An experimental study of skin flap associated with muscle: is muscle nourishment possible through the musculocutaneous perforators?

An experimental study was planned to examine whether the blood supply of muscle would be maintained by reverse flow from the cutaneous arteriolar microcirculatory system via the musculocutaneous perforators. A flap model containing both muscle and skin based on the inferior superficial epigastric vessels was designed with the blood supplied directly from the cutaneous arteriolar microcirculatory system. A total of 154 male Wistar Albino rats were divided into three groups. Group I included the standard vertical rectus abdominis musculocutaneous flap based on the superior deep epigastric vessels (N = 48). Group II included the acute cutaneous muscle flap (N = 53). Group III contained the delayed cutaneous muscle flap (N = 53). Skin flap survival area, muscle scintigraphy with technetium-99m-methoxy-isobutyl-isonitrile, microangiography, and histopathological examination of the flaps were conducted. The mean percentage of surviving skin paddle area was 96.4 +/- 5.2%, 84.9 +/- 21.6%, and 91.0 +/- 16.8% in groups I, II, and III respectively. There was no significant difference between groups. Microangiography revealed the blood flow from skin to muscle through the musculocutaneous perforators. The radioisotope uptake of the muscle flap was expressed as A percentage of the intact contralateral muscle. Mean uptake in group I was 90.1 +/- 4.9% immediately after flap elevation, 62.5 +/- 13.5% on day 2, and 88.3 +/- 12.0% on day 7. These values were 53.7 +/- 7.1%, 63.6 +/- 14.1%, and 89.2 +/- 18.1% in group II, and 64 +/- 7.8%, 75.5 +/- 9.8%, and 92.8 +/- 40.1% in group III. Radioisotope uptake in group I was significantly higher than groups II and III immediately after flap elevation (p < 0.05, analysis of variance), whereas there was no significant difference on days 2 and 7. Histopathological examination revealed surviving muscle tissue without marked atrophy. There was no marked difference between groups histopathologically. These results indicate that muscle tissue may survive by reverse flow through the musculocutaneous perforators when elevated with an axial skin flap.     

Does focal destruction of the thoracic aorta wall by Staphylococcus aureus lead to the development of infected aneurysms? An experimental study

Objective: The infrequency of infected aneurysms suggests that either infection of segments of the aortic wall is uncommon, or that infections do not always lead top infected aneurysm formation. The purpose of the study was to determine whether focal Staphylococcus aureus infection of aortic wall segments leads consistently to the development of infected aneurysms and to evaluate the segments in which infection did not lead to the infected aneurysm formation. Methods: Twenty pigs were inoculated with 0.1 ml of a Staphylococcus aureus inoculum in three segments of the thoracic aorta wall (study group). In another 10 pigs, 0.1 ml of saline solution was injected in three segments of the thoracic aorta wall (control group). Study group: histological abnormalities and bacterial culture of the inoculation sites were evaluated at 10 days (n=5 pigs), 30 days (n=5 pigs), and 90 days (n=10 pigs). Control group: histological abnormalities were evaluated at 10 days (n=5 pigs) and 90 days (n=5 pigs). Results: Study group: infected aneurysms developed in only two animals killed at 30 days. At 90 days, destruction of the elastic tissue, scar tissue and neointima formation were found in all the aortic segments studied. Control group: no significant changes were found in any of the segments evaluated. Conclusion: In our experimental model, acute local infection by S. aureus caused the development of infected aortic aneurysm in only 10% of the animals. In the remaining 90%, healing of the site of infection followed resolution of the infection.     

Does the length of the interposed segment in the Henley procedure influence duodenogastric reflux? An experimental study

This study assesses duodenogastric reflux (DGR) using 99mTechnetium-diisopropyl iminodiacetic acid in unoperated dogs and in dogs 28 days after a Billroth II gastrectomy and 28 days after the Henley procedure. Fourteen mongrel dogs were divided randomly into two groups of seven each, according to the length of the interposed jejunal segment used (Group A 10 cm; Group B, 20 cm). All dogs were subjected to a Billroth II gastrectomy, followed by the Henley procedure 30 days later. In Group A, DGR was significantly lower in the preoperative period (median, 0.0%; range, 0.0-0.02%) than after gastrectomy (median, 0.13%; range, 0.08-0.70%) and the Henley procedure (median, 0.12%; range, 0.06-0.22%), but did not differ significantly after gastrectomy and jejunal interposition. In Group B, DGR was significantly higher after gastrectomy (median, 0.15%; range, 0.10-0.64%) than in the preoperative period (median, 0.00%; range, 0.00-0.09%) or than after the Henley procedure (median, 0.00%; range, 0.00-0.7%). DGR did not differ significantly between the preoperative period and after Henley procedure. After jejunal interposition, DGR was significantly higher in Group A than in Group B. The Henley procedure is effective in preventing DGR when the interposed segment is 20 cm in length.     

