Ventilatory Capacity Research Articles

Abdominal muscle fatigue following exercise in chronic obstructive pulmonary disease

BackgroundIn patients with chronic obstructive pulmonary disease, a restriction on maximum ventilatory capacity contributes to exercise limitation. It has been demonstrated that the diaphragm in COPD is relatively protected from fatigue during exercise. Because of expiratory flow limitation the abdominal muscles are activated early during exercise in COPD. This adds significantly to the work of breathing and may therefore contribute to exercise limitation. In healthy subjects, prior expiratory muscle fatigue has been shown itself to contribute to the development of quadriceps fatigue. It is not known whether fatigue of the abdominal muscles occurs during exercise in COPD.MethodsTwitch gastric pressure (TwT10Pga), elicited by magnetic stimulation over the 10th thoracic vertebra and twitch transdiaphragmatic pressure (TwPdi), elicited by bilateral anterolateral magnetic phrenic nerve stimulation were measured before and after symptom-limited, incremental cycle ergometry in patients with COPD.ResultsTwenty-three COPD patients, with a mean (SD) FEV1 40.8(23.1)% predicted, achieved a mean peak workload of 53.5(15.9) W. Following exercise, TwT10Pga fell from 51.3(27.1) cmH2O to 47.4(25.2) cmH2O (p = 0.011). TwPdi did not change significantly; pre 17.0(6.4) cmH2O post 17.5(5.9) cmH2O (p = 0.7). Fatiguers, defined as having a fall TwT10Pga ≥ 10% had significantly worse lung gas transfer, but did not differ in other exercise parameters.ConclusionsIn patients with COPD, abdominal muscle but not diaphragm fatigue develops following symptom limited incremental cycle ergometry. Further work is needed to establish whether abdominal muscle fatigue is relevant to exercise limitation in COPD, perhaps indirectly through an effect on quadriceps fatigability.

Clinical Implications of Pulmonary Function Tests in Allogeneic Stem Cell Recipients.

Abstract 4297Pulmonary dysfunction is one of major causes of morbidity and mortality in the allogeneic stem cell recipients. From Jun 2002 to Oct 2008, we retrospectively analyzed pulmonary functions (PF) in 116 consecutive patients who received allogeneic stem cell transplantation (SCT) and survived at least 3 months after transplantation. Pulmonary function test was performed at baseline, 3 months, 6 months, 1 year, and annually thereafter. Ventilatory capacity was measured by forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), and FEV1/FVC ratio. Lung volume measurements included total lung capacity (TLC), residual volume (RV), and RV/TLC ratio. Diffusion capacity for carbon monoxide (DLCO) was determined with correction for hemoglobin concentration. Of the 116 patients, 63 patients were followed more than 1 year. The patients with acute graft-versus-host disease (GVHD; p=0.011), chronic GVHD (p=0.009), or CMV infection (p=0.410) showed a decline of FEV1 and FEV1/FVC after 1 year of transplantation. TLC and RV/TLC also showed an increasing tendency after 1 year of transplantation which reflected abnormal ventilatory pulmonary function. Conditioning intensity, unrelated donor type, stem cell dose did not adversely affect the pulmonary function. We calculated the lung function score (defined as FEV1 score plus DLCO score; NIH chronic GVHD consensus Project, 2003) at 1 year of transplant and compared it from that of baseline to identify the factors affecting late pulmonary dysfunction. In the multivariate analysis, extensive cGVHD (OR=3.692, 95% CI=1.154-11.818; p=0.028) and previous CMV infection (OR=5.356, 95% CI=1.311-21.882; p=0.019) negatively affected on late pulmonary function. In addition, the patients with early decline of FEV1 more than 10% at 3 months compared to baseline showed a higher incidence of cGVHD during follow-up (p=0.016). In conclusion, patients who had extensive cGVHD or CMV infection had a higher possibility of late pulmonary dysfunction and decline of FEV1 at 3 months of transplantation reflected the development of cGVHD. Disclosures:No relevant conflicts of interest to declare.

