No protection in sheep by high-dose methylprednisolone against pulmonary microvascular injury following trauma.
The osmotic reflection coefficient (sigma) of the pulmonary microvessels in sheep was estimated after a preparative trauma, and the effect of a single, high (30 mg kg -1 b.w.) dose of methylprednisolone (MP) (n = 7) compared to a dose of normal saline (S) (n = 8) was evaluated. After bilateral thoracotomies for lung lymph cannulation and placement of a balloon catheter in the left atrium, the animals were followed during anesthesia for 1 hour. Left atrial pressure (Pla) was then increased and 2 levels of filtration-independent lymph to plasma protein concentration ratio (L/P) were recorded. After the operation leukocyte and platelet counts in both groups decreased significantly. Lung lymph flow (QL) increased during the first hour without hemodynamic changes, whereas L/P decreased in the MP group but was unaffected in the S group. Partial pressure of oxygen (PaO2) was spontaneously improved postoperatively in the MP group but remained unchanged in the S group. The 2 levels of filtration-independent L/P were reached at Pla 28.7 +/- 2.8 and 34.3 +/- 1.6 mm Hg in the MP group and 25.6 +/- 2.2 and 31.3 +/- 1.3 mm Hg in the S group. QL increased by 500 +/- 80% (n = 7) and 930 +/- 210% (n = 7) at the 2 levels of increased Pla with unchanged L/P at 0.44 +/- 0.03 and 0.46 +/- 0.04, respectively, in the MP group. Corresponding values in the S group were a 590 +/- 160 (n = 5) and 730 +/- 180% (n = 3) increase in QL with L/P 0.41 +/- 0.02 and 0.40 +/- 0.03, respectively. sigma in the MP group was 0.54 +/- 0.04, and sigma in the S group was 0.62 +/- 0.02, which was not significantly different. Thus pretreatment with MP did not prevent the development of a permeability lesion following surgical pulmonary trauma, but an early minor protective effect of MP could not be ruled out.
D000818:Animals; D001808:Blood Vessels / Q000293:injuries; D006439:Hemodynamics / Q000187:drug effects; D008168:Lung / Q000098:blood supply* / Q000187:drug effects; D055370:Lung Injury; D008176:Lung Volume Measurements; D008775:Methylprednisolone / Q000008:administration & dosage / Q000494:pharmacology*; D008833:Microcirculation / Q000187:drug effects*; D009994:Osmolar Concentration; D011897:Random Allocation; D012756:Sheep
D008775:Methylprednisolone