidal PCO2 (p < 0.009). While ventilatory responses to hypoxia and hypercapnia did not predict Hct, decreased hypoxic ventilatory responses were associated with lower daytime SpO2 in men (p < 0.01) and women (p < 0.009) and with lower nadir sleep SpO2 in women (p < 0.02). Decreased ventilatory responses to CO2 were associated with more time below 80% SpO2 during sleep in men (p < 0.05). The obstructive apnea index and apnea-hypopnea index also predicted Hct and CMS scores in men after accounting for age, BMI, and SpO2 during sleep. Finally, heart rate response to hypoxia was lower in men with higher Hct (p < 0.0001). These data support the idea that hypoventilation and decreased ventilatory sensitivity to hypoxia are associated with decreased day time and nighttime SpO2 levels that may exacerbate the stimulus for erythropoiesis in Andean men and women. However, interventional and longitudinal studies are required to establish the causal relationships between these associations.

Higher oxygen saturation with hydroxyurea in paediatric sickle cell disease

IntroductionSickle cell disease (SCD) is one of the most common inherited diseases worldwide. It is associated with lifelong morbidity and reduced life expectancy. Hydroxyurea (HU) has been shown to reduce...

Predictive factors for sleep apnoea in patients on opioids for chronic pain

BackgroundThe risk of death is elevated in patients taking opioids for chronic non-cancer pain. Respiratory depression is the main cause of death due to opioids and sleep apnoea is an...

Wearable Finger Pulse Oximetry for Continuous Oxygen Saturation Measurements During Daily Home Routines of Patients With Chronic Obstructive Pulmonary Disease (COPD) Over One Week: Observational Study.

BackgroundChronic obstructive pulmonary disease (COPD) patients can suffer from low blood oxygen concentrations. Peripheral blood oxygen saturation (SpO2), as assessed by pulse oximetry, is commonly measured during the day using a spot check, or continuously during one or two nights to estimate nocturnal desaturation. Sampling at this frequency may overlook natural fluctuations in SpO2.ObjectiveThis study used wearable finger pulse oximeters to continuously measure SpO2 during daily home routines of COPD patients and assess natural SpO2 fluctuations.MethodsA total of 20 COPD patients wore a WristOx2 pulse oximeter for 1 week to collect continuous SpO2 measurements. A SenseWear Armband simultaneously collected actigraphy measurements to provide contextual information. SpO2 time series were preprocessed and data quality was assessed afterward. Mean SpO2, SpO2 SD, and cumulative time spent with SpO2 below 90% (CT90) were calculated for every (1) day, (2) day in rest, and (3) night to assess SpO2 fluctuations.ResultsA high percentage of valid SpO2 data (daytime: 93.27%; nocturnal: 99.31%) could be obtained during a 7-day monitoring period, except during moderate-to-vigorous physical activity (MVPA) (67.86%). Mean nocturnal SpO2 (89.9%, SD 3.4) was lower than mean daytime SpO2 in rest (92.1%, SD 2.9; P<.001). On average, SpO2 in rest ranged over 10.8% (SD 4.4) within one day. Highly varying CT90 values between different nights led to 50% (10/20) of the included patients changing categories between desaturator and nondesaturator over the course of 1 week.ConclusionsContinuous SpO2 measurements with wearable finger pulse oximeters identified significant SpO2 fluctuations between and within multiple days and nights of patients with COPD. Continuous SpO2 measurements during daily home routines of patients with COPD generally had high amounts of valid data, except for motion artifacts during MVPA. The identified fluctuations can have implications for telemonitoring applications that are based on daily SpO2 spot checks. CT90 values can vary greatly from night to night in patients with a nocturnal mean SpO2 around 90%, indicating that these patients cannot be consistently categorized as desaturators or nondesaturators. We recommend using wearable sensors for continuous SpO2 measurements over longer time periods to determine the clinical relevance of the identified SpO2 fluctuations.

