Pediatric asthma and altitude: a complex interplay between different environmental factors.

Asthma is one of the most common non-communicable diseases, and its prevalence and morbidity are influenced by a wide array of factors that are only partially understood. In addition to individual predisposition linked to genetic background and early life infections, environmental factors are crucial in determining the impact of asthma both on an individual patient and on a population level.Several studies have examined the role of the environment where asthmatic subjects live in the pathogenesis of asthma. This review aims to investigate the differences in the prevalence and characteristics of asthma between the pediatric population residing at higher altitudes and children living at lower altitudes, trying to define factors that potentially determine such differences. For this purpose, we reviewed articles from the literature concerning observational studies assessing the prevalence of pediatric asthma in these populations and its characteristics, such as spirometric and laboratory parameters and associated sensitization to aeroallergens.Despite the heterogeneity of the environments examined, the hypothesis of a beneficial effect of residing at a higher altitude on the prevalence of pediatric asthma could be confirmed, as well as a good profile on airway inflammation in asthmatic children. However, the possibility of a higher hospitalization risk for asthma in children living at higher altitudes was demonstrated. Moreover, a positive association between residing at a higher altitude and sensitization to pollens and between lower altitude and sensitization to house dust mites could be confirmed in some pediatric patients, even if the results are not homogeneous, probably due to the different geographical and climatic regions considered. Nonetheless, further studies, e.g., extensive and international works, need to be conducted to better understand the complex interplay between different environmental factors, such as altitude, and the pathogenesis of asthma and how its prevalence and characteristics could vary due to climate change.

Inspiratory-Expiratory Muscle Training Improved Respiratory Muscle Strength in Dialysis Patients: A Pilot Randomised Trial.

End-stage kidney disease (ESKD) exposes patients to progressive physical deconditioning involving the respiratory muscles. The aim of this pilot randomized controlled trial was to determine the feasibility and effectiveness of low-intensity respiratory muscle training (RMT) learned at the hospital and performed at home. A group of ESKD patients (n = 22) were randomized into RMT or usual care (control group, CON) in a 1:1 ratio. The respiratory training was performed at home with an inspiratory-expiratory system for a total of 5 min of breathing exercises in a precise rhythm (8 breaths per minute) interspersed with 1 min of rest, two times per day on nondialysis days for a total of 4 weeks, with the air resistance progressively increasing. Outcome measures were carried out every 4 weeks for 3 consecutive months, with the training executed from the 5th to the 8th week. Primary outcomes were maximal inspiratory and expiratory pressure (MIP, MEP), while secondary outcomes were lung capacity (FEV1, FVC, MVV). Nineteen patients without baseline between-group differences completed the trial (T: n = 10; Age: 63 ± 10; Males: n = 12). Both MIP and MEP significantly improved at the end of training in the T group only, with a significant difference of MEP of 23 cmH2O in favor of the RMT group (p = 0.008). No significant variations were obtained for FVC, FEV1 or MVV in either group, but there was a greater decreasing trend over time for the CON group, particularly for FVC (t = -2.00; p = 0.046). Low-fatiguing home-based RMT, with a simple device involving both inspiratory and expiratory muscles, may significantly increase respiratory muscle strength.

A positive effect of a short period stay in Alpine environment on lung function in asthmatic children.

Lung function is a central issue in diagnosis and determination of asthma severity and asthma control has been previously reported to improve after a stay in mountain environment for at least 2 weeks. No data are available for shorter periods of stay, in particular for small airways during a stay at altitude. The aim of this study is to focus on changes in respiratory function, regarding both the central airways and the peripheral airways in the first 2 weeks of stay in a mountain environment in asthmatic children. In this study, 66 asthmatic children (age: 14 ± 2.8 years) were evaluated through spirometric and oscillometric tests at the time of arrival at the Istituto Pio XII, Misurina (BL), Italy, 1756 m above sea level (T0), after 24 h (T1), and 168 h (T2) of stay. FEV1%, FEF25%-75%, and FEV1/FVC increased significantly from T0 value both at T1 and T2 (respectively, p = 0.0002, p < 0.0001, p = 0.0002). Oscillometry showed a significant improvement in R5, R20, and R5-20 at both T1 and T2 as compared to T0 (respectively, p = 0.0001, p = 0.0002, and p = 0.049). Reactance at 5 Hz (X5) improved significantly at T2 versus T0, p = 0.0022. The area under reactance curve between Fres and 5 Hz (AX) was significantly reduced (p = 0.0001) both at T1 and T2 as compared to T0. This study shows an improvement in respiratory indices as soon as after 24 h of stay at altitude, persisting in the following week.

