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Year : 2007  |  Volume : 51  |  Issue : 2  |  Page : 117 Table of Contents     

A comparative study of volume and pH of gastric fluid after ingestion of water and sugar-containing clear fluid in children

1 D.A., M.D., Department of Anaesthesiology, Govt. Medical College, Surat, India
2 D.A., M.D., Prof., Department of Anaesthesiology, Govt. Medical College, Surat, India

Date of Acceptance25-Jan-2007
Date of Web Publication20-Mar-2010

Correspondence Address:
Gojendra Rajkumar
Regional Institute Of Medical Sciences, Imphal - 795001
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Source of Support: None, Conflict of Interest: None

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A prospective randomised study on 90 children aged 1-10 year was undertaken to evaluate and compare the gastric fluid volume and pH following ingestion of water and sugar-containing clear fluid given at 2, 4 and 8 hours before elective surgery. Although not diminishing the risk of aspiration, 2mlkg-1 body wt. of clear fluids given 2 hours before surgery appear to add no additional risk for aspiration of gastric contents and it may also alleviate the unpleasant pre-operative experience due to prolonged fast.

Keywords: Paediatric patients, Pre-operative fasting : Gastric volume; pH

How to cite this article:
Rajkumar G, Mehta M K. A comparative study of volume and pH of gastric fluid after ingestion of water and sugar-containing clear fluid in children. Indian J Anaesth 2007;51:117

How to cite this URL:
Rajkumar G, Mehta M K. A comparative study of volume and pH of gastric fluid after ingestion of water and sugar-containing clear fluid in children. Indian J Anaesth [serial online] 2007 [cited 2021 Apr 11];51:117. Available from: https://www.ijaweb.org/text.asp?2007/51/2/117/61125

   Introduction Top

Pre-operative fasting is considered a mandatory pre-requisite for elective surgery to minimize both the risk of regurgitation and vomiting, and the severity of pnuemonitis should gastric fluid aspiration occur. It is also often an unpleasant experience for children. As many young children go to bed at 19:00 hours, the common instruction of "starve from midnight" implies that they are likely to be fasted for 10 -12 hours even if they are first on the operating list. It is not surprising, therefore, that many children appear irritable, presumably due to hunger or thirst, prior to operation.

A simple approach such as optimizing the duration of fast prior to surgery may reduce the potential toxicity of gastric contents and also make the wait for surgery less stressful. Besides, it avoids pharmacological measures which are not without risk and have known potential adverse effects. Reviews and recent studies [1],[2],[3],[4] have encouraged a shift from the standard 'nil-by-mouth from midnight' fasting policy to more relaxed regimens and have also indicated a reliable gastric emptying within 2 hours suggesting that, particularly for limited intake of clear fluids up-to 2 hours pre-operatively, there would be no increased risk for the patient. Practice has been slow to change due to questions relating to duration of a total fast, the type and amount of intake permitted. The present study was undertaken to assess and compare the effects of 2 hours fasting with that of 4 hours or 8 hours fasting regimens.

   Material and methods Top

Children with gastro-intestinal diseases and those taking medications known to affect gastric fluid composition or gastric emptying were excluded from the study. Following the hospital ethical committee approval, 90 children aged 1 - 10 years (ASA grade-I or II) of either sex scheduled for elective surgical procedures were included in this prospective randomised study. Informed consent was obtained from the parents and all the children were randomly allocated into the following six groups of 15 children each.

Group I -Patients were given 2 mlkg-1 water 2 hours prior to surgery.

Group II -Patients were given 2 mlkg-1 S.C.C.F * 2 hours prior to surgery.

Group III -Patients were given 2 mlkg-1 water 4 hours prior to surgery.

Group IV -Patients were given 2 mlkg-1 S.C.C.F. * 4 hours prior to surgery.

Group V - Patients were given 2 mlkg-1 water 8 hours prior to surgery.

Group VI -Patients were given 2 mlkg-1 S.C.C.F * 8 hours prior to surgery.

* S.C.C.F. Sugar-containing clear fluids

All patients abstained from milk or solid foods from 10.00 pm on the night before surgery. S.C.C.F. * used in this study was analysed as having a pH of 4.0 and osmolarity of 538.48 mOsm /L. [5]

Prior to anaesthesia, all the children were observed for the presence of anxiety, thirst and hunger. Each child was labelled as either anxious or comfortable. The term anxious meant that the child was obviously nervous and uncomfortable with events about him. Comfortable meant that there was no overt signs of anxiety such as crying, agitation, clinging to parents or refusing to talk.

