PURPOSE: Assessing fluid responsiveness relying on central venous oxygen saturation (ScvO₂) yields varied outcomes across several studies. This study aimed to determine the ability of the change in ScvO₂ (ΔScvO₂) to detect fluid responsiveness in ventilated septic shock patients and potential influencing factors. METHODS: In this prospective, single-center study, all patients conducted from February 2023 to January 2024 received fluid challenge. Oxygen consumption was measured by indirect calorimetry, and fluid responsiveness was defined as an increase in cardiac index (CI) ≥ 10% measured by transthoracic echocardiography. Multivariate linear regression analysis was conducted to evaluate the impact of oxygen consumption, arterial oxygen saturation, CI, and hemoglobin on ScvO₂ and its change before and after fluid challenge. The Shapiro-Wilk test was used for the normality of continuous data. Data comparison between fluid responders and non-responders was conducted using a two-tailed Student t-test, Mann Whitney U test, and Chi-square test. Paired t-tests were used for normally distributed data, while the Wilcoxon signed-rank test was used for skewed data, to compare data before and after fluid challenge. RESULTS: Among 49 patients (31 men, aged (59 ± 18) years), 27 were responders. The patients had an acute physiology and chronic health evaluation II score of 24 ± 8, a sequential organ failure assessment score of 11 ± 4, and a blood lactate level of (3.2 ± 3.1) mmol/L at enrollment. After the fluid challenge, the ΔScvO₂ (mmHg) in the responders was greater than that in the non-responders (4 ± 6 vs. 1 ± 3, p = 0.019). Multivariate linear regression analysis suggested that CI was the only independent influencing factor of ScvO₂, with R² = 0.063, p = 0.008. After the fluid challenge, the change in CI became the only contributing factor to ΔScvO₂ (R² = 0.245, p < 0.001). ΔScvO₂ had a good discriminatory ability for the responders and non-responders with a threshold of 4.4% (area under the curve = 0.732, p = 0.006). CONCLUSION ΔScvO₂ served as a reliable surrogate marker for ΔCI and could be utilized to assess fluid responsiveness, given that the change in CI was the sole contributing factor to the ΔScvO₂. In stable hemoglobin conditions, the absolute value of ScvO₂ could serve as a monitoring indicator for adequate oxygen delivery independent of oxygen consumption.
Humans ; Shock, Septic/blood* ; Male ; Female ; Middle Aged ; Prospective Studies ; Oxygen Saturation ; Aged ; Fluid Therapy ; Oxygen/blood* ; Oxygen Consumption ; Adult

Humans ; Child ; Cardiovascular Diseases/diagnosis* ; Exercise Test ; Oxygen Consumption

A high-precision human metabolic measurement system is designed. The system uses STM32F103 as the main control chip to acquire oxygen, carbon dioxide and flow signals to calculate four quantitative indicators: oxygen consumption(V_O2), carbon dioxide production(V_CO2), respiratory entropy(RQ) and resting energy metabolism(REE), and finally uses an upper computer to display the calculation results.In this paper, the signal acquisition circuit design was carried out for the oxygen sensor, carbon dioxide sensor and flow sensor, and the validity of the device was verified with the American machine MGCDiagnositcs using Bland-Altman analysis method, and the results showed that the four parameters of V_O2,V_CO2, RQ and REE of both devices fell in the agreement interval of more than 95%. The device thus provides accurate metabolic measurements and offers an effective tool for the field of general health and clinical nutrition support in China.
Calorimetry, Indirect ; Carbon Dioxide/metabolism* ; Energy Metabolism ; Humans ; Oxygen ; Oxygen Consumption