Nocturnal Hypoxemia, a Key Parameter in Overlap Syndrome

The overlap syndrome (OS) is defined as a synergic relation between obstructive sleep apnea (OSA) and chronic obstructive pulmonary disease (COPD). Patients with overlap syndrome present the clinical features of each disorder to a greater or a lesser extend depending on the predominant disease. We assessed the main differences between patients with OS and patients with OSA and we highlight the importance of nocturnal hypoxemia on clinical status and management of the patients with overlap syndrome, in order to simplify OSA screening tests in patients with COPD. The study population included 62 selected patients divided in two groups: the first group � subjects diagnosed with OS and the second group - subjects with OSA, without the diagnostic of COPD. The majority of the patients were male, with a mean age of 55�9.84 years in the OSA group and 65.5�10.32 years in the OS group. The nocturnal hypoxemia was more important in the OS grup, with 276.83 minutes spent at a SpO2 below 90% versus 132.98 minutes in the OSA group. The mean AHI was 57.7�29.244 events/hour of sleep in the OS group and 50.7�26.01 events/hour of sleep in the OSA group. At the diagnosis, the mean daytime SpO2 was 90.9�3.59% in the OS group and 95.9�1.57 % in the OSA group. There were statistically significant differences between the two groups concerning age, AHI, Epworth Slepiness Scale, nocturnal desaturation, medium and minimum SpO2 during sleep, daytime SpO2 at the diagnosis and at 1-year follow-up, the presence of cardiovascular comorbidities such as pulmonary hypertension and heart failure. Our study showed that patients with COPD have OSA predictors that differ from those usually recognise in the general population. In OS patients, the most important parameter is the nocturnal hypoxemia. So, it is very useful that the clinicians be trained to include in the management of selected obese COPD patients, comprehensive sleep history, sleep hygiene and OSA screening because, in clinical practice, OSA is quite often underdiagnosed in these patients.

Predictors of obesity hypoventilation syndrome among patients with sleep-disordered breathing in India.

Introduction:No study has been done in India to evaluate obesity hypoventilation syndrome (OHS) among patients with sleep-disordered breathing (SDB). The known predictors of OHS, i.e., body mass index (BMI) >35 kg/m2 and forced vital capacity (FVC) <3.5 L for men and <2.3 L for women from western countries, cannot be applied to Indian patients.Objectives:To find out the prevalence of OHS and to determine the predictors of OHS among Indian SDB patients.Materials and Methods:It was a retrospective observational study conducted in a tertiary care institute from September 1, 2017, to August 31, 2018. All the patients who underwent polysomnography were analyzed for the presence of OHS. Of 85 patients referred for polysomnography, 76 had SDB. Thirteen patients were excluded because of hypoventilation due to other known causes or could not perform spirometry.Results:The prevalence of OHS among SDB after excluding the other causes of hypoventilation was 15.87% (10/63). The predictors were determined using univariate analysis between daytime partial pressure of carbon dioxide (PaCO2) and other predictors. PaCO2 significantly correlated with minimum nocturnal oxygen saturation by pulse oximetry (SpO2), FVC %predicted, BMI, daytime SpO2, forced expiratory volume %predicted, and partial pressure of oxygen (PaO2). Following a stepwise multiple regression, minimum nocturnal SpO2, FVC %predicted, and BMI were found to be independent predictors of OHS. A minimum nocturnal SpO2 threshold of 60%, FVC %predicted <74.5%, BMI >30.95 kg/m2, and absolute FVC <2.33 L for men and <1.68 L for women were found to be predictors of OHS.Conclusion:The prevalence of OHS in Indian patients is similar to Caucasians. OHS is seen in Indian patients even at a lower BMI and lower spirometric parameters.

Role of oxygen and continuous positive airway pressure therapy in chronic obstructive pulmonary disease patients with nocturnal oxygen desaturation

