Minerva anestesiologica
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The pressure-volume curve of the respiratory system is a physiological method used for diagnotic purposes to describe the static mechanical properties of the respiratory system. A renewal of interest in the pressure-volume curve has recently appeared because of experimental evidence regarding the information conveyed by the curve, a better understanding of the pathophysiologic factors influencing its interpretation and the beneficial results of clinical trials based on the use of the pressure-volume curve for ventilatory management of acute respiratory distress syndrome. Thus, adapting ventilatory settings to individual characteristics of the patients in terms of respiratory mechanics may be an extremely important aspect for a better management of the most difficult to ventilate patients with acute lung injury. ⋯ The low-flow technique using ventilator technology has several potential advantages. It is hopeful to think that in the future the measurement of the P-V curve and the quantification of alveolar recruitment may be easily provided at the bedside and may help for the titration of the ventilatory settings in clinical practice. This review will focus briefly on the physiologic background, technique description, and recent advances concerning the interpretation of the P-V curve in the critically ill patients.
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Minerva anestesiologica · Apr 2001
Review[Physiopathology of acute respiratory failure in COPD and asthma].
Asthma and chronic obstructive pulmonary diseases (COPD) lead to functional obstruction of airways, identified by increased inspiratory and expiratory resistances. Increased expiratory resistances cause, in turn, a reduction in expiratory flow. The analysis of flow-volume loops shows that, as the disease progresses, the flow generated during expiration of a tidal volume becomes very close to the flow generated during forced maximal expiration. ⋯ Ventilatory support of COPD patients should decrease work of breathing and improve gas exchange without increasing hyperinflation. This target can be achieved during assisted ventilation by applying a positive pressure both during inspiration and expiration; the level of PEEP should equal PEEPi. During mechanical ventilation in sedated paralyzed patients hyperinflation should be limited by decreasing minute volume and by increasing expiratory time, eventually choosing controlled hypercapnia.
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Minerva anestesiologica · Apr 2001
ReviewPathophysiology and treatment of airway mucociliary clearance. A moving tale.
Airway hygiene depends largely on mucociliary clearance (MCC) which in turn depends upon the movement of viscoelastic mucus along the airway by the beating of the ciliary appendages of airway epithelial cells. Failure to keep the airways sterile by MCC results in a host inflammatory response to the persistent microorganisms which, if it becomes chronic, causes damage to the airway wall and upregulation of mucus production manifest clinically as bronchiectasis, sinusitis and otitis. There are three principal disorders of MCC. ⋯ Secondly, secondary ciliary dyskinesia due principally to microbial toxin-induced dysfunction of the energy pathways required for ciliary beating. Thirdly, abnormalities in the physicochemical properties of mucus, including reduced salt content/osmolality which results in it being unsuitable in quality for cilia to move it. Methods of rectifying this defect promise to restore MCC to normal and interfere in the vicious circle of inflammatory lung damage.
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Minerva anestesiologica · Apr 2001
Case ReportsExperiences with continuous intra-arterial blood gas monitoring.
Management of critically ill patients requires frequent arterial blood gas analyses for assessing the pulmonary situation and adjusting ventilator settings and circulatory therapeutic measures. Continuous arterial blood gas analysis is a real-time monitoring tool, which reliably detects the onset of adverse pulmonary effects. It gives rapid confirmation of ventilator setting changes and resuscitation and helps to ensure precise adjustment of therapy. ⋯ The Paratrend 7+ sensor proved to be clinical feasible and showed an improved precision in terms of clinical situations with an arterial pO2 smaller than 50 kPa. However, the results are not much different regarding the findings with older systems consisting of hybrid technology combining optodes and electrochemical oxygen measurement. The advantages might be seen if the sensor is used for a period over several days in patients on ICU as demonstrated by the two case reports.