Does estrogen alter the mechanical properties of the anterior cruciate ligament? An experimental study in rabbits

BACKGROUND: It is well known that anterior cruciate ligament (ACL) injuries are commoner in female athletes. Accordingly, we hypothesized that serum estrogen may play some role in this sex difference. We evaluated the relationship between serum estrogen levels and the mechanical properties of the ACL in rabbits. ANIMALS AND METHODS: In 40 ovariectomized rabbits, the serum estrogen levels (SEL) were controlled by intramuscular injection of 17beta-estradiol. The mean SEL in each rabbit was defined as the average of 5 determinations done at 1, 2, 3, 4 and 5 weeks after ovariectomy. The animals were divided into 4 groups according to the dose of estradiol administered (low, medium, high and control: L, M, H and C, respectively) and into 2 groups according to the mean SEL (high-SEL group and low-SEL group). The medial portions of ACL attached to both femur and tibia harvested at 5 weeks after ovariectomy were examined mechanically. RESULTS: The mean serum estrogen levels in groups C, L, M and H were 37, 50, 60 and 231 pg/mL. Statistically significant differences in the mean serum estrogen levels were seen among the 4 groups, except between groups L and M. Statistically significant differences were found between groups M and H in both the ultimate tensile stress and linear stiffness. In the comparison between 2 groups using the mean SEL value, both ultimate tensile stress and linear stiffness were lower in the high-SEL group. In all animals, a positive correlation was found between ultimate tensile stress and linear stiffness. INTERPRETATION: Our findings suggest that high SEL might be one of the factors in the multifactorial pathogenesis of ACL rupture.     

Does estrogen alter the mechanical properties of the anterior cruciate ligament?: An experimental study in rabbits

Background?It is well known that anterior cruciate ligament (ACL) injuries are commoner in female athletes. Accordingly, we hypothesized that serum estrogen may play some role in this sex difference. We evaluated the relationship between serum estrogen levels and the mechanical properties of the ACL in rabbits.

Animals and methods?In 40 ovariectomized rabbits, the serum estrogen levels (SEL) were controlled by intramuscular injection of 17β-estradiol. The mean SEL in each rabbit was defined as the average of 5 determinations done at 1, 2, 3, 4 and 5 weeks after ovariectomy. The animals were divided into 4 groups according to the dose of estradiol administered (low, medium, high and control: L, M, H and C, respectively) and into 2 groups according to the mean SEL (high-SEL group and low-SEL group). The medial portions of ACL attached to both femur and tibia harvested at 5 weeks after ovariectomy were examined mechanically.

Results?The mean serum estrogen levels in groups C, L, M and H were 37, 50, 60 and 231 pg/mL. Statistically significant differences in the mean serum estrogen levels were seen among the 4 groups, except between groups L and M. Statistically significant differences were found between groups M and H in both the ultimate tensile stress and linear stiffness. In the comparison between 2 groups using the mean SEL value, both ultimate tensile stress and linear stiffness were lower in the high-SEL group. In all animals, a positive correlation was found between ultimate tensile stress and linear stiffness.

Interpretation?Our findings suggest that high SEL might be one of the factors in the multifactorial pathogenesis of ACL rupture.     

Does mesh implantation affect the spermatic cord structures after inguinal hernia surgery? An experimental study in rats

BACKGROUND: Inguinal hernia repair is the most common operation in general surgery. Prosthetic reinforcement of the inguinal area with polypropylene mesh has increased dramatically in the last decade. The aim of this study was to evaluate how different types of mesh affect the spermatic cord structures. METHODS: Thirty rats were divided into three groups. The spermatic cord was dissected free and a conventional suture repair was performed in group I, an operation mimicking the Lichtenstein operation with a heavyweight polypropylene mesh in group II and the same operation using large pore, lightweighted polypropylene/polyglactin composite mesh in group III. A vasography was performed after 90 days. The cross-sectional area of the vas deferens and s-testosterone from the spermatic vein were measured using the contralateral side as control. Light microscopy of the inguinal canal was performed and inflammation and fibrosis were graded. RESULTS: Vasography revealed patent vas deferens in all animals. In group III, there was a lower s-testosterone in the spermatic vein and a reduced cross-sectional area of the vas deferens on the operated compared to the control side. However, there was no difference in the other groups and there was no significant difference in s-testosterone levels between the groups. There was significantly more inflammation and fibrosis after mesh repair compared to suture repair, but there was no difference between the two mesh groups. Unexpectedly, polyglactin fibres were still seen in specimens in group III after 90 days. CONCLUSION: In conclusion, the only effect on the spermatic cord structures in a rat model is seen as an impaired s-testosterone production and a reduced cross-sectional area of the vas deferens after use of a low-weight composite mesh compared to the control side. No difference in inflammation or fibrosis was found between heavyweight polypropylene mesh and low-weight composite mesh.     

