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Expiratory Flow Rate (expiratory + flow_rate)
Kinds of Expiratory Flow Rate Selected AbstractsValidation of the Pulmonary Score: An Asthma Severity Score for ChildrenACADEMIC EMERGENCY MEDICINE, Issue 2 2002Sharon R. Smith MD Objectives: In the absence of a validated "user-friendly" method of scoring asthma severity, the authors derived the pulmonary score (PS). The purpose of this study was to begin validation trials of the PS by comparing it with the peak expiratory flow rate (PEFR). Methods: The study enrolled a convenience sample of children, aged 5-17 years, who came to the emergency department (ED) for treatment of an acute asthma exacerbation. The PEFR (best of three attempts) and the PS were measured before and after the first albuterol treatment by a physician and a nurse from a pool of 45 trained observers. The PS includes respiratory rate, wheezing, and retractions, each rated on a 0-3 scale. Decreasing PS and increasing PEFR indicate clinical improvement. Pre- and post-treatment PEFRs and PSs were compared using paired t-tests to establish construct validity. Correlation of pre- and post-treatment PSs with PEFRs was measured to establish criterion validity. Results: Forty-six subjects completed the study. Mean percent predicted PEFR improved after treatment by 20.7% (p = 0.0001), and mean PS by 1.5 for nursing-obtained scores (p < 0.0001) and 1.9 for physician-obtained scores (p < 0.0001). Pre- and post-treatment PSs were significantly correlated with PEFRs. Correlations for the nursing-obtained scores were pre-treatment r = -0.57 (p = 0.0003) and post-treatment r = -0.67 (p = 0.0001), and for the physician-obtained scores were pre-treatment r = -0.44 (p = 0.003) and post-treatment r = -0.56 (p = 0.0001). The pre-treatment interrater reliability was 0.62 and the post-treatment was 0.53. Conclusions: These data support the construct and criterion validities of the PS as a measure of asthma severity among children in the ED. The PS is a practical substitute to estimate airway obstruction in children who are too young or too sick to obtain PEFRs. [source] A clinical pharmacological study of the potential beneficial effects of a propolis food product as an adjuvant in asthmatic patientsFUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 1 2003M. T. Khayyal Abstract The aqueous extract of propolis has been formulated as a nutritional food product and administered, as an adjuvant to therapy, to patients with mild to moderate asthma daily for 2 months in the framework of a comparative clinical study in parallel with a placebo preparation. The diagnosis of asthma was made according to the criteria of patient classification of the National Institutes of Health and Global Initiative for Asthma Management. At inclusion, the pulmonary forced expiratory volume in the first second (FEV1) as a percentage of the forced vital capacity (FVC) was more than 80% in mild persistent cases, and between 60 and 80% in moderate persistent cases, showing an increase in the degree of reversibility of >,15% in FEV1. All patients were on oral theophylline as controller therapy, none was receiving oral or inhaled corticosteroids, none had other comorbidities necessitating medical treatment, and all were from a middle-class community and had suffered from asthma for the last 2,5 years. Twenty-four patients received the placebo, with one drop-out during the study, while 22 received the propolis extract, with no drop-outs. The age range of the patients was 19,52 years; 36 were male and 10 female. The number of nocturnal attacks was recorded on a weekly basis, while pulmonary function tests were performed on all patients at the beginning of the trial, 1 month later and at the termination of the trial. Immunological parameters, including various cytokines and eicosanoids known to play a role in asthma, were measured in all patients at the beginning of the trial and 2 months later. Analysis of the results at the end of the clinical study revealed that patients receiving propolis showed a marked reduction in the incidence and severity of nocturnal attacks and improvement of ventilatory functions. The number of nocturnal attacks dropped from an average of 2.5 attacks per week to only 1. The improvement in pulmonary functions was manifested as a nearly 19% increase in FVC, a 29.5% increase in FEV1, a 30% increase in peak expiratory flow rate (PEFR), and a 41% increase in the forced expiratory flow