Normal gastric emptying time of a carbohydrate-rich drink in elderly patients with acute hip fracture: a pilot study
Hellström et al. BMC Anesthesiology
Normal gastric emptying time of a carbohydrate-rich drink in elderly patients with acute hip fracture: a pilot study
Per M. Hellström 0
Bodil Samuelsson 1 2
Amer N. Al-Ani 3
Margareta Hedström 3
0 Department of Medical Sciences, Uppsala University , SE-75185 Uppsala , Sweden
1 Sophiahemmet University College , Stockholm , Sweden
2 Department of Clinical Sciences, Division of Orthopedics, Karolinska Institutet, Danderyd Hospital , Stockholm , Sweden
3 Department of Clinical Science and Technology (Clintec), Division of Orthopedics, Karolinska Institutet, Karolinska University Hospital , Huddinge , Sweden
Background: Guidelines for fasting in elderly patients with acute hip fracture are the same as for other trauma patients, and longer than for elective patients. The reason is assumed stress-induced delayed gastric emptying with possible risk of pulmonary aspiration. Prolonged fasting in elderly patients may have serious negative metabolic consequences. The aim of our study was to investigate whether the preoperative gastric emptying was delayed in elderly women scheduled for surgery due to acute hip fracture. Methods: In a prospective study gastric emptying of 400 ml 12.6% carbohydrate rich drink was investigated in nine elderly women, age 77-97, with acute hip fracture. The emptying time was assessed by the paracetamol absorption technique, and lag phase and gastric half-emptying time was compared with two gender-matched reference groups: ten elective hip replacement patients, age 45-71 and ten healthy volunteers, age 28-55. Results: The mean gastric half-emptying time in the elderly study group was 53 ± 5 (39-82) minutes with an expected gastric emptying profile. The reference groups had a mean half-emptying time of 58 ± 4 (41-106) and 59 ± 5 (33-72) minutes, indicating normal gastric emptying time in elderly with hip fracture. Conclusion: This pilot study in women with an acute hip fracture shows no evidence of delayed gastric emptying after an orally taken carbohydrate-rich beverage during the pre-operative fasting period. This implies no increased risk of pulmonary aspiration in these patients. Therefore, we advocate oral pre-operative management with carbohydraterich beverage in order to mitigate fasting-induced additive stress in the elderly with hip fracture.
Aspiration; Carbohydrate loading; Metabolism; Nutrition; Surgery
Over the last decade the guidelines for fasting in
preparation for immediate surgery have changed. Clear fluids
are now recommended within two hours before
induction of anesthesia in patients without known risks of
pulmonary aspiration . The guidelines for patients
considered to be at increased risk of delayed gastric
emptying, including trauma patients are however
unchanged . In hip fracture patients, the injury by itself,
including the acute mental stress, are factors that
theoretically can influence and delay gastric emptying. But
also other common factors in this patient group can
influence the gastric emptying rate, as for example, old age
, diabetes mellitus  renal insufficiency , and the
use of opioid analgesics .
Apart from being elderly and possibly suffering from
different comorbidities, patients admitted with a hip
fracture often are in a poor nutritional condition [6–8].
In spite of this, these patients are commonly kept fasting
in preparation for surgery and may later even be
reprioritized for surgery leading to further prolonged
fasting time. Hence, waiting times up to, and even beyond
24 h with continuous fasting is not uncommon .
During prolonged fasting, the patient suffers a risk of energy
depletion, with consequent harmful effects on general
health condition . To avoid this, the patient should be
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operated as early as possible after admission with adequate
energy substitution, primarily of proteins and
carbohydrates. Oral intake of 200 kcal carbohydrates triggers a
release of insulin similar to that after a light meal ,
which should be positive from a nutritional perspective.
As an alternative, if intravenous administration is chosen,
an equal amount of carbohydrates (i.e. 1000 mL 5%
glucose solution) causes only a limited insulin response [12,
13], which also means that the anabolic effect of insulin is
little. Preoperative carbohydrates provided in the form
of a beverage have been shown to have several other
benefits, such as reduced preoperative thirst, hunger
and anxiety . All these positive properties of
preoperative carbohydrate feeding instead of fasting should
be considered in the medical care of elderly patients
with a hip fracture.
