OBJECTIVE To evaluate the effects of various levels of pressure support (PS) during noninvasive ventilation delivered through a helmet on breathing pattern, inspiratory effort, CO2 rebreathing, and comfort. DESIGN Physiologic study. SETTING University-affiliated hospital. PATIENTS AND PARTICIPANTS Eight healthy volunteers. INTERVENTIONS Volunteers received ventilation through a helmet w...

Alveolar macrophages (AM) may be exposed to a range of CO2 and pH levels depending on their location in the alveoli and the health of the lung. Cytokines produced by AM contribute to inflammation in acute lung injury (ALI). Current ventilatory practices for the management of ALI favour low tidal volumes, which can give rise to increases in CO2 and changes in pH of the alveolar microenvironment....

In their editorial, R. Naeije and P. van de Borne discuss the cause of exercise hyperventilation in PAH, as well as in patients with congestive heart failure, and attribute it mainly to an increased chemosensitivity on the basis of some previous inert gases studies. In fact, three factors determine the ventilatory response to exercise, 1) the CO2 production, 2) the ratio of physiological dead s...

background: the aim of this study was to prevent of increasing end tidal co2(et co 2) with changing of vital capacity and respiratory rate, when using of birthing filter in infants. materials and method: in a randomized clinical trial study, ninety four infant' patients were studied in three groups . basic values, such as: peak inspiratory pressure, tidal volume, minute ventilation, respiratory...

The effect on ventilation of airway anaesthesia, produced by the inhalation of a 5% bupivacaine aerosol (aerodynamic mass median diameter = 4.77 micron), was studied in 12 normal subjects. The dose and distribution of the aerosol were determined from lung scans after the addition to bupivacaine of 99mTc. Bupivacaine labelled in this way was deposited primarily in the central airways. The effect...

We have studied 14 female patients undergoing elective laparoscopy under general anaesthesia with peritoneal insufflation of carbon dioxide in order to examine changes in physiological deadspace (VDphys), arterial to end-tidal carbon dioxide partial pressure difference (PaCO2-PE' CO2) and PaCO2. VCO2 increased after insufflation of carbon dioxide with a mean (SD) maximum increase of 32 (28)% co...

The purpose of the study was to investigate the influence of training with reduced breathing frequency (RBF) on tidal volume during incremental exercise where breathing frequency was restricted and on ventilatory response during exercise when breathing a 3% CO2 mixture. Twelve male participants were divided into two groups: experimental (Group E) and control (Group C). Both groups participated ...

UNLABELLED Hyperventilation performed by athletes during preparation for resistance exercise might contribute to reports of postexercise orthostatic instability. PURPOSE To test the hypothesis that post-resistance exercise orthostatic instability is associated with exaggerated reductions of cerebral blood-flow velocity after hyperventilation. METHODS We recorded the ECG, end-tidal CO2, beat...

Appreciating that CO2 modifies the chemical reactivity of nitric oxide (NO)-derived inflammatory oxidants, we investigated whether hypercapnia would modulate pulmonary inflammatory responses. Rabbits (n = 72) were ventilated with approximately 7-ml/kg tidal volume for 6 hours. Animals were randomized to one of the following conditions: eucapnia (Pa(CO2) at approximately 35-40 mm Hg), eucapnia +...

To analyze the mechanism of the cerebral vasodilator effect of ketamine in anesthetized rabbits, we measured the internal carotid blood flow with an electromagnetic flowmeter, the arterial pressure, intracranial pressure, end-tidal CO2, and the electroencephalogram. Ketamine injection (1 mg/kg) induced a significant cerebral vasodilatation that was blocked by scopolamine, a cholinergic antagoni...