Eef Vanderhelst

Lung clearance index in adult cystic fibrosis patients: The role of convection-dependent lung units

We investigated the extent of convective ventilation heterogeneity contributing to the observed lung clearance index values in adult cystic fibrosis patients, as the result of two simulated scenarios, either 1) a fixed part of the lungs becoming increasingly less compliant, or 2) an increasingly greater part of the lung being less compliant. In 25 cystic fibrosis patients and 25 matched controls, we computed the lung clearance index and also quantified curvilinearity of the washout concentration curve, where curvilinearity is equal to 0 (linear in semilog plot) reflects homogeneous ventilation and curvilinearity equal to 1 corresponds to the presence of an infinitesimally slowly emptying lung unit. In the cystic fibrosis group (forced expiratory volume in 1 s 27–100% predicted), lung clearance index and curvilinearity average±sd values were 10.3±2.3 and 0.57±0.13, respectively, and were significantly different from control values (6.2±0.4 and 0.18±0.07; both p<0.001); lung clearance index and curvilinearity were also correlated (R = 0.67; p<0.001). The average curvilinearity value in the cystic fibrosis group was found to be compatible with a cumulative volume of underventilated lung of 40–50%, depending on the simulation scenario considered. The degree of washout curvilinearity observed here indicates that a major determinant of the abnormal lung clearance index values observed in adult cystic fibrosis patients is ventilation heterogeneity generated between convection-dependent lung units, while the remainder of lung clearance index abnormality with respect to normal controls potentially represents the small airways within these lung zones.

Prevalence and impact on FEV1 decline of chronic methicillin-resistant Staphylococcus aureus (MRSA) colonization in patients with Cystic Fibrosis: A single-center, case control study of 165 patients

BACKGROUND Risk factors for methicillin-resistant Staphylococcus aureus (MRSA) in Cystic Fibrosis (CF) and the impact on CF disease progression are still under debate. The objectives of this study were to determine clinical variables associated with MRSA colonization and examine impact on FEV(1) evolution in CF patients. METHODS A retrospective case-control study using the University Hospital of Brussels CF clinic patient registry from 2002 to 2010, comparing clinical variables and decline of FEV(1) of MRSA positive patients with age and sex matched controls, chronically colonized with S. aureus. RESULTS Thirty of the 165 CF patients, chronically colonized with S. aureus, had cultures positive for MRSA (18.2%). Excluding patients under 4 years, the prevalence became 15.2% (23/151). Chronic colonization (i.e., three or more consecutive positive cultures) was found in 19/151 (12.6%). The MRSA positive group showed a higher proportion of patients with genotype F508del, less pancreas sufficient patients, more bronchiectasis and more frequent hospitalization. The FEV(1) recorded one year prior to, and at the moment of MRSA acquisition, was lower but not significantly different from that obtained in controls (72.9%±26.6 vs 84.3±21.8 and 68.2%±27.1 vs 81.4%±24.3 respectively, p>0.1). However, FEV(1) decline over 2- and 6-year periods, were significantly greater in the chronic MRSA group than in the controls (-5%±5.5 vs -2.5±2.3 over 2 years (p=0.043) and -1.8%±4.6 vs -1.0%±1.9 over a 6-year period (p=0.026)). CONCLUSION In our center the prevalence of MRSA in CF patients, chronically colonized with S. aureus and over the age of 4 years, was 15.2% (12.6% chronic infection). MRSA colonization was shown to be associated with a genotype F508del, presence of bronchiectasis and hospitalization. Our spirometric data also show that a MRSA episode entails an FEV(1) decline that is almost double that predicted for CF patients who can remain unaffected by MRSA.

Acinar and conductive ventilation heterogeneity in severe CF lung disease: back to the model.

Severe convective ventilation heterogeneity occurring in CF lung disease requires a modified method to determine acinar and conductive components of ventilation heterogeneity from normalized phase III slope (Sn) curves. Modified Sacin* and Scond* (as opposed to standard Sacin and Scond) are proposed and interpreted on the basis of 2 conceptual mechanisms: (a) flow asynchrony between two convection-dependent units with a different specific ventilation, but with an identical acinus inside each unit (generating an identical diffusion-convection-dependent portion of Sn); (b) different specific ventilation (without any flow asynchrony) between two convection-dependent units with the worst ventilated unit containing an abnormal acinus generating the greatest diffusion-convection-dependent portion of Sn. In CF patients with an abnormal lung clearance index (LCI), Scond* (but not Scond) and Sacin* were significant contributors to LCI (β(Scond*)=0.70; β(Sacin*)=0.49; P<0.001 for both). Mechanism (a) can entirely account for experimental Scond* values, while mechanism (b) implies that experimental Sacin* values are likely dominated by peripheral ventilation heterogeneity in the best ventilated portions of the lung.

