Síndrome de muerte súbita del lactante

Sinónimos: muerte súbita del lactante (especialmente entre el público en general)

Resumen

¿Qué es el síndrome de muerte súbita del lactante?

El síndrome de muerte súbita del lactante (SMSL) describe la muerte repentina e inexplicada de un niño menor de 1 año. Es un evento trágico que supone un impacto devastador para las familias involucradas.

Sudden infant death syndrome is defined as the sudden and unexpected death of an infant under 1 year of age, apparently occurring during sleep, which remains unexplained after a thorough investigation including a complete autopsy and review of the circumstances of death. All other possible causes of death must be excluded for this diagnosis to be made.¹

The terms 'sudden and unexpected infant death' (SUID) or 'sudden unexpected death in infancy' (SUDI) are sometimes used to describe all deaths, regardless of cause. Cases of SUID that remain unexplained after post-mortem examination and review of the history and circumstances surrounding the death are classified as sudden infant death syndrome. The remainder have a clear cause such as severe infection, inherited disorders of fatty acid oxidation or genetic cardiac channelopathies.

Whilst the pathogenesis of SIDS is not yet fully elucidated, there is evidence that an important subset of SIDS infants have serotonergic abnormalities resulting from a problem in the medullary reticular formation which is comprised of nuclei that contain serotonin neurons. This lesion could lead to a failure of protective brainstem responses to homeostatic challenges during sleep in a critical developmental period which cause sleep-related sudden death. This is known as the serotonin brainstem hypothesis.²³

• En el hemisferio occidental, el síndrome de muerte súbita del lactante es la causa más común de muerte en niños entre 1 mes y 1 año de edad.

• In England and Wales in 2023:

  • There were 164 unexplained deaths of infants, of which 52% were due to SIDS. This is similar to recent years.

  • Male and female infants were equally as likely to have an unexplained death, the first year for which this has been the case since 2017 - in all the intervening years there was a male predominance.

• Since 2004, the sudden infant death mortality rate has halved to 0.16 deaths per 1,000 live births in 2019, due to public information campaigns aimed at ending prone sleeping for infants.

Although sudden infant death syndrome cannot be prevented, there are several factors which are known to be associated with increased risk.

En 1994 se propuso un 'Modelo de Triple Riesgo', que enfatiza el papel y la interacción de varios factores en la patogénesis del SMSL.

En este modelo, el SMSL ocurre cuando tres factores están presentes simultáneamente.

Estos factores son:

• Una vulnerabilidad subyacente en el bebé, por ejemplo, bajo peso al nacer o prematuridad.

• A critical developmental period - usually 1-3 months of age.

• Un 'estresor exógeno', por ejemplo, dormir boca abajo. Se cree que una combinación de sistemas de control cardiorrespiratorio inmaduros y una falla en despertarse del sueño conducen a la muerte.

Tabaquismo materno y SMSL⁵⁶

• Maternal smoking is a risk factor for sudden infant death syndrome - SIDS is more frequently observed in infants of smoking mothers.

• The level of risk due to smoking is dose-dependent and passive exposure to smoke during infancy has also been shown to increase the risk.

• If both parents smoke, the risk is further increased.

Otros factores de riesgo materno^{1 4}

Históricamente, se ha demostrado que algunas otras características maternas están asociadas con un mayor riesgo de síndrome de muerte súbita del lactante. Estas incluyen:

• Abuso de alcohol y sustancias. Esto se convierte en un problema adicional cuando hay compartición de cama con el bebé (discutido a continuación).

• Age less than 20 at first pregnancy.

• Pobreza o estatus socioeconómico bajo.

• Sin relación de apoyo.

• Low birthweight.

• Age under 4 months.

• The mother having 2 or more previous children.

Parto prematuro

Prematuridad is associated with a four-fold increased risk of sudden infant death syndrome. This may be partly related to the fact that preterm babies are often placed prone whilst in special care baby units in order to improve respiratory function. It is important that they get used to sleeping on their back before discharge.

Otros factores de riesgo obstétrico

• Atención prenatal tardía o inexistente.

• Bajo aumento de peso durante el embarazo.

• Anomalías placentarias. Tales anomalías pueden explicar el bajo peso al nacer, que es un factor de riesgo para el SMSL.