Respiratory Symptoms and Ventilatory Capacity in Metal Polishers

ISEE-0090 Abstract: To evaluate the long term effects of metal dusts on the bronchopulmonary system and the synergistic effect of cigarette smoke, a comparative study of spirometric measurements in 104 polishers and 90 unexposed controls was carried out in 25 brass and steelware polishing industries at Moradabad in northern India. The two groups were comparable in terms of age, height, smoking habit and socio-economic status. A total of 58.6% of the polishers had one or more respiratory symptoms, compared to only 25.5% of the controls (P < 0.05). Chronic cough was present in 21 polishers (20.2%) as compared to 11.1% of the controls. However, this difference was insignificant. Chronic phlegm was nearly three times as frequent among the polishers as among the controls (17.5% vs 4.4%) (P < 0.005). The prevalence of dyspnoea of varying grades was also significantly higher (16.3% as opposed to 4.4%) among the exposed groups. Chronic bronchitis (6.7%) and occupational asthma (4.8%) were found to be confined to polishers. The polishers also experienced acute respiratory symptoms during the work shift. Comparison of the mean values of pulmonary function parameters in the polishers and the controls showed significant differences in the smoking and non-smoking groups. (P < 0.001). The polishers exhibited significantly greater acute reductions in various lung functions over the work shift, particularly for forced expiratory flow over the 25-75% portion of the spirogram (FEF25-75%) FEF25% and FEF50%, than did the controls. Among the exposed group, the acute changes in lung function were found to be significantly larger in the smoking than in the non-smoking polishers. Polishers who were exposed to dusts of various metals for more than 10 years showed a significantly greater acute reduction in all pulmonary function tests (P < 0.001) thereby indicating that occupational exposure to multiple metals in the work environment of the polishing industry had deleterious respiratory effects.

Is there still a place for the conservative treatment of idiopathic scoliosis in children and adolescents?

In the existing literature, studies on this subject are not always consistent; hence the results of the orthopaedic treatment in scoliosis are difficult to interpret. Actually, the main difficulty lies in the insufficiency of available data on the features of the treated cases of scoliosis: few or no clinical data recorded at the beginning of the treatment and over the whole follow-up period, especially with regard to the evaluation of hump deformity, the measurement of frontal and sagittal tilt angle, changes of ventilatory capacity, etc., bone age at the start and at the end of the treatment, and to the known extent of the scoliosis.

Tim-3 mRNA expression in peripheral blood lymphocytes from asthmatic patients

The study aimed to detect the expression of the Th1-specific cell surface protein T cell Ig and mucin domain-containing molecule-3 (Tim-3) mRNA in peripheral blood lymphocytes isolated from asthmatic patients and to examine the correlation among Tim-3 mRNA, interleukin-4 (IL-4), interferon-γ (IFN-γ) level, and FEV1/FVC (force expiratory volume in one second/forced vital capacity) to explore the role of Tim-3 in the development and progression of asthmatic inflammation. Tim-3 mRNA expression was detected by reverse transcription polymerase chain reaction (RT-PCR). The IL-4 and IFN-γ levels were determined by using enzyme-linked immunosorbent assay (ELISA). The correlation among Tim-3 mRNA, IL-4, IFN-γ level, and pulmonary ventilatory capacity was analyzed. The expression of Tim-3 mRNA in patients with acute asthma exacerbation was 0.39±0.06, significantly higher than that in patients at the remission stage and controls (0.18±0.05 and 0.07±0.03, P<0.05). The level of IL-4 in patients with acute asthma exacerbation was 68.42±10.54, significantly higher than that in the patients at the remission stage and controls (41.83±9.37 and 32.75±8.16, P<0.05). The level of IL-4 in patients in remission was significantly higher than that in controls (P<0.05). The level of IFN-γ in patients with acute asthma exacerbation was 65.74±7.85, significantly lower than that in patients in remission and the control group (120.84±11.62 and 139.65±13.47, P<0.05). The level of IFN-γ in patients in asthma remission was significantly lower than that in controls (P<0.05). Tim-3 mRNA expression was positively correlated with the level of IL-4 (r = 0.68, P<0.05) and negatively with the level of IFN-γ and pulmonary ventilatory capacity (r = − 0.85 r = − 0.76, both P<0.01). The increased expression of Tim-3 mRNA in peripheral blood lymphocytes might be involved in the development and progression of asthmatic inflammation

