Pulmonary Surfactant: Dosage, Administration and Risks

It is a complex mixture of lipids, proteins and specific carbohydrates, secreted by the epithelial cells to the alveolar space.

Pulmonary surfactant is more specifically 80% phospholipids, 12% corresponds to proteins and 8% to other lipids.

Its main function is to reduce the surface tension at the air / liquid interface in the alveoli of the lung.

Premature babies who are born with immature lungs and have a deficiency of surfactant develop a syndrome of respiratory distress after being born.

The replacement therapy of pulmonary surfactant used in premature babies, during this last decade, has managed to significantly increase their survival and reduced the probability of significant pulmonary sequelae in the neonates.

Although premature babies are the primary population, treatment for respiratory diseases may play an important role in other diseases of this same type in full-term babies and older children.

However, this therapy, in the case of adult patients, has not reached the level of success observed in the child population.

Substitution therapy of natural surfactant by purified surfactant from lungs of non-human species is one of the most significant advances in neonatology.

These exogenous surfactants have been available for more than two decades, those of natural origin and synthetic ones are used.

Natural surfactants come from lung lavage or lung extracts from cattle or pigs.

These substances are subjected to extraction and purification processes, and the addition of supplementary compounds is required to achieve an optimum activity of decreasing the surface tension.

Synthetic surfactants originate from the mixture of phospholipids, proteins and supplementary compounds to provide activity as an active tensing agent.

Dosage

To estimate the dosage, the amount of phospholipids to be supplied per body weight should be taken into account.

The only disease, where the estimates of the dosage have been studied, is in the neonatal respiratory distress syndrome.

The recommended phospholipid dose is 100 mg / kg of weight.

The frequency with which the application of the active tense agent is performed will depend on the clinical condition of the patient.

The repetition of the treatment is usually done at intervals of 6 to 24 hours.

Administration of pulmonary surfactant therapy

Different methods for administering the therapy include intratracheal bolus administration through an endotracheal tube, aerosolization and bronchoscopic administration of the dilute active surfactant to remove mediators and inhibitors of inflammation.

At this time, the administration of the treatment is done in bolus due to its relative ease.

The replacement of pulmonary surfactant can be provided as: prophylactic or preventive treatment in which the surfactant is administered at birth or shortly after in infants, with high risk of developing the disease and therapeutic treatment in which surfactant is administered after the start of mechanical ventilation in newborns with clinically confirmed syndrome, according to clinical data and chest x-ray.

To start treatment, hypothermia, hypoglycaemia, and hypovolaemia must be controlled as they are essential aspects of the treatment and its correction is recommended before the administration of the active tense agent.

Treatment begins with the placement of a saturation probe and monitoring of oxygen saturation should be performed.

Prior chest radiographs should be performed to confirm the diagnosis and ensure proper placement of the endotracheal tube before administration of the pulmonary surfactant.

Monitoring of heart rate and / or oxygen saturation is required after starting assisted ventilation.

The placement of a peripheral arterial line or umbilical arterial line is desirable, but optional.

Antibiotics should be given to prevent infections.

Risks

Among the risks or side effects that may arise from the application of pulmonary surfactant therapy and the therapies that accompany it:

  • Infection
  • Hypotension
  • Blockage of the endotracheal tube
  • Bradicardia
  • Oxygen desaturation
  • Possibility of pneumothorax due to sudden changes in lung compliance
  • Irritation, which can cause bleeding in the lungs
  • Damage to lung tissue due to inadequate oxygen pressure

Some of the risks can be avoided by taking the necessary precautions, such as precise procedures and constant supervision.

It is necessary to document the date, schedule and response to administration in the patient’s progress notes.