Mohammad Goudarzi-Rad, RN, PhD Candidate: No financial relationships to disclose
Overview/Abstract:
Background: Opioid analgesics are routinely used for postoperative pain management but are associated with adverse effects such as unexpected sedation and respiratory depression (RD). Post-anesthesia care unit (PACU) nurses use physiological monitoring devices to detect and respond to RD, which may manifest as bradypnea, apnea, and hypoxemia. Capnography monitoring offers real-time observation of apnea, reduced respiratory rate, and hypoventilation. Early recognition of RD is only beneficial if followed by timely intervention, including verbal or tactile stimulation to arouse the patient from narcosis and restore ventilation.
Rationale: An alternative to clinician monitoring and intervention is a device that can both promptly detect and treat signs of RD and swiftly initiate an intervention aimed at restoring ventilation. Mild transcutaneous electrical stimulation (TES) can effectively stimulate breathing and restore normal ventilation. We developed a system to use Transcutaneous Electrical Stimulation for apnea detected by Capnography (TESCapno) to be used in clinical trials.
Methods: This prospective, pilot randomized controlled trial is being conducted on 60 postoperative patients. Adults at Toronto General Hospital, Canada, undergoing elective surgery and receiving general anesthesia are eligible to participate. Participants are randomly assigned to either the intervention or control group. All patients are continuously monitored by capnography (attached to the TES device) for up to one hour in the PACU. Patients in the intervention group receive TES on their arm to arouse them from narcosis in response to apnea lasting at least 10 seconds. Patients in the control group are monitored by capnography connected to the TES device, but the TES electrode does not deliver stimulation. Patients, PACU nurses, and other healthcare providers (anesthesiologists and surgeons) are blinded to group allocation.
Preliminary
Results: Following Ethics approval, data collection is underway. Sixteen patients have been enrolled, and twelve have completed the study protocol. Recruitment is progressing steadily at a rate of two to three participants per week.
Impact: TESCapno represents a promising, automated, and non-invasive strategy for the early detection and management of RD in PACU.
Description of Current State: Postoperative RD has received increasing attention as potentially preventable cause of death and brain damage as most adverse events related to opioids can be prevented by assessing high-risk patients, implementing better monitoring, and intervening early. Mild transcutaneous electrical stimulation (TES) can effectively stimulate breathing and restore normal ventilation during periods of apnea. The Mayo Clinic developed an Oxistimulator system to provide TES and to help patients resume breathing in response to decreased oxygen saturation levels (SpO2 < 93%,). In a randomized controlled trial of 106 postoperative patients in PACU, peripheral TES applied during RD decreased the duration and magnitude of hypoxemia. However, the majority of postoperative patients in the PACU receive supplemental oxygen, and monitoring with only pulse oximetry delays detection of RD. By contrast, capnography can continuously track end-tidal carbon dioxide (EtCO2) levels and enable detection of irregular breathing patterns (e.g. apnea) before any impact on oxygen saturation can be observed. Since capnography is superior to continuous pulse oximetry for detecting respiratory depression in patients who receive supplemental oxygen, it is possible that Transcutaneous Electrical Stimulation for apnea detected by Capnography (TESCapno) will be more effective than Oxistimulator to identify the point at which stimulation should be applied.
