Evolution of the inflammatory and fibroproliferative responses during resolution and repair after ventilator-induced lung injury in the rat

Background: The time course and mechanisms of resolution and repair, and the potential for fibrosis following ventilation-induced lung injury (VILI), are unclear. We sought to examine the pattern of inflammation, injury, repair, and fibrosis following VILI. Methods: Sixty anesthetized rats were subject to high-stretch; low-stretch, or sham ventilation, and randomly allocated to undergo periods of recovery of 6, 24, 48, and 96 h, and 7 and 14 days. Animals were then reanesthetized, and the extent of lung injury, inflammation, and repair determined. Results: No injury was seen following low-stretch or sham ventilation. VILI caused severe lung injury, maximal at 24 h, but largely resolved by 96 h. Arterial oxygen tension decreased from a mean (SD) of 144.8 (4.1) mmHg to 96.2 (10.3) mmHg 6 h after VILI, before gradually recovering to 131.2 (14.3) mmHg at 96 h. VILI induced an early neutrophilic alveolitis and a later lymphocytic alveolitis, followed by a monocyte/macrophage infiltration. Alveolar tumor necrosis factor-alpha, interleukin-1 beta, and transforming growth factor-beta 1 concentrations peaked at 6 h and returned to baseline within 24 h, while interleukin-10 remained increased for 48 h. VILI generated a marked but transient fibroproliferative response, which restored normal lung architecture. There was no evidence of fibrosis at 7 and 14 days. Conclusions: High-stretch ventilation caused severe lung injury, activating a transient inflammatory and fibroproliferative repair response, which restored normal lung architecture without evidence of fibrosis

Evolution of the inflammatory and fibroproliferative responses during resolution and repair after ventilator-induced lung injury in the rat

Background: The time course and mechanisms of resolution and repair, and the potential for fibrosis following ventilation-induced lung injury (VILI), are unclear. We sought to examine the pattern of inflammation, injury, repair, and fibrosis following VILI. Methods: Sixty anesthetized rats were subject to high-stretch; low-stretch, or sham ventilation, and randomly allocated to undergo periods of recovery of 6, 24, 48, and 96 h, and 7 and 14 days. Animals were then reanesthetized, and the extent of lung injury, inflammation, and repair determined. Results: No injury was seen following low-stretch or sham ventilation. VILI caused severe lung injury, maximal at 24 h, but largely resolved by 96 h. Arterial oxygen tension decreased from a mean (SD) of 144.8 (4.1) mmHg to 96.2 (10.3) mmHg 6 h after VILI, before gradually recovering to 131.2 (14.3) mmHg at 96 h. VILI induced an early neutrophilic alveolitis and a later lymphocytic alveolitis, followed by a monocyte/macrophage infiltration. Alveolar tumor necrosis factor-alpha, interleukin-1 beta, and transforming growth factor-beta 1 concentrations peaked at 6 h and returned to baseline within 24 h, while interleukin-10 remained increased for 48 h. VILI generated a marked but transient fibroproliferative response, which restored normal lung architecture. There was no evidence of fibrosis at 7 and 14 days. Conclusions: High-stretch ventilation caused severe lung injury, activating a transient inflammatory and fibroproliferative repair response, which restored normal lung architecture without evidence of fibrosis

Inter-Rater Reliability of The Modified Radiographic Union Score for Diaphyseal Tibial (mRUST) Fractures with Bone Defects

OBJECTIVES:To evaluate inter-rater reliability of the modified Radiographic Union Score for Tibial (mRUST) fractures among patients with open, diaphyseal tibia fractures with a bone defect treated with intramedullary nails (IMNs), plates, or definitive external fixation (ex-fix). DESIGN:Retrospective cohort study. SETTING:Fifteen-level one civilian trauma centers; 2 military treatment facilities. PATIENTS/PARTICIPANTS:Patients ≥18 years old with open, diaphyseal tibia fractures with a bone defect ≥1 cm surgically treated between 2007 and 2012. INTERVENTION:Three of 6 orthopedic traumatologists reviewed and applied mRUST scoring criteria to radiographs from the last clinical visit within 13 months of injury. MAIN OUTCOME MEASUREMENTS:Inter-rater reliability was assessed using Krippendorff's alpha (KA) statistic; intraclass correlation coefficient (ICC) is presented for comparison with previous publications. RESULTS:Two hundred thirteen patients met inclusion criteria including 115 IMNs, 24 plates, 29 ex-fixes, and 45 cases that no longer had instrumentation at evaluation. All reviewers agreed on the pattern of scoreable cortices for 90.4% of IMNs, 88.9% of those without instrumentation, 44.8% of rings, and 20.8% of plates. Thirty-one (15%) cases, primarily plates and ex-fixes, did not contribute to KA and ICC estimates because <2 raters scored all cortices. The overall KA for the 85% that could be analyzed was 0.64 (ICC 0.71). For IMNs, plates, ex-fixes, and no instrumentation, KA (ICC) was 0.65 (0.75), 0.88 (0.90), 0.47 (0.62), and 0.48 (0.57), respectively. CONCLUSIONS:In tibia fractures with bone defects, the mRUST seems similarly reliable to previous work in patients treated with IMN but is less reliable in those with plates or ex-fixes, or after removal of instrumentation