Reliability of an instrument to assess the readiness of preterm infants for oral feeding

Abstracts

TEMA: a transição da alimentação gástrica para via oral do bebê pré-termo é uma das maiores preocupações da equipe de saúde que assiste a esta população e necessita de um critério objetivo que auxilie o início desta transição. OBJETIVO: testar a confiabilidade de um instrumento de avaliação da prontidão do bebê prematuro em iniciar a transição da alimentação gástrica para via oral. MÉTODO: o instrumento é constituído dos seguintes itens: idade corrigida; estado de consciência; postura e tônus global; postura dos lábios e língua; reflexo de procura, sucção, mordida e vômito; movimentação e canolamento de língua; movimentação de mandíbula; força de sucção; sucções por pausa; manutenção do ritmo de sucção por pausa; manutenção do estado alerta e sinais de estresse. O estudo foi realizado na Unidade de Cuidados Intermediários do Hospital de Clínicas da Faculdade de Medicina de Ribeirão Preto - Universidade de São Paulo e a amostra foi constituída de 30 bebês pré-termo que atenderam aos seguintes critérios de inclusão: idade gestacional corrigida menor ou igual a 36 semanas e 6 dias; clinicamente estáveis; ausência de deformidades faciais, distúrbios respiratórios, cardiovasculares, gastrointestinais e neurológicos ou síndromes que impedem ou dificultam a alimentação oral; e não terem recebido alimentação láctea por via oral. A confiabilidade foi determinada através aplicação do teste Kappa para verificar a concordância entre avaliadores. RESULTADOS: os itens cujos valores atingiram concordância excelente foram: estado comportamental, postura e tônus global, postura de lábios e língua, reflexo de vômito e manutenção do estado alerta; os itens que atingiram concordância satisfatória: reflexo de procura, sucção e mordida, movimentação da mandíbula, força de sucção e sucção por pausa; apenas os itens canolamento de língua, manutenção da sucção por pausa e sinais de estresse atingiram concordância insatisfatória. CONCLUSÃO: de forma geral, os itens do instrumento apresentam confiabilidade adequada entre os observadores.

Prematuro; Conduta na Alimentação; Confiabilidade

RESEARCH ARTICLES

Reliability of an instrument to assess the readiness of preterm infants for oral feeding^*

Cristina Ide Fujinaga^I; Nelma Ellen Zamberlan^II; Milena Domingos de Oliveira Rodarte^II; Carmen Gracinda Silvan Scochi^III

^IFonoaudióloga. Doutora em Enfermagem em Saúde Pública. Professora Adjunta I da Universidade Estadual do Centro-Oeste (PR)

^IIFonoaudióloga. Doutoranda em Enfermagem em Saúde Pública - Escola de Enfermagem de Ribeirão Preto da Universidade de São Paulo

^IIIEnfermeira. Doutora em Enfermagem. Professora Titular da Escola de Enfermagem de Ribeirão Preto da Universidade de São Paulo

Endereço para correspondência

ABSTRACT

BACKGROND: the transition from gastric to oral feeding of preterm infants is one of the greatest concerns of health professionals and therefore needs an objective criterion to support the beginning of this process.

AIM: to test the reliability of an instrument that assesses the readiness of preterm infants for the transition from gastric to oral feeding.

METHOD: the instrument is composed by the following items: corrected gestational age; behavioral state; global posture and tonus; lips and tongue posture; rooting, suck, bite and gag reflexes; tongue and jaw movements; tongue cupping; sucking strain; sucking and pause; maintenance sucking/pause; maintenance alert state and stress signs. The study was conducted at the Intermediate Care Unit of the Hospital de Clínicas da Faculdade de Medicina de Ribeirão Preto - University of São Paulo. The research sample consisted of 30 preterm infants who attended the following inclusion criteria: corrected gestational age <36 weeks and 6 days; clinically stable; absence of facial deformities; respiratory, cardiovascular, gastrointestinal and neurological disorders or syndromes that prevent or make oral feeding difficult; and not having received oral feeding of milk. The Kappa Test was used to verify interjudge reliability.

RESULTS: the items that presented high reliability levels were: behavioral state, global posture and tonus, lips and tongue posture, gag reflex and maintenance of alert state. The items that presented satisfactory reliability levels were: rooting reflex, sucking and biting and jaw movement, sucking strain and sucking and pause. Only the items of tongue cupping, maintenance of sucking/pause and stress signs presented unsatisfactory reliability levels.

CONCLUSION: in general, the items investigated by the assessment instrument presented adequate interjudge reliability.

Key Words: Premature Infant; Feeding Behavior, Reliability.

