Arterial Oxygen Research Articles

E-selectin and asymmetric dimethylarginine plasma levels in adult cyanotic congenital heart disease patients: relation to biochemical parameters, vascular function, and clinical status.

Abstract Background and Aim Patients with cyanosis secondary to congenital heart disease (CHD) are characterized by erythrocytosis and increased blood viscosity, which contributes to endothelial dysfunction, increased arterial stiffness, and impaired vascular function, which may affect the final clinical presentation. Asymmetric dimethylarginine (ADMA) and e-selectin (e-sel) are valuable biomarkers for prognosis of endocardial dysfunction and vascular damage. Their concentration levels in blood serum have the potential to be a rapid and easily accessible tool that reflects the severity of the disease. We aimed to assess e-sel and ADMA levels, their relationship with clinical status, as well as endothelial and vascular function. Methods A cross-sectional study including 36 adult CHD cyanotic patients [(17 males)(42.3 +/- 16.3 years)] with arterial blood oxygen saturation less than 92% and 20 healthy controls [(10 males)( 38.2 +/- 8.5 years)] was performed. All patients underwent clinical examination, blood testing, and cardiopulmonary tests. Endothelial function was assessed using intima-media thickness and flow-mediated dilatation (FMD). Vascular function using applanation tonometry methods was completed while considering aortic systolic pressure, aortic pulse pressure (AoPP), augmentation pressure (AP), augmentation index (AI), pulse pressure amplification (PPampl), and pulse wave velocity (PWV). Results Concentrations of e-sel and ADMA were significantly higher in patients with CHD than in controls (56.3 ± 13.6 ng/mL vs. 15.5 +/- 8.6 ng/mL, p<0.001) and (1.48 ± 0.48 ng/mL vs. 0.46 ± 0.1 ng/mL, p<0.001) respectively. E-sel levels correlated with gender, blood oxygen saturation, red blood cell, hemoglobin concentration, hematocrit, augmentation pressure, forced expiratory one second volume, forced vital capacity, and oxygen uptake. ADMA levels were found to correlate with age only. Conclusions E-sel level, unlike ADMA concentration, reflects the degree of severity of erythrocytosis and hypoxia and, thus, the physical status of patients with cyanotic CHD. E-selectin predicts increased augmentation pressure.Figure 1.A) ROC analysis for e-selectin

Comparing the effects of oral sucrose and kangaroo mother care on selected physiological variables and pain resulting from venipuncture in premature newborns admitted to neonatal intensive care units

BackgroundPremature newborns admitted to neonatal intensive care units (NICUs) undergo numerous painful interventions during care and treatment. The purpose of this study was to compare the effects of using sucrose and kangaroo mother care by on selected physiological variables and pain resulting from venipuncture in premature infants admitted to NICUs affiliated with Shiraz University of Medical Sciences.MethodsThis clinical trial included premature infants admitted to 2 NICUs. The sample size consisted of 66 neonates, with 22 newborns in each group. Randomization was performed using the block allocation method. Data collection involved a demographic questionnaire, the neonatal infant pain scale, and a pulse oximetry device. Friedman, Kruskal–Wallis, and Dunn’s post hoc tests employed for data analysis, with a significance level of P < 0.05.ResultsThe use of oral sucrose and kangaroo care demonstrated significant differences in breathing rate, heart rate, and average arterial blood oxygen saturation during and after venipuncture (P < 0.05). Oral sucrose was found to be significantly more effective than kangaroo care. Neonates under kangaroo care exhibited more regular heart rates compared to the other group (P < 0.05). The utilization of oral sucrose and kangaroo care had varying effects on the average pain score resulting from venipuncture in premature neonates (P < 0.05).ConclusionsBoth methods proved effective in reducing pain and improving physiological variables. However, due to the superior effectiveness of sucrose administration, it is recommended as a cost-effective and easily implementable method in NICUs.Trial registration: Iranian Registry of Clinical Trials IRCT20191215045749N1. (29/03/2020).

Sedation for awake tracheal intubation: A systematic review and network meta-analysis.

