Effect of low-flow anesthesia on postoperative agitation in rhinoplasteries

Aim: In our study, we aimed to compare the incidence of postoperative agitation with the high flow anesthesia technique in patients who will undergo rhinoplasty surgery in which low flow anesthesia technique is applied. Material and Method: This study was carried out in a total of 76 ASA I-II patients aged 18-50 years who were scheduled for elective rhinoplasty surgery under general anesthesia in İnönü University Medical Faculty Hospital after the Malatya Clinical Research Ethics Committee approval (protocol no: 2022/84) and written informed consent from the patients. The study was planned as double-blind. The patients who participated in the study and the person who evaluated the agitation in the postoperative period did not know the fresh gas flow rate applied. The cases followed with a fresh gas flow rate of 2 L/min were named Group Y (n=38), and the cases followed with a fresh gas flow rate of 0.5 L/min were named Group D (n=38). In both groups, anesthesia was induced with 2 mg/kg propofol and 1 µg/kg fentanyl as standard. 0.6 mg/kg rocuronium was administered to facilitate endotracheal intubation. Female patients were intubated with 7.5 endotracheal tubes and male patients with 8. 500 mL of low flow was applied in Group D AGC mode. 2 lt flow was applied in Group Y AGC mode. AGC also allows the user to select 1 of 9 different rates at which the target sevoflurane value can be reached. (9 is the highest speed) AGC mode was applied to both groups at level 6 speed. Anesthesia depth was adjusted so that the BIS value was between 40 and 60. All patients underwent local anesthetic infiltration (2% lidocaine HCL +1.100.000 epinephrine by the surgeon at the operating site to control bleeding and pain). Intravenous 0.05-0.2 µg/kg/min remifentanil infusion was administered to all patients as an analgesic. Mechanical intilation settings in volume controlled mode tidal volume; 6-8 ml/kg, frequency; Ventilation was provided by setting 10–12/min, end tidal carbon dioxide value 35–40 mmHg, PEEP (positive end-expiratory pressure) 5 cmH2O, and oxygen given to the patient > 40% (oxygen-air mixture) (Maquet Flow-I®). Tramadol 1 mg/kg was administered intravenously for postoperative analgesia 20 minutes before the end of the operation. At the end of the surgery, a silicone doyle nasal splint and an external nasal thermoplastic splint were placed in the bilateral nasal cavity for external nasal protection. At the end of the surgery, AGC mode was exited and switched to manual control mode in both groups. In both groups, the vaporizer was turned off and 100% O2 was given. The flow of both groups was 6 lt. Waking was done with high current. The fresh gas flow was increased to 6 L/min. At the end of the surgery, neuromuscular block was antagonized with neostigmine-atropine and confirmed with TOF monitor. Sedation and agitation were assessed immediately after extubation using the following 2 scales: the Ramsey Sedation Scale (RSS) and the Richmond Agitation-Sedation Scale (RASS). RASS is divided into 10 levels (score range, -5 to 4, higher scores indicate more agitation) RSS is divided into 6 levels (score range, 1-6, lower scores indicate more agitation). Agitation scores were evaluated after the patient was extubated by independent anesthesiologists blinded to the anesthetic methods used in this study. The patients were observed for 30 minutes in the post-anesthesia care unit. Pain intensity was assessed by a well-trained nurse blinded to the randomized study group using the Numerical Rating Scale (NRS, range, 0-10, higher scores indicate worse pain) immediately after arrival at the postoperative care unit, at 15 and 30 minutes. Rescue analgesics such as nonsteroidal anti-inflammatory drugs and opioids were administered when NRS exceeded 5. Intraoperative mean arterial blood pressure (MAP), heart rate and SpO2 were recorded for the first 15 minutes after intubation and 10 minutes after extubation. The total amount of remifentanil and sevoflurane used was recorded. The amount of bleeding, the quality of the surgical field in terms of bleeding (Boezaart score), and the satisfaction of the surgeon in terms of bleeding during the operation (Likert scale) were evaluated. Participating surgeons rated surgical site visibility from 0 to 5 on the Boezaart rating scale, with 0 being the best and 5 the worst. Surgeon satisfaction with the operative field was rated at the end of surgery using a 5-choice Likert scale: 1 = very bad, 2 = bad, 3 = fair, 4 = good, and 5 = excellent. Results: The RSS score of the high flow group was significantly lower than the low flow group, and the RASS score of the high flow group was significantly higher than the low flow group. The amount of bleeding in the high flow group is higher than the low flow group. There was no difference between the two groups in terms of postoperative nausea-vomiting, cough, desaturation, chills, pruritus, urticaria, and laryngospasm. Conclusion: In our study, low flow anesthesia application reduced the incidence of agitation and the amount of intraoperative bleeding in the recovery period of patients undergoing rhinoplasty surgery. Keywords: Anesthesia, Emergence agitation, Rhinoplasti