Sleep has a significant effect on respiration, even in healthy individuals. Breathing difficulties in chronic obstructive pulmonary disease (COPD) patients during sleep are one of the most common symptoms in these patients. Nocturnal desaturation may occur in COPD in the absence of severe daytime hypoxemia. Nocturnal desaturation may contribute to the development of pulmonary hypertension, nocturnal cardiac arrhythmias, and death during sleep. However, the optimal treatment for patients with isolated nocturnal hypoxemia remains uncertain. The aim of this study was to assess the role of oxygen and continuous positive airway pressure (CPAP) therapy in COPD patients with nocturnal oxygen desaturation (NOD). This study was conducted on 40 male COPD patients. The included patients were classified into two groups: group 1 included normoxic or mildly hypoxic patients with day time SpO2≥91% defined as NOD by fall of greater than 4% from awake SpO2, and group 2 included moderate and severely hypoxic patients with daytime SpO2≤90% who showed a pulse oximetric plot with at least 5 min with SpO2≤90% and a peak of SpO2≤85% and were considered as nocturnal desaturator. The two groups were subjected to full history taking, clinical examination, the Epworth sleepiness scale, anthropometric measurements, pulmonary function tests (spirometry), radiological examination using chest radiograph, and SpO2 using pulse oximetry. SpO2 evaluation using pulse oximetry was carried out for four nights: the first night while breathing room air, the second night while giving low-flow humidified oxygen (2 l/min) overnight, the third night with patients on noninvasive ventilation using autoset CPAP mask, and the fourth night with patients on noninvasive ventilation using autoset CPAP mask with low-flow humidified oxygen (2 l/min). The included patients had moderate, severe, and very severe COPD according to the GOLD spirometric classification. The highest mean value of oxygen saturation was seen in cases that received CPAP with oxygen, followed by cases that received low-flow humidified nasal oxygen, and the lowest mean value was on CPAP. In group 1, there was no significant difference between mean values of oxygen saturation on oxygen and CPAP, but there was a highly significant difference between mean values of oxygen saturation on oxygen and CPAP with oxygen, as well as on CPAP and CPAP with oxygen. In group 2, there was a significant difference between mean values of oxygen saturation on oxygen and CPAP, on nocturnal oxygen and CPAP with oxygen, as well as on CPAP and CPAP with oxygen. In group 1, it is better to prescribe nocturnal CPAP with oxygen than nocturnal oxygen alone or nocturnal CPAP alone to COPD patients with NOD in this group, whereas in group 2 it is better to prescribe nocturnal CPAP with oxygen, followed by nocturnal oxygen alone, compared with nocturnal CPAP alone to COPD patients with NOD in this group.

Severe nocturnal and postexercise hypoxia in children and adolescents with sickle cell disease.

Hypoxia is a common feature in children with sickle cell disease (SCD) that is inconsistently associated with painful crises and acute chest syndrome. To assess the prevalence and risk factors of hypoxia, we recorded daytime, nocturnal, and postexercise pulse oximetry (SpO2) values in 39 SCD patients with a median age of 10.8 years. Median daytime SpO2 was 97% (range, 89%–100%), and 36% of patients had daytime hypoxia defined as SpO2<96%. Median nocturnal SpO2 was 94.7% (range, 87.7%–99.5%), 50% of patients had nocturnal hypoxia defined as SpO2≤93%, and 11(37%) patients spent more than 10% of their total sleep time with SpO2<90%. Median postexercise SpO2 was 94% (range, 72%–100%) and 44.7% of patients had postexercise hypoxia defined as an SpO2 decrease ≥3% after a 6-minute walk test. Among patients with normal daytime SpO2, 35% had nocturnal and 42% postexercise hypoxia. Compared to 9 patients without daytime, nocturnal, or postexercise hypoxia, 25 patients with hypoxia under at least one of these three conditions had greater anemia severity (P = 0.01), lower HbF levels (P = 0.04), and higher aspartate aminotransferase levels (P = 0.03). Males predominated among patients with postexercise hypoxia (P = 0.004). Hypoxia correlated neither with painful crises nor with acute chest syndrome. Of 32 evaluable patients, 6 (18.8%) had a tricuspid regurgitation velocity ≥2.6 m/s, and this feature was associated with anemia (P = 0.044). Median percentage of the predicted distance covered during a 6-minute walk test was 86% [46–120]; the distance was negatively associated with LDH (P = 0.044) and with a past history of acute chest syndrome (P = 0.009). In conclusion, severe episodes of nocturnal and postexercise hypoxia are common in children with SCD, even those with normal daytime SpO2.

Ambulatory pulse oximetry monitoring in Japanese COPD outpatients not receiving oxygen therapy.

