Pulmonary surfactant - Wikipedia
Surfactant reduces the surface tension of fluid in the lungs and helps make Some very premature infants may also need to be placed on a mechanical ventilator. . Chicago Manual of Style, and the American Psychological Association (APA). of the mucosa, which may explain in part why our stomachs are not digested. Surfactant replacement therapy for premature babies acts to keep Imagine the difference between a straight skirt and a heavily pleated skirt. Pulmonary surfactant is a surface-active lipoprotein complex (phospholipoprotein ) formed by type II alveolar cells. The proteins and lipids that make up the surfactant have both hydrophilic and hydrophobic regions. By adsorbing to the air -water interface of alveoli, with hydrophilic head It reduces the pressure difference needed to allow the lung to inflate.
It is important to use a delivery strategy that optimizes surfactant distribution into the pulmonary airways to maximize its beneficial effects 2.
Inthe Committee on Fetus and Newborn — American Academy of Pediatrics published a clinical report on the use of surfactant replacement therapy for respiratory distress in the preterm and term neonate 1. Unfortunately, the scientific literature provides conflicting and limited data regarding the methods or techniques of surfactant administration.
Moreover, respiratory care has changed substantially since these studies were conducted. Exogenous surfactant preparations must spread rapidly and efficiently into the air-liquid interface once instilled in the proximal airways, with the goal of achieving a homogenous distribution throughout the lungs. However, rapid administration of liquid into the lungs may elicit transient oxygen desaturation and bradycardia, or significant complications such as severe airway obstruction, pulmonary hemorrhage, pneumothoraces or pulmonary hypertension 3.
Therefore, surfactant should be administered according to a well-established protocol under the supervision of clinicians and respiratory therapists experienced in tracheal intubation, ventilator management and general care of the premature infant. The present article reviews several aspects of administration techniques that can influence the delivery of surfactant into the lungs: A surfactant administration protocol that was developed and implemented in our unit, based on the best available evidence, is included in Appendix 1.
Surfactant has also been given by nebulization; however, because this method and preparation remain under investigation, it will not be reviewed here. When rapid bolus infusions were compared with slow bolus or continuous infusions in several animal studies, they were noted to be superior in terms of overall distribution of the surfactant and a faster rate of improvement of oxygenation and lung compliance 56.
However, side effects, such as transient bradycardia and decreased blood pressure, were noted with rapid bolus administration. At present, the rapid bolus technique remains the recommended method of surfactant administration.
Cassidy et al 7 showed that the method of liquid instillation affects how the liquid distributes within the lung.
The best method allowed the formation of a liquid plug in the trachea at the beginning of surfactant instillation. The liquid was then driven to the distal parts of the lung by ventilation, resulting in quicker spread in a few breaths and more uniform liquid distribution throughout the lungs.
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Transit and delivery times depend on plug volume, among other factors. Although the exogenous surfactant takes in the order of minutes to reach the alveoli, the lowering of surface tension at the distal ends occurs very rapidly — within seconds — as the result of the compression of the endogenous surfactant 8. This could lead to overinflation of the parts of the lung receiving surfactant and result in bronchopulmonary dysplasia 6.
Improved homogeneity is achieved with supine compared with upright positioning. Animal models have also shown greater epithelial cell injury at slower propagating speeds In a randomized control trial 11there was no difference in clinical outcomes when two fractional doses of surfactant were given in two body positions, compared with four fractional doses given in four positions.
Ventilation during all three procedures was performed by using pre-treatment pressures: There were no significant differences among the three procedures. A similar study was conducted by Valls-i-Soler et al 12who compared two methods. The first was bolus delivery two aliquots of poractant alfa at a volume of 2. The second method was delivery via a side hole, in which a full dose of surfactant was rapidly given in 60 s via a 3.
Both procedures were equally effective, but a slight significant increase in the partial pressure of carbon dioxide PCO2 at 5 min of dosing was observed in the side-hole group, indicating decreased minute ventilation, likely related to some degree of airway obstruction.
A prospective study was performed in smaller and more immature preterm infants receiving their first or second dose of surfactant while being ventilated in assist control volume guarantee mode A small volume of poractant alfa 1.
Ventilator parameters were recorded before, during and after administration. A significant and prolonged decrease in the delivered tidal volume obstruction was noted in the majority of the infants. RDS tends to be less severe in babies whose mothers received steroid treatment before delivery.
Surfactant administration in neonates: A review of delivery methods
Treatment for RDS Fortunately, surfactant is now artificially produced and can be given to babies if doctors suspect they are not yet making surfactant on their own.
Most of these babies also need extra oxygen and support from a ventilator. Pneumonia Pneumonia is an infection of the lungs. Some babies get pneumonia while they are still in the womb and must be treated at birth. Babies may also develop pneumonia several weeks after delivery. This is usually because they were on a ventilator for respiratory problems like respiratory distress syndrome or bronchopulmonary dysplasia.
Treatment for pneumonia Babies with pneumonia often need to be treated with an increased amount of oxygen or even mechanical ventilation a breathing machinein addition to antibiotics.
Apnea of prematurity Another common respiratory problem of premature babies is called apnea of prematurity. This occurs when the baby stops breathing. It often causes the heart rate and oxygen level in the blood to drop. Apnea occurs in almost percent of babies who are born before 28 weeks gestation. Apnea usually does not happen immediately after birth. It occurs more commonly at 1 to 2 days of age and sometimes is not obvious until after a baby has been weaned from a ventilator.
There are two main causes of apnea in premature infants. The baby "forgets" to breathe, simply because the nervous system is immature. This is called central apnea. This helps reduce the need for surfactant replacement therapy. Although babies of all races may be born prematurely, prematurity is more common if the mother is diabetic, is carrying multiple fetuses, or has delivered a previous premature baby.
The decision to use surfactant replacement therapy is based on the condition of the baby, its blood oxygen level, and degree of respiratory distress. Aftercare Babies receiving surfactant therapy are normally cared for by a neonatologist, a pediatrician that specializes in newborn care. Premature newborns often have other health problems in addition to RDS.
Aftercare varies depending on their other health risks.
Surfactant administration in neonates: A review of delivery methods
Risks Delivery of surfactant requires inserting a breathing tube into the baby's lungs. Complications of this therapy include air leaking into the area between the chest wall and the lungs and air leaking into the sac around the heart.
Some infants also develop chronic lung disease. Normal results Normally surfactant replacement therapy keeps the infant alive until the lungs start producing their own surfactant. Abnormal results Surfactant replacement therapy is very effective if begun within six hours after birth.
When it fails, death may result. Lucile Packard Children's Hospital at Stanford. Respiratory Distress Syndrome, 2 July [cited 16 February ].
Johns Hopkins School of Medicine. Hyaline membrane— A thin layer of cells that line the lung. Surface tension— The attraction of molecules in a fluid for each other.