Pulmonary surfactant (surfactant).

The surfactant is a complex of surfactant substances which have the function of preventing the collapse of the pulmonary alveoli during exhalation (atelectasis).

The alveoli

The pulmonary alveoli play an important role in our respiratory system.

These are small air sacs/small cavities where gas exchanges between the blood and the atmosphere take place. Inside them, the blood is enriched with the oxygen contained in the air we inhale and releases the carbon dioxide produced by our tissues.

In this way, our blood receives the oxygen it needs to survive. The same goes for a newborn too.

As air enters the lungs, the alveoli fill and expand; as the air leaves the lungs they become smaller.

During the second phase, that of expiration, it is important that the alveoli do not “deflate” to the point of collapsing and leading to an absence of air in the alveoli involved, ie to pulmonary atelectasis (atelectasis).

The function of the pulmonary surfactant (or surfactant) is precisely to prevent the absence of air in the affected alveoli (atelectasis) during the expiration phase.

What is pulmonary surfactant

The surfactant (from the English  surf ace  act ive  a ge nt ) or pulmonary surfactant, is a coating of the inner lining of the alveoli which favors the expansion of the alveoli during respiration and which, as we have just said, also prevents the collapse and crushing of the alveoli during expiration.

The endogenous surfactant is biologically produced in the lungs between the  24th  and  35th  week of pregnancy, i.e. between the 6th and 8th month of pregnancy.

By 35 weeks of gestation, most newborns have enough surfactant to breathe well.

What happens to the premature baby?

Babies who are born before  37 weeks of pregnancy  are termed “premature”.

If a baby is premature, or born too soon, it may not have enough endogenous surfactant or surfactant in its lungs to breathe properly: in babies born prematurely, the surfactant coating may be bumpy or sticky, and when the baby breathes the alveoli can collapse and stick together.

With every single breath, the baby born prematurely has to work very hard to open the alveoli, and this fact makes his breathing much more difficult.

For these reasons it is necessary to provide it with an additional surfactant (a surfactant), an exogenous surfactant. This will keep his alveoli from collapsing on exhalation, making it easier for him to breathe.

Surfactant treatments

Therapeutic treatments with exogenous surfactant are able to improve respiratory insufficiency and modify the clinical prognosis of the premature baby. Indeed,

  • both the exogenous surfactant obtained from animals – a liquid that is taken from the lungs of the cow and which is subsequently purified -,
  • both the synthetic one, that is the surfactant that is produced in the laboratory,

reduce both respiratory morbidity and mortality in infants born prematurely.

NB : synthetic surfactants with protein-like activity appear to be particularly promising.

In exogenous surfactant treatment, a liquid surfactant is placed in the newborn’s endotracheal tube and connected to a mechanical ventilator.

The ventilator gently blows oxygen into the baby’s lungs, allowing him to breathe, and this fact keeps the alveoli slightly open so they don’t collapse.

The ventilator also helps move fluid to the bottom of the newborn’s lungs.

Signs of its positive effects

What are the signs indicating that the exogenous surfactant has been used by the child?

The signs demonstrating that the treatment just described had beneficial effects are given by the fact that,

  • the newborn breathes easier;
  • the baby needs less oxygen;
  • the fan is working less;
  • x-rays show that the baby’s alveoli are regular in shape and size;
  • a blood test – called “blood gases” – shows that the baby’s breathing is more effective.

Does it have any side effects?

Exogenous surfactant may increase the likelihood of continued fetal connection (ductus arteriosus) between the aorta and pulmonary artery after birth.

However, this problem can be treated in the neonatal ward.

Katherine Johnson, M.D., is a board-certified obstetrician-gynecologist with clinical expertise in general obstetrics and gynecology, family planning, women’s health, and gynecology.

She is affiliated with the Obstetrics and Gynecology division at an undisclosed healthcare institution and the online platform, Maternicity.com.

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