1
|
Forrer A, Gaisl T, Sevik A, Meyer M, Senteler L, Lichtblau M, Bloch KE, Ulrich S, Furian M. Partial Pressure of Arterial Oxygen in Healthy Adults at High Altitudes: A Systematic Review and Meta-Analysis. JAMA Netw Open 2023; 6:e2318036. [PMID: 37326993 PMCID: PMC10276310 DOI: 10.1001/jamanetworkopen.2023.18036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 04/27/2023] [Indexed: 06/17/2023] Open
Abstract
Importance With increasing altitude, the partial pressure of inspired oxygen decreases and, consequently, the Pao2 decreases. Even though this phenomenon is well known, the extent of the reduction as a function of altitude remains unknown. Objective To calculate an effect size estimate for the decrease in Pao2 with each kilometer of vertical gain among healthy unacclimatized adults and to identify factors associated with Pao2 at high altitude (HA). Data Sources A systematic search of PubMed and Embase was performed from database inception to April 11, 2023. Search terms included arterial blood gases and altitude. Study Selection A total of 53 peer-reviewed prospective studies in healthy adults providing results of arterial blood gas analysis at low altitude (<1500 m) and within the first 3 days at the target altitude (≥1500 m) were analyzed. Data Extraction and Synthesis Primary and secondary outcomes as well as study characteristics were extracted from the included studies, and individual participant data (IPD) were requested. Estimates were pooled using a random-effects DerSimonian-Laird model for the meta-analysis. Main Outcomes and Measures Mean effect size estimates and 95% CIs for reduction in Pao2 at HA and factors associated with Pao2 at HA in healthy adults. Results All of the 53 studies involving 777 adults (mean [SD] age, 36.2 [10.5] years; 510 men [65.6%]) reporting 115 group ascents to altitudes between 1524 m and 8730 m were included in the aggregated data analysis; 13 of those studies involving 305 individuals (mean [SD] age, 39.8 [13.6] years; 185 men [60.7%]) reporting 29 ascents were included in the IPD analysis. The estimated effect size of Pao2 was -1.60 kPa (95% CI, -1.73 to -1.47 kPa) for each 1000 m of altitude gain (τ2 = 0.14; I2 = 86%). The Pao2 estimation model based on IPD data revealed that target altitude (-1.53 kPa per 1000 m; 95% CI, -1.63 to -1.42 kPa per 1000 m), age (-0.01 kPa per year; 95% CI, -0.02 to -0.003 kPa per year), and time spent at an altitude of 1500 m or higher (0.16 kPa per day; 95% CI, 0.11-0.21 kPa per day) were significantly associated with Pao2. Conclusions and Relevance In this systematic review and meta-analysis, the mean decrease in Pao2 was 1.60 kPa per 1000 m of vertical ascent. This effect size estimate may improve the understanding of physiological mechanisms, assist in the clinical interpretation of acute altitude illness in healthy individuals, and serve as a reference for physicians counseling patients with cardiorespiratory disease who are traveling to HA regions.
Collapse
Affiliation(s)
- Aglaia Forrer
- Department of Respiratory Medicine, University Hospital Zurich, Zurich, Switzerland
| | - Thomas Gaisl
- Department of Respiratory Medicine, University Hospital Zurich, Zurich, Switzerland
- Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, Massachusetts
| | - Ahmet Sevik
- Department of Respiratory Medicine, University Hospital Zurich, Zurich, Switzerland
| | - Michelle Meyer
- Department of Respiratory Medicine, University Hospital Zurich, Zurich, Switzerland
| | - Luzi Senteler
- Department of Respiratory Medicine, University Hospital Zurich, Zurich, Switzerland
| | - Mona Lichtblau
- Department of Respiratory Medicine, University Hospital Zurich, Zurich, Switzerland
| | - Konrad Ernst Bloch
- Department of Respiratory Medicine, University Hospital Zurich, Zurich, Switzerland
- Swiss-Kyrgyz High-Altitude Medicine and Research Initiative, Zurich, Switzerland
| | - Silvia Ulrich
- Department of Respiratory Medicine, University Hospital Zurich, Zurich, Switzerland
- Swiss-Kyrgyz High-Altitude Medicine and Research Initiative, Zurich, Switzerland
| | - Michael Furian
- Department of Respiratory Medicine, University Hospital Zurich, Zurich, Switzerland
- Swiss-Kyrgyz High-Altitude Medicine and Research Initiative, Zurich, Switzerland
- Research Department, Swiss University for Traditional Chinese Medicine, Bad Zurzach, Switzerland
| |
Collapse
|
2
|
Furian M, Tannheimer M, Burtscher M. Effects of Acute Exposure and Acclimatization to High-Altitude on Oxygen Saturation and Related Cardiorespiratory Fitness in Health and Disease. J Clin Med 2022; 11:jcm11226699. [PMID: 36431176 PMCID: PMC9697047 DOI: 10.3390/jcm11226699] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Revised: 11/08/2022] [Accepted: 11/09/2022] [Indexed: 11/16/2022] Open
Abstract
Maximal values of aerobic power (VO2max) and peripheral oxygen saturation (SpO2max) decline in parallel with gain in altitude. Whereas this relationship has been well investigated when acutely exposed to high altitude, potential benefits of acclimatization on SpO2 and related VO2max in healthy and diseased individuals have been much less considered. Therefore, this narrative review was primarily aimed to identify relevant literature reporting altitude-dependent changes in determinants, in particular SpO2, of VO2max and effects of acclimatization in athletes, healthy non-athletes, and patients suffering from cardiovascular, respiratory and/or metabolic diseases. Moreover, focus was set on potential differences with regard to baseline exercise performance, age and sex. Main findings of this review emphasize the close association between individual SpO2 and VO2max, and demonstrate similar altitude effects (acute and during acclimatization) in healthy people and those suffering from cardiovascular and metabolic diseases. However, in patients with ventilatory constrains, i.e., chronic obstructive pulmonary disease, steep decline in SpO2 and V̇O2max and reduced potential to acclimatize stress the already low exercise performance. Finally, implications for prevention and therapy are briefly discussed.