Effects of acetazolamide on pulmonary artery pressure and prevention of high-altitude pulmonary edema after rapid active ascent to 4,559 m.

Acetazolamide prevents acute mountain sickness (AMS) by inhibition of carbonic anhydrase. Since it also reduces acute hypoxic pulmonary vasoconstriction (HPV), it may also prevent high-altitude pulmonary edema (HAPE) by lowering pulmonary artery pressure. We tested this hypothesis in a randomized, placebo-controlled, double-blind study. Thirteen healthy, nonacclimatized lowlanders with a history of HAPE ascended (<22 h) from 1,130 to 4,559 m with one overnight stay at 3,611 m. Medications were started 48 h before ascent (acetazolamide: n = 7, 250 mg 3 times/day; placebo: n = 6, 3 times/day). HAPE was diagnosed by chest radiography and pulmonary artery pressure by measurement of right ventricular to atrial pressure gradient (RVPG) by transthoracic echocardiography. AMS was evaluated with the Lake Louise Score (LLS) and AMS-C score. The incidence of HAPE was 43% versus 67% (acetazolamide vs. placebo, P = 0.39). Ascent to altitude increased RVPG from 20 ± 5 to 43 ± 10 mmHg (P < 0.001) without a group difference (P = 0.68). Arterial Po2 fell to 36 ± 9 mmHg (P < 0.001) and was 8.5 mmHg higher with acetazolamide at high altitude (P = 0.025). At high altitude, the LLS and AMS-C score remained lower in those taking acetazolamide (both P < 0.05). Although acetazolamide reduced HAPE incidence by 35%, this effect was not statistically significant, and was considerably less than reductions of about 70%-100% with prophylactic dexamethasone, tadalafil, and nifedipine performed with the same ascent profile at the same location. We could not demonstrate a reduction in RVPG compared with placebo treatment despite reductions in AMS severity and better arterial oxygenation. Limited by small sample size, our data do not support recommending acetazolamide for the prevention of HAPE in mountaineers ascending rapidly to over 4,500 m.NEW & NOTEWORTHY This randomized, placebo-controlled, double-blind study is the first to investigate whether acetazolamide, which reduces acute mountain sickness (AMS), inhibits short-term hypoxic pulmonary vasoconstriction, and also prevents high-altitude pulmonary edema (HAPE) in a fast-climbing ascent to 4,559 m. We found no statistically significant reduction in HAPE incidence or differences in hypoxic pulmonary artery pressures compared with placebo despite reductions in AMS and greater ventilation-induced arterial oxygenation. Our data do not support recommending acetazolamide for HAPE prevention.

Alpine altitude climate treatment for severe and uncontrolled asthma: An EAACI position paper.

Currently available European Alpine Altitude Climate Treatment (AACT) programs combine the physical characteristics of altitude with the avoidance of environmental triggers in the alpine climate and a personalized multidisciplinary pulmonary rehabilitation approach. The reduced barometric pressure, oxygen pressure, and air density, the relatively low temperature and humidity, and the increased UV radiation at moderate altitude induce several physiological and immunological adaptation responses. The environmental characteristics of the alpine climate include reduced aeroallergens such as house dust mites (HDM), pollen, fungi, and less air pollution. These combined factors seem to have immunomodulatory effects controlling pathogenic inflammatory responses and favoring less neuro-immune stress in patients with different asthma phenotypes. The extensive multidisciplinary treatment program may further contribute to the observed clinical improvement by AACT in asthma control and quality of life, fewer exacerbations and hospitalizations, reduced need for oral corticosteroids (OCS), improved lung function, decreased airway hyperresponsiveness (AHR), improved exercise tolerance, and improved sinonasal outcomes. Based on observational studies and expert opinion, AACT represents a valuable therapy for those patients irrespective of their asthma phenotype, who cannot achieve optimal control of their complex condition despite all the advances in medical science and treatment according to guidelines, and therefore run the risk of falling into a downward spiral of loss of physical and mental health. In the light of the observed rapid decrease in inflammation and immunomodulatory effects, AACT can be considered as a natural treatment that targets biological pathways.

