Endotracheal Tube Intolerance and Respiratory Airflow Perception

August 11, 2026 updated by: Yi Feng, MD, Peking University People's Hospital

Association Between Preoperative Oronasal Breathing Patterns and Endotracheal Tube Intolerance During Emergence From General Anesthesia: A Prospective Nested Case-Control Study

This is a case-control study designed to enroll 224 patients who will undergo tracheal intubation for general anesthesia in the operating rooms of Peking University People's Hospital between July 20, 2026, and October 31, 2026. The case group will consist of patients who develop coughing before extubation (N=112), while the control group will comprise those without coughing before extubation (N=112).

Data to be collected include general demographic characteristics, smoking and smoking cessation history, comorbid conditions (with particular attention to snoring during sleep and sleep apnea-hypopnea syndrome [SAHS]), history of pulmonary diseases, mode of spontaneous breathing, surgical and anesthetic data, as well as blood pressure and heart rate before, during, and after extubation, pain scores, and sedation levels.

Continuous variables will be presented as mean ± standard deviation (for normally distributed data) or median with interquartile range (IQR) (for non-normally distributed data). Categorical variables will be described using frequencies and percentages (e.g., sex, smoking history). Baseline differences between the case and control groups will be compared using the chi-square test (for categorical variables), Student's t-test (for normally distributed continuous variables), or the Mann-Whitney U test (for non-normally distributed continuous variables). Multivariable logistic regression analysis will be employed to evaluate the independent association between the mode of spontaneous breathing and coughing before extubation, with adjustment for potential confounding factors, and odds ratios (ORs) with their 95% confidence intervals (95%CI) will be calculated. All statistical analyses will be performed using SPSS or R software.

Study Overview

Status

Not yet recruiting

Conditions

Detailed Description

Eligible patients will be enrolled for observation. Based on whether coughing occurs before extubation after emergence from anesthesia, patients will be divided into a case group (those who develop coughing) and a control group (those who do not).

Non-invasive cuff blood pressure readings will be recorded before, during, and after extubation. Post-extubation pain scores and sedation levels (assessed using the Ramsay Sedation Scale) will also be documented.

General demographic characteristics, smoking and smoking cessation history, presence of snoring during sleep, comorbid conditions (with particular emphasis on sleep apnea-hypopnea syndrome), history of pulmonary diseases, mode of spontaneous breathing, and surgical and anesthetic data will be collected.

Primary outcome: occurrence of coughing before extubation after emergence from anesthesia.

Definition of coughing: Coughing is defined as the occurrence of cough in a patient who has emerged from anesthesia after administration of reversal agents at the end of surgery, while the tracheal tube is still in place and connected to the ventilator in manual ventilation mode (with the adjustable pressure limiting [APL] valve set at 0 cmH₂O), and when extubation criteria have been met but the tube has not yet been removed.

Severity of coughing is graded as follows:

0 = no cough;

= single cough;
= more than one non-sustained cough;
= sustained and repetitive cough with head lifting.

Data collection methods: General demographic and surgical/anesthetic data will be retrieved retrospectively from the patients' medical and anesthesia records. Other relevant data, including the occurrence and severity of coughing, pain scores, sedation levels, and mode of spontaneous breathing, will be recorded directly by the investigators in the case report forms (CRFs).

Investigators: research staff who have undergone standardized training.

This is an exploratory, unmatched case-control study designed to investigate the association between coughing during emergence from general anesthesia and the mode of spontaneous breathing (nasal vs. oral) in patients. In the pilot study, the proportion of nasal breathing in the case group (cough) was 65%, while that in the control group (no cough) was 35%. With a two-sided significance level (α = 0.05) and a statistical power of 90%, the required sample size per group was calculated using the Schlesselman formula to be 89 patients. Accounting for a 20% dropout rate, a total of 224 patients (112 per group) are planned for final enrollment. If the observed difference in exposure proportions is smaller than anticipated, the recruitment period will be extended or the analytical strategy will be adjusted accordingly.

Study Type

Observational

Enrollment (Estimated)

224

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

Name: Xiaoyan Li
Phone Number: 010-88325581
Email: lixiaoyan_j@163.com

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

Ages Eligible for Study

Child
Adult
Older Adult

Accepts Healthy Volunteers

Yes

Sampling Method

Probability Sample

Study Population

A total of 224 patients undergoing general anesthesia with endotracheal intubation in the operating rooms of Peking University People's Hospital will be recruited between July 20, 2026, and October 31, 2026.

Description

Inclusion Criteria:

Patients undergoing general anesthesia with endotracheal intubation;
Written informed consent obtained.

Exclusion Criteria:

Patients with severe psychiatric disorders;
Deaf or mute patients who are unable to answer questions;
Patients who develop postoperative cognitive dysfunction and are consequently unable to answer questions;
Patients who withdraw from the study prematurely;
Patients who are extubated after being transferred to the recovery room or intensive care unit (i.e., extubation not performed in the operating room).

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

Number of groups / cohorts

Cohorts and Interventions

Group / Cohort
Mouth Breathing The patients' breathing pattern is predominantly oral.
Nasal Breathing The patients' breathing pattern is predominantly nasal.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Endotracheal Tube Intolerance Time Frame: Pre-extubation period	Definition of Bucking / Emergence Coughing: Bucking is defined as a reflexive cough occurring during the emergence phase following the administration of reversal agents at the conclusion of surgery. It manifests while the patient is mechanically ventilated in the manual ventilation mode via the endotracheal tube (with the adjustable pressure-limiting [APL] valve set at 0 cmH₂O), after extubation criteria have been met but prior to the actual removal of the tracheal tube. Severity Grading of Bucking (Clinical Scale): Grade 0: No bucking. Grade 1: Isolated, single cough. Grade 2: Intermittent coughing (more than one episode, non-sustained). Grade 3: Sustained, repetitive coughing accompanied by head lifting (indicating severe emergence agitation/reflex).	Pre-extubation period

Collaborators and Investigators

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

Sponsor

Peking University People's Hospital

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

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)

September 1, 2026

Primary Completion (Estimated)

October 31, 2026

Study Completion (Estimated)

October 31, 2026

Study Registration Dates

First Submitted

July 22, 2026

First Submitted That Met QC Criteria

August 11, 2026

First Posted (Actual)

August 12, 2026

Study Record Updates

Last Update Posted (Actual)