Lung Function in Prematurely Delivered Rabbits Treated with a Synthetic Surfactant

Abstract

We treated prematurely delivered rabbit pups with the synthetic surfactant that has been named Exosurf. By weight, Exosurf is 61.8% dipalmitoylphosphatidylcholine, 6.8% hexadecanol, 4.6% tyloxapol, and 26.7% NaCl. This simple mixture, suspended at 15 mg lipid X ml-1 water, has appropriate in vitro characteristics for a lung surfactant substitute. As determined by static pressure volume relationships performed after 30 min ventilation, lungs treated with Exosurf accepted significantly more gas at maximal inflation (36 versus 15 ml X kg-1 body weight) and had significantly greater volumes during deflation that did saline-treated control lungs; lungs treated with natural rabbit surfactant (SAM) had significantly larger volumes at maximal inflation (65 versus 35 ml X kg-1) and during deflation than did the Exosurf-treated lungs. After 30 min of ventilation with oxygen and fixation at 10 cm H2O pressure, the ratio of air space to tissue space was determined by a point-counting technique, and mean linear intercepts were measured for air spaces. Exosurf-treated lungs were intermediate between SAM and saline-treated lungs in both measurements. With positive pressure ventilation to maintain a tidal volume of 6.5 to 7.5 ml X kg-1, total compliance was significantly greater and inspiratory pressure significantly lower in both SAM- and Exosurf-treated animals than in saline-treated control animals, although the lungs of the SAM-treated animals were more compliant than the lungs of animals treated with Exosurf. During the first minute of positive pressure ventilation, lungs treated with SAM or Exosurf expanded equally rapidly, both expanding more rapidly than the saline-treated lungs.(ABSTRACT TRUNCATED AT 250 WORDS)

Surfactant Improves Gas Mixing and Alveolar Ventilation in Preterm Lambs

“…In animal studies, several investigators have shown an improvement in Cdyn after surfactant treatment in immature lung disease (4)(5)(6)(7)(8). In our study, there were also differences in Cdyn between surfactanttreated and untreated animals, with significantly higher Cdyn in the treated group.…”

“…The techniques used in this study should also be useful to evaluate lung function in preterm human infants after specific adaptation of the equipment size. (1)(2)(3)(4)(5)(6)(7)(8), clinical course, and outcome (9-1 1). It has also been suggested that prophylactic surfactant treatment before initiation of spontaneous or mechanical ventilation is the best way to prevent injury to distal conducting airways, i.e.…”

The Physiologic Effects of Surfactant Treatment on Gas Exchange in Newborn Premature Infants with Hyaline Membrane Disease

“…These differences in response between BS and SS may reflect differences in physicochemical properties between the two surfactant preparations. When used to treat newborn premature rabbit pups before air breathing, SS had a less intense beneficial effect on lung mechanical properties than natural surface-active material ( 16). This difference was attributed to the absence of surfactant apoproteins in SS and to properties such as adsorption rate and spreading.…”

Targeted delivery of liquid microvolumes into the lung

“…This liquid plug instillation approach has been an effective delivery method for surfactant replacement therapy, in which microliters of pharmaceutical pulmonary surfactant are instilled into the lungs to treat respiratory distress syndrome (13)(14)(15)(16). Although the plug instillation approach is rather invasive and more suitable for treatment in the inpatient setting, improved therapeutic effect could be achieved with minimal systemic absorption and more precise determination of the effective drug dose (12).…”