Effects of Iloprost on Pulmonary Oxygenation in Obese Patients During One-lung Ventilation

Study Overview
=================
Brief Summary
-----------------
One lung ventilation (OLV) is essential during thoracic surgery. During OLV, intrapulmonary shunt can be increased resulting hypoxemia. Although OLV technique had been advanced so far, hypoxemia during OLV reaches about 10% in spite of inspired oxygen fraction 100%. Iloprost is a prostaglandin analogue used for pulmonary hypertension, which can decrease pulmonary artery resistance by selectively dilating pulmonary artery. In this prospective, randomized, double blind study, the investigator is planning to investigate the effects of iloprost on respiratory physiology (intrapulmonary shunt, deadspace, oxygenation, etc) in obese patients.

Official Title
-----------------
Effects of Iloprost on Pulmonary Oxygenation in Obese Patients During One-lung Ventilation

Conditions
-----------------
Lung Cancer (Including Metastatic Cancer), Pulmonary Infection

Intervention / Treatment
-----------------
* Drug: normal saline inhalation
* Drug: iloprost inhalation


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: scheduled for VATS lobectomy 40 < age < 80 American Society of Anaesthesiologists(ASA) physical status classification I III BMI > 30 kg /m2 Exclusion Criteria: American Society of Anaesthesiologists(ASA) physical status classification IV or more NYHA class III IV Severe obstructive lung disease and/or restrictive lung disease patients patients with end-organ diseases (i.e. heart failure, respiratory failure, hepatic failure, renal failure) arrhythmia pregnant women pulmonary edema or pulmonary arterial hypertension cerebrovascular disease unstable angina or myocardial infarction within 6 months patients with allergic reaction at iloprost

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

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Placebo Comparator: placebo<br>normal saline inhalation group | Drug: normal saline inhalation<br>* When anesthesia induction finishes, change patients' position from supine to lateral position and measure ABGA, VBGA while two lung is ventilated (T0). After 20 minutes of applying one-lung ventilation, measure ABGA and VBGA (T1). Apply normal saline inhalation for control group and measure ABGA at the time of 20 min after normal saline inhalation has finished (T2).<br>|
| Experimental: iloprost group<br>iloprost inhalation group | Drug: iloprost inhalation<br>* When anesthesia induction finishes, change patients' position from supine to lateral position and measure ABGA, VBGA while two lung is ventilated (T0). After 20 minutes of applying one-lung ventilation, measure ABGA and VBGA (T1). Apply iloprost inhalation for iloprost group and measure ABGA at the time of 20 min after iloprost inhalation has finished (T2).<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Result of arterial blood gas analysis : partial pressure of oxygen(PaO2) |  | 20 minutes after iloprost inhalation (T2) | 
| Result of arterial blood gas analysis : partial pressure of oxygen in the arterial blood(PaO2)/Fraction of inspired oxygen(FiO2) ratio (P/F ratio) |  | 20 minutes after iloprost inhalation (T2) | 
| Result of arterial blood gas analysis : Oxygen saturation in arterial blood(SaO2) |  | 20 minutes after iloprost inhalation (T2) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| deadspace | Dead space ventilation was calculated with Paco2 and end-tidal carbon dioxide (Etco2) according to the Hardman and Aitkenhead equation [1.14 × (Paco2- Etco2)/Paco2 - 0.005]. | 20 minutes after iloprost inhalation (T2) | 
| intrapulmonary shunt | -Shunt fraction (Qs/Qt) was calculated using the following formula: Qs/Qt = (CcO2-CaO2)/(CcO2-CvO2), (1) -whereby: CaO2 = (PaO2 x 0.0031) + (Hemoglobin x 1.36 x SaO2), (2) CvO2 = (PvO2 x 0.0031) + (Hemoglobin x 1.36 x SvO2), (3) CcO2 = ([FiO2 x (PB - PH2O) - PaCO2/Respiratory quotient] x 0.0031) + (Hemoglobin x 1.36), (4) PB is the barometric pressure (760 mmHg), the PH2O is 47 mmHg | 20 minutes after iloprost inhalation (T2) |