Running head: PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
Does Preoperative Carbohydrate Loading Have Adverse Effects for Elective Surgery Patients
Compared to Overnight Fasting
Andrea Dooley, Alex Harmening, Kelli Richardson, Ally Riddle, Ciera Thomson, & Julie
Trumbull
Auburn University
1
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
2
PICO Question and Significance
Based on the most recent statistics from the National Center for Health Statistics of the
U.S. Center for Disease Control, over 40 million elective procedures are performed in the United
States annually. Because elective surgeries are planned and not emergent, special precautions
are taken preoperatively to reduce the risk of surgical complications. Currently, preoperative
fasting is the customary practice used to prevent perioperative pulmonary aspiration in adults
(Oyama et al., 2011). The American Society of Anesthesiologists Committee on Standards and
Practice Parameters (ASA, 2011) states that clear liquids be withheld two hours prior to
procedure, light meals be withheld six hours prior to procedure, and fried, fatty foods and meat
be withheld eight hours prior to procedure to ensure gastric emptying.
However, as new practices emerge, evidence-based practice nurses must reevaluate the
benefits and risks of current preoperative fasting standards. While preoperative fasting has been
proven effective in the prevention of pulmonary aspiration, patients often report discomfort and
hunger. According to Helminen, Viitanen, and Sajanti (2009), patients who were fasting became
hungry, thirsty, tired, weak, and anxious before surgery. Although current guidelines only
require a six to eight hour fasting time, this period may be prolonged due to unexpected delays in
initiation of surgery increasing patient discomfort (Yagci et al., 2008). Preoperative fasting has
also been linked to the development of insulin resistance. Bilku, Dennison, Hall, Metcalfe, and
Garcea (2014) define insulin resistance as a central metabolic change caused by stress on the
body that leads to hyperglycemia in non-diabetic patients. This complication leads to prolonged
recovery and length of stay, and consequently increases overall cost of the procedure (Helminen
et al., 2009).
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
3
From this evaluation, the evidence-based practice nurse must ask oneself if preoperative
fasting is truly the best practice for patients undergoing elective surgery. If the answer is no, then
the nurse must determine which technique will be more beneficial. One alternative technique to
preoperative fasting is preoperative carbohydrate loading. Researchers explain that the aim of
preoperative carbohydrate loading is to trigger the insulin response in order to reduce insulin
sensitivity during the perioperative period (Helminen et al., 2011). Another study also suggests
that preoperative carbohydrate loading reduced postoperative nausea and vomiting and
antiemetic consumption during the preoperative period, while posing no threat of pulmonary
aspiration (Yilmaz, et al., 2013). Because this is a relatively new technique in regard to
preparation for elective surgeries, current guidelines governing the practice could not be found.
However, most studies provided a carbohydrate beverage two hours prior to procedure.
This gives rise to the question of whether preoperative carbohydrate loading (I) is more
effective in lessening adverse effects (O) in patients undergoing elective surgery (P) than the
routine six to eight hour preoperative fasting guidelines (C). Because nursing care should be
patient-centered, a major significance of this evidence-based practice, or PICO, question is to
determine which practice optimizes patient comfort and satisfaction. Because many surgical
complications lead to a need for increased resources and extended length of stay, it is essential to
determine which practice is most effective in the prevention of these problems in order to
provide efficient and cost-effective nursing care.
Review of Evidence
The research for this project was conducted using the Auburn University online
library databases.
The databases searched were PubMed, CINAHL, Cochrane, and
MEDLINE (EBSCO). Key words searched were “preoperative”, “carbohydrate loading”,
4
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
“carbohydrate therapy”, “fasting”,
“glucose”, and “adverse effects”.
The search was
narrowed through filtering articles published within the past ten years. Through these
research guidelines, we found three experimental studies, two randomized control trials,
and two systematic review articles that were used to conduct our research. Further, one of
the randomized control trials is a double blind trial, one of the experimental studies is a
cross over randomized order, one of the systematic reviews reviewed randomized clinical
trials, and the other systematic review was a meta-analysis systematic review. Finally,
clinical guidelines for “preoperative fasting” were found from The National Clearing House
Guidelines, but no specific guidelines for “carbohydrate loading” were accessed.
5
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
Evidence Grid: Effects of Preoperative Oral Carbohydrates and Trace Elements on Perioperative Nutritional Status in Elective
Surgery Patients
Authors of
Purpose of
Research elements:
Major findings/
Give strengths and
article/Yr
study/research
*Design *Population
findings relevant to your
weaknesses of this
questions
*sampling method
project
article for your
Level of
*sample size *description of
project related to
evidence
methods/interventions (if any)
validity, bias and
*instruments used
applicability
*outcomes measured
Yoshimasa
Oyama
Hideo Iwasaka
Keisuke Shihara
Satoshi
Hagiwara
Nobuhiro Kubo
Yutaka Fujitomi
Takayuki
Noguchi
(2011)
Level of
Evidence: Level
III
Kelli Richardson
The aim of this
study was to
evaluate the
effects of an
18%
carbohydrate
(CHO) drink
containing trace
elements on
preoperative
nutritional state
and trace
element levels as
compared with
conventional
fasting protocol.
Design: This is a posttest only
experimental design.
Population: The elective surgery
patients, between the ages of 20 and
89, a BMI between 18 and 35, and
American Society of Anesthesiologist
(ASA) physical status classification
1-3. Excluded patients were those
with diabetes, abnormal glucose
tolerance, upper gastrointestinal
disease, ileus, use of drugs that
delayed gastric emptying, and those
needing to begin fasting two days
preoperatively.
