Nickolaos G. Koulouris

Effects of exercise-induced arterial hypoxaemia and work rate on diaphragmatic fatigue in highly trained endurance athletes

Diaphragmatic fatigue occurs in highly trained athletes during exhaustive exercise. Since approximately half of them also exhibit exercise‐induced arterial hypoxaemia (EIAH) during high‐intensity exercise, the present study sought to test the hypothesis that arterial hypoxaemia contributes to exercise‐induced diaphragmatic fatigue in this population. Ten cyclists (: 70.0 ± 1.6 ml kg−1 min−1; mean ±s.e.m.) completed, in a balanced ordering sequence, one normoxic (end‐exercise arterial O2 saturation (S  a,O 2 ): 92 ± 1%) and one hyperoxic (F  I,O 2: 0.5% O2; S  a,O 2 : 97 ± 1%) 5 min exercise test at intensities equal to 80 ± 3 and 90 ± 3% of maximal work rate (WRmax), respectively, producing the same tidal volume (VT) and breathing frequency (f) throughout exercise. Cervical magnetic stimulation was used to determine reduction in twitch transdiaphragmatic pressure (Pdi,tw) during recovery. Hyperoxic exercise at 90% WRmax induced significantly (P= 0.022) greater post‐exercise reduction in Pdi,tw (15 ± 2%) than did normoxic exercise at 80% WRmax (9 ± 2%), despite the similar mean ventilation (123 ± 8 and 119 ± 8 l min−1, respectively), breathing pattern (VT: 2.53 ± 0.05 and 2.61 ± 0.05 l, f: 49 ± 2 and 46 ± 2 breaths min−1, respectively), mean changes in Pdi during exercise (37.1 ± 2.4 and 38.2 ± 2.8 cmH2O, respectively) and end‐exercise arterial lactate (12.1 ± 1.4 and 10.8 ± 1.1 mmol l−1, respectively). The difference found in diaphragmatic fatigue between the hyperoxic (at higher leg work rate) and the normoxic (at lower leg work rate) tests suggests that neither EIAH nor lactic acidosis per se are likely predominant causative factors in diaphragmatic fatigue in this population, at least at the level of S  a,O 2 tested. Rather, this result leads us to hypothesize that blood flow competition with the legs is an important contributor to diaphragmatic fatigue in heavy exercise, assuming that higher leg work required greater leg blood flow.

Methods for Assessing Expiratory Flow Limitation during Tidal Breathing in COPD Patients

Patients with severe COPD often exhale along the same flow-volume curve during quite breathing as during forced expiratory vital capacity manoeuvre, and this has been taken as indicating expiratory flow limitation at rest (EFLT). Therefore, EFLT, namely, attainment of maximal expiratory flow during tidal expiration, occurs when an increase in transpulmonary pressure causes no increase in expiratory flow. EFLT leads to small airway injury and promotes dynamic pulmonary hyperinflation with concurrent dyspnoea and exercise limitation. In fact, EFLT occurs commonly in COPD patients (mainly in GOLD III and IV stage) in whom the latter symptoms are common. The existing up-to-date physiological methods for assessing expiratory flow limitation (EFLT) are reviewed in the present work. Among the currently available techniques, the negative expiratory pressure (NEP) has been validated in a wide variety of settings and disorders. Consequently, it should be regarded as a simple, non invasive, most practical, and accurate new technique.

The role of non-invasive modalities for assessing inflammation in patients with non-cystic fibrosis bronchiectasis

