Differences In Respiratory Parameters Research Articles

A wearable six-minute walk-based system to predict postoperative pulmonary complications after cardiac valve surgery: an exploratory study

In recent years, wearable devices have seen a booming development, and the integration of wearable devices with clinical settings is an important direction in the development of wearable devices. The purpose of this study is to establish a prediction model for postoperative pulmonary complications (PPCs) by continuously monitoring respiratory physiological parameters of cardiac valve surgery patients during the preoperative 6-Minute Walk Test (6MWT) with a wearable device. By enrolling 53 patients with cardiac valve diseases in the Department of Cardiovascular Surgery, West China Hospital, Sichuan University, the grouping was based on the presence or absence of PPCs in the postoperative period. The 6MWT continuous respiratory physiological parameters collected by the SensEcho wearable device were analyzed, and the group differences in respiratory parameters and oxygen saturation parameters were calculated, and a prediction model was constructed. The results showed that continuous monitoring of respiratory physiological parameters in 6MWT using a wearable device had a better predictive trend for PPCs in cardiac valve surgery patients, providing a novel reference model for integrating wearable devices with the clinic.

Respiratory health effects of e-cigarette substitution for tobacco cigarettes: a systematic review

BackgroundE-cigarettes (electronic nicotine delivery system, ENDS) have been presented as a harm reduction strategy for people who smoke tobacco cigarettes but who cannot achieve abstinence, or for those who wish to continue to enjoy nicotine and the habit of smoking. What are the health effects of the substitution of ENDS for tobacco cigarettes? This systematic review evaluates the evidence of human clinical tests on the respiratory effects of ENDS use in participants who smoke tobacco cigarettes.MethodsA registered and published protocol was developed conforming to PRISMA 2020 and AMSTAR2 standards. The literature search was conducted in PubMed, Scopus, and the CENTRAL Cochrane Library and updated to May 2022. Three supplementary searches and a grey literature search were performed. Studies were evaluated with the JBI quality tools and the Oxford Catalogue of Bias. Due to the heterogeneity (diversity) of the studies, a narrative data synthesis was performed on the test findings plus three sub-group analyses.ResultsThe review consists of sixteen studies and twenty publications. Spirometry tests comprised the majority of the data. In total, 66 respiratory test measurements were reported, out of which 43 (65%) were not significant. Statistically significant findings were mixed, with 9 tests showing improvements and 14 measuring declines, none of which was clinically relevant. Ten studies were rated at a high risk of bias, and six had some concerns primarily due to inadequate research designs and the conduct of the studies. Reporting bias was documented in thirteen studies.ConclusionsMost of the studies showed no difference in respiratory parameters. This indicates that ENDS substitution for smoking likely does not result in additional harm to respiratory health. Due to the low quality of the studies, confidence in the conclusions is rated as low. Robust studies with a longer duration and sufficient power are required to validate any potential benefits or possible harms of ENDS substitution.Registration PROSPERO #CRD42021239094, International Registered Report Identifier (IRRID): DERR1-10.2196/29084.

SERUM ELECTROLYTES AS A PROGNOSTIC MARKER IN ACUTE EXACERBATION OF CHRONIC OBSTRUCTIVE PULMONARY DISEASE

Background. COPD is the third leading cause of death. Activation of the renin-angiotensin-aldosterone system and inappropriately elevated plasma arginine vasopressin in COPD may cause hyponatremia. Hyponatremia in COPD may be a predictor of poor outcomes and patients may have high mortality. Hypokalemia in COPD may be attributed to respiratory acidosis, metabolic alkalosis, and long-standing steroid therapy. The use of beta 2 agonists may also contribute. Moreover, acute respiratory failure associated with hypokalemia may have poor outcomes Aim To compare the differences in respiratory parameters (ABG, Saturation at presentation, oxygen dependency), duration of stay, and mortality in AECOPD patients with and without dyselectrolytemia. Materials And Methods A retrospective observational study and case records of 100 patients who visited the hospital with AE of COPD from January 2019 to June 2022 were reviewed. Patients with dyselectrolytemia were considered as group I and patients without it were considered group II. Data regarding ABG, SPO2, oxygen dependency, duration of stay, mortality were collected and compared between the two groups Results And Conclusions Out of 100 patients, 60 were with dyselectrolytemia and 40 have normal electrolytes. In group, I patients 56.6% had acidotic pH (<7.35) (p=<0.007) and 83.3% had low saturation (p=0.05), 41.6% were having type II respiratory failure (p=0.01), had longer hospital stays (p=<0.0001) when compared to group II which were statistically signicant. So electrolytes should be routinely tested to prevent worse outcomes.

