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High Altitude Medicine & Biology Sep 2023Kharel, Sanjeev, Suraj Shrestha, Samriddha Raj Pant, Suman Acharya, Amit Sharma, Santosh Baniya, and Sanjeeb S. Bhandari. High-altitude exposure and cerebral venous... (Review)
Review
Kharel, Sanjeev, Suraj Shrestha, Samriddha Raj Pant, Suman Acharya, Amit Sharma, Santosh Baniya, and Sanjeeb S. Bhandari. High-altitude exposure and cerebral venous thrombosis: an updated systematic review. . 24:167-174, 2023. High altitude (HA) may increase the risk of cerebral venous thrombosis (CVT). Differentiating it from other HA illnesses is crucial for prompt treatment and better outcomes. We aimed to summarize the clinical data, etiology, and risk factors of this poorly understood entity at an HA. A systematic literature search of various databases, including PubMed, Embase, and Google Scholar, was done using relevant keywords; cerebral venous thrombosis; HA, up to May 1, 2022. A total of nine studies, including 75 cases of CVT at HA (3,000-8,848 m), with 66 males and 9 females, were included in this review. Headache and seizure were the most common clinical presentations. Smoking, drinking habits, and the use of oral contraceptive pills (OCP) were the most common risk factors for the development of CVT. Similarly, various underlying hypercoagulable states were also present among cases of CVT associated with HA exposure. Our review concludes that HA exposure can predispose individuals with risk factors such as preexisting hypercoagulable states, smoking, drinking habits, and use of OCP to an increased risk of CVT.
Topics: Female; Male; Humans; Altitude; Risk Factors; Smoking; Altitude Sickness; Venous Thrombosis
PubMed: 37615608
DOI: 10.1089/ham.2022.0106 -
Prevalence and risk factors of stroke in high-altitude areas: a systematic review and meta-analysis.BMJ Open Sep 2023The primary objective of this study is to investigate the prevalence and risk factors of stroke in high-altitude areas through a comprehensive systematic review and... (Meta-Analysis)
Meta-Analysis
OBJECTIVE
The primary objective of this study is to investigate the prevalence and risk factors of stroke in high-altitude areas through a comprehensive systematic review and meta-analysis.
DESIGN
This study adopts a systematic review and meta-analysis design.
DATA SOURCES
A thorough search was conducted on databases including PubMed, Web of Science, Embase, Cochrane Library, MEDLINE and SCOPUS, covering the period up to June 2023.
ELIGIBILITY CRITERIA
Studies reporting the prevalence of stroke in high-altitude areas and exploring related risk factors were included, regardless of whether they involved clinical samples or the general population. Studies with incomplete, outdated or duplicate data were excluded.
DATA EXTRACTION AND SYNTHESIS
We performed eligibility screening, data extraction and quality evaluation of the retrieved articles. Meta-analysis was employed to estimate the prevalence and risk factors of stroke in high-altitude areas. The Newcastle-Ottawa Scale was used to assess the risk of bias.
RESULTS
A total of 17 studies encompassing 8 566 042 participants from four continents were included, with altitudes ranging from 1500 m to nearly 5000 m. The pooled prevalence of stroke in high-altitude areas was found to be 0.5% (95% CI 0.3%-7%). Notably, the prevalence was higher in clinical samples (1.2%; 0.4%-2.5%) compared with the general population (0.3%; 95% CI 0.1%-0.6%). When considering geographic regions, the aggregated data indicated that stroke prevalence in the Eurasia plate was 0.3% (0.2%-0.4%), while in the American region, it was 0.8% (0.4%-1.3%). Age (OR, 14.891), gender (OR, 1.289), hypertension (OR, 3.158) and obesity (OR, 1.502) were identified as significant risk factors for stroke in high-altitude areas.
CONCLUSIONS
The findings of this study provide insights into the pooled prevalence of stroke in high-altitude areas, highlighting variations based on geographic regions and sampling type. Moreover, age, gender, hypertension and obesity were found to be associated with the occurrence of stroke.
PROSPERO REGISTRATION NUMBER
CRD42022381541.
