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Print version ISSN 0034-7094
On-line version ISSN 1806-907X
Rev. Bras. Anestesiol. vol.57 no.5 Campinas Sept./Oct. 2007
Evaluación del dolor en neonatología
Yerkes Pereira e SilvaI; Renato Santiago Gomez, TSAII; Thadeu Alves MáximoIII; Ana Cristina Simões e SilvaIV
e Neonatologista do Hospital Life Center, Belo Horizonte, MG
IIProfessor Adjunto do Departamento de Cirurgia da FM/UFMG
IIIAluno de Graduação da FM/UFMG
IVProfessora Adjunta do Departamento de Pediatria da FM/UFMG
BACKGROUND AND OBJECTIVES: The study of pain has seen a great development
in the last decades, making evaluation and intervention a growing concern among
health professionals. The objective of pain evaluation should be to provide
accurate data to determine the actions that should be taken to relieve or abolish
it and, at the same time, to evaluate the efficacy of those actions. The objective
of this review was to discuss the methods used to evaluate pain in neonatology,
since treatment strategies used without systematic pain evaluation are not effective
CONTENTS: A widely accepted, easy to apply and uniform technique to evaluate pain in children, especially newborns and infants, that can be used in all situations does not exist. Before trusting the accuracy of the data, it is necessary that health professionals trust the instruments used to collect the data. Several indicators can be used to evaluate, quantify, and qualify the painful stimulus and, when analyzed as a set, allow the discrimination between pain and non-painful stimuli. Although the objective standardization of measuring pain severity is desirable, it does not exist. Measurement of pain in this age group is done by assessing physiological (heart rate, respiratory rate, blood pressure, and etc.) and behavioral (facial expression, posture, and vocalization or verbalization) parameters using evaluation scales, each one with its advantages and limitations.
CONCLUSIONS: The current concern with better methods to measure and evaluate pain contributed to increase the sensitivity of health professionals regarding the nature of painful experiences. Pain should be valued as the fifth vital sign and evaluated in a systemized manner, including in newborns.
Key Words: EVALUATION: Pain; MEASUREMENT TECHNIQUES: Pain; PAIN: neonatology.
JUSTIFICATIVA Y OBJETIVOS: El estudio del dolor ha avanzado mucho en
las últimas décadas haciendo con que la evaluación y la
intervención sean una preocupación creciente entre los profesionales
de la salud. El objetivo de la evaluación del dolor debe ser el de proporcionar
datos precisos para determinar cuáles acciones deben ser toma de las
para aliviarlo o eliminarlo y la mismo tiempo, evaluar la eficacia de esas acciones.
La finalidad de esta revisión fue discutir los métodos utilizados
en la evaluación del dolor en neonatología, cuando las estrategias
de tratamiento utiliza de las sin una evaluación sistemática del
dolor no son eficaces o adecua de las.
CONTENIDO: No existe ninguna técnica ampliamente aceptada y fácilmente ejecutable y uniforme para la evaluación del dolor en niños, especialmente en los recién nacidos y lactantes que pueda ser utilizada en todas las situaciones. Antes de confiar en la exactitud de los datos de Evaluación, se hace necesario que los profesionales de la salud se sientan seguros con los instrumentos usados en la recolección del esos datos. Varios indicadores pueden ser usados en la evaluación, cuantificación y calificación del estímulo doloroso, y cuando se analizan en conjunto, permiten el desglose entre el dolor y los estímulos no dolorosos. Aunque sea deseable la estandarización objetiva para la medición de la intensidad del dolor, tal medida no existe todavía. La medición ene sea franja etaria es hecha por medio de parámetros fisiológicos (frecuencia cardíaca, frecuencia respiratoria, presión arterial, etc) y comportamentales (expresión facial, postura y vocalización o verbalización), utilizando escalas de evaluación, cada una con sus ventajas y limitaciones.
CONCLUSIONES: La actual atención para mejores métodos de medida y evaluación del dolor aportó para aumentar la sensibilidad de los profesionales de salud con relación a la naturaleza de las experiencias dolorosas. El dolor debe ser entendido como la quinta señal vital y evaluada de manera sistematizada, también en los recién nacidos.
