Purpose of review
Describe the importance of monitoring dead space
during thoracic surgery, specifically during one-lung ventilation
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 CO2
during thoracic surgery sufficiently high.
Monitoring dead space
helps anesthesiologists monitor the status of the lung and find appropriate ventilatory settings during thoracic surgeries.