Respiratory physiology & neurobiology
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Respir Physiol Neurobiol · Oct 2014
Laryngeal narrowing during nasal ventilation does not originate from bronchopulmonary C-fibers.
We previously showed that nasal pressure support ventilation (nPSV) can lead to active inspiratory laryngeal narrowing, which originates from the stimulation of bronchopulmonary receptors. Among the three major types of bronchopulmonary receptors, which are variably stimulated by lung distension, C-fiber endings are remarkable, given that their stimulation can also trigger laryngeal closure. Taking advantage of our lamb model with blocked C-fibers, we aimed to assess whether bronchopulmonary C-fiber endings are involved in the active inspiratory laryngeal narrowing during nPSV. ⋯ Forty-eight hours later, two polysomnographic recordings were performed during nPSV 15/4 cmH2O, before and after C-fiber blockade. During nPSV, blockade of C-fibers did not prevent inspiratory EaTA (present for 74±41% of respiratory cycles vs. 64±35%, p=0.9). We conclude that active inspiratory laryngeal narrowing during nPSV does not originate from bronchopulmonary C-fiber endings.
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Respir Physiol Neurobiol · Oct 2014
Randomized Controlled TrialFlow Controlled Expiration is perceived as less uncomfortable than positive end expiratory pressure.
Recently, we presented Flow Controlled Expiration (FLEX) as a new option for lung-protective ventilation. FLEX delays the expiratory volume decrease in the lungs without prolonging the duration of expiration. Most ventilated patients nowadays receive spontaneous breathing support. ⋯ Only in forced choice comparison a stronger FLEX condition was perceived as less comfortable (p<0.01) than a weaker one. We conclude that FLEX decreases the breathing comfort in healthy subjects to a lesser extent than PEEP. Therefore, FLEX might be used to support ventilation therapy in spontaneously breathing patients.
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Respir Physiol Neurobiol · Sep 2014
Regional distribution of lung compliance by image analysis of computed tomograms.
Computed tomography (CT) can yield quantitative information about volume distribution in the lung. By combining information provided by CT and respiratory mechanics, this study aims at quantifying regional lung compliance (CL) and its distribution and homogeneity in mechanically ventilated pigs. The animals underwent inspiratory hold maneuvers at 12 lung volumes with simultaneous CT exposure at two end-expiratory pressure levels and before and after acute lung injury (ALI) by oleic acid administration. ⋯ A remarkably heterogeneous distribution of voxel compliance was found in the injured lungs. As the lung inflation increased, the homogeneity increased in healthy lungs but decreased in injured lungs. Image analysis brought novel findings regarding spatial homogeneity of compliance, which increases in ALI but not in healthy lungs by applying PEEP after a recruitment maneuver.
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Respir Physiol Neurobiol · Aug 2014
Clinical TrialExercise training improves breathing strategy and performance during the six-minute walk test in obese adolescents.
We aimed to examine ventilatory responses during the six-minute walk test in healthy-weight and obese adolescents before and after exercise training. ⋯ Our results suggest that exercise training can improve breathing strategy during submaximal exercise in obese adolescents and that this increase is associated with greater exercise performance.
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Respir Physiol Neurobiol · Aug 2014
Methylxanthine reversal of opioid-induced respiratory depression in the neonatal rat: mechanism and location of action.
Methylxanthines like caffeine and theophylline have long been used to treat apnea of prematurity. Despite their success in stimulating neonatal breathing, their mechanism of action remains poorly understood. ⋯ Here we used the in situ neonatal rat working heart-brainstem preparation and the ex vivo neonatal rat carotid body preparation to test the hypothesis that methylxanthines act at the level of the carotid body. We conclude that although the neonatal carotid body has active adenosine receptors, the effects of methylxanthine therapy are likely mediated centrally, predominantly via inhibition of cAMP-dependent phosphodiesterase-4.