rate between 25 and 75% of the vital capacity (FEF25-75). The clinical improvement was associated with decreases by 52, 65, 44 and 30%, respectively, of initial values for the pro-inflammatory cytokines tumor necrosis factor (TNF)-,, ICAM-1, interleukin (IL)-6 and IL-8, and a 3-fold increase in the ,protective' cytokine IL-10. The levels of prostaglandins E2 and F2, and leukotriene D4 were decreased significantly to 36, 39, and 28%, respectively, of initial values. Patients on the placebo preparation showed no significant improvement in ventilatory functions or in the levels of mediators. The findings suggest that the aqueous propolis extract tested is potentially effective as an adjuvant to therapy in asthmatic patients. The benefits may be related to the presence in the extract of caffeic acid derivatives and other active constituents. [source] The effects of exposure to environmental tobacco smoke on pulmonary function in children undergoing anesthesia for minor surgeryPEDIATRIC ANESTHESIA, Issue 5 2006JAMES M. O'ROURKE FFARCSI Summary Background:, The objectives of this study were to assess whether children exposed to environmental tobacco smoke (ETS) present for surgery with poorer pulmonary function, and experience a more pronounced deterioration in pulmonary function following anesthesia and surgery, than non-ETS-exposed children. Methods:, Fifty-four children aged 5,15 years with a history of ETS exposure from one or both parents and 54 children with no such ETS history were included in the study. All participants were presenting for ambulatory surgery and were judged to conform to American Society of Anesthesiology class I or II. Spirometry was performed preoperatively, postoperatively in the recovery ward when the child met criteria for discharge (Aldrete score 8), and before discharge from the day ward. Results:, The ETS-exposed group had a significantly lower mean preoperative peak expiratory flow rate (PEFR) (9.5 points lower percent predicted, 95% confidence interval ,18.1 to ,1.0, P = 0.03). Although not statistically significant, they also had lower percent predicted baseline mean values of the other spirometric variables that were measured (forced expiratory volume in 1 s ,4.5%, P = 0.07; forced vital capacity ,4.1%, P = 0.10; forced expiratory flow between 25% and 75%,3.6%, P = 0.44). Pulmonary function tests (PFTs) performed in recovery were between 8% and 14% worse than preoperative values, but the results were similar in the two groups of children. PFTs performed before hospital discharge demonstrated an near-complete recovery to baseline values. Again the pattern was similar in exposed and nonexposed children. Conclusions:, Environmental tobacco smoke exposure is associated with lower preoperative PEFR values, but does not impact on recovery from anesthesia for healthy children undergoing ambulatory anesthesia. [source] Acute symptoms associated with asphalt fume exposure among road pavers,AMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 9 2006Allison L. Tepper PhD Background Although asphalt fume is a recognized irritant, previous studies of acute symptoms during asphalt paving have produced inconsistent results. Between 1994 and 1997, the National Institute for Occupational Safety and Health (NIOSH) evaluated workers at seven sites in six states. Methods NIOSH (a) measured exposures of asphalt paving workers to total (TP) and benzene-soluble particulate (BSP), polycyclic aromatic compounds, and other substances; (b) administered symptom questionnaires pre-shift, every 2 hr during the shift, and post-shift to asphalt exposed and nonexposed workers; and (c) measured peak expiratory flow rate (PEFR) of asphalt paving workers when they completed a symptom questionnaire. Results Full-shift time-weighted average exposures to TP and BSP ranged from 0.01 to 1.30 mg/m3 and 0.01 to 0.82 mg/m3, respectively. Most BSP concentrations were <0.50 mg/m3. Asphalt workers had a higher occurrence rate of throat irritation than nonexposed workers [13% vs. 4%, odds ratio (OR),=,4.0, 95% confidence interval (CI): 1.2,13]. TP, as a continuous variable, was associated with eye (OR,=,1.34, 95% CI: 1.12,1.60) and throat (OR,=,1.40, 95% CI: 1.06,1.85) symptoms. With TP dichotomous at 0.5 mg/m3, the ORs and 95% CIs for eye and throat symptoms were 7.5 (1.1,50) and 15 (2.3,103), respectively. BSP, dichotomous at 0.3 mg/m3, was associated with irritant (eye, nose, or throat) symptoms (OR,=,11, 95% CI: 1.5,84). One worker, a