Management of abdominal distension in the preterm infant with noninvasive ventilation: Comparison of cenit versus 2x1 technique for the utilization of feeding tube

Abstract

BACKGROUND:

Preterm infants are fed by orogastric / nasogastric tube until they reach maturation and coordination of sucking, swallowing and respiration at approximately 32–34 weeks of corrected age. While being on non-invasive ventilation (NIV), they frequently present abdominal distension. Currently at our institution two techniques are used for the management of abdominal distension in preterm infants fed by bolus via orogastric tube: cenit and 2 x 1.The aim of this study was to compare the proportion of preterm infants presenting NIV-associated abdominal distension with each of these techniques.

STUDY DESIGN:

We conducted a randomized clinical trial including infants of < 36.6 weeks of gestation and < 1500 g of birth weight who were admitted to our NICU during the period of April 1, 2016 to April 1, 2018 and received NIV. The presence of abdominal distension > 2 cm was the primary outcome. Secondary outcomes were presence of reflux, regurgitation, oxygen saturation during feeding and days to reach full feedings. Feeding tube drainage, stool characteristics and the use of prokinetics were confounding variables.

RESULTS:

A total of 97 patients were included. Forty-six in the cenit group and 51 in the 2 x 1 group. There was no difference in the proportion of infants with abdominal distension > 2 cm between groups. Oxygen saturation during feeding at volume of 150 ml/kg/day was higher in the cenit group with statistical significance.

CONCLUSION:

The use of cenit or 2 x 1 technique in preterm infants with NIV did not improve abdominal distension or other indicators of feeding tolerance.

Keywords

prematurity feeding techniques abdominal distension

Abbreviations

NIV

Non-invasive ventilation

Orogastric

Nasogastric

CPAP

Continuous positive airway pressure

Nasal ventilation

NFV

Nasopharyngeal ventilation

SiPaP

Infant flow -variable flow CPAP

HFNC

High flow nasal cannula

Standard deviation

WOG

Weeks of age

1 Background

Adequate nutritional management impacts the clinical outcome of preterm infants, enhancing survival in short term and growth and neurodevelopment in long term [1]. Early initiation of enteral feeding in preterm infants < 1500 g promotes intestinal maturation, favours feeding tolerance and shortens time to reach full enteral feeding, which diminishes exposure to parenteral nutrition limiting its infectious and metabolic risks [2]. Moreover, faster weight gain has been reported in infants who initiate enteral feedings sooner [3]. Human milk enteral feeding with progressive small increases (15–20 ml/kg/d) has not demonstrated a reduction in the incidence of necrotizing enterocolitis or death in preterm infants < 1500 g, including those with fetal growth restriction and altered flow in placental vessels diagnosed by prenatal ultrasound, compared to increases of 30–40 ml/kg/d [4].Therefore clinicians should promote early introduction of enteral feeding and advancing according to tolerance [5]. Preterm infants are fed by nasogastric/orogastric tube until full development of sucking, swallowing and breathing coordination around 32–34 weeks of corrected age [6 –9]. In gavage feeding, milk is delivered through orogastric/nasogastric tube as intermittent bolus in 10–20 minutes every 2–3 hours or continuously with an infusion pump [10, 11]. The first report of continuous feeding was published in 1972. Nowadays, this technique is frequently used in preterm infants with birth weight < 1300 g [11, 12]. In clinical practice, intermittent feeding is the most common type of enteral feeding. However, there is not enough evidence to determine the best feeding method for low birth weight premature infants [13, 14]. Current data does not provide enough evidence to support the use of transpyloric tube over nasogastric/orogastric position. Moreover, increased risk of motility disorders with the use of transpyloric tube has been reported [15]. Non-invasive ventilation (NIV) is more frequently used as the first line treatment for respiratory distress in the preterm infant in order to decrease the complications associated with invasive ventilation [16]. In the last two decades, the widespread practice of early extubation to CPAP further complicates clinical decision making due to benign gaseous distension of the bowel in a setting of reduced motility [10]. Significant abdominal distension has been observed after 4–7 days of CPAP use. Radiological findings include dilatation of stomach, small bowel and colon without wall thickening, free air or pneumatosis intestinalis. Feeding intolerance is frequent in infants who are supported with CPAP, however, it does not contraindicate feeding or CPAP use [17]. Improvement in sensors and interfaces has resulted in the introduction of new types of non-invasive ventilation, such as nasal intermittent positive pressure ventilation (NIPPV), infant flow- variable flow CPAP (SiPAP) and nasopharyngeal ventilation (NFV) among others [18]. Reported adverse events vary from abdominal distension and feeding intolerance to necrotizing enterocolitis. Even the routine use of ventilation via nasal prongs or mask is associated with an increased risk of intestinal perforation in hospitalized newborns [19 –21]. In our institution (Instituto Nacional de Perinatología), two techniques of gavage feeding are used in the preterm infant < 1500 g with non-invasive ventilation: the cenit technique and 2 x 1 technique [21]. There is lack of evidence to recommend either of these techniques. The aim of this study was to compare the proportion of preterm infants presenting NIV-associated abdominal distension > 2 cm with each of these techniques.

