Purpose of review
Describe the importance of monitoring
dead space during thoracic surgery, specifically during
one-lung ventilation.
Recent findings
The concept of
dead space has gained renewed interest among anesthesiologists ever since breath-by-breath measurement by volumetric capnography became available. Monitoring
dead space during thoracic surgery assesses the ventilatory deficiencies related to increases in instrumental, airway and/or alveolar
dead space, when ventilating patients with positive pressure and double-lumen tubes. Another interesting use of such monitoring is to detect ventilator-induced
lung injury due to tidal overdistension. This type of injury threatens the fragile lungs especially during
one-lung ventilation and can clinically be recognized as an increase in airway and alveolar
dead space above normal values. To date, lung protective ventilation is based on the use of low tidal volumes and airway pressures to decrease overdistension. It has been shown to reduce the incidence of postoperative pulmonary complications after thoracic surgeries. However, such a ventilatory strategy impairs ventilation and induces hypercapnia due to increases in
dead space. Therefore, continuous assessment of
dead space is helpful in guiding ventilation and avoiding overdistension while maintaining the elimination of CO
2 during thoracic surgery sufficiently high.
Summary
Monitoring
dead space helps anesthesiologists monitor the status of the lung and find appropriate ventilatory settings during thoracic surgeries.
