Cardiac, Thoracic and Vascular Anaesthesiology
635
Hypoxemia in sequential one lung ventilation:
oxygen saturation tends to decrease in the
second half rather than in the first half of
ventilation
Ventilation,one-lung
T. Fukushima1, M. Takada1, H. Yamamoto1
1Tokyo Metropolitan Tama Medical Center - Tokyo (Japan)
Background and Goal of Study: Sequential OLV is uncommon, and there are few reports of it to date. At our institution, we perform atrial fibrillation treatment surgery with sequential OLV. We have experienced hundreds of cases of sequential OLV and hypothesized that maintaining oxygenation is more difficult in the second half of the procedure than in the first half.
The goal of this study was to examine hypoxemia in sequential OLV retrospectively.
Materials and Methods: Data were retrospectively collected from the electronic medical records between March 1, 2012 and March 31, 2017. The sequential OLV procedure in these operations is shown Fig.1.
Hypoxemia time, defined as the period with SpO2 less than 90%, 93%, and 96% in each half of the procedure, was calculated. This study was approved by the Tokyo Metropolitan Tama Medical Center’s Institutional Review Board 29-65.
Results and Discussion: One hundred and ninety-nine patients were included. The mean duration of the first and second halves was 56 and 39 minutes, respectively. Hypoxemia time is shown Fig. 2. Hypoxemia time in the second OLV was significantly longer than in the first OLV (p<0.001) for all thresholds. Although the duration of the OLV in the first half was longer than in the second half, hypoxemia time in the second half was longer than in the first half, suggesting that hypoxemia may have been higher in the second half than in the first half.
There are three possible reasons for these results. First, right lung capacity is usually larger. Second, the left lung may not have been expanded fully in the interval. Third, hypoxic pulmonary vasoconstriction of the left lung occurring in the first half may have remained in the second half, making the shunt flow larger in the second half. Conclusion: In sequential OLV, hypoxemia tends to occur in the second half rather than in the first half.

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