The European respiratory journal : official journal of the European Society for Clinical Respiratory Physiology
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The aim of the study was to analyse the effects of positive end-expiratory pressure (PEEP) on volumetric capnography and respiratory system mechanics in mechanically ventilated patients. Eight normal subjects (control group), nine patients with moderate acute lung injury (ALI group) and eight patients with acute respiratory distress syndrome (ARDS group) were studied. Respiratory system mechanics, alveolar ejection volume as a fraction of tidal volume (VAE/VT), phase III slopes of expired CO2 beyond VAE and Bohr's dead space (VD/VT(Bohr)) at different levels of PEEP were measured. ⋯ PEEP had no effect on VAE/VT, expired CO2 slope beyond VAE and VD/VT(Bohr) in any group. A significant correlation (p<0.01) was found between VAE/VT and expired CO2 slope beyond VAE and lung injury score at zero PEEP. Indices of volumetric capnography are affected by the severity of the lung injury, but are unmodified by the application of positive end-expiratory pressure.
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Airway secretions are cleared by mucociliary clearance (MCC), in addition to other mechanisms such as cough, peristalsis, two-phase gas-liquid flow and alveolar clearance. MCC comprises the cephalad movement of mucus caused by the cilia lining the conducting airways until it can be swallowed or expectorated. MCC is a very complex process in which many variables are involved, all of which may modify the final outcome. ⋯ The underlying mechanism differs from one illness to another. Immotile cilia syndrome, asthma, bronchiectasis, chronic bronchitis, cystic fibrosis and some acute respiratory tract infections are among the most frequently reported. The present paper reviews normal mucociliary clearance and the effects of diseases on this process.
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Comparative Study
Validity of transcutaneous oxygen/carbon dioxide pressure measurement in the monitoring of mechanical ventilation in stable chronic respiratory failure.
The accuracy and precision of transcutaneous pressure measurements of oxygen (Ptc,O2) and carbon dioxide (Ptc,CO2) in the monitoring of nocturnal assisted ventilation in adult patients were evaluated. Transcutaneous measurements obtained with two analysers, Radiometer TINATCM3 (R) and Kontron MicroGas-7650 (K), were compared with arterial blood gases analysed in blood samples withdrawn simultaneously in 10 patients. Sensors were heated to 43 degrees C. ⋯ Mathematical correction of this bias neutralized the error in accuracy and improved the precision (SD of the differences transcutaneous blood gases - arterial blood gases). An additional correction, suppressing the between-subject scattering, improved the actual precision: precision was reduced from 1.9 to 0.8 kPa (14.4 to 5.7 mmHg) (R) and from 1.7 to 0.5 kPa (13.1 to 3.7 mmHg) (K) for oxygen, and from 1.0 kPa (7.8 mmHg) (R) and 0.7 kPa (5.6 mmHg) (K) to 0.4 kPa (3.2 mmHg) for carbon dioxide (R and K). In conclusion, with these two successive corrections, transcutaneous oxygen and carbon dioxide provide a reliable estimation of blood gases to monitor nocturnal ventilation in adults with chronic respiratory failure.
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The purpose of this study was to examine the additional diagnostic value of K-ras point mutations in the clinical diagnosis of peripheral lung tumours. To this end, bronchial wash fluids obtained during bronchoscopy from patients suspected of having lung cancer were studied. Only those patients were investigated for whom the cytological diagnosis was not conclusive for malignancy. ⋯ Analysis of bronchial wash fluids from 11 patients without lung cancer revealed no K-ras codon 12 mutations. In conclusion, K-ras point mutations can be identified in bronchial wash fluids obtained during bronchoscopic procedures. K-ras can be used as a biomarker in the clinical diagnosis of lung cancer and may serve as an adjunct to cytology in lung cancer diagnosis.
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The objective of this study was to determine the particle size and mass output of salbutamol from different nebulizers used under simulated breathing conditions. Seven nebulizer/compressor combinations were assessed. Each nebulizer was charged with 5 mg salbutamol solution and connected to a breathing simulator operating at tidal volumes of 150 mL and 600 mL. ⋯ The Intersurgical Cirrus nebulizer delivered the least salbutamol at both tidal volumes, although there was only a small difference between the Cirrus and Ventstream or Sidestream nebulizers at 150 mL tidal volume. The LC Plus nebulizer produced larger particles, mass median diameter 5.3 microm, compared with 3.6-4.0 microm for the other nebulizers. In conclusion, there were large differences in the delivery of salbutamol between the nebulizers studied, even between nebulizers of apparently the same class, and this should be borne in mind by regulatory authorities, clinicians and researchers.