Comparison of Gastric Volume After 6-hour and 8-hour Fasting in Patient Scheduled for Elective Surgery
Conditions: Gastric Volume, Ultrasonography
Sponsor: Indonesia University

Date: June 13th 2019 
 
Comparison of Gastric Volume After 6-hour and 8-hour Fasting in 
Patient Scheduled for Elective Surgery 
  
Meliani Anggreni, Jefferson Hidayat, Raden Besthadi Sukmono  
Department of Anesthesiology and Intensive Therapy 
Faculty of Medicine, University of Indonesia- RSUPN Dr. Cipto Mangunkusumo 
Jalan Diponegoro No. 71, Jakarta, 10430, Indonesia 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Date: June 13th 2019 
 
Background 
The incidence of perioperative aspiration associates with significant morbidity and 
mortality for patients who will undergo surgery, especially in the length of 
hospitalizations and use of mechanical ventilation.1 Perioperative aspiration is an 
undesirable risk although the incidence is rare. The incidence of aspiration ranges from 
<0.1% to 19% depends on patient factors and factors of surgery performed.2 Sedation 
and anesthesia reduce or even eliminates physiological reflexes that protect the risk of 
aspiration, such as lower esophageal sphincter muscle tone and upper airway reflex.3 
 
One of the risk factors of aspiration is the amount and type of gastric content so that 
elective surgery patients will fast before the operation. ASA guideline recommends 8 
hours of fasting after eating for patients who will undergo elective surgery.4 8-hours 
fasting after consumption of fatty foods or fried foods are considered adequate by ASA 
guideline for the elective surgical patient. 4 However, special conditions such as 
diabetes patients, critical patients, digestive disease, and other diseases cause variations 
in the duration of gastric emptying.2,4 The longer patients do the fasting increase the 
risk of dehydration, hypoglycemia, and other problems, especially in patients with 
metabolic disorders. RSCM recommends 6-hours of fasting before undergoing elective 
surgery to reduce the period of prolonged fasting. Moreover, the types of food 
consumed in Indonesia have a lower fat content compared to ASA guidelines. 
 
Ultrasound examination is an invasive examination and easy to administer performed 
which can show the volume of the hull in real-time to predict aspiration risk. Gastric 
volume resulting in an increased risk of aspiration remains controversial, but healthy 
patients who do fasting often have a residual gastric volume of about 1.5 ml/kg without 
an increased risk of aspiration.2,4 
 
Until now, several studies have stated that ultrasound examination can predict gastric 
volume. This examination is useful for assessing the patient who in an emergency 
condition with an unclear fasting condition that requires medical treatment soon. A 
study assessing gastric contents in fasting patients using ultrasound has not been done 
in Indonesia. Ultrasound of gastric contents has become an option in many countries 
such as Sweden, and Canada to assess the risk of perioperative aspiration. 
 

Date: June 13th 2019 
 
Research Problems 
Prolonged fasting can negatively affect the patient, especially the patient with a high 
risk of anesthesia. Currently, in RSCM, 6 hours of fasting is considered sufficient as 
preparation for elective surgery. There are differences from the ASA guidelines that 
state recommendations for 6-hours fasting after snacks and 8-hours fasting after solid 
foods. This research aims to analyze the difference in gastric volume after 6-hours of 
fasting compared with 8-hour fasting in patients undergoing elective surgery. 
 
Research purposes 
This study aims to compare gastric volume in fasting patients as preparation for elective 
surgery. Prolonged fasting has a negative impact on the patient's condition, especially 
patients with risk factors such as sepsis, diabetes, and various other conditions. If there 
is no significant difference in gastric volume after 8 hours of fasting compared to gastric 
volume after 6 h of fasting, then a 6-hour fasting period may be considered to reduce 
the risk of aspiration in the patient who will undergo elective surgery. 
 
 
Research Methods 
Research design 
This is a cohort study of patients undergoing non-digestive elective surgery. This 
research was conducted in the hospital ward RSUPN dr. Cipto Mangunkusumo from 
January to February 2019. The estimated number of samples with an estimated drop 
out of 10% are 35 subjects. Sampling is done after obtaining approval from the Ethics 
Committee of the Faculty of Medicine, University of Indonesia. 
 
Inclusion and Exclusion Criteria 
The inclusion criteria were patients aged 18-60 years, ASA 1-2 who would undergo 
non-digestive elective surgery in RSCM with a body mass index between 20-30 
kg/m2. Exclusion criteria were a patient who is not willing to enter the study, patients 
with diabetes mellitus, pregnancy, abdominal distension, intestinal motility disorders, 
history of dyspepsia, or patients who do not receive the standard RSCM diet and 
changes of the surgery schedule in which the patient is unable to do 8-hours fasting 
before surgery, the patient who has an emergency in the perioperative period and the 
patient was unable to consume the standard food provided. 

