Ching-Kai Lin

Work of breathing and respiratory drive in obesity

Obesity, particularly severe central obesity, affects respiratory physiology both at rest and during exercise. Reductions in expiratory reserve volume, functional residual capacity, respiratory system compliance and impaired respiratory system mechanics produce a restrictive ventilatory defect. Low functional residual capacity and reductions in expiratory reserve volume increase the risk of expiratory flow limitation and airway closure during quiet breathing. Consequently, obesity may cause expiratory flow limitation and the development of intrinsic positive end expiratory pressure, especially in the supine position. This increases the work of breathing by imposing a threshold load on the respiratory muscles leading to dyspnoea. Marked reductions in expiratory reserve volume may lead to ventilation distribution abnormalities, with closure of airways in the dependent zones of the lungs, inducing ventilation perfusion mismatch and gas exchange abnormalities. Obesity may also impair upper airway mechanical function and neuromuscular strength, and increase oxygen consumption, which in turn, increase the work of breathing and impair ventilatory drive. The combination of ventilatory impairment, excess CO2 production and reduced ventilatory drive predisposes obese individuals to obesity hypoventilation syndrome.

Evaluating pleural ADA, ADA2, IFN-γ and IGRA for diagnosing tuberculous pleurisy

OBJECTIVE Conventional methods for diagnosing tuberculous pleurisy (TB pleurisy) are either invasive or have a long turn-around-time. Performances of pleural adenosine deaminase (ADA), ADA2, interferon-gamma (IFN-γ), and interferon-gamma release assays (IGRA) as diagnostic tools for TB pleurisy were evaluated. METHODS Eighty-eight patients with lymphocyte-predominant pleural exudates between June 2010 and March 2011, including 31 with clinically diagnosed TB pleurisy, were prospectively studied. Pleural ADA and ADA2 activity were measured by colorimetric method, IFN-γ levels by enzyme-linked immuno-sorbent assay, and IGRA by enzyme-linked immuno-spot (T-SPOT.TB) assay. RESULTS Pleural ADA, ADA2, and IFN-γ levels, but not the proportion of positive T-SPOT.TB assay, were significantly higher in patients with TB pleurisy than in those without TB pleurisy. The area under the receiver-operating-characteristic (ROC) curve was 0.920, 0.893, 0.875, and 0.544 for IFN-γ, ADA2, ADA, and T-SPOT.TB assay, respectively. The combination of ADA ≥ 40 IU/L and IFN-γ ≥ 75 pg/mL yielded a specificity of 100%. CONCLUSIONS Pleural ADA, ADA2 and IFN-γ, but not T-SPOT.TB assay, are all sensitive and specific for TB pleurisy. In patients with lymphocyte-predominant pleural exudates, ADA ≥ 40 IU/L and IFN-γ ≥ 75 pg/mL in pleural effusion imply a very high probability of TB pleurisy.

Clinical characteristics of bacteraemia caused by Lactobacillus spp. and antimicrobial susceptibilities of the isolates at a medical centre in Taiwan, 2000–2014

The clinical characteristics of 89 patients with Lactobacillus bacteraemia treated at a university-affiliated hospital in northern Taiwan during 2000-2014 were retrospectively evaluated. Lactobacillus spp. were identified by 16S rRNA sequencing analysis and matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF/MS). Antimicrobial susceptibilities of the isolates were determined by broth microdilution. The most commonly isolated species was Lactobacillus salivarius (n = 21), followed by Lactobacillus paracasei (n = 16) and Lactobacillus fermentum (n = 13). Excluding three isolates with lower 16S rRNA sequence similarity, MALDI-TOF/MS provided correct identification for 84.9% (73/86) of Lactobacillus isolates. Concordant identification was lowest for Lactobacillus casei (11%). The main infection foci were intra-abdominal infection (49%) and catheter-related bloodstream infection (17%). Only one-half of the patients received adequate antibiotic treatment during the bacteraemic episode. The majority of patients with Lactobacillus bacteraemia were immunocompromised. The 7-day and in-hospital mortality rates were 21% and 62%, respectively, and underlying malignancy was associated with a higher in-hospital mortality rate (odds ratio = 2.666). There were no significant differences in mortality (7-day, 14-day, 30-day and in-hospital) among patients with bacteraemia due to different Lactobacillus spp. Minimum inhibitory concentrations were highest for glycopeptides, cephalosporins and fluoroquinolones and were lowest for carbapenems and aminopenicillins. Lactobacillus bacteraemia was associated with a high mortality rate, and patient outcome was associated with underlying malignancy. MALDI-TOF/MS was able to accurately identify 84.9% of the Lactobacillus isolates, and L. salivarius was the predominant pathogen. The accuracy rate for identification of Lactobacillus spp. by MALDI-TOF/MS was lowest for L. casei.