All the patients were premedicated as follows :

Syrup trimeprazine tartrate 4 mgkg-1 orally one hour and injection glycopyrrolate 0.008 mgkg-1 intra-muscular 30 minutes before surgery if patient was below 2 years of age.

Injection pentazocine 0.5 mgkg -1 and injection glycopyrrolate 0.004 mgkg-1 intra-muscular 30 minutes before surgery if patient was above 2 years of age.

Standard perianaesthetic protocol with general anaesthesia was followed. In all the children, induction of general anaesthesia was done either with intravenous thiopentone followed by succinylcholine and tracheal intubation, or with halothane and tracheal intubation. For maintenance of anaesthesia, either nitrous oxide, oxygen and halothane/isoflurane or nitrous oxide, oxygen, pancuronium and halothane (0.5%)/ isoflurane (0.6%) intermittently were used. When pancuronium was used, the patients were reversed with injection neostigmine and injection glycopyrrolate.

A well lubricated, proper sized Ryle's tube was introduced immediately after induction of anaesthesia and its position verified by auscultation of insufflated air over epigastrium. Gastric contents were aspirated using a 20 ml. glass syringe with the child in the supine as well as in the right and left lateral position while applying manual pressure over the epigastrium for maximum recovery of gastric fluid. Volume of gastric fluid aspirate was measured and pH of the same was noted using pH indicator paper strip (Merck pH).

For the purpose of this study, "risk" factors for aspiration pneumonitis were defined as (1) intragastric pH £ 2.5 and fluid volume > 0.4 mlkg-1 and (2) intra-gastric fluid volume ³ 1.0 mlkg-1. Gastric fluid volume ( GFV ) and pH were compared using ' t ' test. Anxiety, thirst and hunger were compared using the chi-square test.

   Results Top

Patient's characteristics are shown in [Table 1] and [Table 2] shows the results of mean GFV and pH of all the groups. In this study, we compared the results of mean GFV and pH of 4 hours and 8 hours fast with that of 2 hours, i.e. group I with group III and V; and group II with group IV and VI. We observed that group I had significant increase in pH and less GFV than group III and group V (P<0.05). Similar results were observed when group II was compared with group IV and group VI (P< 0.05)

[Table 3] shows one patient each in group III, IV and V had both GFV > 0.4mlkg -1 and pH £ 2.5 and one patient each in group I, II and VI whose GFV were >1.0 mlkg -1 falling under the "at risk category" for aspiration pneumonitis. Gastric aspirate could not be obtained from 2, 3 and 1 patients in group 1, II and III, respectively.

It is also apparent that as the duration of fasting increases, the number of patients having GFV>0.4 mlkg-1 increases, though it was not significant.

There was no significant difference in behavioral status in all the children [Table 4] but children in group I and II experienced less thirst and hunger [Table 5]

No patient regurgitated or aspirated.

   Discussion Top

The routine pre-operative order "Nil by mouth after midnight" applies to both liquids and solids ignoring both the difference in the rate of gastric emptying between solid foods and clear fluids, and the different scheduled time of surgery. It takes no account of the rapid gastric emptying of liquids which would pass through the stomach within 2 hours.

Reviews and studies [1],[2],[3],[4] indicate that there is no evidence that children who are not permitted oral fluids for more than six hours pre-operatively benefit in terms of intra-operative gastric volume and pH over children permitted unlimited fluids upto two hours pre-operatively. The children permitted fluids have a more comfortable pre-operative experience in terms of thirst and hunger.

Crawford M et al [6] found no correlation between the fasting interval, i.e., 2, 4 or 6 hours and either GFV or pH when water in a volume of 2 mlkg-1 was administered at the beginning of the fasting period in children aged 1-14 years. Splinter W.M. et al [7],[8] and Schreiner M.S et al [9] observed that drinking large volume of apple juice and clear liquids, respectively, up-to 2 hours before surgery does not have a measurable effect on GFV and pH and may offer benefits such as improved patient comfort.

The results in the present study are consistent with the previous studies substantiating that GFV and pH are independent of the duration of fast beyond 2 hours, provided that only clear liquids are consumed on the day of surgery. When more than 2 hours have elapsed following clear fluid ingestion, endogenous gastric secretion is the principal determinant of the pH and volume of gastric contents, i.e., salivary secretion (approximately 1 mlkg-1hr-1) and gastric secretion (approximately 0.6 mlkg-1hr-1). In absence of pathological factors, ingestion of most liquids increase the rate of gastric emptying. Clear fluids offer minimal resistance at the pylorus and, unlike milk products or solid foods, require no active antral contraction for the passage from stomach into small intestine. Another possible explanation is that the ingested clear fluid increased the pressure gradient between the stomach and duodenum, stimulating gastric peristalsis and, therefore, gastric emptying.

