Effects of Dexmedetomidine on Respiratory Mechanics and Oxygenation During One Lung Ventilation With Chronic Obstructive Lung Disease

Study Overview
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Brief Summary
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COPD is often associated with the airflow limitation and the pulmonary hyperinflation. During the one-lung ventilation (OLV), COPD patients' physiologic dead space increases and hypercapnia may develop. In addition, an alveolar overdistention by the pulmonary hyperinflation would divert pulmonary blood flow and impair arterial oxygenation. Dexmedetomidine has both vasoconstricting and vasodilatatory effects on a peripheral vasculature and a smooth muscle but its effects on bronchial smooth muscle is unknown. The investigators will evaluate the effects of dexmedetomidine (bolus of 1.0 μg kg-1 over 10 min followed by a continuous infusion at 0.5 μg kg-1 h-1 infusion during one-lung ventilation) as bronchodilator in COPD patients when administered during surgery with the one lung ventilation. If result successfully shows the effect of dexmedetomidine as a predominantly a vasodilator on bronchial tree, the investigators study can support the dexmedetomidine as a vasodilator for pulmonary vessels and bronchial smooth muscle and as an excellent adjunct to anesthetic agents in COPD patients during the OLV.

Conditions
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COPD, One Lung Ventilation

Intervention / Treatment
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* Drug: saline infusion
* Drug: dexmedetomidine infusion


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Above 40 years of age American Society of Anesthesiologists (ASA) Physical Status I, II, III. COPD diagnosed , criteria ( on preop. PFT : FEV1 < 80%, FEV1 / FVC < 70% after bronchodilator) thoracic surgical procedure Exclusion Criteria: severe functional liver or kidney disease diagnosed HF ( NYHA class >3) arrhythmia or received treatment with antiarrythmic drug . exceed BMI > 30 kg/ m2 bradycardia (HR <50 bpm)

Ages Eligible for Study
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Minimum Age: 40 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Placebo Comparator: Control group<br>saline solution | Drug: saline infusion<br>* saline infusion, bolus of 1.0 μg kg-1 over 10 min followed by a continuous infusion at 0.5 μg kg-1 h-1 infusion during one-lung ventilation, intravenous<br>|
| Active Comparator: dexmedetomidine group<br>dexmedetomidine | Drug: dexmedetomidine infusion<br>* dexmedetomidine, bolus of 1.0 μg kg-1 over 10 min followed by a continuous infusion at 0.5 μg kg-1 h-1 infusion during one-lung ventilation, intravenous<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The change of the oxygenation | PaO2/FiO2 ratio | At two-lung ventilation (T1) , 20 min after of one-lung ventilation (T2), 30 mins after Dex or placebo saline infusion (T3), 60 mins after Dex or placebo saline infusion (T4), at the termination of surgery in TLV (T5) |