BackgroundIt remains unknown whether desaturation profiles during daily living are associated with prognosis in patients with chronic obstructive pulmonary disease (COPD). Point measurements of resting oxygen saturation by pulse oximetry (SpO2) and partial pressure of arterial oxygen (PaO2) are not sufficient for assessment of desaturation during activities of daily living. A small number of studies continuously monitored oxygen saturation throughout the day during activities of daily living in stable COPD patients. This study aims to analyse the frequency of desaturation in COPD outpatients, and investigate whether the desaturation profile predicts the risk of exacerbation.MethodsWe studied stable COPD outpatients not receiving supplemental oxygen therapy. Baseline assessments included clinical assessment, respiratory function testing, arterial blood gas analysis, body mass index, and the COPD Assessment Test (CAT). Patients underwent 24-hour ambulatory monitoring of SpO2 during activities of daily living. Exacerbations of COPD and death from any cause were recorded.ResultsFifty-one patients were enrolled in the study, including 12 current smokers who were excluded from the analyses in case high serum carboxyhaemoglobin concentrations resulted in inaccurately high SpO2 readings. The mean percent predicted forced expiratory volume in one second (%FEV1) was 50.9%. The mean proportion of SpO2 values below 90% was 3.0% during the day and 7.4% during the night. There were no daytime desaturators, defined as ≥ 30% of daytime SpO2 values below 90%. Twenty-one exacerbations occurred in 13 patients during the mean follow-up period of 26.4 months. Univariate and multivariate Cox proportional hazards analyses did not detect any significant factors associated with exacerbation.ConclusionsOur 24-hour ambulatory oximetry monitoring provided precise data regarding the desaturation profiles of COPD outpatients. Both daytime and nighttime desaturations were infrequent. The proportion of ambulatory SpO2 values below 90% was not a significant predictor of exacerbation.

Ambulatory pulse oximetry monitoring in Japanese COPD outpatients not receiving oxygen therapy

&#x0D; &#x0D; &#x0D; &#x0D; Background: It remains unknown whether desaturation profiles during daily living are associated with prognosis in patients with chronic obstructive pulmonary disease (COPD). Point measurements of resting oxygen saturation by pulse oximetry (SpO2) and partial pressure of arterial oxygen (PaO2) are not sufficient for assessment of desaturation during activities of daily living. A small number of studies continuously monitored oxygen saturation throughout the day during activities of daily living in stable COPD patients. This study aims to analyse the frequency of desaturation in COPD outpatients, and investigate whether the desaturation profile predicts the risk of exacerbation.&#x0D; Methods: We studied stable COPD outpatients not receiving supplemental oxygen therapy. Baseline assessments included clinical assessment, respiratory function testing, arterial blood gas analysis, body mass index, and the COPD Assessment Test (CAT). Patients underwent 24-hour ambulatory monitoring of SpO2 during activities of daily living. Exacerbations of COPD and death from any cause were recorded.&#x0D; Results: Fifty-one patients were enrolled in the study, including 12 current smokers who were excluded from the analyses in case high serum carboxyhaemoglobin concentrations resulted in inaccurately high SpO2 readings. The mean percent predicted forced expiratory volume in one second (%FEV1) was 50.9%. The mean proportion of SpO2values below 90% was 3.0% during the day and 7.4% during the night. There were no daytime desaturators, defined as ≥ 30% of daytime SpO2 values below 90%. Twenty-one exacerbations occurred in 13 patients during the mean follow-up period of 26.4 months. Univariate and multivariate Cox proportional hazards analyses did not detect any significant factors associated with exacerbation.&#x0D; Conclusions: Our 24-hour ambulatory oximetry monitoring provided precise data regarding the desaturation profiles of COPD outpatients. Both daytime and nighttime desaturations were infrequent. The proportion of ambulatory SpO2 values below 90% was not a significant predictor of exacerbation.&#x0D; &#x0D; &#x0D; &#x0D;

Daytime and Nocturnal Hypoxemia Are Related With Hemolysis In Adults With Sickle Cell Disease