Different sedation regimens have been used to facilitate awake tracheal intubation, but the evidence has not been synthesised robustly, particularly with respect to clinically important outcomes. We conducted a systematic review and network meta-analysis to determine the sedation techniques most likely to be associated with successful tracheal intubation, a shorter time to successful intubation and a lower risk of arterial oxygen desaturation. We searched for randomised controlled trials of patients undergoing awake tracheal intubation for any indication and reporting: overall tracheal intubation success rate; tracheal intubation time; incidence of arterial oxygen desaturation; and other related outcomes. We performed a frequentist network meta-analysis for these outcomes if two or more sedation regimens were compared between included trials. We also performed a sensitivity analysis excluding trials with a high risk of bias. In total, 48 studies with 2837 patients comparing 33 different regimens were included. Comparing overall awake tracheal intubation success rates (38 studies, 2139 patients), there was no evidence suggesting that any individual sedation regimen was superior. Comparing times to successful tracheal intubation (1745 patients, 24 studies), any sedation strategy was superior to placebo. When we excluded trials with a high risk of bias, we found no evidence of a difference between any interventions for time to successful tracheal intubation. Thirty-one studies (1753 patients) suggested that dexmedetomidine and magnesium sulphate were associated with a reduced risk of arterial oxygen desaturation compared with other interventions, but excluding trials with a high risk of bias suggested no relevant differences between interventions. The quality of evidence for each of our outcomes was low. To maximise effective and safe awake tracheal intubation, optimising oxygenation, topical airway anaesthesia and procedural performance may have more impact than any given sedation regimen.

Association between arterial oxygen tension with clinical outcomes in patients undergoing VA-ECMO support: a systematic review and dose-response meta-analysis

Abstract Background Arterial hyperoxia has been associated with a worse prognosis in critically ill patients. However, studies conducted in patients undergoing Veno-Arterial Extracorporeal Membrane Oxygenation (VA-ECMO) used inconsistent and arbitrary thresholds for defining hyperoxia, which impeded the determination of the optimal target for arterial oxygen tension (PaO2) in this population. Purpose To investigate and visualise the dose-response relationship between post-ECMO level of PaO2 with early mortality (in-hospital and 1-month) and poor neurological outcomes in adult patients undergoing VA-ECMO support, including Extracorporeal Cardiopulmonary Resuscitation (ECPR). Methods A systematic search was conducted through Pubmed and Embase to include studies that stratified patients based on PaO2 levels and evaluated relevant outcomes. We utilised either adjusted Odds Ratio (OR) with 95% Confidence Interval (CI) when available, or unadjusted OR against the lowest exposure category. The median, mean, or midpoint value of PaO2 was assigned as the corresponding dose. A random-effects one-stage dose-response meta-analysis was performed to assess linear association for every 10 mmHg increase in PaO2, while potential non-linear relationship was explored with restricted cubic splines at 3 knots (10th, 50th, and 90th percentile). Non-linearity was assessed by using Wald test with p value &amp;lt;0.05 considered significant. Statistical analyses were performed using STATA 17.0. Results Fourteen eligible records were identified (cardiogenic shock/CS = 5 records; ECPR = 8 records; both = 1 record). Only four studies classified a separate category for hypoxemic patients (&amp;lt;60 mmHg). PaO2 levels were measured within 24-72 hours of VA-ECMO initiation, except in one study. PaO2 level was not associated with early mortality (9 studies; OR 1.021 [95% CI 0.988–1.055]; p for non-linearity = 0.893), but found to have a linear association with composite poor neurological outcomes (6 studies; OR 1.016 [1.009–1.024]; p for non-linearity = 0.346). Subgroup analysis of CS patients revealed a linear association between PaO2 &amp;gt;100 mmHg and early mortality (4 studies; OR 1.025 [95%CI 1.018–1.032]; p for non-linearity = 0.255). For ECPR patients, a J-shaped relationship was observed between PaO2 and early mortality (5 studies; p for non-linearity = 0.004), with the lowest odds being at PaO2 level of 110-210 mmHg, while PaO2 level &amp;gt;110 mmHg showed a linear trend towards higher odds of poor neurological function (4 studies; OR 1.091 [95%CI 0.938–1.269]; p for non-linearity = 0.257). Conclusion Pooled data from observational studies suggest that PaO2 &amp;gt;100 mmHg should be avoided in CS patients on VA-ECMO support, given its linear association with mortality, but it cannot be extrapolated to hypoxemic patients. In ECPR patients, PaO2 level around 110-210 mmHg conferred the best clinical outcomes. However, these findings should be confirmed through randomised controlled trials.