Can High-Flow Nasal Cannula Oxygen Therapy Improve Respiratory Status in Hospitalized Patients With COVID-19?

Introduction: High-flow nasal cannula (HFNC) is an oxygen delivery procedure for patients with respiratory disorders. The role of this oxygen therapy system in the treatment of patients with COVID-19 has not been conclusively proven. The present study evaluated the efficacy and success of HFNC in improving the clinical condition of patients with COVID-19.Methods: The statistical population of this cross-sectional study was hypoxemic patients with the COVID-19 disease. The findings of the study were obtained by reviewing patients’ records and extracting information from the hospital information system.Results: A total of 29 patients with moderate to severe COVID-19 were analyzed. Comparison of the results of blood gas analysis of these patients showed that the use of HFNC did not make a significant difference in pH (P = 0.063), PaCO2 (P = 0.135), O2sat (P = 0.999), and HCO3 (P = 0.717).Conclusion: Our study showed that the use of HFNC did not make a significant difference in respiratory parameters and the results of blood gas analysis in patients with COVID-19.

Preserved Sleep for the Same Level of Respiratory Disturbance in Children with Prader-Willi Syndrome.

Debate remains as to how to balance the use of recombinant human growth hormone (rhGH) as an important treatment in Prader-Willi syndrome (PWS) with its potential role in obstructive sleep apnea. This single-center, retrospective study assessed differences in overnight polysomnography results between children with and without PWS and changes in respiratory parameters before and after the initiation of rhGH treatment in those with PWS. Compared with age-, sex-, and body-mass-index-matched controls (n = 87), children with PWS (n = 29) had longer total sleep time (434 ± 72 vs. 365 ± 116 min; p < 0.01), higher sleep efficiency (86 ± 7 vs. 78 ± 15%; p < 0.05), and lower arousal events (8.1 ± 4.5 vs. 13.0 ± 8.9 events/h; p < 0.05). Mean oxygen saturation was lower in PWS children (94.3 ± 6.0 vs. 96.0 ± 2.0%; p < 0.05), with no other differences in respiratory parameters between groups. Eleven children with PWS (38%) met the criteria for further analyses of the impact of rhGH; polysomnography parameters did not change with treatment. Compared with other children undergoing polysomnography, children with PWS had more favorable markers of sleep continuity and lower oxygen saturation for the same level of respiratory disturbance. rhGH administration was not associated with changes in respiratory parameters in PWS.

Characterizing respiratory parameters, settings, and adherence in real-world patients using adaptive servo ventilation therapy: big data analysis.

There is minimal guidance around how to optimize inspiratory positive airway pressure (IPAP) levels during use of adaptive servo ventilation (ASV) in clinical practice. This real-world data analysis investigated the effects of IPAP and minimum pressure support settings on respiratory parameters and adherence in ASV-treated patients. A United States-based telemonitoring database was queried for patients starting ASV between August 1, 2014 and November 30, 2019. Patients meeting the following criteria were included: United States-based patients aged ≥ 18 years; AirCurve 10 device (ResMed); and ≥ 1 session with usage of ≥ 1 hour in the first 90 days. Key outcomes were mask leak and residual apnea-hypopnea index at different IPAP settings, adherence and therapy termination rates, and respiratory parameters at different minimum pressure support settings. There were 63,996 patients included. Higher IPAP was associated with increased residual apnea-hypopnea index and mask leak but did not impact device usage per session (average > 6 h/day at all IPAP settings; 6.7 h/day at 95th percentile IPAP 25 cm H2O). There were no clinically relevant differences in respiratory rate, minute ventilation, leak, and residual apnea-hypopnea index across all possible minimum pressure support settings. Patients with a higher 95th percentile IPAP or with minimum pressure support of 3 cm H2O were most likely to remain on ASV therapy at 1 year. Our findings showed robust levels of longer-term adherence to ASV therapy in a large group of real-world patients. There were no clinically important differences in respiratory parameters across a range of pressure and pressure support settings. Future work should focus on the different phenotypes of patients using ASV therapy. Malhotra A, Benjafield AV, Cistulli PA, etal. Characterizing respiratory parameters, settings, and adherence in real-world patients using adaptive servo ventilation therapy: big data analysis. J Clin Sleep Med. 2021;17(12):2355-2362.

