[Cardiac function in secondary defect of interatrial septum and effects of its correction by Amplatzer occluder].

AIM: To study with impulse-wave Doppler and impulse-wave tissue Doppler investigation left and right ventricular (LV, RV) function in two age groups of patients suffering from an interatrial septum defect (ISD) before and two years after transcatheter correction. MATERIAL AND METHODS: 34 patients (20 females and 14 males) with secondary ISD aged 5 to 67 years were divided into two groups by age. Group 1 consisted of 11 patients aged under 16 years (mean age 10.4 +/- 0.9 years), group 2--of 23 patients over 16 (mean age 31.8 +/- 2.6 years). 30 controls were matched by age. LV and RV functions were assessed by Doppler index (DI) using impulse-wave Doppler and impulse-wave tissue Doppler investigation before the defect repair and 24 hours, 1, 3, 6, 12 and 24 months after it. RESULTS: Indexed stretch-diameter of the defect in group 1 was 13.1 +/- 1.7 mm/m2, in group 2--11.7 +/- 0.8 mm/m2 (p > 0.05). Size of the occluder to body surface area was larger in group 1 patients (15.2 +/- 1.7 and 14.6 +/- 0.98 mm/m2, respectively; p > 0.05). There was initial LV and RV dysfunction in patients of both the groups. After transcatheter correction of ISD, RV DI normalized after 3 months after the defect correction in group 1, in group 2--only in 24 months. By linear RV function examination, after ISD correction DI reached control level in group 1 12 months, in group 2--24 months after surgery. LV DI in both groups did not differ from that of healthy controls 24 months after surgery. Lateral wall LV linear function examination after the defect correction discovered DI change after 1 month in group 1 (a 12% decrease; p < 0.01); control values were achieved only 2 years after surgery. In patients of group 2 DI reduced only 6 months after correction (by 14.5+ACUAOw- p +ADw- 0.01) and reached control values in 24 months. Tissue Doppler investigation of the mitral valve fibrous ring on the side of the interventricular septum after the occluder implantation showed that DI significantly decreased in group 1 in 1 month (by 9%). In group 2--in 6 months by 10% (p < 0.05). In 24 months DI achieved control values in both the groups. CONCLUSION: Patients with ISD have LV and RV dysfunction. Recovery of LV and RV functional activity after transcatheter repair of the defect with Amplatzer occluder takes place later (for 12-24 months), in children recovery is faster than in adults.

Noninvasive and invasive evaluation of pulmonary arterial pressure in highlanders.

The purpose of the present study was to evaluate Doppler echocardiography for the detection of pulmonary hypertension in high-altitude inhabitants. In total, 60 (55 male) patients aged 18-71 yrs were recruited from an ECG screening programme applied to 1,430 inhabitants living at an altitude of 2,500-3,600 m in Kyrgyzstan. Of these, 44 met ECG criteria for right ventricular hypertrophy. All underwent Doppler echocardiography followed by a cardiac catheterisation within 7 days of arrival in Bishkek (Kyrgyzstan; altitude 760 m). Pulmonary flow acceleration time and the maximum velocity of tricuspid regurgitation were measured. Sufficient quality tricuspid regurgitant jets were recovered in only 28% of the patients. Therefore, pulmonary artery pressure was estimated from the pulmonary flow acceleration time, which was recovered in 100% of the patients. It was found that 37 (62%) of the patients had pulmonary hypertension on echocardiography. Pulmonary hypertension was confirmed in 29 patients on catheterisation. Pulmonary hypertension was detected with 70% sensitivity and 88% specificity by echocardiography, as compared to 59% sensitivity and 81 % specificity by ECG. The correlation coefficient between echocardiography and catheterisation studies was r(2) = 0.78. It is concluded that a combination of ECG and echocardiography may be useful for screening high-altitude pulmonary hypertension.

[Analysis of the amount of plasma cholesterol and triglycerides in patients with coronary heart disease].

Fluorescence technique was used to study the time course of changes in the amount of blood cholesterol and triglycerides (C+TG) in 43 patients with Q- and non-Q-wave myocardial infarction (MI) on days 1, 2, 3, and 10 of the disease, in 82 patients with chronic coronary heart disease (CHD), and in 43 apparently healthy donors. Within the first 3 days of the disease, the level of C+TG in the patients with acute MI (AMI) was significantly lower than that in the patients with chronic CHD and in the donors. By day 10 of their hospital stay, the level of lipids in patients with AMI increased and reached the levels observed in the control group.

