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Concept: Respiratory physiology


Slow deep breathing improves blood oxygenation (Sp(O2)) and affects hemodynamics in hypoxic patients. We investigated the ventilatory and hemodynamic effects of slow deep breathing in normal subjects at high altitude. We collected data in healthy lowlanders staying either at 4559 m for 2-3 days (Study A; N = 39) or at 5400 m for 12-16 days (Study B; N = 28). Study variables, including Sp(O2) and systemic and pulmonary arterial pressure, were assessed before, during and after 15 minutes of breathing at 6 breaths/min. At the end of slow breathing, an increase in Sp(O2) (Study A: from 80.2±7.7% to 89.5±8.2%; Study B: from 81.0±4.2% to 88.6±4.5; both p<0.001) and significant reductions in systemic and pulmonary arterial pressure occurred. This was associated with increased tidal volume and no changes in minute ventilation or pulmonary CO diffusion. Slow deep breathing improves ventilation efficiency for oxygen as shown by blood oxygenation increase, and it reduces systemic and pulmonary blood pressure at high altitude but does not change pulmonary gas diffusion.

Concepts: Oxygen, Blood, Heart, Respiratory physiology, Blood pressure, Artery, Vein, Pulse oximetry


BACKGROUND: Enhancing athletic performance is a great desire among the athletes, coaches and researchers. Mint is one of the most famous natural herbs used for its analgesic, anti-inflammatory, antispasmodic, antioxidant, and vasoconstrictor effects. Even though inhaling mint aroma in athletes has been investigated, there were no significant effects on the exercise performance. METHODS: Twelve healthy male students every day consumed one 500 ml bottle of mineral water, containing 0.05 ml peppermint essential oil for ten days. Blood pressure, heart rate, and spirometry parameters including forced vital capacity (FVC), peak expiratory flow rate (PEF), and peak inspiratory flow (PIF) were determined one day before, and after the supplementation period. Participants underwent a treadmill-based exercise test with metabolic gas analysis and ventilation measurement using the Bruce protocol. RESULTS: The FVC (4.57 +/- 0.90 vs. 4.79 +/- 0.84; p < 0.001), PEF (8.50 +/- 0.94 vs. 8.87 +/- 0.92; p < 0.01), and PIF (5.71 +/- 1.16 vs. 6.58 +/-1.08; p < 0.005) significantly changed after ten days of supplementation. Exercise performance evaluated by time to exhaustion (664.5 +/- 114.2 vs. 830.2 +/- 129.8 s), work (78.34 +/-32.84 vs. 118.7 +/- 47.38 KJ), and power (114.3 +/- 24.24 vs. 139.4 +/- 27.80 KW) significantly increased (p < 0.001). In addition, the results of respiratory gas analysis exhibited significant differences in VO2 (2.74 +/- 0.40 vs. 3.03 +/- 0.351 L/min; p < 0.001), and VCO2 (3.08 +/- 0.47 vs. 3.73 +/- 0.518 L/min; p < 0.001). CONCLUSIONS: The results of the experiment support the effectiveness of peppermint essential oil on the exercise performance, gas analysis, spirometry parameters, blood pressure, and respiratory rate in the young male students. Relaxation of bronchial smooth muscles, increase in the ventilation and brain oxygen concentration, and decrease in the blood lactate level are the most plausible explanations.

Concepts: Asthma, Atherosclerosis, Respiratory physiology, Medical signs, Spirometry, Exercise physiology, Vital capacity, Peak flow meter


Chronic Obstructive Pulmonary Disease (COPD) is characterized by high morbidity and mortality. It remains unknown which aspect of lung function carries the most prognostic information and if simple spirometry is sufficient.Survival was assessed in COPD outpatients whose data had been added prospectively to a clinical audit database from the point of first full lung function testing including spirometry, lung volumes, carbon monoxide diffusion capacity and arterial blood gases. Variables univariately associated with survival were entered into a multivariate Cox proportional hazard model.604 patients were included (mean age 61.9±9.7 years, forced expiratory volume in 1 second 37±18.1%predicted, 62.9% males); 229(37.9%) died during a median follow-up of 83 months. Median survival was 91.9(80.8-103) months with survival rates at 3 and 5 years 0.83 and 0.66, respectively. Carbon monoxide diffusion capacity %predicted quartiles [(best quartile (>51%): HR=: 0.33; 95% CI: 0.96-0. and second quartile (51-37.3%): HR=0.52, versus lowest quartile (<27.9%))], age (HR=:1.04; 95% CI:1.02-1.06) and arterial oxygen partial pressure (HR=: 0.85;95% CI:0.77-0.94) were the only parameters independently associated with mortality.Measurement of diffusion capacity provides additional prognostic information compared to spirometry in patients under hospital follow-up and could be considered routinely.