Supervised exercise training improves endothelial function in COPD patients: a method to reduce cardiovascular risk?

Supervised exercise training is key to health improvement in chronic obstructive pulmonary disease patients https://bit.ly/2AdfKvb.

Respiratory Effects of Exposure to Traffic-Related Air Pollutants During Exercise.

Traffic-related air pollution (TRAP) is increasing worldwide. Habitual physical activity is known to prevent cardiorespiratory diseases and mortality, but whether exposure to TRAP during exercise affects respiratory health is still uncertain. Exercise causes inflammatory changes in the airways, and its interaction with the effects of TRAP or ozone might be detrimental, for both athletes exercising outdoor and urban active commuters. In this Mini-Review, we summarize the literature on the effects of exposure to TRAP and/or ozone during exercise on lung function, respiratory symptoms, performance, and biomarkers. Ozone negatively affected pulmonary function after exercise, especially after combined exposure to ozone and diesel exhaust (DE). Spirometric changes after exercise during exposure to particulate matter and ultrafine particles suggest a decrease in lung function, especially in patients with chronic obstructive pulmonary disease. Ozone frequently caused respiratory symptoms during exercise. Women showed decreased exercise performance and higher symptom prevalence than men during TRAP exposure. However, performance was analyzed in few studies. To date, research has not identified reliable biomarkers of TRAP-related lung damage useful for monitoring athletes' health, except in scarce studies on airway cells obtained by induced sputum or bronchoalveolar lavage. In conclusion, despite partly counteracted by the positive effects of habitual exercise, the negative effects of TRAP exposure to pollutants during exercise are hard to assess: outdoor exercise is a complex model, for multiple and variable exposures to air pollutants and pollutant concentrations. Further studies are needed to identify pollutant and/or time thresholds for performing safe outdoor exercise in cities.

Indoor air pollution exposure effects on lung and cardiovascular health in the High Himalayas, Nepal: An observational study.

BACKGROUND: Exposure to indoor biomass fuel smoke is associated with increased morbidity and mortality. The aim of this study is to evaluate the association between exposure to indoor biomass burning and early pulmonary and cardiovascular damage. METHODS: The indoor levels of particulate matter (PM) [PM10, PM2.5] and black carbon (BC) were monitored in 32 houses in a Himalayan village. Seventy-eight subjects were submitted to spirometry and cardiovascular evaluation [carotid to femoral pulse wave velocity (PWV) and echocardiography]. RESULTS: Peak indoor BC concentration up to 100 µg m-3 and PM10 - PM2.5 up to 1945-592 µg m-3 were measured. We found a non-reversible bronchial obstruction in 18% of subjects ≥40 yr; mean forced expiratory flow between 25% and 75% of the forced vital capacity (FEF25-75) <80% in 54% of subjects, suggestive of early respiratory impairment, significantly and inversely related to age. Average BC was correlated with right ventricular-right atrium gradient (R = 0.449,p = .002), total peripheral resistances (TPR) (R = 0.313,p = .029) and PWV (R = 0.589,p < .0001) especially in subjects >30 yr. In multiple variable analysis, BC remained an independent predictor of PWV (ß = 0.556,p = .001), and TPR (ß = 0.366;p = .018). CONCLUSIONS: Indoor pollution exposure is associated to early pulmonary and cardiovascular damages, more evident for longer duration and higher intensity exposure.