Objective: To investigate the postoperative cardiopulmonary fitness of children with congenital heart diseases (CHD). Methods: This is a retrospective study. A total of 136 children after cardiac correction undergoing cardiopulmonary exercise test (CPET) in Shanghai Children's Medical Center from March 1 to June 30, 2021 were selected. According to the surgical procedure, the children were divided into two groups: the biventricular correction group (BV group) (n=75) and single ventricular correction group (SV group) (n=61). The BV group was divided into two subgroups: simple congenital heart disease (S-CHD) group (n=35) and complex congenital heart disease (C-CHD) group (n=40). CPET parameters, including VO₂ max, VO₂/kg max, VO₂/kg@AT, O₂/HR max, HRR, PetCO₂ max, CI, HRR at 1 min, VE/VCO₂ slope, OUES/kg and EOV, were analyzed. CPET parameters of patients underwent different procedure were compared. In the subgroup analysis, CPET parameters of patients in S-CHD group and C-CHD group were compared. The parameters of the BV group were compared with the normal value. Linear correlation analysis was used to identify the correlation between the CPET parameters. Results: A total of 136 children with CHD after surgery were enrolled. The age was (9.4±3.1) (ranged 6.2-16.0) years, and there was 84 (61.8%) male. All the children completed CPET examination safely without experiencing serious circulation abnormalities. Compared with the SV group, the VO₂/kg max ((32.6±6.9) ml·kg^-1·min^-1 vs. (23.5±5.9) ml·kg^-1·min^-1, P<0.001), O₂/HR max ((7.24±2.93) ml/beat vs. (6.35±2.17)ml/beat, P=0.030), HRR at 1 min ((32.5±13.9) beat/min vs. (26.3±12.5) beat/min, P=0.036), OUES/kg (36.9±8.8 vs. 29.7±11.8, P=0.001) were significantly higher, VE/VCO₂ slope (29.1±5.20 vs. 35.1±8.0, P<0.001) and incidence of EOV (32.0%(24/75) vs. 57.4%(31/61), P=0.027) were significantly lower in BV group. Compared with the simple CHD subgroup, VE/VCO₂ slope and the incidence of EOV were higher, VO₂/kg max, O₂/HR max, HRR at 1 min and OUES/kg were lower in the complex CHD subgroup (all P<0.05). Cardiopulmonary function parameters of the BV group were lower than the normal value. Linear correlation analysis showed that VO₂/kg@AT was strongly correlated with VO₂/kg max (r=0.86, P<0.001), VO₂/kg max was strongly correlated with OUES/kg (r=0.63, P<0.001), HRR was strongly correlated with CI (r=0.91, P<0.001), and VO₂/kg max was strongly correlated with OUES/kg (r=0.63, P<0.001). VE/VCO₂ slope was strongly correlated with PetCO₂ max (r=1.00, P<0.001). Conclusions: The exercise cardiopulmonary function of children after single ventricular correction is weaker than that of biventricular correction, and the exercise tolerance of children after biventricular correction is lower than that of normal children. Among the children after biventricular correction, the exercise tolerance of children with complex CHD is lower than that of children with simple CHD. Postoperative CPET is of important realistic significance for CHD children.
Adolescent ; Child ; China ; Exercise Test/methods* ; Female ; Heart Defects, Congenital/surgery* ; Humans ; Male ; Oxygen Consumption ; Retrospective Studies

