Meconium aspiration

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Classification according to ICD-10
P24.0 Newborn meconium aspiration
ICD-10 online (WHO version 2019)

A meconium aspiration ( Mekoniumaspirationsyndrom, MAS ) refers to the penetration of meconium into the lungs of the newborn before or during birth and subsequent symptoms associated with it. Meconium, also called “Kindspech”, is the intestinal contents of the fetus and the feces of the newborn in the first days of life.

The meconium aspiration syndrome is preceded by a premature discharge of the meconium into the amniotic fluid. Amniotic fluid containing meconium is by no means rare, as 13% of all living newborns are born from amniotic fluid containing meconium. Of these children, 5% -12% will develop MAS.

Triggering event for a MAS

The development of a MAS is usually preceded by a fetal emergency (e.g. insufficient oxygen supply to the tissues = hypoxia ) or an inadequate blood flow in the fetus ( ischemia ). Due to the fetal stress or shock situation with redistribution of blood flow to the vital organs ( heart and brain ), the gastrointestinal tract of the fetus is initially insufficiently supplied with blood, but in the further course there is reactive hyperperistalsis (increased bowel movement) and in connection with a Analsphinkter- relaxation ( sphincter -Erschlaffung) for passage of meconium into the amniotic cavity comes. Since the unborn as part of the oxygen deficiency vigorous respiratory efforts (perhaps gasping be triggered), the floating in the amniotic fluid meconium can penetrate deep into the respiratory tract.

Diseases associated with MAS

The following diseases are frequently associated with MAS:

Chest x-ray of a female newborn (1 day old) with meconium aspiration

Clinical signs of a MAS

Children smeared with meconium need not necessarily have developed meconium aspiration. Quite a few children empty meconium due to the stress of birth. Especially in the second stage when the child through the press blow temporarily experiencing a lack of oxygen, it can empty meconium. However, once the child's head has entered the birth canal , it cannot aspirate meconium. If the child does not show normal vitality immediately after birth and the following symptoms are present at the same time, a meconium aspiration must be assumed with a high probability:

  • No or severely reduced muscle tone (the child is limp)
  • No or no normal breathing (instead of vigorous screaming, the child only whimpers or moans), it has obvious difficulty breathing and shows retractions in the intercostal spaces, on the diaphragm and jugulum , a nostril and a blue discoloration of the skin and mucous membranes ( cyanosis )
  • Visible mekonium smeared skin, meconium in the skin folds and in the body orifices such as ears, nostrils, mouth and throat
  • Greenish discolored skin, fingernails or umbilical cord (usually indicates that the meconium was removed some time ago)

Treatment strategy for meconium aspiration

It is assumed that a significant proportion of the newborns with MAS suffered it before the actual birth process began and that measures taken in the immediate postnatal course to avoid MAS in these children ultimately only bring marginal success. The previously recommended procedure for amniotic fluid containing mekonium, generally aspirating the children in the throat after the child's head and shoulder had developed ( intrapartum aspiration ), followed by tracheal aspiration after the child was completely born, the incidence (frequency of disease) of MAS could in any case not be significantly demonstrated to reduce. If there is amniotic fluid containing mekonium or if the child is smeared with mekonium, it should be sucked thoroughly in the mouth and throat as early as possible. If the child then shows unimpaired breathing and sufficient muscle tone, it can initially continue to be cared for like a healthy-born child, whereby it should be monitored more closely during the further course. In children with insufficient or insufficient muscle tone, who do not breathe or breathe inadequately, however, a ventilation hose ( endotracheal tube ) should be inserted into the windpipe ( endotracheal intubation ) and as much aspirated meconium removed using a suction device. In the case of thick meconium in the larynx (larynx), irrigation of the trachea and bronchi ( endotracheal lavage ) with a diluted surfactant solution to wash out the meconium may be attempted. This is followed by mechanical ventilation, if necessary measures to stabilize the circulation are taken and the child is subjected to intensive medical monitoring and therapy in a children's intensive care unit.

Pathological processes after meconium aspiration

If a large amount of meconium gets into the airways, the child cannot adequately ventilate its lungs immediately after birth, causing shortness of breath . The child shows classic signs of postnatal adjustment disorder of breathing, with accelerated breathing ( tachypnea ), difficult breathing ( dyspnea ), a groaning or creaking breath noise, retraction of the intercostal spaces ( intracostal retraction ) and the sternum (sternal retraction) as well as a visible blue discoloration of the skin and mucous membranes ( cyanosis ). Depending on the duration and severity of the shortness of breath and the resulting hypoxia, the child can also experience severe cardiovascular depression. In the case of severe and, above all, prolonged ( protracted ) intrauterine oxygen deficiency conditions, the child can be born without any signs of life ( asphyxia palladia = white asphyxia) and must be immediately given cardiovascular resuscitation .

The inhaled meconium creates areas in the child's lungs with inadequate ventilation ( atelectasis ), while other areas are overstretched or inflated ( pulmonary emphysema ). With overinflation, the tough meconium in the airways acts like a valve . Respiratory gas is in the positive pressure ventilation may be over the meconium into the downstream alveoli blown, but can not escape during exhalation by the meconium and remains in the lungs. The affected areas of the lungs can no longer breathe out sufficiently and become over-inflated. The consequences of such uneven ventilation of individual lung areas can be clearly seen in the x-ray of the lungs ( chest x-ray ). The radiologist found a " mixed picture of diffuse insufficient ventilation (atelectasis) with simultaneously existing areas of overinflation (emphysema) ". Very often a pneumothorax occurs in such a situation . The very thin membrane of the overstretched alveoli ruptures and breathing gas then escapes from the alveoli into the pulmonary connective tissue ( interstitial emphysema ). If this accumulation of gas located outside the alveoli then connects to the pleural space, the adhesion of the two pleural leaves is removed there and the lungs contract due to their own elasticity. This can result in an acutely life-threatening situation for the child. Another complication of the accumulation of meconium in the airways is reactive pneumonia (pneumonia) and inactivation of lung stabilizing factor ( surfactant ). Until 15-20 years ago, MAS was a difficult-to-treat disease in newborns with a high mortality rate. Today, MAS treatment results include special ventilation techniques , antibiotic therapy , inhalative nitric oxide therapy (iNO) and, above all, the administration of lung stabilizers extracted from animal lungs Factor ( surfactant substitution ) has been significantly improved. The ECMO requirement for newborns with this clinical picture has continuously decreased over the past 10 years.

Meconium clogged breathing tube

Bibliography

  1. ^ A b T. E. Wiswell, CM Gannon et al.: Delivery room management of the apparently vigorous meconium-stained neonate: results of the multicenter, international collabrative trial. In: Pediatrics. 2000; 105, pp. 1-7.
  2. ↑ M. Obladen: Newborn intensive care . 6th completely revised edition. Springer publishing house.
  3. ↑ SN Ahanya, J. Lakshmanan, BL Morgan, MG Ross: Meconium passage in utero: mechanisms, consequences, and management. In: Obstet Gynecol Surv. 2005 Jan; 60 (1), pp. 45-56.
  4. ↑ HS Falciglia: Failure to prevent meconium aspiration syndrome.
  5. ^ RO Davis, JB Philips, BA Harris, Jr, ER Wilson, JF Huddleston: Fatal meconium aspiration syndrome occurring despite airway management considered appropriate. In: Am J Obstet Gynecol. 1985; 151, pp. 731-736.
  6. ^ RF Soll, P. Dargaville: Surfactant for meconium aspiration syndrome in full term infants. In: Cochrane Database Syst Rev. 2000; (2), S. CD002054.

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