What are the pulmonary adverse effects of mechanical ventilation?

Updated: Apr 07, 2020
  • Author: Allon Amitai, MD; Chief Editor: Zab Mosenifar, MD, FACP, FCCP  more...
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Answer

Answer

Barotrauma may result in pulmonary interstitial emphysema, pneumomediastinum, pneumoperitoneum, pneumothorax, and/or tension pneumothorax. High peak inflation pressures (>40 cm water) are associated with an increased incidence of barotrauma. However, note that separating barotrauma from volutrauma is difficult, since increasing barometric pressure is usually accompanied by increasing alveolar volume.

Experimental models of high peak inflation pressures in animals with high extrathoracic pressures have not demonstrated direct alveolar damage from increased pressure without increased volume as well. Thus, the statement that high airway pressures result in alveolar overdistention (volutrauma) and accompanying increased microvascular permeability and parenchymal injury may be more accurate. Alveolar cellular dysfunction occurs with high airway pressures. The resultant surfactant depletion leads to atelectasis, which requires further increases in airway pressure to maintain lung volumes.

High-inspired concentrations of oxygen (fraction of inspired oxygen [FiO2] >0.5) result in free-radical formation and secondary cellular damage. These same high concentrations of oxygen can lead to alveolar nitrogen washout and secondary absorption atelectasis.

It has been theorized that pulmonary biophysical and biomechanical injury in the presence of bacterial lung infections contributes to bacterial translocation and bacteremia.


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