Endothelial Function in COPD Is in an Intermediate Position Between Healthy Subjects and Coronary Artery Disease Patients and Is Related to Physical Activity.

Patients with chronic obstructive pulmonary disease (COPD) have an increased risk of ischemic heart disease. Endothelial dysfunction may play a role in the onset of cardiovascular event. Previous studies showed an impaired endothelial function (measured by flow-mediated dilation, FMD) in COPD patients compared to healthy subjects. To the best of our knowledge no study has compared FMD in COPD and in cardiac (coronary artery disease, CAD) patients. We aimed to assess FMD in healthy subjects, COPD, CAD, and COPD + CAD. The main result is that FMD in COPD is reduced and is in an intermediate position between healthy subjects and CAD or COPD + CAD; this impairment can contribute to explain the higher prevalence of cardiovascular disease in COPD. The only determinant independently associated with FMD in all subjects is the physical activity level, irrespective of the traditional risk factors (i.e., smoke, dyslipidemia, hypertension).

Home-Based, Moderate-Intensity Exercise Training Using a Metronome Improves the Breathing Pattern and Oxygen Saturation During Exercise in Patients With COPD.

PURPOSE: One of the well-known but less-investigated effects of pulmonary rehabilitation in patients with chronic obstructive pulmonary disease (COPD) is the change in breathing pattern toward a more efficient one (higher tidal volume [VT], lower breathing frequency). Evidence suggests this change can be obtained only with supervised, high-intensity exercise training (ExTr). However, some patients either do not have such programs available or are unable to exercise at higher intensity. We evaluated the effects of a 12-wk, moderate-intensity, home-monitored ExTr program using a metronome on the breathing pattern, oxygen saturation (SpO2), and dyspnea during exercise in patients with COPD. METHODS: Twenty-one patients with COPD (7 female, aged 64-85 yr) performed spirometry, incremental, and endurance walking tests (at 60% of maximal walking speed) on a treadmill before and after training. During the endurance test, patients were equipped with an instrument that continuously monitored ventilation ((Equation is included in full-text article.)E), breathing pattern, and SpO2. Patients trained at home for 12 wk, 30 min/d for at least 4 d/wk at moderate intensity. A metronome paced the walking speed. RESULTS: Sixteen patients completed the program. After training, a significant change was observed in breathing pattern (lower (Equation is included in full-text article.)E and (Equation is included in full-text article.)E/VT ratio; P < .001), a higher SpO2 (P < .001), and a lower dyspnea perception at the same work intensity (P < .01). The (Equation is included in full-text article.)E/VT ratio and SpO2 during exercise were significantly related (r = 0.56, P = .001). CONCLUSION: A change in breathing pattern towards more efficient ventilation can be obtained with a moderate, home-monitored ExTr program with a pace that is controlled by a metronome. Decreased (Equation is included in full-text article.)E/VT was associated with an improved SpO2 during exercise.

Relationship Between Occupational Physical Activity and Subclinical Vascular Damage in Moderate-Altitude Dwellers.

Ujka, Kristian, Rosa Maria Bruno, Luca Bastiani, Eva Bernardi, Paolo Sdringola, Nenad Dikic, Bikash Basyal, Sanjeeb Sundarshan Bhandari, Buddha Basnyat, Annalisa Cogo, and Lorenza Pratali. Relationship between occupational physical activity and subclinical vascular damage in moderate-altitude dwellers. High Alt Med Biol. 18:249-257, 2017. BACKGROUND: Occupational physical activity (OPA) has been associated with increased cardiovascular (CV) events. The aim of this study was to investigate the association between OPA and markers of subclinical vascular damage among a moderate-altitude population living in the rural village of Chaurikharka (Nepal; 2600 m sea level). METHODS: Seventy-two individuals (age 42 ± 15 years, ranges 15-85 years, 23 men) were enrolled. Physical activity (PA) was evaluated using the International Physical Activity Questionnaire (IPAQ). Carotid-femoral pulse wave velocity (PWV), carotid ultrasound assessment, and flow-mediated dilation (FMD) were performed. RESULTS: OPA was 9860 ± 5385 Metabolic Equivalent of Task (MET)-minutes/week, representing 77% of total energy expenditure, with 97% of the population performing high-intensity PA. In the univariate analysis, OPA was significantly associated with PWV (ß = 0.474, p = 0.001) and carotid stiffness (CS) (ß = 0.29, p = 0.019). In the multivariate analysis, including age, sex, oxygen saturation, mean blood pressure, low-density lipoprotein (LDL), and OPA, OPA remained an independent predictor of PWV (ß = 0.403, p = 0.001) but not of CS (ß = 0.028, p = 0.8). OPA remained an independent predictor of PWV independently from the Framingham risk score (FRS). CONCLUSION: High-intensity OPA shows a positive, independent association with aortic stiffness in Himalayan moderate-altitude dwellers. This study suggests how vigorous OPA performed in moderate altitude may be a CV risk factor.