Collapse
Affiliation(s)
- Michael Furian
- Pulmonary Division, University Hospital Zurich, 8092 Zurich, Switzerland
- Research Department, Swiss University of Traditional Chinese Medicine, 5330 Bad Zurzach, Switzerland
| | - Markus Tannheimer
- Department of Sport and Rehabilitation Medicine, University of Ulm, 89075 Ulm, Germany
| | - Martin Burtscher
- Department of Sport Science, University of Innsbruck, 6020 Innsbruck, Austria
- Correspondence:
| |
Collapse
|
3
|
Fan X, He M, Tong C, Nie X, Zhong Y, Lu M. Development and Comparison of Predictive Models Based on Different Types of Influencing Factors to Select the Best One for the Prediction of OSAHS Prevalence. Front Psychiatry 2022; 13:892737. [PMID: 35923456 PMCID: PMC9340571 DOI: 10.3389/fpsyt.2022.892737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 05/02/2022] [Indexed: 11/28/2022] Open
Abstract
OBJECTIVE This study aims to retrospectively analyze numerous related clinical data to identify three types of potential influencing factors of obstructive sleep apnea-hypopnea syndrome (OSAHS) for establishing three predictive nomograms, respectively. The best performing one was screened to guide further clinical decision-making. METHODS Correlation, difference and univariate logistic regression analysis were used to identify the influencing factors of OSAHS. Then these factors are divided into three different types according to the characteristics of the data. Lasso regression was used to filter out three types of factors to construct three nomograms, respectively. Compare the performance of the three nomograms evaluated by C-index, ROC curve and Decision Curve Analysis to select the best one. Two queues were obtained by randomly splitting the whole queue, and similar methods are used to verify the performance of the best nomogram. RESULTS In total, 8 influencing factors of OSAHS have been identified and divided into three types. Lasso regression finally determined 6, 3 and 4 factors to construct mixed factors nomogram (MFN), baseline factors nomogram (BAFN) and blood factors nomogram (BLFN), respectively. MFN performed best among the three and also performed well in multiple queues. CONCLUSION Compared with BAFN and BLFN constructed by single-type factors, MFN constructed by six mixed-type factors shows better performance in predicting the risk of OSAHS.
Collapse
Affiliation(s)
- Xin Fan
- Department of Emergency, Shangrao Hospital Affiliated to Nanchang University, Shangrao People's Hospital, Shangrao, China.,Department of Otolaryngology-Head and Neck Surgery, The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Mu He
- School of Stomatology, Nanchang University, Nanchang, China
| | - Chang Tong
- Pediatric Medical School, Nanchang University, Nanchang, China
| | - Xiyi Nie
- Department of Neurosurgery, Yichun People's Hospital, Yichun, China
| | - Yun Zhong
- The First Clinical Medical College of Nanchang University, Nanchang, China
| | - Min Lu
- Department of Emergency, Shangrao Hospital Affiliated to Nanchang University, Shangrao People's Hospital, Shangrao, China
| |
Collapse
|
4
|
Wang S, Wei Y, Hu C, Liu F. Proteomic analysis reveals proteins and pathways associated with declined testosterone production in male obese mice after chronic high-altitude exposure. Front Endocrinol (Lausanne) 2022; 13:1046901. [PMID: 36531490 PMCID: PMC9748565 DOI: 10.3389/fendo.2022.1046901] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Accepted: 11/10/2022] [Indexed: 12/05/2022] Open
Abstract
OBJECTIVE Obesity is common in highland areas owing to lifestyle alterations. There are pieces of evidence to suggest that both obesity and hypoxia may promote oxidative stress, leading to hypogonadism in males. These findings indicate an increased risk of hypogonadism in obese males following hypoxia exposure. However, the mechanisms underlying the disease process remain unclear. The current study aims to explore the mechanism of testosterone production dysfunction in obese male mice exposed to a chronic high-altitude hypoxia environment. METHODS An obese male mouse model was generated by inducing obesity in mice via a high-fat diet for 14 weeks, and the obese mice were then exposed to a high-altitude hypoxia environment for 24 days. Sera and testicular tissues were collected to detect serum lipids, sex hormone level, and testicular oxidative stress indicators. Morphological examination was performed to assess pathological alterations in testicular tissues and suborganelles in leydig cells. Proteomic alterations in testicular tissues were investigated using quantitative proteomics in Obese/Control and Obese-Hypoxia/Obese groups. RESULTS The results showed that chronic high-altitude hypoxia exposure aggravated low testosterone production in obese male mice accompanied by increased testicular oxidative stress and histological damages. In total, 363 and 242 differentially expressed proteins (DEPs) were identified in the two comparison groups, Obese/Control and Obese-Hypoxia/Obese, respectively. Functional enrichment analysis demonstrated that several significant functional terms and pathways related to testosterone production were altered in the two comparison groups. These included cholesterol metabolism, steroid hormone biosynthesis, peroxisome proliferator-activated receptor (PPAR) signaling pathway, oxidative stress responses, as well as retinol metabolism. Finally, 10 representative DEPs were selected for parallel reaction monitoring verification. Among them, StAR, DHCR7, NSDHL, CYP51A1, FDPS, FDX1, CYP11A1, ALDH1A1, and GPX3 were confirmed to be downregulated in the two groups. CONCLUSIONS Chronic hypoxia exposure could exacerbate low testosterone production in obese male mice by influencing the expression of key proteins involved in steroid hormone biosynthesis, cholesterol biosynthesis, oxidative stress responses and retinol metabolism.
Collapse
Affiliation(s)
- Shuqiong Wang
- Research Center for High Altitude Medicine, Qinghai University, Xining, China
- Key Laboratory of High Altitude Medicine, Ministry of Education, Xining, China
- Key Laboratory of Application and Foundation for High Altitude Medicine Research in Qinghai Province, Qinghai-Utah Joint Research Key Lab for High Altitude Medicine, Xining, China
- Department of Endocrinology, Qinghai Provincial People’s Hospital, Xining, China
| | - Youwen Wei
- Department of Plague Prevention and Control, Qinghai Institute for Endemic Disease Prevention and Control, Xining, China
| | - Caiyan Hu
- Department of Laboratory Medicine, Baoding First Central Hospital, Baoding, China
| | - Fang Liu
- Department of Biochemistry, Medical College, Qinghai University, Xining, China
- *Correspondence: Fang Liu,
| |
Collapse
|
5
|
Wang X, Luo J, Huang R, Xiao Y. The Elevated Central Chemosensitivity in Obstructive Sleep Apnea Patients with Hypertension. Nat Sci Sleep 2022; 14:855-865. [PMID: 35547180 PMCID: PMC9081185 DOI: 10.2147/nss.s362319] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 04/20/2022] [Indexed: 11/25/2022] Open
Abstract
PURPOSE Hypertension is a common comorbidity in obstructive sleep apnea (OSA), in which dysfunction of the autonomic nervous system plays an integral part. Chemoreflex is essential for ventilatory control and cardiovascular activity. This study aimed to determine whether central chemosensitivity was increased in OSA patients with hypertension and the potential role of the autonomic nerve activity in this relationship. PATIENTS AND METHODS A total of 77 men with OSA were included in this cross-sectional study. We measured hypercapnic ventilatory response (HCVR) by the rebreathing method under isoxic hyperoxia to test the central ventilatory chemosensitivity since hyperoxia silences the peripheral chemoreceptors' response to CO2. To elevate the autonomic nerve activity, time-domain, frequency-domain, and non-linear variables of heart rate variability were calculated over 5-min records. Univariate and multivariate linear regression analyses were used to find the determinants of HCVR. RESULTS The median HCVR was 2.3 (1.8, 3.3), 2.1 (1.6, 3.0), and 3 (2.2, 3.7) L/min/mmHg in all participants, OSA patients, and OSA patients with hypertension, respectively. Hypertension was significantly associated with elevated HCVR after adjusting for age, central obesity, OSA severity, daytime sleepiness, and diabetes mellitus. Compared with OSA patients, OSA patients with hypertension had higher body mass index, worse nocturnal hypoxia, and lower time-domain variables and frequency-domain variables. After adjusting for age, apnea-hypopnea index, central obesity, and beta-blocker usage, approximate entropy was independently negatively associated with HCVR in OSA patients with hypertension. CONCLUSION This study demonstrated elevated central chemosensitivity in OSA patients with hypertension. Compared with OSA patients, OSA patients with hypertension had attenuated parasympathetic nerve activity. This study preliminarily illustrated that elevated central chemosensitivity might be associated with weak adaptability of the cardiac autonomic nervous system in OSA patients with hypertension.
