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 [15
]. 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
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 3–4 hours.
The type of nutrition administered depended on the age of the patient: in children under 2–3 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 2–3 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 0.5–1 ml/kg per hour, with increases of 0.5–1 ml/kg every 3–4 hours if the gastric residue was less than 25% of the volume administered, until a calorie intake of 60–100 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 Chi-square 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.