Introduction

Neonatal Care has been transforming in recent year, mainly with respect to care humanization. The concern is to focus care not only on preterm infants' survival, but also to a comprehensive, humanized and preventive care, within an individualized and developmental care perspective (Byers, 2003), with a view to these children's quality of life (Scochi et al., 2003; Nascimento e Issler, 2004). This care reveals a tendency to offer mother's milk as early as possible, so as to meet infants' nutritional needs (Nascimento and Issler, 2003), to encourage breastfeeding (Rocha, Martinez and Jorge, 2002), to improve mother-baby relations (Delgado and Halpern, 2005) and to include the mother in care during the stay at the Neonatal Unit (Fonseca et al., 2004;), besides providing for the adequate development of oral functions (Byers, 2003, Sanches, 2004; Delgado and Halpern, 2005). Despite all of these benefits, there is a need to train the Neonatal Care team in terms of breastfeeding-related issues (Serra and Scochi, 2004).

In clinical practice, professionals face difficulties to precisely determine the ideal moment to start the transition from gastric to oral feeding. In general, the criteria to start this transition are weight and gestational age. In this process, most health professionals have only looked at isolated data for the infants, without an assessment that takes into account aspects of their general conditions, neuro-psychomotor development and oral-motor ability (Thoyre, 2003).

Moreover, at many neonatal units, pacifiers or bottles are used in this feeding transition (Howard et al., 2003; Lau, Smith and Schanler, 2003), as opposed to the benefits of breastfeeding over artificial feeding, due to the clinical risks infants using pacifiers or bottles are submitted to (Sanches, 2004; Andrade and Guedes, 2005).

The assessment of nonnutritive sucking can be used as one sign of maturity for the transition to oral feeding, together with other aspects of the infant's global behavior, such as gestational age, posture and global tonus and behavioral state (Pinelli, Symington and Ciliska, 2002; Caetano, Fujinaga and Scochi, 2003; Thoyre, 2003; Neiva and Leone, 2006).

Most scales assess preterm feeding through descriptive observation, using the Neonatal Oral-Motor Assessment Scale (NOMAS). This scale consists of 13 characteristics of jaw movement and 13 characteristics of tongue movement, which are divided into categories of normal, disorganized and dysfunctional. The assessment of nonnutritive sucking takes 2 minutes and nutritive sucking 5 minutes (Palmer, 1993). An observation scale of premature infants' feeding pattern was developed to verify tolerance to oral milk intake, specifically looking at feeding-related abilities, such as oral-motor organization; coordination between the sucking, swallowing and breathing functions and clinical stability (Thoyre, Shaker and Pridham, 2005). However, Brazilian literature does not offer any protocols to assess premature infants' sucking which have been validated. This is a necessary aspect for a legitimate instrument.

An instrument to assess preterm infants' readiness for oral feeding and the respective instructional guide, including operational definitions for the items to be assessed, were developed and submitted to content and face validation by 15 examiners, with an agreement level of 85% of higher. This instruments contains the following items: corrected age, behavioral organization (behavioral state, global posture and tonus), oral posture (lips and tongue), oral reflexes (rooting, sucking, biting and gag) and nonnutritive sucking (tongue movement, tongue cupping, jaw movement, sucking strain, sucking and pause, maintenance of rhythm of sucking and pause, maintenance of state of alertness and stress signs) (Fujinaga, 2002).

As a part of the clinical validation of this instrument, this study aims to test its interrater reliability.

Method

The study was carried out at the Intermediary Care Unit of the University of São Paulo at Ribeirão Preto Medical School Hospital das Clínicas and approved by the institution's Research Ethics Committee (process No 6225/2003). The infants' mothers signed the Free and Informed Consent Term.

We tested the instrument's reliability by analyzing the level of agreement between the results attributed by two observers to one and the same infant, by means of the Kappa coefficient, which measures interrater agreement and corrects casual proportion. For qualitative analysis, Kappa values above 0.75 were considered as excellent agreement; between 0.40 and 0.75 as satisfactory and below 0.40 as unsatisfactory agreement (Fleiss, 1981). We considered p?0.01 as significant. Two trained oral therapists with experience in neonatology applied the instrument.

A pilot study of 10 infants allowed us to identify problems in operational definitions and the way of observance of infants' behavior. We changed some scale items for better understanding and clarity of operational definitions and observations of infants' behavior (Fujinaga, 2005). The changes were made in item descriptions (Attachment). This article does not include the results of the pilot study.

The sample consisted of 30 preterm infants born between March 2004 and April 2005, who attended to the following inclusion criteria were: corrected gestational age ? 36 weeks and 6 days; clinically; absence of facial deformities; respiratory, cardiovascular, gastrointestinal and neurological disorders or syndromes that impede or difficult oral feeding; and not having received oral feeding of milk. Gestational age was calculated by the medical team through Ballard's somatic assessment (Ballard, Novak and Driver, 1979).

