Complications during general anesthesia,induction period: difficult airway, hypotension, upper airway obstruction, laryngospasm, pulmonary aspiration Maintenance period: hypotension, hypertension, awareness, bronchospasm, pulmonary aspiration.

Emergence period: delayed emergence, upper airway obstruction, pulmonary aspiration.

Pulmonary aspiration occur all ranges of general anesthesia. Because the patients can not protected themselves due to anesthetic medication, example: volatile agent, opioid.This can cause decrease consciousness, delayed gastric emptying time. Incidence of pulmonary aspiration was 1 : 900 - 1 : 10,000 of general of anesthesia (induction 20%, emergence 80%), Anesthesia Service in Siriraj Hospital (2017) 6: 25,000 case Pathophysiology of pulmonary aspiration.

Pulmonary aspiration is defined as inhalation of oropharynx or stomach contents through the larynx to low respiratory tract. Aspiration pneumonitis is the inflammation of the lung caused by aspirating or inhaling irritants (Mendelson's syndrome).

Gastric acid is a digestive fluid formed in the stomach and is composed of hydrochloric acid, potassium chloride, and sodium chloride.The highest concentration of gastric acid is 140-160 mEq/L. The pH of gastric acid is 1.5-3.5 in the human stomach lumen.

Risk factors for increased gastric contents: full stomach, delayed gastric emptying, incompetent lower esophageal sphincter, lithotomy position, laparoscopy, length of surgery more than 2 hr., difficult airway.

This study observed Volume and pH of Gastric Contents in Patients undergoing Gynecologic Laparoscopic Surgery during Emergence from General Anesthesia.

The study was approved from the Siriraj Institutional Review Board (Si-IRB), COA (Certificate of Analysis):Si437/2018 and was written informed consent was obtained from all subjects. The study was conducted at the Department of Siriraj Obstetrics and Gynecology.

A total of 100 patients were enrolled in the study between September 2018 and 2019. All patients underwent general anesthesia for elective gynecologic laparoscopic surgery. Inclusion criteria were elective Cases, laparoscopic surgery, age 18-65 year,BMI<30kg/sq.m. Exclusion criteria were emergency Case, full stomach. Withdrawal or termination criterion was the difficult inserted orogastric tube.

On the day of surgery, participants signed the informed consent. Record data consisted of NPO time, premedication drug, BMI, having intravenous fluid. All patients underwent general anesthesia after application of standard monitors, anesthesia was induced with fentanyl 1-2 mcg/kg. or morphine 0.1-0.2 mg/kg., propofol 1.5-2.5 mg/kg.,nimbex 1-1.5 mg/kg or atracurium 0.6 mg/kg. Anesthesia was maintained with sevoflurane, air, o2.

Gastric volume and PH were measured with PH meter, measured at 1hr. intervals until the end of surgery. Intraoperative, record medication for reduced gastric volume or PH.

Postoperative, data were record nausea or vomiting, medication requirements.

Inclusion Criteria:

• ASA class 1-2,
• 18-65 years old,
• Laparoscopic surgery,
• BMI<30kg/sq.m.

Exclusion Criteria:

• Difficult inserted orogastric tube.

All patients underwent gynecologic laparoscopic surgery.