The rate of gastric emptying is inversely related to the osmolarity of ingested fluids. However, the effect of water (3 mOsm/L) on GFV and pH was similar to those reported for apple juice (650-700 mOsm/L). [8],[9] In this study GFV and pH, at the induction of anaesthesia, are not significantly affected by the ingestion of clear fluids, i.e., water or S.C.C.F., nor by premedication. [10],[11],[12] This may be explained, in part, by two factors; a) clear fluids with osmolarity in the range of 3-700 mOsm/L have no clinically detectable effect on GFV, Osmolarity of S.C.C.F used in this study was 538.48 mOsm/L and b) 2-hours fast allows sufficient time for the fluid in the stomach to empty.

It may be concluded that ingestion of clear fluids 2 hours before surgery in healthy children is unlikely to substantially affect the GFV and pH, while, at the same time, may provide some psychological benefits as evidenced by increased patient comfort and decreased thirst and hunger.

   Acknowledgement Top

We are highly indebted to Dr.(Mrs.) N.J. Arbatti, Assistant Professor of the Department of Bio-chemistry, Government Medical College, Surat, for her technical help.

   References Top

1.Cook-Sather SD, Harris KA, Chiavacci R, Gallagher PR, Schreiner MS. A liberalized fasting guideline for formula-fed infants does not increase average gastric fluid volume before elective surgery. Anesth Analg 2003; 96(4): 965-969.   Back to cited text no. 1      
2.Sethi AK, Chatterji C, Bhargava SK, Narang P, Tyagi A. Safe pre-operative fasting times after milk or clear fluid in children. A preliminary study using real-time ultrasound. Anaesthesia. 1999; 54(1): 51-59.   Back to cited text no. 2      
3.Ferrari LR, Rooney FM, Rockoff MA. Pre-operative fasting practices in pediatrics. Anesthesiology 1999; 90(4): 978-980.  Back to cited text no. 3      
4.CJ. Cote. Pre-operative preparation and pre-medication. Br J Anaesth 1999; 83 (1): 16-28.   Back to cited text no. 4      
5.Hawks A.M. Electrolytes and acid-base disturbances Varley's Practical Clinical Bio-chemistry, London : Heinmann Medical Books, 6th Edition. 1998: 560.   Back to cited text no. 5      
6.Crawford M, Lerman J, Christensen S and Farrow-Gillespie A. Effect of duration of fasting on gastric fluid pH and volume in healthy children. Anesth Analg 1990; 71: 400- 403.  Back to cited text no. 6      
7.Splinter WM, Stewart JA, Muir JG. The effect of preoperative apple juice on gastric contents, thirst and hunger in children. Can J Anaesth 1989; 36: 55-58.  Back to cited text no. 7  [PUBMED]    
8.Splinter WM, Stewart JA, Muir JG. Large volume of apple juice pre-operatively do not affect gastric pH and volume in children. Can J Anaesth 1990; 37: 36-39.   Back to cited text no. 8  [PUBMED]    
9.Schreiner MS, Triebwasser A, Keon TP. Ingestion of liquids compared with preoperative fasting in pediatric out patients. Anesthesiology 1990; 72: 593-597.   Back to cited text no. 9  [PUBMED]  [FULLTEXT]  
10.Maltby JR, Koehli N, Shaffer EA. Gastric fluid volume, pH and emptying in elective inpatients. Influences of narcotic atropine premedication, oral fluid and ranitidine. Can J Anaesth 1988; 35: 562-566.   Back to cited text no. 10  [PUBMED]    
11.Meakin G, Dingwall AE, Addison GM. Effects of fasting and oral premedication on the pH and volume of gastric aspiration in children. Br J Anaesth 1987; 59: 678-682.   Back to cited text no. 11  [PUBMED]  [FULLTEXT]  
12.Salem MR, Wong AY, Mani M, Bennett EJ, Toyama T. Premedicant drugs and gastric juice pH and volume in pediatric patients. Anesthesiology 1976; 44: 216-219.  Back to cited text no. 12  [PUBMED]  [FULLTEXT]  


  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]


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