Respiratory physiology & neurobiology
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Respir Physiol Neurobiol · Dec 2015
Simultaneous monitoring of intratidal compliance and resistance in mechanically ventilated piglets: A feasibility study in two different study groups.
Compliance measures the force counteracting parenchymal lung distension. In mechanical ventilation, intratidal compliance-volume (C(V))-profiles therefore change depending on PEEP, tidal volume (VT), and underlying mechanical lung properties. Resistance counteracts gas flow through the airways. ⋯ In the lavage group, a large drop in resistance at small volumes and slow decrease toward larger volumes was found for small PEEP/VT-settings where C(V)-profiles revealed a volume-dependent increase (small PEEP) or a decrease (large PEEP and large VT). R(V)-profiles depend characteristically on PEEP, VT, and possibly whether lungs are healthy or not. Curved R(V)-profiles might indicate pathological changes in the underlying mechanical lung properties and/or might be a sign of derecruitment.
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Respir Physiol Neurobiol · Jan 2019
Effects of two different ventilation strategies on respiratory mechanics during robotic-gynecological surgery.
It is unknown which is the best ventilatory approach in patients scheduled for gynecological robotic surgery in Deep Trendelenburg position in terms of respiratory mechanics. 40 patients were enrolled: 20 patients received a standard ventilation and 20 patients received a protective ventilation. Gas exchanges, respiratory mechanics and hemodynamic parameters were recorded. No significant differences were found between the two groups in terms of respiratory mechanics. ⋯ In both groups, a significant reduction of pH (p < 0.01) and a significant increase of PaCO2 (p < 0.01) were observed between Baseline and Extubation Time. At the Extubation time, PaCO2 was significantly higher during protective ventilation compared to standard ventilation. In this particular surgical setting, a protective ventilation strategy did not improve the respiratory mechanics compared to the standard ventilation strategy and was ineffective on post-operative gas exchanges.
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Respir Physiol Neurobiol · Aug 2018
Modelling nasal high flow therapy effects on upper airway resistance and resistive work of breathing.
The goal of this paper is to quantify upper airway resistance with and without nasal high flow (NHF) therapy. For adults, NHF therapy feeds 30-60 L/min of warm humidified air into the nose through short cannulas which do not seal the nostril. NHF therapy has been reported to increase airway pressure, increase tidal volume (Vt) and decrease respiratory rate (RR), but it is unclear how these findings affect the work done to overcome airway resistance to air flow during expiration. Also, there is little information on how the choice of nasal cannula size may affect work of breathing. In this paper, estimates of airway resistance without and with different NHF flow (applied via different cannula sizes) were made. The breathing efforts required to overcome airway resistance under these conditions were quantified. ⋯ NHF raises expiratory resistance but it can reduce the work required to overcome upper airway resistance via a fall in inspiratory work of breathing, RR and minute volume.
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Respir Physiol Neurobiol · Jun 2016
The role of the Kölliker-Fuse nuclei in the determination of abdominal motor output in a perfused brainstem preparation of juvenile rat.
The abdominal muscles are largely quiescent during normal breathing but may exhibit tonic activity or subtle respiratory modulation. The origin of baseline abdominal motor nerve activity (AbNA) if present remains uncharacterised. The contribution of the Kölliker-Fuse nucleus (KF) in the dorsolateral pons in the patterning and amplitude of AbNA was investigated using in situ perfused brainstem preparations of juvenile rats (n=12). ⋯ Interestingly, the type of AbNA exhibited correlated with postinspiratory duration. Targeted microinjections of GABA-A receptor agonist isoguvacine (10mM; 70nl) into KF however did not significantly modify pattern or amplitude of baseline AbNA in either Type besides the selective abolition of the postinspiratory phase and, consequently, postinspiratory modulation in AbNAwhen present. In sum, the KF is not a major contributorin setting baseline abdominal motor output.
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Respir Physiol Neurobiol · Jun 2017
The effect of sitting and calf activity on leg fluid and snoring.
Prolonged sitting may promote leg fluid retention that redistributes to the neck during sleep and contributes to snoring. This could be attenuated by calf activity while sitting. In 16 healthy non-obese subjects we measured leg fluid volume (LFV) below the knees using bioelectrical impedance while sitting for 4h, snoring using a portable BresoDx™ device, and Mallampati grade. ⋯ The effects of sitting±calf activity on LFV and snoring were compared. We found that LFV increased by 216±101.0ml (p<0.0001) after sitting. Calf activity while sitting attenuated LFV by 53.8ml (p<0.0001) and, in all five subjects with severe upper airway narrowing (Mallampati grade IV), reduced snoring duration (from 357±132.9 to 116.2±72.1s/h, p=0.02) suggesting reduced overnight rostral fluid shift to the neck.