Eradication of chronic methicillin-resistant Staphylococcus aureus infection in cystic fibrosis patients. An observational prospective cohort study of 11 patients

BACKGROUND Chronic airway infection with methicillin-resistant Staphylococcus aureus (MRSA) in patients with cystic fibrosis (CF) is an increasing clinical problem, and therapeutic options are limited. Because chronic infection with MRSA can be associated with accelerated decline in lung function, eradication of MRSA is attempted in most CF centres today. The aim of this observational prospective cohort study was to determine whether it is possible to eradicate MRSA from airways of CF patients using prolonged oral antibiotic combination therapy together with topical decolonization measures. RESULTS Eleven CF patients, (median age: 9 years (range 1-43); median FEV1: 91%pred (95%CI 74%-100%pred)) who were chronically infected with MRSA, were treated daily for six months with rifampicin and fusidic acid orally. This study did not include a patient control group. Two patients had to switch to an alternative schedule, using rifampicin and clindamycin, due to the resistance pattern of MRSA. Topical decolonization measures were applied to all patients and included mupirocin-containing nasal ointment in both nostrils three times daily for five days and chlorhexidine hair and body wash once daily for five days. Microbiological eradication was achieved in all patients at the end of the six-month eradication protocol, even when significant time (range 18 months to 9 years) had elapsed since initial isolation. In only one patient MRSA reappeared in the six-month follow-up period after the initial study period. Side-effects, like nausea, vomiting and diarrhoea were seen in five out of eleven patients, but did not lead to therapy cessation. CONCLUSION Chronic MRSA infection can be eradicated from respiratory tract samples using a six month dual antibiotic regimen and topical MRSA decolonization measures.

Evidence of an acinar response following treatment for exacerbation in adult patients with cystic fibrosis.

Background: Treating acute infectious exacerbations in cystic fibrosis (CF) patients with intravenous antibiotic therapy leads to variability in lung function and the ventilation distribution response. Part of the variable lung clearance index (LCI) response could be associated with the variable peripheral effects of intravenous antibiotic administration. Objectives: We explored to what extent the peripheral lung zones of CF patients could contribute to lung function improvements following treatment for infectious exacerbations. Methods: Over a 1-year period, 15 adult CF patients admitted for acute exacerbations were recruited. Lung function and multiple breath washout (MBW) tests were performed on the day of admission and at discharge. From the MBW test, we obtained acinar and conductive indices of ventilation heterogeneity and LCI. Results: The mean age (±SD) was 26 ± 5 years. Upon admission, the FEV1 was 54 ± 16% predicted and the LCI was 181 ± 26% predicted. After treatment, the average FEV1 increased to 61 ± 20% predicted (p < 0.001) and the LCI decreased to 173 ± 28% predicted (p = 0.042). The change in LCI was associated with a change in acinar (ρ = +0.54; p = 0.039) but not in conductive ventilation heterogeneity (p > 0.1). Conclusions: In CF patients in whom an improvement in LCI was obtained after treatment for an acute infectious exacerbation, this was paralleled by a decrease in acinar ventilation heterogeneity.

The quantitative link of lung clearance index to bronchial segments affected by bronchiectasis

In adult patients with cystic fibrosis (CF), the lung clearance index (LCI) derived from the multiple breath washout relates to both acinar and conductive ventilation heterogeneity. The latter component predicts an association between LCI and the number of bronchial segments affected by bronchiectasis. Here, we experimentally demonstrated this association in patients with CF, and also examined an ancillary group of patients with non-CF bronchiectasis. We conclude that lung disease severity in terms of number of bronchial segments results in an associated LCI increase, likely constituting a portion of LCI that cannot be reversed by treatment in patients with CF lung disease.

Evidence of Improved Small Airways Function after Azithromycin Treatment in Diffuse Panbronchiolitis

A 67-year-old never-smoker was diagnosed with diffuse panbronchiolitis (DPB) and was started on 250 mg azithromycin twice weekly. Over a 16-month observation period, lung function was assessed monthly, including a dedicated small airways test, the multiple breath nitrogen washout (MBW) with indices Scond and Sacin of ventilation heterogeneity at the level of the conductive and acinar air spaces, respectively. Baseline measurements indicated moderate airway obstruction, air trapping and considerable dysfunction of the small airways around the acinar entrance. Treatment resulted in excellent symptomatic improvement paralleled by marked improvements in FEV1, FVC, RV/TLC, Scond and Sacin; by contrast, there were no consistent changes in FEF75 or TLCO. While improvements were such that Scond fell within normal limits after 5 months, Sacin remained abnormal even after 16 months of treatment. This suggests a distinct acinar structural abnormality in DPB that cannot be reversed by azithromycin.

