Running head: PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
Does Preoperative Carbohydrate Loading Have Adverse Effects For Elective Surgery Patients
Compared to Overnight Fasting
Auburn University
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PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
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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 (Y. 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 (Y. Oyama et all, 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 et al, 2013). Preoperative CHO loading is a
low cost, simple, and easy approach for the improvement of insulin resistance, providing
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
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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 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 all, 2011).
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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 CHOrich 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 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
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
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aspiration risk (Yagci et all, 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 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.
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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
(Y. Oyama et
al, 2011). This recommendation receives an A because the research is beneficial to 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
PREOPERATIVE CARB LOADING VERSUS OVERNIGHT FASTING
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levels during surgery (Yagci et all, 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 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 cholecystctomy therefore it does
not prove that it will be beneficial to all patients.
References
Helminen, H., Vitanen, H., & Sajanti, J. (2009). Effect of preoperative intravenous carbohydrate
loading on preoperative discomfort in elective surgery patients. European Journal Of
Anesthesiology, 26(2), 123-127. doi:10.1097/EJA.0b013e328319be16
Mathur, S., Plank, L., McCall, J., Shapkov, P., Mcllroy, K., Gillanders, L., & … Parry, B.
(2010). Randomized controlled trial of preoperative oral carbohydrate treatment in major
abdominal surgery. The British Journal Of Surgery, 97(4), 485-494. doi:10.1002/bjs.7026
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Oyama, Y., Iwasaka, H., Shihara, K., Hagiwara, S., Kubo, N., Fujitomi, Y., & Noguchi, T.
(2011). Effects of Preoperative oral carbohydrates and trace elements on perioperative
nutritional status in elective surgery patients. Middle East Journal Of Anesthesiology,
21(3), 375-383.
Yagci, G., Can, M., Ozturk, E., Dag, B., Ozgurtas, T., Cosar, A., & Tufan, T. (2008). Effects of
preoperative carbohydrate loading on glucose metabolism and gastric contents in patients
undergoing moderate surgery: a randomized, controlled trial. Nutrition (Burbank, Los
Angeles County, Calif.), 24(3), 212-216.
Yilmaz, N., Cekman, N., Bilgin, F., Erten, E., Ozhan, M. O., & Cosar, A., (2013). Preoperative
carbohydrate nutrition reduces postoperative nausea and vomiting compared to
preoperative fasting. Journal of Research in Medical Sciences 18(10), 827-832.