Use of esketamine for tracheoscopic drug injection: a randomized controlled trial

BackgroundSufentanil may induce hypotensive bradycardia and other adverse reactions in elderly patients during anesthesia, while esketamine exhibits sedative and analgesic effects with minimal impact on respiration and circulation. The objective of this study was to investigate the impact of these two anesthetics on vital signs in patients undergoing bronchoscopy and lavage under general anesthesia.MethodThis study was a randomized controlled trial with a parallel design. A total of 100 patients aged ≥60 years with ASAI or II who were undergoing bronchoscopy and lavage were randomly assigned to two groups: group A (esketamine, n = 50) and group B (sufentanil, n = 50). During anesthesia induction, both groups received intravenous infusion of propofol at a dose of 1.5 mL/kg and atracurium. In group A, esketamine at a dose of 0.3 mg/kg was injected; in group B, sufentanil at a dose of 0.2 μg/kg was injected intravenously. Subsequently, a laryngeal mask was inserted and connected to an anesthesia machine for mechanical ventilation. Anesthesia maintenance involved continuous intravenous infusion of propofol at a dose of 3 mL/kg. The mean arterial pressure (MAP), heart rate (HR), and blood oxygen saturation (SpO2) were recorded at various time points: before anesthesia injection (T0), after laryngeal mask insertion (T1), 5 min after the operation started (T2), 15 min after the operation started (T3), and before the end of the operation (T4). Additionally, the recovery time was recorded.ResultsThe blood pressure of patients in the esketamine group exhibited higher levels compared to those in the sufentanil group at multiple time points during the operation, while maintaining a more stable intraoperative blood pressure and shorter postoperative recovery time than that observed in the sufentanil group. The blood pressure and heart rate of patients in the esketamine group exhibited significant fluctuations after laryngeal mask implantation compared to pre-anesthesia induction, with a statistically significant increase observed. Conversely, no significant changes were observed in the sufentanil group. The heart rate and oxygen saturation showed no significant differences between the two groups, nor did the amount of propofol administered during the procedure.ConclusionThe utilization of esketamine during the induction phase of bronchoscopy and lavage under general anesthesia can enhance hemodynamic stability and reduce the occurrence of hypotension, thereby facilitating postoperative anesthetic recovery.

Effects of endurance exercise under hypoxic conditions on the gastric emptying rate and intestinal cell damage.

The present study examined the effects of gastric emptying rate and intestinal cell damage following a single session of endurance exercise under "hypoxic" or "normoxic" conditions at the same relative intensity. Eleven healthy males performed two trials on different days, consisting of a 60min run on a treadmill at 70% maximal running velocity (vMax) while inspiring hypoxic (FiO2: 14.5%; HYP) or normoxic air (FiO2: 20.9%; NOR). The average running velocity was 11.4 ± 0.7km/h in NOR and 10.8 ± 0.5km/h in HYP, respectively. Venous blood samples were collected to evaluate plasma intestinal fatty acid binding protein (I-FABP) as an indicator of exercise-induced intestinal cell damage. The gastric emptying rate was determined by the 13C-sodium acetate breath test. Running velocities at 70% vMax and arterial oxygen saturation were significantly lower under HYP than NOR (p < 0.001). Peak heart rate and rating of perceived exertion during exercise did not differ significantly between the trials. Maximum 13C excretion time (an indication of the gastric emptying rate) was significantly delayed in the HYP (NOR: 38.5 ± 5.0min, HYP: 45.5 ± 9.6min; p = 0.010). Furthermore, the score of nausea increased slightly, but increased significantly after exercise only in the HYP (p = 0.04). However, exercise-induced changes in plasma I-FABP, adrenaline, and noradrenaline concentrations did not differ significantly between the two trials. These results suggest that endurance exercise under hypoxic conditions impairs digestive function in the stomach compared to exercise under normoxic conditions performed at the same relative intensity.

Oxygen Delivery and Consumption in Patients Who Are Comatose After Out-of-Hospital Cardiac Arrest Are Affected by Blood Pressure Target.

In the management of patients resuscitated from out-of-hospital cardiac arrest, a primary goal is to restore sufficient oxygen delivery (DO2) to meet demands in oxygen consumption (VO2). This post hoc analysis of the BOX (Blood Pressure and Oxygen Targets) study included adult patients who were comatose and experienced out-of-hospital cardiac arrest from a presumed cardiac cause, who were randomized to a mean arterial blood pressure (MAP) target of 63 mm Hg (MAP63) or 77 mm Hg (MAP77) and a Restrictive PaO2 target of 9 to 10 kPa versus a Liberal target of 13 to 14 kPa in a 2×2 factorial design. A pulmonary artery catheter was inserted following randomization. DO2 and VO2 were calculated as: DO2=cardiac output × arterial oxygen content, and VO2= cardiac output × arteriovenous oxygen difference. Of 789 patients, 730 (92.5%) were included in this substudy. A total of 362 patients were randomized to MAP77, and 368 to MAP63, 368 to a liberal Pao2 target, and 362 to a restrictive target. At all prespecified time points, DO2 in MAP77 was higher compared with MAP63, with a cumulative treatment effect of 203 L (95% CI, 132-274) O2 after 36 hours. VO2 was higher in MAP77 after 36 hours, with a cumulative treatment effect of 21.9 L (95% CI, 5.8-38) O2, compared with the MAP63 group. Targeting a MAP of 77 mm Hg resulted in an overall increase in DO2 and a smaller increase in VO2 compared with a MAP target of 63 mm Hg. A higher Pao2 target did not result in any difference in DO2 or VO2.