▪ IntroductionDifferent studies had shown that nocturnal hypoxemia is associated with clinical complications in children with sickle cell disease (SCD), and, more recently, iron availability was related with nocturnal oxymetry in these children. However, there are few studies about this subject in adults with SCD, despite the fact that nocturnal hypoxemia occurred in 60% of the patients. We aimed to evaluate daytime and overnight hypoxia and its influence on clinical and laboratorial parameters in adults with SCD. Patients and Methods82 steady state patients with SCD followed at Anemia Out-Patient Clinic from Escola Paulista de Medicina/UNIFESP were invited to this study. This study was approved by Ethical Committee, and all patients agreed in participate. The daytime oximetry (SpO2) utilized was the mean of at least 3 measurements by pulse oximeter during regular appointments at the out-patient clinic. The nocturnal oximetry data (basal SpO2 and mean nocturnal SpO2) were obtained during polysomnography (PSG). Besides clinical evaluation, routine laboratory tests performed near the realization of the PSG were analyzed. The data was analyzed by parametric and non-parametric tests, with α=5%. ResultsThe median (range) age was 28 (18-69) years, and 44 (54%) were female. Moderate sleep apnea was diagnosed in 11% of the patients. The mean of SpO2 obtained for each measurement was: daytime SpO2: 95.1±4.3, basal SpO2: 94.3±3.5, and mean nocturnal SpO2: 93.3±3.6; with statistical significance between daytime and basal SpO2 (X2=17.0; p<0.001) and between daytime and mean nocturnal SpO2 (X2=10.3; p=0.001). The percentage of patients with hypoxemia (SpO2 ≤ 90%) varied according with the measurement: 14.1% at daytime SpO2, 13.7% at basal SpO2, and 20.0% at mean nocturnal SpO2. However, 55% of the patients achieved hypoxemia level during PSG. Association between daytime SpO2 and previous stroke was observed (X2=4.0; p=0.04). Patients with daytime and basal SpO2 ≤ 90% had higher lactate dehydrogenase (LDH) (634.3±114.9 and 538.0±198.3) compared to the ones with SpO2>90% (384.0±171.6 and 375.7±171.9; p<0.001 and p=0.02, respectively). Reticulocyte count was more elevated in patients with SpO2 ≤ 90% (daytime SpO2: 277,639.2±96,108.4; basal SpO2: 290,722.9±87,791.2 and mean nocturnal SpO2: 260,582.1±83,532.8) when compared to the ones with SpO2 >90% (185,537.3±90,445.7; 188,432.2±101,277.1 and 189,194.1±104,478.8; p=0.01; p=0.01 and p=0.03, respectively). No correlation was found within iron and SpO2. ConclusionDaytime and nocturnal hypoxemia showed effect on hemolytic markers in adults with SCD. Daytime SpO2 presented an association with previous stroke and considering that it was also observed an association between daytime and nocturnal SpO2, we suggest that daytime SpO2determination should be monitored in each appointment and can be used as a predictor of SCD severitySupported by CAPES/SUS and AFIP. Disclosures:No relevant conflicts of interest to declare.

Hematological and Genetic Predictors of Daytime Hemoglobin Saturation in Tanzanian Children with and without Sickle Cell Anemia

Low hemoglobin oxygen saturation (SpO2) is common in Sickle Cell Anemia (SCA) and associated with complications including stroke, although determinants remain unknown. We investigated potential hematological, genetic, and nutritional predictors of daytime SpO2 in Tanzanian children with SCA and compared them with non-SCA controls. Steady-state resting pulse oximetry, full blood count, transferrin saturation, and clinical chemistry were measured. Median daytime SpO2 was 97% (IQ range 94–99%) in SCA (N = 458), lower (P < 0.0001) than non-SCA (median 99%, IQ range 98–100%; N = 394). Within SCA, associations with SpO2 were observed for hematological variables, transferrin saturation, body-mass-index z-score, hemoglobin F (HbF%), genotypes, and hemolytic markers; mean cell hemoglobin (MCH) explained most variability (P < 0.001, Adj r 2 = 0.09). In non-SCA only age correlated with SpO2. α-thalassemia 3.7 deletion highly correlated with decreased MCH (Pearson correlation coefficient −0.60, P < 0.0001). In multivariable models, lower SpO2 correlated with higher MCH (β-coefficient −0.32, P < 0.001) or with decreased copies of α-thalassemia 3.7 deletion (β-coefficient 1.1, P < 0.001), and independently in both models with lower HbF% (β-coefficient 0.15, P < 0.001) and Glucose-6-Phosphate Dehydrogenase genotype (β-coefficient −1.12, P = 0.012). This study provides evidence to support the hypothesis that effects on red cell rheology are important in determining SpO2 in children with SCA. Potential mechanisms and implications are discussed.

The Young Everest Study: preliminary report of changes in sleep and cerebral blood flow velocity during slow ascent to altitude in unacclimatised children

BackgroundCerebral blood flow velocity (CBFV) and sleep physiology in healthy children exposed to hypoxia and hypocarbia are under-researched.AimTo investigate associations between sleep variables, daytime end-tidal carbon dioxide (EtCO2) and CBFV...