Sampling method: Patients were
chosen against selection and
exclusion criteria, listed above. This
was a nonprobability convenience
sample because it only consists of
patients from the one hospital where
the study was conducted. No further
information was given about the
sampling method.
Preoperative consumption of
a drink containing CHO has
been reported to suppress
surgical stress-induced
catabolism, thereby
attenuating insulin resistance.
This treatment also enhanced
postoperative recovery and
shortened hospitals stays.
This study showed that
preoperative drink
supplementation can mitigate
the stress experienced by
patients before surgery, thus
improving their perioperative
experience. Higher serum Zn
concentrations were observed
in the CHO groups,
suggesting that ingesting a
CHO drink with trace
elements may maintain ZN
storage in bone, muscle, and
the liver, aiding in wound
By grouping subjects
according to morning
or afternoon surgery,
seasonal fluctuations
in metabolism may
have influenced the
results. In addition, the
post-operative
observation period
was short, so the longterm effects of CHO
consumption, such as
days hospitalized or
would healing, were
not assessed. Longterm studies at
multiple
hospitals/institutions
will be needed to
confirm these
findings.
6
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
Sample Size: The sample size was
122 patients having elective surgery.
Description of
methods/interventions: The 122
patients were divided into 2 groups,
one receiving the CHO drink and one
using conventional fasting protocol,
and then further divided into AM/PM
surgery times. The patients receiving
the CHO drink 2-3 hours before
surgery. Blood glucose, nonesterified
fatty acid, RBP, Zn, Cu, BUN, and
Creatinine were collected
immediately after anesthesia
induction and again the following
morning. A questionnaire was used to
assess patient discomfort before
surgery, asking about thirst, hunger,
and anxiety.
Instruments used: Patients were
placed into a category by nominal
measures: AM/PM surgery, and
CHO/fasting. A Likert scale was used
to receive responses about
preoperative discomfort in a
questionnaire. Intervals were used to
record preoperative and postoperative
trace element levels and nutritional
status.
Outcomes: Compared to the
conventional preoperative fasting ,
preoperative consumption of a CHO
drink containing trace elements
healing postoperatively. This
study showed that there were
no adverse affects to ingesting
the CHO drink preoperatively,
so it could be used on all
patients to give additional
benefits.
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
suppressed preoperative metabolic
fluctuations without causing adverse
effects, and trace element deficiency
was circumvented.
7
8
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
Evidence Grid: Randomized control trial of preoperative oral carb treatment in major abdominal surgery
Authors of
Purpose of
Research elements:
Major findings/
article/Yr
study/research
*Design *Population
findings relevant to your
questions
*sampling method
project
Level of evidence
*sample size *description
of methods/interventions (if
any) *instruments used
*outcomes measured
S. Mathur, L. D.
The purpose of
Design-Double-blind
The median duration of
Plank, J. L.
this study was to
randomized controlled trial
hospital stay for carbohydrate
McCall, P.
investigate the
Population- Patients having
loading patients was 7 days
Shapkov, K.
effects of
elective major abdominal
and the median for the
McIlroy, L. K.
preoperative
surgery
placebo group was 8 days.
Gillanders, A. E.
carbohydrate
Sampling method- Patients There was not a large
H. Merrie, J. J.
loading on clinical undergoing major elective
difference in postoperative
Torrie, F. Pugh, J. outcome after
surgery or hepatic resection
fatigue, biochemistry, grip
B. Koea, I. P.
major abdominal
at Auckland City Hospital or strength and mid-arm muscle
Bissett and B. R.
surgery.
Mercy Hospital, Auckland
conference or total body
Parry (2010)
Sample Size- 162 were
protein in the two groups.
randomly assigned, however Overall preoperative
Level of
76 in the carbohydrate group carbohydrate loading
Evidence: II
and 79 in the placebo group
treatment did not improve
were used in the experiment fatigue and duration of
hospital stay. While it did not
Instruments usedCarbohydrate loading and
improve these it also did not
placebo substance the night
have a negative effect on
before the surgery and 2
them either.
Julie Trumbull
hours before anesthesia was
given
Outcomes measuredeffects of carbohydrate
loading on fatigued and
discomfort, duration of
Give strengths and
weaknesses of this article
for your project related to
validity, bias and
applicability
Strengths and validity:
1) Large sample size (162)
2) True randomized control
trial
3) Double blind trial
Weaknesses:
1) Samples were only taken
from 2 hospitals
2) The procedures in the
surgeries varied
Significance for this project:
Preoperative carbohydrate
loading has neither positive
nor negative effects
postoperatively.
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
hospital stay, biochemistry,
grip strength and mid-arm
muscle conference, and total
body protein. The primary
ones measured were fatigued
and duration of hospital
stays.
9
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
Evidence Grid: Effect of preoperative intravenous carbohydrate loading on preoperative discomfort in elective surgery patients
Authors of
Purpose of
Research elements:
Major findings/
Give strengths and
article/Yr
study/research
*Design *Population
findings relevant to your
weaknesses of this article
questions
*sampling method
project
for your project related to
Level of evidence
*sample size
validity, bias and
*description of
applicability
methods/interventions (if
any) *instruments used
*outcomes measured
Heli Helminen,
The purpose of this
This was a prospective,
During the wait before
This study examined several
Hanna Viitanen
study was to compare randomized study that
surgery, the carbohydrate-rich weaknesses that should be
and Juha Sajanti
three different types
included 210 patients
drink group reported
taken into account. For
of preoperative
from Seina ̈joki Central
decreasing thirst but
example, certain variables
2009
fasting protocols:
Hospital. Inclusion
increasing hunger and mouth such as pre-operative
overnight intravenous criteria were adults
dryness (P < 0.05). However, anxiety can be complex and
Level of
5% glucose infusion
undergoing elective
the CHD group was less
can vary significantly
Evidence: Level
(1000 ml),
surgery and who were Ihungry than the fasting group according to certain patient
II
carbohydrate-rich
III according to ASA.
