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Sex differences in respiratory and circulatory cost during hypoxic walking: potential impact on oxygen saturation.

ABSTRACT: Energy expenditure (EE) during treadmill walking under normal conditions (normobaric normoxia, 21% O₂) and moderate hypoxia (13% O₂) was measured. Ten healthy young men and ten healthy young women walked on a level (0°) gradient a range of speeds (0.67-1.67?m?s^-1). During walking, there were no significant differences in reductions in arterial oxygen saturation (SpO₂) between the sexes. The hypoxia-induced increase in EE, heart rate (HR [bpm]) and ventilation ([Formula: see text] [L min^-1]) were calculated. Using a multivariate model that combined EE, [Formula: see text], and HR to predict ?SpO₂ (hypoxia-induced reduction), a very strong fit model both for men (r²?=?0.900, P?2?=?0.957, P?2 were markedly different between men and women. [Formula: see text] and EE had a stronger effect on ?SpO₂ in women ([Formula: see text]: 4.1% in women vs. 1.7% in men; EE: 28.1% in women vs. 15.8% in men), while HR had a greater effect in men (82.5% in men and 67.9% in women). These findings suggested that high-altitude adaptation in response to hypoxemia has different underlying mechanisms between men and women. These results can help to explain how to adapt high-altitude for men and women, respectively.

SUBMITTER: Horiuchi M

PROVIDER: S-EPMC6606641 | biostudies-literature | 2019 Jul

REPOSITORIES: biostudies-literature

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Sex differences in respiratory and circulatory cost during hypoxic walking: potential impact on oxygen saturation.

Horiuchi Masahiro M Kirihara Yoko Y Fukuoka Yoshiyuki Y Pontzer Herman H

Scientific reports 20190702 1

Energy expenditure (EE) during treadmill walking under normal conditions (normobaric normoxia, 21% O2) and moderate hypoxia (13% O2) was measured. Ten healthy young men and ten healthy young women walked on a level (0°) gradient a range of speeds (0.67-1.67 m s-1). During walking, there were no significant differences in reductions in arterial oxygen saturation (SpO2) between the sexes. The hypoxia-induced increase in EE, heart rate (HR [bpm]) and vent ...[more]

PMID: 31266961

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Project description:Importance:Oxygenation index (OI), an invasive measurement, is routinely used as a marker of severity of hypoxemic respiratory failure in neonates. Oxygen saturation index (OSI) is a noninvasive measurement and has been shown to be a reliable surrogate marker of OI in children and adults with respiratory failure. Objectives:To evaluate the correlation of OI with OSI and to derive and validate predictive OI from noninvasive OSI measurements for clinically relevant OI values. Design, Setting, and Participants:For this retrospective cohort study, 220 neonates requiring invasive mechanical ventilation for hypoxic respiratory failure during the first 3 days of admission were recruited from a level III neonatal intensive care unit during a 6-year period, from January 1, 2012, to December 31, 2017. Data were analyzed from January 2017 to December 2017. Main Outcomes and Measures:The primary outcome was correlation of OI with OSI, analyzed using Pearson correlation coefficient. The secondary outcome was derivation and validation of OI from OSI. The data were split into derivative samples, from which a predictive equation for OI was derived using generalized linear model, and a validation sample was used to assess the predictive ability of the derived OI. Bland-Altman plot was used to assess agreement between derived OI and measured OI. Results:A total of 1442 paired OI and OSI measurements from 220 infants (190 preterm and 30 term; median [interquartile range] gestational age, 29 [26-33] weeks; mean [SD] birth weight, 1602 [1092] g) were recorded during the study. The median (interquartile range) number of samples was 5 (3-9) per patient. Overall, OI and OSI showed strong correlation (r = 0.89). The correlation was stronger in preterm infants (<28 weeks, r = 0.93; 28-33 weeks, r = 0.93) and within an oxygen saturation range of 85% to 95% (r = 0.94). The predictive derivative equation showed a strong linear association and good agreement in both derivation and validation data sets, with strong accuracy measures of derived OI for OI cutoffs of 5, 10, 15, 20, and 25. Conclusions and Relevance:A strong correlation of OI with OSI was found. Derived OI from OSI was in good agreement and strongly predictive of clinically relevant OI cutoffs from 5 to 25. Oxygenation index derived from noninvasive sources may be useful to reliably assess severity of respiratory failure and response to therapy on a continuous basis.

Project description:INTRODUCTION:The clinical importance of postoperative episodic hypoxemia is still unclear, and therefore largely under-studied. As a result, there is limited understanding of its relationship with early postoperative respiratory complications (PRC, defined as intubation within three days of surgery) and hospital resource utilization. MATERIALS AND METHODS:This single center study was performed using a retrospective observational design. We described population based definitions of desaturation from continuous SpO2 monitoring data captured in the post anesthesia care unit (PACU), namely median SpO2 in PACU, duration of desaturation below median, nadir desaturation, and length of oxygen therapy relative to PACU duration. These measures were evaluated against the occurrence of early PRC in logistic regression models. Measures that were independently associated with early PRC were accepted as the primary study exposures. Stratified logistic regression models were planned if significant interaction occurred with high risk surgical procedures. Models were adjusted by including several patient conditions, procedural, and anesthesia risk factors. Propensity matching on desaturation occurrence was planned to evaluate the relationship with postoperative resource utilization. RESULTS:Among 125,740 patients included in the univariate analyses, 351 patients (0.3%) developed early PRC. Nadir desaturation <89% [14.3% of patients; adjusted odds ratio 2.02; 95% CI 1.52, 2.68; p<0.001] and PACU oxygen therapy requirements greater than 60 min [adjusted odds ratio 1.92 (>60 min) to 3.04 (>90 min); p<0.001] were identified as independent predictors of early PRC occurrence. A modest interaction was observed between desaturation and higher surgical risk. Propensity matching for postoperative oxygen requirement was performed in 37,354 matched patients. Matched analysis demonstrated significant increase in day of surgery charges, respiratory charges, total charges, hospital length of stay, reintubation and use of invasive or non-invasive ventilatory support. CONCLUSIONS:In summary, we report that prolonged PACU oxygen therapy and nadir desaturation <89% in PACU as captured in a retrospective database are independently associated with early PRC. This study describes resource implications of PACU desaturation in a large academic medical center in North America.

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Sex differences in respiratory and circulatory cost during hypoxic walking: potential impact on oxygen saturation.

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Sex differences in respiratory and circulatory cost during hypoxic walking: potential impact on oxygen saturation.

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