smoker, had PEFR-defined bronchial lability, which did not coincide with respiratory symptoms. Conclusions Irritant symptoms were associated with TP and BSP concentrations at or below 0.5 mg/m3. Am. J. Ind. Med. 49:728,739, 2006. © 2006 Wiley-Liss, Inc. [source] Factors associated with health-related quality of life among low-compliant asthmatic adults in Korea,RESEARCH IN NURSING & HEALTH, Issue 2 2009Ja Yun Choi Abstract This cross-sectional descriptive study was conducted to identify the factors associated with health-related quality of life (HRQoL) in low-compliant Korean adults with asthma. The sample consisted of 178 patients referred by a physician to the education clinic at a University hospital in Korea. Stepwise multiple regression analysis revealed that previous hospital admissions, recent asthma-related symptoms within the previous week, lower peak expiratory flow rate, and lower level of asthma knowledge were independently associated with lower HRQoL and accounted for 46% of the total variance. Health care providers should focus on these factors to increase perceptions of HRQoL among low-compliant patients. Interventional strategies need to be developed to emphasize the importance of compliance to the self-monitoring regimen and management protocols. © 2008 Wiley Periodicals, Inc. Res Nurs Health 32:140,147, 2009 [source] Intravenous magnesium sulfate in acute severe asthmaRESPIROLOGY, Issue 3 2000Chaichan Boonyavorakul Objective: Intravenous magnesium sulfate (MgSO4), as an adjunctive medication to the standard treatment of acute asthma, improves admission rate or severity score in acute severe asthma patients. Methodology: We conducted a randomized double-blind placebo controlled trial with subjects from the emergency room, Ramathibodi Hospital, Bangkok, Thailand. Patients, aged 15,65 years with acute severe asthma attack, whose severity scores were greater than 4 and who were willing to be enrolled in a study during March to November 1997 participated in the study. Randomly allocated patients received either 2 g intravenous MgSO4 or placebo, sterile water, as an adjunctive medication to standard therapy for acute asthma. The medication was diluted in 50 mL of 0.9% normal saline. Measurement: Severity scores were measured by two investigators using Fischl's indices. The times interval of measurements were at the initial (0), 60, 120, 180, and 240 min from receipt of treatment. Patients were hospitalized if the severity scores at 240 min exceeded 1. Risk ratio (RR) and 95% confidence interval (CI) of RR were applied to estimate the risk of admission. Analysis of variance with repeated measurement on time was used to determine the severity score between two groups. Results: Thirty-four patients with acute severe asthma were enrolled in the present study. One patient from the placebo group was excluded because he did not consent to undergoing peak expiratory flow rate. Seventeen patients received MgSO4 and 16 patients received placebo. The general characteristics between the two groups were not significantly different, which reflected the quality of randomization. The admission rates of the placebo and MgSO4 group were 25.00% and 17.65%, respectively. Patients who received MgSO4 had preventive risk to be hospitalized 0.71 times relative to patients who received placebo. However, this preventive risk did not reach statistical significance (95% CI of RR = 0.19,2.67). The severity score at any time between the two groups was also not statistically significantly different (P = 0.366). Conclusion: With the present evidence, the hypothesis was not confirmed. Magnesium sulphate as an adjunct to standard therapy did not improve either admission rate or severity score in patients with acute severe asthma. [source] Subclinical pulmonary dysfunction in spinocerebellar ataxias 1, 2 and 3ACTA NEUROLOGICA SCANDINAVICA, Issue 5 2010S. J. Sriranjini Sriranjini SJ, Pal PK, Krishna N, Sathyaprabha TN. Subclinical pulmonary dysfunction in spinocerebellar ataxias 1, 2 and 3. Acta Neurol Scand: 2010: 122: 323,328. © 2009 The Authors Journal compilation © 2009 Blackwell Munksgaard. Objectives,,, Evaluation of pulmonary function in patients with spinocerebellar ataxias (SCA) 1, 2 and 3 without clinical evidence of pulmonary dysfunction. Methods,,, Thirty patients (F:M = 7:23; age: 35 ± 11.3 years; SCA1 , 13, SCA2 , 9 and SCA3 , 8) without clinical manifestations of respiratory dysfunction and 30 controls underwent pulmonary function tests. The