Journal of breath research
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Chronic cough is one of the most common clinical problems and it may be secondary to different stimuli and diseases, including low-level physical and chemical stimulation of the esophageal-bronchial reflex, suggestive of cough-reflex hyperresponsiveness, in patients with gastroesophageal reflux; however, it is still debated whether gastroesophageal reflux could induce airway inflammation and acidification. The aim of this study was to investigate airway pH and cysteynil-leukotrienes (Cys-LTs) concentration (a marker of airway inflammation) in exhaled breath condensate (EBC). Patients with chronic cough and for which all known causes, excluding gastroesophageal reflux, had been investigated and ruled out, were enrolled in the study. ⋯ Forty-five patients were included in the study and those with gastroesophageal reflux had significantly lower EBC-pH and higher concentration of EBC-Cys-LTs. There was a linear inverse correlation between EBC-pH values and EBC-Cys-LTs logarithmically transformed, and a multivariate analysis confirmed that the only significant determinat variable of EBC-Cys-LTs was the presence of gastroesophageal reflux. This study adds knowledge on possible mechanisms related to chronic cough associated with gastroesophageal reflux, which seems to be strictly dependent on airway acidification and the production of Cys-LTs, therefore suggesting an underlying neurogenic inflammation with tachykinins involvement.
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Recent studies in spontaneously breathing subjects indicate the possibility of obtaining the alveolar fraction of exhaled breath condensate (aEBC). In critically ill mechanically ventilated patients, in whom microbial colonization of the upper airways is constant, collection of aEBC could considerably add to the ability of monitoring alveolar inflammation. We designed this study to test the feasibility of collecting aEBC in mechanically ventilated critically ill patients through a dedicated apparatus, i.e. a CO2 valve combined with a condenser placed in the expiratory limb of the ventilator circuit. ⋯ H2O2 was higher in patients with ARDS, compared to controls (0.09 (0.06-0.12) μM versus 0.03 (0.01-0.09) μM, p = 0.043), while no difference was found in proteins content, 8-isoprostane, 4-hydroxy-2-nonhenal. In conclusion, we demonstrate, in patients receiving controlled mechanical ventilation, that aEBC collection is feasible without detrimental effects on ventilator functioning, respiratory mechanics and gas exchange. In addition, we show that the sample obtained is appropriate for compounds analysis.
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Exhaled breath condensate (EBC) pH serves as a surrogate marker of airway lining fluid (ALF) pH and can be used to evaluate airway acidification (AA). AA is known to be present in acute respiratory distress syndrome (ARDS) and can be evaluated via continuous EBC pH measurement during mechanical ventilation. Lung recruitment maneuvers (LRMs) are utilized in the treatment of ARDS, however, their impact on EBC pH has never been explored. ⋯ Average EBC pH differed between phases and decreased after LRM (p = 0.001). EBC pH is affected by LRMs. EBC acidification following LRMs may represent a washout effect of opening acidic lung units and ventilating them or acute AA resulting from LRM.
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Randomized Controlled Trial
Effects of different ventilation strategies on exhaled nitric oxide in geriatric abdominal surgery.
Exhaled nitric oxide (eNO) has been suggested to be a marker of small airway injury. We investigated the effects of different ventilation strategies on eNO. Sixty-nine patients who received elective open abdominal surgery under general anesthesia with more than 2 h of surgery duration were randomly divided into three groups: high tidal volume of 10-12 ml kg(-1) predicted body weight (PBW) with zero end-expiratory pressure (ZEEP) (high VT + ZEEP group); low tidal volume of 6-8 ml kg(-1) PBW with 8 cm H2O positive end-expiratory pressure (PEEP) (low VT + PEEP group); and low tidal volume of 6-8 ml kg(-1) PBW with 8 cm H2O PEEP and recruitment maneuvers (low VT + PEEP + RMs group). eNO, respiratory system compliance (Crs), oxygenation index, inflammatory mediators tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β), IL-8, prostaglandin E2 (PGE2) and PGF2a as well as pulmonary function were measured during the perioperative period. ⋯ The Crs level in the high VT + ZEEP group significantly decreased with time but significantly increased in the low VT + PEEP + RMs group (P < 0.05). The oxygenation index, inflammatory mediators and pulmonary function did not statistically differ among the three groups. Compared with the low VT + PEEP + RMs group, the decreasing rate of postoperative eNO in the high VT + ZEEP and low VT + PEEP groups was higher, which may imply small airway injury during geriatric abdominal surgery.
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Based on the adsorption of analytes in the sampling loop, a time-resolved dynamic dilution introduction method was developed for negative ion mobility spectrometry to continuously monitor end-tidal propofol without other sample pre-separation. The dynamic dilution characteristics of propofol and moisture in the Teflon sample loop (4 mm o.d. and 2.4 mm i.d., 150 cm length) were both theoretically and experimentally investigated. ⋯ At the optimized carrier gas flow rate of 700 mL min(-1), the linear response range for propofol was achieved to be 0.2 to 20 ppbv with a limit of detection (LOD) of 65 pptv. Finally, this method was performed on a patient undergoing mastectomy surgery to continuously monitor the end-tidal propofol with an interval of five respirations and the result nicely demonstrated its fast response to the propofol changes.