[Remodeling of the heart after transcatheter repair of the secondary interatrial defect with amplatzer occluder].

AIM: To ascertain the effects of transcatheter repair of the secondary interatrial defect (IAD) with Amplatzer occluder on heart remodeling in respect to the patient's age. MATERIAL AND METHODS: Transcatheter repair of the secondary IAD was made in 64 patients. Two groups were formed by the patients' age: group 1--age under 16 years (mean age 9 +/- 0.6 years) and group 2--age over 16 years (mean age 32 +/- 1.8 years). The control group consisted of 30 healthy subjects matched by age. Echocardiography measured size and volumes of the heart chambers, intracardiac hemodynamics before treatment of the defect and 24 hours, 1, 3, 6, 12 and 24 months after it. RESULTS: The indexed diameter of the defect in group 1 was 16.5 +/- 1.6 mm/m2, in group 2--13.7 +/- 0.7 mm/m2 (p > 0.05). The size of the occluder, in relation to the surface area, was 20 +/- 1.5 and 16 +/- 0.8 mm/m2, respectively (p < 0.05). 24 hours after the defect repair the right ventricle volume reduced by 29% in group 1 and by 21%--in group 2. The right atrium volume reduced significantly also. Mean pulmonary arterial pressure (PAP) in both groups diminished from 22 +/- 0.7 to 19 +/- 0.7 mmHg and from 24 +/- 1.0 to 20 +/- 0,8 mmHg, respectively. The left atrium decreased by 34 and 32%, respectively (p < 0.001). Remodeling reduced RV-LV in both groups by 22 and 23% (p < 0.001), respectively. 3 months after the defect repair all the indices reached control values. 12 months after the correction hemodynamics in the patients was the same with the healthy examinees. The time and degree of reduction of the right heart were similar in the groups, the volumes diminished by about 50%. 12 months after the repair in 4 of 18 patients of group 2 (22%) the right atrium and ventricle were larger than in healthy subjects though less than before the repair. CONCLUSION: Transcatheter repair of the secondary IAD with Amplatzer catheter leads to early noticeable reduction of the right heart. The type of the changes is similar in both age groups and does not depend on the size of the implanted occluder. Not all the patients over 16 years of age achieve normal sizes of the RV and RA 12 months after the defect correction.

[Effect of theophylline on respiratory function in patients with chronic obstructive lung disease].

The purpose of the investigation was to study the effects of small (200-mg) and mean (600-mg) daily doses of theophylline on respiratory function and the quality of life in patients with chronic obstructive lung disease during its relatively long-term therapy. By the end of the third month of therapy, dyspnea ameliorated and life quality increased in both groups of patients receiving both small and mean doses of theophylline. This was accompanied by the improved parameters of bronchial patency. Thus, forced expiratory volume in one second increased up to 70.4 +/- 3.9 and to 78.2 +/- 4.8%, respectively, as compared to the baseline volumes that were equal to 54.2 +/- 4.3 and 58.4 +/- 4.7%. It should be noted that these effects were more pronounced in the mean daily theophylline dosage regimen. Relatively long-term therapy with theophylline in daily doses of 200 and 600 mg was well tolerated. The occurrence of minimum side effects did not prevent the drug from being used long in any case.

Autofluorescence of low-density lipoproteins modified as a result of autooxidation.

Autooxidation of low-density lipoproteins during incubation at 37 degrees C was accompanied by accumulation of LPO products, decrease in UV autofluorescence (FUV), and increase in autofluorescence in the visible band (FVIS). The degree of low-density lipoprotein modification was estimated by calculating the FVIS/FUV ratio. A positive correlation was revealed between this ratio and concentration of thiobarbituric acid-reactive LPO products (r=0.76, p<0.001). Autooxidation of low-density lipoproteins increased availability of tryptophanyls for fluorescence quenchers and inductive resonance energy transfer from tryptophanyls to adducts formed in the reaction of apoprotein and LPO products. These changes probably play a role in the decrease in FUV.

[I/D relationship between polymorphism of ACE gene and progression of chronic glomerulonephritis].

