S
Safe apnoea time: the duration for which the blood oxygen saturation can be maintained at a safe level in the face of an interruption to alveolar ventilation.
Sustained exhaled carbon dioxide: exhaled carbon dioxide detection sufficient to satisfy the criteria for excluding oesophageal intubation. These criteria are:
Amplitude rises during exhalation & falls during inspiration
Consistent or increasing amplitude over at least 7 breaths
Peak amplitude more than 1 kPa (7.5mmHg, 0.1%) above baseline
Reading is clinically appropriate
All four criteria must be satisfied in order to declare that ‘sustained exhaled carbon dioxide’ is present.
Previously the only term in use to address this concept was ‘adequate’ carbon dioxide. The term sustained exhaled carbon dioxide was developed to precisely define what is meant by ‘adequate’ thereby providing a clear trigger below which airway practitioners are obligated to actively exclude oesophageal intubation.
Note that this term only applies when an airway is being established via tracheal intubation. It has no relevance to determining the adequacy of exhaled carbon dioxide when ventilation is being attempted with a facemask, supraglottic airway or during monitoring of CO2 via an open system in a sedated patient.
