no patient enrolled.

Studies have shown that intravenous infusion and nebulized dexmedetomidine can improve lung function in mechanically ventilated patients, including those with preoperative COPD, exerting lung protection. However, these studies are based on mechanical ventilation patients under general anesthesia, and more intuitive research is needed on whether dexmedetomidine can also exercise pulmonary precaution in awake patients. Pulmonary function monitoring is the most direct way to evaluate changes in lung function in awake patients. Portable pulmonary function machines can assess lung function in a variety of settings. In addition, compared with intravenous administration, nebulized inhalation administration directly acts on the mucosa of the respiratory tract, does not involve invasive operations, and has higher safety and comfort. Therefore, this study intends to use portable pulmonary function instruments and non-invasive ambulatory respiratory monitors to evaluate the effect of nebulized dexmedetomidine on lung function in COPD patients to guide the perioperative management of COPD patients.

Chronic obstructive pulmonary disease (COPD) is a common respiratory disease that seriously endangers the physical and mental health of patients. Surgical patients with COPD will increase the risk of postoperative pulmonary complications and the risk of complications of extrapulmonary organs such as heart and kidney, and lead to prolonged hospital stay, increased medical costs, and increased perioperative mortality. Therefore, it is necessary to explore drugs with lung protection effects to improve the perioperative safety of COPD patients.

Dexmedetomidine (Dex) is a new type of highly selective α2-adrenergic receptor agonist, which has the effects of sedative-hypnotic, anti-inflammatory, stress reduction, hemodynamic stabilization, analgesia, and organ protection, and has little inhibitory effect on respiratory function. In recent years, studies have found that dexmedetomidine may have the effect of improving lung function. In addition, human studies have found that intravenous infusion of dexmedetomidine (loading dose 0.5 to 1 μg/kg or 0.5 to 0.7 μg/kg/hour) can reduce inflammation levels, improve oxidative stress, reduce plateau pressure, peak airway pressure, airway resistance, and improve lung compliance, thereby improving oxygenation and postoperative pulmonary complications, and promoting patient recovery. In obese patients undergoing laparoscopic gastric reduction, intraoperative intravenous dexmedetomidine infusion (loading dose of 1 μg/kg, followed by 1 μg/kg/hour) improves lung compliance and oxygenation. One study found that intraoperative intravenous infusion of dexmedetomidine (loading dose of 1 μg/kg, followed by 0.5 μg/kg/hour) increased forced expiratory volume in one second and improved postoperative oxygenation on days 1 and 2 after one-lung ventilation. Another study found that nebulized inhalation of 0.5 μg/kg, 1 μg/kg, and 2 μg/kg dexmedetomidine in one-lung ventilation for thoracic surgery improved lung compliance and oxygenation.

These studies have shown that intravenous infusion and nebulized dexmedetomidine can improve lung function in mechanically ventilated patients, including those with preoperative COPD, exerting lung protection. However, these studies are based on mechanical ventilation patients under general anesthesia, and more intuitive research is needed on whether dexmedetomidine can also exercise pulmonary precaution in awake patients. Pulmonary function monitoring is the most direct way to evaluate changes in lung function in awake patients. Portable pulmonary function machines can assess lung function in a variety of settings. In addition, compared with intravenous administration, nebulized inhalation administration directly acts on the mucosa of the respiratory tract, does not involve invasive operations, has limited effect, high safety, fewer side effects, and higher comfort. Therefore, this study intends to use portable pulmonary function instruments and non-invasive ambulatory respiratory monitors to evaluate the effect of nebulized dexmedetomidine on lung function in COPD patients to guide the perioperative management of COPD patients.

Inclusion Criteria:

1. Patients with diagnosed COPD who are scheduled to undergo elective surgery (FEV1/FVC ratio< 0.70)
2. Patients with mild, moderate, and severe COPD (FEV1≥30% predicted)
3. Age ≥ 40 years old, ≤ 80 years old
4. American Society of Anesthesiologists (ASA) Physical Situation Grading I-III
5. Able to cooperate with the experiment, voluntarily participate and be able to understand and sign the informed consent form

Exclusion Criteria:

1. Obese patients (BMI>28 kg/m2)
2. Patients with grade 3 hypertension (systolic blood pressure ≥180 mmHg and/or diastolic blood pressure ≥110 mmHg)
3. Patients with myocardial infarction and shock in the past 3 months
4. Patients with unstable angina pectoris with NYHA heart function grade III or IV in the last 4 weeks
5. Tachycardia (heart rate >120 beats/min), bradycardia (heart rate <45 beats/min), and degree II or III atrioventricular block
6. Patients with severe or uncontrolled bronchial asthma, pulmonary infection, bronchiectasis, thoracic malformation, pneumothorax, hemothorax, giant pulmonary bulla, and massive hemoptysis in the last 4 weeks
7. Pulmonary artery pressure ≥60 mmHg
8. Patients with Child B or C liver function
9. Patients with stage 4 or 5 chronic kidney disease
10. Patients with hyperthyroidism and pheochromocytoma
11. Patients with seizures requiring medication
12. Pregnant women
13. Patients with tympanic membrane perforation
14. Patients allergic to dexmedetomidine;
15. For any reason, it is not possible to cooperate with the study or the researcher considers it inappropriate to be included in this experiment

Individual participant data (IPD) will be available with the corresponding author when required.

The data will be available when we publish and keep it for five years.

Researchers who provide a methodologically sound proposal.