The study subjects were 15 male and 15 female premature infants. The mean gestational age at birth was 32 weeks and 2 days and the mean corrected age 34 weeks and 2 days. Mean weight was 1470 grams and respiratory discomfort at birth was the clinical problem in 75% of cases. Table 1 presents data for the infants in this study.

To apply the scale, two oral therapists assessed each infant 15 minutes before their feeding time. The order of assessment alternated between the two therapists. Although the assessment occurred simultaneously in each baby, the observers had no verbal contact.

Inside the incubator, the infant was assessed in a flexed lateral decubitus position of the lower and upper limbs and aligned head. The first observer stimulated the infant to wake up, using auditory, visual and tactile stimuli. This observer manipulated the infant to verify behavioral organization, oral posture and presence of oral rooting and vomiting reflexes. Both examiners simultaneously observed these behaviors.

The biting and sucking reflexes and nonnutritive sucking were assessed twice, once by each examiner, by means of the gloved little finger. Nonnutritive sucking was evaluated during 1 minute.

Results

Table 2 shows the Kappa (K) results for each item and the qualitative assessment of the agreement results.

Seven (41.2%) items revealed excellent agreement, 7 (41.2%) satisfactory and only 3 (17.6%) unsatisfactory agreement.

Discussion

We did not find any research using a standardized protocol to determine readiness for transition to oral feeding, nor how this transition occurs (Caetano, Fujinaga and Scochi, 2003). There is a need for prospective studies to describe behaviors and physiological variables of preterm infants' ability to initiate and continue oral feeding (Thoyre, 2003).

The instrument described here can be used to evaluate preterm infants' readiness for oral feeding, as interrater reliability scores for most items were good, with a general Kappa agreement coefficient > 0.48. Exceptions were tongue cupping, maintenance of the rhythm of sucking per pause and stress signs.

Tongue cupping is the elevation of tongue sides and the presence of a groove in the central region (Fujinaga, 2005) and is related to feeding efficiency. The low level of inter-observer agreement may be due to measuring difficulties, as it depends on tactile sensitivity and is thus rather subjective.

Direct observation of infants' oral behavior is frequently used for evaluating sucking performance (Nyqvist et al., 2001), but the reliability of clinical observation has to be tested in comparison with objective exams, such as ultrasound imaging and electromyography.

Tongue elevation and sounds have been observed during nonnutritive sucking (Bulock, Woolridga and Baum, 1990), and tongue and hyoid bone movements during nutritive sucking, using bottles, and during nonnutritive sucking using pacifiers (Miller and Kang, 2007) by means of ultrasound imaging. However, the cupping movement has not been mentioned during sucking. Inside the uterus, the cupping movement has been observed during amniotic fluid sucking of healthy fetuses with average gestational age of 24 weeks and 3 days. Images were videotaped and analyzed by two observers, with Pearson's R=0.82 (Miller, Sonies and Macedônia, 2003).

We highlight the need for other studies to test the agreement between clinical observation and an objective method for verifying tongue cupping.

Another item that is hard to measure is the maintenance of the rhythm of sucking and pause. This has already been mentioned in other interrater reliability studies of sucking behavior at the mother's breast (Nyqvist et al., 1996). Filming the infant's behavior or surface electromyography is considered as the most objective way of measuring this item (Nyqvist et al., 1991).

These records allow two or more observers to check sucking behavior monitored minute per minute. Surface electromyography verifies muscle activity at the time of sucking (Nyqvist et al., 2001). In this case, the clinical observation of the infants' behavior also needs to be validated through an objective exam.

Scores for the presence of stress signs were also unsatisfactory. This result is probably due to changes in the infant's clinical stability, caused by the child's manipulation during the assessment. For future studies, we suggest infant monitoring to obtain objective parameters, although it is not known yet what exact parameters can be expected during oral feeding (Thoyre, 2003).

Conclusion

In general, the scale items presented adequate reliability interrater reliability. There is no sufficient evidence yet to permanently exclude those items with unsatisfactory reliability, that is, tongue cupping, maintenance of rhythm of sucking and pause and stress signs. We recommend other reliability studies, based on the use of this scale, by other health professionals active in premature care at neonatal units, or comparing the results of this instrument with objective methods.

The next study phase is the application of the scale in clinical practice to establish sensitivity and specificity levels and predictive values.

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*

Trabalho Realizado na Unidade de Cuidados Intermediários do Hospital de Clínicas da Faculdade de Medicina de Ribeirão Preto - Universidade de São Paulo.

Publication Dates

• Publication in this collection
  16 Sept 2008
• Date of issue
  June 2007

History

• Accepted
  17 May 2007
• Reviewed
  15 May 2007
• Received
  07 Feb 2007