Open Journal Systems

ORIGINAL CONTRIBUTIONS

Received: February 19^th 2015

Judged: February 17^th 2016

Validation of a clinical nutritional sucking scale

Mario Enrique Rendón-Macías,^a Miguel Ángel Villasís-Keever,^a María del Carmen Martínez-García^a

^aUnidad de Investigación Médica en Epidemiología Clínica, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Ciudad de México, México

Communication with: Mario Enrique Rendón-Macías

Telephone: (55) 5627 6900, extension 22497

Email: drmariorendon@gmail.com; mario.rendon@imss.gob.mx

Objective: Suck dysfunction in breastfeeding infants has an impact on their appropriate nutrition. The objective was to build and validate one clinical nutritional sucking scale in the components of sucking, swallowing, and respiration.

Methods: The scale was carried out in two phases: face-validity and psychometric validity. The first was done by expert consensus. For the second phase, 179 infants (153 healthy newborn and 26 infant less than 6 month of age) and 86 infants with high risk for abnormal sucking were evaluated with the new scale. Three observers evaluated all patients during their feeding. With an initial scale of 10 items we calculated the inter-observer concordance and the internal consistence. With an analysis of the mail components and a discrimination index we reduced to pertinent items. Each component of the scale was compared with clinical variables.

Results: We reached a 7 items scale, which showed high reliability (Cronbach’s alpha of 0.77 and inter-observer concordance of 0.98. The suck component correlated positively with the ingested volume (Ro = 0.61), the swallow component with the peripheral oxygen saturation (Ro = 0.24), and the breath component with the respiratory frequency (Ro = 0.50). With this scale, we can establish different patterns of sucking abnormalities related with history of neurological abnormalities, hemodynamic alteration and immaturity.

Conclusions: In this study the clinical nutritional scale showed to be reliable and valid for its use in sucking problems classification. More studies are required to evaluate its application for oral stimulation therapies.

Key words: Breast feeding; Scales; Nutrition processes; Nutrition assessment

---

The process by which an infant gets its food is called nutritional suction.^1,2 This process consists of three related components: expression / suction,^2,3 swallowing, and respiration (E/S-S-R).^4,5 The infant’s expression / suction generates extraction pressure for the fluid contained in an external reservoir to enter the oral cavity. Once the bolus is formed there, the liquid is directed to the digestive tract, in a process called swallowing, bypassing the respiratory pathways.^6,7 Both processes must be coordinated with breathing in its different phases.^4,8

The effectiveness of suction depends on proper integration and synchronization of the structures of the lips, cheeks, tongue, and palate, in bolus formation and propulsion towards the back of the oral cavity for swallowing.² In healthy term infants, this process needs to be rhythmic and coordinated with continuous respiration (aerobic phenomenon), to assure an adequate intake of food that meets their metabolic demands with the least energy expenditure and protects their airways from contact with food.^5,9 In the normal process of the nutritive sucking sequence, E/S-S-R is 1: 1: 1, but in healthy children around six weeks of life the process can take on a sequence of 2 or 3: 1: 1. These changes have been explained by a process of encephalization, with greater volitional control of nutritive suction.¹⁰

Disorders in the E/S-S-R process can be divided into two groups: those associated with the lack of coordination of each of the structures due to immaturity, and those associated with specific anatomical disorders with and without functional neurological damage.⁵ The former have been defined as disorders of disorganization and the latter as suction dysfunction,^11,12 although they are not mutually exclusive.

Symptoms associated with E/S-S-R dysfunction can be divided into four groups according to the most altered component: during E / S one can observe non-starting of suction, trouble holding the nipple, poor lip seal formation, liquid escaping the corners of the mouth, excessive tongue protrusion, and lack of integration of repeated suctions in clusters.² During swallowing one can observe signs of choking such as retching, nausea and vomiting, cough, nasal regurgitation of milk, and laryngeal noise.⁵ Throughout the process breathing may fluctuate in frequency, and periods of apnea, cyanosis, and cardiac rhythm disorders may appear.¹³ In addition to these clinical signs there are some behavioral responses that have been associated with children’s defense mechanisms to preserve their integrity during suction, for example, spitting out the nipple, turning their head, crying, biting the nipple, stopping suction, or fatigue and distraction with prolonged pauses.² When all of these signs are present, uncoordinated movements are happening in the different buco-pharyngeal-esophageal structures, although the specific processes are unkown.¹⁴