Collapse
Affiliation(s)
- Xiaona Wang
- Department of Respiratory and Critical Care Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China
| | - Jinmei Luo
- Department of Respiratory and Critical Care Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China
| | - Rong Huang
- Department of Respiratory and Critical Care Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China
| | - Yi Xiao
- Department of Respiratory and Critical Care Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China
| |
Collapse
|
6
|
Sainju RK, Dragon DN, Winnike HB, Ten Eyck P, Granner MA, Gehlbach BK, Richerson GB. Hypercapnic ventilatory response in epilepsy patients treated with VNS: A case-control study. Epilepsia 2021; 62:e140-e146. [PMID: 34265074 PMCID: PMC9113047 DOI: 10.1111/epi.16997] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 06/23/2021] [Accepted: 06/23/2021] [Indexed: 11/29/2022]
Abstract
OBJECTIVE Central CO2 chemoreception (CCR), a major chemical drive for breathing, can be quantified with a CO2 re-breathing test to measure the hypercapnic ventilatory response (HCVR). An attenuated HCVR correlates with the severity of respiratory dysfunction after generalized convulsive seizures and is a potential biomarker for sudden unexpected death in epilepsy (SUDEP) risk. Vagus nerve stimulation (VNS) may reduce SUDEP risk, but for unclear reasons the risk remains higher during the first 2 years after implantation. The vagus nerve has widespread connections in the brainstem, including key areas related to CCR. Here we examined whether chronic electrical stimulation of the vagus nerve induces changes in CCR. METHODS We compared the HCVR in epilepsy patients with or without an active VNS in a sex- and age-matched case-control study. Eligible subjects were selected from a cohort of patients who previously underwent HCVR testing. The HCVR slope, change in minute ventilation (VE) with respect to change in end tidal (ET) CO2 (∆ VE/ ∆ ETCO2) during the test was calculated for each subject. Key variables were compared between the two groups. Univariate and multivariate analyses were carried out for HCVR slope as dependent variable. RESULTS A total of 86 subjects were in the study. HCVR slope was significantly lower in the cases compared to the controls. Cases had longer duration of epilepsy and higher number of anti-epileptic drugs (AEDs) tried during lifetime. Having active VNS and ETCO2 were associated with a low HCVR slope while high BMI was associated with high HCVR slope in both univariate and multivariate analyses. DISCUSSION We found having an active VNS was associated with relatively attenuated HCVR slope. Although duration of epilepsy and number of AEDs tried during lifetime was significantly different between the groups, they were not predictors of HCVR slope in subsequent analysis. CONCLUSION Chronic electrical stimulation of the vagus nerve by VNS may be associated with an attenuated CCR [Correction added on 24 November 2021, after first online publication: The preceding sentence has been revised from “Chronic electrical stimulation of VNS nerve by VNS…”]. A larger prospective study may help to establish the time course of this effect in relation to the time of VNS implantation, whether there is a causal relationship, and determine how it affects SUDEP risk.
Collapse
Affiliation(s)
- Rup K Sainju
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Deidre N Dragon
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Harold B Winnike
- Institute for Clinical and Translational Science, University of Iowa, Iowa City, IA, USA
| | - Patrick Ten Eyck
- Institute for Clinical and Translational Science, University of Iowa, Iowa City, IA, USA
| | - Mark A Granner
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Brian K Gehlbach
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - George B Richerson
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
- Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
- Veterans Affairs Medical Center, Iowa City, IA, USA
| |
Collapse
|
7
|
Hypoxic Exercise Exacerbates Hypoxemia and Acute Mountain Sickness in Obesity: A Case Analysis. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph18179078. [PMID: 34501667 PMCID: PMC8430682 DOI: 10.3390/ijerph18179078] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Revised: 08/14/2021] [Accepted: 08/23/2021] [Indexed: 12/21/2022]
Abstract
Acute mountain sickness (AMS) is a common syndrome characterized by headache, dizziness, loss of appetite, weakness, and nausea. As a major public health issue, obesity has increased in high altitude urban residents and intermittent commuters to high altitudes. The present study investigated acute hypoxic exposure and hypoxic exercise on hypoxemia severity and AMS symptoms in a physically active obese man. In this case analysis, peripheral oxygen saturation (SpO2) was used to evaluate hypoxemia, heart rate (HR) and blood pressure (BP) were used to reflect the function of autonomic nervous system (ANS), and Lake Louise scoring (LLS) was used to assess AMS. The results showed that acute hypoxic exposure led to severe hypoxemia (SpO2 = 72%) and tachycardia (HRrest = 97 bpm), and acute hypoxic exercise exacerbated severe hypoxemia (SpO2 = 59%) and ANS dysfunction (HRpeak = 167 bpm, SBP/DBP = 210/97 mmHg). At the end of the 6-h acute hypoxic exposure, the case developed severe AMS (LLS = 10) symptoms of headache, gastrointestinal distress, cyanosis, vomiting, poor appetite, and fatigue. The findings of the case study suggest that high physical activity level appears did not show a reliable protective effect against severe hypoxemia, ANS dysfunction, and severe AMS symptoms in acute hypoxia exposure and hypoxia exercise.
Collapse
|
8
|
Siques P, Brito J, Ordenes S, Pena E. Involvement of overweight and lipid metabolism in the development of pulmonary hypertension under conditions of chronic intermittent hypoxia. Pulm Circ 2020; 10:42-49. [PMID: 33110496 PMCID: PMC7557786 DOI: 10.1177/2045894020930626] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 05/04/2020] [Indexed: 12/12/2022] Open
Abstract
There is growing evidence that exposure to hypoxia, regardless of the source,
elicits several metabolic responses in individuals. These responses are
constitutive and are usually observed under hypoxia but vary according to the
type of exposure. The aim of this review was to describe the involvement of
obesity and lipid metabolism in the development of high-altitude pulmonary
hypertension and in the development of acute mountain sickness under chronic
intermittent hypoxia. Overweight or obesity, which are common in individuals
with long-term chronic intermittent hypoxia exposure (high-altitude miners,
shift workers, and soldiers), are thought to play a major role in the
development of acute mountain sickness and high-altitude pulmonary hypertension.
