Transnasal Microstream EtCO2 Reduces Hypoxemia During Emergence in Aged Post-Abdomen Surgery

June 16, 2026 updated by: Jianbo Wu

Effect of Transnasal Microstream Capnography on Incidence of Hypoxemia During Emergence From General Anesthesia in Elderly Patients After Abdominal Surgery: A Prospective Randomised Controlled Trial

This prospective, randomized controlled study aims to investigate whether transnasal microstream end-tidal carbon dioxide (EtCO₂) monitoring in the post-anesthesia care unit (PACU) reduces the incidence of postoperative hypoxemia in elderly patients (65-80 years, ASA I-III, BMI 18-30 kg/m²) undergoing elective laparoscopic surgery under general anesthesia with endotracheal intubation. A total of 324 patients will be randomized 1:1 to either the control group (standard SpO₂ monitoring and clinical observation with oxygen delivery at 2 L/min via sampling line) or the experimental group (same oxygen delivery plus continuous real-time transnasal microstream EtCO₂ monitoring). The primary outcome is the incidence of hypoxemia (SpO₂ < 90% for >15 seconds) after extubation in the PACU. Secondary outcomes include severe hypoxemia (SpO₂ < 85%), lowest SpO₂ during PACU stay, vital signs at specified time points, PACU length of stay, and other adverse events. Statistical analysis will use chi-square or Fisher's exact test for the primary outcome, with a sample size calculated to detect a reduction in hypoxemia from 33% (control) to 18% (experimental group) (α=0.05, power=80%, plus 20% dropout).

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Study Title:

Effect of Transnasal Microstream End-Tidal Carbon Dioxide Monitoring on the Incidence of Postoperative Hypoxemia in Elderly Patients Undergoing Laparoscopic Surgery under General Anesthesia with Endotracheal Intubation: A Prospective, Randomized Controlled Study

Principal Investigator: Wu Jianbo Department: Anesthesiology and Perioperative Medicine

Background & Objective:

Postoperative hypoxemia is a common respiratory complication in the post-anesthesia care unit (PACU). Conventional pulse oximetry (SpO₂) has a delayed response to hypoventilation, especially during supplemental oxygen therapy. This study aims to investigate whether adding transnasal microstream end-tidal carbon dioxide (EtCO₂) monitoring in the PACU reduces the incidence of hypoxemia in elderly patients after laparoscopic surgery under general anesthesia.

Study Design:

Prospective, randomized, controlled, interventional study.

Participants:

324 elderly patients (age 65-80 years, ASA I-III, BMI 18-30 kg/m²) scheduled for elective laparoscopic surgery under general anesthesia with endotracheal intubation.

Interventions:

Control group (n=162): Routine monitoring with SpO₂ and clinical observation; oxygen delivery at 2 L/min via sampling line without EtCO₂ monitoring.

Experimental group (n=162): Same oxygen delivery plus continuous real-time transnasal microstream EtCO₂ monitoring.

Primary Outcome:

Incidence of postoperative hypoxemia (SpO₂ < 90% for >15 seconds) after extubation in the PACU.

Secondary Outcomes:

Incidence of severe hypoxemia (SpO₂ < 85% for >15 seconds) Lowest SpO₂ during PACU stay Vital signs at predefined time points

PACU length of stay (Steward Recovery Score ≥ 4)

Other adverse events (e.g., nausea, vomiting, agitation, shivering)

Safety Monitoring:

Device-related adverse events (nasal irritation, bleeding), respiratory events (bradypnea, apnea, airway obstruction), and serious adverse events (e.g., need for advanced airway, cardiovascular events) will be recorded and managed according to a stepwise intervention protocol.

Randomization and Blinding:

1:1 randomization using block randomization (SAS 9.4) with allocation concealment (sealed, opaque envelopes). Partial blinding: participants, outcome assessors, and statisticians blinded; anesthesiologists/operators unblinded.

Sample Size Calculation:

Based on pilot data (expected hypoxemia rate: 33% in control vs. 18% in experimental group), α=0.05, power=80%, plus 20% dropout → 162 patients per group (total N=324).

Statistical Analysis:

SPSS 22.0 will be used. Continuous variables (normal distribution) will be compared using t-test; non-normally distributed variables using Mann-Whitney U test. Categorical variables (e.g., hypoxemia incidence) will be compared using chi-square or Fisher's exact test.

Expected Significance:

This study will provide high-level evidence on whether transnasal microstream EtCO₂ monitoring in the PACU can enhance respiratory safety in elderly patients recovering from laparoscopic surgery, potentially reducing hypoxemia and related complications.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
324

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Older Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Age 65-80 years;
  • ASA physical status I-III;
  • BMI 18-30 kg/m²;
  • Participants scheduled for elective laparoscopic surgery under general anesthesia with endotracheal intubation;
  • Willing to participate in the study and provide written informed consent

Exclusion Criteria:

  • Patients with nasal bleeding, nasal mucosal injury, nasal cavity occupancy, or other conditions that preclude transnasal carbon dioxide monitoring;
  • Patients undergoing emergency surgery;
  • Participants requiring postoperative assisted ventilation via endotracheal intubation or tracheostomy;
  • Presence of any disease or condition that may cause abnormal end-tidal carbon dioxide waveforms or abnormal baseline pulse oximetry (e.g., congenital heart disease or chronic lung disease);
  • Severe cardiac insufficiency (≤4 Metabolic Equivalents [MetS]);
  • Severe renal insufficiency (acute kidney injury [AKI] or chronic kidney disease [CKD] stage 4 or higher);
  • Severe hepatic insufficiency (Child-Pugh class C or worse);
  • Allergy to study medications;
  • Daily alcohol intake ≥60 grams;
  • History of psychiatric disorders such as depression, severe central nervous system depression, Parkinson's disease, basal ganglion lesions, schizophrenia, epilepsy, Alzheimer's disease;
  • Participation in another related clinical study within the past 3 months.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Prevention
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Triple

