The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
Tsuyoshi Shimizu - One of the best experts on this subject based on the ideXlab platform.
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effects of isoprenaline on the responses of slowly adapting pulmonary stretch receptors to reduced Lung Compliance and to administered histamine
Neuroscience Letters, 1994Co-Authors: Shigeji Matsumoto, Tsuyoshi ShimizuAbstract:Abstract To define the difference between the reponses of slowly adapting pulmonary stretch receptors (SARs) to reduced dynamic Lung Compliance (Cdyn) and to administered histamine, experiments were performed in open-chest, artificially ventilated, bilaterally vagotomized rabbits with positive end-expiratory pressure (PEEP). Both stimuli caused an increase in tracheal pressure and produced augmentation of SAR activities during inflation and deflation. Isoprenaline treatment that blocked the responses of SARs and P T to histamine had no effect on those to reduced Cdyn. The results suggest that the response characteristics of SARs provoked by histamine administration do not involve the contribution of decreased Cdyn.
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effects of atropine on the responses of rapidly adapting pulmonary stretch receptors and dynamic Lung Compliance to sodium cyanide induced hyperpnea
Journal of The Autonomic Nervous System, 1993Co-Authors: Shigeji Matsumoto, Tadanori Nagayama, Masao Yamasaki, Takahiro Kanno, Tsuyoshi ShimizuAbstract:Abstract The responses of tracheal pressure (P T ) and heart rate (HR) to electrical stimulation of the peripheral cut-ends of the vagus nerves (10–15 V, 10 Hz, 1 ms) to activate both myelinated and non-myelinated fibers were examined before and after administration of atropine (1 mg/kg) in artificially ventilated, bilaterally vagotomized rabbits. Vagal stimulation caused an increase in P T and a decrease in HR. The P T response to vagal stimulation was completely blocked by atropine which significantly reduced the bradycardia evoked by the stimulation. In other series of experiments, we also examined the responses of rapidly adapting pulmonary stretch receptors (RARs) and dynamic Lung Compliance (Cdyn) to intravenous injections of sodium cyanide (NaCN, 20 and 30 μg/kg) before and after administration of atropine (1 mg/kg) in spontaneously breathing rabbits with vagal efferent activities. Administration of NaCN led to an increase in RAR activity associated with a decrease in Cdyn, and these two effects became more prominent by increasing the dose of NaCN. Atropine treatment did not significantly alter the responses of RARs and Cdyn to the injections of NaCN with different doses. These results suggest that the changes of RAR activity and Cdyn produced by hyperpnea due to NaCN administration are not influenced by the vagally mediated bronchoconstriction.
H M Coleridge - One of the best experts on this subject based on the ideXlab platform.
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response of slowly adapting pulmonary stretch receptors to reduced Lung Compliance
Journal of Applied Physiology, 1991Co-Authors: J Yu, T E Pisarri, J C G Coleridge, H M ColeridgeAbstract:We examined the steady-state response of slowly adapting pulmonary stretch receptors (SAPSRs) to reduced Lung Compliance in open-chest cats with Lungs ventilated at eupneic rate and tidal volume (VT) and with a positive end-expiratory pressure (PEEP) of 3–4 cmH2O. Transient removal of PEEP decreased Compliance by approximately 30% and increased transpulmonary pressure (Ptp) by 1–2.5 cmH2O. Reduction of Compliance significantly decreased SAPSR discharge in deflation and caused a small increase in discharge at the peak of inflation; it had little effect on discharge averaged over the ventilatory cycle. Increasing VT to produce a comparable increase in Ptp significantly increased peak discharge. Thus unlike rapidly adapting receptors, whose discharge is increased more effectively by reduced Compliance than by increased VT, SAPSRs are stimulated by increased VT but not by reduced Compliance. We speculate that the most consistent effect of reduced Compliance on SAPSRs (the decrease in deflation discharge) was due to the decreased time constant for deflation in the stiffer Lung. This alteration in firing may contribute to the tachypnea evoked as the Lungs become stiffer.
Eduardo Bancalari - One of the best experts on this subject based on the ideXlab platform.
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a new method to analyze Lung Compliance when pressure volume relationship is nonlinear
American Journal of Respiratory and Critical Care Medicine, 1998Co-Authors: Werner Nikischin, Tilo Gerhardt, Ruth Everett, Eduardo BancalariAbstract:Changes in dynamic Lung Compliance during inspiration and expiration cannot be modeled accurately with conventional algorithms. We developed a simple method to analyze pressure-volume (P/V) relationships under condition of nonlinearity (APVNL) and tested it in a Lung model with known resistance and nonlinear P/V relationship. In addition, pulmonary mechanics in 22 infants, 11 of them with nonlinear P/V relationships, were analyzed with the new method. The findings were compared with those obtained by a recently introduced algorithm, multiple linear regression analysis (MLR) of the equation of motion. The APVNL method described the changing Compliance (C) of the Lung model accurately, whereas the MLR method underestimated C especially in the first half of the breath. In infants the MLR method gave highly variable, often nonphysiological C values in the beginning of a breath. In contrast, the coefficient of variability of measurements obtained by the APVNL method was significantly smaller (p < 0.02), and the indices of model-fit showed better agreement between calculated and observed pressure than for the MLR method (p < 0.02). We conclude that the APVNL method accurately describes nonlinear P/V relationships present during spontaneous breathing or mechanical ventilation. The method may be helpful in identifying and preventing pulmonary overdistention.
