Respiratory consequences of red sludge dust inhalation in rats.

The environmental disaster following flooding by red sludge in the Ajka region in Hungary poses a serious public health threat with particular concern regarding the potentially adverse respiratory effects of the inhalation of red sludge dust (RSD). The respiratory consequences of the inhalation of RSD obtained from field samples were investigated in rats. Rats were either exposed to RSD at a high concentration (2 weeks, 8h/day), or kept in room air.

Plethysmographic estimation of thoracic gas volume in apneic mice.

Electrical stimulation of intercostal muscles was employed to measure thoracic gas volume (TGV) during airway occlusion in the absence of respiratory effort at different levels of lung inflation. In 15 tracheostomized and mechanically ventilated CBA/Ca mice, the value of TGV obtained from the spontaneous breathing effort available in the early phase of the experiments (TGVsp) was compared with those resulting from muscle stimulation (TGVst) at transrespiratory pressures of 0, 10, and 20 cmH2O. A very strong correlation (r2= 0.

Acoustic evidence of airway opening during recruitment in excised dog lungs.

The aim of this study was to test the hypothesis that the mechanism of recruitment and the lower knee of the pressure-volume curve in the normal lung are primarily determined by airway reopenings via avalanches rather than simple alveolar recruitments. In isolated dog lung lobes, the pressure-volume loops were measured, and crackle sounds were recorded intrabronchially during both the first inflation from the collapsed state to total lobe capacity and a second inflation without prior degassing. The inflation flow contained transients that were accompanied by a series of crackles.

Changes in respiratory mechanics during cardiac surgery.

Unlabelled: We investigated the role of cardiopulmonary bypass (CPB) in compromised lung function associated with cardiac surgery. Low-frequency respiratory impedance (Zrs) was measured in patients undergoing cardiac surgery with (n = 30; CPB group) or without (n = 29; off-pump coronary artery bypass [OPCAB] group) CPB. Another group of CPB patients received dopamine (DA) (n = 12; CPB-DA group).

Airway and tissue mechanics in anesthetized paralyzed children.

To estimate the mechanical properties of the airways and respiratory tissues, respiratory system impedance (Zrs) was measured with low-frequency forced oscillations in 26 anesthetized, paralyzed children (aged 3 months-10 years) undergoing surgical correction of congenital heart diseases. Zrs was determined from the signals of tracheal flow and pressure between 0.4-12 Hz before surgery at zero mean transrespiratory pressure.

Components of respiratory resistance monitored in mechanically ventilated patients.

The interrupter technique is commonly adopted to monitor respiratory resistance (Rrs,int) during mechanical ventilation; however, Rrs,int is often interpreted as an index of airway resistance (Raw). This study compared the values of Rrs,int provided by a Siemens 940 Lung Mechanics Monitor with total respiratory impedance (Zrs) parameters in 39 patients with normal spirometric parameters, who were undergoing elective coronary bypass surgery. Zrs was determined at the airway opening with pseudorandom oscillations of 0.

Concentration- and time-dependent effect of aminooxyacetic acid on cortical epileptogenicity.

In the present electrophysiological study the effect of aminooxyacetic acid (AOAA) on the cortical epileptogenicity, and on the basic electro-cortical activity was investigated in anesthetized rats. AOAA did not induce spontaneous epileptiform discharges but modified the somato-sensory evoked responses and the cortical epileptogenicity (induced by 4-aminopyridine) in the same manner depending on its concentration. AOAA at low concentrations increased the amplitude of evoked responses and the ipsilateral manifestation of epileptiform activity, however, at high concentrations significantly suppressed both the evoked responses and the induction and expression of seizures discharges.

Scaling behavior in crackle sound during lung inflation.

During slow inflation of lung lobes, we measure a sequence of short explosive transient sound waves called "crackles," each consisting of an initial spike followed by ringing. The crackle time series is irregular and intermittent, with the number of spikes of size s following a power law, n(s) proportional, variants(-alpha), with alpha=2.77+/-0.

Viscosity and density of common anaesthetic gases: implications for flow measurements.

Although viscosity (mu) is a crucial factor in measurements of flow with a pneumotachograph, and density (rho) also plays a role in the presence of turbulent flow, these material constants are not available for the volatile anaesthetic agents commonly administered in clinical practice. Thus, we determined experimentally mu and rho of pure volatile anaesthetic agents. Input impedance of a rigid-wall polyethylene tube (Zt) was measured when the tube was filled with various mixtures of carrier gases (air, 100% oxygen, 50% oxygen+50% nitrogen) to which different concentrations of volatile anaesthetic inhalation agents (halothane, isoflurane, sevoflurane, and desflurane) had been added.

Endothelin-1-induced airway and parenchymal mechanical responses in guinea-pigs: the roles of ETA and ETB receptors.

Endothelin-1 (ET-1) has been shown to have a constrictor effect on the airways and parenchyma; however, the roles of the ETA and ETB receptors in the ET-1-induced changes in the airway and tissue compartments have not been fully explored. Low-frequency pulmonary impedance (ZL) was measured in anaesthetized, paralysed, open-chest guinea-pigs. ZL spectra were fitted by a model to estimate airway resistance (Raw) and inertance (Iaw), and coefficients of tissue damping (G) and elastance (H), and hysteresivity (eta = G/H).

Size distribution of recruited alveolar volumes in airway reopening.

In 11 isolated dog lung lobes, we studied the size distribution of recruited alveolar volumes that become available for gas exchange during inflation from the collapsed state. Three catheters were wedged into 2-mm-diameter airways at total lung capacity. Small-amplitude pseudorandom pressure oscillations between 1 and 47 Hz were led into the catheters, and the input impedances of the regions subtended by the catheters were continuously recorded using a wave tube technique during inflation from -5 cm H(2)O transpulmonary pressure to total lung capacity.

Effects of endothelin-1 on airway and parenchymal mechanics in guinea-pigs.

The contributions of the airways and the parenchyma to the overall lung mechanical response to endothelin-1 (ET-1) have not been systematically studied. In this investigation, the ET-1 induced changes on lung mechanics in guinea-pigs were separated into airway and parenchymal components. Pulmonary impedance (ZL) data were collected between 0.

Mechanical impedance of the lung periphery.

The mechanics of the regional airways and tissues was studied in isolated dog lobes by means of a modified wave-tube technique. Small-amplitude pseudorandom forced oscillations between 0.1 and 48 Hz were applied through catheters wedged in 2-mm-diameter bronchi in three regions of each lobe at translobar pressures (PL) of 10, 7, 5, 3, 2, and 1 cmH2O.

Methacholine-induced bronchoconstriction in rats: effects of intravenous vs. aerosol delivery.

To determine the predominant site of action of methacholine (MCh) on lung mechanics, two groups of open-chest Sprague-Dawley rats were studied. Five rats were measured during intravenous infusion of MCh (i.v.