2 Study design

We conducted a randomized clinical trial including preterm infants of < 36.6 weeks of gestation and < 1500 g of birth weight who were admitted to our NICU during the time period of April 1, 2016 to April 1, 2018 and were noninvasively ventilated (CPAP, NFV, NIPPV, SiPAP, HFNC). The aim of this study was to compare the presence of abdominal distension > 2 cm with each of these techniques. Patients with enteral fasting, invasive mechanical ventilation or those without ventilatory support were excluded. Patients who were transferred to another institution, those in which non-invasive ventilation was withdrawn or fasting was started during the study period were discarded. Sample size was calculated with StatCalc program, with a p value of 0.05 and a power at 80%, to demonstrate a decrease in the proportion of patients with abdominal distension > 2 cm from 30 to 10% yielding a number of 63 patients per group. Independent variable was orogastric tube technique (cenit vs 2 x 1), primary outcome variable was abdominal distension > 2 cm. Demographic variables were gestational age, weight and gender. Noninvasive ventilation type was registered and maintained during the study period. Secondary outcome were the presence of reflux, regurgitation, oxygen saturation during feeding and days to reach full feedings. Confounding variables were prokinetic use (metoclopramide, cisapride, clebopride), type of milk (human, formula, mixed), stool characteristics, orogastric tube drainage characteristics and clinical abdominal findings. The study was approved by the Committee of Research, Ethics and Biosafety of our institution.

To measure abdominal distension, abdominal circumference was obtained. A fiberglass tape measure (Seca 201) was placed at the iliac crest level posteriorly and 1 cm above umbilicus anteriorly, with the baby in a supine totally horizontal position. Abdominal circumference was measured before feeding and 1 hour post feeding. Data was collected when feeding was started, when volume of feedings was 50, 100 and 150 ml/kg/day. (Start, 25, 50 and 100% of feeding plan). Cenit technique consists of placing an OG tube (measuring the distance to be introduced from the nose to the earlobe and from the earlobe to the middle point between xiphoid appendix and the umbilicus), lifting the external tip of the tube emerging from the mouth and attaching it to the upper cover of the isolette. In this technique, the OG tube remains open permanently and remains lifted. In the 2 x 1 technique, the OG tube remains aside the baby, closed for two hours after feeding and opened for one hour prior to the next feeding in order to let gas out. Before patient recruitment, nurse training was provided and parent consent was requested.