The primary aim of the study was to investigate if
gastric emptying rate is delayed in elderly hip fracture
patients using a 400 mL carbohydrate-rich beverage as
nutritional supply. This was as compared to two
gendermatched comparator groups, one old and one young. The
secondary aim of the study was to study if the
carbohydrate-rich beverage could be administered within two
hours prior to surgery without risk of pulmonary
This prospective study was approved by the regional
ethics committee Karolinska Institutet (dnr 02–123),
and complies with the principles laid down in the
Declaration of Helsinki. The ClinicalTrials.gov
identifier is NCT02753010. Informed consent was given
after the patient had received written and oral
Ten patients, 77–97 years old (median 87), randomly
recruited among those admitted with an acute hip
fracture to Danderyd Hospital, Stockholm, Sweden,
were recruited during a period of 12 months.
Inclusion criteria were: female gender, age 75 years or
above, and hip fracture within 24 h of admission.
Exclusion criteria were: gastro-esophageal reflux disease,
peptic ulcer disease, gastrointestinal motility disorder,
pulmonary or cardiac disease, pharmacological treatment
with motility-stimulating agents such as dopamine
receptor blockers or macrolides, as well as previous long-term
opioids or acid inhibitory agents, or cognitive impairment
at the discretion of the investigator. Three patients did
not have any previous disease or medication. Two
suffered from diabetes mellitus, one substituted with
insulin, the other under treatment with oral anti-diabetic
drugs (glibenclamide). Two patients suffered from
hypothyroidism, which was substituted with thyroxine.
One patient had a history of stroke but was freely
The study was conducted in the morning hours during
fasting before surgery. Of the included nine patients, two
were given morphine intravenously in the morning
immediately prior to intervention (i.e. intake of beverage).
During the intervention, starting 180 min prior to surgery, the
patients had infusions with 5% glucose, and for diabetics
10% glucose 100 mL/h with insulin added to maintain
blood sugar below 10 mmol/L. All patients underwent
surgery under spinal anaesthesia according to routines.
No adverse events were observed peri-operatively. The
results were compared with two reference groups of 20
gender-matched subjects. One group consisted of 10
female patients (age 45–71) on the waiting list for elective
hip replacement surgery due to osteoarthritis . The
other group consisted of healthy female volunteers (age
28–55). All participants in the three groups were
nonsmokers and had normal body mass index.
Two-hundred mL of an iso-osmolar carbohydrate-rich
drink (50 kcal, 12.6% carbohydrates per 100 mL, pH 5.0,
Nutricia Preop; Numico; Zoetermeer, The Netherlands),
was first given. Then, 1.5 g of paracetamol dissolved in
100 mL water was taken and thereafter another 200 mL
of the carbohydrate-rich drink resulting in a total
volume of 500 mL. This beverage has been approved by the
Swedish Medicines Agency for use close to surgery.
In the two reference groups, the beverage was given to
the patients in an upright sitting position. In the
experimental group, due to the fracture-related pain, a
halfsupine position was allowed. If needed, additional
intravenous morphine was allowed according to usual
routines. Vomiting and nausea were registered.
Gastric emptying rate was assessed by the paracetamol
absorption technique: after oral ingestion, the absorption
of paracetamol is used as an indirect measure of the rate
of gastric emptying. Using blood samples, plasma was
obtained for measurement of paracetamol concentration
at 0, 15, 30, 60, 120 and 180 min after the total intake of
beverage and paracetamol solution.
The paracetamol absorption technique has been
described and validated earlier, and shown to correlate
well with other methods of measuring gastric emptying
[16–18]. The method was adapted from that described
by Näslund et al. , and the concentration of
paracetamol (acetaminophen) was measured by HPLC
(Sigma-Aldrich, St. Louis, MO; standard UC448) with a
coefficient of variation of 5%. A statistical limit for
significance was set at 5%.
Gastric emptying was compared between the groups
using the lag phase, half-emptying time and complete
emptying. The lag phase was defined as emptying of 2%
of gastric contents, whereas gastric half-emptying time
(T50) was defined as the period from the end of
beverage intake with paracetamol until 50% of gastric
emptying was achieved, and complete emptying as the time
point when no more absorption of paracetamol occurred
. The gastric emptying profile was estimated after
conversion of plasma paracetamol concentration values
to cumulated values, i.e. total absorption of the drug. In
this way we obtained a gastric emptying curve from 0%
to 100% adapted to a third-order polynomial. The
sample size n = 10 was calculated based on a ±20%
minimum detectable effect and a statistical significance of
95%. For statistical evaluation of differences between the
groups, the Kruskal-Wallis test with Dunn’s post hoc test
was used. Results are given as medians with minimum
and maximum values as well as means with the 95%
confidence interval within parenthesis.
