title: Dynamic surface tension of natural surfactant extract under superimposed oscillations.
abstract: Surfactant dysfunction plays a major role in respiratory distress syndrome (RDS). This research seeks to determine whether the use of natural surfactant, Curosurf™ (Cheisi Farmaceutici, Parma, Italy), accompanied with pressure oscillations at the level of the alveoli can reduce the surface tension in the lung, thereby making it easier for infants with RDS to maintain the required level of functional residual capacity (FRC) without collapse. To simulate the alveolar environment, dynamic surface tension measurements were performed on a modified pulsating bubble surfactometer (PBS) type device and showed that introducing superimposed oscillations about the tidal volume excursion between 10 and 70 Hz in a surfactant bubble lowers interfacial surface tension below values observed using tidal volume excursion alone. The specific mechanisms responsible for this improvement are yet to be established; however it is believed that one mechanism may be the rapid transient changes in the interfacial area increase the number of interfacial binding sites for surfactant molecules, increasing adsorption and diffusion to the interface, thereby decreasing interfacial surface tension. Existing mathematical models in the literature reproduce trends noticed in experiments in the range of breathing frequencies only. Thus, a modification is introduced to an existing model to both incorporate superimposed pressure oscillations and demonstrate that these may improve the dynamic surface tension in the alveoli.
authors.affiliation: Institute of Biomedical Technologies, Auckland University of Technology, Private Bag 92006, Auckland 1142, New Zealand.
authors.forename: Prasika I
authors.initials: PI
authors.lastname: Reddy
authors.forename: Ahmed M
authors.initials: AM
authors.lastname: Al-Jumaily
authors.forename: Geoff T
authors.initials: GT
authors.lastname: Bold
mesh_terms: D000818:Animals; D001688:Biological Products / Q000737:chemistry / Q000627:therapeutic use*; D001696:Biomechanical Phenomena; D045422:Continuous Positive Airway Pressure / Q000295:instrumentation / Q000379:methods; D005652:Functional Residual Capacity / Q000187:drug effects / Q000502:physiology; D006801:Humans; D066298:In Vitro Techniques; D007231:Infant, Newborn; D008954:Models, Biological; D010743:Phospholipids / Q000737:chemistry / Q000627:therapeutic use*; D011650:Pulmonary Alveoli / Q000187:drug effects / Q000503:physiopathology; D011663:Pulmonary Surfactants / Q000737:chemistry / Q000627:therapeutic use*; D012127:Respiratory Distress Syndrome, Newborn / Q000188:drug therapy / Q000503:physiopathology; D015656:Respiratory Mechanics; D012756:Sheep; D013500:Surface Tension; D013990:Tidal Volume
chemical_list: D001688:Biological Products; D010743:Phospholipids; D011663:Pulmonary Surfactants; C068291:poractant alfa