AIM: To study prevalence of angiotensin-converting enzyme (ACE) gene polymorphism and its correlation with ACE level in Kyrgyz population suffering from chronic glomerulonephritis (CGN); to ascertain CGN progression and survival with reference to the genotype of ACE gene. MATERIAL AND METHODS: The above parameters were investigated in 76 CGN patients (mean age 34.1 +/- 1.9 years) and 48 healthy controls matched by sex and age. Amplification of the polymorphic site of the ACE gene was made with polymerase chain reaction. Spectrofluorimetry measured ACE concentration in the serum. Progression of CGN was assessed by reciprocal creatinine. Survival of the patients was calculated according to the Kaplan-Meyer method. RESULTS: The ACE genotype distribution corresponded to the Hardi-Weinberg equilibrium. However, a significant difference in the frequency of genotypes and alleles between CGN and control patients was not revealed. The activity of serum ACE in CGN and healthy subjects was noticeably higher in DD genotype than that in genotypes II and ID (P < 0.02). The former had a significantly higher level of total cholesterol and much lower glomerular filtration rate in a rapid progression of the disease estimated by reciprocal creatinine and higher 5- and 10-year survival compared to genotypes II and ID (P < 0.05). CONCLUSION: Development of CGN is not associated with any genotype of ACE gene in Kyrgyz population. At the same time, deletion polymorphism of ACE gene may serve as a predictor for CGN progression.

Phosphodiesterase type 5 and high altitude pulmonary hypertension.

BACKGROUND: This study explored phosphodiesterase type 5 (PDE5) inhibition as a strategy for treating high altitude pulmonary arterial hypertension (HAPH). METHODS: 689 subjects (313 men) of mean (SD) age 44 (0.6) years living above 2500 m were screened for HAPH by medical examination and electrocardiography, and 188 (27%) met the criteria for right ventricular hypertrophy. 44 underwent cardiac catheterisation and 29 (66%) had a resting mean pulmonary artery pressure (PAP) above 25 mmHg. 22 patients with a raised mean PAP were randomised to receive sildenafil (25 or 100 mg) or matching placebo taken 8 hourly for 12 weeks. RESULTS: At 3 months, patients on sildenafil 25 mg 8 hourly (n = 9) had a significantly (p = 0.018) lower mean PAP (-6.9 mmHg) at the end of the dosing interval than those on placebo (n = 8) (95% CI -12.4 to -1.3). The treatment effect for sildenafil 100 mg 8 hourly (n = 5) compared with placebo was -6.4 mm Hg (95% CI -12.9 to 0.1). Both doses improved 6 minute walk distance, the lower dose by 45.4 m (95% CI 11.5 to 79.4; p = 0.011) and the higher dose by 40.0 m (95% CI 0.2 to 79.8; p = 0.049). Sildenafil was well tolerated. Necroscopic lung specimens from three subjects with HAPH showed abundant PDE5 in the muscular coat of remodelled pulmonary arterioles. CONCLUSIONS: PDE5 is an attractive drug target for the treatment of HAPH and a larger study of the long term effects of PDE5 inhibition in HAPH is warranted.

[Ethnic differences in apolipoprotein B levels in hyperlipidemia in Russian and Kirghiz populations]. / Etnicheskie osobennosti v urovne apolipoproteina B pri giperlipidemiiakh u russkikh i kirgizov.

AIM: To evaluate the levels of apolipoprotein B (apo-B) and coronary heart disease (CHD) risk factors in Russians and the Kirghiz with primary hyperlipidemia (PHL). MATERIAL AND METHODS: Lipid spectrum of the blood (LDLP and HDLP cholesterol, total cholesterol, triglycerides), apo-B, CHD risk factors were studied in 60 Russian and 75 Kirghis patients with PHL aged 28 to 67 years (mean age 50.0 +/- 7.59 years, 56 females and 79 males). RESULTS: In Russians a mean level of LDLP cholesterol and apo-B was significantly higher than in Kirghiz patients (3.95 +/- 1.29 mmol/l vs 3.51 +/- 1.17 mmol/l, p = 0.042; 173.3 +/- 57.3 mg/dl vs 145.5 +/- 49.3 mg/dl, p = 0.003, respectively). CHD in both ethnic groups occurred with similar rates. The multifactorial regression analysis shows that an apo-B concentration can serve an independent risk factor associated with CHD in the Kirghiz population (beta = 0.25, p = 0.03) while in Russians living in Kirghizia this factor is a low content of HDLP cholesterol (beta = -0.25, p = 0.05).