Ventilatory impairment in a rat model of central dysmyelination

Although respiratory complications are the major cause of morbidity/mortality in advanced myelin disorders (i.e. MS), little is known concerning mechanisms whereby lack of myelin impairs ventilation, or how patients compensate for such changes (i.e. plasticity). To establish a model for future studies concerning mechanisms of ventilatory impairment/compensation, we tested the hypothesis that respiratory function progressively declines with advancing disease in a genetic model of CNS dysmyelination, the Long Evans shaker rat (les). Ventilatory measurements were made via whole‐body plethysmography in les and wild‐type rats at baseline and during hypercapnia (7%CO2). In young (P59) rats, there were no differences in breathing between les and wild‐type groups in either condition (p&gt;0.05). However, by P150, significant decreases between groups were observed in mean inspiratory flow (Vt/Ti), breathing frequency and minute ventilation during baseline (40%, 47% and 37%, respectively) and hypercapnia (40%, 44% and 50%, respectively) (all p&lt;0.05). Thus, ventilatory capacity is maintained in young, dysmyelinated rats, but ventilatory impairment develops as les rats age. This study provides the foundation for mechanistic studies of respiratory insufficiency and therapeutic interventions in myelin disorders. Support: NIH NS057778, UW ICTR via NIH CTSA 1UL1RR025011, NMSS TR3761

Serotonin depletion near end‐stage disease does not impair ventilation in a rat model of amyotrophic lateral sclerosis (ALS)

In rodent models of ALS (SOD1G93A rat), ventilation is maintained until late in disease progression, despite a paucity of surviving respiratory motor neurons. Thus, surviving motor neurons compensate for motor neuron loss and preserve ventilation. We tested the hypothesis that 5‐HT is necessary for such compensatory plasticity by measuring ventilatory capacity following 5‐HT depletion near disease end stage in SOD1G93A rats. When SOD1G93A rats decreased body mass 15%, mutants (and wild type litter mates) were given para‐chlorophenylalanine (PCPA; 300 mg/kg IP) or vehicle injections (0.9% NaCl, 7.5 ml/kg IP) for 2 days. Ventilatory measurements were made during baseline, hypoxic (10.5% O2), hypercapnic (7% CO2) and hypoxic/hypercapnic (10.5% O2/7% CO2) conditions via whole‐body plethysmography (n=3‐5 per group). PCPA had no effect (or actually increased) minute ventilation and tidal volume in all conditions studied in both mutant and wild type rats. PCPA decreased breathing frequency (f) in wild type rats; although f was lower in untreated mutant rats (vs wild type), PCPA had no additional effect. Our data provide no evidence that 5‐HT depletion impairs the capacity to increase ventilation in end‐stage SOD1G93A rats. However, we cannot rule out a role for 5‐HT in the induction (vs maintenance) of compensatory plasticity in SOD1G93A rats.[Supported by NIH NSO57778.]

Validation of self-reported chronic obstructive pulmonary disease among patients in the ED

Background To determine whether the self-reported diagnosis of adults who present to the emergency department (ED) with an acute exacerbation of either asthma or chronic obstructive pulmonary disease (COPD) is validated by medical record review. Methods This is cross-sectional study of 78 consecutive adults, 55 years and older, presenting to 3 EDs with symptoms suggestive of an exacerbation of asthma or COPD. We used current spirometric guidelines for a “spirometrically validated” diagnosis of COPD (eg, postbronchodilator forced expiratory volume in 1 second/forced ventilatory capacity <70%). Patients without office spirometry result were classified with COPD using clinical validation based on at least one of the following: primary care physician diagnosis of COPD, chronic bronchitis, or emphysema in the medical record or chest radiography, chest computed tomography, or arterial blood gas (ABG) diagnostic of COPD. Results Among 60 patients who self-reported diagnosis of COPD, 98% (95% confidence interval, 89-100) had clinically validated or spirometrically validated COPD. In addition, 83% (95% confidence interval, 59-96) of patients who reported either asthma only or no respiratory disease had clinically validated or spirometrically validated COPD. In no case was the chest radiograph or the ABG useful as a stand-alone test in establishing the diagnosis of COPD. Conclusions Patients 55 years and older presenting to the ED with acute asthma or COPD, even those with clinical symptoms but no diagnosis of COPD, are likely to have COPD. Clinicians should maintain a high index of suspicion for COPD when older asthma patients deny COPD.

