The Effects of Pharyngeal Packing on the Postoperative Gastric Fluid Volume in Patients Undergoing Functional Endoscopic Nasal Surgery

Following approval from the Ethics and Research Committee of the anesthesia department, Faculty of Medicine, Cairo University, and obtaining written informed consent from all participating patients meeting the inclusion criteria; patients will be randomly assigned into two groups using a computer-generated random number list with a closed-sealed envelope.

• Group (P): will include the patients who will receive pharyngeal packing
• Group (C): will include the patients who will not receive pharyngeal packing The day before the operation, all patients should be instructed to follow institutional fasting guidelines (a minimum of 2 h for clear fluids, 6 h for a light meal, and 8 h for a meal that included fried or fatty food) On operation day,The patient will attend at the pre-anesthesia room 1 hour before the procedure. A 20 Gauge cannula will be inserted peripherally.

Prophylactic antiemetic (metoclopramide 0.15mg/ kg) will be given slowly intravenously as premedication.

Then a serial ultrasonographic qualitative and quantitative assessment of the gastric antrum of the patients will be done and recorded preoperatively by the anesthetist who will be blinded to the study groups.

A preoperative ultrasonographic examination of the gastric antrum (at the sagittal plane between the left lobe of the liver and pancreas at the level of the aorta) will be performed in the right lateral decubitus position

Ultrasound Assessments:

A standardized scanning technique will be used with a portable sonographic system equipped with a 5- to 2-MHz curved array transducer (GE HealthCare). Subjects will be first placed in the supine position and then in the right lateral decubitus (RLD) position, always in a 45°semirecumbent position. In both of these positions, fluid or semifluid content gravitates preferentially to the antrum, and air or gas is displaced proximally toward the body or fundus, thus facilitating antral sonography (8) During ultrasound imaging, the gastric antrum will be identified in the sagittal to right parasagittal plane using the left lobe of the liver, the pancreas, abdominal aorta, or inferior vena cava as anatomical landmarks. The ultrasonographic assessment will consist of a qualitative and quantitative evaluation of the gastric antrum. The qualitative assessment is aimed at the nature of gastric content (empty, fluid, or solid content). Based exclusively on this qualitative assessment of the antrum, and once the presence of solid content will be ruled out, patients will be classified into 3 grades (12)

• Grade 0 antrum: is defined as the absence of fluid content in both supine and RLD positions, suggesting a "completely empty" state.
• Grade 1 antrum: If fluid content is observed only in the RLD position, but not in the supine position. It correlates with low-volume states compatible with baseline gastric secretions in fasted patients.
• Grade 2 antrum: If fluid is observed in both supine and RLD. The quantitative assessment of the gastric volume will be performed by measuring the cross-sectional area (CSA) of the gastric antrum (antral CSA) between peristaltic contractions, using the free-tracing calibre of the ultrasound unit. This free-tracing method is equivalent to the 2-diameter method of area measurement, and it is simpler and highly reproducible. This validated method allows rapid point-of-care assessment at the bedside, which is relevant for clinical practice (13) Using GE ultrasonography

Then gastric volume will be calculated using the following equation:

Volume (ml) = 27 + 14.6 x Right lateral CSA (cm2

) - 1.28 x age (year) Where Right-lat CSA is the antral CSA measured in the right lateral decubitus. In the operative room, standard monitoring (electrocardiography, pulse oximetry, non-invasive blood pressure, and capnography after intubation) will be applied to the patient.

General Anesthesia (GA) will be induced by another anesthetist who will open the closed envelope and not be blinded to the study groups with intravenous propofol 2 mg/kg, fentanyl 2 mcg/kg, atracurium 0.5 mg/kg, and the trachea will be intubated after mask ventilation for 3 minutes.

Anesthesia will be maintained with IPPV, isoflurane (MAC 1-1.5) in oxygen/air and atracurium 0.1mg/kg as a neuromuscular blocker by the time every 20 minutes. Ventilation will be controlled to maintain an end-tidal CO2 at 30 -35 mmHg.

Following the orotracheal intubation, soft wet pharyngeal packs were placed with gentle maneuvers to avoid damage to the soft palate in patients in group (P). The end of the pharyngeal pack will be hidden inside the mouth of the patient. Patients in both groups were intravenously administered ranitidine (0.5 mg/kg) following the intubation, and ketorolac (30 mg) and pethidine (0.5 mg/kg) at the end of the operation for postoperative analgesia.

Gastric ultrasonographic evaluation will be done at the end of the operation by the same anesthetist who will be blinded to the study group as described before, and the pharyngeal packs of the patients in group(P) will be removed, the residual neuromuscular block will be antagonized with atropine 0.01 m/kg and neostigmine 0.05mg/kg and extubation and suction under vision will be done.