Prophylaxis for Aspiration of Gastric Contents.

(This description is for one drug and similar for other drugs) We repacked the placebo, lansoprazole 15 mg and lansoprazole 15 mg plus domperidone 10 mg in 180 envelopes (times two) and then two envelope in one envelope each for evening and morning of the same size, shape and color and their name were changed as drug one, drug two and drug three by a person who was not taking part in the study to the patients (single-blind) and investigators (double-blind) blinded of it. The group assign paper was sealed in another envelope that was opened to know which drug corresponds to either drug one or drug two or drug three after the statistical analysis(triple-blind).

On the preoperative anaesthesia visit, a day before surgery, the nature and purpose of the study was explained to each patient. We asked each patient to pick up on one envelop from the envelopes (randomization). Thus the patients were allocated to either Group C (control), Group L lansoprazole 15 mg or Group LD lansoprazole 15 mg with domperidone 10 mg randomly by sealed envelope method. Age, sex, ASA physical status, weight, height, BMI and the study drug given were recorded for each patient. All patients also received tablet diazepam 5 mg with study drugs. These drugs were given orally with 20 ml of drinking water at 8:00 p.m. in the evening day before surgery and 6:00 a.m. morning on the day of surgery. According to the hospital policy, all patients were fasted from 12:00 midnight. Upon arrival in the receiving area of the operating room. All patients were asked if they had been aware of any unusual feeling (side effect) after taking the study drug.

In the operating room, routine monitors were attached to the patients and turned on. After pre-oxygenation with 100% O2 by face mask using eight breaths vital capacity method, anaesthesia was induced with injection fentanyl 1-2 mcg/kg, propofol 2-3 mg/kg and rocuronium 0.6-0.9 mg/kg. Lungs were ventilated taking care not to inflate the stomach. Maintaining cricoid pressure trachea was intubated with cuffed endotracheal tube. Placement and position was confirmed with EtCO2 monitor and then secured properly. After establishing stable anaesthesia, an endotracheal tube sized 8.5 internal diameter was passed via oral route in the esophagus with anterior displacement of larynx. A predetermined length marked with adhesive tape (xiphoid process to ear lobule- fro ear lobule to nasal tip) of stomach tube sized 18 F was passed through the esophageally placed endotracheal tube. Placement of this tube within the stomach was verified with auscultation over the epigastrium during insufflation of 10-15 ml of air. Gastric contents were gently aspirated manually with 60 ml syringe by an investigator who was blind of group assignment. Applying manual pressure over the epigastrium while the patient was in supine and then left and right lateral positions, gastric tube was then manipulated to ensure maximum emptying of gastric contents. The stomach tube was then removed followed by esophageally placed endotracheal tube. Any problem encountered during inserting or removing the oro-esophageally placed endotracheal tube or gastric tube was also recorded. The volume of gastric contents was measured with graduated syringe and pH using pH meter. The pH meter was calibrated using standard buffers at pH values of 4, 7 and 9.20. This pH meter has a precision of 0.01 units over the entire pH range. A minimum of one-millimeter volume of gastric contents was sufficient for pH determination with pH meter. In case of very little amount of gastric contents, we cut the stomach tube and aspirated gastric material with disposable plastic pipette. Samples less than one-millimeter were considered as no gastric contents because a minimum of one- millimeter of gastric contents was sufficient for pH- metry. Using bile salts as marker for bile, we applied qualitative Hay's sulphur test for the presence of bile salts. A minimum volume of one millimeter of gastric contents was adequate to perform Hay's sulphur test. In this test finely powered sulphur is sprinkled on the surface of cool (17 OC or below) liquid. If bile salts are present sulphur sinks down, sooner or later, in accordance with their percentage. If bile salts are present in from 1:5,000 (0.02%or 200 mcg/ml to 1:10,000 (0.01% or 100 mcg/ml) sulphur at once begins to sink and all precipitated in two or three minutes; even in dilution of 1:120,000 (0.0008% or 8.33 mcg/ml precipitation occurs. On the other hand, if sulphur remains floating on the surface, bile salts are absent.

Anaesthesia was maintained with air, O2 and sevoflorane. Patients also received incremental doses of fentanyl and rocuronium as required. At the end of surgery, injection atropine and neostigmine were given to antagonize the residual effect of rocuronium. All patients were extubated in lateral position and then transferred to recovery room.

Time since premedication T1 (time from evening dose till aspiration of gastric contents) and Time since premedicationT2 (time from morning dose till aspiration of gastric contents), pH, volume of gastric contents and results of Hay's sulphur test were also recorded for all patients.

Statistical test were performed using GraphPad Software, Inc., San Diego, United States and results are expressed as absolute values or mean ± standard deviation SD (SEM). Statistical analysis between the groups were carried out using analysis of variance (ANOVA) for age, BMI, time since premedication T1, time since NPO and T2 , pH and volume. Chi square test was applied for sex, ASA physical status, Hay's test and risk of aspiration according to criteria defined (pH ≤ 2.5 and volume ≥ 0.4ml/kg or 25 ml. Post hoc tests with Bonferrni correction applied where p-value significant(p <0,05). A p-value of less than 0.05 was considered statistically significant. Power analysis revealed that the sample size (n= 30) in each group was of the study was sufficient to detect a difference of 0.7 among the groups in gastric pH and volume at a significant level of 0.05 (=α 0 with a power of 0.85.