Residence at Moderate Versus Low Altitude Is Effective at Maintaining Higher Oxygen Saturation During Exercise and Reducing Acute Mountain Sickness Following Fast Ascent to 4559 m.

OBJECTIVE: To continuously monitor oxygen saturation (SpO2) by pulse oximeter and assess the development of acute mountain sickness (AMS) using the Lake Louise Score (LLS) during ascent from 1154 to 4559 m in 2 groups of subjects: 10 moderate-altitude residents (MAR; ≥1000-≤2500 m) and 34 low-altitude residents (LAR). MAR are reported to have a lower incidence of AMS during ascent to higher altitudes compared with LAR. Whether this is related to higher SpO2 is still open to debate. METHODS: Seventy subjects were recruited; 24-hour SpO2 monitoring with finger pulse oximetry was performed. All subjects rode a cable car from 1154 to 3275 m and then climbed to 3647 m, where 60 subjects (LAR) overnighted. The second day, 34/60 LAR reached the highest altitude. Ten subjects who lived permanently at 1100 to 1400 m (MAR) climbed directly to 4559 m without an overnight stop. RESULTS: One LAR was excluded from the analysis because he performed a preacclimatization. We compared data of 10 MAR with data of 33 LAR who reached 4559 m. Two MAR had an LLS of 3, and 8 scored <3. Six LAR had an LLS of 3 to 4, 8 scored ≥5, and 19 scored <3. SpO2 monitoring showed higher mean SpO2 in MAR during ascent above 3600 m compared with LAR (MAR, 79±4% vs LAR, 76±5%; analysis of variance, P = .03). CONCLUSIONS: The results of this preliminary study suggest that residence at moderate altitude allows maintenance of higher SpO2 and reduces risk of developing AMS during rapid ascent to higher altitude.

Thoraco-abdominal coordination and performance during uphill running at altitude.

INTRODUCTION: Running races on mountain trails at moderate-high altitude with large elevation changes throughout has become increasingly popular. During exercise at altitude, ventilatory demands increase due to the combined effects of exercise and hypoxia. AIM: To investigate the relationships between thoraco-abdominal coordination, ventilatory pattern, oxygen saturation (SpO2), and endurance performance in runners during high-intensity uphill exercise. METHODS: Fifteen participants (13 males, mean age 42±9 yrs) ran a "Vertical Kilometer," i.e., an uphill run involving a climb of approximately 1000 m with a slope greater than 30%. The athletes were equipped with a portable respiratory inductive plethysmography system, a finger pulse oximeter and a global positioning unit (GPS). The ventilatory pattern (ventilation (VE), tidal volume (VT), respiratory rate (RR), and VE/VT ratio), thoraco-abdominal coordination, which is represented by the phase angle (PhA), and SpO2 were evaluated at rest and during the run. Before and after the run, we assessed respiratory function, respiratory muscle strength and the occurrence of interstitial pulmonary edema by thoracic ultrasound. RESULTS: Two subjects were excluded from the respiratory inductive plethysmography analysis due to motion artifacts. A quadratic relationship between the slope and the PhA was observed (r = 0.995, p = 0.036). When the slope increased above 30%, the PhA increased, indicating a reduction in thoraco-abdominal coordination. The reduced thoraco-abdominal coordination was significantly related to reduced breathing efficiency (i.e., an increased VE/VT ratio; r = 0.961, p = 0.038) and SpO2 (r = -0.697, p<0.001). Lower SpO2 values were associated with lower speeds at 20%≥slope≤40% (r = 0.335, p<0.001 for horizontal and r = 0.36, p<0.001 for vertical). The reduced thoraco-abdominal coordination and consequent reduction in SpO2 were associated with interstitial pulmonary edema. CONCLUSION: Reductions in thoraco-abdominal coordination are associated with a less efficient ventilatory pattern and lower SpO2 during uphill running. This fact could have a negative effect on performance.