Late Pulmonary Dysfunction in Long-Term Survivors after allogeneic Hematopoietic Stem Cell Transplantation with Intensified Conditioning Regimen Including Thiotepa, Cyclophosphamide, and Total Body Irradiation.

Background: Late pulmonary dysfunction is a clinical problem influencing on quality-of-life (QOL) in long-term survivors after allogeneic hematopoietic stem cell transplantation (HSCT). In this study we retrospectively assessed pulmonary function test (PFT) in patients surviving 5 years or more after HSCT with intensified conditioning regimen and identified pre-and post-transplant risk factors.Methods: Sixty-five long-term survivors transplanted between May 1994 and March 2003 (minimum 5 years follow-up after HSCT) were included in this analysis. There were 36 males and 29 females. Median age was 39 years, with a range of 16 to 53 years. All patients were transplanted because of hematologic malignancies (20 patients with AML, 16 with ALL, 9 with MDS, and 20 with CML). The pre-transplant conditioning regimen consisted of thiotepa (200 mg/m2 for 2 days), cyclophosphamide (2,000–2,250 mg/m2 for 2 days), and total body irradiation (12.5 Gy in five fractions). The prophylaxis of graft-versus-host disease (GVHD) consisted of short-term methotrexate and cyclosporine or tacrolimus. Bone marrow (BM) from related donor or unrelated donor, and peripheral blood stem cell (PBSC) from related donor were transplanted in 33 patients, 22, and 10, respectively. PFT was performed pre-conditioning and then post-transplant at 3 months, 1 year, and thereafter annually. Forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), and FEV1/FVC ratio were used to measure ventilatory capacity. Vital capacity (VC) and total lung capacity (TLC) were used to measure lung volumes. Diffusion capacity for carbon monoxide (DLCO) was determined by using a carbon monoxide single-breath technique with correction for hemoglobin concentration.Results: Seven (11%) patients showed abnormalities in PFT after HSCT. Temporary abnormality (restrictive pattern) within 1 year was detected in 2 patients. Five patients developed late-onset and continuous abnormality (restrictive pattern in 2 patients, obstructive in 2, and mixed in 2) with a cumulative incidence of 8%. These were clinically diagnosed as having bronchiolitis obliterans in 3 patient and interstitial pneumonia in 1. DLCO was significantly lower after transplantation of PBSC than after BM (P=0.02 at 3 year and P=0.00 3 at 5 year). More than 40 years old, female, high risk of disease status, and abnormal PFT pre-transplant were related with a decline of PFT within 1 year after HSCT, but there were no association with PFT abnormality at 3 or 5 years. The cumulative incidence of late PFT abnormality in patients with CML was significantly higher than that in those with other than CML (P=0.01).Other factors including age, sex, smoking, disease status, and donor sources were not significant for developing late pulmonary dysfunction. Extensive chronic GVHD was associated with late PFT abnormality with statistical significance (P=0.002 for VC and P=0.01 for FEV1). Three of 7 patients receiving immunosuppressant at 5 years after HSCT had pulmonary complication.Conclusions: The results showed relatively a low incidence of PFT abnormality in long-term survivors who received HSCT with intensified conditioning regimen. However, late pulmonary dysfunction lowers QOL in survivors despite long-term remission of leukemia Longer follow-up should be needed to determine whether more patients with chronic GVHD will develop PFT abnormality.

Respiratory Function in Pesticide Workers

Pesticide aerosols are frequently toxic irritants associated with respiratory symptoms and lung function impairment. A cross-sectional study examined the prevalence of acute and chronic respiratory symptoms and lung function abnormalities in 82 workers employed in processing pesticides and in 60 control workers not exposed to irritants and employed in a soft drink bottling plant. The prevalence of almost all chronic respiratory symptoms was greater among pesticide workers than among controls. A logistic regression analysis shows differences between men and women. There was a high prevalence of acute symptoms during the work shift in pesticide workers. The data on ventilatory capacity indicates significant reductions in all tests compared to predicted. Multivariate analysis of lung function showed differences in smoking and work exposure effects in men and women. Our data indicate that duration of work exposure in the pesticide processing industry may be associated with the development of acute and chronic respiratory symptoms and lung function changes. These effects appear to be aggravated by smoking.

