# Capnographic monitoring using a novel mainstream system during endoscopic ultrasound and endoscopic retrograde cholangiopancreatography: A prospective randomized controlled trial

## TL;DR

A new mainstream capnography system was tested during endoscopic procedures but did not reduce hypoxemia rates.

## Contribution

A novel over-the-biteblock mainstream capnography system was evaluated for feasibility and efficacy in preventing hypoxemia during EUS and ERCP.

## Key findings

- The novel capnography system successfully captured EtCO2 concentrations without hindering procedures.
- There was no significant difference in hypoxemia incidence between the control and capnography groups.
- The system did not prevent hypoxemia in non-obese patients undergoing EUS or ERCP.

## Abstract

Insufficient studies exist on capnography efficacy during endoscopic ultrasound or endoscopic retrograde cholangiopancreatography, and no definitive conclusions have been drawn. To evaluate the feasibility and efficacy of a novel mainstream capnography using an over‐the‐biteblock end‐tidal CO2 (EtCO2) detector in decreasing the risk of hypoxemia during endoscopic ultrasound (EUS) and endoscopic retrograde cholangiopancreatography (ERCP).

Patients undergoing EUS or ERCP with conscious sedation at a single Japanese center were randomized to a control or a novel capnography monitored (intervention) group in a 1:1 ratio. Hypoxemia correction maneuvers were pursued if the oxygen saturation decreased to <92% in the control or intervention group and if a 15‐s suspension of EtCO2 wave occurred in the intervention group. The primary outcome was the incidence of hypoxemic events, defined as oxygen saturation <90%, during the procedures. Secondary outcomes included technical feasibility of EUS and ERCP with the use of this novel over‐the‐biteblock monitor.

In total, 250 patients were enrolled without dropouts or missing data (control group: 125; capnography group: 125). There was no significant difference in the incidence of hypoxemia between the control and capnography groups (29.6% [37/125] vs. 26.4% [33/125]; p = .573). The estimated odds ratio was 0.925 (95% confidence interval: 0.708–1.208). The EtCO2 concentration was successfully captured without impeding endoscopic maneuvers from the beginning to the end of the procedure in all patients.

Although the novel mainstream capnography with an over‐the‐biteblock EtCO2 detector captures the EtCO2 concentration in EUS or ERCP under conscious sedation, it does not lead to the prevention of hypoxemia.

In this randomized controlled trial, Takimoto and colleagues demonstrated that the novel mainstream capnographic bite block detected the end‐tidal CO2 concentration in 250 participants without interfering with EUS and ERCP procedures. In these relatively healthy, non‐obese patients, capnographic monitoring did not reduce the incidence of hypoxemia during EUS and ERCP‐related procedures.