Postpyloric enteral nutrition in the critically ill child with shock: a prospective observational study
Postpyloric enteral nutrition in the critically ill child with shock: a prospective observational study
Jess Lpez-Herce 1
Santiago Menca 1
Csar Snchez 1
Maria J Santiago 1
Amaya Bustinza 1
Dolores Vigil 0
0 Preventive medicine department, Hospital General Universitario Gregorio Maranon , Madrid , Spain
1 Pediatric intensive care unit, Hospital General Universitario Gregorio Maranon , Madrid , Spain
Background: Tolerance to enteral nutrition in the critically ill child with shock has not been studied. The purpose of the study was to analyze the characteristics of enteral nutrition and its tolerance in the critically ill child with shock and to compare this with non-shocked patients. Methods: A prospective, observational study was performed including critically ill children with shock who received postpyloric enteral nutrition (PEN). The type of nutrition used, its duration, tolerance, and gastrointestinal complications were assessed. The 65 children with shock who received PEN were compared with 461 non-shocked critically ill children who received PEN. Results: Sixty-five critically ill children with shock, aged between 21 days and 22 years, received PEN. 75.4% of patients with shock received PEN exclusively. The mean duration of the PEN was 25.2 days and the maximum calorie intake was 79.4 kcal/kg/day. Twenty patients with shock (30.7%) presented gastrointestinal complications, 10 (15.4%) abdominal distension and/or excessive gastric residue, 13 (20%) diarrhoea, 1 necrotising enterocolitis, and 1 duodenal perforation due to the postpyloric tube. The frequency of gastrointestinal complications was significantly higher than in the other 461 critically ill children (9.1%). PEN was suspended due to gastrointestinal complications in 6 patients with shock (9.2%). There were 18 deaths among the patients with shock and PEN (27.7%). In only one patient was the death related to complications of the nutrition. Conclusion: Although most critically ill children with shock can tolerate postpyloric enteral nutrition, the incidence of gastrointestinal complications is higher in this group of patients than in other critically ill children.
Enteral nutrition is safe and effective in most critically ill
children [1,2]. The early initiation of enteral nutrition
may preserve mechanical and immunological gut barrier
function, stimulating intestinal trophism, and reducing
bacterial translocation and the incidence of sepsis and
multisystem failure . It has few side effects. However,
oral or nasogastric feeding is sometimes poorly tolerated
by patients on mechanical ventilation, due to the reduced
gastric motility secondary to the administration of drugs
or to the disease itself, with the onset of abdominal
distension and the accumulation of gastric residues, leading
to a risk of pulmonary aspiration [4,5]. Transpyloric
enteral nutrition is used in the most severely ill patients,
who have a lower tolerance to gastric nutrition, and in
patients with deep sedation and muscle relaxation, in
both adults [6,7] and children [8-10].
However, enteral nutrition is not prescribed in many
patients with shock, or only a low feed volume is
administered to keep the bowel active. Enteral nutrition
increases splanchnic metabolic demands, which may lead
to oxygen and/or energy mismatch when the gut is
hypoperfused . Shock leads to a rapid and marked reduction
in splanchnic perfusion, altering tolerance to enteral
nutrition, and can induce functional and structural
gastrointestinal alterations and systemic complications .
For this reason, critically ill patients who develop shock
are often treated with parenteral nutrition. However, a
number of studies have shown that adult patients in the
postoperative period of cardiac surgery, with
haemodynamic disturbances and/or requiring inotropic support,
tolerated enteral nutrition adequately [13,14]. We have
found no studies which have prospectively analysed the
tolerance and adverse effects of enteral nutrition in
children with shock. This has been the objective of the present
Patients and methods
A prospective, observational study was performed which
included all the critically ill children admitted to the
Paediatric Intensive Care Unit who received postpyloric
enteral nutrition (PEN). Patients with shock were
compared with the rest of critically ill children. The study was
approved by the Institutional Review Board.