Low oxygen saturation and discordant arterial blood gas measures have diagnosed a case of hemoglobinopathy

Pulse oximeter is a simple non-invasive equipment used to determine patient’s arterial blood oxygen saturation (SpO2). However, in some people, arterial blood gas measures (SaO2) are normal and low SpO2 values are related to hemoglobin variant rather than cardiac or pulmonary illnesses. Aim. We present a case of thalassemia that manifested with low SpO2 and discordant SaO2. Conclusion. When examining a patient with an unusually low SpO2, the differential diagnosis of a suspected hemoglobin variant should be investigated. Establishing an accurate diagnosis as soon as possible may help avoid unnecessary tests.

Higher oxygen content and transport characterize high-altitude ethnic Tibetan women with the highest lifetime reproductive success

We chose the "natural laboratory" provided by high-altitude native ethnic Tibetan women who had completed childbearing to examine the hypothesis that multiple oxygen delivery traits were associated with lifetime reproductive success and had genomic associations. Four hundred seventeen (417) women aged 46 to 86 y residing at ≥3,500 m in Upper Mustang, Nepal, provided information on reproductive histories, sociocultural factors, physiological measurements, and DNA samples for this observational cohort study. Simultaneously assessing multiple traits identified combinations associated with lifetime reproductive success measured as the number of livebirths. Women with the most livebirths had distinctive hematological and cardiovascular traits. A hemoglobin concentration near the sample mode and a high percent of oxygen saturation of hemoglobin raised arterial oxygen concentration without risking elevated blood viscosity. We propose ongoing stabilizing selection on hemoglobin concentration because extreme values predicted fewer livebirths and directional selection favoring higher oxygen saturation because higher values had more predicted livebirths. EPAS1, an oxygen homeostasis locus with strong signals of positive natural selection and a high frequency of variants occurring only among populations indigenous to the Tibetan Plateau, associated with hemoglobin concentration. High blood flow into the lungs, wide left ventricles, and low hypoxic heart rate responses aided effective convective oxygen transport to tissues. Women with physiologies closer to unstressed, low altitude values had the highest lifetime reproductive success. This example of ethnic Tibetan women residing at high altitudes in Nepal links reproductive fitness with trait combinations increasing oxygen delivery under severe hypoxic stress and demonstrates ongoing natural selection.

Effect of Tenofovir Alafenamide Fumarate on the outcomes of hospitalized COVID-19 patients: a prospective, block-balanced, open-label, randomized controlled trial

BackgroundThe global effort to cure COVID-19 is still ongoing. Thus, a prospective, block-balanced, open-label, randomized controlled trial was conducted to evaluate how Tenofovir Alafenamide Fumarate affects hospitalized COVID-19 patients’ outcomes.MethodsThe intervention and control groups of 60 hospitalized COVID-19 patients were randomly allocated. Along with normal medication, the intervention group received 25 mg of tenofovir orally daily for seven days. The control group got normal therapy, including remdesivir and corticosteroids. ICU hospitalization duration, laboratory data, fever, dyspnea, arterial blood oxygen saturation with and without an oxygen face mask, mechanical ventilation, and mortality were the outcomes.ResultsSixty of 236 eligible patients between September 2020 and February 2021 were enrolled. The intervention group had a mean age (±SD) of 61.33 (±13.09) years and the control group 60.03 (±18.03). Sixteen (53.3%) intervention patients and 15 (50.0%) control patients were males. The intervention group had fewer mechanical ventilation and ICU days. Tenofovir Alafenamide Fumarate did not improve fever, dyspnea, oxygen saturation with or without a face mask or nasal cannula, or laboratory data including WBC, ESR, CRP, AST, ALT, AlkP, total and direct bilirubin, in COVID-19 patients.ConclusionAccording to this pilot trial, Tenofovir Alafenamide Fumarate, along with conventional treatment, significantly reduced mechanical ventilation and ICU stay in COVID-19 patients. Further thorough research is necessary to verify this conclusion.