Differences in Respiratory Parameters and RPE for Treadmill Speed and Slope

Differences in Respiratory Parameters and RPE for Treadmill Speed and Slope

Cardiorespiratory Response to Moderate Hypercapnia in Female College Students Expressing Behaviorally Inhibited Temperament.

Behaviorally inhibited (BI) temperament is marked by heightened behavioral sensitivity to environmental threats. The degree to which threat sensitivity is reflected in cardiorespiratory responses has been relatively unexplored. Female college students were exposed to modest hypercapnia (7.0% CO2) or ambient air (AA) while engaging in a computerized task with cued reinforcement features. All physiological variables except for blood pressure were processed in 4 min epochs corresponding to pre-exposure, exposure, and post-exposure. Primary respiratory measures were respiratory frequency (fb), tidal volume (VT), and minute ventilation (VE). Electrocardiograms (ECGs) were processed using ARTiiFACT software with resultant heart rate variability (HRV) measures in the frequency domain and time domain. Consistent with the literature, modest hypercapnia increased VT, Fb, and VE. No differences in respiratory parameters were detected between BI and non-behaviorally inhibited individuals (NI). For HRV in the time domain, RMSSD and NN50 values increased during CO2 inhalation which then returned to pre-exposure levels after CO2 cessation. Hypercapnia increased high frequency (HF) power which then recovered. BI exhibited reduced low frequency (LF) power during the pre-exposure period. For NI, LF power reduced over the subsequent phases ameliorating differences between BI and NI. Hypercapnia improved the task performance of BI. This is the largest study of female reactivity to hypercapnia and associated HRV to date. In general, hypercapnia increased time domain HRV and HF power, suggesting a strong vagal influence. Those expressing BI exhibited similar respiratory and HRV reactivity to NI despite inherently reduced LF power. Although 7% CO2 represents a mild challenge to the respiratory and cardiovascular systems, it is nonetheless sufficient to explore inherent difference in stress reactivity in those vulnerable to develop anxiety disorders.

Off-Target Effects of Clozapine-N-Oxide on the Chemosensory Reflex Are Masked by High Stress Levels.

Respiratory chemosensory circuits are implicated in several physiological and behavioral disorders ranging from sudden infant death syndrome to panic disorder. Thus, a comprehensive map of the chemosensory network would be of significant value. To delineate chemosensory neuronal populations, we have utilized pharmacogenetic Designer Receptors Exclusively Activated by Designer Drugs (DREADD) perturbations for acute neuronal perturbations in respiratory circuit mapping. Recent studies show that the biologically inert DREADD ligand clozapine-N-oxide (CNO) is back-metabolized into the bioactive compound clozapine in rodents, emphasizing the need for CNO-only DREADD-free controls, which have been carried out in several studies. However, we show that high CNO doses used in several chemosensory circuit mapping studies nonetheless affect the chemosensory ventilatory reflexes in control mice, which is unmasked by extensive habituation. Here, unhabituated control animals showed no differences in respiratory parameters after CNO administration, whereas habituated animals receiving the commonly used dose of 10 mg/kg of CNO show a deficit in the hypercapnic (high CO2) chemosensory reflex, which is not present in 1 mg/kg CNO treated or saline control groups. Our findings indicate that even in appropriately controlled studies, additional masked CNO off-target effects may exist and underscore the importance of using minimal doses of activating ligand in combination with high levels of habituation.

TRPM8 channel is involved in the ventilatory response to CO2 mediating hypercapnic Ca2+ responses

The role of TRP channels in the ventilatory response to CO2 was investigated in vivo. To this end, the respiration of unrestrained adult TRPM8-, TRPV1- and TRPV4-channel knockout mice was measured using whole-body plethysmography. Under control conditions and hyperoxic hypercapnia, no difference in respiratory parameters was observed between adult wild-type mice and TRPV1- and TRPV4-channel knockout mice. However, TRPM8-channel knockout mice showed decreased tidal volume under both hypercapnia and resting conditions. In addition, the expression of TRPM8, TRPV1 and TRPV4 mRNAs was detected in EGFP-positive glial cells in the medulla of GFAP promoter-EGFP transgenic mice by real-time PCR. Furthermore, we measured intracellular Ca2+ responses of TRPM8-overexpressing HEK-293 cells to hypercapnic acidosis. Subpopulations of cells that exhibited hypercapnic acidosis-induced Ca2+ response also responded to the application of menthol. These results suggest that TRPM8 partially mediates the ventilatory response to CO2 via changes in intracellular Ca2+ and is a chemosensing protein that may be involved in detecting endogenous CO2 production.