(P = 0.011). The intravenous characteristics and
drink (400ml) and
Patients were randomly
glucose group also showed
backgrounds. The study
overnight fasting.
assigned to one of the
increasing thirst, mouth
also failed to fully evaluate
Ciera Thomson
The subjective
three treatment groups.
dryness, and anxiety (P <
the safety of preoperative
feelings of thirst,
Patients with overnight
0.05). In the fasting group,
drinking before anesthesia
hunger, mouth
glucose infusion were
thirst, hunger, mouth dryness, and cannot deem it safe for
dryness, weakness,
given 1000 ml of IV 5%
weakness, tiredness and
all persons with various
tiredness, anxiety,
glucose solution (1⁄4200
anxiety increased (P < 0.05).
diseases. Furthermore, the
headache and pain of kcal) between midnight
Both glucose and insulin
study only took place at one
each patient were
and 6 a.m. Patients in the
levels were significantly
hospital. Overall, this study
questioned and
carbohydrate-rich drink
increased with the CHD group was very applicable to our
recorded. Serum
(CHD) group were given
and intravenous glucose
research topic because it
glucose and insulin
nothing after midnight and group.
evaluated not only carblevels were measured a 12.5% CHD that is
Overall the intravenous
loading verses fasting, but
preoperatively as
400ml (1⁄4200 kcal),
glucose infusion does not
compared a carbohydratewell.
between 6 and 7 a.m.
decrease the sense of thirst
rich drink with intravenous
10
11
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
Patients in the fasting
group were given nothing
by mouth after midnight.
The patients were asked to
score their subjective
sense of discomfort with a
visual analogue scale
during the study. Thirst,
hunger, dryness of mouth,
weakness, tired- ness,
anxiety, headache and
pain were the variables
tested. They were
recorded in the evening
(10 p.m.) before operation
and in the morning (6
a.m.).
and hunger as effectively as a
carbohydrate-rich drink but
does alleviate the feelings of
weakness and tiredness
compared with fasting.
glucose and how those two
results compared to
preoperative fasting.
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
Evidence Grid: Effects of preoperative carbohydrate loading on glucose metabolism and gastric contents in patients undergoing
moderate surgery: a randomized, control trial
Authors of
Purpose of
Research elements:
Major findings/
Give strengths and
article/Yr
study/research
*Design *Population
findings relevant to your
weaknesses of this article
questions
*sampling method
project
for your project related to
Level of evidence
*sample size *description
validity, bias and
of methods/interventions (if
applicability
any) *instruments used
*outcomes measured
Gokhan Yagci,
The purpose of
This article is a randomized
There were no adverse effects The article addresses several
M.D., Mehmet
this study was to
control trial. The population reported by the treatment
limitations in the study.
Fatih Can, M.D., evaluate the safety consisted of patients in the
group. The plasma glucose
They did not attempt to
Erkan Ozturk,
and effects
hospital undergoing surgery
levels were significantly
determine if the
M.D., Birgul Dag, preoperative
that was classified according higher in the treatment group carbohydrate loading was an
M.Sc., Taner
carbohydrate
to the American Society of
(initial 86.06 -10.9 mg/dL,
advantage in overall patient
Ozgurtas, M.D.,
loading has on
Anesthesiologists (ASA) as a final 83.03 - 8.2 mg/dL) than outcome. This could be
Ahmet Cosar,
patients
score of I or II. Patients with in the control group (initial
considered a weakness for
M.D., and Turgut undergoing
diabetes mellitus or a history 74.12 - 24.1 mg/dL, final
our project however they
Tufan, M.D.
standardized
of any gastric or endocrine
70.85 - 22.3 mg/dL). Serum
thoroughly evaluated the
moderate surgery. disorder that might influence insulin levels were elevated
effect the treatment had on
2008
This study also
the metabolic measurements initially in the test group but
glucose and insulin levels.
sought to establish were excluded. Seventy
returned to control levels by
The study also failed to
Level of
current guidelines patients from a hospital in
the time of anesthesia
thoroughly test each patient
Evidence: Level
for the
Turkey were included in this induction. The two groups
for possible gastric
II
preoperative care
study. They were randomly did not have a significant
emptying problems, which
of patients.
assigned into two different
difference in gastric residue
could have interfered with
groups. The treatment
contents or gastric pH,
results. Glucose and insulin
Ciera Thomson
group, thirty-four patients,
suggesting the procedure to be levels were recorded by
received a carbohydrate-rich safe in terms of aspiration
investigators who were
beverage on the evening
risk.
blinded to the study group
before surgery and 2 hours
in order to prevent biases.
before the induction of
anesthesia. Thirty-six
12
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
patients in the control group
underwent surgery after
overnight fasting. The
preoperative residual gastric
contents were measured and
during the perioperative
period and anesthesia
induction, plasma glucose
and serum insulin levels
were obtained.