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Active Comparator: Control Group (Routine Monitoring Group)
After endotracheal extubation, the sampling end of the sampling line is placed between the patient's mouth and nose, and oxygen is delivered at 2 L/min via the sampling line. The patient receives only routine monitoring (including continuous pulse oximetry and clinical observation) and is not connected to the end-tidal carbon dioxide (EtCO₂) monitoring device.
Other: Routine Monitoring
After extubation, the sampling line is placed between the patient's mouth and nose to deliver oxygen at 2 L/min. The patient receives routine monitoring including continuous pulse oximetry (SpO₂) and clinical observation, but is not connected to the EtCO₂ monitoring device.
Experimental: Experimental Group (EtCO₂ Monitoring Group)
After endotracheal extubation, the sampling end of the sampling line is placed between the patient's mouth and nose, and oxygen is delivered at 2 L/min via the sampling line. At the same time, the sampling line is connected to the monitor to initiate continuous real-time transnasal microstream end-tidal carbon dioxide monitoring.
Device: EtCO₂ Monitoring
After extubation, the sampling line is placed between the patient's mouth and nose to deliver oxygen at 2 L/min. The sampling line is connected to a patient monitor (RespArrayTM) to initiate continuous real-time transnasal microstream end-tidal carbon dioxide (EtCO₂) monitoring throughout the post-anesthesia care unit (PACU) stay.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Incidence of post-extubation hypoxemia (SpO₂ < 90% for >15 seconds)
Time Frame: During the period in the post-anesthesia care unit (PACU) (up to 1 days)
Closely monitor vital signs, and record the number of episodes of hypoxemia (defined as SpO₂ < 90% lasting for >15 seconds) following tracheal extubation after the patient is transferred from the operating room to the PACU.more than 15 seconds
During the period in the post-anesthesia care unit (PACU) (up to 1 days)

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Incidence of severe hypoxemia: proportion of patients with SpO₂ < 85% lasting > 15 seconds
Time Frame: During the period in the post-anesthesia care unit (PACU) (up to 1 days)
Closely monitor the patient's vital signs, and record the proportion of patients with severe hypoxemia (SpO₂ < 85% lasting >15 seconds) following tracheal extubation after transfer from the operating room to the PACU
During the period in the post-anesthesia care unit (PACU) (up to 1 days)
Lowest SpO₂ value during PACU stay Lowest SpO₂ value during PACU stay Lowest SpO₂ value during PACU stay
Time Frame: During the period in the post-anesthesia care unit (PACU) (up to 1 days)
Observe and record the lowest SpO₂ value during the patient's stay in the PACU
During the period in the post-anesthesia care unit (PACU) (up to 1 days)
PACU length of stay
Time Frame: During the period in the post-anesthesia care unit (PACU) (up to 1 days)
time from entering the PACU until achieving a Steward recovery score >4, meeting the criteria for discharge
During the period in the post-anesthesia care unit (PACU) (up to 1 days)
Other adverse events
Time Frame: During the period in the post-anesthesia care unit (PACU) (up to 1 days)
Record adverse events occurring during the entire PACU stay
During the period in the post-anesthesia care unit (PACU) (up to 1 days)
Record the changes in heart rate following the patient's admission to the PACU
Time Frame: During the period in the post-anesthesia care unit (PACU) (up to 1 days)
Record the patient's heart rate at T0 (on PACU admission), T1 (1 min post-extubation), T2 (5 min post-extubation), T3 (10 min post-extubation), T4 (15 min post-extubation), T5 (20 min post-extubation), and T6 (on PACU discharge)
During the period in the post-anesthesia care unit (PACU) (up to 1 days)
Record the patient's blood pressure after admission to the PACU
Time Frame: During the period in the post-anesthesia care unit (PACU) (up to 1 days)
Record the patient's blood pressure values at T0 (on PACU admission), T1 (1 min post-extubation), T2 (5 min post-extubation), T3 (10 min post-extubation), T4 (15 min post-extubation), T5 (20 min post-extubation), and T6 (on PACU discharge)
During the period in the post-anesthesia care unit (PACU) (up to 1 days)
Record the changes in the patient's SpO₂ values after admission to the PACU
Time Frame: During the period in the post-anesthesia care unit (PACU) (up to 1 days)
Record the patient's SpO₂ values at T0 (on PACU admission), T1 (1 min post-extubation), T2 (5 min post-extubation), T3 (10 min post-extubation), T4 (15 min post-extubation), T5 (20 min post-extubation), and T6 (on PACU discharge)
During the period in the post-anesthesia care unit (PACU) (up to 1 days)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Jianbo Wu

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Jianbo WU, Doctoral, Shandong First Medical University

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
July 1, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
July 1, 2028

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
October 1, 2028

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
June 5, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
June 16, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
June 17, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
June 17, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
June 16, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
June 1, 2026

More Information

Terms related to this study

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • YXLL-KY-2026(147)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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