2080 Relationship of structural and functional cardiac abnormalities to respiratory status in Duchenne Muscular Dystrophy

Methods Retrospective cross-sectional study of 40 DMD subjects evaluated from 2004–2006. Each patient underwent standard pulmonary function testing and CMR for clinical indications (mean = 9 months between studies). Collected data included FVC% predicted (FVC%, a marker of ventilatory capacity) and FEV1%; Ejection fraction (LVEF, RVEF), end-diastolic volume (LVEDV, RVEDV), and enddiastolic mass (LVEDM, RVEDM). Spearman rank correlations were performed between pulmonary and cardiac parameters.

Changes in ventilatory capacity, exercise capacity, and pulmonary blood flow after lobectomy in patients with lung cancer - which lobectomy has the most loss in exercise capacity?

The aim of this study was to compare the changes in ventilatory capacity, exercise capacity, and pulmonary blood flow (PBF) in the operated lung after lobectomy according to the lobe resected. Thirty-one patients underwent right upper lobectomy (RUL), 26 left upper lobectomy (LUL), 24 right lower lobectomy (RLL), and 25 left lower lobectomy (LLL). Pulmonary function tests, exercise capacity tests, and perfusion lung scans were performed preoperatively and six months to one year after lobectomy. RUL was associated with significantly less loss in forced vital capacity (FVC) than RLL or LLL (P<0.05). LUL was associated with the greatest loss in maximum oxygen consumption (VO2) (P<0.05). LUL was associated with significantly greater loss in PBF in the operated lung than RUL (P<0.05). LUL had a significantly higher negative value in percentage change in (VO2) --percentage change in FVC, and percentage change in PBF--percentage change in FVC than RLL or LLL (P<0.05). LUL was not associated with the greatest loss in ventilatory capacity or PBF, although it was associated with the greatest loss in . Each lobectomy has its own peculiarity in magnitude of loss in (VO2), PBF or FVC.

Ventilatory Capacity and Its Utilisation During Exercise

Inadequate ventilation is not usually considered an exercise-limiting factor because it is thought that the respiratory system's maximum ventilatory capacity is never reached during exercise. This so-called reserve can be defined as the difference between the ventilated volume, attained during a maximum voluntary ventilation manoeuvre (MVV) and the maximum ventilation V(Emax) achieved during exercise. This study explores the relationship between ventilatory capacity, the MVV manoeuvre, and respiratory function. Twelve healthy adults completed a maximal cycle test and 12-, 30-, and 60-s MVV manoeuvres while seated or standing. The MVV(12) manoeuvre produced the largest ventilation volume (115 +/- 22 vs. (V(Emax)) 102 +/- 23 L min(-1)), signifying a reserve of 13%. With longer MVV (30 and 60 s) manoeuvres, the ventilated volume and (V(Emax)) were the same, signifying no reserve. MVV increased with the forced expiratory volume at one second, FEV(1). The breath rates were approximately 120 vs. 48 +/- 6 breaths min(-1) and tidal volumes were approximately 1 vs. 2.2 +/- 0.5 L during the MVV and exercise, respectively. The longer MVV manoeuvre provides the best estimate of ventilatory capacity and shows that 100% of the reserve is used during maximal exercise. A nomogram relating MVV to FEV(1) is shown.

Sex differences in the perceived intensity of breathlessness during exercise with advancing age