13
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
Evidence Grid: Effect of preoperative carbohydrate loading on the management of blood glucose and body temperature
Authors of
Purpose of
Research elements:
Major findings/
Give strengths and
article/Yr
study/research
*Design *Population
findings relevant to your
weaknesses of this article
questions
*sampling method
project
for your project related to
Level of evidence
*sample size *description
validity, bias and
of methods/interventions (if
applicability
any) *instruments used
*outcomes measured
Design: crossoverYatabe T.,
The purpose of
randomized order
1. It was found that
Weaknesses:
Tamura T., and
this experiment
Population: 6 healthy
aggravation of postoperative
1.) The studies only
Yokayama M.
was to investigate volunteers
insulin resistance could be
included 6 patients which
(2013). Effect of
the effects of
Experiment 1 Methods:
alleviated with adequate
decreases the validity of the
preoperative
preoperative
Carbohydrate beverages
control of intraoperative
experiment
carbohydrate
carbohydrate
were given both in the
blood glucose levels. If
2.) The study on
loading on the
loading on the
evening and morning, and no intraoperative blood glucose
hypoglycemia was
management of
patient’s blood
administration. The amounts levels can be controlled then
conducted on rats and rats
blood glucose and glucose.
of administered carbohydrate postoperative glucose control metabolism is five to
body temperature.
beverage in the evening on
becomes easier leading to less sevenfold that in humans, so
JA Symposium.
the day before the test and in infection and decreased
it is necessary to clinically
28, 148-151.
the morning of the day of the hospital stay.
examine the extent of the
DOI: 10.
test were defined as 800 ml
2. Preoperative carbohydrate
effect on humans
1007/s00540-013and 400 ml.
loading is a low cost, simple,
1470-3
Results: the intake of
and easy approach for the
Strengths:
carbohydrate beverage in the improvement of insulin
1) The experiment used
Level of
morning of the test day
resistance and prevention of
different percentages of
evidence: Level II
might alleviate aggravation
perioperative hypothermia,
carbohydrate beverages
of insulin resistance as
which may lead to improved
allowing us compare the
Andrea Dooley
significantly as 3.2
prognosis in perioperative
results to a patient who is
mg/kg/min
patients
NPO.
Experiment 2 methods: 6
3. Glucose infusion rate was
healthy volunteers were
higher in group A indicating
separated into 2 groups:
that insulin resistance
14
15
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
group A and group B. Group
A was given 375 ml of an
18% carbohydrate beverage
(67.5 g carbohydrate) and
250 ml of an 18%
carbohydrate beverage (45 g
carbohydrate) were
administered at 21:00-24:00
before the test day and at
6:30 on the morning of test
day. In group B, the subjects
consumed only water and tea
after 21:00 on the day before
the test.
Experiment 2 Results:
Glucose infusion rate was
significantly higher in group
A than group B which
indicated that insulin
resistance improved with the
18% carbohydrate beverage
compared to fasting
improved with the 18%
carbohydrate beverage
4. Carbohydrate loading with
a 12.6% carbohydrate
beverage the morning of the
test day can alleviate
aggravation of insulin
resistance
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
Evidence Grid: Preoperative carb loading: a review of the current evidence
Authors of
Purpose of
Research elements:
Major findings/
article/Yr
study/research
*Design *Population
findings relevant to your
questions
*sampling method
project
Level of
*sample size *description
evidence
of methods/interventions
(if any) *instruments used
*outcomes measured
Shanley S.
The purpose of
Design: systemic manner of 1. Reduced insulin sensitivity
(2009).
this study was to
randomized clinical trials
has been associated with
Preoperative
review the current Sampling method: 16
increased surgical outcome
carbohydrate
evidence relating
randomized control trials. 13 and enhanced patient
loading: a review to preoperative
randomized trials all
recovery
of current
carbohydrate
measured clinical outcomes 2. Preoperative carbohydrate
evidence. Journal loading,
after a preoperative
loading could reduce post
of Human
particularly
carbohydrate load 2-3 hours operative insulin resistance
Nutrition ad
focusing on
prior to elective surgery. The 3. No adverse effects were
Dietetics. 22,
outcomes
other 3 groups were
seen with pre operative carb
256-275.
including
excluded. Nine of the 13
loading
postoperative
studies had a placebo group
Level of
complications,
and six studies had a control
evidence: Level I patient wellbeing
group
and length of
Sample size: the number of
Andrea Dooley
hospital stay.
patients included in each
study varied greatly, from
12-252
Results: a preoperative
carbohydrate load could
reduce post- operative
insulin resistance
- None of the trials noted
any adverse affects as a
result of preoperative
carbohydrate load therefore
16
Give strengths and
weaknesses of this article
for your project related to
validity, bias and
applicability
Strengths:
1) The body of evidence
surrounding reduced insulin
resistance was of good
quality and was consistent
with other studies
2) The post operative regimen
was similar in all 13 studies
and was standardized in study
groups
Weakness:
1) Individual studies did not
provide significant evidence
with regard to reduced length
of stay, reduced loss of lean
muscle mass and patient well
being, so more research on
these topics will need to be
done
2) Seven studies had unequal
sample sizes between
comparison groups
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
indicating that overnight
fasting guidelines in elective
surgery should be
questioned
17
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
Evidence Grid: Preoperative carbohydrate nutrition reduces postoperative nausea and vomiting compared to preoperative fasting
Authors of
Purpose of
Research elements:
Major findings/
Give strengths and
article/Yr
study/research
*Design *Population
findings relevant to your
weaknesses of this article
questions
*sampling method
project
for your project related to
Level of evidence
*sample size *description
validity, bias and
of methods/interventions (if
applicability
any) *instruments used
*outcomes measured
Yilmaz, N. ,
The purpose of
Design: The study has an
There were no significant
Strengths: 1.) The patients,
Cekmen, N.,
this study was to
experimental design.
differences in gastric pH and
researchers, and staff were
Bilgin, F., Erten,
compare the
Population: The population residual volume between
blind to the fasting and
E., Ozhan, M. O., effects of
is patients undergoing
patients in group F and
carbohydrate drink, which
& Cosar, A.
preoperative CHO elective laparoscopic
patients in group C.
decreases bias in
(2013)
loading (400ml
cholecystectomy.