Shock was defined as a mean blood pressure > 2 SD below
the normal level for age after more than 20 ml/kg of
volume infusion and/or dopamine > 15 mcg/kg/min and/or
adrenaline > 0.3 mcg/kg/min).
The indications to PEN were children on mechanical
ventilation, those with an altered conscious level only
responding to noxious stimuli, respiratory failure without
mechanical ventilation, children at risk of aspiration, and
in those who did not tolerate gastric nutrition. The
postpyloric tube was inserted by the nursing staff following a
protocolised method, by blind insertion or with
placement of the patient in a lateral decubitus position, with air
insufflation . Confirmation of the position of the tube
was initially performed by aspiration and measurement of
the pH (it was considered that the tip of the tube was
probably in the duodenum if the pH of the aspirate was
equal to or higher than 6), and this was subsequently
confirmed radiologically. All the tubes were situated between
the 1st and 4th portions of the duodenum. A second tube
was inserted via the same nasal orifice for drainage of the
gastric contents and for measurement of the gastric
residue every 34 hours.
The type of nutrition administered depended on the age
of the patient: in children under 23 years, an infant
formula was administered (700 kcal/L, 18 g protein/L); this
was substituted by protein hydrolysate in patients with
milk-protein intolerance or a suspicion of intestinal
damage. Calorie supplements in the form of dextrin-maltose,
medium chain triglycerides, or cereals were added in
some patients. In children over 23 years of age, isocaloric
(1.2 kcal/ml), normoproteic (26 g proteins/L) paediatric
liquid formulae were administered. The alimentation was
started at a rate of 0.51 ml/kg per hour, with increases of
0.51 ml/kg every 34 hours if the gastric residue was less
than 25% of the volume administered, until a calorie
intake of 60100 kcal/100 kcal metabolised/day
according to the Holiday formula, was achieved.
The following data were gathered prospectively: age, sex,
weight, diagnosis, surgery, previous parenteral nutrition
and its duration, indications for PEN, duration of
admission before starting at PEN, maximum volume and
calories administered, duration of the PEN, indications for
withdrawal, and subsequent type of nutrition. The doses
of vasoactive drugs, sedatives, and muscle relaxants
administered during the PEN, the use of mechanical
ventilation and its duration, altered liver function (defined as
an elevation of the AST to more than twice the normal
value or of the bilirubin above 2 mg/dl), and nosocomial
pneumonia after starting the PEN (defined according to
CDC criteria), were also recorded. The complications of
enteral nutrition analysed were: significant abdominal
distension, residues of the nutrition in the gastric aspirate
with a volume greater than fifty percent of the volume
administered in the previous 4 hours, diarrhoea, and
necrotising enterocolitis (defined by abdominal distension,
intestinal haemorrhage, and ultrasound and radiological
findings). Failure of the enteral nutrition was considered
to have occurred when complications secondary to the
nutrition developed which required its interruption.
The characteristics of the nutrition were compared
between the patients with shock and the remainder of
critically ill children who received PEN during the study
period. The statistical analysis was performed using the
SPSS version 12 statistical programme, expressing
quantitative variables as means and standard deviations and
qualitative variables as percentages. Uni- or bivariate
analyses were used to study statistical associations. The
Chisquare test was used for the analysis of qualitative
variables and Fisher's exact test for quantitative variables when
n was less than 20 or when any theoretical value was less
than 5. Student's t test was used to compare quantitative
variables between independent groups. Significance was
taken as p < 0.05.
Postpyloric enteral nutrition was administered to 526
critically ill children, 65 (12.3%) of whom presented shock.
Patients with shock had a mean (SD) age of 37.6 (54.4)
months (range 21 days-22 years) and weight of 14.6
(14.9) kg (range 2.870 kg). Thirty-three children
(50.8%) in this group were under 1 year of age and 44
patients (67.6%) were male. The patients' diagnoses are
summarised in Table 1. The indication for PEN was
mechanical ventilation in 64 patients (98.5%) and
intolerance to gastric nutrition in 1 (1.5%).
