This may produce high Ppl, which might overdistend vulnerable lung regions. In respiratory failure, when PEEP is set, the tidal volume (when using pressure controlled ventilation) or the airway pressure above PEEP (when using volume controlled ventilation) are not adjusted. A patient with very low compliance (e.g., ARDS) would be expected to have a lower alveolar volume at the same Ppl level (35 cmH 2O) and hence to be at lower risk of barotrauma. A patient with emphysema (high lung compliance) and elevated Ppl (35 cmH 2O) would be expected to have a large end-expiratory alveolar volume and thus be at risk of barotrauma. Certainly, the volume is related to the pressure by the compliance characteristics of the lung and chest wall. The Ppl and more correctly the transpulmonary pressure (Ppl-Ppleural) reflect the compliance of the respiratory system, given the initial PEEP level and the delivered tidal volume and gauge the maximum alveolar pressure and hence maximal alveolar volume. This Ppl is the pressure applied to the small airways and alveoli. In volume control modes of ventilation, when the Ppk reaches its maximum value, there is a rapid drop of the pressure until a plateau is reached (plateau pressure-Ppl). It increases with hyperinflation, but it has no pathological value in the clinical setting, since it arises from the increased airway resistance and the high inspiratory flow rate and is mainly dissipated in the airways and thus does not reach the alveoli. The peak airway pressure (Ppk) is the pressure measured by the ventilator in the major airways and it strongly reflects airway resistance. In each case hyperinflation occurs when the inspired air cannot be totally expired (dynamic hyperinflation) ( 20- 29).Īll forms of pressure are not equal as barotrauma aetiologic factors. This suggests that risk factors predisposing to barotrauma are a severe underlying lung disease, which seriously affects alveoli and all factors predisposing to hyperinflation: high transpulmonary pressure (airway pressure minus the pleural pressure), high tidal volumes, high intrinsic PEEP. In case of mediastinal parietal rupture pneumothorax is appeared.Īll barotrauma forms come from rupture of a hyperinflated alveolus and air leak into the surrounding tissues and spaces. The air can be decompressed both retroperitoneally and intraperitoneally (pneumoperitoneum). When adequate air is accumulated in mediastinum, it is decompressed along cervical fascial planes into the subcutaneous tissues and subcutaneous emphysema is formed. Air can be introduced along the perivascular sheaths into the mediastinum and pneumomediastinum or pneumopericardium are present. When an overdistended alveolus ruptures, air is diffused into the perivascular adventitia, resulting in PIE. The two terms-barotrauma and volutrauma-reflect the two sides of the same phenomenon: the lung injury due to a large distending volume and/or to a high airway pressure ( 10- 19).Ĭlinical manifestations of barotrauma include pneumothorax, pulmonary interstitial emphysema (PIE), subcutaneous emphysema, pneumoperitoneum, pneumomediastinum or pneumopericardium, air embolisation, tension lung cysts, and hyperinflated left lower lobe. Volutrauma is the term that describes ultrastructural lung injury due to overdistention occurring during mechanical ventilation. Nevertheless, it seems that not only pressure, but high lung volume and lung hyperinflation as well, play a major role in barotrauma aetiology. According to the etymology, barotrauma refers only to high pressures. VALI and VILI can be divided into macrobarotrauma (the form of radiologically detected barotrauma) and microbarotrauma, with diffuse lung injury and possible injury of other organs due to release of inflammatory mediators-biotrauma. ![]() This is described as ventilator associated lung injury (VALI) or ventilator induced lung injury (VILI). The implementation of positive pressure ventilation predisposes an already affected lung-when certain limits are overcome-to injury. It is defined as the presence of extraalveolar air in locations, where it is not normally found in patients receiving mechanical ventilation ( 1- 9). Barotrauma must be considered as complication of the use of positive pressures in a tissue, where normal air movement is mainly passive. While human being is created, as other creatures, to breathe with a mechanism based on negative pressures, the patient on mechanical ventilation is ventilated with positive pressures, which is not physiological. ![]() Intubation and mechanical ventilation are common but aggressive therapeutic manoeuvres in anesthesia or in ICU setting. Keywords: Barotrauma pneumothorax ICU ventilation
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