Scientific Center of Reconstructive and Restorative Surgery,

Irkutsk State Medical University,

Irkutsk Regional Clinical Consultory Diagnostic Center, 

Irkutsk, Russia

 

 

The morphologic signs of traumatic disease are highly multiform and, that’s the main thing, are non-specific. However they present not chaotic set of signs, but reflection of the complex response of the body to the injury [1]. Our previous study [2] of the laboratory chinchilla rabbits with multiple skeletal injuries found hyperemia and degenerative dystrophic changes in the internal organs – the common morphologic signs of acute and early periods of traumatic disease. In the same study we investigated the changes in activity of metabolism in the laboratory animals and concluded that the rabbits with multiple skeletal injuries demonstrated the adaptive strategy of tolerance (synonyms: hypobiosis, hypometabolism) [3].

For estimation of efficiency of tolerant adaptation to injuries the group was initiated that included the laboratory animals with multiple skeletal injuries which received adrenaline and dexamethasone – the drugs preventing adaptation of tolerant type. The prescription of adrenaline and dexamethasone allowed reducing expressiveness of hypometabolism in the rabbits with multiple skeletal injuries [4].

The present study was initiated for estimating influence of the directed correction of the adaptive response on posttraumatic changes in the internal organs in the laboratory animals.

Objective – to study the influence of dexamethasone and adrenaline on the morphometric indices in the heart, lungs, the liver and kidneys in rabbits after multiple orthopedic trauma.

 

MATERIALS AND METHODS

The examinations were carried out for 45 chinchilla rabbits (male) at the age of 6 months – one year, the weight of 3,100 (2,910; 3,750) g. The management, all manipulations and care for the animals were realized at the basis of the vivarium of the scientific department of experimental surgery in Scientific Center of Reconstructive and Restorative Surgery after approval from the ethical committee. The procedures corresponded to the Rules for Researches with Experimental Animals and the European Convention for Protection of Vertebral Animals for Experiments or Other Scientific Objectives.

The control group included 10 intact rabbits. The data from the control group were reviewed as normal. The retrieval of the internal organs (the heart, lungs, the liver and kidneys) was realized after euthanasia with intravenous administration of potassium chloride solution at the background of barbituric sedation. The morphometric examination of the drugs was realized at the basis of the department of pathologic morphology and cytology in Irkutsk Regional Clinical Consultative Diagnostic Center with use of the computer microscopic video system Quantimet 550IW (Leica, Great Britain) and the in-built package of the statistic morphometric programs Q-win for digital analysis of pathomorphological and cytological materials. The table 1 demonstrates the morphometric indices and the ways for their calculation.

22 animals in the main group #1 under general anesthesia received stabilization of the bones in the right forearm and the left leg by means of the rod device for external fixation including 2 subsystems with the following osteotomy in the corresponding segments in the middle one-third. The standard postsurgical treatment included intramuscular anesthesia with analgin, 400-500 mg per day for 5 days after surgery, antibiotic prevention with lincomycin, 50-70 mg/kg per day, and infusion therapy with glucose solution (5 %), 50-60 ml/kg per day for 3 days after surgery. For the animals with lethal outcomes within a week after surgery the retrieval of the internal organs was realized immediately after confirmation of biological death. In the survived rabbits the retrieval of the internal organs was performed 7 days after surgery in the same manner as in the control group.

For 13 rabbits in the main group #2 the model of multiple skeletal injuries was reproduced in the same manner as in the main group #1. However in the postsurgical period the animals in the main group #2 (parallel with standard treatment) also received parenteral adrenaline (2.5-3 µg/kg per day) and dexamethasone (4-6 mg/kg per day) for 3 days after injury. The retrieval of the samples of the internal organs in the main group #2 was realized in the same manner as in the main group #1.

The statistical preparation of the data was performed with the methods of descriptive statistics and comparison of the samples (Mann-Whitney test). The level of statistical significance was 0.05. The preparation of the data was realized with R program (version 2.13.1). The results of the study are presented as median, 25th and 75th percentiles.

