Effect of One-Lung Ventilation on Blood Sevoflurane and Desflurane Concentrations.

Objective: To determine the blood sevoflurane and desflurane concentrations during one-lung ventilation (OLV).
Design: Randomized, single-blind study.
Setting: Single university hospital.
Participants: The study comprised 24 patients, 35 to 70 years old who were scheduled for either a major abdominal surgery or thoracotomy.
Interventions: The patients were divided into the following 4 groups: sevoflurane two-lung ventilation (TLV), sevoflurane OLV, desflurane TLV, and desflurane OLV. Vaporizers were set at 1.5% sevoflurane or 6% desflurane.
Measurements and Main Results: In the TLV groups, blood samples were taken in 10-minute intervals starting 40 minutes after the start of TLV (T ₁ -T ₉ ) for blood gas analysis and gas chromatography. In the OLV groups, the first sample was collected at 40 minutes of TLV (T ₁ ), and other samples were collected in 10-minute intervals from the start of OLV (T ₂ -T ₉ ). Saturation of peripheral oxygen (SpO ₂ ), hemodynamic variables, and inspired and end-tidal volatiles were recorded. The fraction uptake of the volatile agents (F) was calculated for each patient at the same time points. The mean arterial sevoflurane concentration in the sevoflurane OLV group at T ₁ decreased from 40.7 ± 4.4 to 30.2 ± 2.5 µg/mL at T ₃ (p = 0.014, 26% decrease). In the OLV desflurane group, the mean arterial desflurane concentration at T ₁ declined from 224.6 ± 44.8 to 159.8 ± 32 µg/mL at T ₃ (p=0.018, 29% decrease). However, the reduction of sevoflurane concentration compared with that of desflurane at T ₃ was not statistically significant (p = 0.31). In addition, the fraction uptake of the volatile agents values significantly increased at the start of OLV (p = 0.001).
Conclusion: An OLV procedure causes a decrease in the both arterial and venous blood concentrations of sevoflurane and desflurane. This reduction is believed to be due to ventilation-perfusion mismatch.
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