218 METHODS FOR THE ANALYSIS OF GASTRIC JUICE 



fifteen minutes from the time the test meal is eaten until the 

 stomach is empty 5 to 6 c.c. samples of gastric contents are with- 

 drawn from the stomach by means of aspiration. 



In the removal of samples from the stomach, it is essential 

 that very little traction be employed. To completely empty the 

 stomach, aspiration is practiced in four positions: (a) on the back; 

 (6) on the stomach; (c) on right side; (d) on left side. This results 

 in complete evacuation of the stomach. Three tests may be 

 employed to determine whether the stomach is empty: (1) No 

 more material can be aspirated in any position; (2) injection of 

 air and auscultation over the stomach with a stethoscope reveals 

 a sticky rale and not a series of gurgling rales such as is heard 

 when there is material in the stomach; (3) lavage or irrigation 

 through the tube which shows the absence of all food in the 

 stomach. 



6. Examination of the Samples. The old methods of gastric 

 analysis involved the collection (by analysis and calculation) of 

 data regarding several types of acidity. The modern tendency 

 among clinicians is to lay particular emphasis upon the values for 

 total acidity and free acidity. The determination of the peptic 

 activity is also important as well as the demonstration of the 

 presence or absence of occult blood, lactic acid, mucus, food rests, 

 etc. 



Procedure. Strain each sample through a fine-mesh cheese 

 cloth. 1 Examine the residue for mucus, blood, and food rests. 

 Use the strained stomach contents for the determination of total 

 acidity, free acidity and peptic activity by methods which 

 follow. 



(a) Determination of Total Acidity. Principle. The indicator 

 used is phenolphthalein. Since the indicator reacts with mineral 

 acid, organic acid, combined acid and acid salts the values obtained 

 represent the total acidity of the solution. 



Procedure. Measure 1 c.c. of the strained stomach contents 

 by means of an Ostwald pipette and introduce it into a low-form 

 60 c.c. porcelain evaporating dish. Dilute with 15 c.c. of distilled 

 water. Add 2 drops of a 1 per cent alcoholic solution of phenol- 

 phthalein and titrate with N/100 sodium hydroxide until a faint 



1 The examination for microscopical constituents should be made on the 

 original (unstrained) gastric contents. Tests for occult blood may be made 

 on the sediment if desired. 