In addition to the previous signs, abnormal suction impacts the efficiency of feeding, expressed as little volume obtained by suction, prolonged feeding time, and in the end low intake of the liquid offered.^2,12

Faced with the possibility of taking preventive or management action in infants with abnormal suction,^8,15 different diagnostic clinical scales have been designed and evaluated. Many have been aimed at improving breastfeeding, and have been evaluated by the mothers themselves as well as by health personnel;^12,16 others have been more generally about the suction process.¹¹ The most accepted in the latter group is the Neonatal Oral-Motor Assessment Scale) (NOMAS).¹⁶ This scale has been used to classify infants with suction-swallowing as dysfunctional or disorganized, based on the characteristics of jaw and tongue mobility. The evaluation by this scale requires training the observer, who once trained reports concordance rates of 59 to 100% according to each item,¹¹ although revised and modified scales have been used for high-risk children. Some authors have considered this the gold standard in diagnosing suction-swallowing problems; however, as a clinical scale it cannot determine altered intraoral processes and it does not consider clinical data. 

This study aimed to construct and evaluate a new diagnostic clinical scale that met the following four criteria: 1) exploring the three areas of suction (expression / suction-swallowing-breathing), 2) considering these areas according to their components of clinical expression, 3) showing high enough internal and inter-observer consistency to be applied by untrained personnel, and 4) distinguishing suction characteristics in high-risk infants to assess their treatment.

Methods

With the consensus of five experts in gastroenterology, neonatology, physical medicine, neurology, and pediatrics, the components of suction were analyzed. The rating scale was constructed considering the three phases of suction-swallowing-breathing, for each and according to the data reported in the literature the most common signs related to incoordination of these phases were sought. At the beginning a total of 24 potential clinical data were issued, of which a reduction to 10 was made with 80% or greater agreement among the participants. The number was selected to create a simple scale. For each item four levels of impairment in nutritive sucking were issued. The score of 4 was considered the ideal condition and 1 was a major disorder. The scale items were ordered following the expected sequence for normal suction.

The study was conducted at the Hospital Rural Oportunidades No. 43 of the Instituto Mexicano del Seguro Social of Huautla de Jimenez, Oaxaca, and the Unidad Médica de Alta Especialidad, Hospital de Pediatría del Centro Médico Nacional Siglo XXI in Mexico City.

To assess whether the scale incorporated the three components of the process of nutritive suction, four neonatologists and three physiatrists different from the initial group were asked for feedback on the content of the proposed scale and its possible relationship with the relevant clinical aspects that should be evaluated during suction. Each doctor issued their opinions; according to the comments, they concluded that the scale evaluated the main components of suction, and although they accepted the 10 items of the scale as the most suitable, there were proposals to add some other symptoms. Because the objective was to assess the relevance of the items on the scale and change only those that could be exchanged and thus not increase their number, it was decided to leave the proposal as is (Figure 1).

To validate the scale, it was applied to infants under three months of age or equivalent gestational age, corrected in case of prematurity. Infants were selected according to their risk of presenting suction disorders, as follows:

• Low-risk infants (normal or controls = C): This group consisted of 153 newborns who were healthy children without malformations at 24 or 36 hours of life in a physiological nursery. All were fed by suction (breastfeeding or formula) with at least four previous feedings without the presence of vomiting. Because the risk group had infants over three days of life, 26 age-matched normal infants were studied.
• High-risk infants (HR): The group consisted of 86 patients under three months of age or equivalent age, corrected in case of prematurity. All had some pathology meriting admission to the high specialty surgical-medical unit. By their medical history and nutritional conditions these patients would be expected to have abnormal nutritive suction. At the time of evaluation they had to be partially or fully fed enterally with attempts at suction. All patients’ neurological conditions were determined by specialists in the area. 

This study did not include infants with malformations of the oral cavity (cleft lip or palate).

The evaluation was conducted during morning shifts, after at least two hours of fasting. The formula or milk offered and the amounts were provided according to the indication of the physicians responsible for each patient. For purposes of the study only the first 15 minutes of feeding were evaluated, or sooner if feeding was complete. Feeding was done by the mother or the nurse responsible for the minor. Each child was evaluated at one feeding. For the high-risk group sensors were placed to monitor heart rate, breathing, and oxygen saturation. If oxygen support was required, this remained in place. If there was a frequency higher than 120 x minute or less than 90 x minute, respiratory rate greater than 60 x min, apnea > 2 minutes, saturation < 90%, or signs of choking, the procedure was suspended.