All 10 patients in the acute hip fracture group were
fasted from midnight, implicating at least eight hours
strict fasting before the oral carbohydrate-loading
beverage was taken. Nine of the ten included patients were
analyzed; one patient excluded due to incidental
morphine treatment with concomitant nausea and vomiting.
The gastric emptying was comparable between the
three groups with a typical curve shape showing an
initial lag phase, followed by an emptying phase and finally
tailing-off with complete emptying of the stomach at
180 min. The lag phase before emptying took place was
not delayed in any of the groups that underwent surgery
and similar to the healthy controls (Table 1). After onset
of the emptying process the gastric emptying rate was
similar in all groups as verified by the half-emptying
time (T50). In the acute hip fracture group, the gastric
Table 1 Gastric half-emptying time of 400 mL carbohydrate-rich
drink in three groups of women
Lag phase, minutes, 1 (0–7)
half-emptying time was 57 ± 5 (39–82) minutes. In the
two reference groups the half-emptying times were 58 ± 4
(41–106) minutes in the group of females scheduled for
hip replacement, and 58 ± 5 (33–72) minutes in the
control group of healthy female volunteers (age 28–55)
(Table 1, Fig. 1). The gastric emptying profile displayed
the expected slightly sigmoidal curve representing a
thirdorder polynomial function according to which calculations
of lag phase and T50 were made (Fig. 2). None of the
patients experienced any acid regurgitation or aspiration. No
other adverse effects of the intake of the beverage was
In this pilot study we have evaluated gastric emptying in
a comparably old and fragile group of patients admitted
to hospital with an acute hip fracture. The results were
evaluated against two gender-matched control groups;
one of similar age range, another at younger age. Our
data show no differences between the groups, neither of
gastric emptying rate as evaluated by gastric
halfemptying time, nor by gastric emptying profile which
showed an expected curve form. These findings support
the hypothesis that gastric emptying is not deranged
even in comparably old patients. Hence, there is no
motivation for an overnight fast in order to diminish the
risk of gastric aspiration during anesthesia and surgery.
With the ambition to ensure safe surgical procedures,
commonly used guidelines recommend a prolonged
preoperative fasting of at least 6 h as delayed gastric
emptying in the elderly is presumed. This is based on the
assumption that not only pain and stress caused by the
injury, but also to high age and comorbidity should slow
gastric emptying .
In our study group, the patients were elderly women
with more than half of them over 90 years of age, and
even though, we found no signs of slow gastric emptying
even at high age. In studies of healthy subjects, the
association between high age and delayed gastric emptying is
59.6 (50–69.2) 58.6 (50.2–67.0)
Gastric emptying assessed by the paracetamol absorption technique. Lag
phase, emptying of 2% of gastric contents; T50, gastric half-emptying
time, 50% emptying of contents. Carbohydrate beverage: 50 kcal, 12.6%
carbohydrates/100 mL, pH 5.0 (Nutricia Preop; Numico; Zoetermeer, The
Netherlands). CI, confidence interval
Fig. 1 Boxplots of gastric half-emptying time using the paracetamol
absorption technique in three groups of women: Elderly women
with acute hip fracture (n = 9), women with osteoarthritis scheduled
for elective hip replacement (n = 10) and healthy female volunteers
Fig. 2 Individual gastric emptying profiles of nine elderly women
with acute hip fracture. In all patients the gastric emptying curve
fulfilled requirements of a third-order polynomial sigmoid curve by
which gastric lag phase, half-emptying times and complete emptying
were calculated (see Table 1)
inconsistently reported [2, 15, 20–23]. In a previous
study, we reported increased gastric emptying rate of
solid food in women over 50 years of age as compared
to young women. This seems to hold true even up to
80 years of age . Opposed to this, studies in younger
women below age 50 have reported slower gastric
emptying rate with solids [16, 20, 23]. In our hands all
three groups of women had similar gastric emptying rate
suggesting a similar gastric emptying of a liquids, such
as a carbohydrate beverage.
