Respiratory physiology & neurobiology
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Respir Physiol Neurobiol · Jun 2020
Randomized Controlled TrialNasal high flow improves ventilation during propofol sedation: A randomized cross-over study in healthy volunteers.
Hypoventilation and carbon dioxide (CO2) retention are common during sedation. The current study investigated the ventilation responses to nasal high flow (NHF) during sedation with propofol. ⋯ During sedation with propofol, NHF without supplemental oxygen attenuated CO2 retention and reduced the respiratory rate. The findings show that NHF can improve ventilation during sedation, which may reduce the risk of complications related to hypoventilation.
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Respir Physiol Neurobiol · Jun 2020
Endogenous glutamatergic inputs to the Parabrachial Nucleus/Kölliker-Fuse Complex determine respiratory rate.
The Kölliker-Fuse Nucleus (KF) has been widely investigated for its contribution to "inspiratory off-switch" while more recent studies showed that activation of the Parabrachial Nucleus (PBN) shortened expiratory duration. This study used an adult, in vivo, decerebrate rabbit model to delineate the contribution of each site to inspiratory and expiratory duration through sequential block of glutamatergic excitation with the receptor antagonists 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo[f]quinoxaline-2,3-dione (NBQX) and d(-)-2-amino-5-phosphonopentanoic acid (AP5). ⋯ The contribution of PBN activity to inspiratory and expiratory duration was equal while block of the KF affected inspiratory duration more than expiratory. We conclude that in the in vivo preparation respiratory rate greatly depends on PBN/KF activity, which contributes to the "inspiratory on- "and "off-switch", but is of minor importance for the magnitude of phrenic motor output.
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Respir Physiol Neurobiol · Jun 2020
Evidence for the emergence of an opioid-resistant respiratory rhythm following fentanyl overdose.
Breathing resumes within one to two minutes following fentanyl overdose induced apnea in spontaneously breathing rats. As this regular rhythm is produced at a time wherein fentanyl concentrations and receptor occupancy are likely to be extremely high, the mechanisms initiating and sustaining such a respiratory activity remain unclear. Forty-four un-anesthetized adult rats were studied in an open-flow plethysmograph. ⋯ When a second injection of the highest dose of fentanyl (300 μg.kg-1) was performed at 10 min, ventilation was not significantly affected and no apnea was produced in major contrast to the first injection. When a similar injection was performed 30 min after the first injection, in a separate group of rats, an apnea and breathing depression was produced in 30 % of the animals, while in the other rats, ventilation was unaffected. We conclude that the depressed regular respiratory activity emerging during and following fentanyl overdose is uniquely resistant to fentanyl.