However, less preoperative
measurement and
drink given 2 h
Sampling: Patients were
anxiety was reported by
interpretation of results.
prior to surgery)
randomly assigned to two
patients in group C. There
Weaknesses: 1.) This study
and preoperative
groups according to a
was no significant difference
was only conducted on
LOE: Level II
fasting (8 h prior
computer generated
in VDS scores and antiemetic patients undergoing elective
(RCT)
to surgery) on
randomization list: group F
consumption during the
laparoscopic
postoperative
(fasting) or group C
PACU period, but overall
cholecystectomy. While the
gastric pH and
(carbohydrate drink). The
VDS scores and antiemetic
study gave good evidence
Ally Riddle
residual volume,
sample size for this study
consumption was much lower regarding preoperative
nausea and
was 40 patients. Group F
in group C than group F 24 h carbohydrate loading and
vomiting, and
and group C consisted of 20
after the procedure. Group C this procedure, it may not be
antiemetic
patients each. Patients,
reported greater patient
applicable to other
consumption in
researchers, and nursing staff satisfaction and less anxiety
procedures. 2.) This study
patients
were all blinded to the
than group F. The fact that no only consisted for 40
undergoing
fasting and carbohydrate
complications arose during
participants. The validity of
laparoscopic
drink.
surgery supports that oral
the study would be
cholecystectomy.
Interventions: Patients in
intake of 400mL carbohydrate increased if the sample size
group F were placed NPO
drink 2 h prior to elective
were larger.
for 8 h prior to surgery.
surgery did not increase the
Patients in group C were
risk of aspiration.
18
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
given 400 mL of an oral
carbohydrate solution
containing 12.5% glucose 2
h prior to surgery. All other
preoperative procedures were
consistent for both groups.
Instruments: A 16-Fr
nasogastric tube was placed
to obtain gastric residue. A
urine pH meter was used to
measure gastric pH. Verbal
Descriptive Scale (VDS) and
State-Trait Inventory were
used to measure nausea and
anxiety. VDS was also used
to measure the severity of the
nausea. Postoperative
nausea and vomiting scores
were measured while
patients were in PACU and
24 h after the procedure.
Antiemetic consumption was
documented by PACU nurse.
Outcomes: Outcomes
measured in this study
include: preoperative
anxiety, gastric pH and
residual volume,
postoperative nausea and
vomiting, and antiemetic
consumption.
19
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
Evidence Grid: Practice guidelines for preoperative fasting and the use of pharmacologic agents to reduce the risk of pulmonary
aspiration: application to healthy patients undergoing elective procedures
Authors of
Purpose of
Research elements:
Major findings/
Give strengths and
article/Yr
study/research
*Design *Population
findings relevant to your
weaknesses of this article
questions
*sampling method
project
for your project related to
Level of evidence
*sample size *description
validity, bias and
of methods/interventions (if
applicability
any) *instruments used
*outcomes measured
American society To enhance the
Design: Clinical practice
Recommended minimum
Strengths: The evidence
of
quality and
guideline
fasting times:
and guidelines were both
Anesthesiologists efficiency of
Population: Healthy patients Clear liquids—2 hours
externally and internally
Committee on
anesthesia care
of all ages undergoing
Breast milk—4 hours
peer reviewed, which
Standards and
To stimulate
elective procedures
Infant formula—6 hours
increases validity.
Practice
evaluation of
Sampling method: HandNon-human milk—6 hours
Weaknesses: The
Parameters
clinical practices
searches of published
Light meal—6 hours
recommendations published
To reduce the
literature and searches of
Fried, fatty foods or meat—8 in the guidelines were
LOE: Level I
severity of
electronic databases
hours
formulated based on expert
complications
Sample size: Total of 158
Benefits of preoperative
consensus, but were not
related to
articles contained findings
fasting include decreased
ranked. This may decrease
Ally Riddle
perioperative
directly related to at least one frequency and severity of
the applicability of the
pulmonary
of the evidence linkages
complications related to
guidelines.
aspiration of
pulmonary
aspiration
of
Bias may be present within
Description of
gastric contents
gastric contents and
the guidelines because some
interventions:
Instruments: To measure
minimization of perioperative articles evaluated were
strength of evidence, articles morbidity.
opinion articles.
were first divided into two
Potential harms of
categories: scientific or
preoperative fasting include
opinion-based evidence. The risk of dehydration and
scientific evidence articles
hypoglycemia.
were divided further into
supportive, suggestive,
equivocal, and insufficient
20
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
literature. The opinion-based
evidence articles were
further divided into expert
opinion, membership
opinion, or informal opinion.
To analyze the evidence,
literature was categorized
according to the proximity or
directness of the outcome to
the intervention. Articles
were ranked on a scale from
1-4. A ranking of 1
represents a direct
comparison either between
an intervention and a clinical
outcome, or between two
outcomes, and a ranking of 4
represents insufficient
evidence to evaluate and
cause-and-effect relationship.