Predicting Survival Status in COVID-19 Patients: Machine Learning Models Development with Ventilator-Related and Biochemical Parameters from Early Stages: A Pilot Study.

Objective: Coronavirus disease 2019 (COVID-19) can cause intubation and ventilatory support due to respiratory failure, and extubation failure increases mortality risk. This study, therefore, aimed to explore the feasibility of using specific biochemical and ventilator parameters to predict survival status among COVID-19 patients by using machine learning. Methods: This study included COVID-19 patients from Taipei Medical University-affiliated hospitals from May 2021 to May 2022. Sequential data on specific biochemical and ventilator parameters from days 0-2, 3-5, and 6-7 were analyzed to explore differences between the surviving (successfully weaned off the ventilator) and non-surviving groups. These data were further used to establish separate survival prediction models using random forest (RF). Results: The surviving group exhibited significantly lower mean C-reactive protein (CRP) levels and mean potential of hydrogen ions levels (pH) levels on days 0-2 compared to the non-surviving group (CRP: non-surviving group: 13.16 ± 5.15 ng/mL, surviving group: 10.23 ± 5.15 ng/mL; pH: non-surviving group: 7.32 ± 0.07, survival group: 7.37 ± 0.07). Regarding the survival prediction performanace, the RF model trained solely with data from days 0-2 outperformed models trained with data from days 3-5 and 6-7. Subsequently, CRP, the partial pressure of carbon dioxide in arterial blood (PaCO2), pH, and the arterial oxygen partial pressure to fractional inspired oxygen (P/F) ratio served as primary indicators in survival prediction in the day 0-2 model. Conclusions: The present developed models confirmed that early biochemical and ventilatory parameters-specifically, CRP levels, pH, PaCO2, and P/F ratio-were key predictors of survival for COVID-19 patients. Assessed during the initial two days, these indicators effectively predicted the likelihood of successful weaning of from ventilators, emphasizing their importance in early management and improved outcomes in COVID-19-related respiratory failure.

Pilot study for non-invasive diabetes detection through classification of photoplethysmography signals using convolutional neural networks

Diabetes is a chronic disorder affecting vascular health, often altering pulse wave characteristics. Traditional pulse wave analysis (PWA) methods face challenges such as variability and complexity of signals. This study aims to overcome these limitations by leveraging deep learning models for more accurate and efficient classification. The methodology used in this study involves four key steps: data collection, data preprocessing, Convolutional Neural Network (CNN) model development, and model evaluation. Primary data were collected using a multipara patient monitor, including finger photoplethysmography (PPG) signals, blood pressure, mean arterial pressure, oxygen saturation, and pulse rate. Single pulse wave cycles from 60 healthy individuals and 60 patients with type 2 diabetes underwent preprocessing. The CNN model was trained using 50 PPG images from each group and achieved a training accuracy of 92%. The prediction capability of the model was evaluated using 20 unseen images, comprising 10 healthy and 10 diabetes PPG images. It attained a 90% overall test accuracy in distinguishing between PPG images of individuals with diabetes and those who are healthy. These findings suggest that CNN-based analysis of PPG signals provides a precise, non-invasive tool for diabetes screening. To further enhance accuracy, future studies should focus on increasing the dataset size and performing hyperparameter tuning to optimize the CNN model.

Comparing the Effect of Granisetron with Meperidine on Post-Shivering in Elective Cesarean Section under Spinal Anesthesia

Background: Post-operative shivering after spinal anesthesia is a common issue in women undergoing cesarean section, then its management is necessary to increase patients’ satisfaction. Therefore, the current study aimed to compare the prophylactic effect of Granisetron and meperidine on post-spinal shivering in elective cesarean section. Methods: In this double-blinded clinical trial study, 100 women under elective cesarean section using block randomization were divided into two groups. The spinal anesthesia was performed in all women with 10 mg hyperbaric bupivacaine 0.5 %. Then, after the birth of the baby, the patients received 0.04 mg/kg Granisetron or 0.4 mg/kg meperidine intravenously. Mean Arterial Pressure (MAP), Heart Rate (HR), and percentage of arterial blood oxygen saturation (SpO2) were measured before intervention and 60 minutes after surgery using a standard monitoring device. Shivering was evaluated 30 minutes after the surgery in the recovery room according to the clinical examinations. Results: The changes in hemodynamics parameters were similar between the two groups. There was a statistically significant difference in the rate of shivering between the two groups. The rate of shivering in the Granisetron group was higher than in the meperidine group. Thus, 13 patients (26%) and 5 patients (10%) had shivering in the Granisetron and meperidine groups, respectively (p=0.037). Conclusion: Granisetron was not more effective than meperidine as routine treatment in preventing shivering after spinal anesthesia in women under elective cesarean section.