Respiratory muscle impairment in dialysis patients: can minimal dose of exercise limit the damage? A Preliminary study in a sample of patients enrolled in the EXCITE trial.

AIM: Skeletal muscle atrophy and dysfunction with associated weakness may involve the respiratory muscles of dialysis patients. We evaluated the effect of moderate-intensity exercise on lung function and respiratory muscle strength. METHODS: Fifty-nine patients (25 F, aged 65 ± 13 years) from two centers participating in the multicenter randomized clinical trial EXerCise Introduction To Enhance Performance in Dialysis (EXCITE) were studied. Subjects were randomized into a prescribed exercise group (E), wherein subjects performed two 10-min walking sessions every second day at an intensity below the self-selected speed, or a control group (C) with usual care. Physical performance was assessed by the 6-min walk test (6MWT). Patient lung function and respiratory muscle strength were evaluated by spirometry and maximal inspiratory pressure (MIP), respectively. RESULTS: Forty-two patients (14 F) completed the study. At baseline, the groups did not differ in any parameters. In total, 7 patients (4 in E; 3 in C) showed an obstructive pattern. The pulmonary function parameters were significantly correlated with 6MWT but not with any biochemical measurements. Group E safely performed the exercise program. At follow-up, the spirometry parameters did not change in either group. A deterioration of MIP (-7 %; p = 0.008) was observed in group C, but not in group E (+3.3 %, p = ns). In E, an increase of 6MWT was also found (+12 vs. 0 % in C; p = 0.038). CONCLUSION: In dialysis patients, a minimal dose of structured exercise improved physical capacity and maintained a stable respiratory muscle function, in contrast to the control group where it worsened.

Heart rate variability during sleep at high altitude: effect of periodic breathing.

BACKGROUND: Heart rate variability (HRV) during sleep in normal subjects at high altitude shows a decrease in parasympathetic tone associated with an increase in the sympathetic one, which tends to be reversed with acclimatization. However, periodic breathing (PB) during sleep may influence this effect detected by HRV spectral analysis. PURPOSE: The aim of our study was to investigate HRV during sleep periodic breathing (PB) at high altitude in normal subjects at two different times of acclimatization, i.e., two different levels of hypoxemia. METHODS: Recordings of six healthy climbers (aged between 33 and 40 years), at sea level (SL) and at Everest North Base Camp (5180 m), during the first (BC1) and the tenth (BC2) overnight unattended polygraphy, were analyzed. PB was commonplace in all subjects at high altitude to a variable extent. At SL and at BC1 and BC2, HRV was evaluated overnight and separately during clear regular breathing (RB) and PB. RESULTS: A mean overnight beat-by-beat series interval (RR) reduction at acute environmental hypoxic exposure that resumed to SL values after 10-day sojourn was observed. This reduction was mostly due to RR during RB, while during PB, RR values were not different from SL. Higher peaks of tidal volume were associated with higher HRV. CONCLUSIONS: The present study shows that in healthy subjects, PB with central apneas increases the amplitude of RR oscillations, and these oscillations are tightly related to respiratory amplitude. Oxygenation does not influence this phenomenon. Therefore, oscillations in ventilation itself should be taken into account when investigating HRV.

Respiratory muscle training with normocapnic hyperpnea improves ventilatory pattern and thoracoabdominal coordination, and reduces oxygen desaturation during endurance exercise testing in COPD patients.