Introduction Bronchiectasis is a heterogeneous entity, taking into account clinical characteristics, inflammatory response, effectiveness of treatment and frequency of exacerbations. In stable state non‐cystic fibrosis (non‐CF) bronchiectasis, little is known about non‐invasive techniques used for evaluating airway inflammation in obstructive airway diseases. Objectives We sought to evaluate the associations between induced sputum and clinical/radiologic characteristics, and the differences between biomarkers expressing Th1 and Th2 response in patients with non‐CF bronchiectasis and to compare our findings with a previously studied population of patients with asthma and COPD. Methods We evaluated prospectively collected data from subjects with bronchiectasis. Comparisons were made between clinical, radiographic and physiologic characteristics, as well as induced sputum markers using appropriate statistical tools. We compared the levels of sputum markers with those of a previously studied cohort of asthma and COPD patients. Results We enrolled 40 subjects (21 men, mean age 63.5 yrs) with bronchiectasis. Fifteen subjects (37.5%) had a neutrophilic phenotype, 7 (17.5%) had an eosinophilic phenotype, 3 (12.5%) had a mixed neutrophilic‐eosinophilic phenotype and 15 (37.5%) had a paucigranulocytic phenotype. Subjects with sputum neutrophilia had more severe bronchiectasis in HRCT and higher levels of IL‐8 in sputum, whereas subjects with eosinophilia had higher levels of FeNO, greater bronchodilator reversibility and higher sputum IL‐13. Sputum IL‐8 levels were higher in subjects exhibiting frequent exacerbations and correlated with neutrophils in sputum (r = 0.799), the extent of bronchiectasis in HRCT (r = 0.765) and post‐bronchodilator FEV1 (r = −0.416). Sputum IL‐13 levels correlated with sputum eosinophils (r = 0.656) and bronchodilator reversibility (r = 0.441). Neutrophilic bronchiectasis exhibited comparable IL‐8 levels to COPD, whereas eosinophilic bronchiectasis showed significantly lower IL‐13 levels compared to asthma. Conclusions Sputum cell counts and IL‐8 and IL‐13 correlate with distinct clinical and functional measurements of disease severity and therefore may have a role for non‐invasively assessing inflammation in non‐cystic fibrosis bronchiectasis. HighlightsInduced sputum is used for assessing airway inflammation in non‐CF bronchiectasis.Interleukin levels in induced sputum may correlate with disease severity.IL‐8 and IL‐13 levels were compared with clinical and laboratory characteristics.IL‐8 was associated with sputum neutrophilia and greater disease severity.IL‐13 was associated with sputum eosinophilia and bronchodilator reversibility.

Effect of pulmonary rehabilitation on tidal expiratory flow limitation at rest and during exercise in COPD patients

We hypothesized that severe COPD patients who present with the disadvantageous phenomenon of Expiratory Flow Limitation (EFL) may benefit as COPD patients without EFL do after implementation of a Pulmonary Rehabilitation (PR) program. Forty-two stable COPD patients were studied at rest and during exercise. EFL and dynamic hyperinflation (DH) were documented using the negative expiratory pressure (NEP) technique and inspiratory capacity (IC) maneuvers, respectively. Patient centered outcomes were evaluated by the Saint-Georges Respiratory Questionnaire (SGRQ) and the mMRC dyspnea scale. Before PR, 16 patients presented with EFL at rest and/or during exercise. After PR, EFL was abolished in 15 out of those 16 EFL patients who exhibited a significant increase in IC values. These were mainly accomplished through a modification of the breathing pattern. In the 26 NFL patients no increase was noted in their IC or a modification of their breathing pattern. However, both NFL and EFL COPD patients improved exercise capacity and patients centered outcomes undergoing the same PR program.

Gaining access to the periphery of the lung: Bronchoscopic and transthoracic approaches

Globally, lung cancer remains the leading cause of cancer-related death. Annual low-dose computed tomography has been recommended as a screening test for early detection of lung cancers. Implementing this screening strategy is expected to challenge pulmonologist to confirm the nature of the increasing number of detected pulmonary nodules. Clinicians are obliged to use the less invasive and most efficient and safe means to set diagnoses. Hence, the field of diagnostic modalities, especially the advanced diagnostic bronchoscopy is witnessing rapid evolution to fulfill these unmet needs. This review highlights the available diagnostic modalities, describes their advantages and discusses the limitations of each technique. It also suggests an integrated diagnostic algorithm based on the best available evidence. A search of the PubMed database was conducted using relevant terms described at methodology; only articles in English were reviewed by November 2016.

Prediction of Postoperative Lung Function in Patients With Lung Cancer: The Role of Quantitative CT Imaging

We thank Drs Myrianthefs and Baltopoulos for the data reported in their letter. They used the results of our recently published study in CHEST 1 to evaluate the different economic outcomes of patients in the ICU with ventilator-associated pneumonia (VAP) treated with IV colistin monotherapy or aerosolized plus IV (AS 1 IV) colistin therapy in a Greek hospital. They found that 7-day AS 1 IV colistin therapy is less expensive than 10-day IV colistin monotherapy. They also found that a considerable cost benefi t may occur as a result of fewer days under mechanical ventilation (MV) and shorter length of ICU stay. Of course, we agree with them that the use of AS 1 IV colistin therapy can be a costeffective strategy in patients with VAP, shortening the duration of therapy, MV, and ICU stay and achieving better clinical outcomes. Because our study was retrospective, a proper cost assessment was not completely reliable, especially in the absence of parameters whose prospective collection would have been important (ie, those related to nurse workload). Consequently, we preferred to not speculate on the cost-benefi t analysis. As the total length of hospitalization is the main cost driver, in our institution a considerable cost benefi t would also be expected as a result of fewer days under MV and shorter ICU length of stay. In conclusion, the cost-effectiveness of AS 1 IV colistin therapy for the management of VAP caused by multidrug-resistant gram-negative bacteria should be an important end point to be further investigated in multicenter prospective randomized clinical trials.