percentage predicted values of forced vital capacity (FVC), volume of air exhaled during first second of FVC (FEV1), peak expiratory flow rate (PEFR) and maximal voluntary ventilation (MVV), actual values of maximal inspiratory and expiratory pressures (MIP and MEP in mmHg), and ratios of actual values of FEV1/FVC (%) and FEV1/PEFR (ml/l/min) were analyzed. Results,,, Compared with controls SCA patients had significant reductions of FVC (71.1 ± 17.5 vs 85.5 ± 18.7; P < 0.01), PEFR (51.5 ± 20.7 vs 77.1 ± 24.9; P < 0.001), MVV (64.4 ± 21.6 vs 97.2 ± 22.7; P < 0.001), MIP (27.7 ± 16.8 vs 50.1 ± 15.1; P < 0.001) and MEP (38.1 ± 18.7 vs 74.7 ± 16.0; P < 0.001), elevation of FEV1/PEFR (10.5 ± 2.8 vs 7.4 ± 2.1; P < 0.001), but no significant change of FEV1 and FEV1/FVC. FEV1/PEFR correlated positively with illness duration and MVV negatively with severity of illness. Conclusions,,, The present study showed subclinical restrictive type of pulmonary dysfunction in SCA, and possible presence of upper airway obstruction. Chest physiotherapy and breathing exercises should be introduced early in management of SCA. [source] Pulmonary function tests and diaphragmatic compound muscle action potential in patients with sporadic amyotrophic lateral sclerosisACTA NEUROLOGICA SCANDINAVICA, Issue 6 2010T. N. Sathyaprabha Sathyaprabha TN, Pradhan C, Nalini A, Thennarasu K, Raju TR. Pulmonary function tests and diaphragmatic compound muscle action potential in patients with sporadic amyotrophic lateral sclerosis. Acta Neurol Scand: 2010: 121: 400,405. © 2010 The Authors Journal compilation © 2010 Blackwell Munksgaard. Background,,, Respiratory failure is the primary cause of death in patients with amyotrophic lateral sclerosis (ALS). Diaphragmatic compound muscle action potentials (DCMAP) are valid parameters to assess the respiratory muscle innervation. Aim,,, In this study we propose to establish evidence of pulmonary dysfunction in patients with ALS and its relation to DCMAP parameters among patients with sporadic ALS. Materials and methods,,, Twenty nine patients (M-20, F-9) diagnosed to have sporadic ALS by El. Escorial criteria, without symptoms of pulmonary dysfunction, and able to perform the PFT satisfactorily, were studied. Thirty controls (M-20, F-10) were selected from patient's relatives. Forced vital capacity (FVC), forced expiratory volume in one second (FEV1), peak expiratory flow rate (PEFR) and maximum voluntary ventilation (MVV) were measured by spirometry. Maximum expiratory pressure (MEP) was measured by digital peak pressure monitor. Right phrenic nerve conductions (DCMAP) were performed and the latencies and amplitude of diaphragmatic com-pound action potential (DCMAP) was recorded in controls and ALS patients. Results,,, The mean age of patients was 51.41 ± 10.72 years (37,82) and control was 53.57 ± 8.85 years (30,68). None of the patients had symptoms or clinical evidence of respiratory dysfunction. The FVC, FEV1, PEFR, MVV, MIP and MEP were significantly (P < 0.001) reduced in ALS. The mean DCMAP amplitude was reduced among patients (610 ± 506.231 ,v) as compared to controls (1303.33 ± 584.56, P < 0.001) and mean latency was increased in patients (9.73 ± 2.57 ms) compared to controls (7.69 ± 0.87, P = 0.001). There was significant negative correlation between PFTs and latencies of DCMAP. Amplitude of DCMAP did not correlate with PFTs. Conclusion,,, There is significant negative correlation between DCMAP latencies and PFTs suggesting early loss of myelinated fibres and diaphragmatic dysfunction. DCMAP latencies may be a good indicator of early respiratory muscle involvement and also of disease progression in ALS. [source] End-tidal Carbon Dioxide Measurements in Children with Acute AsthmaACADEMIC EMERGENCY MEDICINE, Issue 12 2007Bridgette D. Guthrie MD Objectives A noninvasive method to assess ventilation may aid in management of children with acute asthma. The purpose of this study was to evaluate the association between end-tidal carbon dioxide (EtCO2) values and disease severity among children with acute asthma. Methods This was a prospective, blinded, observational study of children 3,17 years old treated for acute asthma in a pediatric emergency department (ED). EtCO2 measurements were taken before the initiation of therapy and after each nebulization treatment (maximum of three). Peak expiratory flow rate (PEFR), Pediatric Asthma Severity Score (PASS), oxygen saturation, and disposition were recorded. Treating