Plasma Biomarkers Can Predict Treatment Response in Tuberculosis Patients: A Prospective Observational Study.

AbstractDespite numerous studies, there has been little progress in the use of biomarkers for predicting treatment response in patients with tuberculosis (TB).Patients with culture-confirmed pulmonary TB between 2010 and 2014 were prospectively recruited. Blood samples were taken upon diagnosis and 2 months after the start of standard anti-TB treatment. A pilot study utilizing measurement of TB-antigen-stimulated cytokines was conducted to select potential biomarkers for further testing. Outcome was defined as persistent culture positivity at 2 months into treatment.Of 167 enrolled patients, 26 had persistent culture positivity. RANTES, IL-22, MMP-8, IL-18, MIG, and Granzyme A were selected as potential biomarkers. For predicting persistent culture positivity, receiver-operating characteristics (ROC) analysis showed that initial RANTES (AUC: 0.725 [0.624–0.827]) and 2-month MMP-8 (AUC: 0.632 [0.512–0.713]) had good discriminative ability. Using a logistic regression model, low initial RANTES level (<440 pg/mL), initial smear positivity, and high 2-month MMP-8 level (>3000 pg/mL) were associated with persistent culture positivity. Low initial RANTES level and initial smear positivity had a positive predictive value of 60% (12/20) for persistent culture positivity, compared with 4% (3/75) among patients with high RANTES level and smear negativity upon diagnosis. In the 72 patients with either low RANTES/smear negativity or high RANTES/smear positivity upon diagnosis, the 2-month MMP-8 level had a positive and negative predictive value of 24 and 94%, respectively, for 2-month culture status.Aside from an initial sputum smear status, serum RANTES level at diagnosis and MMP-8 level at 2 months of treatment may be used to stratify risk for culture persistence.

Factors associated with subsequent nontuberculous mycobacterial lung disease in patients with a single sputum isolate on initial examination

Very few studies have focused on the outcome and management of patients with a single sputum isolate of nontuberculous mycobacterium (NTM) on initial examination. Patients with a single isolate of Mycobacterium avium complex (MAC), M. chelonae-abscessus, M. kansasii, or M. fortuitum from at least three sputum samples collected within 1 month were retrospectively identified. Those with follow-up sputum samples within 1 year were included in the analysis. Among the 202 patients included, M. fortuitum (n = 71, 35.1%) and MAC (n = 70, 34.7%) were the most common NTM species isolated, followed by M. chelonae-abscessus (n = 40, 19.8%) and M. kansasii (n = 21, 10.4%). The mean clinical follow-up period was 26.2 months. Forty-four patients (21.8%) had subsequent positive cultures of the same NTM species, while eight (4.0%) had bronchiectasis and developed NTM lung disease (NTM-LD). Neither patients without bronchiectasis nor those with M. fortuitum subsequently developed NTM lung disease. Among bronchiectatic patients with NTM other than M. fortuitum, age ≤65 years (p 0.006, OR 32.13), malignancy (p 0.048, OR 14.35), and initial radiographic score >2 (p 0.027, OR 20.06) were associated with subsequent NTM-LD. In all of the NTM patients, bronchiectasis (p <0.001, OR 5.46) and age ≤65 years (p 0.002, OR 3.29) were significantly associated with subsequent positive NTM culture. In patients with a single isolation of NTM from respiratory specimens, the presence of bronchiectasis and younger age indicates higher risk of subsequent culture-positivity and NTM-LD. Single isolation of M. fortuitum is of little clinical significance. Other patients with NTM, younger age, and more severe radiographic pulmonary lesion also warrant further attention.

Compliance and barriers to implementing the sepsis resuscitation bundle for patients developing septic shock in the general medical wards