Topics: Humans; Altitude; Prevalence; Risk Factors; Obesity; Hypertension; Stroke
PubMed: 37734891
DOI: 10.1136/bmjopen-2022-071433 -
Current Environmental Health Reports Dec 2023Environmental exposures have been associated with increased risk of cardiovascular mortality and acute coronary events, but their relationship with out-of-hospital... (Review)
Review
PURPOSE OF REVIEW
Environmental exposures have been associated with increased risk of cardiovascular mortality and acute coronary events, but their relationship with out-of-hospital cardiac arrest (OHCA) and sudden cardiac death (SCD) remains unclear. SCD is an important contributor to the global burden of cardiovascular disease worldwide.
RECENT FINDINGS
Current literature suggests a relationship between environmental exposures and cardiovascular disease, but their relationship with OHCA/SCD remains unclear. A literature search was conducted in PubMed, Embase, Web of Science, and Global Health. Of 5138 studies identified by our literature search, this review included 30 studies on air pollution, 42 studies on temperature, 6 studies on both air pollution and temperature, and 1 study on altitude exposure and OHCA/SCD. Particulate matter air pollution, ozone, and both hot and cold temperatures are associated with increased risk of OHCA/SCD. Pollution and other exposures related to climate change play an important role in OHCA/SCD incidence.
Topics: Humans; Temperature; Cross-Over Studies; Air Pollution; Particulate Matter; Death, Sudden, Cardiac; Out-of-Hospital Cardiac Arrest; Environmental Exposure; Air Pollutants
PubMed: 37845484
DOI: 10.1007/s40572-023-00414-7 -
Frontiers in Physiology 2023This study aimed to compare and rank the effect of hypoxic practices on maximum oxygen consumption (VOmax) in athletes and determine the hypoxic dose-response... (Review)
Review
This study aimed to compare and rank the effect of hypoxic practices on maximum oxygen consumption (VOmax) in athletes and determine the hypoxic dose-response correlation using network meta-analysis. The Web of Science, PubMed, EMBASE, and EBSCO databases were systematically search for randomized controlled trials on the effect of hypoxc interventions on the VOmax of athletes published from inception until 21 February 2023. Studies that used live-high train-high (LHTH), live-high train-low (LHTL), live-high, train-high/low (HHL), intermittent hypoxic training (IHT), and intermittent hypoxic exposure (IHE) interventions were primarily included. LHTL was further defined according to the type of hypoxic environment (natural and simulated) and the altitude of the training site (low altitude and sea level). A meta-analysis was conducted to determine the standardized mean difference between the effects of various hypoxic interventions on VOmax and dose-response correlation. Furthermore, the hypoxic dosage of the different interventions were coordinated using the "kilometer hour" model. From 2,072 originally identified titles, 59 studies were finally included in this study. After data pooling, LHTL, LHTH, and IHT outperformed normoxic training in improving the VOmax of athletes. According to the P-scores, LHTL combined with low altitude training was the most effective intervention for improving VOmax (natural: 0.92 and simulated: 0.86) and was better than LHTL combined with sea level training (0.56). A reasonable hypoxic dose range for LHTH (470-1,130 kmh) and HL (500-1,415 kmh) was reported with an inverted U-shaped curve relationship. Different types of hypoxic training compared with normoxic training serve as significant approaches for improving aerobic capacity in athletes. Regardless of the type of hypoxic training and the residential condition, LHTL with low altitude training was the most effective intervention. The characteristics of the dose-effect correlation of LHTH and LHTL may be associated with the negative effects of chronic hypoxia.
PubMed: 37745240
DOI: 10.3389/fphys.2023.1223037 -
Journal of Reproduction & Infertility 2023Cell-free fetal DNA (cffDNA) is a novel screening method for fetal aneuploidy that facilitated non-invasive prenatal testing (NIPT) through analysis of cffDNA in... (Review)
Review
BACKGROUND
Cell-free fetal DNA (cffDNA) is a novel screening method for fetal aneuploidy that facilitated non-invasive prenatal testing (NIPT) through analysis of cffDNA in maternal plasma. However, despite increased sensitivity, it has a number of limitations that may complicate of its results interpretation. Therefore, elucidating factors affecting fetal fraction, as a critical limitation, guides its clinical application.