Evaluations were conducted by three medical specialists in physical therapy and rehabilitation, who were unaware of the infants’ diagnoses. The three doctors knew the scale and criteria for scoring and conducted the evaluation independently.

The work was approved by the Research and Ethics Committee of the Hospital with registration number R-2007-3603-39. Informed consent was requested of children’s parents. All infants at high risk received oral stimulation therapy.¹⁵ Low-risk infants received it only if there was any clinical data at the time of the study. All received information on successful breastfeeding.

As for statistical analysis, with variable content validity the response rate for each item and its suitability for analysis were evaluated. Items with low response frequency were excluded (for example, over 95% of subjects had a score of 4 on one item). The homogeneity of the items was evaluated by the item-total scale correlation method to eliminate those with a Pearson correlation < 0.20.¹⁷

In order to assess whether components of the scale included the entire suction process, factor analysis was done by principal components. The Kaiser-Meyer-Olkin Test (KMO) was applied to determine the adequacy of the sample, and Bartlett’s sphericity test for the contrast. The components were obtained by varimax rotation with Kaiser normalization when they had Eigenvalues ​​greater than 1. An item was considered as having a component if it had a score higher than 0.50. Each item was assessed according to its power to discriminate between subjects with high and low scores. The analysis was performed considering the following formula:

Where Ui is the number of people above the median who had a positive score (4) in item i; Li is the number of people below the median with a positive score in item i, and ni is the number of people above the median.¹⁷

To assess the internal consistency of the instrument its Cronbach's alpha on the 10-item scale was determined, and its variation when each item was removed. The intra-observer consistency was determined with the intraclass correlation coefficient for the aggregate scale and each item. For the aggregate scale, a percentage ≥ 60 was considered as acceptable agreement.

The correlation was analyzed between the score on the scale and the effectiveness of the suction in volume ingested in five minutes by free suction. For this purpose the volume difference provided by the bottle was determined before and after five minutes of feeding. In the case of breast feeding it was established by weighing pre- and post-nursing. For the respiratory component the scale was correlated with the average respiratory rate maintained by the child during suction and the average saturation. The correlation was for the whole aggregate scale and considering the items grouped into components. The Pearson correlation coefficient was used and the value > 0.50 was considered significant.

To determine the behavior of the scale in relation to the clinical data of patients at high risk (HR), infants were grouped into those with impaired cardiopulmonary stability with or without neurological damage, and infants with a prolonged history of feeding by orogastric probe or prolonged intubation. The first due to an increased risk of dysfunctional suction and second due to possible disruption.

All analyses were performed considering a significance level of alpha less than 0.05. A sample size of at least 45 patients was considered, taking into account that an intraclass correlation coefficient to assess inter-observer consistency in three subjects should be ≥ 0.80, alpha = 0.05, beta = 0.20. Factor analysis was required for at least 150 samples. Statistical analysis was done using SPSS version 19.

Results

With respect to infants studied (HR and C), there were no statistically significant differences with respect to gender (girls in HR = 52.9% versus C = 50.3%, Chi-squared 0.20, p = 0.65); however, the weight was lower in the high-risk group (HR = 2.57 kg [2.1-3.6] versus C = 3.0 kg [2.7-3.4], Student's t p < 0.001). The group of high-risk infants consisted of 21 preterm infants (30.8%) with a history of prolonged intubation and data of bronchopulmonary dysplasia; all of them had initiated oral suction after several days of feeding by gastric tube (an average of 10 +/- 5 days) and had no neurological damage data although with weak responses to sucking reflex. The second group (33.8%) consisted of infants with cardiac and digestive malformations with early surgeries and feeding by orogastric probe, two of them with agenesis of the corpus callosum. The last group, which had 24 infants (35.3%), included infants with data of perinatal asphyxia or infants with hypoxic-ischemic encephalopathy. All patients received oral stimulation therapy after evaluation.

