Which diagnoses should be considered and excluded in patients undergoing mechanical ventilation?

Updated: Apr 07, 2020
  • Author: Allon Amitai, MD; Chief Editor: Zab Mosenifar, MD, FACP, FCCP  more...
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One of the first diagnoses that should be considered in any hemodynamically unstable patient undergoing positive-pressure ventilation is tension pneumothorax. This is a clinical diagnosis and should be detected and treated with needle decompression prior to obtaining a chest radiograph.

A second diagnosis to exclude, particularly in patients with asthma or COPD, is intrinsic PEEP. As discussed, intrinsic PEEP occurs as a result of incomplete exhalation, which subsequently leads to hyperinflation, increased intrathoracic pressure, decreased venous return, and decreased preload. The diagnosis of intrinsic PEEP may be made by performing an end-expiratory hold or by detecting a non-zero end-expiratory flow on the ventilator. The treatment for intrinsic PEEP is to allow for lung deflation, then to alter mechanical ventilation settings to allow for longer expiratory times by decreasing the respiratory rate, decreasing the tidal volume, or changing the inspiratory-to-expiratory ratio.

Other diagnoses to consider are an obstructed endotracheal tube and an endotracheal tube cuff leak. In the case of endotracheal tube obstruction, attempts to manually ventilate the patient are met with a significant amount of resistance and high-pressure alarms may sound. Endotracheal tube obstruction may be caused by extrinsic compression; tube plugs with mucus, blood, or foreign bodies; tube kinks; or tube biting. Tube suctioning and adequate patient sedation are recommended after other causes of obstruction are ruled out.

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