METHODS
In this report, systematic search was carried out through PubMed, Web of Science, and Scopus databases until February 11, 2022 by using keywords consist of "noninvasive prenatal screening", "NIPT", "noninvasive prenatal", "cell free DNA" and "fetal fraction". The articles were screened for eligibility criteria before data extraction.
RESULTS
A total of 39 eligible studies, most published between 2010 and 2020, were included. Based on the results of studies, a negative correlation between maternal age and BMI/body weight with fetal fraction was found. Furthermore, LDL, cholesterol, triglyceride level, metformin, heparin and enoxaparin therapy, hemoglobin-related hemoglobinopathies, and physical activity showed to have negative associations. Interestingly, it seems the ethnicity of patients from South and East Asia has a correlation with fetal fraction compared to Caucasians. Positive correlation was observed between gestational age, free β-hCG, PAPP-A, living in high altitude, and twin pregnancy.
CONCLUSION
Considering each factor, there was significant inconsistency and controversy regarding their impact on outcomes. Indeed, multiple factors can influence the accuracy of NIPS results, and it is worth noting that the impact of these factors may vary depending on the individual's ethnic background. Therefore, it is important to recognize that NIPS remains a screening test, and comprehensive pre- and post-NIPS counseling should be conducted as part of standard clinical practice.
PubMed: 38164433
DOI: 10.18502/jri.v24i4.14149 -
American Journal of Physiology.... Nov 2023We conducted a systematic review and meta-analysis to determine the effect of acute poikilocapnic, high-altitude, and acute isocapnia hypoxemia on muscle sympathetic... (Meta-Analysis)
Meta-Analysis Review
We conducted a systematic review and meta-analysis to determine the effect of acute poikilocapnic, high-altitude, and acute isocapnia hypoxemia on muscle sympathetic nerve activity (MSNA) and cardiovascular function. A comprehensive search across electronic databases was performed until June 2021. All observational designs were included: population (healthy individuals); exposures (MSNA during hypoxemia); comparators (hypoxemia severity and duration); outcomes (MSNA; heart rate, HR; and mean arterial pressure, MAP). Sixty-one studies were included in the meta-analysis. MSNA burst frequency increased by a greater extent during high-altitude hypoxemia [ < 0.001; mean difference (MD), +22.5 bursts/min; confidence interval (CI) = -19.20 to 25.84] compared with acute poikilocapnic hypoxemia ( < 0.001; MD, +5.63 bursts/min; CI = -4.09 to 7.17) and isocapnic hypoxemia ( < 0.001; MD, +4.72 bursts/min; CI = -3.37 to 6.07). MSNA burst amplitude was only elevated during acute isocapnic hypoxemia ( = 0.03; standard MD, +0.46 au; CI = -0.03 to 0.90), and MSNA burst incidence was only elevated during high-altitude hypoxemia [ < 0.001; MD, 33.05 bursts/100 heartbeats; CI = -28.59 to 37.51]. Meta-regression analysis indicated a strong relationship between MSNA burst frequency and hypoxemia severity for acute isocapnic studies ( < 0.001) but not acute poikilocapnia ( = 0.098). HR increased by the same extent across each type of hypoxemia [ < 0.001; MD +13.81 heartbeats/min; 95% CI = 12.59-15.03]. MAP increased during high-altitude hypoxemia ( < 0.001; MD, +5.06 mmHg; CI = 3.14-6.99), and acute isocapnic hypoxemia ( < 0.001; MD, +1.91 mmHg; CI = 0.84-2.97), but not during acute poikilocapnic hypoxemia ( = 0.95). Both hypoxemia type and severity influenced sympathetic nerve and cardiovascular function. These data are important for the better understanding of healthy human adaptation to hypoxemia.
Topics: Humans; Muscle, Skeletal; Arterial Pressure; Hypoxia; Heart Rate; Sympathetic Nervous System; Blood Pressure
PubMed: 37642283
DOI: 10.1152/ajpregu.00021.2023 -
Heliyon Sep 2023With a growing number of athletes and coaches adopting altitude training, the importance for rationalizing and optimizing such training has been emphasized. We conducted...
