Main stream capnographs VS Side stream capnographs

Types of Capnographs
Main-stream capnographs Side-stream capnographs
Side-stream CO2
CO2 sensor located between endotracheal tube and breathing circuit Sensor is located in the main unit and CO2 is aspirated via a sampling tube connected to a T-piece adapter located between endotracheal tube and breathing circuit.
Side-stream Capnographs
Advantages Disadvantages
Easy to connect
No problems with sterilization
Can be used in awake patients
Easy to use when patient is in unusual positions such as in prone position
Can be used in collaboration with simultaneous oxygen administration via a nasal prong
Delay in recording due to movement of gases from the ET to the unit
Sampling tube obstruction
Water vapor pressure changes affect CO2 concentrations
Pressure drop along the sampling tube affects CO2 measurements
Deformity of capnograms in children due to dispersion of gases in sampling tubes
Main-stream Capnographs
Advantages Disadvantages
No sampling tube
No obstruction
No affect due to pressure drop
No affect due to changes in water vapor pressure
No pollution
No deformity of capnograms due to non dispersion of gases
No delay in recording
Suitable for neonates and children
Contrary to the earlier versions, the newer sensors are light weight minimizing traction on the endotracheal tube. (see below)
Long electrical cord, but it is lightweight.
Facial burns have been reported with earlier versions. This has been eliminated with newer sensors (see below)
Sensor windows may clog with secretions. However, they can be replaced easily as they are disposable.
Difficult to use in unusual patient positioning such as in prone positions.
The newer versions use disposable sensor windows thereby eliminating sterilization problem (see below)