The document discusses various strategies to avoid ventilator-induced lung injury in infants, children, and adults with acute respiratory failure. It describes how using excessive pressure or tidal volume can overdistend and damage already open alveoli. Maintaining adequate PEEP and restricting tidal volume to below the upper inflection point on the pressure-volume curve can prevent injury. Techniques like high-frequency oscillatory ventilation, inhaled nitric oxide, extracorporeal membrane oxygenation, and partial/total liquid ventilation aim to minimize alveolar opening and closing while avoiding excessive pressures and volumes. Though experimental, these advanced strategies may help further improve outcomes by preventing ventilator-induced lung injury.

1.  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

2.  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).

6.  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.

7.  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.

8.  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.

9.  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].

10.  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].

11.  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

12.  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

13.  Abdul fattah abro R.N
 Karachi sindh Pakistan