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R L Santos

Publications and source records attributed to R L Santos.

23 records · Page 2Linked to original sources
PubMed1992

Alveolar pressure measurement in open-chest rats.

In open-chest rats, alveolar pressure was measured with alveolar capsules connected via pliable tubing to inductive pressure transducers. By means of the interrupter technique during constant-flow inflation, it was possible to determine pulmonary static elastance (Est,L) and tissue and airway resistances (Rdiff,L and Rinit,L, respectively). In eight anesthetized paralyzed mechanically ventilated rats, 118 measurements of Rdiff,L and Est,L were performed over a wide range of flows and tidal volumes. There was excellent agreement between the data calculated using transpulmonary pressures and those computed using capsule pressures, the latter being measured at different points of the lung. In another group of rats studied under the same experimental conditions, two capsules were simultaneously placed on different pulmonary lobes. No regional differences in pulmonary mechanics could be detected in either experiment. In addition, alveolar pressure could also be measured accurately by a catheter inserted into lung parenchyma.

Animals↗
PubMed1992

Effects of longitudinal laparotomy on respiratory system, lung, and chest wall mechanics.

In six sedated, anesthetized, paralyzed, and mechanically ventilated guinea pigs, total respiratory system (RT,rs), lung, and chest wall resistances and respiratory system (Est,rs), lung, and chest wall (Est,w) elastances were determined before and after longitudinal laparotomy. Furthermore the resistances were also split into their initial and difference components, with the former reflecting the Newtonian resistances and the latter representing the viscoelastic/inhomogeneous pressure dissipations in the system. For such purpose the end-inflation occlusion during constant inspiratory flow method was used. During laparotomy, a statistically significant increase in respiratory system difference resistance (from 0.086 to 0.101 cmH2O.ml-1.s) significantly augmented RT,rs (from 0.157 to 0.167 cmH2O.ml-1.s). The former was entirely secondary to a significant increase in chest wall difference resistance (0.019 to 0.034 cmH2O.ml-1.s), which naturally raised chest wall total resistance (from 0.030 to 0.047 cmH2O.ml-1.s). Est,rs and Est,w also increased (14.7 and 13.1%, respectively) after abdominal incision. It can be concluded that the midline xiphipubic laparotomy accompanied by the bilateral ventrodorsal infracostal incision increases RT,rs as a consequence of augmented chest wall difference resistance and Est,rs as a result of higher Est,w.

Airway Resistance↗
PubMed1992

Respiratory system mechanics in patients treated with isotonic or hypertonic NaCl solutions.

Twenty-one patients who underwent elective surgery for coronary artery bypass were studied right after chest wall closure. They were anesthetized, paralyzed, and artificially ventilated with a constant-flow ventilator. Airflow, changes in lung volume, and tracheal pressure were measured. Respiratory system resistance (Rrs,max) was partitioned into its homogeneous (Rrs,min) and uneven (Rrs,u) components. Respiratory system elastance (Ers) was also measured. The subjects were randomly divided into two groups injected with test solutions just after chest wall closure: eleven patients received isotonic saline (0.9% NaCl solution), whereas the remaining ten were injected with hypertonic saline (7.5% NaCl solution). In all patients, mechanical parameters were measured at six different times: just before infusion, at 5 and 10 min (end of infusion); and at 15, 20, and 25 min after beginning of injection. No statistically significant differences were observed in respiratory system mechanical parameters between groups or between different times within each group. Our data suggest that hypertonic saline infusion does not result in significant changes in respiratory system mechanics in patients submitted to coronary artery bypass.

Adult↗
PubMedDate not supplied

Animal models of Salmonella infections: enteritis versus typhoid fever.

The most common disease syndromes caused by Salmonella serotypes in humans, typhoid fever and enteritis, can be modeled using Salmonella enterica serotype Typhimurium infections in mice and calves, respectively. This article reviews murine typhoid and bovine enteritis and discusses strengths, limitations and distinctive features of these animal models.

Animals↗