Of the 10 initially selected items, three were eliminated for the later evaluation (Figure 1): 1) milk comes out one or both nostrils: this information was not presented in any patient, and also it was considered that presenting this would indicate suspension of feeding by suction; 2) crying: this data could indicate previous appetite, but was not presented during suction; 3) cyanosis: this only occurred in patients with cardiac and respiratory problems; they were always given supplemental oxygen. Therefore, the later analysis was performed with the seven subsequent items. With these items the factor analysis by principal component was done with the sample of 265 children. The KMO sample adequacy test reported a very appropriate score of 0.80. The significance of the matrix correlation by Bartlett’s test was also significant at p < 0.001. The analysis extracted three main components that accounted for 69.6% of the variance (component 1 = 29.9%; component 2 = 21.8%, and component 3 = 17.8%). Component 1 grouped four items representing clinical data related to the process of suction / expression: Forms lip seal, maintains suction, spits out the nipple, and milk comes out of mouth. The second component was composed of two items related to swallowing: coughs, chokes. And the third component, a single item, was associated with impaired breathing due to pauses from fatigue. Thus, the scale maintained the three processes of nutritive sucking, though not balanced in their items. With this final stage the other assessments (Table I) were performed.

In assessing the aggregate seven-item scale, Cronbach's alpha was 0.77 (95% confidence interval 0.74-0.89). This consistency did not vary significantly with the removal or addition of each item. By varying the individual removal of each item, consistency remained between 0.718 and 769 (Table II). The inter-observer consistency showed a concordance of 0.98 or 98%, which translates to high reproducibility. In evaluating the consistency by item, with the exception of the assessment of coughing during suction, which has good consistency, the others were above 0.90. The discriminative index was adequate in all items above 0.15.

All children completed at least five minutes of feeding and the evaluation was conducted with this time.

The final scale was scored with a maximum score of 28 and a minimum of 7. As observed in the graph, the control group children presented a median score of 25 (minimum 21 and maximum 28), a different score than the children from high-risk Groups 1 and 3, with medians 23 (minimum 17 and maximum 26) and 19 (minimum 3 and maximum 27). In Group 2, although 60% had a score above 25, 40% were below that value. The group with the lowest rating was the infants with a history of neurological damage, which was a statistically significant difference (p < 0.05) compared to other groups.

By analyzing the most affected components of the scale according to medical history (Figure 2), the percentages in the behavior items were different. For the group of infants with a history of prolonged feeding by gastric tube due to surgery at an early age, it was observed that the average scale score was not different from that of the control children, which was attributable to a good score in creating lip seal or maintaining suction movements. However, there were infants who showed low scores for milk coming out of the mouth or gagging with coughing or vomiting; some also responded with pauses during feeding (Figure 2a). 

For the group with cardiopulmonary instability due to prematurity, it was observed that they had low scores on the items forming lip seal and maintaining suction movements, they tended to spit out the nipple and therefore milk often came out during feeding. Signs of choking were observed with low frequency, but it was common to see suction interrupted by pauses (Figure 2b).

In the group of children with a history of neurological damage and cardiopulmonary instability, low scores were found within the three phases of nutritive sucking. Most struggled to form a lip seal on the nipple, had irregular movements during suction, and easily spat and let milk out the mouth; choking and coughing were more frequent than in the other groups, and feeding had constant breaks (Figure 2c).

As for the evaluation of the effectiveness of suction, the items grouped by components were correlated. The items assessing suction (four) showed a positive correlation with the volume of ingested milk (suction Rho = 0.61, p < 0.01) without altering the respiratory rate (Rho = 0.21, p < 0.05) and peripheral oxygen saturation (Rho = 0.12, p < 0.05). For the two items of the swallowing component, the score correlated moderately with peripheral oxygen saturation (R = 0.31, p < 0.01) and with little influence on the volume ingested (Rho = 0.24, p < 0.01) and respiratory rate (Rho = 0.11, p < 0.05). In the case of the ventilation component, which was only assessed by one item, the correlation was with the volume of ingested fluid (Rho = 0.50, p < 0.01) and respiratory rate (Rho = 0.53, p < 0.01), and to a lesser extent saturation (Rho = 0.63, p < 0.01).

Discussion

Evaluating the suction process in the care of infants is critical for making decisions regarding initiating and continuing feeding. The presence of signs associated with incoordination in this process often limited the decision to discharge the child home or not, once some medical problems have been solved. For years, the decision was based on a comprehensive assessment of the infant and the subjective assessment of the doctors who care for these children. That is why more reproducible and validated scales are indispensable to have benchmarks on which to base conclusions. Also, the need to have uniform criteria for improving the suction of children made it necessary to design evaluation strategies.^18,19

This scale was designed with the purpose of being a tool of daily clinical use to allow the assessment of an infant’s conditions of suction and the potential to discriminate changes with applied therapies.