The application effect of a pulmonary rehabilitation program based on empowerment theory for patients with COPD combined with heart failure.

Chronic obstructive pulmonary disease (COPD) and heart failure are often coexisting conditions that can severely impact patients' cardiopulmonary function and quality of life. Pulmonary rehabilitation programs, particularly those based on empowerment theory, may improve clinical outcomes by enhancing self-efficacy and promoting patient engagement. A total of 70 patients with COPD and heart failure admitted to our hospital's respiratory department from January 1, 2023, to April 31, 2024, were randomly assigned to either a control group (n = 35) or an observation group (n = 35). The control group received routine care, while the observation group underwent an empowerment-based pulmonary rehabilitation program in addition to routine care for 4 weeks. Lung function (forced vital capacity, forced expiratory volume in 1 second, maximum voluntary ventilation), arterial blood gas levels (partial pressure of carbon dioxide, partial pressure of oxygen, and arterial oxygen saturation), cardiac function (left ventricular ejection fraction and serum brain natriuretic peptide), cardiopulmonary function (heart rate, respiratory rate, and 6-minute walk test), self-efficacy, and rehabilitation compliance were measured before and after the intervention. There were no significant differences between the groups before the intervention (P > 0.05). After the intervention, the observation group exhibited significant improvements in lung function, arterial blood gas levels, cardiac and cardiopulmonary function, and self-efficacy scores compared with the control group (P < 0.05). Rehabilitation compliance was also significantly higher in the observation group (P < 0.05). An empowerment-based pulmonary rehabilitation program effectively improves rehabilitation compliance, lung and heart function, and self-efficacy in COPD patients with heart failure, suggesting it has strong potential for clinical application.

Plasma Volume Shifts and Acid–Base Balance After a Single Bout of Resistance Training

Abstract Purpose Changes in plasma volume (PV), acid–base status and ventilation have rarely been investigated in relation to resistance training (RT). This study aimed to investigate the effect of a single set of exhaustive leg press exercise on these basic physiological parameters in an integrated manner. Methods Twenty-seven male individuals (27.1 ± 4.1 years, 1.82 ± 0.62 m, 84.4 ± 12.5 kg, BMI: 25.4 ± 3.0 k/gm2) performed a single set leg press exercise during which hemoglobin concentration ([Hb]), hematocrit (Hct), pH, oxygen (pO2) and carbon dioxide partial pressures (pCO2), hydrogen carbonate concentration ([HCO3−]), standard base excess (SBE) and lactate concentration ([La−]) were determined. Total buffer capacity was calculated based on pH, [HCO3−] and pCO2. Results Mean PV decreased by 559 ± 230 mL (13.7%). As a result, arterial oxygen content was significantly increased due to hemoconcentration (P &lt; 0.001). At exhaustion, pH (7.30 ± 0.06), [HCO3−] (18.6 ± 2.0 mmol/L) and SBE (− 6.6 ± 2.4 mmol/L) were all significantly decreased (P &lt; 0.0001). The pCO2 first remained unchanged (39.4 ± 4.3 mm Hg) but demonstrated a significant decrease one-minute post-exercise (34.4 ± 4.2 mmHg), indicating metabolic acidosis with respiratory compensation, which was maintained until t+15. Non-bicarbonate buffering remained constant during recovery while the respiratory component steadily increased until 15-min post-exercise (50.2 mmol/L per pH). Conclusion PV shifts following a single set of leg press exercise improve post-exercise arterial oxygen content. The moderate metabolic acidosis was not compensated during exercise because of restricted breathing but partly compensated during the following 15-min recovery period. The respiratory compensation as part of the bicarbonate buffering made up 50% of total buffer capacity in the course of recovery.

