Surfactant displacement by meconium free fatty acids: An alternative explanation for atelectasis in meconium aspiration syndrome

doi:10.1016/S0022-3476(87)80021-5

The Journal of Pediatrics

Volume 110, Issue 5, May 1987, Pages 765-770

https://doi.org/10.1016/S0022-3476(87)80021-5 Get rights and content

Meconium, an ether extract of meconium, and the major free fatty acids of meconium (paimitic, stearic, and oleic acids) were all found to increase the surface tension minimum of dog lung extract in a Wilhelmy balance. Each of these fractions was instilled into the lungs of dogs (15 experimental, egith saline solution controls), and cardiac output, venous and arterial blood gases, pulmonary, atrial, and systemic pressures, airway pressure, and static lung compliance were serially monitored for 2 hours. Mean airway pressure increased and static lung compliance decreased significantly in all of the experimental groups. Although arterial pH and Paco₂ and the various hemodynamic measurements did not change during the experiment, Pao₂ decreased significantly and did not return to baseline in all experimental groups. Extracts from atelectatic portions of experimental dog lung had a surface tension minimum of >20 dynes/cm, whereas airway foam had a surface tension minimum of <10 dynes/cm, suggesting that the free fatty acids of meconium are able to strip surfactant from the alveoli.

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Citation Excerpt :
The primary reason that endotracheal suction was unable to reduce the risk of MAS significantly could be because of both meconium passage and aspiration occur in utero and the tracheal suctioning is unlikely to benefit as meconium already is in the distal lung at the time of birth.22 Also, other mechanisms including surfactant inhibition,23 chemical pneumonitis,24 persistent pulmonary hypertension of the newborn,25 and secondary infection26 may contribute to MAS. The association of low 1- and 5-minute Apgar scores with MSAF was described in 1980 by Krebs et al.27 In the more recent studies by Sheiner28 and Mundhra,29 which included both vigorous and nonvigorous infants, 5-minute Apgar was not significantly lower in babies with meconium stain compared with controls.
To assess whether endotracheal suctioning of nonvigorous infants born through meconium stained amniotic fluid (MSAF) reduces the risk and complications of meconium aspiration syndrome (MAS).
Term, nonvigorous babies born through MSAF were randomized to endotracheal suction and no-suction groups (n = 61 in each). Risk of MAS, complications of MAS and endotracheal suction, mortality, duration of neonatal intensive care unit stay, and neurodevelopmental outcome at 9 months were assessed.
Maternal age, consistency of meconium, mode of delivery, birth weight, sex, and Apgar scores were similar in the groups. In total, 39 (32%) neonates developed MAS and 18 (14.8%) of them died. There were no significant differences in MAS, its severity and complications, mortality, and neurodevelopmental outcome for the 2 groups. One infant had a complication of endotracheal suctioning, which was mild and transient.
The current practice of routine endotracheal suctioning for nonvigorous neonates born through MSAF should be further evaluated.
Clinical Trial Registry of India: CTRI/2013/03/003469.

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Surfactant displacement by meconium free fatty acids: An alternative explanation for atelectasis in meconium aspiration syndrome

J Pediatr

Biochim Biophys Acta

J Surg Res

Am J Obstet Gynecol

Am J Obstet Gynecol

Meconium aspiration syndrome

Pediatr Clin North Am

Mechanical and chemical damage to lung tissue caused by meconium aspiration

Pediatrics

The therapeutic application of end-expiratory pressure in the meconium aspiration syndrome

Pediatrics

Assisted ventilation in infants with meconium aspiration syndrome

Pediatrics