BACKGROUND: Few data are available about the effects of respiratory muscle training with normocapnic hyperpnea (NH) in COPD. The aim is to evaluate the effects of 4 weeks of NH (Spirotiger(®)) on ventilatory pattern, exercise capacity, and quality of life (QoL) in COPD patients. METHODS: Twenty-six COPD patients (three females), ages 49-82 years, were included in this study. Spirometry and maximal inspiratory pressure, St George Respiratory Questionnaire, 6-minute walk test, and symptom-limited endurance exercise test (endurance test to the limit of tolerance [tLim]) at 75%-80% of peak work rate up to a Borg Score of 8-9/10 were performed before and after NH. Patients were equipped with ambulatory inductive plethysmography (LifeShirt(®)) to evaluate ventilatory pattern and thoracoabdominal coordination (phase angle [PhA]) during tLim. After four supervised sessions, subjects trained at home for 4 weeks - 10 minutes twice a day at 50% of maximal voluntary ventilation. The workload was adjusted during the training period to maintain a Borg Score of 5-6/10. RESULTS: Twenty subjects completed the study. After NH, maximal inspiratory pressure significantly increased (81.5±31.6 vs 91.8±30.6 cmH2O, P<0.01); exercise endurance time (+150 seconds, P=0.04), 6-minute walk test (+30 meters, P=0.03), and QoL (-8, P<0.01) all increased. During tLim, the ventilatory pattern changed significantly (lower ventilation, lower respiratory rate, higher tidal volume); oxygen desaturation, PhA, and dyspnea Borg Score were lower for the same work intensity (P<0.01, P=0.02, and P<0.01, respectively; one-way ANOVA). The improvement in tidal volume and oxygen saturation after NH were significantly related (R (2)=0.65, P<0.01). CONCLUSION: As expected, NH improves inspiratory muscle performance, exercise capacity, and QoL. New results are significant change in ventilatory pattern, which improves oxygen saturation, and an improvement in thoracoabdominal coordination (lower PhA). These two facts could explain the reduced dyspnea during the endurance test. All these results together may play a role in improving exercise capacity after NH training.

Long-term monitoring of oxygen saturation at altitude can be useful in predicting the subsequent development of moderate-to-severe acute mountain sickness.

OBJECTIVE: The use of pulse oximetry (Spo2) to identify subjects susceptible to acute mountain sickness (AMS) is the subject of debate. To obtain more reliable data, we monitored Spo2 for 24 hours at altitude to investigate the ability to predict impending AMS. METHODS: The study was conducted during the climb from Alagna (1154 m) to Capanna Regina Margherita (4559 m), with an overnight stay in Capanna Gnifetti (3647 m). Sixty subjects (11 women) were recruited. Each subject was fitted with a 24-hour recording finger pulse oximeter. The subjects rode a cable car to 3275 m and climbed to 3647 m, where they spent the night. RESULTS: In the morning, 24 subjects (6 women) had a Lake Louise Questionnaire score (LLS) ≥ 3 (AMS(+)), and 15 subjects (4 women) exhibited moderate-to-severe disease (LLS ≥ 5 = AMS(++)). At Alagna, Spo2 did not differ between the AMS(-) and AMS(+) subjects. At higher stations, all AMS(+) subjects exhibited a significantly lower Spo2 than did the AMS(-) subjects: at 3275 m, 85.4% vs 87.7%; resting at 3647 m, 84.5% vs 86.4%. The receiver operating characteristics curve analysis resulted in a rather poor discrimination between the AMS(-) subjects and all of the AMS(+) subjects. With the cutoff LLS ≥ 5, the sensitivity was 86.67%, the specificity was 82.25%, and the area under the curve was 0.88 (P < .0001) for Spo2 ≤ 84% at 3647 m. CONCLUSIONS: We conclude that AMS(+) subjects exhibit a more severe and prolonged oxygen desaturation than do AMS(-) subjects starting from the beginning of altitude exposure, but the predictive power of Spo2 is accurate only for AMS(++).