The effect of gradual transition to one lung ventilation on oxygenation in rats

This experimental study investigated the effects of gradual transition to one lung ventilation on oxygenation and intrapulmonary shunt ratio in rats.Fourteen female (200-250gr) Wistar-Albino rats were divided into two groups as Classical Transition Group (CTG, n=7) and Gradual Transition Group (GTG, n=7). Two lung ventilation (TLV, TV;8 mL/kg, RR;60/min, FiO2;1.0) was applied for fifteen minutes after the induction of anesthesia, performing arterial and venous cannulation and tracheostomy. At the end of the stabilization period, one lung ventilation (OLV, TV;6 mL/kg, RR;80/min, FiO2;1.0) was applied for fifteen minutes in CTG and sequential one minute OLV one minute TLV, one minute OLV one minute TLV and fiftteen minute OLV were applied in GTG. Hemodynamic values and arterial blood samples were obtained and noninvasive intrapulmonary shunt ratio was calculated at the end of the stabilization period, at the fifth and fiftteenth minutes of OLV. Data were given as mean ±SEM or % value±SEM. Mann-Whitney U test and Wilcoxon signed-rank test were performed for stastitical analysis and a value of p<0.05 was considered significant.There was no statistical significance between the groups in regard to MAP and HR at the end of the stabilization period, at the fifth and fiftteenth minutes of OLV (p>0.05, p>0.05,respectively). PaO2, PaCO2 and shunt ratio values were respectively determined as 152.3±34.5 mm Hg, 31.9±2.7 mm Hg, % 5.2±1.4 at the end of the stabilization period, 60.1±3.7 mm Hg, 50.0±5.9 mm Hg, % 10.2±0.7 at the fifth minute of OLV and 61.1±5.4 mm Hg, 56.7±9.9mm Hg, % 10.2±1.0 at the fifteennth minute of OLV for CTG. PaO2, PaCO2 and shunt ratio values were respectively determined as 243.5±24.8 mm Hg, 38.1±2.3 mm Hg, % 1.9±0.2 at the end of the stabilization period, 68.8±6.4 mm Hg, 49.1±6.1 mm Hg, % 9.1±0.8 at the fifth minute of OLV and 69.9±5.2 mm Hg, 50.6±4.8 mm Hg, % 8.8±0.8 at the fifteennth minute of OLV for GTG.No statistically significant difference was found between the groups in regard to PaO2, PaCO2 and shunt ratio values at the end of the stabilization period (p>0.05, p>0.05, p>0.05, respectively), at the fifth minute of OLV (p>0.05, p>0.05, p>0.05, respectively) and at the fiftteenth minute of OLV (p>0.05, p>0.05, p>0.05, respectively).It is observed that gradual transition to OLV in rats does not have favorable effects on oxygenation in the form of PaO2 increase and intrapulmonary shunt ratio decrease when compared to classical transition.