The prevalence of activity-related breathlessness increases with age, particularly in women, but the specific underlying mechanisms have not been studied. This novel cross-sectional study was undertaken to examine the effects of age and sex, and their interaction, on the perceptual and ventilatory responses to incremental treadmill exercise in 73 healthy participants (age range 40-80 yr old) with normal pulmonary function. Age-related changes at a standardized oxygen uptake (Vo(2)) during exercise included significant increases in breathlessness ratings (Borg scale), ventilation (Ve), ventilatory equivalent for carbon dioxide, and the ratio of tidal volume (Vt) to dynamic inspiratory capacity (IC) (all P < 0.05). These changes were quantitatively similar in women (n = 39) and in men (n = 34). For the group as a whole, exertional breathlessness ratings increased as resting static inspiratory muscle strength diminished (P = 0.05), as exercise ventilation increased relative to capacity (P = 0.013) and as the Vt/IC ratio increased (P = 0.003) during exercise. Older women (60-80 yr old, n = 23) reported greater (P < 0.05) intensity of exertional breathlessness at a standardized Vo(2) and Ve than age-matched men (n = 16), despite similar age-related changes in ventilatory demand and dynamic ventilatory mechanics. These increases in breathlessness ratings in older women disappeared when sex differences in baseline maximal ventilatory capacity were accounted for. In conclusion, although increased exertional breathlessness with advancing age is multifactorial, contributory factors included higher ventilatory requirements during exercise, progressive inspiratory muscle weakness, and restrictive mechanical constraints on Vt expansion related to reduced IC. The sensory consequences of this age-related respiratory impairment were more pronounced in women, who, by nature, have relatively reduced maximal ventilatory reserve.

Exercise capacity after lobectomy in patients with chronic obstructive pulmonary disease

The aim of this study is to clarify whether patients with chronic obstructive pulmonary disease (COPD) lose less exercise capacity after lobectomy than do those without COPD, to the same extent as ventilatory capacity and lobectomy for selected patients with severe emphysema improve exercise capacity like ventilatory capacity. Seventy non-COPD patients (N group), 16 mild COPD patients (M group), and 14 moderate-to-severe COPD patients (S group) participated. Pulmonary function and exercise capacity tests were performed on the same day preoperatively and six months to one year after lobectomy. The S group lost significantly less FEV(1) (forced expiratory volume in 1 s) after lobectomy than did the N or M group (P<0.0001 and P<0.005). However, their loss of exercise capacity was equivalent to that for the N and M groups. For the S group, there was a significant, negative correlation between preoperative FEV(1) % of predicted and percentage change in FEV(1) and maximum oxygen consumption (VO2 max) after lobectomy (r=-0.93, P<0.0001 and r=-0.64, P=0.01). In moderate-to-severe COPD patients, patients with a lower preoperative FEV(1) % of predicted experienced a smaller decrease in FEV(1) and VO2 max after lobectomy.

Cadmium-dependent oxygen limitation affects temperature tolerance in eastern oysters (Crassostrea virginicaGmelin)

Marine ectotherms, including oysters are exposed to variable environmental conditions in coastal shallow waters and estuaries. In the light of global climate change, additional stressors like pollution might pose higher risk to populations. On the basis of the concept of oxygen- and capacity-limited thermal tolerance in aquatic ectotherms (40), we show that a persistent pollutant, cadmium, can have detrimental effects on oysters (Crassostrea virginica). During acute warming from 20 to 28 degrees C (4 degrees C/48 h) standard metabolic rate (SMR) rose in control and cadmium-exposed (50 microg Cd2+/l) animals, with a consistently higher SMR in Cd-exposed oysters. Additionally, Cd-exposed oysters showed a stronger temperature-dependent decrease in hemolymph oxygen partial pressures. This observation indicates that the effect of temperature on aerobic metabolism was exacerbated due to the additional Cd stress. The oxygen delivery systems could not provide enough oxygen to cover Cd-induced elevated metabolic demands at high temperatures. Interestingly, cardiac performance (measured as the heart rate and hemolymph supply to tissues) rose to a similar extent in control and Cd-exposed oysters with warming indicating that cardiac output was unable to compensate for elevated energy demand in Cd-exposed oysters. Together with the literature data on metal-induced reduction of ventilatory capacity, these findings suggest that synergistic effects of elevated temperatures and cadmium exposure led to oxygen limitation by impaired performance in oxygen supply through ventilation and circulation. Overall, cadmium exposure resulted in progressive hypoxemia in oysters at high temperatures, suggesting that the thermal tolerance window is narrowed in marine ectotherms inhabiting polluted areas compared with pristine environments.

