High inspired oxygen concentrations (FiO₂) are commonly administered during general anesthesia to prevent hypoxemia. However, excessive oxygen administration may result in hyperoxemia, which has been associated with impaired hypoxic pulmonary vasoconstriction, increased oxidative stress, ventilation-perfusion mismatch, and postoperative pulmonary complications. During one-lung ventilation (OLV) for thoracic surgery, higher FiO₂ is often required because of increased intrapulmonary shunting, making hyperoxemia a frequent occurrence. The Oxygen Reserve Index (ORI) is a noninvasive pulse oximetry-derived parameter that reflects moderate hyperoxemia (PaO₂ approximately 100-200 mmHg) and may facilitate more precise oxygen titration than pulse oximetry alone.
This prospective, randomized, assessor-blinded clinical trial aims to determine whether FiO₂ titration guided by both ORI and peripheral oxygen saturation (SpO₂) reduces the incidence of hyperoxemia compared with conventional SpO₂-guided FiO₂ titration during OLV in patients undergoing thoracic surgery. Participants will be randomly assigned to either an ORI-guided group or a conventional SpO₂-guided group. The primary outcome is the incidence of hyperoxemia (PaO₂ \>125 mmHg) after OLV. Secondary outcomes include SpO₂, ORI, PaO₂, and FiO₂ measured
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
QUADRUPLE
Enrollment
58
During one-lung ventilation, FiO₂ is adjusted according to both ORI and SpO₂. FiO₂ is titrated to maintain SpO₂ ≥98% while keeping ORI above 0 to minimize hyperoxemia.
During one-lung ventilation, FiO₂ is adjusted according to SpO₂ alone. FiO₂ is titrated to maintain SpO₂ ≥98% according to the institutional standard of care.
Konkuk University Medical Center
Seoul, Gwangjin-gu, South Korea
Incidence of hyperoxemia during one-lung ventilation
Hyperoxemia is defined as an arterial partial pressure of oxygen (PaO₂) greater than 125 mmHg measured after initiation of one-lung ventilation.
Time frame: 10 min after initiation of one-lung ventilation during operation
Peripheral oxygen saturation (SpO₂)
Peripheral oxygen saturation
Time frame: 10 mins after two-lung ventilation, 10 mins after initiation of one-lung ventilation, and 10 mins after resumption of two-lung ventilation, all time frames are included in anesthesia time
Oxygen Reserve Index (ORI)
Oxygen Reserve Index measured during anesthesia.
Time frame: 10 mins after two-lung ventilation, 10 mins after initiation of one-lung ventilation, and 10 mins after resumption of two-lung ventilation, all time frames are included in anesthesia time
Arterial oxygen tension (PaO₂)
Arterial partial pressure of oxygen measured by arterial blood gas analysis.
Time frame: 10 mins after two-lung ventilation, 10 mins after initiation of one-lung ventilation, and 10 mins after resumption of two-lung ventilation, all time frames are included in anesthesia time
Fraction of inspired oxygen (FiO₂)
Fraction of inspired oxygen administered during anesthesia.
Time frame: 10 mins after two-lung ventilation, 10 mins after initiation of one-lung ventilation, and 10 mins after resumption of two-lung ventilation, all time frames are included in anesthesia time
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