The study of pain has had a great development in the last two decades, making its evaluation, and corresponding intervention, a growing concern among health professionals. Anand and Craig consider pain perception a quality inherent to life, being an early sign of tissue damage 1. These signs include behavioral and physiological responses that are valid indicators of pain, which can be evaluated by an observer.
The objective of pain evaluation should be to offer accurate data to determine the actions to be adopted to relieve or abolish them and, at the same time, evaluate the efficacy of those actions 2. Ideally, evaluation and treatment should be interdependent, because one is practically useless without the other. Strategies of pain treatment without a systematic evaluation are not effective or adequate. On the other hand, an excellent evaluation without rigorous treatment follow-up will not benefit the patient. Thus, in the clinical process of decision making, in which pain relief is the objective, the first step is a wide and adequate evaluation of the painful experience.
One should consider the whole constellation of aspects that could affect children response to pain, such as: anxiety, use of analgesics, the meaning of pain to the child, cultural norms, observation of other children with pain in the same area, duration of the pain, pain felt in the past, tiredness, degree of parental anxiety, learned behaviors, presence of health professionals, prior explanations about pain, use of psychological strategies to decrease pain, level of cognitive development, pain threshold, severity of the disease or physical damage, and learned family behavior 3.
It is important to mention that, up to now, a technique of pain evaluation in children, especially in newborns and infants, widely accepted, easy to administer, and uniform that can be used in every situation, is not available 1. Before trusting the accuracy of the evaluation data, health professionals should trust the instruments used to gather them. An instrument is valid if it really measures pain instead of other things as, for example, anger; it is reliable if their measurements are compatible and adequate for the situation 2.
One of the most problematic characteristics of pain severity is that, for the most part, it is more of a "state" than a "trait", since its severity does not remain stable long enough to evaluate the stability of the instrument used to measure it 4. Besides, in clinical practice, clinical usefulness is necessary for any measuring instrument, which should have a high degree of acceptability and convenience for those that use it. Useful clinical measurements give the users information to plan, implement, and evaluate the services.
Several indicators could be used to evaluate, quantify, and qualify the painful stimulus and, when they are analyzed as a set, allow the discrimination between pain and non-painful stimuli 5. Although an objective standardization to measure the severity of pain is desirable, it does not exist.
Pain activates compensatory mechanisms in the autonomous nervous system, producing responses that include changes in heart and respiratory rate, blood pressure, oxygen saturation, peripheral vasoconstriction, diaphoresis, dilation of the pupils, and increased release of catecholamines and adrenocorticosteroid hormones. However, the variation of those parameters might not be specifically related with a painful stimulus, but with several events, such as hunger, crying, discomfort, anxiety, or changes caused by the disease itself (shock, lung diseases, etc.). Due to accommodation and adaptation mechanisms that occur with physiological responses, these variations have been more useful in the examination of painful experiences associated with short duration procedures 6,7.
Another method of evaluating and measuring pain in children is based on the observation of their behavior (facial expression, posture, and vocalization or verbalization) 2. Several scales were developed to measure behavior in children in the presence of pain or discomfort. The discomfort refers to negative emotional responses triggered by sensory experiences of pain 8. Thus, a challenge for the use of behavioral methods is to differentiate discomfort and agitation from causes other than pain.
Similar to what happens with subjective measurements of pain, the stability of instruments that measure pain or behavioral discomfort tends to be low, due to its variable nature and related emotional states. Most observation instruments for children produce a total count that represents the sum of the number of values of severity in all items of the scale. The belief of the evaluator on the scale is also important, since two observers can "see" and interpret the same behavior in different ways. The reliability among evaluators increases when the behaviors are based on evaluation lists (present or absent) and when a reduced number of well-defined behaviors is used 2.
A problem with the use of behavioral methods is that health care professionals tend to underestimate pain in children when compared to self-reports. Parents also tend to underestimate the pain of their children; however, the values referred by them are closer to children self-reports than those done by the nursing staff 9.
Newborns are children in the pre-verbal stage and cannot describe their pain in words. Pain evaluation is indirect. Therefore, in those patients, it should be inferred from changes in behavioral and physiological parameters 10.