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increased incidence of sighs augmented inspiratory efforts during synchronized intermittent mandatory ventilation simv in preterm neonates
Pediatric Pulmonology, 1997Co-Authors: Helmut Hummler, Tilo Gerhardt, Ruth Everett, Alvaro Gonzalez, Nelson Claure, Eduardo BancalariAbstract:A reflex resulting in a deep, sigh-like inspiratory effort (augmented breath) is frequently triggered during synchronized mechanical ventilation in preterm infants. We studied the incidence of augmented inspiratory efforts and their effect on ventilation and Lung Compliance during conventional IMV and synchronized IMV (SIMV) in 15 preterm neonates (GA 26.7 +/- 1.5 wks (mean +/- SD), BW 925 +/- 222 g, age 1-8 days). Augmentation of spontaneous inspiratory effort was defined as an esophageal pressure deflection occurring coincident with a synchronized mechanical breath and exceeding the previous unassisted spontaneous effort by more than 50%. The incidence of augmented breaths was higher during SIMV (11.1 +/- 7.7%; P < 0.01) than during conventional IMV (5.1 +/- 6.1%). However, when the synchronized breaths were triggered late (200-300 msec) after the onset of inspiration, augmented breaths occurred no more frequently than during conventional IMV (6.0 +/- 4.7%). The incidence of augmented breaths correlated inversely with dynamic Lung Compliance (P = 0.014), but was not significantly influenced by a change in PEEP. Although inspiratory effort increased nearly three times during the augmented breaths, tidal volume increased only 12%. The change in tidal volume was limited because the augmented effort reached its maximal negativity only approximately 500 ms after the beginning of the synchronized, mechanical breath and at a time when the mechanical breath had already ended. For this reason the augmented effort did not contribute significantly to minute ventilation, but only prolonged inspiration. Dynamic Lung Compliance did not change significantly after an augmented breath. The results indicate that augmented inspiratory efforts are more common in preterm neonates ventilated with SIMV than with conventional IMV, but do not contribute significantly to ventilation.
Shigeji Matsumoto - One of the best experts on this subject based on the ideXlab platform.
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effects of isoprenaline on the responses of slowly adapting pulmonary stretch receptors to reduced Lung Compliance and to administered histamine
Neuroscience Letters, 1994Co-Authors: Shigeji Matsumoto, Tsuyoshi ShimizuAbstract:Abstract To define the difference between the reponses of slowly adapting pulmonary stretch receptors (SARs) to reduced dynamic Lung Compliance (Cdyn) and to administered histamine, experiments were performed in open-chest, artificially ventilated, bilaterally vagotomized rabbits with positive end-expiratory pressure (PEEP). Both stimuli caused an increase in tracheal pressure and produced augmentation of SAR activities during inflation and deflation. Isoprenaline treatment that blocked the responses of SARs and P T to histamine had no effect on those to reduced Cdyn. The results suggest that the response characteristics of SARs provoked by histamine administration do not involve the contribution of decreased Cdyn.
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effects of atropine on the responses of rapidly adapting pulmonary stretch receptors and dynamic Lung Compliance to sodium cyanide induced hyperpnea
Journal of The Autonomic Nervous System, 1993Co-Authors: Shigeji Matsumoto, Tadanori Nagayama, Masao Yamasaki, Takahiro Kanno, Tsuyoshi ShimizuAbstract:Abstract The responses of tracheal pressure (P T ) and heart rate (HR) to electrical stimulation of the peripheral cut-ends of the vagus nerves (10–15 V, 10 Hz, 1 ms) to activate both myelinated and non-myelinated fibers were examined before and after administration of atropine (1 mg/kg) in artificially ventilated, bilaterally vagotomized rabbits. Vagal stimulation caused an increase in P T and a decrease in HR. The P T response to vagal stimulation was completely blocked by atropine which significantly reduced the bradycardia evoked by the stimulation. In other series of experiments, we also examined the responses of rapidly adapting pulmonary stretch receptors (RARs) and dynamic Lung Compliance (Cdyn) to intravenous injections of sodium cyanide (NaCN, 20 and 30 μg/kg) before and after administration of atropine (1 mg/kg) in spontaneously breathing rabbits with vagal efferent activities. Administration of NaCN led to an increase in RAR activity associated with a decrease in Cdyn, and these two effects became more prominent by increasing the dose of NaCN. Atropine treatment did not significantly alter the responses of RARs and Cdyn to the injections of NaCN with different doses. These results suggest that the changes of RAR activity and Cdyn produced by hyperpnea due to NaCN administration are not influenced by the vagally mediated bronchoconstriction.
J Yu - One of the best experts on this subject based on the ideXlab platform.
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response of slowly adapting pulmonary stretch receptors to reduced Lung Compliance
Journal of Applied Physiology, 1991Co-Authors: J Yu, T E Pisarri, J C G Coleridge, H M ColeridgeAbstract:We examined the steady-state response of slowly adapting pulmonary stretch receptors (SAPSRs) to reduced Lung Compliance in open-chest cats with Lungs ventilated at eupneic rate and tidal volume (VT) and with a positive end-expiratory pressure (PEEP) of 3–4 cmH2O. Transient removal of PEEP decreased Compliance by approximately 30% and increased transpulmonary pressure (Ptp) by 1–2.5 cmH2O. Reduction of Compliance significantly decreased SAPSR discharge in deflation and caused a small increase in discharge at the peak of inflation; it had little effect on discharge averaged over the ventilatory cycle. Increasing VT to produce a comparable increase in Ptp significantly increased peak discharge. Thus unlike rapidly adapting receptors, whose discharge is increased more effectively by reduced Compliance than by increased VT, SAPSRs are stimulated by increased VT but not by reduced Compliance. We speculate that the most consistent effect of reduced Compliance on SAPSRs (the decrease in deflation discharge) was due to the decreased time constant for deflation in the stiffer Lung. This alteration in firing may contribute to the tachypnea evoked as the Lungs become stiffer.