This association may be rooted in the interactions between obesity-related
metabolic and physical alterations, such as increased waist circumference and
neck circumference, among others, which lead to critical ventilation
impairments; these impairments aggravate hypoxemia at high altitude, thereby
triggering high-altitude diseases. Overweight and obesity are strongly
associated with higher mean pulmonary artery pressure in the context of
long-term chronic intermittent hypoxia. Remarkably, de novo synthesis of
triglycerides by the sterol regulatory element-binding protein-1c pathway has
been demonstrated, mainly due to the upregulation of stearoyl-CoA desaturase-1,
which is also associated with the same outcomes. Therefore, overweight, obesity,
and other metabolic conditions may hinder proper acclimatization. The involved
mechanisms include respiratory impairment, alteration of the nitric oxide
pathways, inflammatory status, reactive oxygen species imbalance, and other
metabolic changes; however, further studies are required.
Collapse
Affiliation(s)
- Patricia Siques
- Institute of Health Studies, Universidad Arturo Prat, Iquique, Chile.,Institute DECIPHER, German-Chilean Institute for Research on Pulmonary Hypoxia and its Health Sequelae, Iquique (Chile)
| | - Julio Brito
- Institute of Health Studies, Universidad Arturo Prat, Iquique, Chile.,Institute DECIPHER, German-Chilean Institute for Research on Pulmonary Hypoxia and its Health Sequelae, Iquique (Chile)
| | - Stefany Ordenes
- Institute of Health Studies, Universidad Arturo Prat, Iquique, Chile.,Institute DECIPHER, German-Chilean Institute for Research on Pulmonary Hypoxia and its Health Sequelae, Iquique (Chile)
| | - Eduardo Pena
- Institute of Health Studies, Universidad Arturo Prat, Iquique, Chile.,Institute DECIPHER, German-Chilean Institute for Research on Pulmonary Hypoxia and its Health Sequelae, Iquique (Chile)
| |
Collapse
|
9
|
Framnes SN, Arble DM. The Bidirectional Relationship Between Obstructive Sleep Apnea and Metabolic Disease. Front Endocrinol (Lausanne) 2018; 9:440. [PMID: 30127766 PMCID: PMC6087747 DOI: 10.3389/fendo.2018.00440] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 07/17/2018] [Indexed: 12/22/2022] Open
Abstract
Obstructive sleep apnea (OSA) is a common sleep disorder, effecting 17% of the total population and 40-70% of the obese population (1, 2). Multiple studies have identified OSA as a critical risk factor for the development of obesity, diabetes, and cardiovascular diseases (3-5). Moreover, emerging evidence indicates that metabolic disorders can exacerbate OSA, creating a bidirectional relationship between OSA and metabolic physiology. In this review, we explore the relationship between glycemic control, insulin, and leptin as both contributing factors and products of OSA. We conclude that while insulin and leptin action may contribute to the development of OSA, further research is required to determine the mechanistic actions and relative contributions independent of body weight. In addition to increasing our understanding of the etiology, further research into the physiological mechanisms underlying OSA can lead to the development of improved treatment options for individuals with OSA.
Collapse
Affiliation(s)
| | - Deanna M. Arble
- Department of Biological Sciences, Marquette University, Milwaukee, WI, United States
| |
Collapse
|
10
|
San Martin R, Brito J, Siques P, León-Velarde F. Obesity as a Conditioning Factor for High-Altitude Diseases. Obes Facts 2017; 10:363-372. [PMID: 28810235 PMCID: PMC5644942 DOI: 10.1159/000477461] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 05/10/2017] [Indexed: 12/19/2022] Open
Abstract
Obesity, a worldwide epidemic, has become a major health burden because it is usually accompanied by an increased risk for insulin resistance, diabetes, hypertension, cardiovascular diseases, and even some kinds of cancer. It also results in associated increases in healthcare expenditures and labor and economic consequences. There are also other fields of medicine and biology where obesity or being overweight play a major role, such as high-altitude illnesses (acute mountain sickness, hypoxic pulmonary hypertension, and chronic mountain sickness), where an increasing relationship among these two morbid statuses has been demonstrated. This association could be rooted in the interactions between obesity-related metabolic alterations and critical ventilation impairments due to obesity, which would aggravate hypobaric hypoxia at high altitudes, leading to hypoxemia, which is a trigger for developing high-altitude diseases. This review examines the current literature to support the idea that obesity or overweight could be major conditioning factors at high altitude.
Collapse
Affiliation(s)
- Rocío San Martin
- Institute of Health Studies, Universidad Arturo Prat, Iquique, Chile
| | - Julio Brito
- Institute of Health Studies, Universidad Arturo Prat, Iquique, Chile
- *Julio Brito, Institute of Health Studies, Universidad Arturo Prat, Avda. Arturo Prat 2120, Iquique, 1110939, Chile,
| | - Patricia Siques
- Institute of Health Studies, Universidad Arturo Prat, Iquique, Chile
| | - Fabiola León-Velarde
- Department of Biological and Physiological Sciences. Facultad de Ciencias y Filosofía/ IIA, Universidad Peruana Cayetano Heredia, Lima, Perú
| |
Collapse
|
11
|
Paleczny B, Siennicka A, Zacharski M, Jankowska EA, Ponikowska B, Ponikowski P. Increased body fat is associated with potentiation of blood pressure response to hypoxia in healthy men: relations with insulin and leptin. Clin Auton Res 2016; 26:107-16. [PMID: 26781642 PMCID: PMC4819928 DOI: 10.1007/s10286-015-0338-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 12/16/2015] [Indexed: 12/18/2022]
Abstract
Background Increased peripheral chemosensitivity (PChS) has been proposed
as mechanism underlying obesity-related sympathoactivation, with insulin and/or leptin as possible mediators. However, human data on PChS in obesity are scarce. Therefore, we explored this issue in a sample of 41 healthy men aged 30–59 years, divided according to body fat percentage (fat %) into two groups: <25 and ≥25 %. Methods PChS was assessed using transient hypoxia method [respiratory (PChS-MV), heart rate (PChS-HR), and blood pressure (PChS-SBP) responses were calculated]. Baroreflex sensitivity (BRS-Seq) was assessed using sequence method. Fasting plasma insulin and leptin levels were measured. Homeostatic model assessment (HOMA) was used to assess insulin sensitivity/resistance. Results Individuals with ≥25 % body fat demonstrated increased PChS-SBP (p < 0.01), but unchanged PChS-MV and PChS-HR (both p > 0.4). PChS-SBP was related positively with anthropometric characteristics (e.g. waist circumference, fat %), plasma insulin and HOMA (all p < 0.05), and negatively with BRS-Seq (p = 0.001), but not with plasma leptin (p = 0.27). Conclusions In healthy men, overweight/obesity is accompanied by augmented blood pressure response from peripheral chemoreceptors, while respiratory and heart rate responses remain unaltered. Hyperinsulinaemia and insulin resistance (but not hyperleptinaemia) are associated with augmented pressure response from chemoreceptors. Electronic supplementary material The online version of this article (doi:10.1007/s10286-015-0338-2) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Bartłomiej Paleczny
- Department of Physiology, Wroclaw Medical University, ul. Chałubińskiego 10, 50-368, Wroclaw, Poland. .,Department of Cardiology, Centre for Heart Diseases, 4th Military Hospital, Wroclaw, Poland.