Two groups were conformed using a list of random numbers. To avoid nausea or vomiting due to OG tube placement during feeding and to exclude it as a confounder variable, OG tube was placed 30 minutes before feeding. If oxygen saturation decreased to < 85% during tube placement, free-flow oxygen was supplemented until saturation was 90-95%. In case of bradycardia, OG tube was retired and the procedure was postponed until patient recovery. The OG tube technique and feeding plan was specified in the medical orders sheet. Feeding plan was established according to the institution clinical guidelines, which states that patients < 1800 g start at 12.5 ml/kg/day with human milk or preterm formula milk, with small increases of 12.5 ml/kg/day until full feeds (150 ml/kg/day) are reached [22]. Reflux and regurgitation were quantified at the same four moments of evaluation as abdominal distension, by measuring the distance in centimetres from the mouth to the level the milk reached in the OG tube by passing retrogradely tube and the volume in ml expulsed from the mouth, respectively. The use of prokinetics was registered as dichotomous variable at the four moments of evaluation previously mentioned and the characteristics of stool and tube drainage (if present) as well as type of milk were described and registered.

2.1 Statistical analysis

Comparison of qualitative variables was performed with SPSS program 22 version; using Chi-Square, Student’s t and Mann-Whitney’s U for quantitative variables.

3 Results

During the study period, 136 patients were enrolled and 39 were eliminated due to orotracheal intubation (2) fasting (13), and septic shock (24). Ninety-seven patients were included and randomized, 46 in the cenit group and 51 for the 2 x 1 technique. There was no difference between groups in gestational age, weight, sex and NIV type (Table 1). The same type of ventilation was maintained through the study period. With regard to outcome variables, the majority of patients did not present abdominal distension at 4 evaluation moments and type of ventilation only yielded difference in oxygen saturation at 150 ml/kg/day of feeding volume, which was lower in the 2 x 1 technique group with statistically significant difference, p = 0.01 (Table 2). However, other factors that contribute to oxygen saturation were not registered, such as coexisting pulmonary pathology and NIV parameters. The average days to reach 150 ml/kg/day of feeding volume was 17.5 for the cenit group and 13.5 for the 2 x 1 group (p = 0.095). During the study period, the use of prokinetic was null in both groups. There was no difference between both groups regarding the tube drainage, most frequently registered as semidigested when present. The stool pattern was normal in both groups. During the study period 4 patients died. Causes of death were pulmonary haemorrhage (2) and septic shock (2).

Table 1
Demographic and ventilatory characteristics of study population. * x2 ** t Student NIV: Noninvasive ventilation CPAP: Continuous positive airway pressure NV: Nasal ventilation NFV: Nasopharyngeal ventilation. SiPAP: Infant flow (Variable flow) CPAP. HFNC: High Flow Nasal Cannula. SD: Standard deviation. WOG: Weeks of age

Technique Cenit 2X1 p Statistical test

Variable n = 46 n = 51

Gestational age (WOG ± SD) 28.3 (±1.27) 28.7 (± 1.57) 0.19 t

Weight (grams ± SD) 950.8 (± 173.2) 917.3 (±190.8) 0.37 t

Gender

Male 22 32 0.15 χ ²

Female 24 19

Type of NIV

CPAP 30 31 0.85 χ

NV 11 11

NFV 3 7

Sipap 1 1

HFNC 1 1

Technique	Cenit	2X1	p	Statistical test
Gestational age (WOG ± SD)	28.3 (±1.27)	28.7 (± 1.57)	0.19	t
Weight (grams ± SD)	950.8 (± 173.2)	917.3 (±190.8)	0.37	t
Gender
Male	22	32	0.15	χ ²
Female	24	19
Type of NIV
CPAP	30	31	0.85	χ
NV	11	11
NFV	3	7
Sipap	1	1
HFNC	1	1

Table 2

Clinical outcomes of both groups at 4 evaluation moments. * x2 ** t Student NV: Nasal ventilation NFV: Nasopharyngeal ventilation. CPAP: Continuous positive airway pressure SiPAP***: Infant flow (variable flow) CPAP. HFNC: High flow nasal cannula. SD: Standard deviation. WOG: Weeks of age. AD: Abdominal distension

