Lin Mc

Bilateral diaphragmatic paralysis--a rare cause of acute respiratory failure managed with nasal mask bilevel positive airway pressure (BiPAP) ventilation

A 68 yr old woman presented with acute respiratory failure. She was suspected of having a phrenic-diaphragmatic impairment, without evidence of an intrinsic lung disease or generalized neuromuscular disorder, after 3 weeks of prolonged mechanical ventilation. A series of studies, including fluoroscopy, phrenic nerve stimulation test and diaphragmatic electromyography, was performed before the diagnosis of bilateral diaphragmatic paralysis (BDP) was confirmed. The patient was successfully weaned from the conventional mechanical ventilator, and was placed on nasal mask bi-level positive airway pressure (BiPAP) ventilation. A high degree of clinical suspicion of bilateral diaphragmatic paralysis should always be raised in patients suffering respiratory failure without definite predisposing factors. Weaning with noninvasive nasal mask ventilation should be tried first instead of direct tracheostomy.

Wheezing, a significant clinical phenotype of COPD: experience from the Taiwan Obstructive Lung Disease Study.

Background COPD is an important public health challenge with significant heterogeneity of clinical presentation and disease progression. Clinicians have been trying to find phenotypes that may be linked to distinct prognoses and different therapeutic choices. Not all patients with COPD present with wheezing, a possible clinical phenotype that can help differentiate patient subgroups. Methods The Taiwan Obstructive Lung Disease study was a retrospective, multicenter research study to investigate the treatment patterns of COPD after the implementation of the Global Initiative for Chronic Obstructive Lung Disease 2011 guidelines. Between November 2012 and August 2013, medical records were retrieved from patients with COPD aged ≥40 years; patients diagnosed with asthma were excluded. Demographic data, lung function, symptom scores, and acute exacerbation were recorded and analyzed, and the differences between patients with and without wheezing were evaluated. Results Of the 1,096 patients with COPD, 424 (38.7%) had the wheezing phenotype. The wheezing group had significantly higher COPD Assessment Test scores (12.4±7.8 versus 10.5±6.7, P<0.001), higher modified Medical Research Council grade (2.0±1.0 versus 1.7±0.9, P<0.001), and more acute exacerbations within the past year (0.9±1.3 versus 0.4±0.9, P<0.001) than the nonwheezing group. The postbronchodilator forced expiratory volume in 1 second was lower in wheezing patients (1.2±0.5 L versus 1.5±0.6 L, P<0.001). Even in patients with maintenance treatment fitting the Global Initiative for Chronic Obstructive Lung Disease 2011 guidelines, the wheezing group still had worse symptom scores and more exacerbations. Conclusion Wheezing is an important phenotype in patients with COPD. Patients with COPD having the wheezing phenotype are associated with worse symptoms, more exacerbations, and worse lung function.

Oxygen, arterial blood gases and ventilation are unchanged during dialysis in patients receiving pressure support ventilation

This study was undertaken to observe whether dialysis-induced alveolar hypoventilation and arterial hypoxaemia occur during bicarbonate haemodialysis in patients receiving partial mechanical support with pressure support ventilation. Nineteen patients admitted to the medical intensive care unit requiring mechanical ventilation and haemodialysis were enrolled. Arterial blood gas, white blood cell (WBC) count, minute ventilation, respiratory rate, breathing pattern and blood pressure were measured according to the following time schedule: pre-dialysis (time 0), and at 15, 30, 60, 120, 180, 240 min thereafter. Results showed that, with the use of cuprammonium dialyser, the WBC count dropped immediately and reached the nadir 15 min after haemodialysis. Thereafter, it recovered and overshot the pre-dialysis values until the end of dialysis. The bicarbonate dialysate indeed resulted in rapid and significant metabolic alkalosis. However, no decrease of PaO2 occurred throughout haemodialysis. The tidal volume, minute ventilation and breathing pattern remained stable during haemodialysis. We conclude that neither dialysis-induced alveolar hypoventilation nor arterial hypoxaemia developed during bicarbonate dialysis in patients mechanically ventilated with the pressure support ventilation.

Factors associated with the prescription of inhaled corticosteroids in GOLD group A and B patients with COPD – subgroup analysis of the Taiwan obstructive lung disease cohort

Background and objective The overprescription of inhaled corticosteroids (ICS) in the current Global Initiative for Chronic Obstructive Lung Disease (GOLD) group A and B patients with chronic obstructive pulmonary disease (COPD) is not uncommon in clinical practice. The aim of this study was to explore the factors associated with the use of ICS in these patients. Methods The Taiwan obstructive lung disease (TOLD) study was a retrospective, observational nationwide survey of COPD patients conducted at 12 hospitals (n=1,096) in Taiwan. Multivariate logistic regression models were used to explore the predictors of ICS prescription in GOLD group A and B patients. Results Among the group A (n=179) and group B (n=398) patients, 198 (34.3%) were prescribed ICS (30.2% in group A and 36.2% in group B, respectively). The wheezing phenotype was present in 28.5% of group A and 34.2% of group B patients. Wheezing was the most significant factor for an ICS prescription in group A (odds ratio [OR], 2.33; 95% confidence interval [CI], 1.14–4.75; P=0.020), group B (OR, 1.93; 95% CI, 1.24–2.99; P=0.004), and overall (OR, 2.04; 95% CI, 1.40–2.96; P<0.001). The COPD assessment test score was also associated with an ICS prescription in group B (OR, 1.04; 95% CI, 1.00–1.07; P=0.038). Conclusion About one-third of the GOLD group A and B patients with COPD in Taiwan are prescribed ICS. Our findings suggest that wheezing and COPD assessment test score are related to the prescription of ICS in these patients.

Spontaneous variability of arterial oxygenation in critically ill mechanically ventilated patients.

Objective: To assess the magnitude of spontaneous variability of arterial oxygenation and oxygen tension-based indices over time in medical intensive care unit (ICU) patients and to study whether high positive end-expiratory pressure (PEEP) or inverse inspiratory-to-expiratory (I:E) ratio ventilation (IRV) results in a greater variability than low PEEP with conventiona l I:E ratio ventilation. Design: Prospective study. Setting: Medical ICU in a tertiary medical center. Participants: 23 patients requiring a pulmonary artery floating catheter for hemodynamic monitoring. Intervention: After being completely sedated, patients were randomized to receive pressure-control ventilation at setting A: high PEEP (15 cmH2O) with conventional I:E ratio (1:2) and setting B: inverse I:E ratio (2:1) with low PEEP (5 cmH2O) alternately, and then at setting C: low PEEP (5 cmH2O) with conventional I:E ratio (1:2). Each ventilation setting lasted 1 h. Measurements and results: The arterial and mixed venous blood samples were measured simultaneously at baseline (time 0), and at 15, 30, 45, and 60 min thereafter. The coefficient of variation (CV) of arterial oxygen tension (PaO2) over time was 5.9 % for setting A, 7.2 % for setting B, and 6.9 % for setting C. ANOVA showed no significant differences in CVs of PaO2 between the three settings. Oxygen tension-based indices, alveolar-arterial oxygen difference (A-aDO2) and PaO2/PAO2 (alveolar oxygen tension), displayed CV s equal to that of PaO2; the CV of A-aDO2/PaO2 was significantly greater than that of PaO2. Conclusions: In critically ill medical ICU patients, despite sedation, the spontaneous variability in PaO2 over time is substantial. A high PEEP or IRV does not contribute to the increased variation in PaO2.