| | - Agnieszka Siennicka
- Department of Physiology, Wroclaw Medical University, ul. Chałubińskiego 10, 50-368, Wroclaw, Poland.,Department of Cardiology, Centre for Heart Diseases, 4th Military Hospital, Wroclaw, Poland
| | - Maciej Zacharski
- Department of Biochemistry, Pharmacology and Toxicology, Wroclaw University of Environmental and Life Sciences, Wroclaw, Poland
| | - Ewa Anita Jankowska
- Department of Cardiology, Centre for Heart Diseases, 4th Military Hospital, Wroclaw, Poland.,Laboratory for Applied Research on Cardiovascular System, Department of Heart Diseases, Wroclaw Medical University, Wroclaw, Poland
| | - Beata Ponikowska
- Department of Physiology, Wroclaw Medical University, ul. Chałubińskiego 10, 50-368, Wroclaw, Poland
| | - Piotr Ponikowski
- Department of Cardiology, Centre for Heart Diseases, 4th Military Hospital, Wroclaw, Poland.,Department of Heart Diseases, Wroclaw Medical University, Wroclaw, Poland
| |
Collapse
|
12
|
Edgell H, McMurtry MS, Haykowsky MJ, Paterson I, Ezekowitz JA, Dyck JRB, Stickland MK. Peripheral chemoreceptor control of cardiovascular function at rest and during exercise in heart failure patients. J Appl Physiol (1985) 2015; 118:839-48. [PMID: 25614600 DOI: 10.1152/japplphysiol.00898.2014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 01/20/2015] [Indexed: 01/01/2023] Open
Abstract
Peripheral chemoreceptor activity/sensitivity is enhanced in chronic heart failure (HF), and sensitivity is linked to greater mortality. This study aimed to determine the role of the peripheral chemoreceptor in cardiovascular control at rest and during exercise in HF patients and controls. Clinically stable HF patients (n = 11; ejection fraction: 39 ± 5%) and risk-matched controls (n = 10; ejection fraction: 65 ± 2%) performed randomized trials with or without dopamine infusion (2 μg·min(-1)·kg(-1)) at rest and during 40% maximal voluntary contraction handgrip (HG) exercise, and a resting trial of 2 min of inspired 100% oxygen. Both dopamine and hyperoxia were used to inhibit the peripheral chemoreceptor. At rest in HF patients, dopamine decreased ventilation (P = 0.02), decreased total peripheral resistance index (P = 0.003), and increased cardiac and stroke indexes (P ≤ 0.01), yet there was no effect of dopamine on these variables in controls (P ≥ 0.7). Hyperoxia lowered ventilation in HF (P = 0.01), but not in controls (P = 0.9), indicating suppression of the peripheral chemoreceptors in HF. However, no decrease of total peripheral resistance index was observed in HF. As expected, HG increased heart rate, ventilation, and brachial conductance of the nonexercising arm in controls and HF patients. During dopamine infusion, there were no changes in mean arterial pressure, heart rate, or ventilation responses to HG in either group (P ≥ 0.26); however, brachial conductance increased with dopamine in the control group (P = 0.004), but decreased in HF (P = 0.02). Our findings indicate that the peripheral chemoreceptor contributes to cardiovascular control at rest in HF patients and during exercise in risk-matched controls.
Collapse
Affiliation(s)
- Heather Edgell
- Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada; Women and Children's Health Research Institute, University of Alberta, Edmonton, Alberta, Canada; Cardiovascular and Stroke Research Centre (ABACUS), Mazankowski Alberta Heart Institute, Edmonton, Alberta, Canada
| | - M Sean McMurtry
- Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada; Cardiovascular and Stroke Research Centre (ABACUS), Mazankowski Alberta Heart Institute, Edmonton, Alberta, Canada
| | - Mark J Haykowsky
- Cardiovascular and Stroke Research Centre (ABACUS), Mazankowski Alberta Heart Institute, Edmonton, Alberta, Canada; Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Alberta, Canada; and
| | - Ian Paterson
- Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada; Cardiovascular and Stroke Research Centre (ABACUS), Mazankowski Alberta Heart Institute, Edmonton, Alberta, Canada
| | - Justin A Ezekowitz
- Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada; Cardiovascular and Stroke Research Centre (ABACUS), Mazankowski Alberta Heart Institute, Edmonton, Alberta, Canada
| | - Jason R B Dyck
- Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada; Cardiovascular and Stroke Research Centre (ABACUS), Mazankowski Alberta Heart Institute, Edmonton, Alberta, Canada
| | - Michael K Stickland
- Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada; Cardiovascular and Stroke Research Centre (ABACUS), Mazankowski Alberta Heart Institute, Edmonton, Alberta, Canada; G.F. MacDonald Centre for Lung Health (Covenant Health), Edmonton, Alberta, Canada
| |
Collapse
|
13
|
Peng QQ, Basang Z, Cui CY, Li L, Qian J, Gesang Q, Yang L, La Z, De Y, Dawa P, Qu N, Suo Q, Dan Z, Xiao D, Wang XF, Jin L. Physiological responses and evaluation of effects of BMI, smoking and drinking in high altitude acclimatization: a cohort study in Chinese Han young males. PLoS One 2013; 8:e79346. [PMID: 24260204 PMCID: PMC3832642 DOI: 10.1371/journal.pone.0079346] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Accepted: 09/25/2013] [Indexed: 11/18/2022] Open
Abstract
High altitude acclimatization is a series of physiological responses taking places when subjects go to altitude. Many factors could influence these processes, such as altitude, ascending speed and individual characteristics. In this study, based on a repeated measurement design of three sequential measurements at baseline, acute phase and chronic phase, we evaluated the effect of BMI, smoking and drinking on a number of physiological responses in high altitude acclimatization by using mixed model and partial least square path model on a sample of 755 Han Chinese young males. We found that subjects with higher BMI responses were reluctant to hypoxia. The effect of smoking was not significant at acute phase. But at chronic phase, red blood cell volume increased less while respiratory function increased more for smoking subjects compared with nonsmokers. For drinking subjects, red blood cell volume increased less than nondrinkers at both acute and chronic phases, while blood pressures increased more than nondrinkers at acute phase and respiratory function, red blood cell volume and oxygen saturation increased more than nondrinkers at chronic phase. The heavy and long-term effect of smoking, drinking and other factors in high altitude acclimatization needed to be further studied.
