A Comparison of Effects of Propofol and Isoflurane on Arterial Oxygenation Pressure, Mean Arterial Pressure and Heart Rate Variations Following One-Lung Ventilation in Thoracic Surgeries

BACKGROUND Hypoxia occurs during one-lung ventilation (OLV) due to the arteriovenous shunt of unsaturated pulmonary venous blood. Hypoxic pulmonary vasoconstriction (HPV) acts as a defense mechanism against shunting. In thoracic surgery, anesthetics with minimal inhibitory effect on HPV and minimal hemodynamic changes are preferred. OBJECTIVES The present study aimed to evaluate the effects of propofol and isoflurane on patients' arterial oxygen pressure following one-lung ventilation during thoracic surgeries. MATERIALS AND METHODS In this randomized clinical trial study which was conducted in Iran, sixty patients with ASA (The American Society of Anesthesiologists) class I & II who were candidates for right elective thoracotomy were divided in two groups. Induction of anesthesia in the two groups was conducted using the same method, and left double-lumen endotracheal tube was inserted. In the first group propofol was used for the maintenance of anesthesia, and isoflurane for the second group. During two-lung ventilation and at minutes 5 and 10 after OLV, ABG (arterial blood gas) (for detecting the mean pressure of arterial oxygen), mean arterial pressure and heart rate were recorded. RESULTS Sixty patients (mean age = 4124.18 ± 18.63 years) were divided into two groups. The age and gender of the subjects were not statistically different between the two groups. In the propofol group, the arterial oxygen pressure during two-lung ventilation and at 5th and 10th minutes after OLV was 263.14 ± 136.19, 217.40 ± 133.99 and 182.34 ± 122.39; in the isoflurane group, it was reported as 206.29 ± 135.59, 164.78 ± 118.90 and 155.35 ± 109.21 mmHg, respectively. In the propofol group, mean arterial pressure during two-lung ventilation, and 5th and 10th minutes after OLV, was 84.01 ± 20.67, 88.15 ± 20.23 and 86.10 ± 19.13, respectively; regarding the isoflurane group, it was reported as 79.66 ± 17.04, 84.78 ± 20.19 and 86.50 ± 17.07 mmHg, respectively. In the propofol group, heart rate during two-lung ventilation, and 5th and 10th minutes after OLV was 92.77 ± 17.20, 94.0 ± 18.34 and 94.33 ± 21.03, respectively; In the isoflurane group, it was reported as 92.87 ± 16.96, 91.8 ± 18.75 and 91.05 ± 17.20 min, respectively. These values were statistically similar in the two study groups. CONCLUSIONS The effects of propofol on hemodynamics and arterial oxygen pressure during one- or two-lung ventilation were not different from those of isoflurane.