The neuropeptide somatostatin is involved in many functions in the central nervous system as well as in the periphery. When it is centrally injected, an irreversible apnea is often developed. In the present review, we discuss the effects of somatostatin as the result of its actions at three levels of the respiratory neural network: a) by modulating the output of cranial or spinal motoneurons; b...

Periodic breathing is a regularly recurring waxing and waning of tidal volume due to oscillations in central respiratory drive. It is a sign of respiratory control system instability. Under normal conditions, the respiratory and circulatory systems work in concert to deliver O2 according to metabolic demands, and to excrete CO2 to maintain acid-base homeostasis. As a result, arterial PO2 (PaO2)...

The human respiratory neural drive has an automatic component (bulbospinal pathway) and a volitional component (corticospinal pathway). The aim of this study was to assess the effects of a hypercapnia-induced increase in the automatic respiratory drive on the function of the diaphragmatic corticospinal pathway as independently as possible of any other influence. Thirteen healthy volunteers brea...

The problem concerning the nature and the function of the dead space is of basic importance for the full comprehension of the respiratory physiology and pathophysiology. To study the effect of an imposed external dead space on the optimal respiratory control system, we simulated the optimal neuro-muscular drive and respiratory signals, including instantaneous airflow and lung volume profiles, w...

It is not known whether nasal occlusion produces obstructive sleep apnea (OSA) by decreasing upper airway muscle activation via nasal reflexes or by increasing upper airway resistance and hence lowering the pressure in the pharnyx. The purpose of this study was to determine the effect of nasal occlusion on upper airway muscle activation. We studied seven men and measured alae nasi (AN) and geni...

this paper develops new results on the use of model predictive control to regulate the attitude of a ground station antenna. two degree of freedom az-el pedestal is considered as ground station antenna. permanent magnet synchronous motors are taken into consideration as the best choice for satisfaction of control objectives as actuators. the design is based on a two cascade controller consist o...

Opioids provide powerful analgesia but also efficacy-limiting adverse effects, including severe nausea, vomiting, and respiratory depression, by activating l-opioid receptors. Preclinical models suggest that differential activation of signaling pathways downstream of these receptors dissociates analgesia from adverse effects; however, this has not yet translated to a treatment with an improved ...

McKenzie DK, Butler JE, Gandevia SC. Respiratory muscle function and activation in chronic obstructive pulmonary disease. J Appl Physiol 107: 621–629, 2009. First published April 23, 2009; doi:10.1152/japplphysiol.00163.2009.— Inspiratory muscles are uniquely adapted for endurance, but their function is compromised in chronic obstructive pulmonary disease (COPD) due to increased loads, reduced ...

McKenzie DK, Butler JE, Gandevia SC. Respiratory muscle function and activation in chronic obstructive pulmonary disease. J Appl Physiol 107: 621–629, 2009. First published April 23, 2009; doi:10.1152/japplphysiol.00163.2009.— Inspiratory muscles are uniquely adapted for endurance, but their function is compromised in chronic obstructive pulmonary disease (COPD) due to increased loads, reduced ...

BACKGROUND The ventilatory capacity of the respiratory neuromuscular system can be studied with the hypercapnia test. OBJECTIVE To determine whether decreased response to the hypercapnia test is associated with failure to pass a spontaneous breathing trial (SBT) or extubation failure. METHODS We studied 103 intubated patients ready for SBT. We used a hypercapnia test in which we approximate...