 

RESULTS AND DISCUSSION

Liver. The relative square of necrosis in the laboratory animals after administration of adrenaline and dexamethasone showed statistically significant decrease by 3 %, cellular index decreased by 1.59 c.u., and the index of hepatocyte dystrophy demonstrated the evident tendency to decrease (Table 2). Therefore, comparison of the results of the morphometric examination in two main groups allow concluding about less expressive pattern of degenerative dystrophic changes in the rabbits’ liver in the main group #2.

Kidneys. The changes in the morphometric indices were less expressive in the kidneys in the laboratory animals of the main group #2 in comparison with the main group #1 (table 3). There were lower values of epithelial necrosis in the proximal tubules and lower vascular index in the rabbits in the main group #2. Moreover, if the difference in necrosis indices was only 3.25 %, then the intensity of renal hyperemia differed significantly (+86.7 % in the controls vs. +37.8 %).

Heart. Among 4 examined morphometric cardiac values the vascular index was only single value which had no statistically reliable difference in the main groups (table 4). Higher energetic capacity of the heart is supported by significantly higher contents of glycogen in the rabbits’ cardiomyocytes in the main group #2. Statistically lower values of necrosis square and the square of cardiomyocytes in the animals in the main group #2 testifies less intensity of injuries to cardiomyocytes and concurrent lung edema.

Lungs. The values of pulmonary vascular index and the square of alveoli did not demonstrate statistically significant differences in the main groups and showed equal intensity of posttraumatic hyperemia in the lungs with salvation of alveolar surface (table 5). At the same time, the significant increase in thickness of interalveolar septum (with high degree of statistical reliability) was noted in the main group #2 (+51.7 % in the controls vs. +24.6 % in the main group #1). It testified interstitial pulmonary edema.

In traumatic disease the expressiveness of secondary structural changes in the body depends on severity of traumatic shock and time after trauma [1, 5]. Whereas the characteristics of the injuries were homogenous in all laboratory animals, the total estimation of influence of adrenaline and dexamethasone on changes in the internal organs after multiple skeletal injuries should consider life span in the rabbits of the main groups in conditions of multiple skeletal injuries.

Within a week after injuries the mortality was 54.5 % in the main group #1 (12 dead animals among 22 ones), the life span after surgery was 7 (5; 7) days [3]. In the main group #2 at the background of prescribed adrenaline and dexamethasone the mortality increased to 92.3 % within a week after the injuries (12 dead animals among 13 ones), and the postsurgical life span decreased to 4 (3; 4) days [4]. Therefore, in the main group #2 traumatic disease was characterized with more severe course resulting in earlier unfavorable outcomes.

Such, at first glance, paradoxical results of the present study, i.e. more favorable morphologic background of the heart, the liver and kidneys in the animals with earlier death, open the way to settlement of the question about thanatogenesis in the group #2. The analysis of the results of morphometric examination of the internal organs in the laboratory animals in both groups supports the fact that the cause of death in the rabbits in the group #2 was secondary pulmonary injury resulting in morphologic changes in the picture of interstitial pulmonary edema, which is the structural equivalent of respiratory distress syndrome.

 

CONCLUSION

In the rabbits receiving dexamethasone and adrenaline in conditions of multiple skeletal injuries the statistically significant differences in morphometric values of the internal organs consisted in decrease in relative square of necrosis and cellular index in the liver, decreasing vascular index and proportion of the cells of proximal tubules with signs of necrosis in the kidneys, and also increasing glycogen in the heart. At the same time, the laboratory animals showed significant increase in thickness of interalveolar septum in the lungs that testified interstitial edema. The last conclusion is most important, because it indicates thanatogenesis in the rabbits in conditions of multiple skeletal trauma, while less intensity of dystrophic changes in the liver, the heart and the kidneys could be conditioned by decrease in posttraumatic life span in the laboratory animals in the main group #2.