physicians, unaware of the EtCO2 results, made all treatment decisions, including disposition. Results One hundred children were enrolled. The mean initial EtCO2 value was 35 mm Hg (95% confidence interval = 34.3 to 36.1 mm Hg). The mean disposition EtCO2 value was 33.3 mm Hg (95% confidence interval = 32.6 to 34.4 mm Hg). PEFR measures were completed on 43 patients and PASS recorded on 100 patients. There was an overall trend toward lower EtCO2 values during treatment (p < 0.01). Sixteen patients were admitted. Initial EtCO2 values were lower among children admitted to the hospital (35.6 mm Hg vs. 32.9 mm Hg; Mann-Whitney U test; p < 0.02). EtCO2 values at disposition did not differ between groups based on PEFR, PASS, or hospital admission. Conclusions Noninvasive bedside measurement of EtCO2 values among children with acute asthma is feasible. EtCO2 values did not distinguish children with mild disease from those with more severe disease. Further data are needed to clarify the association between EtCO2 values and other indicators of disease severity, particularly in children with more severe disease. [source] Relationship between changes in interferon-, production by peripheral blood T cells and changes in peak expiratory flow rate in patients with chronic stable asthmaCLINICAL & EXPERIMENTAL ALLERGY, Issue 12 2002Y. I. Koh Summary Background Cytokines production by T helper lymphocytes (Th cells), which orchestrate the interplay of the different cells involved in airway inflammation of asthma, may be reflected in peripheral blood. Some studies have suggested that the Th cell cytokines by peripheral blood T cells correlate with asthma severity. Objective To investigate the relationship between changes in IFN-, production by peripheral blood T cells and changes in lung function in chronic stable asthmatics. Methods Sixteen patients with chronic stable moderate asthma aged 35,65 years (nine women) were recruited. Morning and evening peak expiratory flow rates (PEFR) monitoring and blood sampling for peripheral blood T cell culture, total IgE and blood eosinophils were performed at baseline and week 12. Levels of IFN-,, IL-4 and IL-5 in culture supernatants of peripheral blood T cell were determined by using enzyme-linked immunosorbent assay (ELISA) kits. Results Patients with increased IFN-, changes from baseline showed significantly increased changes in morning (P = 0.02) and evening (P < 0.05) PEFR compared with those with decreased IFN-, changes. The changes in IFN-, production and IFN-,: IL-4 ratio significantly correlated with the changes in morning PEFR (Rs = 0.59, P < 0.02; Rs = 0.63, P < 0.01, respectively) and tended to correlate with the changes in evening PEFR (Rs = 0.45, P = 0.08; Rs = 0.5, P = 0.05, respectively). The changes in IL-4 and IL-5 did not correlate with the changes in IgE and blood eosinophils, respectively. Conclusions These findings suggest that IFN-, may be associated with the alteration of lung function in asthmatics and play a role in the pathophysiology of chronic stable asthma. [source] Validation of the Clinical COPD Questionnaire as a psychophysical outcome measure in adult laryngotracheal stenosisCLINICAL OTOLARYNGOLOGY, Issue 4 2009S.A.R. Nouraei Objectives:, To validate the Clinical Chronic Obstructive Pulmonary Disease Questionnaire (CCQ), a patient-administered instrument developed for bronchopulmonary disease as a disease-specific psychophysical outcome measure for adult laryngotracheal stenosis. Design:, Prospective observational study. Settings:, Tertiary/National referral airway reconstruction centre. Participants:, Thirty-three tracheostomy-free patients undergoing endoscopic laryngotracheoplasty. Main outcome measures:, CCQ and the Medical Research Council (MRC) Dyspnoea scale, a previously validated but more limited scale, were administered to patients 2 weeks before surgery, preoperatively, and 2 weeks after endoscopic laryngotracheoplasty. Pulmonary function was assessed preoperatively. Internal consistency was assessed with Cronbach , statistics and test,retest reliability was determined using intraclass correlation. Correlations between CCQ and MRC scale, and pulmonary function were used to assess convergent and divergent validity respectively. Instrument responsiveness was assessed by correlating total and domain-specific CCQ scores with anatomical disease severity and post-treatment effect size. Results:, There were 12 males and 21 females. Mean age was 44 ± 15 years. Cronbach , coefficient and intraclass correlation coefficient were 0.88 and 0.95 respectively. Total and domain-specific CCQ scores significantly correlated with the MRC scores (P < 0.001) and significant correlations between CCQ and peak expiratory flow rate and FEV1 were identified (P < 0.03). There were statistically significant changes in total and domain-specific CCQ scores when different stenosis severities were compared. Clinical COPD Questionnaire scores also changed significantly and congruently following surgery (P < 0.05 in both cases). Discussion:, Clinical COPD Questionnaire is a valid and sensitive instrument for assessing symptom severity and levels of function and well-being in adult patients with laryngotracheal stenosis and can be used as a patient-centred disease-specific outcome measure for this condition. [source] Symptom Perception and Adherence to Asthma Controller MedicationsJOURNAL OF NURSING SCHOLARSHIP, Issue 3 2006Ruth Ohm Purpose: To explore asthma symptom perception and the relationship between asthma symptom perception and adherence to asthma treatment. Design: Adult patients (N=120) of asthma/allergy specialty clinics, taking Advair® as a controller medication, were enrolled in this cross-sectional descriptive study. Methods: Ninety-seven participants completed 4 weeks of daily diaries to assess subjective symptom perception and measured peak expiratory flow rates (PEFR), both done twice daily. Individual perceptual accuracy scores (PAS) were determined by correlating the subjective symptom perception scores with the PEFRs. Measures included demographic variables, illness identity (personal control and treatment control, consequences, and timeline-cyclical subscales of the IPQ-R), asthma severity (FEV1 percentage) and a single-item indicator of perceived asthma severity. Adherence was measured by the Medication Adherence Report Scale (MARS) and by an Advair® dose count (percentage of doses taken as prescribed). Findings: Independent t tests comparing adherence rates of good versus poor perceivers were not significant, using either the percentage Advair® dose count or the MARS. Multiple regression analyses showed that years with asthma, illness identity, and peak flow variability were all significant explanatory variables for perceptual accuracy. Conclusion: Peak flow variability adds complexity to the relationship between perceptual accuracy and adherence that warrants further investigation. [source] Comparison of perioperative spirometric data following spinal or general anaesthesia in normal-weight and overweight gynaecological patientsACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 7 2005B. S. Von Ungern-Sternberg Background:, There is limited data comparing the impact of spinal anaesthesia (SA) and general anaesthesia (GA) on perioperative lung function. Here we assessed the differences of these two anaesthetic techniques on perioperative lung volumes in normal-weight (BMI < 25) and overweight (BMI 25,30) patients using spirometry. Methods:, We prospectively studied 84 consenting patients having operations in the vaginal region receiving either GA (n = 41) or SA (n = 43). Both groups (GA and SA) were further divided into two subgroups each (normal-weight vs. overweight). We measured vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), midexpiratory (MEF25-75) and peak expiratory flow rates (PEFR) at the preoperative assessment (baseline), after premedication, after effective SA, and 20 min, 1 h, 2 h and 3 h after the operation (last measurement after patient mobilization). Results:, Premedication was associated with a small but significant decrease in lung volumes in direct correlation with BMI (,5%). Spinal anaesthesia resulted in a significant reduction in lung volumes in overweight as opposed to normal-weight patients. Postoperatively, lung volumes were significantly more reduced following GA than SA as indicated by differences in mean VC (SD) of ,12 (6)% vs. ,6 (5)% 20 min after the end of the operation in the normal-weight and ,18 (5)% vs. ,10 (5)% in the overweight patients. There was a significant impact of BMI on postoperative respiratory function, which was significantly more important in the GA group than in the SA group, and recovery of lung volumes was more rapid in the normal-weight patients than in the overweight patients, particularly in the SA group. Conclusion:, In gynaecological patients undergoing vaginal surgery, the impact of anaesthesia on postoperative lung function as