The range of measurements for the CO2 fraction (FCO2) or the corresponding partial pressure (PCO2) in the breathing gas is identical in neonates and adults. The much lower amount of exhaled CO2 makes capnography in neonates more difficult, because there are objective limits for the size of the analyzer chamber or the magnitude of suction flow used with sidestream devices. For intraoperative monitoring, time-based capnography is commonly used, and the shape of the capnogram provides robust qualitative data and the PETCO2. In emergency medicine, critically ill infants often require tracheal intubation before transportation to the hospital. Capnography is a simple, non-invasive technique used to obtain information on alveolar ventilation and the deadspaces of the respiratory system. Compared with the more simple, time-based capnography, volumetric capnography measurements have a much higher informative potential, and enable the calculation of the different airway deadspaces.

Since gas exchange is a primordial function of the lungs and the conductive airways, respiratory assessment is of paramount importance. Capnography has been utilized in surgical patients for over three decades to confirm tracheal intubation and assess ventilation. Nitrogen washout provides an estimate of functional residual capacity, total lung volume, deadspace volume, and alveolar volume. Clinicians typically utilize exhaled CO2 concentration against time during a respiratory cycle. A number of applications are available in and out of the operating room. Capnography can be used as a continuous monitor of alveolar ventilation in patients with lung disease or hemodynamic instability. Mainstream capnometry appears to provide more accurate PETCO2 than conventional sidestream capnometry during spontaneous breathing in non-intubated patients. In the opinion of some investigators, the technology should be employed in all cases requiring sedation in or out of the operating room.