Objective: To evaluate the consistency on the determination of target heart rate by simple calculation method based on resting heart rate and by anaerobic threshold method in cardiopulmonary exercise test (CPET) for patients with coronary artery disease after percutaneous coronary intervention (PCI). Methods: This study was a diagnostic test. Patients with coronary artery disease who underwent the first PCI in the Department of Cardiology of Peking University People's Hospital from October 2011 to April 2021 were enrolled. Patients were further divided into subgroups according to gender, age (<60 years group and ≥60 years group), with or without myocardial infarction history (myocardial infarction group and angina pectoris group) and whether β blockers were applied. The general clinical data of patients, resting heart rate (RHR) and anaerobic threshold heart rate in CPET were collected through the electronic medical record system. The simple target rate (RHR plus 20 or 30 bpm) and the target rate calculated by anaerobic threshold (anaerobic threshold heart rate minus 10 bpm) were both calculated in each patient. Consistency test of target heart rate derived by above the two methods was shown by intra-class correlation (ICC) and Bland-Altman plots. Results: A total of 439 patients were included, age was (56.2±8.8) years, body mass index was (25.77±2.34) kg/m², there were 382 males (87.0%). The target heart rate determined by anaerobic threshold method was (90.0±11.8)bpm, and the simple target heart rate determined by RHR plus 20 bpm was (91.0±8.4)bpm. There was no significant difference on the target heart rate derived from the two calculation methods (P=0.091). The simple target heart rate determined by RHR plus 30 bpm was (101.0±8.4)bpm, which was significant higher than that determined by anaerobic threshold method (P<0.001). In the following analysis, RHR plus 20 bpm was defined as the simple target heart rate. The ICC value of target heart rate determined by anaerobic threshold and resting rate plus 20 bpm was 0.529(95%CI 0.458-0.593, P<0.001). Bland-Altman plots analysis showed that the ratio of the simple target heart rate and the target heart rate determined by anaerobic threshold method was 1.03±0.11 and the 95% limits of agreement (LOA) were 0.812-1.245. In the subgroup of patients aged<60 years (n=247), the ICC value was 0.492, the ratio by Bland-Altman plots analysis was 1.02±0.11 and LOA was 0.814-1.234; in the subgroup of patients aged ≥60 years (n=192), the ICC value was 0.566, the ratio by Bland-Altman plots analysis was 1.03±0.11 and LOA was 0.810-1.260. In male subgroup(n=382), the ICC value was 0.540, the ratio by Bland-Altman plots analysis was 1.03±0.11 and LOA was 0.813-1.246; in female subgroup(n=57), the ICC value was 0.445, the ratio by Bland-Altman plots analysis was 1.03±0.11 and LOA was 0.810-1.240.In myocardial infarction subgroup (n=186), the ICC value was 0.568, the ratio by Bland-Altman plots analysis was 1.02±0.11 and LOA was 0.810-1.227; in angina pectoris subgroup (n=253), the ICC value was 0.495, the ratio by Bland-Altman plots analysis was 1.04±0.11 and LOA was 0.813-1.260. In the subgroup of patients with β blockers (n=353), the ICC value was 0.520, the ratio by Bland-Altman plots analysis was 1.03±0.11 and LOA was 0.810-1.252; in the subgroup of patients without β blockers (n=86), the ICC value was 0.570, the ratio by Bland-Altman plots analysis was 1.02±0.10 and LOA was 0.821-1.219. Conclusions: The simple target heart rate determined by RHR plus 20 bpm is consistent with the target heart rate determined by anaerobic threshold in patients with coronary artery disease after PCI. But the simple target heart rate determined by RHR plus 20 bpm can't replace the target heart rate determined by anaerobic threshold in this patient cohort.
Adrenergic beta-Antagonists ; Anaerobic Threshold ; Angina Pectoris ; Coronary Artery Disease ; Female ; Heart Rate/physiology* ; Humans ; Male ; Myocardial Infarction ; Percutaneous Coronary Intervention