BACKGROUND/PURPOSE This two-part study aimed to investigate compliance with the sepsis resuscitation bundle (SRB) and the barriers to its implementation for patients developing septic shock in the general medical wards. METHODS In the first part, medical records of patients who were admitted to the intensive care unit from the general medical wards due to septic shock were reviewed. Compliance rates with the six SRB components were assessed. In the second part, responsible junior physicians (first-year and second-year residents) in the general wards and senior physicians (third-year residents and fellows) were randomly invited for questionnaire-based interviews. RESULTS In the first part, during the 6-month study period, 40 patients were included. Overall compliance with the SRB within 6 h was only 2.5%, mainly due to femoral catheterization (42.5%) and the lack of measuring central venous oxygen saturation (ScvO₂). Delayed completion of SRB components contributed little to the low compliance rate. In the second part, based on the questionnaire results of 71 junior physicians and 64 senior physicians, the junior physicians were less familiar with the SRB guidelines, particularly regarding the meaning of ScvO₂ (p = 0.01) and management of low ScvO₂ (p = 0.04). Junior physicians were also more reluctant to measure the central venous pressure (CVP; p = 0.04) and the ScvO₂ (p = 0.01), and were also less confident with internal jugular vein or subclavian vein catheterization (p < 0.001). CONCLUSION Compliance with the SRB for patients developing septic shock in the general medical wards is very low. Besides providing educational programs to improve awareness and acceptance of the SRB, measures to help in central venous catheterization and completion of SRB may be considered.

Effect of treatment by laser-assisted uvulopalatoplasty on cardiopulmonary exercise test in obstructive sleep apnea syndrome.

OBJECTIVES: To evaluate the effects of successful laser-assisted uvulopalatoplasty (LAUP) on cardiopulmonary exercise testing (CPET) in patients with obstructive sleep apnea syndrome (OSAS). STUDY DESIGN AND SETTING: Twenty-five subjects with moderately severe or severe OSAS who desired LAUP were enrolled. All patients had an overnight sleep study and CPET before and 3 months after LAUP. Patients were divided into 2 groups based on the success (group I) or failure (group II) of LAUP to improve their sleep apnea. RESULTS: Successful LAUP in group I was followed by improvement in right ventricular ejection fraction, maximal work rate (WRmax), VO2max/kg, anaerobic threshold, oxygen pulse, and a lower breathing reserve. CPET results were unchanged after LAUP in group II subjects. CONCLUSION: Patients with OSAS before LAUP had abnormal CPET as reflected by low VO2peak/kg, WRmax, anaerobic threshold, and oxygen pulse. All of these variables improved after LAUP that successfully ameliorated OSAS.

Learning curve and advantages of endobronchial ultrasound‐guided transbronchial needle aspiration as a first‐line diagnostic and staging procedure

Endobronchial ultrasound‐guided transbronchial needle aspiration (EBUS‐TBNA) is now the standard for mediastinal lymph node staging of lung cancer. Training and maintenance of technical skills is very important in order to apply new techniques in clinical use.

The value of radial endobronchial ultrasound-guided bronchial brushing in peripheral non-squamous non-small cell lung cancer

Radial endobronchial ultrasound (R-EBUS) is one important diagnostic approach in non-small cell lung cancers (NSCLC). However, the small samples obtained from R-EBUS-guided transbronchial biopsies are sometimes insufficient for pathological and molecular diagnosis. Herein, we investigated the suitability of R-EBUS-guided bronchial brushing specimens for NSCLC diagnosis and EGFR genotyping. We enrolled 941 consecutive patients with peripheral pulmonary lesions who underwent R-EBUS. Cytology-positive brushing specimens from non-squamous NSCLC patients were tested for EGFR mutations. Non-squamous NSCLC was diagnosed in 624 patients (66.3%). Positive cytology was documented in the brushing samples of 376 patients (60.3%). Higher diagnostic yields were obtained in patients exhibiting bronchus signs on chest tomography, and those with R-EBUS probe located within the lesion. EGFR genotyping was successfully performed in 363 samples (96.5% of cytology-positive brushing samples). EGFR genotyping concordance between brushing specimens and matched tissue samples was 88.7% (kappa = 0.745, P < 0.001). Furthermore, 144 non-squamous NSCLC patients (23.1%) with failed pathological diagnosis or EGER sequencing by R-EBUS-guided transbronchial biopsy required repeat biopsies. However, it was achieved successfully from the brushing specimens of 57 patients (39.6%). In conclusion, for patients with peripheral lung cancer, R-EBUS-guided bronchial brushing could provide an additional sampling method for diagnosis and EGFR genotyping.

Current advances of endobronchial ultrasonography in the diagnosis and staging of lung cancer

The diagnosis and staging of patients with lung cancer has relied on tissue sampling. Endobronchial ultrasound (EBUS) is a minimally invasive procedure for the rapid and safe acquisition of tissue and can be done easily and repeatedly. EBUS transbronchial needle aspiration (TBNA) is now the standard for diagnosis of mediastinal and hilar lymphadenopathy and should be considered in patients who have a high probability of lymph node metastases without systemic involvement. EBUS also provides guidance for biopsy of peripheral lung lesions. Recent advances of EBUS with new techniques help to improve the diagnostic yield and decrease the complication rate and total procedure time.