Outcomes: Adverse
consequences of pulmonary
aspiration (pneumonia,
respiratory disabilities,
related morbidity), volume
and acidity of gastric
contents, adverse effects
(thirst, hunger, nausea,
vomiting), adverse outcomes
(pneumonitis, mortality),
length of hospital stay, costs
21
22
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
Evidence Grid: Role of preoperative carbohydrate loading: a systematic review
Authors of
Purpose of
Research elements:
Major findings/
article/Yr
study/research *Design *Population
findings relevant to your project
questions
*sampling method
Level of
*sample size
evidence
*description of
methods/interventions
(if any) *instruments
used
*outcomes measured
Bilku,
The purpose of Design: randomized
This review concludes that the
Dennison,
t his research
control trials,
administration of oral carbohydrate
Hall, Metcalfe, is to appraise
experimental design
drinks before surgery is probably
Garcea (2013). data from
Population: Any
safe because the drink leaves the
different
patient included in an
stomach in 90 minutes and does not
Level I
studies
article on pubmed
affect gastric acidity. It also may
evidence (it is
regarding the
have a positive influence on a wide
Sampling method:
a meta analysis safety and
Nonprobability
range of preoperative markers of
systematic
beneficial role
convenience sampling
clinical outcome.
review).
of preoperative Sample size: 1,445
INSULIN RESISTANCE
carbohydrate
patients who met
Six out of seven articles
loading in
inclusion criteria
demonstrated a specific reduction in
Alex
patients
insulin resistance following the use
Description of
Harmening
undergoing
methods/interventions: of preoperative carbohydrate loading.
surgery, and,
I think this is non
One study demonstrated no effect of
where possible, probability sampling
carbohydrate loading to insulin
make
because the review has sensitivity however this could be due
comparison
limited the population
to a type II error.
with placebo or to only patients who
GASTRIC EMPTYING:
traditional
were included in data
All five studies reported no
practice.
found on pubmed, not
difference in gastric emptying times
all patients undergoing
between the groups that received
surgeries that used
placebo or fasting from midnight to
Give strengths and
weaknesses of this article
for your project related to
validity, bias and
applicability
Internal validities of history
and selection bias are ruled
out because the review
excluded all trials that had
patients with with metabolic
disorders including diabetes
mellitus, ASA grade > 2
(American society of
anesthesiologists), gastrooesophageal reflux disease
and those with factors
affecting gastric emptying
(obesity, pregnancy, sliding
hernia of stomach, and
medications)  these
factors all increase risk of
aspiration. However this
still leaves the internal
threat of instrumentation
since the data in this review
was collected using
different methods.
23
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
carbohydrate loading.
The sampling method
used was any patient
included in articles on
pubmed that fell under
keywords ‘carbohydrate
loading’, ‘preoperative’,
‘surgery’, and ‘insulin
resistance’ and were
written before
September 2011
Outcomes measured:
The effect of
preoperative
carbohydrate loading on
insulin resistance,
gastric emptying,
gastric acidity, patient
wellbeing, immunity
and nutrition following
surgery.
groups that had intravenous glucose
or carbohydrate drinks.
GASTRIC ACIDITY: The three
studies included demonstrated no
difference in gastric acidity following
a carbohydrate drink compared with a
placebo, intravenous glucose or
fasting.
PATIENT WELLBEING:
Eight studies examined the impact of
carbohydrate loading to patient
wellbeing. The studies measured
wellbeing using the VAS (VAS
assesses thirst, hunger, anxiety,
depression, pain, tiredness, weakness,
inability to concentrate, mouth
dryness, and nausea) and the Beck
questionnaire that consists of 21
questions addressing symptoms such
as fatigue and irritability. It was
determined that preparation with
carbohydrate led to a significant
reduction in thirst, hunger, anxiety, and
malaise in two trials in which
carbohydrate loading was compared
with fasting and placebo.
IMMUNITY AND CLINICAL
OUTCOME: Two trials determined
there was no difference in the incidence
of postoperative infections in patients
using carbohydrate loading or with a
placebo group One study demonstrated
that preoperative treatment with
This study has external
validity because its results
can be generalized to any
patient receiving surgery.
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
carbohydrate drinks can lead to reduced
hospital stay compared to using
placebo or water.
NUTRITION:
No real significant differences.
DIABETIC PATIENTS: One trial
found that administration of
carbohydrate drink 180 minutes before
anesthesia in uncomplicated diabetes
patients is safe.
OVERALL:
**NO studies analyzed in the review
reported any adverse events following
ingestion of carbohydrate drinks or
proven aspiration during or after
surgery.**
24
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
25
Synthesis of Evidence
Standard practice in many surgical institutions states that patients undergoing
general anesthesia for a surgical procedure must begin fasting a minimum of six to eight
hours before the surgery or even as early as the night before. While these traditional
fasting protocols have been successful in the past decades, experts are beginning to
reconsider and suggest new protocols in place of fasting. As a starting place, shorter fasting
times, along with intake of water, black coffee, tea, or fruit juice without pulp was advised
for up to three hours before anesthesia induction, showing no increase in risk for
pulmonary aspiration (Oyama et al., 2011). These practices, which are being
recommended by anesthesiology societies in many developed countries, are now being
questioned for effectiveness. Wide ranges of studies are currently being done to test for a
new protocol: preoperative carbohydrate loading. Preoperative consumption of a
carbohydrate (CHO) drink are being recommended by The Enhanced Recovery After
Surgery (ERAS) critical care protocol (Oyama et al., 2011). Not only are these CHO drinks
providing decreased insulin resistance in the perioperative period, enhanced recovery and
reduced duration of hospitalization have also been reported. Patients receiving CHO drinks
preoperatively are showing decreased insulin resistance, decreased levels of preoperative
anxiety, fewer subjective feelings of thirst, hunger, and dry mouth, and no increase in
aspiration risk, as compared to those patients undergoing traditional overnight fasting.