Association between age-related factors and extubation failure in elderly patients.

BackgroundElderly patients are being increasingly admitted to the intensive care unit (ICU) for mechanical ventilation. Previous studies demonstrated that 20% to 35% of elderly patients were reintubated within 48 to 72 hours after extubation. Given the age-related physiologic changes and multiple comorbidities in elderly patients, the current conventional parameters for predicting extubation outcomes may not be applicable to this population. This study was performed to identify the association between age-related parameters and extubation failure in elderly patients.MethodsIntubated elderly patients (age of ≥60 years) admitted to the medical ICU of a university-based hospital from October 2014 to July 2015 were included. Failed extubation was defined as reintubation within 48 hours after the first extubation. The associations of extubation failure with demographic data, vital signs, cognition and anxiety, and ventilator parameters at the time of intubation and extubation were analyzed.ResultsIn total, 127 intubated elderly patients were recruited. Extubation failure occurred in 15 patients (11.8%). Patients with failed extubation had a lower body temperature (37.0°C vs. 37.3°C, P < 0.05) but a higher Facial Anxiety Scale (FAS) score than those with successful extubation (3 vs. 2, P < 0.05). Patients with extubation failure had significantly higher levels of blood urea nitrogen (BUN) (39.88 vs. 58.47 g/dL), serum sodium (137.66 vs. 141.47 mmol/L), and serum calcium (9.52 vs. 10.0 g/dL) but a wider anion gap (12.23 vs. 9.97), but no significant differences in respiratory parameters were found between the two groups. Multiple logistic regression revealed no independent factors associated with successful extubation.ConclusionThis study revealed no strong predictive factors. However, several physiological parameters (lower body temperature and higher FAS scores) and metabolic parameters (BUN, sodium, calcium, and anion gap) were significantly associated with the rate of extubation failure.

Influence of Home Based Exercise Intensity on the Aerobic Capacity and 1 Year Re-Hospitalization Rate in Patients with Chronic Heart Failure

Purpose: This study investigated the effects of home-based exercise intensity on the aerobic capacity and 1 year re-hospitalization rate in patients with chronic heart failure (CHF). Methods: Forty seven patients with CHF (males 33, females 14, age 61.3±9.8 years) participated in this study. The patients were allocated randomly to 3 groups in accordance with home-based exercise intensity: no home based exercise (NHE, 40%, n=19), moderate intensity home-based exercise (MIHE, 43%, n=20), and high intensity home based exercise (HIHE, 17%, n=8). All patients completed the symptom-limited cardiopulmonary exercise (CPX) test safely at the cardiac rehabilitation hospital. Results: The NHE group significantly showed lower peak VO2 and a higher VE/VCO2 slope than the MIHE (p<0.05) and HIHE (p<0.01) groups. On the other hand, the NHE group did not show significant differences in the other hemodynamic responses, such as heart rate (HR) max, HR reserve, maximal systolic blood pressure (SBP), and SBP reserve. Nine out of 19 NHE patients (47%) were re-hospitalized related to heart disease and two out of 20 MIHE (10%) patients were re-hospitalized, but nobody in the HIHE group were re-hospitalized within 1 year from the CPX test. Conclusion: In patients with CHF, home-based self-exercise is one of the important factors for reducing the re-hospitalization rate. In addition, improved aerobic capacity is strongly associated with a lower re-hospitalization rate. In particular, re-hospitalized CHF patients showed significant differences in respiratory parameters and hemodynamic parameters compared to the non-re-hospitalized patients.