Effects of acetazolamide on exercise performance in patients with COPD going to high altitude: randomised controlled trial

BackgroundIn patients with chronic obstructive pulmonary disease (COPD), preventive treatment with acetazolamide reduces adverse health effects during altitude travel. We investigated whether preventive acetazolamide treatment modifies exercise performance in COPD patients going to high altitude.MethodsIn this randomized, double-blind trial, lowlanders with COPD, FEV1 40–80%predicted, were assigned to acetazolamide (375 mg/24 h) or placebo treatment starting 24 h before ascent and while staying at 3100 m. Patients performed progressive cycling exercise to exhaustion at 760 m, before taking the study drug, and within 4 h after arrival at 3100 m. Primary outcome was the maximal power output (Wmax). ClinicalTrials.govNCT03177837.Results103 patients (32 women), mean ±sdage 57.2±8.1y, FEV1 66±11% predicted, were included in per protocol analyses. In 53 patients receiving acetazolamide, Wmax and oxygen uptake (V'O2max) at 760 m and 3100 m were 105±40 and 91±40watts, and 18.0±6.8 and 15.5±6.8 ml·min−1·kg−1(p&lt;0.001, both changes). Corresponding Wmax and V'O2max in 50 patients receiving placebo were 107±41 and 97±41watts, and 18.9±7.0 and 17.2±7.0 ml·min−1·kg−1(p&lt;0.001, both changes). Between-group differences (95%CI) in altitude-induced Wmax-changes were −3.0 watts (−8.7 to +2.7, p=0.305) and in V'O2max-changes were −0.8 ml·min−1·kg−1(−2.1 to +0.5, p=0.213). Acetazolamide mitigated the altitude-induced reduction of end-exercise PaO2by 0.7kPa (0.1 to 1.3, p=0.016). At 3100 m, maximal work rate with respiratory exchange ratio ≤1 was greater with acetazolamide than with placebo by 10.1 watts (4.0 to 16.2, p=0.022).ConclusionsIn lowlanders with COPD, preventive treatment with acetazolamide did not modify the altitude-induced reduction in maximal work rate. However, acetazolamide enhanced arterial oxygenation and submaximal, moderate-intensity work capacity compared to placebo.

Case-control study on risk factors for in-hospital mortality in patients with severe COVID-19.

The purpose of this study was to identify independent risk factors affecting patient survival and explore predictors of severe cases of coronavirus disease 2019 (COVID-19). We conducted a retrospective, observational, case-control study on adult patients with severe COVID-19 who were admitted to affiliated hospitals in Tianjin between December 18, 2022, and January 31, 2023. We used univariate and multifactorial logistic regression analyses to analyze demographic indicators, comorbidity profiles, and laboratory parameters in two groups of patients (deceased and surviving) to identify independent risk factors for death in patients with severe COVID-19. Patients in the deceased group were older than those in the survival group (p = 0.018), and there were more cases of coexisting respiratory insufficiency in the deceased group (p = 0.002). Additionally, laboratory test results for white blood cell count (WBC) and creatine kinase (CK) showed significantly higher values in the deceased group (p = 0.047 and p = 0.029, respectively), while arterial oxygen partial pressure (PAO2) showed significantly lower values compared to the survival group (p = 0.021). Age, respiratory insufficiency, WBCH (highest WBC value), CKH (highest CK value), and PAO2F (first PAO2 value) had area under curve (AUC) values of 0.698, 0.838, 0.721, 0.744, and 0.633, respectively. The main risk factors for mortality in patients with severe COVID-19 that we identified in this study were the advanced age of patients, coexisting respiratory insufficiency, elevated levels of WBC and CK, and decreased levels of PAO2. Elevated WBC and CK laboratory parameters, in particular, demonstrated good predictive value for in-hospital mortality risk.

Tachypnea in response to hypoxemia decreases with age in older patients.

