Abstract

The risk of developing hypoxaemia remains a major concern when the use of one-lung anaesthesia (OLA) is considered for thoracic surgery) Several factors such as hypoxic pulmonary vasoconstriction (HPV), lung collapse and gravity are known to ameliorate the decrease in arterial oxygen tension (PaO2) which occurs during OLA. However, the factors which determine whether an individual patient will develop clinically important arterial oxygen desaturation during OLA have remained unclear. Materials and Methods: A cross-sectional study was conducted among 68 patients who came for lung or non-lung surgery in the Department of Anaesthesia, Govt General and Chest Hospital, Erragadda, Hyderabad during a period of two years. All the ASA grade I and II patients who needed One Lung Anaesthesia (OLA) during the study period either for lung or non-lung surgery were included in this study. The exclusion criteria were patients less than 15 years, presence of cardiovascular disease, anticipated difficult intubation and inability to isolate the lungs properly after double lumen tube insertion. On the patient arrival in the operating room peripheral and central intravenous cannulations and percutaneous arterial line insertion were done under local anaesthesia. Blood samples for preoperative PaO2, PaO2 during two lung ventilation (TLV), PaO2 at 10 mins and 25 mins. After starting OLA were taken and assessed. Results: Total number of patients in this study were 68. Out of this 44 (64.7%) were males and 24 (35.29%) were females. Patients undergone right thoracotomy was 26 (38.23%) and left thoracotomy was 42 (61.76%). Among the 68 patients 48 (70.59%) underwent lung surgery, while 20 (29.41%) underwent non-lung surgery. Mean PaO2 at different stages of surgery is described in Table No. 1. Table No. 2 shows that there is a significant increase in the PaO2 at 25 minutes in patients who had their left lung collapsed during surgery. Under the same conditions, PaO2 with the right lung collapsed shows a drop. In Table No. 3 non-smokers showed a lower PaO2 at 25 minutes of one lung ventilation when compared to smokers. The females in the study showed a significantly higher PaO2 at 25 minutes of one lung ventilation. Conclusion: Our study was an attempt to show that it is possible to predict preoperatively the patient who is likely to suffer from hypoxaemia during OLA. The ability to predict the subsequent arterial oxygenation allows the anaesthetists/surgeons to assess and rationalize risk/benefits regarding the use of OLA during thoracic surgery and permits more controlled intraoperative management of oxygenation.

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