In this patient category of elderly women concomitant
drug treatment with opioids as pain-killers may prolong
gastric emptying rate, thereby putting the patient at risk
of pulmonary aspiration [5, 20]. In this study two of the
three patients who received opioids pre-operatively
displayed normal gastric emptying rates, whereas one
patient suffered from nausea and vomiting and was
excluded from the study. This patient also had
considerable comorbidity with chronic renal failure and anemia,
risk factors for delayed gastric emptying . Diabetes
mellitus has also been considered as a major cause of
gastric emptying comprising 30-50% of individuals with
diabetes [24, 25]. However, this complication seems to
be confined to the gastric emptying of solids and not
liquid contents . In line with this, among the patients
in our study comorbidities such as hypothyroidism,
diabetes, and even renal failure had no effect on the
gastric emptying rate. In practical terms, our results
indicate that there is a reason for concern when
opioids are used preoperatively, but the risk of aspiration
seems to be limited and nausea may caution against
the risk of aspiration. It therefore seems that in the
majority of acute hip fracture patients gastric
emptying of liquids is not affected in the pre-operative
phase. This opens the possibility of using a
carbohydraterich beverage in order to delimit the stress-related
metabolic derangement induced by prolonged fasting and
should be considered for optimizing post-surgical recovery
in the elderly.
Gastric emptying of a carbohydrate-rich beverage has
previously been studied in hip fracture patients. A
volume of 200 mL has been given close to induction of
anesthesia and the emptying rate as well as risk of
pulmonary aspiration evaluated. Even though the study
design was different from ours, findings were similar and
none of the patients showed delayed gastric emptying
and no pulmonary aspiration occurred . Moreover,
to improve the quality of care for hip fracture patients,
some surgical centers have now decided to deviate from
strict fasting routines, also in elderly patients. Hence, a
recently published study employing a multimodal
optimization package for hip fracture patients claim that
all patients were allowed clear fluids up to 3 h before
This limited pilot study cannot exclude the risk of
incidental drawbacks such as pulmonary aspiration and
vomiting in large series of patients in routine medical
care. However, our study as well as previous reports 
indicate that this is not the case. Albeit, special care has
to be taken to patients with agonizing nausea, especially
after opioid use, who may be at risk.
We did not include a specific pain scoring to relate to
the gastric emptying as this was not crucial for testing our
hypothesis. Individual variations with regard to pain in
this patient population have been reported in the
literature, and the pain pattern reported in the current study
was considered to be representative for a normal hip
fracture population. It should be noted that although two of
the patients in our study received opioids that usually are
considered to slow gastric emptying, we could not find
this to be the case in these two individuals.
Taken together, this pilot study of elderly women with
an acute hip fracture showed no evidence of prolonged
gastric emptying time or incidents of aspiration. This
means that a carbohydrate-rich beverage could be given
close to surgery in order to prevent a prolonged
metabolically deleterious fasting period which could delay the
ALF: Avtal om läkarutbildning och forskning (i.e. agreement on medical doctors’
training and research in Sweden); Dnr: Diary number; HPLC: High performance
liquid chromatography; MO: Missouri; T50: Gastric half-emptying time
Financial support was provided through the Regional Agreement on Medical
Training and Clinical Research (ALF) between Stockholm County Council and
Karolinska Institutet, Uppsala University, Swedish Orthopedic Association,
King Gustaf the V and Queen Victoria’s Freemasons Foundation, The National
Board on Health and Welfare, Sweden, and Sophiahemmet Foundation.
Availability of data and materials
Primary data and materials for the study are available through prof
Per M. Hellström, Uppsala University, where primary data also are filed.
BS collected data, participated in design, analyses, interpretation of data and
drafted the manuscript. PH carried out the design, performed the statistical
calculations, participated in analyses and interpretation of data and critically
reviewed the manuscript. AAA participated in analyses and interpretation of
data. MH participated in the study design, analyses and interpretation of
data, and drafted the manuscript. All authors read and approved the final
Ethics approval and consent to participate
The study was approved by the regional ethics committee at Karolinska
Institutet (dnr 02–123), and complies with the principles laid down in the
Declaration of Helsinki. The ClinicalTrials.gov identifier is NCT02753010.
Informed consent to participate in the study was given after the patients
had received written and oral information.
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