Outcomes in Patients With Acute Stroke Requiring Mechanical Ventilation: Predictors of Mortality and Successful Extubation

BackgroundThe majority of patients with acute stroke requiring mechanical ventilation have a poor prognosis and often present difficult decisions regarding extubation. The best criteria for planned extubation in these patients are uncertain. MethodsWe reviewed the electronic medical records of patients hospitalized between 1/1/2010 and 12/15/2015 with acute stroke requiring mechanical ventilation to determine the mortality rate, the respiratory parameters recorded before planned extubation, and the reintubation rate. ResultsThis study included 226 patients. The mean age was 60.3 ± 14.3 years. The mean duration of mechanical ventilation was 6.5 ± 5.9 days. The overall in-hospital mortality rate was 56.6%. The best predictors of mortality were age and stroke volume calculated from radiographic images. One hundred and one patients had planned extubations; 9 patients (8.9%) required reintubation. There was no difference in respiratory parameters or Glasgow coma scale scores between those patients with successful extubation and those patients with failed extubation. ConclusionsThe in-hospital mortality rate of patients with acute stroke who require mechanical ventilation is quite high. The success rate with planned extubation is relatively good and comparable to rates in previous studies which largely involved patients with respiratory failure. There is no single weaning parameter or Glasgow coma scale score which identifies patients with high success rates.

Heterogeneous pattern of differences in respiratory parameters between elderly with either good or poor FEV1

BackgroundThe relationship of spirometric values to other respiratory and functional parameters in advanced age is not well studied. We assessed this relationship in elderly subjects with either good or poor spirometric parameters to reveal whether different domains of lung function show comparable differences between the two groups.MethodsAmong subjects of the population-based KORA-Age cohort (n = 935, 65-90y; 51% male) two groups were selected from either the lower (LED; n = 51) or the upper (UED; n = 72) end of the FEV1 distribution. All subjects did not have a history of lung disease and were non-smokers at the time of the study. Measurements included spirometry, body plethysmography, diffusing capacity for NO and CO, respiratory pump function and exhaled NO (FeNO). In addition, 6-min walking distance as a functional overall measure, as well as telomere length of blood leukocytes and serum 8-hydroxydeoxyguanosine (8-OHdG) as potential markers of overall biological ageing and stress were determined.ResultsIn the majority of parameters, LED subjects showed significantly impaired values compared to UED subjects. Differences in spirometric parameters, airway resistance and respiratory pump function ranged between 10% and more than 90% in terms of predicted values. In contrast, volume-related CO and NO diffusing capacity showed differences between groups of lower than 5%, while telomere length, 8-OHdG and FeNO were similar. This was reflected in the differences in “functional age” as derived from prediction equations.ConclusionsIn elderly subjects without a history of lung disease differences in spirometric parameters were associated with differences in other lung-mechanical parameters including body plethysmography but not with differences in volume-corrected gas exchange measures. Thus, the concept of a general “lung age” as suggested by the widespread use of this term in connection with spirometry should be considered with caution.

Pediatric Home Sleep Apnea Testing: Slowly Getting There!

Pediatric OSA can result in significant neurocognitive, behavioral, cardiovascular, and metabolic morbidities. Prompt diagnosis and treatment are, therefore, of paramount importance. The current gold standard for diagnosis of OSA in children is in-laboratory polysomnography (PSG). Home sleep apnea testing has been considered as an alternative as it is potentially more cost effective, convenient, and accessible. This review concentrates mainly on the use of type 2 and 3 portable monitoring devices. The current evidence on the feasibility and diagnostic accuracy of home testing in the diagnosis of pediatric OSA was examined. Overall, the evidence in children is limited. Feasibility studies that have been performed have on the whole shown good results, with several reporting > 90% of their home recordings as meeting predetermined quality criteria regarding signal artifact and minimum recording time. The limited data comparing type 2 studies with in-laboratory PSG have shown no significant differences in respiratory parameters. The results pertaining to diagnostic accuracy of type 3 home sleep apnea testing devices are conflicting. Although more research is needed, home testing with at least a type 3 portable monitor offers a viable alternative in the diagnosis of otherwise healthy children with moderate to severe OSA, particularly in settings where access to polysomnography is scarce or unavailable. Of note, since most studies have been performed in habitually snoring healthy children, home sleep apnea testing may not be applicable to children with other comorbid conditions. In particular, CO2 monitoring is important in children in whom there is concern regarding nocturnal hypoventilation, such as children with neuromuscular disease, underlying lung disease, or obesity hypoventilation, and most home testing devices do not include a transcutaneous or end-tidal CO2 channel.

