Volutrauma. What is it, and how do we avoid it?

Lung injury can be initiated at birth with the delivery room resuscitation. Adequate tidal volume must be achieved gradually and adjusted with each subsequent breath to achieve adequate, but not excessive, tidal volume delivery. Time constants vary greatly within the lung because some alveoli are collapsed, and some are inflated

Pulmonary volutrauma — Volutrauma is essentially damage to the lung caused by overdistention by a mechanical ventilator set for an excessively high tidal volume; resulting in a syndrome similar to adult respiratory distress syndrome.[1] Volutrauma is separate from Pulmonary barotrauma because the mechanism of injury is excessive volume (volutrauma), instead of pressure (barotrauma).

A sufi ventilator with multiple modes as CPAP HFO,HFO,CMV SIMV

In the lungs thus greatly reducing volutrauma

AVOIDANCE OF VENTILATOR-INDUCED LUNG INJURY The pressure volume curve of the lung has both upper and lower inflection points. The lower inflection point is the pressure at which lung volume begins to decline sharply with falling airway pressure. This represents the pressure below which atelectasis rapidly accumulates during deflation. The upper inflection point is the pressure at which lung volume ceases to increase sharply with rising airway pressure. This represents the pressure at which the lung begins to stiffen and over distend during inflation. Lung injury might be avoided by ventilating the lung at a PEEP above the lower inflection point, to prevent opening and closure of alveoli, while restricting tidal volume so that end-inspiratory pressure does not exceed the upper inflection point.

Excessive pressure or volume may lead to high stretch injury when already open alveoli are overdistended. Sufficient alveoli must be recruited to establish the optimal functional residual capacity. This establishes an inflation history of the lung that tends to resist alveolar collapse at the end of expiration, provided that adequate mean airway pressure is provided throughout the ventilatory cycle. The best volume of inflation is achieved at the lowest pressure cost.

Maintaining alveolar recruitment with the use of exogenous surfactant and positive end-expiratory pressure avoids alveolar collapse and injury with succeeding distending breaths. Although there have been significant advances in neonatal respiratory care, further improvement in outcomes may be expected by successfully avoiding ventilator-induced lung injury.

as a treatment of infants, children, and adults with acute respiratory failure. In HFOV, high mean airway pressure is maintained by rapid flow of gas across an outlet valve. The air column is oscillated 5 to 15 times per second, generating tidal volumes smaller than the patient’s dead space. This oscillation facilitates movement of CO2 from the patient to the respiratory circuit of the oscillator, from which it is removed by the brisk flow of gas toward the outlet valve. This technique provides excellent lung expansion. Its high mean airway pressure minimizes the opening and closure of alveoli. The small oscillations in alveolar pressure avoid peak pressures above the upper inflection point, as well as expiratory pressures below the lower inflection point. HFOV has been shown to reduce direct oxidative injury to the lung in a surfactant washout model of respiratory distress[11].

Inhaled nitric oxide Nitric Oxide (NO) is a gaseous

pulmonary vasodilator that may be delivered by inhalation. By that route, it dilates distal vessels of alveoli, if and only if they are ventilated. This facilitates matching of ventilation to perfusion in the lung. It has been argued that inhaled NO may reduce the airway pressure needed to ventilate the lung and adequately oxygenate the patient. Documentation that NO

improves outcome in patients with respiratory failure is lacking, though it is of clear benefit in the treatment of

pulmonary hypertension[12].

Extracorporeal membrane oxygenation Extracorporeal membrane oxygenation (ECMO) is partial cardiopulmonary bypass. It entails removal of venous blood from the right atrium and re-infusion of oxygenated blood into a vein, the right atrium or the aorta. ECMO is not, of itself, therapeutic. It does, however, clearly reduce the need for injurious ventilatory strategies. The goal of mechanical ventilation during ECMO can focus on maintaining the lung in an open position. Like HFOV, ECMO eliminates the need to apply airway pressures beyond the upper and lower inflection points. ECMO has been shown to improve outcome in the neonate with persistent pulmonary

hypertension of the newborn, presumably by reducing the tendency to injure the lung in the course of supporting the patient’s gas exchange[13]. Liquid ventilation Partial liquid

Liquid ventilation Partial liquid ventilation (PLV) and total or tidal liquid ventilation (TLV) are experimental techniques in which the lungs are filled to some volume with a perfluorochemical liquid having high solubilities for oxygen and carbon dioxide and low surfacetension. The lungs are then

ventilated with gas (PLV)[14] or oxygenated perfluorocarbon (TLV)[15]. These techniques take advantage of the low surface tension of the perfluorocarbon to reduce the airway pressures required to ventilate the surfactant deficient lung. They maintain alveolar expansion in expiration by maintaining an alveolar volume of perfluorocarbon. They further take advantage of anti-inflammatory properties of the perfluorocarbon to reduce lung inflammation[16] and oxidative injury[17,18]. Other means of delivering perfluorochemicals, such as nebulization and vaporization, have also been used to apply the beneficial properties of these liquids to the lungs. Though laboratory studies demonstrate lung protection by PLV, neither technique has

Abdul fattah abro R.N

Karachi sindh Pakistan