Posición para dormir

Prone sleeping is a major, modifiable risk factor and following campaigns to raise awareness of this, the numbers of cot deaths fell significantly.⁷ Placing babies on their backs to sleep is advice which should be reinforced by professionals. Parents should be reassured that the risk of aspiration is not increased by sleeping in this position and a number of studies have confirmed this.

Bed-sharing⁸⁹

The issue of advising parents about sharing a bed with their baby is a potentially sensitive one and has received much prominence in the literature of late. Although it is a very common practice worldwide, there is emerging evidence that co-sleeping does increase the risk of SIDS when the parents smoke or have drunk alcohol that day. The evidence about co-sleeping when there are no other risk factors (such as cigarettes or alcohol) is more variable, with some reviews suggesting that the risk persists and others that it does not. Falling asleep on a chair or sofa with a baby is more dangerous than bed sharing.

The National Institute for Health and Care Excellence (NICE) guidance on postnatal care, updated in 2021,¹⁰ did not make a blanket recommendation against bed sharing - it included two recommendations in this area:

• Discuss with parents safer practices for bed sharing, including:

  • Making sure the baby sleeps on a firm, flat mattress, lying face up (rather than face down or on their side)

  • Not sleeping on a sofa or chair with the baby.

  • Not having pillows or duvets near the baby

  • Not having other children or pets in the bed when sharing a bed with a baby.

• Strongly advise parents not to share a bed with their baby if their baby was low birth weight or if either parent:

  • Has had 2 or more units of alcohol.

  • Smokes.

  • Has taken medicine that causes drowsiness.

  • Has used recreational drugs.

The 2022 NICE quality statement on postnatal care ¹¹ also advises that parents should be given advice about safer practices for bed sharing, rather than advising against the practice in all cases.

Department of Health and the Lullaby Trust (formerly the Foundation for the Study of Infant Deaths) advice is that the safest place for babies to sleep in the first six months of life is in a separate Moses basket or cot, in the parental bedroom.¹² They also have a resource for patients which contains advice about bed sharing. ¹³It covers many of the same points as the NICE guidance and also advises that bed sharing is less safe if the baby was premature.

Ropa de cama

La evidencia muestra que la ropa de cama ha cubierto la cabeza del bebé en un número significativo de muertes por SMSL. La ropa de cama blanda aumenta el riesgo de síndrome de muerte súbita del lactante cinco veces y mucho más si el bebé está boca abajo.

Therefore, advice to parents is: ¹²

• No se deben usar edredones, colchas y almohadas.

• La cabeza del bebé no debe estar cubierta.

• Un saco de dormir para bebés es teóricamente más seguro que las mantas. Sin embargo, cuando se utilizan mantas, estas deben ser delgadas y el bebé debe colocarse con los pies en el pie de la cuna. Las mantas deben estar metidas por tres lados de tal manera que no lleguen por encima de las axilas del bebé.

• Los colchones deben ser firmes.

• La temperatura de la habitación debe estar entre 16-20°C y se debe verificar a los bebés para asegurarse de que sientan una temperatura adecuada.

The following are associated with a reduced risk of sudden infant death syndrome: ¹

• Breastfeeding. Reduces risk; risk is further reduced if exclusively breastfeeding, compared to partial breastfeeding. ¹⁴

• Dummies. There is consistent evidence that babies who die from SIDS are less likely to have used a dummy in their final sleep. However, advice varies, as dummies are thought to possibly reduce the length of breastfeeding time and therefore have other disadvantages. A Cochrane review failed to demonstrate that dummies have either a positive or a detrimental effect on risk of SIDS, but a US task force concluded that there is a protective effect. The studies on which they based this conclusion were largely done some years before the Cochrane review.¹⁵¹⁶

• Room-sharing. A baby sleeping in the parental bedroom has a reduced risk of SIDS by possibly as much as 50%. Advice from the Lullaby Trust is therefore that babies should sleep in the parental bedroom (but not in the parental bed) for the first six months of life.

The sudden death of a child is very traumatic for all concerned, including the attending doctor. Parents will be in a state of shock and any professional attending will need to be sensitive and considerate in their handling of the family.