Effects of rocuronium on gastric insufflation related to facemask ventilation in general anaesthesia patients

To explore the effect of rocuronium on gastric insufflation related to facemask ventilation in general anaesthesia patients. Eighty patients from June to October 2015 undergoing elective operation under general anaesthesia at Ningbo NO.2 Hospital , ASA I or II grade, aged 18-65, were enrolled in this study and divided into two groups (n=40): Group R (rocuronium) and Group C (for control). Facemask pressure-controlled ventilation was started after general anaesthesia induced with propofol and remifentanil for a 2 min period while gastric insufflation was detected by ultrasonography of the antrum. The cross-sectional antral area (CSA) was measured using ultrasonography before and after facemask ventilation. Respiratory parameters were also recorded. Compared to the antral area before FMV, the CSA significantly increased in group R and C after FMV [post-FMV:(579.5 ± 167.3), (508.1 ± 112.2)mm²; pre-FMV(479.4 ± 110.2), (451.2 ± 103.4) mm²; t=5.938, 4.302, P<0.001]. All the patients were divided into four subgroups according to the gastric insufflation (R+, R-, C +, C-) and there were significant increases in the values of CSA before and after FMV in groups R+ and C+[post-FMV(647.7 ± 150.6), (546.2 ± 121.1) mm²; pre-FMV (501.2 ± 113.6), (422.6 ± 101.5) mm²; t=7.885, 8.719, P<0.001], without any significant increase in groups R- and C-[post-FMV(496.0 ± 150.9), (489.8 ± 105.1) mm²; pre-FMV (452.9 ± 102.8), (465.0 ± 103.3) mm²; t=1.793, 1.663, P>0.05]. Compared with the group R- , the CSA of group R+ significantly increased before and after FMV[group R+ (146.6 ± 87.2) mm²; group R- (43.1 ± 102.1) mm²; t=3.458, P<0.001]; compared with the group C- , the CSA of group C+ significantly increased before and after FMV [group C+ (123.6 ± 51.1) mm²; group C- (24.8 ± 77.4) mm²; t=4.172, P<0.001]; there was no significant difference between the difference value of CSA in groups R+ and C+ before and after FMV (t=0.983, P>0.05). The incidence of gastric insufflation was 55% and 32.5% in group R and C, respectively (χ² =4.114, P<0.05). There was no significant difference in respiratory parameters between group R and C. The study suggests that rocuronium may promote gastric insufflation related to facemask ventilation (15 cmH₂O PCV)in general anaesthesia patients.

Sleep alterations in children with refractory epileptic encephalopathies: A polysomnographic study

Data on the relationship between sleep disturbances and refractory epileptic encephalopathies (EEs) are scarce. Our aim was to assess, by means of nocturnal polysomnography, if children with EEs present with objective alterations in sleep organization. Twenty-three children with EEs (12 males; mean age: 8.7±1.4years) and 40 healthy controls (22 males; mean age: 8.8±1.1years) underwent an overnight full polysomnography (PSG). Relative to controls, children with EEs showed a significant reduction in all PSG parameters related to sleep duration time in bed (TIB-min p<0.001), total sleep time (TST-min p<0.001), and sleep percentage (SPT-min p<0.001), as well as significantly higher REM latency (FRL-min p<0.001), rate in stage shifting (p=0.005), and number of awakenings/hour (p=0.002).Relative to controls, children with EEs also showed significant differences in respiratory parameters (AHI/h p<0.001, ODI/h p<0.001, SpO2% p<0.001, SpO2 nadir% p<0.001) and a higher rate of periodic limb movements (PLMs% p<0.001). Our findings suggest that sleep evaluation could be considered mandatory in children with refractory epileptic encephalopathy in order to improve the clinical management and the therapeutic strategies.

Is leg compression beneficial for alpine skiers?