OBJECTIVE: This study evaluated the effect of maximal oxygen pulse (O ₂P _max) on patients with chronic obstructive pulmonary disease (COPD) and confirmed the predictive effect on acute exacerbations of COPD (AECOPD). METHODS: This retrospective study included 91 participants who underwent cardiopulmonary exercise testing (CPET), lung function testing, a dyspnea scale assessment, and a 3-year follow-up. The participants were divided into two groups according to the O ₂P _max value. Exercise capacity, ventilatory conditions, gas exchange efficiency, and dyspnea symptoms were compared, and the correlations between O ₂P _max and these indices were evaluated. The ability of O ₂P _max to predict AECOPD was examined. RESULTS: Exercise capacity, ventilatory conditions, and gas exchange efficiency were lower, and dyspnea symptom scores were higher in the impaired O ₂P _max group ( P < 0.05). O ₂P _max was positively correlated with forced vital capacity (FVC)%, forced expiratory volume in 1 sec (FEV ₁)%, FEV ₁/FVC%, anaerobic threshold (AT), work rate (WR)%, aximal oxygen uptake (V̇O _2max)%, V̇O ₂/kg _max, V̇O ₂/kg _max%, WR _AT, WR _max, V̇O _2AT, V̇O _2max, and V̇ _Emax, and was negatively correlated with EqCO _2AT, and EqCO _2max ( P < 0.05). Most importantly, O ₂P _max could be used to predict AECOPD, and the best cut-off value was 89.5% (area under the curve, 0.739; 95% CI, 0.609-0.869). CONCLUSION O ₂P _max reflected exercise capacity, ventilation capacity, gas exchange capacity, and dyspnea symptoms in patients with COPD and may be an independent predictor of AECOPD.
Dyspnea/etiology* ; Exercise Tolerance ; Humans ; Oxygen ; Oxygen Consumption ; Pulmonary Disease, Chronic Obstructive ; Retrospective Studies

Objective: To investigate the correlation between heart rate index (HRI), systolic blood pressure(SBP) peak-to-SBPrest ratio (SBPR) and peak oxygen consumption (peakVO₂) in patients with chronic heart failure (CHF), and discuss the possibility of using HRI and SBPR collected during exercise to assess the exercise tolerance of CHF patients in the absence of gas analysis. Methods: In this cross-sectional study, a total of 547 patients with CHF who underwent cardiopulmonary exercise test(CPET) in Tongji Hospital Heart Rehabilitation Center Affiliated to Tongji University from March 2007 to December 2018 were collected retrospectively, focusing on their clinical data including age, gender, type of heart failure,BMI as well as data collected during their CPETs, such as peakVO₂, HRI and SBPR. Spearman univariate correlation analysis was used for statistical analysis, to unveil the correlations between peakVO₂ and those parameters, and multiple linear regression analysis was also conducted. Results: A total of 547 CHF patients conducting CPET were included in this research, of which 447 were male, at age of 63(56, 69). Univariate analysis indicates that HRI, SBPR and peakVO₂ showed significant positive correlation (r=0.323, 0.263, respectively, all P<0.001); Age and peak VO₂ showed significant negative correlation(r=-0.207, P<0.001); Male patients showed peakVO₂ higher than female(r=-0.229, P<0.001); PeakVO₂ of heart failure with reduced ejection fraction(HFrEF) was lower than heart failure with mid-range ejection fraction(HFmrEF)and heart failure with preserved ejection fraction(HFpEF) (r=0.181, P<0.001). Body mass index (BMI) had no significant correlation with peakVO₂ (P>0.05). Multivariate linear regression analysis showed that the HRI, SBPR were positively correlated with peakVO₂(t=7.68, 5.08, respectively, all P<0.05), while age and BMI showed negative correlation with peakVO₂(t=-5.43, -0.31, respectively, all P<0.05). PeakVO₂ of male was higher than female(t=-6.03, P<0.05), and peakVO₂ of HFrEF was lower than those of HFmrEF and HFpEF(t=3.17, 4.48, respectively, all P<0.05). A linear equation (F=33.52, adjusted R²=0.29) could be constructed: peakVO₂=10.65(male) or 8.53(female)+4.26HRI+3.31SBPR-0.07age-0.13BMI+0(HFrEF) or 1.05 (HFmrEF) or 1.62(HFpEF). Conclusion: HRI and SBPR are positively correlated with peakVO₂. In the absence of gas analysis, it is possible to apply HRI and SBPR during exercise to predict exercise tolerance in patients with CHF.
Chronic Disease ; Cross-Sectional Studies ; Female ; Heart Failure ; Heart Rate ; Humans ; Male ; Oxygen Consumption/physiology* ; Prognosis ; Retrospective Studies ; Stroke Volume/physiology*

