Despite their broad clinical use, there is no standardized comparative study on the functional, biochemical, and morphologic differences of the various commercial surfactants in relation to native surfactant. We investigated these parameters in Alveofact, Curosurf, Exosurf, and Survanta, and compared them with native bovine (NBS) and porcine (NPS) surfactant. For Curosurf and Alveofact the concentrations necessary for minimal surface tensions < 5 mN/m were six to 12 times higher (1.5 and 3 mg/ml, respectively) than with NPS and NBS. Exosurf and Survanta only reached 22 and 8 mN/m, respectively. Increasing calcium to nonphysiologic concentrations artificially improved the function of Alveofact and Curosurf, but it had little effect on Exosurf and Survanta. Impaired surface activity of commercial versus native surfactants corresponded with their lack in surfactant protein SP-A and decreased SP-B/C. The higher surface activity of Curosurf compared with Alveofact corresponded with its higher concentration of dipalmitoylphosphatidylcholine (DPPC). Despite their enrichment in DPPC Survanta and Exosurf exhibited poor surface activity because of low or absent SP-B/C. Ultrastructurally, Curosurf and Alveofact consisted mainly of lamellar and vesicular structures, which were also present in NPS and NBS. Exosurf contained crystalline structures only, whereas the DPPC-enriched Survanta contained separate lamellar/vesicular and crystalline structures. We conclude that in vitro surface activity of commercial surfactants is impaired compared with native surfactants at physiologic calcium concentrations. In the presence of SP-B/C, surface activity corresponds to the concentration of DPPC. Our data underscore the importance of a standardized protocol at physiologic calcium concentrations for the in vitro assessment of commercial surfactants.

https://www.atsjournals.org/doi/pdf/10.1164/ajrccm.162.4.9908104

Commercial versus native surfactants. Surface activity, molecular components, and the effect of calcium.

Devices, compositions, and methods for achieving non-surgical lung volume reduction (e.g., bronchoscopic lung volume reduction (BLVR)) are described. BLVR can be carried out by collapsing a region of the lung, adhering one portion of the collapsed region to another, and promoting fibrosis in or around the adherent tissue.

Tissue volume reduction

▪ Abstract The field of respiratory flow and transport has experienced significant research activity over the past several years. Important contributions to the knowledge base come from pulmonary and critical care medicine, surgery, physiology, environmental health sciences, biophysics, and engineering. Several disciplines within engineering have strong and historical ties to respiration including mechanical, chemical, civil/environmental, aerospace and, of course, biomedical engineering. This review draws from a wide variety of scientific literature that reflects the diverse constituency and audience that respiratory science has developed. The subject areas covered include nasal flow and transport, airway gas flow, alternative modes of ventilation, nonrespiratory gas transport, aerosol transport, airway stability, mucus transport, pulmonary acoustics, surfactant dynamics and delivery, and pleural liquid flow. Within each area are a number of subtopics whose exploration can provide the opportunity of both...

Respiratory Fluid Mechanics and Transport Processes

Phase transitions in films of lung surfactant at the air-water interface

Interfacial transport processes and rheology

A bubble surfactometer was used to measure the surface tension of an aqueous suspension of surfactant TA as a function of bubble area over a range of cycling rates and surfactant bulk concentration...

Dynamic surface tension of surfactant TA: experiments and theory

A previously developed adsorption-limited model [Otis, 1994; Ingenito, 1999] that describes the transport of lung surfactant to and from an air-liquid interface has been extended to allow for diffusion in the bulk phase. We used this model to compare to experimental data from Schurch [1989]. We find that high levels of film compression lead transiently to large changes in adsorption rate, desorption rate and diffusion constant, consistent with what might expected if a selected purification of the interface was occurring leading to DPPC enrichment of the interface. The collapse of the surfactant film that occurs during compression leads to a significant elevation of surfactant concentration immediately underlying the interface, consistent with the formation of a subsurface deposit of surfactant.

E. P. Ingenito

Papers

Dynamic surface tension of surfactant TA: experiments and theory

Effect of high levels of film compression on surfactant transport