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Ultrasound imaging is a widely used diagnostic technique, whose integration in medical education is constantly growing. The aim of this study was to evaluate chest ultrasound usefulness in teaching respiratory system physiology, students' perception of chest ultrasound integration into a traditional lecture in human physiology, and short-term concept retention. A lecture about respiratory physiology was integrated with ultrasound and delivered to third-year medical students. It included basic concepts of ultrasound imaging and the physiology of four anatomic sectors of the body of a male volunteer, shown with a portable ultrasound device (pleural sliding, diaphragmatic movement, inferior vena cava diameter variations, cardiac movements). Students' perceptions of the integrated lecture were assessed, and attendance recorded. After 4 mo, four multiple-choice questions about respiratory physiology were administered during the normal human physiology examinations, and the results of students who attended the lesson and those of who did not were compared. One hundred thirty-four students attended the lecture. Most of them showed encouragement for the study of the subject and considered the ultrasound integrated lecture more interesting than a traditional one and pertinent to the syllabus. Exposed students achieved a better score at the examination and committed less errors than did nonexposed students. The chest ultrasound integrated lecture was appreciated by students. A possible association between the exposure to the lecture and short-term concept retention is shown by better performances of the exposed cohort at the examination. A systematic introduction of ultrasound into physiology traditional teaching will be promoted by the Ultrasound-Based Medical Education movement.

This article reviews the state of the art about an unclear physiological phenomenon interesting respiratory system tissues, i.e., stress-relaxation. Due to their visco-elastic properties, the tissues do not maintain constant stress under constant deformation. Rather, the stress slowly relaxes and falls to a lower value. The exact molecular basis of this complex visco-elastic behavior is not well defined, but it has been suggested that it may be generated because of the anisotropic mechanical properties of elastin and collagen fibers in the alveolar septa and their interaction phenomena, such as reciprocal sliding, also in relation to interstitial liquid movements. The effects on stress-relaxation of various biochemical and physical factors are reviewed, including the consequences of body temperature variations, respiratory system inflammations and hyperbaric oxygen exposure, endocrinal factors, circulating blood volume variations, changes in inflation volume and/or flow, changes in intra-abdominal pressure because of pneumoperitoneum or Trendelenburg position. The effects of these factors on stress-relaxation have practical consequences because, depending on visco-elastic pressure amount which is requested to inflate the respiratory system in different conditions, respiratory muscles have to produce different values of inspiratory pressure during spontaneous breathing. High inspiratory pressure values might increase the risk of respiratory failure development on mechanical basis., Author(s): Alessandro Rubini[sup.1] , Emanuele Luigi Carniel[sup.2] Author Affiliations: (1) Section Physiology, Department of Biomedical Sciences, University of Padova, Via Marzolo, 3, 35100, Padua, Italy (2) Center of Mechanics of [...]

Background We previously demonstrated that the exposure to hyperbaric hyperoxia increased respiratory system elastance and both the 'ohmic' and viscoelastic components of inspiratory resistances, probably because of increased oxygen tension toxic effects. We presently investigated the possible consequences of a single exposure to 2.5-atmospheres absolute air (hyperbarism) lasting 90 min. Methods We used the end-inflation occlusion method on anesthetized rats after about 15 min from previous exposure to hyperbarism. The method allows the measurements of respiratory system elastance and of the ohmic and viscoelastic components of airway resistance, which respectively depend on the Newtonian pressure dissipation due to the ohmic airway resistance to airflow and on the viscoelastic pressure dissipation caused by respiratory system tissue stress relaxation. The expressions of inducible NO synthase (iNOS) and endothelial NO synthase (eNOS) in the lung's tissues were also investigated, together with the histological characteristics of lung tissue. Data were compared with those obtained in control animals and in previously studied animals exposed to hyperoxic hyperbarism. Results Unlike with hyperoxic hyperbarism, hyperbarism per se did not change significantly the parameters of respiratory mechanics in the control animals (respiratory system elastance and ohmic and viscoelastic resistances were 2.01 ± 0.17 vs. 1.74 ± 0.08 cm H.sub.2O/ml, and 0.13 ± 0.02 vs. 0.13 ± 0.03 and 0.425 ± 0.04 vs. 0.33 ± 0.03 cm H.sub.2O/ml s.sup.-1 in control vs. experimental animals, respectively, none significantly different), nor did it induce evident effects on lung histology. An increment of both iNOS and eNOS expressions was documented instead (0.50 ± 0.05 vs. 0.75 ± 0.07 and 1.04 ± 0.1 and 1.4 ± 0.15, respectively). Conclusion Our results indicate that, at variance with hyperoxic hyperbarism, the acute exposure to only hyperbarism does not affect either the elastic or the resistive respiratory system properties, or lung histology., Author(s): Alessandro Rubini[sup.1] , Andrea Porzionato[sup.2] , Gloria Sarasin[sup.2] , Susi Zara[sup.3] , Veronica Macchi[sup.2] , Enrico Camporesi[sup.4] , Gerardo Bosco[sup.1] [sup.5] Author Affiliations: (1) Department of Biomedical Sciences, Section [...]

Purpose This study was designed to investigate the possible effects of acute hyperbaric hyperoxia on respiratory mechanics of anaesthetised, positive-pressure ventilated rats. Methods We measured respiratory mechanics by the end-inflation occlusion method in nine rats previously acutely exposed to hyperbaric hyperoxia in a standard fashion. The method allows the measurements of respiratory system elastance and of both the 'ohmic' and of the viscoelastic components of airway resistance, which respectively depend on the newtonian pressure dissipation due to the ohmic airway resistance to air flow, and on the viscoelastic pressure dissipation caused by respiratory system tissues stress-relaxation. The activities of inducible and endothelial NO-synthase in the lung's tissues (iNOS and eNOS respectively) also were investigated. Data were compared with those obtained in control animals. Results We found that the exposure to hyperbaric hyperoxia increased respiratory system elastance and both the 'ohmic' and viscoelastic components of inspiratory resistances. These changes were accompanied by increased iNOS but not eNOS activities. Conclusions Hyperbaric hyperoxia was shown to acutely induce detrimental effects on respiratory mechanics. A possible causative role was suggested for increased nitrogen reactive species production because of increased iNOS activity. Keywords End-inflation occlusion method * Hyperbaric hyperoxia * NO-synthase * Rat * Respiratory mechanics, Introduction The exposure to hyperbaric oxygen (HBO) is a widely applied therapeutical approach used for the treatment of diseases, such as ischemia-reperfusion injury, necrotizing vascular diseases, chronic non-healing wounds, gas [...]

Byline: Alessandro. Rubini, Daniele. Monte, Vincenzo. Catena Purpose: To describe the consequences of the cranial displacement of the diaphgram occurring during pneumoperitoneum (Pnp) and/or Trendelenburg (Tnd) position on respiratory mechanics. [...]