A comparison of the characteristics of the children with
shock and the other critically ill patients who received
PEN is presented in Table 2. The children with shock had
a significantly higher age and weight than the other
critically ill children who received PEN. A significantly higher
percentage of patients with shock required dopamine,
adrenaline, and milrinone, and the dose of adrenaline
and dopamine was also significantly higher in these
children than in the other patients (Table 2). The percentage
of patients with shock requiring continuous infusions of
sedatives (midazolam and fentanyl) and muscle relaxants
(vecuronium) was significantly higher than in the other
critically ill children. The doses of midazolam and
fentanyl were also significantly higher in children with shock.
The children with shock presented a significantly higher
incidence of acute renal failure than the other of children.
Hepatic alterations were also more common in this group,
though the difference did not reach statistical significance.
The mortality among patients with shock was higher than
in the other children (Table 2).
The characteristics of the nutrition are presented in Table
3. Parenteral nutrition was administered to 21.5% of children with shock prior to starting the enteral nutrition. This percentage of children receiving parenteral nutrition
Postoperative cardiac surgery
Other medical diagnoses
prior to the PEN and the duration of this nutrition were
similar in the two groups of patients. The time of starting
the PEN and the percentage of patients in which the PEN
was started within the first 48 hours after the patient's
admission to the PICU did not differ significantly
between the children with shock and the other critically ill
The calorie intake received on the first day of PEN was
lower in the children with shock than in the other
children but the differences were not statistically significant.
There were no differences between the two groups
regarding the maximum calorie intake achieved. The duration of
the PEN was significantly longer in the children with
shock than in the other children (Table 3).
Thirty patients with shock (30.7%) presented
gastrointestinal complications during PEN. A significantly higher
rate that in the other critically ill children. Specifically, the
incidence of abdominal distension and/or gastric residues
and the incidence of diarrhoea in the children with shock
were significantly higher than in the remainder of the
patients (Table 3). No relationship was found between
the incidence of digestive tract complications and age,
weight, diagnosis, early (first 48 hours) or late
administration of the PEN, volume of nutrition, or the calories
administered. Definitive withdrawal of the nutrition due
to digestive tract complications (duodenal perforation
caused by the transpyloric tube, necrotising enterocolitis,
gastrointestinal bleeding, diarrhoea, or abdominal
distension) was only necessary in 6 children. Death was related
to a mechanical complication of the nutrition (duodenal
perforation) in 1 patient.
Few studies have evaluated the safety and efficacy of
enteral nutrition in patients with shock [13,14,16]. Our
study shows that children with shock can be fed by enteral
nutrition although the incidence of complications is
higher than in other critically ill children. However, the
heterogeneity of the population studied, with a wide age
range and very diverse diagnoses, is a limitation as it
complicates the analysis of the results. In humans, feeding
produces an increase in cardiac output and vasodilatation
of the mesenteric arteries, maintaining the balance
Number and percentage of patients
Table 2: Comparison of the clinical characteristics of the children with shock and the other critically ill patients who received
Adrenaline (median, range)
Milrinone (median, range)
Fentanyl (median, range)
Vecuronium (median, range)
Maximum dose of drugs during nutrition. Units: mcg/kg/min (dopamine, adrenaline, milrinone, midazolam); mcg/kg/h (fentanyl, vecuronium)
between oxygen delivery and consumption. However,
splanchnic oxygen delivery is reduced in shock while
splanchnic oxygen consumption remains unaltered .
In this situation, feeding can exacerbate the altered oxygen
balance, leading to gastrointestinal complications and, on
rare occasions, small bowel necrosis [17-20]. However,
Rokyta et al showed that a low-dose post-pyloric enteral
nutrition in septic patients led to a hyperaemic systemic
and hepatosplanchnic response with no alteration of
energy balance or oxygen kinetics. The increase in total
hepatosplanchnic blood flow was proportional to the
increase in the cardiac index . Similar effects were
found by Revelly et al in cardiac patients .