Concepts: Oxygen, Pulmonology, Asthma, Lung, Respiratory physiology, Chronic obstructive pulmonary disease, Spirometry, Respiratory therapy


Pre-clinical data demonstrate a pivotal role for interleukin (IL)-13 in the development and maintenance of asthma. This study assessed the effects of tralokinumab, an investigational human IL-13-neutralising immunoglobulin G4 monoclonal antibody, in adults with moderate-to-severe uncontrolled asthma despite controller therapies. 194 subjects were randomised to receive tralokinumab (150, 300 or 600 mg) or placebo subcutaneously every 2 weeks. Primary end-point was change from baseline in mean Asthma Control Questionnaire score (ACQ-6; ACQ mean of six individual item scores) at week 13 comparing placebo and combined tralokinumab dose groups. Secondary end-points included pre-bronchodilator lung function, rescue β(2)-agonist use and safety. Numerical end-points are reported as mean±sd. At week 13, change from baseline in ACQ-6 was -0.76±1.04 for tralokinumab versus -0.61±0.90 for placebo (p=0.375). Increases from baseline in forced expiratory volume in 1 s (FEV(1)) were 0.21±0.38 L versus 0.06±0.48 L (p=0.072), with a dose-response observed across the tralokinumab doses tested. β(2)-agonist use (puffs per day) was decreased for tralokinumab -0.68±1.45 versus placebo -0.10±1.49 (p=0.020). The increase in FEV(1) following tralokinumab treatment remained evident 12 weeks after the final dose. Safety profile was acceptable with no serious adverse events related to tralokinumab. No improvement in ACQ-6 was observed, although tralokinumab treatment was associated with improved lung function.

Concepts: Immune system, Pulmonology, Asthma, Lung, Respiratory physiology, Chronic obstructive pulmonary disease, Spirometry, Peak flow meter


Acute lung function (LF) changes might predict an accelerated decline in LF. In this study, we investigated the association between cross-shift and longitudinal changes in forced expiratory volume in 1 s (FEV(1)) among woodworkers in a 6-year follow-up study.

Concepts: Pulmonology, Asthma, Lung, Respiratory physiology, The Association, Spirometry, Wood


BACKGROUND:: The authors tested the hypothesis that during laparoscopic surgery, Trendelenburg position and pneumoperitoneum may worsen chest wall elastance, concomitantly decreasing transpulmonary pressure, and that a protective ventilator strategy applied after pneumoperitoneum induction, by increasing transpulmonary pressure, would result in alveolar recruitment and improvement in respiratory mechanics and gas exchange. METHODS:: In 29 consecutive patients, a recruiting maneuver followed by positive end-expiratory pressure 5 cm H2O maintained until the end of surgery was applied after pneumoperitoneum induction. Respiratory mechanics, gas exchange, blood pressure, and cardiac index were measured before (TBSL) and after pneumoperitoneum with zero positive end-expiratory pressure (TpreOLS), after recruitment with positive end-expiratory pressure (TpostOLS), and after peritoneum desufflation with positive end-expiratory pressure (Tend). RESULTS:: Esophageal pressure was used for partitioning respiratory mechanics between lung and chest wall (data are mean ± SD): on TpreOLS, chest wall elastance (Ecw) and elastance of the lung (EL) increased (8.2 ± 0.9 vs. 6.2 ± 1.2 cm H2O/L, respectively, on TBSL; P = 0.00016; and 11.69 ± 1.68 vs. 9.61 ± 1.52 cm H2O/L on TBSL; P = 0.0007). On TpostOLS, both chest wall elastance and EL decreased (5.2 ± 1.2 and 8.62 ± 1.03 cm H2O/L, respectively; P = 0.00015 vs. TpreOLS), and PaO2/inspiratory oxygen fraction improved (491 ± 107 vs. 425 ± 97 on TpreOLS; P = 0.008) remaining stable thereafter. Recruited volume (the difference in lung volume for the same static airway pressure) was 194 ± 80 ml. PplatRS remained stable while inspiratory transpulmonary pressure increased (11.65 + 1.37 cm H2O vs. 9.21 + 2.03 on TpreOLS; P = 0.007). All respiratory mechanics parameters remained stable after abdominal desufflation. Hemodynamic parameters remained stable throughout the study. CONCLUSIONS:: In patients submitted to laparoscopic surgery in Trendelenburg position, an open lung strategy applied after pneumoperitoneum induction increased transpulmonary pressure and led to alveolar recruitment and improvement of Ecw and gas exchange.