BackgroundThis study examined the effects of different levels of compression (0, 20 and 40 mmHg) produced by leg garments on selected psycho-physiological measures of performance while exposed to passive vibration (60 Hz, amplitude 4-6 mm) and performing 3-min of alpine skiing tuck position.MethodsPrior to, during and following the experiment the electromygraphic (EMG) activity of different muscles, cardio-respiratory data, changes in total hemoglobin, tissue oxygenation and oscillatory movement of m. vastus lateralis, blood lactate and perceptual data of 12 highly trained alpine skiers were recorded. Maximal isometric knee extension and flexion strength, balance, and jumping performance were assessed before and after the experiment.ResultsThe knee angle (−10°) and oscillatory movement (−20-25.5%) were lower with compression (P < 0.05 in all cases). The EMG activities of the tibialis anterior (20.2-28.9%), gastrocnemius medialis (4.9-15.1%), rectus femoris (9.6-23.5%), and vastus medialis (13.1-13.7%) muscles were all elevated by compression (P < 0.05 in all cases). Total hemoglobin was maintained during the 3-min period of simulated skiing with 20 or 40 mmHg compression, but the tissue saturation index was lower (P < 0.05) than with no compression. No differences in respiratory parameters, heart rate or blood lactate concentration were observed with or maximal isometric knee extension and flexion strength, balance, and jumping performance following simulated skiing for 3 min in the downhill tuck position were the same as in the absence of compression.ConclusionsThese findings demonstrate that with leg compression, alpine skiers could maintain a deeper tuck position with less perceived exertion and greater deoxygenation of the vastus lateralis muscle, with no differences in whole-body oxygen consumption or blood lactate concentration. These changes occurred without compromising maximal leg strength, jumping performance or balance. Accordingly, our results indicate that the use of lower leg compression in the range of 20-40 mmHg may improve alpine skiing performance by allowing a deeper tuck position and lowering perceived exertion.

A comparison of inspiratory airflow dynamics during sleep between upper airway resistance syndrome patients and healthy controls

A test of the hypothesis that upper airway resistance syndrome (UARS) patients have an increased prevalence of inspiratory airflow limitation (IFL) during sleep compared to healthy controls. We compared inspiratory airflow dynamics during sleep between 12 UARS patients (nine females and three males) and 12 healthy controls matched for age, gender and obesity with maximal age limited at 45years. A standard clinical polysomnogram (airflow measured with a nasal/oral pressure catheter) was performed to assess the impact of SDB on the participants' natural sleep. A second full-night polysomnogram with a pneumotachograph and a supraglottic pressure catheter to measure airflow and effort was performed to compare the maximal inspiratory airflow and effort and the percentage of flow-limited breaths during supine, continuous stage 2 sleep between groups. During clinical polysomnography, UARS participants did not differ significantly from controls in sleep architecture or fragmentation. We observed a small difference in apnea hypopnea index between UARS participants and controls (1.6 ± 1.9 vs. 0.4 ± 0.3, respectively; p = 0.035). During supine, continuous stage 2 sleep, 64.2% (35.8; mean (SD)) of UARS participants' breaths were flow-limited compared with 34.0% (39.3) of controls' breaths (p = 0.06). The groups did not differ in maximal inspiratory airflow or inspiratory effort. Our findings indicate a less-than-robust difference in respiratory parameters during sleep between UARS patients and healthy controls and no difference in standard sleep parameters or sleep fragmentation. We consider a pathophysiology of UARS that incorporates these findings.

Brain mitochondrial function in a murine model of cerebral malaria and the therapeutic effects of rhEPO

Cerebral malaria (CM) is a life-threatening complication of Plasmodium falciparum infection. The pathogenesis of CM is complex. Cerebral metabolic dysfunction is implicated in CM, which may be caused by both an impaired cerebral microcirculation and a dysregulated inflammatory response affecting cellular respiration of mitochondria. Recombinant human erythropoietin (rhEPO) is a promising new therapy that has been shown to reduce mortality in a mouse model of CM. In order to further elucidate the metabolic dysfunction in CM the objective of the present study was to assess brain mitochondrial respiratory function in CM with and without rhEPO treatment. The P. berghei ANKA – C57BL/6 murine model of CM was used. Mitochondrial respiration was analyzed in brain homogenates using high-resolution respirometry and a multiple substrate and inhibitor protocol. The animals were divided into four groups; infected injected with saline or with rhEPO, non-infected injected with saline or with rhEPO. Infected mice developed CM and treatment with rhEPO attenuated clinical signs of disease. There were no differences in respiratory parameters of brain mitochondria between infected and non-infected mice and no connection between disease severity and mitochondrial respiratory function. Treatment with rhEPO similarly had no effect on respiratory function. Thus cerebral metabolic dysfunction in CM does not seem to be directly linked to altered mitochondrial respiratory capacity as analyzed in brain homogenates ex vivo.This article is part of a Directed Issue entitled: Bioenergetic dysfunction, adaptation and therapy.