Mainstream capnography

An airway adapter adapted to be disposed below nostrils of a human subject and comprising:

• a gas case comprising multiple gas outlets arranged to be positioned in vicinity of the nostrils of the human subject when the airway adapter is attached on a face of the human subject;
• a gas delivery tube in fluid communication with the gas case;
• a prong case comprising at least one nasal prong arranged to collect nasally exhaled breath from the human subject;
• and
• an airway case defining an airway passage in fluid communication with the prong case, wherein the airway case comprises:
• a first light window into the airway passage;
• and
• a second light window into the airway passage, wherein the airway adapter is connectable to a mainstream capnography sensor comprising at least one light source and at least one light detector to position the mainstream capnography sensor onto the airway adapter to align the at last one light source with the first light window and align the at least one light detector with the second light window.

A portable monitor for monitoring a spontaneously breathing human subject, wherein the portable monitor comprises:

• a sensor port connectable to a sensor cable of a mainstream capnography sensor;
• an adapter receptacle connectable to a flow measurement adapter;
• a first pressure port configured to be in fluid communication with a gas flow through the flow measurement adapter upstream of a flow restriction;
• a second pressure port configured to be in fluid communication with the gas flow through the flow measurement adapter downstream of the flow restriction;
• a differential pressure sensor in fluid communication with the first pressure port and the second pressure port and configured to measure a pressure difference between the first pressure port and the second pressure port and generate an output signal representative of the pressure difference;
• a processor communicatively connected to the sensor port and the differential pressure sensor;
• and
• a memory coupled to the processor and comprising instructions executable by the processor to cause the processor to:
• process an output signal received at the sensor port and generated by the mainstream capnography sensor to generate a CO2 parameter value representative of partial pressure of CO2 in the exhaled air from the human subject;
• and
• process the output signal from the differential pressure sensor to generate a flow rate value representative of a flow rate of the gas flow.