Changes in surface charge of low-density lipoproteins during oxidative modification.

The negative surface charge of low-density lipoproteins increased during their oxidative modification induced by autooxidation at 37 degrees C. The degree of changes depended on the time of autooxidation: the surface charge remained practically unchanged after short-term oxidation (6-h incubation), but then progressively increased and after 24-h oxidation it 2-fold surpassed the initial level. Long-term incubation of low-density lipoproteins in the presence of EDTA inhibiting lipid peroxidation did not change their surface charge. These changes probably contribute to atherogenic activity of oxidized low-density lipoproteins. The degree of oxidative modification of low-density lipoproteins was precisely estimated using fluorescence probes.

The Eurasian heartland: a continental perspective on Y-chromosome diversity.

The nonrecombining portion of the human Y chromosome has proven to be a valuable tool for the study of population history. The maintenance of extended haplotypes characteristic of particular geographic regions, despite extensive admixture, allows complex demographic events to be deconstructed. In this study we report the frequencies of 23 Y-chromosome biallelic polymorphism haplotypes in 1,935 men from 49 Eurasian populations, with a particular focus on Central Asia. These haplotypes reveal traces of historical migrations, and provide an insight into the earliest patterns of settlement of anatomically modern humans on the Eurasian continent. Central Asia is revealed to be an important reservoir of genetic diversity, and the source of at least three major waves of migration leading into Europe, the Americas, and India. The genetic results are interpreted in the context of Eurasian linguistic patterns.

Sildenafil inhibits hypoxia-induced pulmonary hypertension.

BACKGROUND: This study investigated the effect of the phosphodiesterase 5 inhibitor sildenafil on the pulmonary vascular response to hypoxia in humans and mice. METHODS AND RESULTS: In a randomized, double-blind study, sildenafil 100 mg or placebo was given orally to 10 healthy volunteers 1 hour before breathing 11% O(2) for 30 minutes. Pulmonary artery pressure (PAP) was measured with an indwelling right heart catheter. The acute 56% increase in mean PAP produced by hypoxia during placebo treatment (mean PAP [mean+/-SD mm Hg]: normoxia 16.0+/-2.1 versus hypoxia 25.0+/-4.8) was almost abolished by sildenafil (normoxia 16.0+/-2.1 versus hypoxia 18.0+/-3.6), with no significant effect on systemic blood pressure. In the isolated perfused lung of wild-type and endothelial nitric oxide synthase (eNOS)-deficient mice, sildenafil markedly blunted acute hypoxic pulmonary vasoconstriction. Wild-type mice dosed orally with the drug (25 mg. kg(-1). d(-1)) throughout 3 weeks of exposure to hypoxia (10% O(2)) exhibited a significant reduction in right ventricular systolic pressure (placebo versus sildenafil: 43.3+/-9.9 versus 29.9+/-9.7 mm Hg, P<0.05) coupled with a small reduction in right ventricular hypertrophy and inhibition of pulmonary vascular remodeling. In eNOS mutant mice, sildenafil attenuated the increase in right ventricular systolic pressure but without a significant effect on right ventricular hypertrophy or vascular remodeling. CONCLUSIONS: Sildenafil attenuates hypoxia-induced pulmonary hypertension in humans and mice and offers a novel approach to the treatment of this condition. The eNOS-NO-cGMP pathway contributes to the response to sildenafil, but other biochemical sources of cGMP also play a role. Sildenafil has beneficial pulmonary hemodynamic effects even when eNOS activity is impaired.

The quality of sleep and periodic breathing in healthy subjects at an altitude of 3,200 m.