Patients with shock present other risk factors that could
impair enteral tolerance. First, they require the
administration of high doses of vasoactive drugs. Adrenaline and
high doses of dopamine can reduce intestinal perfusion
and impair the tolerance to nutrition. However, if
adrenaline and dopamine increase cardiac output, splanchnic
perfusion could be improved. King et al, in a retrospective
study on 55 critically ill children who received inotropic
Table 3: Comparison of the characteristics of nutrition between the children with shock and the other critically ill patients who
received postpyloric nutrition
drugs, found that many patients tolerate enteral nutrition
well . Our experience supports this finding .
Berger et al found that enteral nutrition was well tolerated
in adults with haemodynamic failure after cardiac surgery
. However, enteral nutrient delivery was significantly
negatively related to the dose of dopamine and
noradrenaline . Probably, the effect of vasoactive drugs will
depend on the dose and the haemodynamic situation in
An additional aspect is that children with shock have a
higher incidence of acute renal failure and mortality than
other critically ill children . Critically ill patients with
acute renal failure can tolerate enteral nutrition although
the incidence of gastrointestinal complications is higher
[24,25]. Finally, bowel motility is decreased in critically ill
patients  and may be further reduced by high doses of
sedatives and muscle relaxants, impairing enteral
tolerance. These drugs are administered to patients with shock
more frequently and at higher doses than in other
critically ill children; despite this, most children with shock in
our study presented an adequate tolerance to postpyloric
In the majority of our patients, shock did not delay the
initiation of enteral nutrition. Berger et al found that
enteral nutrition is possible in the first postoperative week
after cardiac surgery in adults . However, in that study
enteral, nutrition provided an insufficient energy delivery
and the patients required additional parenteral nutrition
. In our study, the energy delivery administered on the
first day of nutrition in patients with shock was lower than
in the other children, though there were no significant
differences in the maximum calorie intake achieved in the
two groups. There are no well planned prospective studies
studies that have analysed whether children in shock
require the same calorie intake as other critically ill
The incidence of abdominal distension, vomiting, and an
excessive gastric residue in our children was of 15%. The
frequency varies between 20% and 70% in critically ill
adults receiving enteral nutrition [4,5]. The presence of an
excessive gastric residue and abdominal distension are
due to the existence of gastrointestinal paresis with a
slowing of intestinal transit. The higher doses of dopamine,
sedatives, and muscle relaxants used in our children with
shock may be partly responsible for this complication.
The incidence of diarrhoea was similar to that found in
the critically ill adults [4,5], but was significantly higher
than in the other critically ill children. Shock produces
diarrhoea because it impairs small bowel function and
permeability. However, diarrhoea in our patients was
generally mild and improved after modification of the diet.
Definitive withdrawal of the PEN due to digestive tract
complications was required in only 6 patients with shock.
Only 2 severe gastrointestinal complications occurred.
One patient suffered duodenal perforation due the
insertion of the transpyloric tube and other infant developed
We conclude that most children with shock can receive
transpyloric enteral nutrition, although the incidence of
digestive tract complications is higher than in other
critically ill patients. For this reason, enteral nutrition must be
used with caution in patients with shock. Physicians must
monitor the patients closely for the onset of
gastrointestinal complications (abdominal distension, excessive
gastric residue, bloody diarrhoea, or dilated bowel loops or
intramural gas on radiographic studies). If gastrointestinal
complications develop and do not improve with a
reduction or modification or the diet, enteral nutrition must be
suspended and substituted by parenteral nutrition.
JL-H: conceived the study and participated in the design,
data collection and analysis, and drafting of the
SM, CS, MJS, and AB participated in the design, data
collection and analysis, and drafting of the manuscript.
DV participated in the design of the study and performed
the statistical analysis.
All authors read and approved the final manuscript.
To the nurses and doctors of the Paediatric Intensive Care Department for
their collaboration in performing this study.
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