A Comparative Evaluation of Propofol and Sevoflurane based Anaesthetic Technique on Peri-Operative parameters of patients undergoing Fess under Hypotensive Anaesthesia

INTRODUCTION: Anaesthesia for Functional endoscopic sinus surgery is a challenging job. The surgeons’ operating field itself is very small and surrounded with mucus membranes. It is imperative for the surgeons to look at a clear surgical field in order to identify the diseased tissue properly. A small amount of blood within the field is enough to occlude the view through the endoscope making things difficult for the surgeon and incomplete removal of the diseased tissue will cause the disease to reoccur. Anaesthesiologists have devised various techniques to prevent this bleeding, of which induced hypotension has stood the test of time. This surgery per se is not a major one by its standards and surgeons recently have been trying to accomplish FESS as a day care surgery. Different anaesthetic techniques using different pharmacological agents have been used to induce controlled hypotension. I have chosen to study and compare the effects of inhalational agent – sevoflurane based anaesthesia and intravenous agent – propofol based anaesthesia in reducing the intra operative blood loss. This study proposes to analyse the anaesthetic challenges of keeping the operating field free of blood through pharmacological therapy. It serves to study whether the traditional inhalational agent based anaesthesia – now sevoflurane anaesthesia in our department scores over propofol based anaesthesia in providing better endoscopic vision for the surgeon. AIM: To evaluate the effect of propofol versus sevoflurane anaesthesia as maintenance anaesthetics on the perioperative parameters of patients undergoing FESS under GA and controlled hypotension technique. The following parameters are compared: 1. Ability to achieve targeted MAP, 2. Hemodynamic stability, 3. Undesirable side effects, 4. Blood loss, 5. Endoscopic vision. MATERIALS AND METHODS: After getting clearance from the ethics committee, the study was formulated as follows. Study Design: A prospective, randomized study Case Definition: Inclusion Criteria: 1. ASA I and II, 2. Patients between ages 16 and 60, 3. Patients undergoing endoscopic sinus surgery, 4. Chronic sinusitis, 5. Sinonasal polyposis. Exclusion Criteria: 1. Hypertensive patients, 2. IHD, 3. History of CVA or TIA, 4. Poor respiratory reserve, 5. Significant hepatic/renal disease, 6. Patient refusal, 7. Hypersensitivity to study drug, 8. Not satisfying inclusion criteria. MATERIALS AND METHODS: 1. A prospective, randomized study. 2. Ethical committee approval. 3. Informed consent. 4. 40 patients posted for endoscopic sinus surgery were drafted if they fulfilled the inclusion criteria. 5. Preoperative evaluation included detailed elicitation of significant history, clinical evaluation. 6. Preoperative investigation included Hb, PCV, BT, CT, RFT, ECG and chest X-ray. 7. Premedication included oral alprazolam 0.5mg 3 hours before surgery. 8. Any relevant specialist opinion, investigation and care were obtained. 9. Nasal packing done with 4% lignocaine with oxymetazoline. 10. In the operation theatre, IV access was obtained with 18G IV cannula. Preloading was done with 10ml/kg of balanced salt solution. 11. Monitoring was done using a L&T monitor which included ECG, NIBP, SpO2 and temperature. 12. After recording baseline values and preloading, patients were given the drug based on the group they were assigned to. 13. Preoxygenation with 100% oxygen for 3 min. 14. Induction : Fentanyl 2mcg/kg + Propofol 2.5 mg/kg + Rocuronium 0.6mg/kg. 15. Endotracheal intubation. 16. Throat packing. 17. In group S, maintenance with 66% N2O, 33% O2, 3% sevoflurane with IPPV and rocuronium as relaxant. 18. In group P, maintenance with 66% N2O, 33% O2, propofol 10mg/kg for initial 10 min, 8mg/kg for next 10 min, 6mg/kg till the end of procedure with IPPV and rocuronium as relaxant. SUMMARY: The prospective randomized study aimed to compare the effects of sevoflurane and propofol as maintenance anaesthetics on peri-operative characteristics of patients undergoing FESS procedure under general anaesthesia and induced hypotensive anaesthetic technique. Important conclusions from this study include 1. Both drugs provide good to excellent conditions during maintenance of anaesthesia. 2. Sevoflurane lowered intra operative blood pressures better than propofol anaesthesia. 3. Propofol produces lower intra operative heart rate than sevoflurane anaesthesia. 4. Sevoflurane anaesthesia causes more incidence of intra operative hypotension than propofol based anaesthesia. 5. Propofol anaesthesia provided better visualization of the surgical field assessed by the surgeon using Fromme Boezzart scale. 6. Propofol based anaesthesia reduces intra operative blood loss compared to sevoflurane anaesthesia. 7. Propofol and sevoflurane based anaesthesia causes easily reversible induced hypotension. It did not extend into the post operative period nor was there any rebound hypertension. 8. A few patients in both sevoflurane and propofol groups require vasodilator nitroglycerine to achieve the target mean arterial pressure. 9. Lack of usage of end tidal agent analyser was a limiting factor in the study. 10. Balanced anaesthesia technique with meticulous attention to patient’s needs is the single most important factor in production of controlled hypotension during surgery with propofol anaesthesia reducing the intra operative blood loss. CONCLUSION: Sevoflurane and propofol based anaesthesia produce comparable and excellent intra-operative conditions during anaesthesia for FESS. Sevoflurane group produced superior blood pressure control, while propofol had lower and more stable heart rates. Propofol based anaesthesia had lesser intra operative blood loss and provided better visualization