A crossover-randomized study found that aggravation of insulin resistance could be
alleviated with adequate control of intraoperative blood glucose levels. If intraoperative
blood glucose levels are better controlled, then postoperative glucose control becomes
easier, leading to fewer infections and decreased hospital stay (Yatabe, Tamura, &
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
26
Yokayama, 2013). Preoperative CHO loading is a low cost, simple, and easy approach for
the improvement of insulin resistance, providing improved prognoses in perioperative
patients. In a systematic review of 16 randomized control trials, postoperative
complications, patient wellbeing, and length of hospital stay were all studied related to
preoperative CHO loading. Each of the 16 trials resulted in the same conclusion: a
preoperative CHO load could reduce postoperative insulin resistance (Shanley, 2009).
Reduced insulin sensitivity postoperatively has been associated with increased surgical
outcomes and enhanced patient recovery. While individual studies did not provide specific
evidence with regard to reduced length of stay, it was mentioned that the postoperative
regimen was the same for 13 of the 16 studies and a general enhanced recovery period was
seen (Shanley, 2009). These trials also noted that no adverse side effects arose as a result of
the preoperative CHO load, therefore suggesting that overnight fasting guidelines may need
to be questioned.
Many nutrients are important for recovering after surgery, especially trace elements
such as zinc (Zn) and copper (Cu), which play a large role in wound healing. A study
performed at a Japanese hospital evaluated the effects of an 18% CHO drink containing
trace elements on preoperative nutritional state and trace element levels are compared
with a conventional fasting protocol (Oyama et al., 2011). This treatment was reported to
suppress surgical stress-induced catabolism, thus attenuating insulin resistance and
improving patient outcomes postoperatively. Higher serum Zn concentrations were
observed in the patients who received the CHO drink before surgery, suggesting that
ingesting a CHO drink with trace elements may maintain Zn storage in the bone, muscle,
and the liver, aiding in wound healing postoperatively. Along with enhanced postoperative
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
27
recovery and shorter hospital stays, this study showed that CHO drink supplementation
before surgery can mitigate the stress experienced by patients preoperatively, thus
improving their perioperative experience as a whole (Oyama et al., 2011).
Anxiety can have detrimental effects on the body, especially one that has just
undergone surgery and is trying to heal itself. A study comparing three different types of
fasting protocols, overnight intravenous 5% glucose infusion, morning CHO-rich drink, and
overnight fasting, showed that anxiety was drastically decreased in both the glucose
infusion group and the CHO-rich drink group, compared to the fasting group (Helminen et
al., 2009). These reduced anxiety levels can lead to improved patient outcomes and shorter
hospital stays. Of the three fasting protocols, the CHO-rich drink showed less preoperative
hunger and thirst, and only mild mouth dryness. The fasting group, however, showed an
increase in thirst, hunger, mouth dryness, weakness, tiredness, and anxiety, along with
increased insulin resistance (Helminen et al., 2009). In a 2013 study where 40 patients
were randomly assigned to either a fasting group or a CHO loading group, lower anxiety
levels were reported by the 20 individuals receiving the CHO drink 2 hours before surgery,
as well as significantly lower levels of antiemetic consumption 24 hours after their
procedure. Participants in this group reported greater patient satisfaction and less anxiety
than those who fasted eight hours prior to surgery (Yilmaz et al., 2013).
In addition to all the medical benefits of CHO loading that have been found in the
previous studies, it is also pertinent to mention that no complication arose during surgery
in those patients who ingested the CHO drinks. Absolutely no adverse side effects were
found in any of the cases in which CHO loading was chosen over preoperative fasting. In a
randomized control trial performed in Turkey, 34 of its 70 participants received a CHO-rich
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
28
beverage the evening before surgery and two hours before the induction of anesthesia.
While these patients did not show any significant different in the serum insulin levels
compared to the 36 patients who underwent overnight fasting, these was also no difference
in gastric residue contents or gastric pH, suggesting that the practice of CHO-rich beverages
preoperatively was safe in terms of aspiration risk (Yagci et al., 2008). A double blind
randomized control trial consisting of 162 patients undergoing major elective abdominal
surgery, fatigue and discomfort were measured, as well as biochemistry, grip strength, and
duration of hospital stays (Mathur et al., 2010). Of the 76 patients who received the CHO
drink the night before and two hours before anesthesia was given, the length of stay was
slightly shorter than those who fasted overnight. Even though there were no significant
differences in postoperative fatigue, discomfort, grip strength, and biochemistry with the
CHO drink, no negative effects presented for these patients either. (Mathur et al., 2010).
Even in its early stages of research, it is apparent that carbohydrate loading
preoperatively can have significant medical benefits compared to the traditional protocol
of overnight fasting. Decreased insulin resistance helps to better control glucose levels
during and after surgery, leading to fewer infections and complications postoperatively, as
well as overall shorter hospital stays (Shanley, 2009). Lower anxiety levels preoperatively
enhance patient recovery postoperatively, leading to better surgical outcomes and higher
patient satisfaction (Yilmaz et al., 2013). Fewer reports of thirst, hunger, mouth dryness,
weakness, and tiredness play a role in boosting patient recovery times, leading to a shorter
duration of stay for surgical patients (Helminen et al., 2009). While all the possible benefits
of preoperative carbohydrate loading have yet to be discovered, the lack of adverse effects
shown in these patients leads us to further question the current standard protocol of
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
29
overnight fasting before surgery. Preoperative drink supplementation lends to many
advantageous outcomes for patients without increasing risk for aspiration or introducing
new adverse effects, possibly making it the new standard for preoperative intake protocol.