Collapse
Affiliation(s)
- Qian-qian Peng
- MOE Key Laboratory of Contemporary Anthropology, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Zhuoma Basang
- High Altitude Health Science Research Center, Tibet University, Tibet Autonomous Region, China
- * E-mail: (LJ); (BZ)
| | - Chao-ying Cui
- High Altitude Health Science Research Center, Tibet University, Tibet Autonomous Region, China
| | - Lei Li
- MOE Key Laboratory of Contemporary Anthropology, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Ji Qian
- MOE Key Laboratory of Contemporary Anthropology, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai, China
- CMC Institute of Health Sciences, Taizhou, Jiangsu Province, China
| | - Quzhen Gesang
- High Altitude Health Science Research Center, Tibet University, Tibet Autonomous Region, China
| | - La Yang
- High Altitude Health Science Research Center, Tibet University, Tibet Autonomous Region, China
| | - Zong La
- High Altitude Health Science Research Center, Tibet University, Tibet Autonomous Region, China
| | - Yang De
- High Altitude Health Science Research Center, Tibet University, Tibet Autonomous Region, China
| | - Puchi Dawa
- High Altitude Health Science Research Center, Tibet University, Tibet Autonomous Region, China
| | - Ni Qu
- High Altitude Health Science Research Center, Tibet University, Tibet Autonomous Region, China
| | - Qu Suo
- High Altitude Health Science Research Center, Tibet University, Tibet Autonomous Region, China
| | - Zhen Dan
- High Altitude Health Science Research Center, Tibet University, Tibet Autonomous Region, China
| | - Duoji Xiao
- High Altitude Health Science Research Center, Tibet University, Tibet Autonomous Region, China
| | - Xiao-feng Wang
- MOE Key Laboratory of Contemporary Anthropology, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai, China
- CMC Institute of Health Sciences, Taizhou, Jiangsu Province, China
| | - Li Jin
- MOE Key Laboratory of Contemporary Anthropology, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai, China
- CMC Institute of Health Sciences, Taizhou, Jiangsu Province, China
- * E-mail: (LJ); (BZ)
| |
Collapse
|
14
|
Kayser B, Verges S. Hypoxia, energy balance and obesity: from pathophysiological mechanisms to new treatment strategies. Obes Rev 2013; 14:579-92. [PMID: 23551535 DOI: 10.1111/obr.12034] [Citation(s) in RCA: 106] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Revised: 02/22/2013] [Accepted: 03/02/2013] [Indexed: 12/17/2022]
Abstract
High altitude exposure is often accompanied by weight loss. Postulated mechanisms are a reduction of nutritional energy intake, a reduction of intestinal energy uptake from impaired intestinal function and increased energy expenditure. Beyond the field of altitude, there are good reasons for renewed interest in the relationship between hypoxia and energy balance. The increasing prevalence of obesity and associated comorbidities represent a major health concern. Obesity is frequently associated with sleep disorders leading to intermittent systemic hypoxia with deleterious cardiovascular and metabolic consequences. Hypoxic regions may be present within hypertrophic white adipose tissue leading to chronic systemic inflammation. Among the increasing number of people commuting to altitude for work or leisure, obesity is a risk factor for acute mountain sickness. Paradoxically, exposure to intermittent hypoxia might be considered as a means to lose body mass and to improve metabolic risk factors. Daytime exposure to intermittent hypoxia has been used to treat hypertension in former Soviet Union countries and is now being experimented elsewhere. Such intermittent hypoxic exposure at rest or during exercise may lead to improvement in body composition and health status with improved exercise tolerance, metabolism and systemic arterial pressure. Future research should confirm whether hypoxic training could be a new treatment strategy for weight loss and comorbidities in obese subjects and elucidate the underlying mechanisms and signalling pathways.
Collapse
Affiliation(s)
- B Kayser
- Institute of Movement Science and Sports Medicine, Faculty of medicine, University of Geneva, Geneva, Switzerland.
| | | |
Collapse
|
15
|
Babb TG. Obesity: challenges to ventilatory control during exercise--a brief review. Respir Physiol Neurobiol 2013; 189:364-70. [PMID: 23707540 DOI: 10.1016/j.resp.2013.05.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Revised: 05/14/2013] [Accepted: 05/15/2013] [Indexed: 10/26/2022]
Abstract
Obesity is a national health issue in the US. Among the many physiological changes induced by obesity, it also presents a unique challenge to ventilatory control during exercise due to increased metabolic demand of moving larger limbs, increased work of breathing due to extra weight on the chest wall, and changes in breathing mechanics. These challenges to ventilatory control in obesity can be inconspicuous or overt among obese adults but for the most part adaptation of ventilatory control during exercise in obesity appears remarkably unnoticed in the majority of obese people. In this brief review, the changes to ventilatory control required for maintaining normal ventilation during exercise will be examined, especially the interaction between respiratory neural drive and ventilation. Also, gaps in our current knowledge will be discussed.
Collapse
Affiliation(s)
- Tony G Babb
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and Department of Internal Medicine, Division of Pulmonary and Critical Care Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75231, United States.
| |
Collapse
|
16
|
Yuan H, Pinto SJ, Huang J, McDonough JM, Ward MB, Lee YN, Bradford RM, Gallagher PR, Shults J, Konstantinopoulou S, Samuel JM, Katz ES, Hua S, Tapia IE, Marcus CL. Ventilatory responses to hypercapnia during wakefulness and sleep in obese adolescents with and without obstructive sleep apnea syndrome. Sleep 2012; 35:1257-67. [PMID: 22942504 DOI: 10.5665/sleep.2082] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
STUDY OBJECTIVES Abnormal ventilatory drive may contribute to the pathophysiology of the childhood obstructive sleep apnea syndrome (OSAS). Concomitant with the obesity epidemic, more adolescents are developing OSAS. However, few studies have specifically evaluated the obese adolescent group. The authors hypothesized that obese adolescents with OSAS would have a blunted hypercapnic ventilatory response (HCVR) while awake and blunted ventilatory responses to carbon dioxide (CO(2)) during sleep compared with obese and lean adolescents without OSAS. DESIGN CVR was measured during wakefulness. During nonrapid eye movement (NREM) and rapid eye movement (REM) sleep, respiratory parameters and genioglossal electromyogram were measured during CO(2) administration in comparison with room air in obese adolescents with OSAS, obese control study participants, and lean control study participants. SETTING Sleep laboratory. PARTICIPANTS Twenty-eight obese patients with OSAS, 21 obese control study participants, and 37 lean control study participants. RESULTS The obese OSAS and obese control groups had a higher HCVR compared with the lean control group during wakefulness. During both sleep states, all 3 groups had a response to CO(2); however, the obese OSAS group had lower percentage changes in minute ventilation, inspiratory flow, inspiratory time, and tidal volume compared with the 2 control groups. There were no significance differences in genioglossal activity between groups. CONCLUSIONS HCVR during wakefulness is increased in obese adolescents. Obese adolescents with OSAS have blunted ventilatory responses to CO(2) during sleep and do not have a compensatory prolongation of inspiratory time, despite having normal CO(2) responsivity during wakefulness. Central drive may play a greater role than upper airway neuromotor tone in adapting to hypercapnia.