Concepts: Pulmonology, Heart, Respiratory physiology, Surgery, Laparoscopic surgery, Laparoscopy, Lung volumes, Pneumoperitoneum


A 6-second spirometry test is easier than full exhalations. We compared the reliability of the ratio of the Forced expiratory volume in 1 second/Forced expiratory volume in 6 seconds (FEV1/FEV6) to the ratio of the FEV1/Forced vital capacity (FEV1/FVC) for the detection of airway obstruction.

Concepts: Longitudinal study, Respiratory physiology, Ratio, Spirometry, Obstructive lung disease, Vital capacity, Airway obstruction


The exact underlying pathomechanism of central sleep apnea with Cheyne-Stokes respiration (CSA-CSR) is still unclear. Recent studies have demonstrated an association between cerebral white matter changes and CSA. A dysfunction of central respiratory control centers in the brainstem was suggested by some authors. Novel MR-imaging analysis tools now allow far more subtle assessment of microstructural cerebral changes. The aim of this study was to investigate whether and what severity of subtle structural cerebral changes could lead to CSA-CSR, and whether there is a specific pattern of neurodegenerative changes that cause CSR. Therefore, we examined patients with Fabry disease (FD), an inherited, lysosomal storage disease. White matter lesions are early and frequent findings in FD. Thus, FD can serve as a “model disease” of cerebral microangiopathy to study in more detail the impact of cerebral lesions on central sleep apnea.

Concepts: Respiratory physiology, Lysosomal storage disease, Sleep, White matter, Sleep apnea, Abnormal respiration, Apnea, Respiration


Background Air-pollution levels have been trending downward progressively over the past several decades in southern California, as a result of the implementation of air quality-control policies. We assessed whether long-term reductions in pollution were associated with improvements in respiratory health among children. Methods As part of the Children’s Health Study, we measured lung function annually in 2120 children from three separate cohorts corresponding to three separate calendar periods: 1994-1998, 1997-2001, and 2007-2011. Mean ages of the children within each cohort were 11 years at the beginning of the period and 15 years at the end. Linear-regression models were used to examine the relationship between declining pollution levels over time and lung-function development from 11 to 15 years of age, measured as the increases in forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) during that period (referred to as 4-year growth in FEV1 and FVC). Results Over the 13 years spanned by the three cohorts, improvements in 4-year growth of both FEV1 and FVC were associated with declining levels of nitrogen dioxide (P<0.001 for FEV1 and FVC) and of particulate matter with an aerodynamic diameter of less than 2.5 μm (P= 0.008 for FEV1 and P<0.001 for FVC) and less than 10 μm (P<0.001 for FEV1 and FVC). These associations persisted after adjustment for several potential confounders. Significant improvements in lung-function development were observed in both boys and girls and in children with asthma and children without asthma. The proportions of children with clinically low FEV1 (defined as <80% of the predicted value) at 15 years of age declined significantly, from 7.9% to 6.3% to 3.6% across the three periods, as the air quality improved (P=0.001). Conclusions We found that long-term improvements in air quality were associated with statistically and clinically significant positive effects on lung-function growth in children. (Funded by the Health Effects Institute and others.).

Concepts: Asthma, Respiratory physiology, Chronic obstructive pulmonary disease, Pollution, Spirometry, Smog, Air pollution, Vital capacity


Mechanical ventilation with a tidal volume (VT) of 6 mL/kg/predicted body weight (PBW), to maintain plateau pressure (Pplat) lower than 30 cmH2O, does not completely avoid the risk of ventilator induced lung injury (VILI). The aim of this study was to evaluate safety and feasibility of a ventilation strategy consisting of very low VT combined with extracorporeal carbon dioxide removal (ECCO2R).

Concepts: Oxygen, Carbon dioxide, Pulmonology, Pneumonia, Respiratory physiology, Acute respiratory distress syndrome, Mechanical ventilation, Pulmonary contusion