Biomedical subjects

Capucine Morélot-Panzini

Publications and source records attributed to Capucine Morélot-Panzini.

3 recordsLinked to original sources

PubMed2006

Inspiratory resistances facilitate the diaphragm response to transcranial stimulation in humans.

BACKGROUND: Breathing in humans is dually controlled for metabolic (brainstem commands) and behavioral purposes (suprapontine commands) with reciprocal modulation through spinal integration. Whereas the ventilatory response to chemical stimuli arises from the brainstem, the compensation of mechanical loads in awake humans is thought to involve suprapontine mechanisms. The aim of this study was to test this hypothesis by examining the effects of inspiratory resistive loading on the response of the diaphragm to transcranial magnetic stimulation. RESULTS: Six healthy volunteers breathed room air without load (R0) and then against inspiratory resistances (5 and 20 cmH2O/L/s, R5 and R20). Ventilatory variables were recorded. Transcranial magnetic stimulation (TMS) was performed during early inspiration (I) or late expiration (E), giving rise to motor evoked potentials (MEPs) in the diaphragm (Di) and abductor pollicis brevis (APB). Breathing frequency significantly decreased during R20 without any other change. Resistive breathing had no effect on the amplitude of Di MEPs, but shortened their latency (R20: -0.903 ms, p = 0.03) when TMS was superimposed on inspiration. There was no change in APB MEPs. CONCLUSION: Inspiratory resistive breathing facilitates the diaphragm response to TMS while it does not increase the automatic drive to breathe. We interpret these findings as a neurophysiological substratum of the suprapontine nature of inspiratory load compensation in awake humans.

Airway Resistance↗

PubMed2006

Dyspnea as a noxious sensation: inspiratory threshold loading may trigger diffuse noxious inhibitory controls in humans.

Dyspnea, a leading respiratory symptom, shares many clinical, physiological, and psychological features with pain. Both activate similar brain areas. The neural mechanisms of dyspnea are less well described than those of pain. The present research tested the hypothesis of common pathways between the two sensations. Six healthy men (age 30-40 yr) were studied. The spinal nociceptive flexion reflex (RIII) was first established in response to electrical sural stimulation. Dyspnea was then induced through inspiratory threshold loading, forcing the subjects to develop 70% of their maximal inspiratory pressure to inhale. This led to progressive inhibition of the RIII reflex that reached 50 +/- 12% during the fifth minute of loading (P < 0.001), was correlated to the intensity of the self-evaluated respiratory discomfort, and had recovered 5 min after removal of the load. The myotatic H-reflex was not inhibited by inspiratory loading, arguing against postsynaptic alpha motoneuron inhibition. Dyspnea, like pain, thus induced counterirritation, possibly indicating a C-fiber stimulation and activation of diffuse noxious inhibitory descending controls known to project onto spinal dorsal horn wide dynamic range neurons. This confirms the noxious nature of certain types of breathlessness, thus opening new physiological and perhaps therapeutic perspectives.

Adult↗

PubMed2003

Simplified method to measure respiratory-related changes in arterial pulse pressure in patients receiving mechanical ventilation.

STUDY OBJECTIVES: Measuring respiratory-related changes in arterial pulse pressure is useful to guide fluid expansion in hemodynamically compromised patients. In the absence of automation, this can be uneasy in clinical practice. The objective of this study was to test an alternative approach (expiratory pause) that should be easier to apply. DESIGN: Prospective observational study comparing two measurement methods of a biological variable. PATIENTS: Seventeen patients receiving mechanical ventilation without spontaneous respiratory activity, with an arterial indwelling catheter, exhibiting respiratory-related fluctuations in arterial pressure. SETTING: Ten-bed respiratory ICU in a 2,000-bed university hospital. INTERVENTION: Analysis of clinically gathered data without specific experimental intervention. MEASUREMENTS: Determinations of the change in arterial pulse pressure observed during ventilatory cycling (Delta Pp,dyn) ["dynamic"] and change in arterial pulse pressure observed during expiratory pauses (Delta Pp,stat) ["static"] were performed to assess respiratory mechanics, and comparison of the two sets of data (correlation, Bland and Altman, Passing and Bablok regression). RESULTS: Delta Pp,dyn and Delta Pp,stat were strongly correlated (R = 0.964; 95% confidence interval, 0.917 to 0.987; p < 0.0001), with a good level of agreement (mean difference, 0.016; lower limit of agreement, - 0.087; upper limit, 0.120) and no systematic difference. CONCLUSION: Measuring respiratory-related Delta Pp,stat provides data that seem interchangeable with Delta Pp,dyn, providing an easy means to routinely obtain this information.

Adult↗