To investigate if tachypneic response to hypoxia is decreased in older patients. We included all patients ≥65 years of age attending 52 Spanish emergency departments (EDs) for whom peripheral arterial oxygen saturation (SatO2) measured by pulsioxymetry and respiratory rate (RR) were registered at ED arrival. We assessed the relationship between SatO2 and RR in different models, and with the best-fitting model, we independently analyzed this relationship in four subgroups according to patient age (65-69, 70-79, 80-89, and ≥90 years). Five sensitivity analyses using different subsets of patients were carried out to check for the consistency of the results. We included 7126 patients, with medians for SatO2 and RR of 97% (interquartile range [IQR]: 94-98) and 15 bpm (IQR: 15-16), respectively. We found significant associations (P < 0.001) between SatO2 and RR in every model tested (P < 0.001 for all), with the quadratic model obtaining the best fit (R2: 0.098) over those obtained with linear (R2: 0.096) and logarithmic (R2: 0.092) models. The same was observed in sensitivity analyses, with R2 for quadratic models ranging from 0.069 in patients with low comorbidity and 0.102 in patients breathing room air. The mean RR for 100% SatO2 was 15 bpm and increased as SatO2 decreased, although with a progressive slowing of the slope, with a mean RR of 27 at 50% SatO2. We detected a decreased RR response to increasing hypoxemia according to age and, while the RR curve was higher and with a progressively steepening slope in the 972 patients aged 65-69 (mean RR of 42 bpm with 50% SatO2), a progressive slowing of slope was observed in the 2693 patients aged 70-79 (mean RR of 28 with 50% SatO2), the 2582 aged 80-89 (mean RR of 25) and the 879 aged ≥90 (mean RR of 23). Sensitivity analyses provided very similar results. Tachypneic response to hypoxemia in older patients decreases as age advances, regardless of the reason leading to hypoxemia. Geriatr Gerontol Int 2024; ••: ••-••.

The Effect of the Severity of Chronic Obstructive Pulmonary Disease on the Pituitary Gonadal Axis

This study aims to investigate the levels of anabolic hormone implicated in specific clinical symptoms of chronic obstructive pulmonary disease (COPD) in relation to disease severity. Sixty-four male patients with COPD for at least two years were included. COPD diagnosed was based on pulmonary function tests, with severity classified using the CAT score and mMRC breathlessness scale. Levels of various hormones including TSH T3 T4, FSH, LH, testesterone, prolactin, progesterone and CRP were measured. Arterial blood gases were also analyzed. Patients were categorized according to GOLD stages. LH, FSH levels decreased during exacerbation, with a significant positive correlation between LH and low arterial oxygen levels. lower testosterone levels were statistically significant in severe COPD patients with FEV1 &lt; 50%. A decrease in LH, testosterone FSH, TSH, progesterone and prolactin was observed with low blood oxygen levels, indicating dysfunction in the hypothalamic-pituitary-gonadal axis. However,stastistical significance varied.In conclusion, hormonal changes occur in male COPD patients, particulary related to disease severity. Testesterone levels correlate significantly with COPD severity. LH decrease during pronounced hypoxemia period was notable. Further research is necessary to evaluate the safety and efficacy of testosterone supplementation in COPD patients.

Associations of arterial oxygen partial pressure with all‑cause mortality in critically ill ischemic stroke patients: a retrospective cohort study from MIMIC IV 2.2

BackgroundAs a supportive treatment, the effectiveness of oxygen therapy in ischemic stroke (IS) patients remains unclear. This study aimed to evaluate the relationships between arterial partial pressure of oxygen (PaO2) and both consciousness at discharge and all-cause mortality risk in ICU IS patients.MethodsBlood gas measurements for all patients diagnosed with IS were extracted from the MIMIC-IV database. Patients were classified into four groups based on their average PaO2 during the first ICU day: hypoxemia (PaO2 < 80 mmHg), normoxemia (PaO2 80–120 mmHg), mild hyperoxemia (PaO2 121–199 mmHg), and moderate/severe hyperoxemia (PaO2 ≥ 200 mmHg). The primary endpoint was 90-day all-cause mortality. Secondary outcomes included the level of consciousness at discharge, assessed by the Glasgow Coma Scale (GCS), and 30-day all-cause mortality. Multivariate Cox regression and Restricted cubic spline (RCS) analysis were used to investigate the relationship between mean PaO2 and mortality, and to assess the nonlinear association between exposure and outcomes.ResultsThis study included a total of 946 IS patients. The cumulative incidence of 30-day and 90-day all-cause mortality increased with decreasing PaO2 levels. RCS analysis revealed a nonlinear relationship between PaO2 and the risk of 30-day all-cause mortality (nonlinear P < 0.0001, overall P < 0.0001), as well as a nonlinear association between PaO2 and 90-day all-cause mortality (nonlinear P < 0.0001, overall P < 0.0001). The results remained consistent after excluding the small subset of patients who received reperfusion therapy. Sensitivity analysis indicated that the favorable impact on survival tends to increase with the extended duration of elevated PaO2.ConclusionsFor IS patients who do not receive reperfusion therapy or whose recanalization status is unknown, a lower PaO2 early during ICU admission is considered an independent risk factor for short-term and recent mortality. Adjusting respiratory parameters to maintain supraphysiological levels of PaO2 appears to be beneficial for survival, although this finding requires further validation through additional studies.Trial registrationNot applicable.