Quality of Life and Patient Satisfaction After Video-Assisted Thoracic Sympathicolysis for Essential Hyperhidrosis: A Follow-Up of 138 Patients

OBJECTIVES Essential hyperhidrosis (EH) is defined as excessive functioning of the sudomotor sweat system. Definitive treatment of choice is video-assisted thoracoscopic sympathetic interruption. Success rates are high, but compensatory hyperhidrosis (CH) remains a troublesome side effect. The aim of this study was to document patient satisfaction and side effects at least 6 months after thoracoscopic sympathicolysis. METHODS Between 2001 and 2005, 246 patients underwent bilateral ablation of the sympathetic chain at the thoracic level T2, T3, and/or T4. Questionnaires using open questions and scoring systems were sent at least 6 months after procedure and were returned by 138 patients (56%). RESULTS From the 138 patients (56 males/82 females), 39 suffered from cranial (±facial blushing), 34 from palmar, and 34 from axillary hyperhidrosis. Thirty-one patients were treated for a combination. No conversion to open surgery or deaths occurred. For the whole group, average quality of life was 4.5±2.5 before and 8.4±1.8 after surgery (P<.001). Ninety-one percent were very satisfied (score ≥7) and 80% showed an increased quality of life of ≥2. Compensatory sweating occurred in 76% of the patients, only 6% reported this as disabling. Comparing subgroups, a significant improvement in primary complaint score was found in 90%, 94%, and 91% for the T2, T3, and T4 patients, respectively. In the T4 group, the prevalence of CH was markedly lower (53%) and none of these patients were dissatisfied. CONCLUSION Thoracoscopic ablation of the sympathetic chain is an effective treatment for EH; CH occurs in the majority of patients, but only rarely impairs postoperative quality of life.

Whole-lung lavage: a successful treatment for restoring acinar ventilation distribution in primary acquired pulmonary alveolar proteinosis.

A 51-year-old active smoker with primary acquired pulmonary alveolar proteinosis (PAP) diagnosed by biopsy and anti-GM-CSF antibodies was treated safely with whole-lung lavage (WLL). This resulted in a rapid improvement of symptoms and arterial blood oxygenation, but not of standard lung function parameters. However, we also performed the multiple-breath nitrogen washout (MBW) test to determine the lung clearance index (LCI) as well as indices of acinar ventilation heterogeneity (Sacin) and conductive ventilation heterogeneity (Scond). At baseline, a distinct abnormality was seen for Sacin and LCI, while Scond was at the upper limit of normal for this subject. Sacin, in particular, was in excess of the Sacin abnormality corresponding to a 20-pack-year smoking history. Immediately after WLL, Sacin and Scond both fell to within a normal range while LCI also decreased but remained abnormal. The Sacin decrease was much greater than the Scond decrease, which was to be expected after 1 week of smoking cessation at the hospital (smoking was resumed after release from hospital). A follow-up visit 7 weeks after WLL revealed a spectacular improvement on CT scan and improvements in standard lung function. Another follow-up visit 14 weeks after WLL showed further improvements in standard lung function, and both Sacin and Scond remained well within the normal range, and LCI was above the upper limit of normal. We conclude that in this patient, removal of excess surfactant by WLL resulted in a restored ventilation distribution in most of the distal air spaces.

Increase in ventilated air spaces after eradication of chronic methicillin-resistant Staphylococcus aureus infection in cystic fibrosis patients

Abstract Effective microbiogical eradication of methicillin-resistant Staphylococcus aureus (MRSA) in patients with cystic fibrosis (CF) can be obtained, but its effect is not always clear-cut in terms of spirometric indices. The aim of this observational prospective cohort study was to study the potential effect of eradication of chronic MRSA infection on lung function including ventilation distribution. Six CF patients, chronically colonized with MRSA (median age: 21 years (range 14–46); median FEV1: 76 (95%CI 58–98)%pred) were successfully eradicated using oral rifampicin and fusidic acid in combination with topical decolonization measures. Lung function and multiple breath washout test were performed at the start and at the end of the eradication protocol and after an average follow-up period of 7·5±1·5(SD) months. One patient cultured MRSA again 4 months after successful eradication. All patients reported reduced sputum production and viscosity. By the end of the follow-up period, there was an increase in ventilated FRCMBW and no change in plethysmographic FRCPL. This resulted in a significant decrease of trapped air by half a litre (from 579 to 40 ml; P = 0·013). Lung clearance index (LCI) also showed a small but significant decrease (from 7·2 to 6·7; P = 0·014) after eradication of MRSA. We conclude that MRSA eradication can be successful, also in terms of recruitment of previously unventilated air spaces, potentially due to reduced sputum production and/or viscosity.