Surfactant administration prior to one lung ventilation: physiological and inflammatory correlates in a piglet model

Abstract

Objectives: To test the hypothesis that surfactant, when given prophylactically during one lung ventilation (OLV), improves physiological stability and reduces inflammation.

Methods: Prospective controlled animal study. After 30 min of mechanical ventilation, surfactant was administered to the left lung of the treatment group. Right lung mechanical ventilation continued for 3 hr, after which the left lung was unblocked. Bilateral mechanical ventilation was continued for 30 min thereafter. Physiological parameters and biomarkers of inflammation in plasma, lung tissue homogenates, and bronchoalveolar lavage (BAL) were measured.

Measurements and main results: Oxygenation improved in the surfactant group, reaching statistical significance at 3 hr of OLV and again after 30 min of bilateral mechanical ventilation following the OLV. Plasma levels of interleukin (IL)-1 β, IL-6, and tumor necrosis factor (TNF)-α showed a trend for reduction. The lung homogenates from the ventilated lungs had significantly lower levels of IL-1 β (P < 0.01) and IL-6 (P < 0.01). The BAL specimen showed an overall reduction in the cytokine levels; IL-1 β was significantly lower in the ventilated lungs (P < 0.01).

Conclusions: Surfactant administration improves oxygenation and decreases inflammation, as evidenced by a decrease in several inflammatory cytokines both in the plasma and lungs of a piglet model of OLV.

Figure 1

Surfactant (SF)-group and control-group PaO₂ over time. There was an improvement in oxygenation as a function of time in the SF group, which reached significance at three hours of one lung ventilation (OLV) and again at the end of the experiment when compared with the control group. Overall, the P value for comparing means of two groups after age and weight adjustment was 0.15.

Figure 2

Compliance over time for surfactant (SF) and control group. The P value for comparing means of two groups after age and weight adjustment was 0.16. Although this P value is not significant, the trend favored the SF group.

Figure 3

Plasma levels of (A) interleukin (IL)-1 β, (B) IL-6, and (C) tumor necrosis factor (TNF)-α shown as a function of group and time after log 10 transformation. As shown, there was a trend for a reduction of mediators in the surfactant compared with the control group over time. The P values for comparing means of two groups after age and weight adjustment are shown in text. There is no significant difference between baseline means of two groups for log 10 transformed values of IL-1 β and TNF-α (P > 0.80), and there is no difference between the baseline means of the two groups for IL-6. All of baseline values for IL-6 were 0. *Represents the points at which mean cytokine levels were significantly different.

Figure 4

The lung homogenates, (A) interleukin (IL)-1 β, (B) IL-6, and (C) tumor necrosis factor (TNF)-α, from the ventilated lungs in the surfactant (SF) group had significantly lower levels of IL-6 (P < 0.01) and IL-1 β (P < 0.01); TNF-α was not significantly different between groups. Analysis by Mann–Whitney U-test. Median, range, and P values are represented.

Figure 5

Bronchioalveolar lavage specimens obtained from both lungs are illustrated; (A) interleukin (IL)-1 β, (B) IL-6, and (C) tumor necrosis factor (TNF)-α. Interleukin-1β from the ventilated lungs was significantly lower in the surfactant group compared with the control group (P < 0.01). Analysis by Mann–Whitney U-test. Median, range, and P values are represented.

Figure 6

Haematoxylin and eosin staining of lung tissue harvested at completion of the OLV experiment. Lung histology specimens from the left lung of the control and surfactant (SF) group are shown alongside right lungs of the control and SF group (the specimens were obtained from the base sections of both sides).