The scale considers the most important signs to be monitored during suction and therefore analyzes two of the phases of coordination that translate the adequacy of suction to ensure adequate volume without incoordination.

Compared with other scales available,¹⁸ with this one we hope for neonatal capabilities to be assessed to properly execute suction-swallowing-breathing during breast or bottle feeding.¹⁶ Other scales have been aimed primarily at the interaction of the mother-child dyad to assess whether the infant has good behavior during suction (International Breastfeeding Assessment Tool)²⁰ or how the mother perceives her ability to feed her child (Bristol Breastfeeding Assessment Tool).¹⁹ These scales allow follow-up of suction in breast-fed infants, but are not very sensitive in the evaluation of important physiological behaviors in hospitalized infants and those who are subjected to oral stimulation therapies.

Other scales have been designed to evaluate the characteristics of the motor components of suction, such as the Neonatal Oral-Motor Assessment Scale (NOMAS)¹¹ and in preterm infants the Early Feeding Scale (EFS),²¹ both must be applied by personnel with special training, in particular the EFS, since it is more complicated, because it involves a checklist of 36 items. Both scales are efficient in motor evaluation, but do not consider the clinical aspects of the newborn; so our scale could be more useful because it is easy to use and requires no prior training, as demonstrated by its high inter-observer agreement. Our scale, like the two previously mentioned, is directly applicable to the neonate and not the mother-child dyad; therefore, you can assess both breast-fed and bottle-fed infants.

Because there is no gold standard scale, we conducted a concurrent validation of our scale with efficiency measures in suction. In this regard we found that infants with high scores were correlated with a good intake of milk. In general, it is accepted that the aim of the suction is to consume sufficient volume for the infant to reach their nutritional requirements while making the lowest output of energy.⁹ Indirectly, we can say that the high scores were in children with adequate intake volumes who maintained breathing and peripheral saturation.

On the other hand, it is essential that during feeding the infant not present signs of choking, fatigue, or severe regurgitation. These data are indicative of a disorder in the suction-swallowing mechanism. Their sporadic presence does usually not modify oral feeding, but their persistence is indicative that this way of feeding should be suspended. Therefore, the scale was designed to consider these signs. In addition, our scale considered another earlier sign of difficulty sucking: spitting out or rejecting the nipple or bottle. This seems to be a defense mechanism to prevent the child from choking or drowning, which happen with fluid retention in the oral cavity. In the suction-swallowing mechanism, the volume transferred from the oral cavity to the oropharynx is an important modulator of suction frequency.²²

Although our scale has shown to have valid points for use in the evaluation of infants with suction problems, its use in therapy studies for oral rehabilitation is still necessary in order to complete its validation. In addition, it is necessary to establish whether the scale is sensitive to detect changes that result in an improvement in the efficiency of suction in a short time, since oral stimulation therapies are directed towards rapid changes given the need to feed the infant this way.

Finally, we recognize that although the scale involves the three processes of suction, it is not balanced in the items considered for each; however, we recognize that the first phase (suction) is essential for the coordination of the later stages and is also the target of many oral stimulation interventions.²³

Conclusion

At the moment we conclude that the clinical scale of nutritive sucking shows attributes of validity for use as a routine tool in assessing suction. The instrument is simple, reproducible, and valid.

Acknowledgments

To Dr. Rosalba Mosco Peralta and her medical team for their support in the evaluation of infants.

Financing

The work was supported by the Consejo Nacional de Ciencia y Tecnología (CONACYT) FIS / IMSS / PROT / 645.