As mentioned before, behavioral indicators of pain include crying, facial expressions, and motor activity. Crying is considered a primary form of communication of the newborns, and its presence in the face of stress mobilizes the adult, may it be the mother or a health care professional involved in its care. However, it is not specific, and approximately 50% of newborns do not cry in response to a painful procedure 10. Besides, it can be triggered by other non-painful stimuli as hunger and discomfort. Some results seem to indicate that there is a specific cry of pain, however, the existence of this "cry of pain" has been questioned 11. Crying, as a measure of pain, seems to be a useful instrument, especially when it is associated with other measures of pain evaluation 5.
Facial expressions represent a sensitive, specific and useful sign in newborns at term and premature in pain evaluation, besides being a non-invasive method 5. Facial movements are significantly more expressive when infants are pricked on the heel or when the heels are rubbed. Regarding puncture of the heel, it has been observed that reactions of contraction of the brows, closing the eyes tight, deepening of the nasolabial folds and opening of the lips were present 99% of the time, and the reaction of stretching the tongue and tremors of the chin were present in 70% of infants short after the stimulus 12.
Analysis of the motor pattern demonstrated to be less sensitive and less specific than facial expression in premature and term neonates. This happens because, in premature neonates, motor responses tend to be less evident than in term infants, due to the hypotonic posture or associated systemic diseases 10.
The behavioral state of the patient in the moments preceding the painful stimulus affects the intensity of the response. Newborns in deep sleep demonstrate less pain, when changes in facial expressions are analyzed, when compared with those that are awake 12. The environment also interferes with the intensity of the response to the painful stimulus. For this reason, the room should be quiet, without much noise, with low luminosity, promoting the maximum comfort possible.
The scales used most often in this age group considering the particularities mentioned before are: the Neonatal Facial Coding System NFCS (Table I) 12 and the Neonatal Infant Pain Scale NIPS (Table II) 6. Other scales have used measuring tools, including behavioral parameters, to evaluate pain in specific situations, such as the postoperative period, like the Neonatal Postoperative Pain Evaluation Score (CRIES, Table III) 13. The COMFORT scale (Table IV) has been used in newborns on mechanical ventilation to evaluate sedation 14. The Premature Infant Pain Profile (PIPP, Table V) 15 is the most indicated for premature neonates because it takes into consideration changes specific to this group, and it has also been validated to be used in the postoperative period. In general, the clinical usefulness of those scales, especially regarding their use in premature and severely ill infants, is being validated 16.
The current concern with better measuring and evaluation methods increased the sensitivity of health care professionals regarding the nature of painful experiences. Quantification methods that incorporate the influence of contextual factors in the perception and response to pain are promising 10,17. Besides, new research on the mechanisms and processing of pain in children may lead to the development of new methods to measure pain in pre-verbal children.
Despite several theoretical subsidies and established indications to evaluate pain in the neonatal period, practice reveals timid initiatives of evaluation methods and to control pain in this age group 18. Some authors 19, after evaluating 17 Neonatal Intensive Care Units, established that all health care professionals believe that newborns feel pain. However, only two Units had written routines for the treatment of pain, and 30% to 90% of the newborns in each unit did not receive any analgesia during known painful procedures. The main difficulties to implement measures to control pain include: a) the absence of protocols to evaluate and treat pain in neonatal and pediatric units; and b) lack of theoretical knowledge on the pathophysiology of pain, evaluation methods, and treatment alternatives by the multi-professional team that handles those patients.
Thus, the main objective of this report was to call attention to the fact that pain in newborns should be valued as the fifth vital sign, and that it should be systematically evaluated and treated, using previously established protocols, abolishing, therefore, empiricism and undertreatment. This culture should be incorporated to the daily chores of the units instead of routines to be used in specific situations. Once this behavioral pattern has been spread, the lack of pain evaluation and treatment in those fragile patients, who are often exposed to painful and stressful procedures, becomes a transgression.
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Submitted em 12 de julho de 2006
Accepted para publicação em 12 de junho de 2007
* Received from Hospital Life Center e Faculdade de Medicina da Universidade Federal de Minas Gerais (FM/UFMG), Belo Horizonte, MG