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      Cardiovascular System Response to Carbon Dioxide and Exercise in Oxygen-Enriched Environment at 3800 m

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          Abstract

          Background: This study explores the responses of the cardiovascular system as humans exercise in an oxygen-enriched room at high altitude under various concentrations of CO 2. Methods: The study utilized a hypobaric chamber set to the following specifications: 3800 m altitude with 25% O 2 and different CO 2 concentrations of 0.5% (C1), 3.0% (C2) and 5.0% (C3). Subjects exercised for 3 min three times, separated by 30 min resting periods in the above-mentioned conditions, at sea level (SL) and at 3800 m altitude (HA). The changes of heart rate variability, heart rate and blood pressure were analyzed. Results: Total power (TP) and high frequency power (HF) decreased notably during post-exercise at HA. HF increased prominently earlier the post-exercise period at 3800 m altitude with 25% O 2 and 5.0% CO 2 (C3), while low frequency power (LF) changed barely in all tests. The ratios of LF/HF were significantly higher during post-exercise in HA, and lower after high intensity exercise in C3. Heart rate and systolic blood pressure increased significantly in HA and C3. Conclusions: Parasympathetic activity dominated in cardiac autonomic modulation, and heart rate and blood pressure increased significantly after high intensity exercise in C3.

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          The heart and pulmonary circulation at high altitudes: healthy highlanders and chronic mountain sickness.

          Dante Peñaloza, Javier Arias-Stella (2007)
          More than 140 million people worldwide live >2500 m above sea level. Of them, 80 million live in Asia, and 35 million live in the Andean mountains. This latter region has its major population density living above 3500 m. The primary objective of the present study is to review the physiology, pathology, pathogenesis, and clinical features of the heart and pulmonary circulation in healthy highlanders and patients with chronic mountain sickness. A systematic review of worldwide literature was undertaken, beginning with the pioneering work done in the Andes several decades ago. Original articles were analyzed in most cases and English abstracts or translations of articles written in Chinese were reviewed. Pulmonary hypertension in healthy highlanders is related to a delayed postnatal remodeling of the distal pulmonary arterial branches. The magnitude of pulmonary hypertension increases with the altitude level and the degree of exercise. There is reversal of pulmonary hypertension after prolonged residence at sea level. Chronic mountain sickness develops when the capacity for altitude adaptation is lost. These patients have moderate to severe pulmonary hypertension with accentuated hypoxemia and exaggerated polycythemia. The clinical picture of chronic mountain sickness differs from subacute mountain sickness and resembles other chronic altitude diseases described in China and Kyrgyzstan. The heart and pulmonary circulation in healthy highlanders have distinct features in comparison with residents at sea level. Chronic mountain sickness is a public health problem in the Andean mountains and other mountainous regions around the world. Therefore, dissemination of preventive and therapeutic measures is essential.
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            Physiological adaptation of the cardiovascular system to high altitude.

            Robert Naeije (2010)
            Altitude exposure is associated with major changes in cardiovascular function. The initial cardiovascular response to altitude is characterized by an increase in cardiac output with tachycardia, no change in stroke volume, whereas blood pressure may temporarily be slightly increased. After a few days of acclimatization, cardiac output returns to normal, but heart rate remains increased, so that stroke volume is decreased. Pulmonary artery pressure increases without change in pulmonary artery wedge pressure. This pattern is essentially unchanged with prolonged or lifelong altitude sojourns. Ventricular function is maintained, with initially increased, then preserved or slightly depressed indices of systolic function, and an altered diastolic filling pattern. Filling pressures of the heart remain unchanged. Exercise in acute as well as in chronic high-altitude exposure is associated with a brisk increase in pulmonary artery pressure. The relationships between workload, cardiac output, and oxygen uptake are preserved in all circumstances, but there is a decrease in maximal oxygen consumption, which is accompanied by a decrease in maximal cardiac output. The decrease in maximal cardiac output is minimal in acute hypoxia but becomes more pronounced with acclimatization. This is not explained by hypovolemia, acid-bases status, increased viscosity on polycythemia, autonomic nervous system changes, or depressed systolic function. Maximal oxygen uptake at high altitudes has been modeled to be determined by the matching of convective and diffusional oxygen transport systems at a lower maximal cardiac output. However, there has been recent suggestion that 10% to 25% of the loss in aerobic exercise capacity at high altitudes can be restored by specific pulmonary vasodilating interventions. Whether this is explained by an improved maximum flow output by an unloaded right ventricle remains to be confirmed. Altitude exposure carries no identified risk of myocardial ischemia in healthy subjects but has to be considered as a potential stress in patients with previous cardiovascular conditions.
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              Association of ventilation rates and CO2 concentrations with health and other responses in commercial and institutional buildings.

