Reply by the Authors of the Original Article

A Comment on the Pulmonary Contusion Model

We read the comment and the related article of Yucel et al.[1] They studied an experimental blunt chest trauma model and claimed that the weight and height used in our experimental model was too much for rats.

In our study, we conducted an experimental study to evaluate the effect of dimethylsulfoxide (DMSO) and dexamethasone to lung injury occurred secondary to blunt chest trauma in rat model. Therefore, we had to use a previously proven experimental model. We used modified version of the model of Raghavendran et al.[2] Raghavendran used 0.3 kg weight from different height to get different impact energies in between 1.80 and 2.70 J (E = m × G  × h). They reported that the impact energy should not exceed 2.45 J to prevent fatal complications. However, they performed the experiments on a platform with a cardioprotective sheet to have bilateral contusion. Because we aimed to get unilateral contusion model, we dropped the weight on the right hemithorax to prevent cardiac complications. We dropped 0.5 kg weight from 40 cm height to get 1.96-J impact energy (E = 0.5 × 9.8 × 0.4 = 1.96 J), which was reported as the most appropriate energy to get lung injury with lower mortality by Ozel et al.[3]

We have already had a control group in our study. We did not perform chest trauma in control group animals and compared the trauma group (Sham) with that control group. Macroscopic and histopathological findings revealed significant difference in SG compared with CG revealing that our model was able to cause lung injury. Therefore, we think that first part of our study was appropriate with reliable results. All these data were given in the manuscript in detail.

Additionally, we read the article given in the commentary.[1] We realized that the calculated impact energy in Table 1 was less than the total energy obtained by E = m × g × h formula and they should be 0.40 J for 40 g, 0.68 J for 70 g, and 0.98 J for 100 g when dropped from 1 m height. Therefore, we suggest that their experimental model generates less energy than the study they cited.[2] [3] However, experimental model for blunt thoracic trauma can be obtained with less impact energy; we preferred the most common experimental model to compare our results with the previous studies.

• References

• 1 Yücel O, Genç O, Özcan A , et al. The blunt thoracic trauma model on rat lungs: an experimental study. Gulhane Med J 2008; 50 (4) 249-252
• 2 Raghavendran K, Davidson BA, Helinski JD , et al. A rat model for isolated bilateral lung contusion from blunt chest trauma. Anesth Analg 2005; 101 (5) 1482-1489
• 3 Özel ŞK, Özel HB, Colakoğlu N, Ilhan N, Arslan N, Ozan E. Protective effect of the thoracic cage on parenchyma in response to trauma direction in blunt thoracic trauma: an experimental study. Ulus Travma Acil Cerrahi Derg 2010; 16 (4) 287-292