Date: June 13th 2019 
 
 
Sampling technique 
Samples were obtained consecutively. Subjects were recruited based on an elective 
operating schedule recorded at the RSCM one day before the procedure. Subjects who 
met the inclusion criteria and did not have exclusion criteria will be explained regarding 
the research procedure in the ward by researchers. A sign of consent to be included in 
the research will be written on the informed consent sheet if the subject is willing to 
take part in the research. If the subject cannot sign the informed consent sheet, the 
signature can be represented to the patient's main family. 
 
Data collection techniques and variables to be measured 
After the subjects agree to take part in the research, an initial examination will be carried 
out for obtaining subject demographic data, including age, weight and height, type 
surgery to be performed, and preoperative examinations. The subject will start 8 hours 
of fasting before the surgical planning time. Before fasting, the subjects were given 
standard food RSCM with standardized nutritional levels. Subjects were given 1 hour 
to consume the standard RSCM food. 6 hours after the standard meal is consumed, an 
ultrasound examination will be performed with the right lateral decubitus position to 
obtain ultrasound imaging of the antrum after 6 hours of fasting. After that, the subject 
continues fasting for up to 8 hours after consumption of solid food. Furthermore, an 
Ultrasound examination is performed using the same technique to obtain images of 
ultrasound imaging of the antrum after 8 hours of fasting. Imaging pictures are taken at 
the time relaxation of the antrum, between two contractions. The results of this imaging 
are stored and assessments of antrum craniocaudal (CC) and anteroposterior (AP) 
diameters were performed by research assistants who don't know when the image was 
taken. The volume of the stomach was calculated with the formula 𝐺𝑉= 27.0 +
14.6 × 𝐶𝑆𝐴−1.28 × 𝑎𝑔𝑒. 
 
Statistical analysis 
The data collected is processed using the Statistical Package for Social Scientist 
program (SPSS) version 23.0. Numerical data with normal distribution will be analyzed 
using the T-test 
in pairs. If the data has an abnormal distribution, the data will be analyzed using the 
Wilcoxon test. The data obtained is the result of repeated examinations, so that the 

Date: June 13th 2019 
 
analysis will be adjusted using the Bonferonni correction factor. Categorical data will 
be analyzed using the McNemar test. The results of data processing are displayed in 
tabular form. The CSA can be calculated with the formula 𝐶𝑆𝐴=
𝜋×𝐶𝐶×𝐴𝑃
4
. The gaster 
volume was grouped into sufficient and insufficient with a border value of 1.5ml/kg.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Date: June 13th 2019 
 
Participant initials : 
 
Comparison of Gastric Volume After 6-hour and 8-hour 
Fasting in Patient Scheduled for Elective Surgery 
 
 
This research information sheet explains the purpose, procedure, and usefulness of the 
research, so that you understand what research is going to be about and can decide 
whether to participate or not. This sheet also contains patient rights and our 
responsibility as researchers in conducting this research. 
  
Research purposes 
Aspiration is a rare, but fatal, risk of anesthesia. Currently, there are various efforts to 
reduce these risks, such as fasting. Prolonged fasting can have a negative impact on 
patients, especially in patients at high risk of anesthesia. This study aimed to compare 
the gastric volume after 6 hours of fasting versus 8 hours of fasting in patients 
undergoing elective surgery.  
 
Research procedure 
If you have decided to participate in this research, then you can sign a consent form 
stating that you have been given an explanation of this research and voluntarily agree 
to participate. Your stomach will be examined using ultrasound to determine the 
volume of the stomach. This examination will be carried out four times, namely before 
you eat the food that is given, after eating the dinner that has been provided, after fasting 
for 6 hours, and after fasting for 8 hours. 
  
Possible benefits and Confidentiality 
This examination is useful for knowing the volume of the stomach, where it will be a 
measure of whether your fasting is enough before surgery. Sufficient fasting is useful 
for reducing the incidence of aspiration associated with anesthesia. The confidentiality 
of the results of this examination will be guaranteed and used for research following 
the permission of the Ethics Committee of the Faculty of Medicine, University of 
Indonesia. 
 
Contact 
This research was conducted by dr. Jefferson, Sp.An-KAKV in the Department of 
Anesthesiology and Intensive Therapy FKUI / RSCM.  
 
 
Thank you. 
 