References

1. Gryboski JD. Suck and swallow in the premature infant. Pediatrics. 1969 Jan;43(1):96-102.
2. Lau C, Kusnierczyk I. Quantitative evaluation of infant’s nonnutritive and nutritive sucking. Dysphagia. 2001;16(1):58-67.
3. Bu’Lock F, Woolridge MW, Baum JD. Development of co-ordination of sucking, swallowing and breathing: ultrasound study of term and preterm infants. Dev Med Child Neurol. 1990 Aug;32(8):669-78.
4. Vice FL, Bamford O, Heinz JM, Bosma JF. Correlation of cervical auscultation with physiological recording during suckle-feeding in newborn infants. Dev Med Child Neurol. 1995 Feb;37(2):167-79.
5. Stevenson RD, Allaire JH. The development of normal feeding and swallowing. Pediatr Clin North Am. 1991 Dec;38(6):1439-53.
6. Gewolb IH, Bosma JF, Taciak VL, Vice FL. Abnormal developmental patterns of suck and swallow rhythms during feeding in preterm infants with bronchopulmonary dysplasia. Dev Med Child Neurol. 2001 Jul;43(7):454-9.
7. Gewolb IH, Vice FL, Schwietzer-Kenney EL, Taciak VL, Bosma JF. Developmental patterns of rhythmic suck and swallow in preterm infants. Dev Med Child Neurol. 2001 Jan;43(1):22-7.
8. Mizuno K, Ueda A, Takeuchi T. Effects of different fluids on the relationship between swallowing and breathing during nutritive sucking in neonates. Biol Neonate. 2002 Jan;81(1):45-50.
9. Jain L, Sivieri E, Abbasi S, Bhutani VK. Energetics and mechanics of nutritive sucking in the preterm and term neonate. J Pediatr. 1987 Dec;111(6 Pt 1):894-8.
10. Qureshi MA, Vice FL, Taciak VL, Bosma JF, Gewolb IH. Changes in rhythmic suckle feeding patterns in term infants in the first month of life. Dev Med Child Neurol. 2002 Jan;44(1):34-9.
11. Da Costa SP, van der Schans CP. The reliability of the Neonatal Oral-Motor Assessment Scale. Acta Paediatr Oslo Nor. 1992. 2008 Jan;97(1):21-6.
12. Da Costa SP, van den Engel-Hoek L, Bos AF. Sucking and swallowing in infants and diagnostic tools. J Perinatol Off J Calif Perinat Assoc. 2008 Apr;28(4):247-57.
13. Abadie V, André A, Zaouche A, Thouvenin B, Baujat G, Schmitz J. Early feeding resistance: a possible consequence of neonatal oro-oesophageal dyskinesia. Acta Paediatr Oslo Nor. 1992. 2001 Jul;90(7):738-45.
14. Rendón-Macías M, Meneses-Serrano J. Fisiología de la succión nutricia en recién nacidos y lactantes. Boletín Médico Hosp Infant México. 2011;68(4):319-27.
15. Rendón-Macías ME, Cruz-Perez LA, Mosco-Peralta MR, Saraiba-Russell MM, Levi-Tajfeld S, Morales-López MG. Assessment of sensorial oral stimulation in infants with suck feeding disabilities. Indian J Pediatr. 1999 Jun;66(3):319-29.
16. Tamilia E, Taffoni F, Formica D, Ricci L, Schena E, Keller F, et al. Technological solutions and main indices for the assessment of newborns’ nutritive sucking: a review. Sensors. 2014;14(1):634-58.
17. Streiner DL, Norman GR. Health Measurement Scales [Internet]. Oxford University Press; 2008. Available from: http://www.oxfordscholarship.com/view/10.1093/acprof:oso/9780199231881.001.0001/acprof-9780199231881
18. Howe T-H, Lin K-C, Fu C-P, Su C-T, Hsieh C-L. A Review of Psychometric Properties of Feeding Assessment Tools Used in Neonates. J Obstet Gynecol Neonatal Nurs. 2008 May 27;37(3):338-49.
19. Ingram J, Johnson D, Copeland M, Churchill C, Taylor H. The development of a new breast feeding assessment tool and the relationship with breast feeding self-efficacy. Midwifery. 2015 Jan;31(1):132-7.
20. Matthews MK. Developing an instrument to assess infant breastfeeding behavior in the early neonatal period. Midwifery. 1988 Dec;4(4):154-65.
21. Thoyre SM, Shaker CS, Pridham KF. The early feeding skills assessment for preterm infants. Neonatal Netw NN. 2005 Jun;24(3):7-16.
22. Medoff-Cooper B, Bilker W, Kaplan JM. Sucking patterns and behavioral state in 1- and 2-day-old full-term infants. J Obstet Gynecol Neonatal Nurs JOGNN NAACOG. 2010 Oct;39(5):519-24.
23. Arvedson J, Clark H, Lazarus C, Schooling T, Frymark T. Evidence-based systematic review: effects of oral motor interventions on feeding and swallowing in preterm infants. Am J Speech-Lang Pathol Am Speech-Lang-Hear Assoc. 2010 Nov;19(4):321-40.

Enlaces refback

• No hay ningún enlace refback.