PURPOSE
With a growing number of athletes and coaches adopting altitude training, the importance for rationalizing and optimizing such training has been emphasized. We conducted a meta-analysis to evaluate the influence of altitude training on athletes' aerobic capacity and to explore the best altitude training method to improve this capacity.
METHODS
We searched Web of Science, SpringerLink, Science Direct, EBSCO, and PubMed databases combined with manual search of the references to collect studies indexed from 1979 to September 2020 on the effect of altitude training on athletes' aerobic capacity. Data from experimental studies that reported hemoglobin levels and maximum oxygen uptake in athletes before and after altitude training, or in athletes performing altitude training in comparison with a control group were analyzed. Data of the populations, intervention, comparison, outcomes and study design were extracted. Review Manager software 5.3 was used for bias evaluation.
RESULTS
17 publications were included. In our meta-analysis, altitude training led to higher maximum oxygen uptake [standardized mean difference (SMD) = 0.67, 95% confidence interval (CI) 0.35-1.00, P < 0.001] and hemoglobin level (SMD = 0.50, 95% CI 0.11-0.90, P = 0.013) than training at lower altitude. The result of sensitivity analysis showed that results of meta-analysis were relatively stable, and there was no bias or change in the result of effect size according to the bias test. The results of subgroup analysis showed that high-altitude living and low-altitude training ("Hi-Lo" regime), with a training cycle of about three weeks at an altitude around 2500 m, had better effects than other regimes on the athletes' aerobic capacity.
CONCLUSIONS
Altitude training can improve athletes' aerobic capacity in terms of maximum oxygen uptake and hemoglobin level. Our results are limited by the number and quality of available studies. Therefore, more high-quality studies are needed to verify and extend these findings. Our study can provide scientific suggestions for the training of athletes.
PubMed: 37809554
DOI: 10.1016/j.heliyon.2023.e20188 -
High Altitude Medicine & Biology Mar 2024Poudel, Sangeeta, Sandesh Gautam, Purushottam Adhikari, and Ken Zafren. Physiological effects of sildenafil versus placebo at high altitude: a systematic review. .... (Review)
Review
Poudel, Sangeeta, Sandesh Gautam, Purushottam Adhikari, and Ken Zafren. Physiological effects of sildenafil versus placebo at high altitude: a systematic review. . 25:16-25, 2024. High altitude pulmonary edema (HAPE), a life-threatening condition that affects individuals ascending to high altitude, requires the development of pulmonary hypertension. Sildenafil can be used to prevent and treat HAPE, presumably by decreasing pulmonary artery pressure (PaP). We compared the physiological effects of sildenafil versus placebo at high altitude (above 2,500 m), including the effects on PaP. We performed a systematic search of PubMed, EMBASE, and Cochrane CENTRAL for randomized controlled studies of the physiological effects of sildenafil in hypoxia in healthy individuals. We conducted a systematic review of all studies meeting our criteria. Of the 14 studies that met the inclusion criteria, 8 were hypobaric hypoxia studies. Six studies reported data at rest at altitudes from 3,650 to 5,245 m. Two were simulations reporting exercise data at equivalent altitudes of 2,750-5,000 m. Nine studies used normobaric hypoxia corresponding to altitudes between 2,500 and 6,400 m. One reported only rest data, two reported rest and exercise data, and the others reported only exercise data. Sildenafil significantly reduced PaP at rest and exercise in hypobaric or normobaric hypoxia. There were no significant differences between arterial oxygen saturation (SpO) with sildenafil in hypobaric or normobaric hypoxia at rest or exercise. There were no significant differences in heart rate or mean arterial pressure (MAP) at rest or exercise and cardiac output during exercise in hypobaric or normobaric hypoxia. Sildenafil significantly reduces PaP at rest and exercise in normobaric or hypobaric hypoxia. Sildenafil has no significant effects on SpO, heart rate, cardiac output (during exercise), or MAP at rest or exercise in hypobaric or normobaric hypoxia.
Topics: Humans; Sildenafil Citrate; Altitude; Altitude Sickness; Hypoxia; Hypertension, Pulmonary
PubMed: 37751174
DOI: 10.1089/ham.2022.0043 -
International Journal of Sports... Aug 2023To identify the main training characteristics and competitive demands in women's road cycling.