The medical risks of travel and stay at high altitude are well known. Many more people travel for recreation to lower but still significant altitudes. To investigate the quality of sleep and sleep-related breathing disorders (SRBD) at that altitude we performed full polysomnography in nine young volunteers at lowland (760 m above sea level) on the first and sixth night after ascent to 3,200 m. There have been few studies on such populations. The subjects were nonsmoking healthy males aged 20.3 +/- 3.5 years with normal spirometry and arterial blood gas measurements performed at low altitude. Although there was no statistically significant difference in the duration of stages and sleep quality between low altitude night and both nights at high altitude as assessed by percent of sleep spent in stage 1, 2, 3+4 NREM, and REM sleep, total sleep time (TST), and sleep efficiency; the number of arousals and awakenings doubled at high altitude. There was no periodic breathing (PB) during sleep, except in isolated central events of SRBD, at low altitude. PB appeared at altitude mostly during NREM sleep and its intensity remained stable throughout the study period. Individual variations of PB intensity were high, ranging from 0.1 to 24% of TST. There were also some episodes of obstructive apnea and hypopnea during sleep at high altitude (p < 0.001). Mean SaO2 was lower during the study nights at high altitude when compared with low altitude. There were some signs of ventilatory acclimatization as shown by a higher mean SaO2 during the sixth compared with the first night at altitude (p < 0.001). We conclude that the sleep quality at the altitude of 3,200 m remains satisfactory when compared to low altitude. There is high individual variability in intensity of PB at that altitude.

[Quality of sleep and periodic breathing in healthy individuals working at an altitude of 3700 meters]. / Jakosc snu i oddychanie okresowe u ludzi zdrowych pracujacych na wysokosci 3700 metrów.

We performed full polysomnography (PSG) in 7 healthy miners of Kyrghyz origin (mean age 25 +/- 6 years) working in 2 weeks shifts at Kumtor gold mines at the elevation of 4200 m. They slept in comfortable dormitories situated at 3700 m. To avoid acute mountain sickness all subjects received acetazolamide 3 x 0.25 daily during 2 days preceding ascent and during 2 days at altitude: PSG was performed three times: at 760 m (1) and on the 1st (2) and 7th night (3) after rapid ascent (aircraft) to high altitude using SomnoTrac 4250 sleep laboratory. We found that sleep efficiency was good at lowland and in the mountains averaging 81.79% and 84% respectively. Although there were no significant differences in percentage of sleep stages and of total sleep time between lowland and both nights at high altitude, arousals and awakenings were more frequent in the mountains. Episodes of periodic breathing (PB) appeared at high altitude. There was a large individual variability in PB on both nights at altitude. The time spent in PB ranged from 4 to 30 minutes during the first night at altitude and from 3 to 17 minutes during the second one. PB appeared mainly during non-REM sleep and aggravated arterial blood desaturation.

[Three week stay at a height of 3700-4200 m. causes mild pulmonary hypertension in healthy men]. / Trzytygodniowy pobyt na wysokosci 3700-4200 m. wywoluje lagodne nadcisnienie plucne u zdrowych mezczyzn.

High altitude hypoxia leads to development of hypoxic pulmonary hypertension. We studied 27 healthy caucasian subjects aged 24 to 59 years, mean 41.6 +/- 9 y, working on 4 week shifts at the Kumtor gold mines at the altitude of 3700-4200 m. Pulmonary circulation was studied twice by Echo-Doppler using Toshiba SSD-160. The first investigation was performed at the level of 730 m at the end of 4 week holiday spent in the lowland, the second investigation on the 23rd day at altitude. Pulmonary artery acceleration time decreased from 131 +/- 14 ms to 105 +/- 14 ms (p < 0.001). Calculated pulmonary arterial mean pressure increased from 15.1 +/- 2 to 25.4 +/- 8 mmHg (p < 0.001). Right ventricular preejection period increased from 93 +/- 14 to 102 +/- 19 ms (p < 0.05). Other echo variable did not change. We conclude that healthy subjects submitted to 3 week exposure to high altitude hypoxia (oxygen pressure in the inspired air 82-88 mmHg), developed mild pulmonary hypertension, regressing after recovery at the lowland.

[Quality of sleep and periodic breathing during sleep in healthy persons at a height of 3200 meters]. / Jakosc snu oraz oddychanie okresowe podczas snu u ludzi zdrowych na wysokosci 3200 metrów.