Objective: The aim of this study was to investigate scuba diving induced exercise response in novice divers as required in open water scuba diving certification. Methods: Maximal cardiopulmonary exercise test (CPET) was performed in 30 novice divers before and within 24 hours after a standard scuba diving open water certification diving protocol of four open water dives. Results: A significant increase in maximal oxygen consumption (VO2max) in mL·kg-1·min-1 after scuba diving training [25.84 (6.0) vs. 27.04 (7.0)] (p<0.05) suggestive of an increase in exercise performance. Ventilatory drive (VE/VCO2) also showed a significant increase 27.95 (2.7) vs. 30.07 (5.3). Ventilatory anaerobic threshold (VAT), blood pressure and lung function parameters showed no significant differences with open water scuba diving certification training. Conclusion In novice divers, repeated training exposure during open water scuba diving certification results in increased cardiorespiratory fitness. Although further corroborating studies are needed, this would suggest that recreational scuba diving may be an option for exercise promotion in the future.
Diving ; Diving and Hyperbaric Medicine ; Oxygen Consumption ; Exercise

Anaerobic Threshold ; Exercise Test ; Female ; Heart Rate ; Lactic Acid ; Lung ; Male

Objective: To investigate the effects of ticagrelor on cardiorespiratory fitness in patients with coronary heart disease after percutaneous coronary intervention (PCI). Methods: A total of 1 073 patients, who were diagnosed as coronary heart disease and underwent cardiopulmonary exercise testing (CPET) within 1 year after PCI, were enrolled from September 2017 to September 2019 in Peking University Third Hospital, including 309 patients in ticagrelor group and 764 patients in clopidogrel group. Clinical information, blood test results, echocardiographic parameters, cardiorespiratory fitness related parameters (including peak oxygen uptake (VO(2)), anaerobic threshold VO(2), peak oxygen pulse (VO(2)/HR) and carbon dioxide ventilation equivalent (VE/VCO(2)) slope), coronary lesions and intervention information were obtained. Cardiopulmonary fitness related indexes were compared between the two groups, and the correlation between ticagrelor use and cardiopulmonary fitness related indexes was analyzed by multivariate logistic regression. Patients who underwent CPET within 1 month after PCI were included in the subgroup analysis. Results: In ticagrelor group, the age was (60.3±10.3) years, and 253(81.9%) cases were male. The age of clopidogrel group was (60.6±10.0) years, and there were 608(79.6%) males. No significant differences were observed in peak VO(2), anaerobic threshold VO(2), and peak VO(2)/HR between the two groups (all P>0.05), but the VE/VCO(2) slope was significantly higher in the ticagrelor group than in the clopidogrel group (30.075 (27.207, 33.603) vs. 28.853 (25.970, 32.336), P<0.001). Logistic regression analysis suggested that the peak VO(2), anaerobic threshold VO(2) and peak VO(2)/HR were not significantly correlated with the ticagrelor use (all P>0.05), while the VE/VCO(2) slope was independently correlated with ticagrelor use (OR=1.098, 95%CI 1.032-1.168, P=0.003). Subgroup analysis of patients who underwent CPET within 1 month after PCI also indicated that no significant difference were observed in peak VO(2), anaerobic threshold VO(2), peak VO(2)/HR and VE/VCO(2) slope between the two groups (all P>0.05). Logistic regression analysis suggested that the peak VO(2), anaerobic threshold VO(2) and peak VO(2)/HR were not significantly correlated with ticagrelor use (all P>0.05), while the VE/VCO(2) slope was significantly correlated with ticagrelor use (OR=1.132, 95%CI 1.030-1.244, P=0.010). Conclusion: Among coronary heart disease patients after PCI, treatment with clopidogrel does not result in significant decrease in exercise endurance as compared with patients treated with ticagrelor.
Aged ; Cardiorespiratory Fitness ; Exercise Test ; Female ; Heart Failure ; Humans ; Male ; Middle Aged ; Oxygen Consumption ; Percutaneous Coronary Intervention ; Ticagrelor