PURPOSE
To identify the main training characteristics and competitive demands in women's road cycling.
METHODS
A systematic search was conducted on 5 databases according to PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analysis) guidelines. The articles had to be primary studies, written after 1990 with a sample of competitive women between the ages of 15 and 50. The Quality Assessment Tool for Quantitative Studies and the Oxford Levels of Evidence scales were used.
RESULTS
The search yielded 1713 articles, of which 20 were included. Studies on training and competitive demands (n = 5) found that both external and internal loads are higher in women than in men. Studies on strength and endurance training (n = 5) showed that both velocity-based and heavy-load strength training programs performed at least 2 days per week and including 3 to 4 lower-body exercises improved performance. Altitude-training studies (n = 3) found that "Live High-Train Low" was effective to increase performance during the first 9 days after the training camp. The 7 remaining studies focused on a range of topics. The methodological quality was strong for 12 studies and moderate for 8. In contrast, the level of evidence was high in 7 and low in the other 13.
CONCLUSIONS
Endurance training and competitive demands in women's road cycling are higher than those of men. Strength training is effective in women when the frequency, intensity, and number of exercises are appropriate, while altitude training should be completed a few days before competing. Further studies are warranted to better define the participants' competitive level, using a methodological design with a higher level of evidence.
Topics: Adolescent; Adult; Female; Humans; Male; Middle Aged; Young Adult; Bicycling; Databases, Factual; Endurance Training; Exercise; Resistance Training
PubMed: 37369364
DOI: 10.1123/ijspp.2023-0038 -
Infectious Diseases of Poverty Oct 2023Clonorchis sinensis, one of the most important food-borne zoonotic trematodes, remains prevalent in China. Understanding its infection status in animals is crucial for... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Clonorchis sinensis, one of the most important food-borne zoonotic trematodes, remains prevalent in China. Understanding its infection status in animals is crucial for controlling human clonorchiasis. Here we conducted a systematic review and meta-analysis to focus on the spatio-temporal disparities of C. sinensis infection in animals in China.
METHODS
Data on C. sinensis prevalence in snails, the second intermediate hosts, or animal reservoirs in China were extracted from electronic databases including PubMed, Embase, Web of Science, Chinese Wanfang database, CNKI, VIP, and China Biomedical Literature database. A random-effects meta-analysis model was utilized to estimate the pooled prevalence in each of the above animal hosts. Subgroup analysis and multivariable meta-regression were performed to explore potential sources of heterogeneity across studies and compare the temporal disparity of infection rates between high and low epidemic areas. Scatter plots were used to depict the biogeographical characteristics of regions reporting C. sinensis infection in animals.
RESULTS
The overall pooled prevalence of C. sinensis was 0.9% (95% CI: 0.6-1.2%) in snails, 14.2% (12.7-15.7%) in the second intermediate host, and 14.3% (11.4-17.6%) in animal reservoirs. Prevalence in low epidemic areas (with human prevalence < 1%) decreased from 0.6% (0.2-1.2%) before 1990 to 0.0% (0.0-3.6%) after 2010 in snails (P = 0.0499), from 20.3% (15.6-25.3%) to 8.8% (5.6-12.6%) in the second intermediate hosts (P = 0.0002), and from 18.3% (12.7-24.7%) to 4.7% (1.0-10.4%) in animal reservoirs. However, no similar decrease in prevalence was observed in high epidemic areas (with human prevalence ≥ 1.0%). C. sinensis infections were predominantly reported in areas with altitudes below 2346 m and annual cumulative precipitation above 345 mm and were mostly concentrated in eastern China.
CONCLUSIONS
There are spatio-temporal disparities in the animal infections of C. sinensis in different areas of China. Animal infections are primarily concentrated in regions with low altitude and high precipitation. The results suggest that implementing One Health-based comprehensive measures targeting both humans and animals, especially in high epidemic areas, is essential for successful eradication of C. sinensis in China.
Topics: Animals; Humans; Clonorchiasis; Clonorchis sinensis; China; Prevalence; Snails
PubMed: 37845775
DOI: 10.1186/s40249-023-01146-4