This randomized controlled study was conducted in the neonatal unit of a tertiary care centre over 3 months from March-May 2014, following approval from our institutional ethics committee. All infants admitted to the unit and born between 28 to 32 weeks gestational age, once medically stable with no respiratory support for atleast 48 hours and on full gavage feeds of 150cc/kg/day, were eligible for enrollment into the study. Infants having respiratory distress and those with chronic medical complications like BPD, IVH, PVL, NEC, chromosomal anomalies or craniofacial malformation were excluded from the study. Written informed consent was taken prior to enrollment.

Infants meeting eligibility criteria were randomized to receive oro-motor stimulation using either Premature Infant Oro-Motor Intervention (PIOMI) or sham intervention. Randomization was done using a computer generated randomization sequence placed in sealed, opaque, sequentially numbered envelopes. The physician on call opened the sequentially numbered sealed opaque envelopes and randomized infants to the respective groups. The principal investigator underwent a training for this oro-motor intervention in the department of occupational therapy for 15 days prior to the start of the study regarding correct order of steps in the protocol with correct technique and time spent at each step. Intervention in both the groups was done by the principal investigator and duration did not exceed 5 minutes in either group.

Infants randomized to PIOMI group were subjected to 5 minutes of PIOMI intervention three times daily for 7 consecutive days using all aseptic precautions with gloved fingers. The PIOMI is a 5-minute oral motor intervention that provides assisted movement to activate muscle contraction and provides movement against resistance to build strength [5]. Sham intervention consisted of unstructured stroking procedure done in and around the oral cavity of the infants.

Baseline oromotor evaluation was done in both the groups by a trained occupational therapist who had considerable experience of working in the neonatal unit and handling preterm babies. This occupational therapist was blinded to the group allocation and evaluation was done with a scale known as Neonatal Oro motor Assessment Scale (NOMAS) [6]. Maximum total score in NOMAS is 48 and higher score in NOMAS indicated better oro motor skills [7]. A repeat evaluation was again done by the same therapist after 7 days of intervention to eliminate inter-observer bias.

Primary outcome of the study was the improvement in the NOMAS score after 7 days of intervention. Secondary outcomes included transition time to reach full independent wati spoon feeds, duration of hospital stay and weight gain after intervention.

Study done by Fucile, et al. [8] had shown improvement in oro-motor skills with pre-feeding intervention. A sample size of 32 babies with 16 in each group was based on detecting a difference of 5 in NOMAS score between the PIOMI and the SHAM intervention group using a two sided alpha error of 0.05, beta error of 0.2 (power 80%) and a standard deviation of 5.

Statistical analysis: Baseline characteristics and outcome measures on continuous scales were analyzed by using two sample t test. Statistical analysis was performed by applying intention to treat principle and P<0.05 was considered statistically significant.

A total of 76 preterm infants less than 32 weeks were admitted in the unit during the 3 month study period out of which 42 were assessed for inclusion. Out of them, 30 were included in the study with 16 in PIOMI group and 14 in the sham intervention group (Fig. 1). The baseline demographic characterstics of the enrolled infants were similar (Table I).

Fig. 1 Flow of participants in the study.

TABLE I	Baseline Characteristics of Infants in Two Study Groups

Improvement in mean (SD) NOMAS score over 7 days from baseline was also highly significant in the study group infants as compared to control group [9.25 (1.73) vs 4.79 (1.52), P<0.001). Infants in the study group reached full wati spoon feeds significantly earlier than the infants in control group. There was a statistically significant increase in weight gain after enrolment in infants in study group than infants in control group. However, there was no significant difference in terms of hospital stay after enrolment, age at discharge, weight gain after enrolment and weight at discharge (Table II).

TABLE II  Study Outcomes in the Two Groups

This randomized control trial showed that pre-feeding intervention with PIOMI is effective in improving the oro-motor function of the preterm infants.

The major limitation of our study was it being a single center study with a small sample size. We have evaluated PIOMI intervention based on NOMAS score instead of feeding efficacy assessment based on volume and rate of total milk intake at each feed and time to start sucking from breast. Due to infrastructure constraints, infants in our study were discharged once they were on full wati spoon feeds and thus, the effect of intervention on attaining full breast feeds could not be seen.

Gaebler and Hanzlik [9] had demonstrated that infants receiving a peri- and intra-oral stimulation just before oral feedings scored better on the NOMAS which was also confirmed in our study. Another study demonstrated that the PIOMI was well tolerated by 29-week PMA infants [5]. We have not seen any unfavorable response in preterm infants who received the thrice-daily PIOMI intervention for 5 minutes. It is necessary to limit any form of intervention to a five minute time frame in preterm infants to reduce the likelihood of the infant experiencing negative physiological and behavioral effects due to a prolonged duration of stimulation.

We found early transition from tube to full independent oral feeds which was also reported in earlier studies [8,10]. A recent study by Bala, et al. [11] had also shown that oromotor stimulation decreases the duration of gavage feeding. There was a significant increase in weight-gain per day after enrolment in infants in PIOMI group than infants in sham intervention group. An enhanced sucking rate with stroking of the cheeks and increase in volume intake during an oral feeding session has also been earlier reported [12,13]. Infants in our study group had a shorter hospital stay as compared to control group, but the difference was not statistically significant.

In conclusion, our study supports the hypothesis that 5-minute PIOMI three times daily for seven days for preterm infants between 28 to 32 weeks of gestational age significantly improves their oro-motor skills. It was effective in reducing transition time from gavage to oral feeds and infants had increased weight gain with shorter duration of hospital stay. Larger randomized controlled trials with a longer follow-up are needed to confirm the benefits seen in our study, and to further evaluate the effect on time to hospital discharge as a primary outcome.

Contributors: KA,HP,JM: conceived and designed the study; KA,NK,SM: were involved in patient care; KA,SG,HP: collected the data; KA,SG,HP: analysis and interpretation of data; KA,SG: drafting the manuscript; All authors approved the final version of manuscript.

Funding: None; Competing interests: None stated.