The importance of diffusing capacity as a complementary study to plethysmography in smokers

This study comprised 194 male and female heavy smokers or ex-smokers (≥ 1 pack-year) aged between 20 and 82, whose symptoms varied. Cases were only selected from patients with normal whole-body plethysmography. Subjects with any significant pathology and occupational risk factors were excluded from the study.Varying degrees of symptoms were found and a range of results from normal plethysmography examination, with abnormal levels of alveolar-capillary transfer, determined by the single-breath method to analyse CO (TLCO and TLCO-VA) coefficients. Using the chi-square test for statistical analysis of the sample revealed a significant variation in sensitivity between both parameters (p=0.0001).Possible limitations of using the single-breath method, of were reduced in this study (ventilatory restriction withVital Capacity <1.5 litres) by the routine plethysmography results seen. Likewise, the presence of alterations in ventilatory distribution was, in principle, minimised by the absence of TLCsb/TLCplet values below 0.85% ConclusionsNormal plethysmography results in heavy or ex-smokers are not enough to confirm normal respiratory function, as a large percentage of cases present abnormalities in the alveolar-capillary transfer factor for CO. Alveolar limitation was considered not only anatomically, but also from a functional perspective.

A importância do estudo da difusão alvéolo-capilar, como complemento da pletismografia, na avaliação funcional de fumadores

This study comprised 194 male and female heavy smokers or ex-smokers (≥ 1 pack-year) aged between 20 and 82, whose symptoms varied. Cases were only selected from patients with normal whole-body plethysmography. Subjects with any significant pathology and occupational risk factors were excluded from the study.Varying degrees of symptoms were found and a range of results from normal plethysmography examination, with abnormal levels of alveolar-capillary transfer, determined by the single-breath method to analyse CO (TLCO and TLCO -VA) coefficients. Using the chi-square test for statistical analysis of the sample revealed a significant variation in sensitivity between both parameters (p=0.0001).Possible limitations of using the single-breath method, of were reduced in this study (ventilatory restriction withVital Capacity <1.5 litres) by the routine plethysmography results seen. Likewise, the presence of alterations in ventilatory distribution was, in principle, minimised by the absence of TLCsb/TLCplet values below 0.85%Conclusions: Normal plethysmography results in heavy or ex-smokers are not enough to confirm normal respiratory function, as a large percentage of cases present abnormalities in the alveolar-capillary transfer factor for CO. Alveolar limitation was considered not only anatomically, but also from a functional perspective.Rev Port Pneumol 2007; XIII (6): 763-774

Sildenafil appears to improve ventilatory efficiency and exercise capacity in patients with pulmonary hypertension

Sildenafil appears to improve ventilatory efficiency and exercise capacity in patients with pulmonary hypertension

Comparing the Airtraq® with the LMA CTrach ™

University of Washington, Seattle, Washington. agoldman@u.washington.eduI read with great interest the case report by Dhonneur et al. 1using the Airtraq® (King Systems, Noblesville, IN) optical laryngoscope after failed direct laryngoscopy in two patients requiring emergency cesarean delivery. Placing an Airtraq® (or any of the new video-laryngoscopes, e.g. , GlideScope®[Verathon, Bothell, WA], McGrath®[LMA North America, San Diego, CA]) as a brief plan B after a failed direct laryngoscopy in obstetrics may be an evolving new standard of practice for an emergency cesarean delivery. However, comparing the Airtraq® intubation time with the LMA CTrach ™ (LMA North America, San Diego, CA) intubation time (<1 min vs. 3 min) is not an entirely appropriate comparison.1The CTrach time of 3 min includes establishing ventilation and removing the CTrach airway after intubation is confirmed.2The ventilatory capacity of the CTrach is arguably equally important to its effectiveness as an intubation conduit during airway resuscitation.3It is well known how quickly a term parturient can desaturate during laryngoscopy. The CTrach (like the intubating laryngeal mask airway) is an effective ventilatory device with ventilatory success rates of greater than 99%.2,4If intubation is not successful, the presence of an effective airway can be lifesaving. The CTrach gives the operator time to optimize the laryngeal view and the patient's physiologic parameters before attempting intubation.3,5Liu et al. 2report a 99% first-pass intubation success in the 84% of patients whose larynx was seen on the CTrach monitor. In the remaining 16%, the CTrach functioned as an intubating laryngeal mask airway would, with corresponding intubation/ventilation success rates. Ventilation and oxygenation, not solely intubation, are the primary goals of effective airway resuscitation.University of Washington, Seattle, Washington. agoldman@u.washington.edu