Collapse
Affiliation(s)
- Haibo Yuan
- Division of Respiratory Diseases, First Hospital of Jilin University, Changchun, Jilin, China
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Vearrier D, Greenberg MI. Occupational health of miners at altitude: adverse health effects, toxic exposures, pre-placement screening, acclimatization, and worker surveillance. Clin Toxicol (Phila) 2011; 49:629-40. [PMID: 21861588 DOI: 10.3109/15563650.2011.607169] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
CONTEXT Mining operations conducted at high altitudes provide health challenges for workers as well as for medical personnel. OBJECTIVE To review the literature regarding adverse health effects and toxic exposures that may be associated with mining operations conducted at altitude and to discuss pre-placement screening, acclimatization issues, and on-site surveillance strategies. METHODS We used the Ovid ( http://ovidsp.tx.ovid.com ) search engine to conduct a MEDLINE search for "coal mining" or "mining" and "altitude sickness" or "altitude" and a second MEDLINE search for "occupational diseases" and "altitude sickness" or "altitude." The search identified 97 articles of which 76 were relevant. In addition, the references of these 76 articles were manually reviewed for relevant articles. CARDIOVASCULAR EFFECTS: High altitude is associated with increased sympathetic tone that may result in elevated blood pressure, particularly in workers with pre-existing hypertension. Workers with a history of coronary artery disease experience ischemia at lower work rates at high altitude, while those with a history of congestive heart failure have decreased exercise tolerance at high altitude as compared to healthy controls and are at higher risk of suffering an exacerbation of their heart failure. PULMONARY EFFECTS: High altitude is associated with various adverse pulmonary effects, including high-altitude pulmonary edema, pulmonary hypertension, subacute mountain sickness, and chronic mountain sickness. Mining at altitude has been reported to accelerate silicosis and other pneumoconioses. Miners with pre-existing pneumoconioses may experience an exacerbation of their condition at altitude. Persons traveling to high altitude have a higher incidence of Cheyne-Stokes respiration while sleeping than do persons native to high altitude. Obesity increases the risk of pulmonary hypertension, acute mountain sickness, and sleep-disordered breathing. NEUROLOGICAL EFFECTS: The most common adverse neurological effect of high altitude is acute mountain sickness, while the most severe adverse neurological effect is high-altitude cerebral edema. Poor sleep quality and sleep-disordered breathing may contribute to daytime sleepiness and impaired cognitive performance that could potentially result in workplace injuries, particularly in miners who are already at increased risk of suffering unintentional workplace injuries. OPHTHALMOLOGICAL EFFECTS: Adverse ophthalmological effects include increased exposure to ultraviolet light and xerophthalmia, which may be further exacerbated by occupational dust exposure. RENAL EFFECTS: High altitude is associated with a protective effect in patients with renal disease, although it is unknown how this would affect miners with a history of chronic renal disease from exposure to silica and other renal toxicants. HEMATOLOGICAL EFFECTS: Advanced age increases the risk of erythrocytosis and chronic mountain sickness in miners. Thrombotic and thromboembolic events are also more common at high altitude. MUSCULOSKELETAL EFFECTS: Miners are at increased risk for low back pain due to occupational factors, and the easy fatigue at altitude has been reported to further predispose workers to this disorder. TOXIC EXPOSURES: Diesel emissions at altitude contain more carbon monoxide due to increased incomplete combustion of fuel. In addition, a given partial pressure of carbon monoxide at altitude will result in a larger percentage of carboxyhemoglobin at altitude. Miners with a diagnosis of chronic obstructive pulmonary disease may be at higher risk for morbidity from exposure to diesel exhaust at altitude. CONCLUSIONS Both mining and work at altitude have independently been associated with a number of adverse health effects, although the combined effect of mining activities and high altitude has not been adequately studied. Careful selection of workers, appropriate acclimatization, and limited on-site surveillance can help control most health risks. Further research is necessary to more completely understand the risks of mining at altitude and delineate what characteristics of potential employees put them at risk for altitude-related morbidity or mortality.
Collapse
Affiliation(s)
- David Vearrier
- Department of Emergency Medicine, Drexel University College of Medicine, Philadelphia, PA 19102, USA
| | | |
Collapse
|
18
|
Heinicke K, Taivassalo T, Wyrick P, Wood H, Babb TG, Haller RG. Exertional dyspnea in mitochondrial myopathy: clinical features and physiological mechanisms. Am J Physiol Regul Integr Comp Physiol 2011; 301:R873-84. [PMID: 21813873 DOI: 10.1152/ajpregu.00001.2011] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Exertional dyspnea limits exercise in some mitochondrial myopathy (MM) patients, but the clinical features of this syndrome are poorly defined, and its underlying mechanism is unknown. We evaluated ventilation and arterial blood gases during cycle exercise and recovery in five MM patients with exertional dyspnea and genetically defined mitochondrial defects, and in four control subjects (C). Patient ventilation was normal at rest. During exercise, MM patients had low Vo(2peak) (28 ± 9% of predicted) and exaggerated systemic O(2) delivery relative to O(2) utilization (i.e., a hyperkinetic circulation). High perceived breathing effort in patients was associated with exaggerated ventilation relative to metabolic rate with high VE/VO(2peak), (MM = 104 ± 18; C = 42 ± 8, P ≤ 0.001), and Ve/VCO(2peak)(,) (MM = 54 ± 9; C = 34 ± 7, P ≤ 0.01); a steeper slope of increase in ΔVE/ΔVCO(2) (MM = 50.0 ± 6.9; C = 32.2 ± 6.6, P ≤ 0.01); and elevated peak respiratory exchange ratio (RER), (MM = 1.95 ± 0.31, C = 1.25 ± 0.03, P ≤ 0.01). Arterial lactate was higher in MM patients, and evidence for ventilatory compensation to metabolic acidosis included lower Pa(CO(2)) and standard bicarbonate. However, during 5 min of recovery, despite a further fall in arterial pH and lactate elevation, ventilation in MM rapidly normalized. These data indicate that exertional dyspnea in MM is attributable to mitochondrial defects that severely impair muscle oxidative phosphorylation and result in a hyperkinetic circulation in exercise. Exaggerated exercise ventilation is indicated by markedly elevated VE/VO(2), VE/VCO(2), and RER. While lactic acidosis likely contributes to exercise hyperventilation, the fact that ventilation normalizes during recovery from exercise despite increasing metabolic acidosis strongly indicates that additional, exercise-specific mechanisms are responsible for this distinctive pattern of exercise ventilation.
