1,345 research outputs found
Principles and practice of mechanical ventilation
No full textClinical evidence highlights the importance of limiting airway pressure during mechanical ventilation. In addition, experimental results suggest the importance of avoiding lung overdistension and cyclic end–expiratory airspace collapse and reexpansion, indicating that both phenomena promote mechanical damage an release of inflammatory mediator. In this context, transtracheal oxygen therapy and tracheal gas insufflation could have a role as adjuncts to mechanical ventilation
Closing, opening and reopening: the difficult coexistence
No full textVolume-controlled ventilation (VCV) has always been considered as protective ventilation, in particular during spontaneous breathing, being able to avoid the administration of injurious tidal volumes (Vt) to the patient. In fact, spontaneous efforts increase transpulmonary pressure (Pl) only during pressure-regulated ventilations (1). Despite this difference in terms of Pl, the conditions of lung parenchyma determine the damage to the lung tissue and
the onset of ventilator induced lung injury (VILI). In normal lung the pressures applied to a local region of the pleura are homogeneous and distributed over the whole lung (fluid-like behavior), whereas negative pleural pressures (Ppl) generated by diaphragmatic contraction are rather concentrated in dorsal parts (solid-like), once lung has been injured (2). Furthermore, when Pl is applied to the lung, a counterforce of equal intensity is developed (lung
stress), whereas the associated lung deformation is called strain. These two forces are directly correlated by the specific elastance (Elsp), which reflects the intrinsic mechanical characteristics of the lung parenchyma (3). This concept is a recent introduction, but it has an important clinical relevance right away; in fact, Elsp is peculiar in each species: in pigs is about half that in human and consequently a plateau pressure (Pplat) of 30 cmH2O in pigs would approximately correspond to 60 cmH2O in humans
Dead space
No full textDead space is that part of the tidal volume that does not
participate in gas exchange. Although the concept of
pulmonary dead space was introduced more than a
hundred years ago, current knowledge and technical
advances have only recently lead to the adoption of dead
space measurement as a potentially useful bedside clinical
too
High-frequency ventilation is/is not the optimal physiological approach to ventilate ARDS patients
No full textOmeostasi termica perioperatoria
No full textIl parametro fondamentale nella fisiologia della termoregolazione dell'animale è la temperatura corporea. Essa governa i mecanismi omeostatici che consentono un equilibrio tra produzione e dispersione del calore. Il corpo produce calore attraverso il metabolismo basale e l'esercizio fisico, ossia un lavoro, e lo scambio termico con l'ambiente avviene per convenzione, irraggiamento, conduzione ed evaporazione
Dead space in acute respiratory distress syndrome: More than a feeling!
No full textWhy clinicians are slow to implement advances in diagnosis and treatment from well-designed clinical trials is a continuously debated question in critical care. For instance, prone positioning significantly improves mortality in patients with severe acute respiratory distress syndrome (ARDS), but the usefulness of recruitment measures in this population is still under debate. Nevertheless, a recent observational study in intensive care units in 50 countries found that prone positioning was used in only 16.3 % of patients with severe ARDS, whereas recruitment maneuvers were used in 32.7 % [1].
Similarly, despite the established usefulness of measuring physiologic variables such as dead space in mechanically ventilated ARDS patients, this practice is not widely employed
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