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The 'CO2-Go' system demonstrated successful fulfilment of all initial design requirements shown in Table 1 below. The waveform is clean enough to provide an easy reading to an anesthesiologists and the capability to detect pathology from the waveform visually. This satisfies the initial requirement for detecting pathology in the waveform. The casing was also tested in a one meter drop test successfully, however the electronics were not implemented in the casing during the test to reduce potential loss of expensive components. The device successfully passes all design criteria and was determined a success by the project sponsors during OR testing and final review.
Design Solution
A compact device with an attached monitor screen that allows care transporters to simultaneously monitor the patients’ EtCO2 levels while transporting them on the gurney.
The system altogether fit within a 7”x7” footprint and is able to easily clamp onto an IV pole. All electronics, sensors, and pneumatics are contained within the 3D printed casing and all connections use universal luer connectors to integrate with existing medical systems. Everything runs on an internal battery contained within the casing. The display is centered on the front of the casing.
The system has a simple workflow detailed in the usage flow chart in Fig 1. The system connects easily with existing medical solutions for capnographic monitoring, using the same mask and sampling tube. It all powers on and off quickly with one switch.
Fig. 1 - Design solution and usage flow chart.
Performance Results
Table 1 - Final design results evaluation.
Table 2 - Operating room gold standard evaluation results.
Fig. 2 - Gold standard evaulation against GE Carescape Module.
A gold standard evaluation test was completed alongside the project sponsor and anesthesiologist Dr. Jeffrey Chapman. The system was used in the operating room in parallel with the GE Carescape module, the standard for current EtCO2 monitoring. The system was attached to a mask through a sampling tube on the left and the GE Carescape module was attached to the mask through a sampling tube on the right. As the subjects breathed, both systems would sample the air simultaneously. This ensures that they are measuring the same air composition from each breath and eliminates the confounding variable of varying breath CO2 output.
The system was tested in this manner without oxygen flowing into the mask with four participants, all four members of the project team, Matthew Kim, Miheer Potdar, Nolan Sim, and Owen Crocker. Each participant would record the EtCO2 value for ten different breaths. Afterwards, the test was repeated with oxygen flowing into the mask to mimic actual use with a patient.
Furthermore, the system was tested for the rise time from the patient exhaling to the system displaying their breath EtCO2 value. The time taken for an alarm to go off when detecting apnea was also tested by having the participant continuously breath and then take the mask off after exhalation. All results were compared against the GE Carescape module which was used as the ground truth value. The results of the test are summarized in Table 2.
Fig. 3 - Electronics and pneumatic system inside CO2-Go casing (left) and charging port, clamp and mask mounted to the back of the casing (right)
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