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Respiratory Frequency (respiratory + frequency)
Selected AbstractsNon-contrast-enhanced perfusion and ventilation assessment of the human lung by means of fourier decomposition in proton MRIMAGNETIC RESONANCE IN MEDICINE, Issue 3 2009Grzegorz Bauman Abstract Assessment of regional lung perfusion and ventilation has significant clinical value for the diagnosis and follow-up of pulmonary diseases. In this work a new method of non-contrast-enhanced functional lung MRI (not dependent on intravenous or inhalative contrast agents) is proposed. A two-dimensional (2D) true fast imaging with steady precession (TrueFISP) pulse sequence (TR/TE = 1.9 ms/0.8 ms, acquisition time [TA] = 112 ms/image) was implemented on a 1.5T whole-body MR scanner. The imaging protocol comprised sets of 198 lung images acquired with an imaging rate of 3.33 images/s in coronal and sagittal view. No electrocardiogram (ECG) or respiratory triggering was used. A nonrigid image registration algorithm was applied to compensate for respiratory motion. Rapid data acquisition allowed observing intensity changes in corresponding lung areas with respect to the cardiac and respiratory frequencies. After a Fourier analysis along the time domain, two spectral lines corresponding to both frequencies were used to calculate the perfusion- and ventilation-weighted images. The described method was applied in preliminary studies on volunteers and patients showing clinical relevance to obtain non-contrast-enhanced perfusion and ventilation data. Magn Reson Med, 2009. © 2009 Wiley-Liss, Inc. [source] Body composition in young Standardbreds in training: relationships to body condition score, physiological and locomotor variables during exerciseEQUINE VETERINARY JOURNAL, Issue S36 2006C. LELEU Summary Reasons for performing study: Body composition is an essential factor in athletic performance of human sprinters and long distance runners. However, in horses, many questions remain concerning relationships between body composition and performance in the different equine activities. Objectives: To determine relationships between body composition, body score, physiological and locomotor variables in a population of young Standardbreds in training. Methods: Twenty-four 2-year-old Standardbreds were studied, body condition on a scale 0,5 and bodyweight recorded, and height at withers measured. Percentage of fat (%F), fat mass (FM) and fat free mass (FFM) were estimated echographically. During a standardised exercise test on the track, velocity, heart rate, respiratory frequency and blood lactate concentrations were measured. V4 and V200 (velocity for a blood lactate concentration of 4 mmol/1 and velocity of 200 beats/min) calculated. Basic gait variables were measured at 3 different speeds with an accelerometric device. Results: Body composition variables: %F and FM were significantly related to body condition score and physiological variables. Body score was highly correlated to %F (r=0.64) and FM (r = 0.71). V4 was negatively correlated to %V (r=-0.59) and FM (r = -0.60), P<0.05. V200 was also negatively related to %F and FM, (r=-0.39 and r = -0.37, respectively, P<0.1). No relationships were found between body composition and gait characteristics. Conclusions: Body composition was closely related to indirect measurements of aerobic capacity, which is a major factor of athletic performance in middle distance running horses. Potential relevance: As in human athletes, trainers should take special note to evaluate optimal bodyweight and body composition of race horses to optimise performance. [source] Effects of stylopharyngeus muscle dysfunction on the nasopharynx in exercising horsesEQUINE VETERINARY JOURNAL, Issue 4 2004C. TESSIER Summary Reasons for performing study: Nasopharyngeal collapse has been observed in horses as a potential cause of exercise intolerance and upper respiratory noise. No treatment is currently available and affected horses are often retired from performance. Objective: To determine the effect of bilateral glossopharyngeal nerve block and stylopharyngeus muscle dysfunction on nasopharyngeal function and airway pressures in exercising horses. Methods: Endoscopic examinations were performed on horses at rest and while running on a treadmill at speeds corresponding to HRmax50, HRmax75 and HRmax, with upper airway pressures measured with and without bilateral glossopharyngeal nerve block. Results: Bilateral glossopharyngeal nerve block caused stylopharyngeus muscle