              O. A. Seppanen, W J Fisk, M J Mendell (1999)
              This paper reviews current literature on the associations of ventilation rates and carbon dioxide concentrations in non-residential and non-industrial buildings (primarily offices) with health and other human outcomes. Twenty studies, with close to 30,000 subjects, investigated the association of ventilation rates with human responses, and 21 studies, with over 30,000 subjects, investigated the association of carbon dioxide concentration with these responses. Almost all studies found that ventilation rates below 10 Ls-1 per person in all building types were associated with statistically significant worsening in one or more health or perceived air quality outcomes. Some studies determined that increases in ventilation rates above 10 Ls-1 per person, up to approximately 20 Ls-1 per person, were associated with further significant decreases in the prevalence of sick building syndrome (SBS) symptoms or with further significant improvements in perceived air quality. The carbon dioxide studies support these findings. About half of the carbon dioxide studies suggest that the risk of sick building syndrome symptoms continued to decrease significantly with decreasing carbon dioxide concentrations below 800 ppm. The ventilation studies reported relative risks of 1.5-2 for respiratory illnesses and 1.1-6 for sick building syndrome symptoms for low compared to high low ventilation rates.
              Article 0 comments Cited 130 times – based on 0 reviews     Review now
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                Author and article information

                Contributors
                Paul B. Tchounwou: Role: Academic Editor
                Journal
                Journal ID (nlm-ta): Int J Environ Res Public Health
                Journal ID (iso-abbrev): Int J Environ Res Public Health
                Journal ID (publisher-id): ijerph
                Title: International Journal of Environmental Research and Public Health
                Publisher: MDPI
                ISSN (Print): 1661-7827
                ISSN (Electronic): 1660-4601
                Publication date (Electronic): 18 September 2015
                Publication date (Print): September 2015
                Volume: 12
                Issue: 9
                Pages: 11781-11796
                Affiliations
                [1 ]School of Aeronautic Science and Engineering, Beihang University, Beijing 100191, China; E-Mail: guohui_l@ 123456buaa.edu.cn
                [2 ]High Altitude Physiology Laboratory, Institute of Aviation Medicine, Air Force, Beijing 100142, China; E-Mails: liu_xiao_peng@ 123456hotmail.com (X.L.); zhifeng_q@ 123456hotmail.com (Z.Q.); guzhao_gz@ 123456hotmail.com (Z.G.); guiyouw@ 123456hotmail.com (G.W.); swr7823@ 123456sohu.com (W.S.); wendongqing@ 123456gmail.com (D.W.); lihua19780420@ 123456163.com (L.Y.)
                Author notes
                [* ]Authors to whom correspondence should be addressed; E-Mails: yongchang_l@ 123456hotmail.com (Y.L.); xiao-hj@ 123456263.net (H.X.); Tel.: +86-010-6692-7146 (Y.L.); +86-010-6692-7148 (H.X.); Fax: +86-010-6692-7092 (Y.L.).
                Article
                Publisher ID: ijerph-12-11781
                DOI: 10.3390/ijerph120911781
                PMC ID: 4586707
                PubMed ID: 26393634
                SO-VID: 946c8534-276e-4cf1-a13b-624a2f4ace28
                Copyright © © 2015 by the authors; licensee MDPI, Basel, Switzerland.
                License:

                This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution license ( http://creativecommons.org/licenses/by/4.0/).

                History
                Date received : 27 May 2015
                Date accepted : 06 August 2015
                Categories
                Subject: Article

                ScienceOpen disciplines: Public health
                Keywords: heart rate variability,heart rate,blood pressure,cardiac autonomic modulation,exercise
                Data availability:
                ScienceOpen disciplines: Public health
                Keywords: heart rate variability, heart rate, blood pressure, cardiac autonomic modulation, exercise

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