Appraisal of Evidence
A. The majority of the studies were well designed level I and II randomized control trials.
The level I study was a systematic review of randomized control trials, which established
a high level of evidence for this study. There are five level II studies including a doubleblind RCT, perspective randomized study, an experimental RCT, crossover randomized
order, and an RCT. There is also one level III study, which is a post-test experimental
design. This study is level III because there is no randomization in the trial.
B. The majority of the studies were consistent in that there are no adverse effects or
complications with preoperative carbohydrate loading. Several other studies stated that
there is no significant difference in gastric content and pH levels, and therefore suggests
that it is a safe procedure for aspiration risks. Most studies said that the patient’s overall
experience was improved with reduced anxiety and the Verbal Descriptive Scale scores
were lower. Some articles stated that patients who drank the carbohydrate rich beverage
usually reported less hunger and thirst compared to those who received IV carbohydrate
loading, but overall both methods decreased weakness and tiredness compared to the
fasting control group. A few studies also said that preoperative carbohydrate loading
could improve wound healing postoperatively and decrease infection; however, there is
no significant difference in the length of hospital stays. One of the studies reported no
substantial difference in the experimental and control group outcomes, suggesting that
carbohydrate loading did not prove to be beneficial or harmful for preoperative patients.
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
30
Overall, the majority of the studies found that carbohydrate loading can improve
postoperative insulin resistance in a low cost and simple way. There is a sufficient
quantity of studies that are consistent with the results to support these recommendations
C. Are there identified risks? The most important identified benefit for applying evidencebased practice recommendation is the improvement of postoperative insulin resistance.
With this improvement came less anxiety and overall patient satisfaction. In most studies
patients reported improved satisfaction and decreased thirst, hunger, fatigue, nausea and
vomiting. The studies reported that there are no identified risks or adverse effects of
preoperative carbohydrate loading.
D. None of the studies mentioned specific costs of preoperative carbohydrate loading.
However, one study mentioned that preoperative carbohydrate loading is a low cost and
simple method. Most of the studies agree that this is an easy approach to improving
insulin resistance.
Recommendations
Some studies show that preoperative carbohydrate loading can provide benefit to
patients over preoperative fasting. Articles found throughout the research make different
suggestions as to carbohydrate drinks and their effects. Listed are the different
recommendations found throughout the research along with a grade that determines the
benefit to patients.
It is recommended that a patient be given a preoperative CHO drink containing trace
elements before elective surgery to suppress preoperative metabolic fluctuations (Oyama
et al., 2011). This recommendation receives an A because the research is beneficial to
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
31
patients. However, it is a moderate level of certainty because subjects were grouped
according to morning and afternoon surgery, which would influence results. Carbohydrate
loading does not need to be given to patients having major abdominal surgery because
overall preoperative carbohydrate loading treatment did not improve fatigue and duration
of hospital stay for abdominal surgeries (Mathur et al., 2010). This recommendation would
receive a D because the beverage did not prove to benefit the patient’s malaise and
duration of stay. The research was a moderate level of certainty because the sample
patients were only chosen from two hospitals, not allowing for variations. In elective
surgery carbohydrate beverages should be given over intravenous glucose infusions
because the carbohydrate drinks showed to alleviate the feelings of tiredness and
weakness post operatively and decrease the feelings of hunger and thirst more than the
intravenous glucose (Helminen et al., 2009). The level of certainty of this study is high
because it is a randomized study with a large sample size making it unlikely that the results
will be affected by other studies. The score is a B because although the level of evidence is
high, it was not tested on various disease groups, and therefore, there may not be
substantial evidence for all patients. Carbohydrate beverages should be given pre
operatively to increase the serum glucose levels during surgery (Yagci et al., 2008). The
level of certainty for this research study is moderate because it is randomized to prevent
bias but it did not evaluate how pre operative carbohydrate loading will affect the overall
outcome. This recommendation gets a D because although the serum glucose levels
initially increased, by the time anesthesia was induced the effects had worn off, so it cannot
be determined if it would effect the patient post operatively. It is recommend that patients
be given carbohydrate beverages 4-8 hours before surgery to prevent intraoperative
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
32
hypothermia (Yatabe et al., 2013). This suggestion is given an I because the study was only
tested on rats. Therefore more research needs to be done to really see how the technique
would affect humans during surgery. The level of certainty is moderate because it is a
randomized control trial. To reduce the amount of post op antiemetic medication needed,
give a carbohydrate beverage prior to surgery (Yilmaz et al., 2013). This finding deserves a
C because the study only observed patients that underwent a laparoscopic cholecystectomy
therefore it does not prove that it will be beneficial to all patients.
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
33
References
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the risk of pulmonary aspiration: application to healthy patients undergoing elective
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Yagci, G., Can, M., Ozturk, E., Dag, B., Ozgurtas, T., Cosar, A., & Tufan, T. (2008). Effects of
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Yilmaz, N., Cekmen, N., Bilgin, F., Erten, E., Ozhan, M. O., & Cosar, A. (2013). Preoperative
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