Transcutaneous Electrical Stimulation for Apnea Detected by Capnography

Summary

After surgery, patients often recover in a special area called the Post Anesthesia Care Unit (PACU). Patients may receive pain medications either during the surgery or afterward in the PACU. While these medications are important for controlling pain, some of them can slow down breathing.

To ensure patients' breathing remains safe, the nurses in the PACU monitor respiratory rate (how many breaths a patient takes per minute) and oxygen levels using standard monitoring equipment. This is the usual way they check for breathing concerns. If these monitors show that a patient's breathing has slowed down too much, nurses may wake the patient up or stimulate them using their voice or gentle physical touch to encourage deeper breaths.

What is this study about? This research is testing a new approach that uses an additional monitor called capnography. Capnography helps detect slowing or stopping of breathing by measuring the carbon dioxide (CO2) exhaled by patients. If the monitor shows slowed or stopped breathing (called apnea, lasting at least 10 seconds), this study will test using a technology called transcutaneous electrical stimulation (TES) to encourage normal breathing.

How does TES work? TES provides a slight, annoying sensation on the patient's skin-enough to wake them up without causing pain. This has been used in other studies to safely restore breathing after surgery. In this study, the researchers are testing whether a new automated device can deliver TES when the capnography monitor detects breathing issues. The goal is to test the feasibility (can this system work in the PACU?) and acceptability (how do patients feel about this approach?) of this technology.

Who can join this study? Adults aged 18 or older who received general anesthesia and medications (opioids) for pain control during or after surgery are eligible. Patients recovering from surgery in the PACU at Toronto General Hospital may be invited to participate.

Why is this study important? The study aims to reduce the risk of opioid-related breathing problems after surgery, making recovery safer and more comfortable for patients.

Conditions

• Respiratory Depression
• Opioids

Interventions

DEVICE

transcutaneous electrical nerve stimulation (TENS)

A TENS 3000-unit, which is FDA and health Canada approved (Licence No.: 95655) and operated by a small 9V block battery will be used. Potential participants will receive a detailed written explanation of the TES protocol and a brief demonstration of how it works, including the feeling produced by the skin stimulator. Patient-specific TES thresholds will be determined after informed written consent for study participation is obtained. Surface electrode pads will be placed on the ventral surface of the forearm, and 1-Hz pulses will be gradually administered with an increase in current. Patients will be asked to report when they first feel the stimulation and when it becomes annoying. The milliamp current associated with these two levels of stimulation will be recorded on the participant's baseline data collection form. The "annoying" thresholds for all study participants will be used to deliver stimuli in response to respiratory depression in the PACU.

Sponsors & Collaborators

• University Health Network, Toronto

  collaborator OTHER

• University of Toronto

  lead OTHER

Study Design

Allocation

RANDOMIZED

Purpose

OTHER

Masking

DOUBLE

Model

PARALLEL

Eligibility

Min Age

18 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2025-04-10

Primary Completion

2026-03-01

Completion

2026-12-30

Countries

• Canada

Study Locations