 
 
 
dr. Jefferson, Sp.An-KAKV 

Date: June 13th 2019 
 
RESEARCH PARTICIPATION AGREEMENT 
(INFORMED CONSENT) 
 
I the undersigned hands at the bottom of this: 
Name  
 
: 
Age 
 
 
: 
Gender 
 
: 
Address 
 
: 
 
With full awareness and without coercion, has been given an adequate and stated 
explanation 
AGREE / DO NOT AGREE 
To participate as a research subject entitled: 
"Comparison of Gastric Volume After 6-hour and 8-hour Fasting in Patient 
Scheduled for Elective Surgery" 
which is (self / husband / wife / parent / child *) 
Name  
 
: 
Age 
 
 
: 
Gender 
 
: 
Address 
 
: 
Medical Record No 
: 
I understand the purpose of this research and the reasons why I was asked to participate. 
I declare that my participation in this research is voluntary and without coercion from 
any party. 
 
Jakarta, ___________________2019 
 
 
 
 
 
  ___________________                                              ___________________                                             
Investigator 
 
 
 
 
 
Patients, parents or guardian 
 
 

Date: June 13th 2019 
 
 
RSUPN Dr. Cipto Mangunkusumo 
Jl. Diponegoro No. 71 Jakarta 10430 
Tel: (021) 3918301  Fax : (021) 3148991 
 
RESEARCH PARTICIPATION AGREEMENT 
(INFORMED CONSENT) 
Principal Investigator 
: dr. Jefferson, Sp.An-KAKV 
Informant 
: dr. Meliani Anggreni 
Recipient of Information 
Name 
Date of Birth / Age 
Gender 
Address 
Contact 
 
: 
: 
: 
: 
: 
No 
Type of Information 
Content 
Check 
1 
Title of research 
Comparison of Gastric Volume After 6-
hour and 8-hour Fasting in Patient 
Scheduled for Elective Surgery 
 
2 
Research purposes 
This study aimed to evaluate gastric 
contents after 6 hours of fasting versus 8 
hours of fasting as a preparation for 
patients undergoing elective surgery. 
 
 
 
Med Rec No 
: 
Name   
: 
Age    
  
: 
Date of Birth  
: 

 
 
 
3 
Research procedure 
If you are aged 18-65 years who are going 
to undergo surgery that is not related to the 
digestive organs and meet the selection 
criteria, then you are expected to 
participate in this study. 
In this study, you will be examined the 
contents of the stomach using an 
ultrasound machine. The examination will 
be carried out four times, namely before 
consuming the RSCM standard food, after 
finishing the food provided, after 6 hours 
of fasting, and 8 hours of fasting. The 
duration of fasting will be adjusted to the 
scheduled operating hours. 
All research data will be kept confidential 
so that it is not possible to be misused by 
others. In addition, your participation in 
research is voluntary (no coercion). You 
have the right to refuse to participate or 
not.  
 
4 
Number of subjects 
35 subjects 
 
5 
Research time 
January – June 2019 
 
6 
The benefit of the 
research 
This study aimed to evaluate gastric 
volume after 6 hours and 8 hours of 
fasting. You will also find out whether 
your fast is long enough to prepare for pre-
surgery. 
 
7 
Risks and side 
effects in research 
Nothing 
 

 
 
 
8 
Subject’s discomfort 
At the time of the gastric ultrasound 
examination, you will feel a little 
discomfort. 
 
9 
Compensation for 
side effects 
There is no compensation. You will be 
treated following applicable hospital 
procedures. 
 
10 
Alternative treatment 
(if any) 
Nothing 
 
11 
Data confidentiality 
All research data will be kept 
confidential. 
 
12 
The name and 
address of the 
researcher that can 
be contacted 
dr. Jefferson, Sp.An-KAKV 
Department of Anaesthesiology and 
Intensive Therapy 
 
 
After listening to the explanation regarding the research that will be conducted by dr. Jefferson, 
Sp.An-KACV with the title: " Comparison of Gastric Volume After 6-hour and 8-hour Fasting in 
Patient Scheduled for Elective Surgery" I understand this information well. 
By signing this form, I agree to be included in the research voluntarily without coercion from any 
party. If at any time I feel harmed in any form, I have the right to cancel this agreement. 
 
 
______________________________ 
 
 
_________________ 
Signature 
 
 
 
 
 
 
Date 
______________________________ 
Subject’s name 
 
 
______________________________ 
 
 
_________________ 
Signature of the Guardian 
 
 
 
 
Date 
______________________________ 
 
 

 
 
 
Name of the guardian: 
 
I have explained to the patient truthfully and honestly the purpose of the study, the benefits of 
the study, the research procedures, as well as the potential risks and inconveniences that may 
arise (detailed explanations correspond to the items I marked above). I have also best answered 
research-related questions. 
 
 
_____________________________  
 
 
__________________ 
Investigator Signature  
 
 
 
 
Date