dysfunction and dorsal nasopharyngeal collapse in all horses. Peak inspiratory upper airway pressure was significantly (P = 0.0069) more negative at all speeds and respiratory frequency was lower (P = 0.017) in horses with bilateral glossopharyngeal nerve block and stylopharyngeus muscle dysfunction compared to control values. Conclusions: Bilateral glossopharyngeal nerve anaesthesia produced stylopharyngeus muscle dysfunction, dorsal pharyngeal collapse and airway obstruction in all horses. Potential relevance: The stylopharyngeus muscle is probably an important nasopharyngeal dilating muscle in horses and dysfunction of this muscle may be implicated in clinical cases of dorsal nasopharyngeal collapse. Before this information can be clinically useful, further research on the possible aetiology of stylopharyngeus dysfunction and dysfunction of other muscles that dilate the dorsal and lateral walls of the nasopharynx in horses is needed. [source] Respiratory responses evoked by blockades of ionotropic glutamate receptors within the Bötzinger complex and the pre-Bötzinger complex of the rabbitEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2005Donatella Mutolo Abstract The respiratory role of excitatory amino acid (EAA) receptors within the Bötzinger complex (BötC) and the pre-Bötzinger complex (pre-BötC) was investigated in ,-chloralose,urethane anaesthetized, vagotomized, paralysed and artificially ventilated rabbits by using bilateral microinjections (30,50 nL) of EAA receptor antagonists. Blockade of both N -methyl- d -aspartic acid (NMDA) and non-NMDA receptors by 50 mm kynurenic acid (KYN) within the BötC induced a pattern of breathing characterized by low-amplitude, high-frequency irregular oscillations superimposed on tonic phrenic activity and successively the disappearance of respiratory rhythmicity in the presence of intense tonic inspiratory discharges (tonic apnea). KYN microinjections into the pre-BötC caused similar respiratory responses that, however, never led to tonic apnea. Blockade of NMDA receptors by D(,)-2-amino-5-phosphonopentanoic acid (D-AP5; 1, 10 and 20 mm) within the BötC induced increases in respiratory frequency and decreases in peak phrenic amplitude; the highest concentrations caused tonic apnea insensitive to chemical stimuli. Blockade of non-NMDA receptors by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX; 1, 10 and 20 mm) within the BötC produced only less pronounced increases in respiratory frequency. Responses to D-AP5 in the pre-BötC were similar, although less pronounced than those elicited in the BötC and never characterized by tonic apnea. In the same region, CNQX provoked increases in respiratory frequency similar to those elicited in the BötC, associated with slight reductions in peak phrenic activity. The results show that EAA receptors within the investigated medullary subregions mediate a potent control on both the intensity and frequency of inspiratory activity, with a major role played by NMDA receptors. [source] Odor processing in multiple chemical sensitivityHUMAN BRAIN MAPPING, Issue 3 2007Lena Hillert Abstract Multiple chemical sensitivity (MCS) is characterized by somatic distress upon exposure to odors. As in other idiopathic environmental intolerances, the mechanisms behind the reported hypersensitivity are unknown. Using the advantage of the well-defined trigger (odor), we investigated whether subjects with MCS could have an increased odor-signal response in the odor-processing neuronal circuits. Positron emission tomography (PET) activation studies with several different odorants were carried out in 12 MCS females and 12 female controls. Activation was defined as a significant increase in regional cerebral blood flow (rCBF) during smelling of the respective odorant compared to smelling of odorless air. The study also included online measurements of respiratory frequency and amplitude and heart rate variations by recording of R wave intervals (RR) on the surface electrocardiogram. The MCS subjects activated odor-processing brain regions less than controls, despite the reported, and physiologically indicated (decreased RR interval) distress. In parallel, they showed an odorant-related increase in activation of the anterior cingulate cortex and cuneus-precuneus. Notably, the baseline rCBF was normal. Thus, the abnormal patterns were observed only in response to odor signals. Subjects with MCS process odors differently from controls, however, without signs of neuronal sensitization. One possible explanation for the observed