assessed by spirometry was significantly less after SA than GA, particularly in overweight patients. [source] Mechanical ventilatory constraints during incremental cycle exercise in human pregnancy: implications for respiratory sensationTHE JOURNAL OF PHYSIOLOGY, Issue 19 2008Dennis Jensen The aim of this study was to identify the physiological mechanisms of exertional respiratory discomfort (breathlessness) in pregnancy by comparing ventilatory (breathing pattern, airway function, operating lung volumes, oesophageal pressure (Poes)-derived indices of respiratory mechanics) and perceptual (breathlessness intensity) responses to incremental cycle exercise in 15 young, healthy women in the third trimester (TM3; between 34 and 38 weeks gestation) and again 4,5 months postpartum (PP). During pregnancy, resting inspiratory capacity (IC) increased (P < 0.01) and end-expiratory lung volume decreased (P < 0.001), with no associated change in total lung capacity (TLC) or static respiratory muscle strength. This permitted greater tidal volume (VT) expansion throughout exercise in TM3, while preserving the relationship between contractile respiratory muscle effort (tidal Poes swing expressed as a percentage of maximum inspiratory pressure (PImax)) and thoracic volume displacement (VT expressed as a percentage of vital capacity) and between breathlessness and ventilation . At the highest equivalent work rate (HEWR = 128 ± 5 W) in TM3 compared with PP: , tidal Poes/PImax and breathlessness intensity ratings increased by 10.2 l min,1 (P < 0.001), 8.8%PImax (P < 0.05) and 0.9 Borg units (P < 0.05), respectively. Pulmonary resistance was not increased at rest or during exercise at the HEWR in TM3, despite marked increases in mean tidal inspiratory and expiratory flow rates, suggesting increased bronchodilatation. Dynamic mechanical constraints on VT expansion (P < 0.05) with associated increased breathlessness intensity ratings (P < 0.05) were observed near peak exercise in TM3 compared with PP. In conclusion: (1) pregnancy-induced increases in exertional breathlessness reflected the normal awareness of increased and contractile respiratory muscle effort; (2) mechanical adaptations of the respiratory system, including recruitment of resting IC and increased bronchodilatation, accommodated the increased VT while preserving effort,displacement and breathlessness, relationships; and (3) dynamic mechanical ventilatory constraints contributed to respiratory discomfort near the limits of tolerance in late gestation. [source] Relationship between changes in interferon-, production by peripheral blood T cells and changes in peak expiratory flow rate in patients with chronic stable asthmaCLINICAL & EXPERIMENTAL ALLERGY, Issue 12 2002Y. I. Koh Summary Background Cytokines production by T helper lymphocytes (Th cells), which orchestrate the interplay of the different cells involved in airway inflammation of asthma, may be reflected in peripheral blood. Some studies have suggested that the Th cell cytokines by peripheral blood T cells correlate with asthma severity. Objective To investigate the relationship between changes in IFN-, production by peripheral blood T cells and changes in lung function in chronic stable asthmatics. Methods Sixteen patients with chronic stable moderate asthma aged 35,65 years (nine women) were recruited. Morning and evening peak expiratory flow rates (PEFR) monitoring and blood sampling for peripheral blood T cell culture, total IgE and blood eosinophils were performed at baseline and week 12. Levels of IFN-,, IL-4 and IL-5 in culture supernatants of peripheral blood T cell were determined by using enzyme-linked immunosorbent assay (ELISA) kits. Results Patients with increased IFN-, changes from baseline showed significantly increased changes in morning (P = 0.02) and evening (P < 0.05) PEFR compared with those with decreased IFN-, changes. The changes in IFN-, production and IFN-,: IL-4 ratio significantly correlated with the changes in morning PEFR (Rs = 0.59, P < 0.02; Rs = 0.63, P < 0.01, respectively) and tended to correlate with the changes in evening PEFR (Rs = 0.45, P = 0.08; Rs = 0.5, P = 0.05, respectively). The changes in IL-4 and IL-5 did not correlate with the changes in IgE and blood eosinophils, respectively. Conclusions These findings suggest that IFN-, may be associated with the alteration of lung function in asthmatics and play a role in the pathophysiology of chronic stable asthma. [source] | |||||||||||||||||||