Collapse
Affiliation(s)
- Katja Heinicke
- Neuromuscular Center, Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, 7232 Greenville Ave., #435, Dallas, TX 75231-5129, USA.
| | | | | | | | | | | |
Collapse
|
19
|
Mieske K, Flaherty G, O'Brien T. Journeys to high altitude--risks and recommendations for travelers with preexisting medical conditions. J Travel Med 2010; 17:48-62. [PMID: 20074100 DOI: 10.1111/j.1708-8305.2009.00369.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Kelly Mieske
- Department of Medicine, National University of Ireland, Galway, Ireland.
| | | | | |
Collapse
|
20
|
Interval hypoxic training improves autonomic cardiovascular and respiratory control in patients with mild chronic obstructive pulmonary disease. J Hypertens 2009; 27:1648-54. [PMID: 19387363 DOI: 10.1097/hjh.0b013e32832c0018] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES Chronic obstructive pulmonary disease (COPD) is associated with cardiac autonomic nervous system dysregulation. This study evaluates the effects of interval hypoxic training on cardiovascular and respiratory control in patients with mild COPD. METHODS In 18 eucapnic normoxic mild COPD patients (age 51.7 +/- 2.4 years, mean +/- SEM), randomly assigned to either training or placebo group, and 14 age-matched healthy controls (47.7 +/- 2.8 years), we monitored end-tidal carbon dioxide, airway flow, arterial oxygen saturation, electrocardiogram, and continuous noninvasive blood pressure at rest, during progressive hypercapnic hyperoxia and isocapnic hypoxia to compare baroreflex sensitivity to hypoxia and hypercapnia before and after 3 weeks of hypoxic training. In double-blind fashion, both groups received 15 sessions of passive intermittent hypoxia (training group) or normoxia (placebo group). For the hypoxia group, each session consisted of three to five hypoxic (15-12% oxygen) periods (3-5 min) with 3-min normoxic intervals. The placebo group inhaled normoxic air. RESULTS Before training, COPD patients showed depressed baroreflex sensitivity, as compared with healthy individuals, without evident chemoreflex abnormalities. After training, in contrast to placebo group, the training group showed increased (P < 0.05) baroreflex sensitivity up to normal levels and selectively increased hypercapnic ventilatory response (P < 0.05), without changes in hypoxic ventilatory response. CONCLUSION Eucapnic normoxic mild COPD patients already showed signs of cardiovascular autonomic abnormalities at baseline, which normalized with hypoxic training. If confirmed in more severe patients, interval hypoxic training may be a therapeutic strategy to rebalance early autonomic dysfunction in COPD patients.
Collapse
|
21
|
Abstract
The literature on pulmonary gas exchange at rest, during exercise, and with weight loss in the morbidly obese (body mass index or BMI > or = 40 kg m(-2)) is reviewed. Forty-one studies were found (768 subjects weighted mean = 40 years old, BMI = 48 kg m(-2)). The alveolar-to-arterial oxygen partial pressure difference (AaDO2) was large at rest in upright subjects at sea level (23, range 5-38 mmHg) while the arterial pressure of oxygen (PaO2) was low (81, range 50-95 mmHg). Arterial pressure of carbon dioxide (PaCO2) was normal. At peak exercise (162 W), gas exchange improves. Weight loss of 45 kg (BMI = -13 kg m(-2)) over 18 months is associated with an improvement in PaO2 (by 10 mmHg, range 1-23 mmHg), a reduction in AaDO2 (by 8 mmHg, range -3 to -16 mmHg), and PaCO2 (by -3 mmHg, range 3 to -14 mmHg) at rest. Every 5-6 kg reduction in weight increases PaO2 by 1 and reduces AaDO2 by 1 mmHg, respectively. Morbidly obese women have better gas exchange at rest compared with morbidly obese men which is likely due to lower waist-to-hip ratios in women than from differences in weight or BMI.
Collapse
Affiliation(s)
- G S Zavorsky
- Department of Obstetrics, Gynecology and Women's Health, School of Medicine, Saint Louis University, Saint Mary's Health Center, Saint Louis, Missouri 63117, USA.
| | | |
Collapse
|
22
|
Wu TY, Ding SQ, Liu JL, Yu MT, Jia JH, Chai ZC, Dai RC, Zhang SL, Li BY, Pan L, Liang BZ, Zhao JZ, Qi DT, Sun YF, Kayser B. Who should not go high: chronic disease and work at altitude during construction of the Qinghai-Tibet railroad. High Alt Med Biol 2007; 8:88-107. [PMID: 17584003 DOI: 10.1089/ham.2007.1015] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
From 2001 to 2005, a new railroad linking Beijing with Lhasa was built by more than 100,000 workers, of whom 80% traveled from their lowland habitat to altitudes up to 5000 m to work on the railroad. We report on the medical conditions of 14,050 of these altitude workers, specifically with regard to preexisting illness. All subjects were seen at low and high altitude. Average age was 29.5 +/- 7.4 (SD) yr, range 20 to 62 yr; 98.8% of the subjects were men and 1.2% were women. Overall incidence of AMS upon first-time exposure was 51%, that of HACE 0.28%, and that of HAPE 0.49%. About 1% of the subjects were hypertensive before altitude exposure. Those with blood pressure >or=160/95 were excluded from employment at altitude. Altitude exposure led to a greater increase of blood pressure in hypertensives compared to normotensives. On prealtitude screening prevalence of cardiac arrhythmias was 0.33%. Since the majority of these were rather benign and occurring in young and otherwise healthy subjects, we allowed altitude employment. Follow-up at altitude was uneventful. Subjects with coronary heart disease and diabetes were excluded from altitude employment. Obesity was a risk factor for acute mountain sickness and for reduced work performance at altitude. Overweight subjects lost more weight during their altitude stay than subjects with normal weight. Altitude exposure was a risk factor for upper gastrointestinal tract bleeding, especially in combination with alcohol, aspirin, and dexamethasone intake. Asthmatic subjects generally did better at altitude compared to low altitude, with the exception of one subject who experienced an asthma episode from pollen exposure. In conclusion, careful evaluation of preexisting chronic illness and risk factors allowed prevention of altitude deterioration of a preexisting health condition, all the while allowing subjects with some specific conditions to work and live at altitude without problems.
Collapse
Affiliation(s)
- Tian-Yi Wu
- Physiological Research Group of the Ministry of Railroad, P. R. China.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Severinghaus JW. Sightings. High Alt Med Biol 2005. [DOI: 10.1089/ham.2005.6.198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
|