Es poco probable que los médicos de cabecera estén involucrados en atender una muerte súbita infantil, pero en caso de hacerlo, lo siguiente puede ser útil:

• Al observar por primera vez al bebé, tome nota de la posición en la que está acostado, la ropa que lleva puesta y cualquier secreción, etc., en la cara del niño, y haga un registro preciso de estas observaciones lo antes posible, para tener notas contemporáneas.

• Una vez que se ha establecido que la muerte ha ocurrido, la preocupación inicial debe ser por el/los padre/s y otros miembros de la familia presentes. Después de darles un poco de tiempo para aceptar el hecho de la muerte, se les debe explicar suavemente que todos los casos de muerte súbita por cualquier causa deben ser reportados al forense o, en Escocia, al procurador fiscal, que los oficiales de policía acudirán y que este es un proceso rutinario y no debido a ninguna circunstancia sospechosa.

• Pregunta si hay alguien a quien puedas llamar para que venga a quedarse con ellos o cuidar a los hermanos, especialmente en el caso de padres solteros.

• Es probable que la familia del niño necesite apoyo durante el período de investigación y duelo, y la muerte debe ser reportada a su médico habitual y visitante de salud lo antes posible.

Sugerencias para los médicos generales incluyen:

• No evites el contacto. Incluso una llamada breve es apreciada.

• Expresa tu simpatía y pesar y tu disponibilidad para brindar apoyo continuo. Pregunta si puedes hacer algo de inmediato.

• Usa el nombre del bebé.

• Asegúrese de que los padres tengan los datos de contacto de Lullaby Trust para obtener apoyo y asesoramiento.

• Evita pedirle a los padres que te cuenten sobre el evento, a menos que estén interesados en hacerlo.

• Evita los clichés y las comparaciones con otros casos.

In some cases of sudden unexpected deaths in infancy, a post-mortem will identify a cause of death:¹⁷¹⁸

• Enfermedad

• Trastorno genético

• Lesión accidental

• Protección issues

El síndrome de evento aparentemente mortal solía llamarse casi muerte súbita del lactante. El término se eliminó ya que NO hay evidencia de asociación con un mayor riesgo de SMSL y la condición tiene una epidemiología diferente. Es un síntoma de presentación, no un diagnóstico.

• Afecta predominantemente a niños menores de 1 año.

• Hay síntomas alarmantes con alguna combinación de apnea, cambio de color, cambio en el tono muscular, tos o arcadas.

• Aproximadamente el 50% de estos niños son diagnosticados con una condición subyacente que explica el evento.

• Las causas más comunes son el reflujo gastroesofágico, las infecciones del tracto respiratorio inferior y las convulsiones.

• La causa sigue siendo desconocida en alrededor de la mitad.

The value of apnoea monitors is controversial, as they have not been proven to prevent sudden infant death syndrome. However, parents often feel reassured that they are 'doing everything they can', whilst using one.

There are a few cases, documented by covert video surveillance, in which parents have induced illness in their children. This can result in serious neurological damage and even death. The implications are discussed in the separate Fabricated or induced illness by carers (FII) article.

There are occasions when more than one infant death occurs within a family and explanations are sought. Siblings of SIDS infants have an increased risk of dying as a result of SIDS. Siblings are 5-6 times more likely than the general population to die from SIDS.¹ After investigation, not all sibling deaths can be attributed to SIDS. Sibling deaths have also been found to be attributable to inborn errors of metabolism, abuse, and malnourishment.

The Care of the Next Infant (CONI) programme is available throughout most of the UK. It provides specialist support to parents who have lost an infant to SIDS, throughout their next pregnancy and for the first six months after their next baby is born. ¹⁹

El SMSL no se puede prevenir completamente, pero la experiencia muestra que se puede reducir. Esto requiere atención a los diversos factores de riesgo mencionados anteriormente. En particular, es importante el consejo de colocar al bebé a dormir en posición supina en el dormitorio de los padres y evitar el tabaquismo parental.

Supine sleeping position has, however, increased the incidence of flattening of the occiput (deformational plagiocephaly).²⁰ To try to prevent this, infants should have supervised 'tummy time' when awake - spending as much time as possible in the prone position. The use of helmet therapy remains controversial.