	Feeding start			50 ml/kg/d			100 ml/kg/day			150 ml/kg/d
	CENIT	2X1	P	Cenit	2X1	P	Cenit	2X1	P	Cenit	2X1	P
	N = 46	N = 51	N = 45	N = 49	N = 45	N = 48	N = 45	N = 48
*AD >2 cm
Yes	1	0	0.4	1	0	0.4	3	1	0.3	2	2	1
No	45	51		44	49		42	47		43	46
**Reflux (cm)	0.34	0.46	0.63	0.62	0.66		0.58	0.52		0.62	0.31	0.2
(SD)	(±0.90)	(±1.57)		(±1.67)	(±1.47)		(±1.67)	(±1.50)		(±1.71)	(±0.88)
**Regurgitation (ml)	0.3	0.1	0.14	0.25	0.41		0.03	0.28		0.38	0.42	0.9
SD	(±0.91)	(±0.51)		(±0.87)	(±1.10)		(±0.23)	(±0.91)		(±1.60)	(±1.32)
*Drainge (n)
Bilious	0	1	0.56	0	0	0.6	0	0	0.4	0	0	0.3
Blood	0	0		0	0		0	0		0	0
Semidigested	14	13		12	16		8	12		11	16
None	32	37		33	33		37	36		34	32
Oxygen saturation (%)	85.8	86.3	0.75	85.7	86.8	0.5	86.2	82.6	0.07	86.2	81.5	0.01
(SD)	(±8.6)	(±9.3)		(±9.47)	(±9.78)		(±7.8)	(±11.2)
Type of ventilation (n)
NV	11	11	0.85	15	14	0.95	15	14	0.95	12	17
NPV	3	7		4	6		4	6		2	5
CPAP	30	31		20	21		20	21		22	15
SiPAP	1	1		2	2		2	2		1	1
HFNC	1	1		4	6		4	6		8	9	0.48

*χ² **t Student. NV: Nasal ventilation, CPAP: Continuous positive airway pressure, NPV: Nasopharingeal ventilation, SiPAP: Variable flow CPAP, HFNC: High flow nasal cannula, SD: Standard deviation, cm: centimeters.

Fig. 1

Cenit and 2x1 technique. Two types of OG tube utilization for the management of NIV related abdominal distension in preterm infants. A) Cenit technique: OG tube remains open and lifted permanently. B) 2x1 technique: OG tube remains aside, closed for 2 hours after feeding and opened for 1 hour prior to the next feeding.

4 Discussion

In this study, we did not find a statistically significant difference in demographic variables between groups. There was no difference between groups in respect of the type of NIV. With regard to variables related to feeding tolerance, there was no statistically significant difference in abdominal distension, reflux or regurgitation. Of note, patients in the cenit group showed higher oxygen saturations after feedings at a 150 ml/kg/day volume (p = 0.01). However, other factors that influence oxygen saturation such as ventilation parameters and pulmonary pathology were not included in this study.

One limitation of this study is that abdominal circumference is influenced by several factors such as resistance of the anterior abdominal wall, timing of feeding and defecation, phase of breathing, amount of fat and supine of prone position [23, 24].

In 2012, Dawson et al. from Cochrane neonatal group performed a search in the literature of studies comparing bolus versus gravity feeding in preterm infants < 1500 g with OG tube and the only study found was a randomized clinical trial by Symon et al., which included 31 patients of 24 to 32 weeks of gestation (average of 31.3weeks) and average weight of 1240 g in the bolus group and 1216 g in the gravity group. The variables evaluated in this study were respiratory and heart rate, finding no difference between groups. Clinical variables such as abdominal distension, regurgitation and desaturation were not included. Moreover, the bolus technique described in the study is not comparable to cenit technique [25, 26].

5 Conclusion

The results of this study demonstrate that the use of cenit or 2 x 1 technique does not reduce the presence of abdominal distension or improves feeding tolerance during NIV.

Funding statement This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.

6 Competing interests statement

Authors declare no competing interests.

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