In order to investigate quality of sleep and sleep-related breathing disorders (SRBD) at high altitude we performed full polysomnography in 9 young healthy volunteers at lowland (760 m above see level) and on the 1st and 6th night after the ascent to the altitude of 3200 m. The subjects were non-smoking males aged 20.3 +/- 3.5 years with normal spirometry and arterial blood gas measurements performed at low altitude. We found no statistical difference in sleep quality between low and both nights at high altitude as considered by % of stages 1, 2, 3 + 4 non-REM, and REM sleep, total sleep time, sleep efficiency, and number of awakenings+arousals. There was no periodic breathing (PB) during sleep but some central events of SRBD at low altitude. PB appeared at high altitude mostly during non-REM sleep and remained stable throughout the study period. There were also some obstructive SRBD found during high altitude nights. Mean SaO2 was lower during both nights at high altitude when compared to low altitude (p < 0.00001). It was higher during the 6th than during the 1st night at altitude (p < 0.0001). Minimum SaO2 was comparable during low altitude and 6th night at altitude and was lower during the 1st altitude night (p < 0.02). We conclude that sleep quality at the altitude of 3200 m remains unchanged when compared to lowland. There is high individual variability in PB at altitude and its intensity is negligible.

[Effect of altitude on blood oxygenation during sleep in patients with bronchial asthma]. / Wplyw wysokosci na utlenowanie krwi w czasie snu u chorych na astme oskrzelowa.

The aim of our study was to investigate the severity of overnight arterial blood desaturations in patients with asthma at the altitude of 3200 meters above sea level. 12 asthmatics and 12 healthy controls were investigated. Three overnight pulsoximetries were performed in all subjects, one at the lowland and on the 1st and 5th night at the altitude. Mean SaO2 at the lowland was significantly lower in asthmatics than in the controls (p < 0.01). After the ascent to high altitude severe fall in mean SaO2 was noted in both groups (from 94.3% to 85.8% in asthmatics and from 97.1% to 88.7% in controls) (p < 0.001 for both groups). After few days of acclimatization mean SaO2 rose to 88.8% in asthmatics and to 91.3% in controls, but was still significantly lower than at the lowland (p < 0.001 for both groups). At the altitude differences in mean SaO2 between two groups were not statistically significant. We conclude that severity of overnight desaturations at high altitude do not vary between asthmatics with impaired respiratory function and healthy subjects.

[The rehabilitation under alpine conditions of the participants in the cleanup of the accident at the Chernobyl Atomic Electric Power Station who are ill with chronic bronchitis]. / Reabilitatsiia v usloviiakh vysokogor'ia uchastnikov likvidatsii avarii na Chernobyl'skoi AES, bol'nykh khronicheskim bronkhitom.

24 patients exposed to low-dose radiation after the Chernobyl accident were examined before and after 24-day treatment of chronic bronchitis in the high-altitude rehabilitation center (3200 m above the sea level) in Tien Shan. Sanogenic alpine climate improved the patients' general condition, physical performance and lung ventilation, corrected compromised immunity. After high-altitude adaptation tracheobronchial inflammation alleviated, cytologic composition and surface activity of bronchoalveolar fluid returned to normal. Therefore, high-altitude treatment of Chernobyl accident victims with chronic bronchitis is effective and can be recommended for such patients.

[Periodic breathing during sleep at high altitudes in patients with bronchial asthma]. / Oddychanie okresowe w czasie snu w wysokich górach u chorych na astme oskrzelowa.

Earlier we found that asthmatic patients treated at a high altitude sanatorium (3.200 m) had numerous episodes of arterial blood desaturation during the night. To investigate if periodic breathing (PB) was responsible for those episode we studied 5 asthmatics (A) (mean age 34 yrs) and 3 healthy controls (C) (mean age 28 yrs) using MESAM 4, a simple, portable system recording breathing sounds, heart frequency, arterial blood saturation and body position. A and C subjects were first investigated at low altitude (760 m). There was no PB at 760 m in either group. At high altitude MESAM 4 recordings were performed on the 2nd and the 7th night after the ascent. On the 2nd night in the A group subjects the number of PB cycles averaged 37.2 (22-54) occupying 3.2% (2-5%) of estimated sleep time. The number of no-PB episodes was 52.4 (23-109). In the C group subjects the number of PB cycles was 83.6 (10-147) occupying 9% (1-14%) of estimated sleep time. The number of no-PB episodes averaged 45.6 (6-84). On the 7th night in A the number of PB cycles was 46.6 (15-69) occupying 4% (1-7%) of estimated sleep time. The number of no-PB was 54.8 (13-147). In C the number of PB cycles averaged 29.3 (12-59) occupying 3.3% (2-6%) of estimated sleep time. The number of no-PB was 20.3 (9-37). We conclude that majority of desaturations during sleep in asthmatics at altitude of 3.200 m was not related to PB; the mechanisms of these desaturations require more investigations.