pattern of activation in MCS is a top-down regulation of odor-response via cingulate cortex. Hum. Brain Mapp, 2007. © 2006 Wiley-Liss, Inc. [source] Unchanged heart rate,respiratory frequency ratio in preterm infants during spontaneous arousalsACTA PAEDIATRICA, Issue 1 2009Heinz Zotter Abstract Aim: To find out whether a correlation of heart rate (HR) and respiratory frequency (RF) defined as HR-RF-ratio (HRR) may be helpful to identify arousals in term and preterm infants. Methods: Polygraphic recordings were performed in 25 term infants (gestational age 40.1 ± 1.1 weeks) and 25 preterm infants (gestational age 31.1 ± 1.3 weeks) during undisturbed daytime sleep. Arousals were scored as suggested by the ,International Paediatric Work Group on Arousals' and divided into cortical arousals and subcortical arousals. HRR was defined as HR over RF. Arousals were compared to a 30-sec period preceding an arousals. Results: Two hundred arousals were scored (100 cortical arousals and 100 subcortical arousals). HRR increased during arousals in term infants (p < 0.001). This was true for cortical arousals (p < 0.001) and subcortical arousals (p < 0.05) of term infants. In contrast, in preterm infants HRR remained unchanged during cortical arousals and subcortical arousals. Conclusion: An increase of HRR during arousals is a simple parameter to identify arousals in term infants, but not in preterm infants suggesting that an unchanged HRR might be an indicator of an immature arousal response. [source] Does bladder voiding during sleep and wakefulness change the behavioural state of infants?ACTA PAEDIATRICA, Issue 12 2006HEINZ ZOTTER Abstract Aim: To evaluate whether bladder voiding in healthy infants is accompanied by body movements or any changes in heart rate (HR), respiratory frequency (RF) or electroencephalogram (EEG) frequency during sleep and during wakefulness. Methods: Polygraphic recordings were performed on 33 healthy infants (17 female) born at term. The infants' age at study entry was 41±10 d, and actual body weight was 4876±403 g (mean±SD). Bladder voiding was recorded by an adapted enuresis detector connected to the polygraphic computer unit. Results: Awakening was observed in 12 (36%) infants 77±9 s before bladder voiding. Twenty-one infants (64%) continued sleeping during bladder voiding. In sleeping infants, bladder voiding occurred during non-REM sleep only, and was accompanied by a cortical arousal. During wakefulness, RF was lower, and HR and EEG frequency were higher, but stayed constant during bladder voiding. Conclusion: Our observations demonstrate that bladder voiding in healthy infants during sleep is accompanied by body movements and changes in HR and EEG frequency, indicating cortical arousals, whereas during wakefulness these changes cannot be observed. [source] Cardiorespiratory effects of warm water immersion in elderly patients with chronic heart failureCLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 6 2005Åsa Cider Summary Background:, Hydrotherapy might be included in the rehabilitation of patients with chronic heart failure (CHF), but little is known about the acute cardiorespiratory reaction in warm water. The aim of this study was to assess the acute cardiorespiratory effect of immersion in warm water, in a clinical setting, in elderly patients with CHF compared with healthy age and sex matched persons. Methods:, Twelve patients (three females) with CHF, NYHA II,III, age 64 ± 6 years, and 12 healthy subjects were studied. Cardiorespiratory changes, on land and in a temperature-controlled swimming pool (33,34°C) were assessed during rest and exercise, in a sitting position, using continuous gas analyses. Results:, There were no significant differences, land versus water, in carbon dioxide production, total ventilation, respiratory frequency, respiratory exchange ratio, heart rate or blood pressure in either of the groups. A significant difference was found in oxygen uptake, at rest, land versus water in patients with CHF in comparison with healthy subjects (,0·2 ± 0·4 versus +0·3 ± 0·6 ml kg,1 min,1, P<0·01). Oxygen kinetics (,) increased significantly (P = 0·01) in both groups during exercise in water. Conclusion:, Hydrotherapy was well tolerated and the vast majority of the cardiorespiratory responses, during warm water immersion in a clinical setting, are similar in patients with CHF compared with healthy subjects. However, further larger studies, are needed to better understand the physiological reactions during hydrotherapy. [source] | |||||||||||||