Does the inter-osseous membrane fascial dysfunction exist ? An observational study comparing palpation to ultrasound measurements

BackgroundThere is a lack of evidence to support a correspondence between osteopathic palpation and anatomical findings. The concept of dysfunction could be defined using more accurate words when describing palpatory findings if they could be explained by objective measurements. The forearm Interosseous Membrane (IOM) is a fascia often evaluated by osteopaths, searching for Fascial Dysfunction (FD). We measured IOM physical characteristics, such as elasticity and thickness, with ultrasound (US) and then compared it with osteopaths’ FD assessment.MethodsHealthy subjects were recruited and their forearms were marked every centimeter. At every mark, 3 registered osteopaths assessed the potential FD (none, moderate or strong). Assessments were compared to the IOM elasticity and thickness measured by US. A mixed effect model was used to analyse the link between thickness and FD and a chi-2 test for the link between elasticity and FD.Result41 subjects were included. Mean age was 28.1, 46% were men. The average IOM length was 13.0 cm (±1.5), the average thickness was 1.29 (±0.41). The mixed model found a strong correlation between the grade of FD and the IOM thickness for all three osteopaths (p < 0.01). Moreover, correlations were found between thickness and elasticity of the IOM (p < 0.001).ConclusionManual evaluation of FD seems to be correlated to physical properties of the IOM. Our results suggest that the forearm IOM is thicker at FD locations. This study needs replications on several anatomical areas and on the IOM of symptomatic subjects to confirm these findings. Moreover, research could focus on tissue changes after osteopathic treatment.     

Does nitrous oxide labor analgesia influence the pattern of neuraxial analgesia usage? An impact study at an academic medical center

Study objectiveTo compare the rate of epidural use before and after the implementation of nitrous oxide (N₂O).DesignData were obtained from a nursing database of N₂O usage and our obstetric anesthesia database. We compared 8 months before and 8 months after the introduction of N₂O. It was available 24 h/d, 7 d/wk, consistent with neuraxial analgesia availability. Epidural utilization before and after introduction of N₂O was compared using χ² analysis.SettingLabor and delivery floor.Main resultsTotal number of births over the study period was 8539: 4315 pre-N2O and 4224 post-N₂O. The rate of epidural usage was 77% pre-N₂O and 74% after N₂O (P= not significant, χ²). A total of 762 patients used N₂O. Monthly analysis showed no change in pattern of neuraxial analgesia use in post-N₂O period compared with the pre-N₂O period.ConclusionThe introduction of N₂O for labor analgesia was not associated with any change in our rate of labor epidural utilization. Under the conditions of our study, these results suggest that N₂O does not discourage neuraxial use for labor pain relief.     

Does the method of expression of venous blood affect ischaemia/reperfusion damage in tourniquet use? An experimental study on rabbits

The aim of this study was to compare the ischaemia and reperfusion phases of two tourniquet application models (Group 1: expressing the blood by a sterile rubber bandage and Group 2: elevation of the limb for several minutes) using an analysis of ischaemia/reperfusion parameters and blood pH.     

Can the ischemia-reperfusion syndrome in transplanted kidneys procured from non-heart-beating donors be influenced by adding selenium into the reperfusion solution? An experimental study

The ischemic-reperfusion syndrome significantly influences the function of a kidney transplanted from a non-heart-beating donor (NHBD). The animal model of a NHBD was used to monitor the influence of exogenous addition of selenium into the reperfusion solution (HTK, Custodiol) with respect to the formation of free oxygen radicals at 0 to 120 minutes after the NHBD transplantation. This maneuvers produced a statistically significant decrease in malondialdehyde concentration, an indicator of free oxygen radicals in the venous blood of the transplanted kidney. The augmentation of the antioxidative capacity of the preservation solution might be a possible route to improve the function of kidneys transplanted from NHBDs.     

Can ischemia-reperfusion syndrome in transplanted kidneys procured from non-heart-beating donors be influenced by adding selenium into the reperfusion solution? An experimental study

Ischemia-reperfusion syndrome significantly influences the function of a kidney transplanted from a non-heart-beating donor (NHBD). An animal model of NHBD was used to monitor the influence of the exogenous addition of selenium in the perfusion solution (HTK, Custodiol) on the generation of free oxygen radicals between 0 and 120 minutes after transplantation of the NHBD organ. During this interval, the malondialdehyde concentration, an indicator of free oxygen radicals in the venous blood of the transplanted kidney, significantly decreased. The augmentation of the anti-oxidant capacity of the preservation solution might represent a possible improvement in the function of kidneys transplanted from NHBDs.     

Is maintained cranial hypothermia the only factor leading to improved outcome after retrograde cerebral perfusion? An experimental study with a chronic porcine model

BACKGROUND: Previous studies have shown that retrograde cerebral perfusion can improve neurologic outcome after prolonged hypothermic circulatory arrest. Here we have compared two temperatures of retrograde cerebral perfusion (15 degrees C and 25 degrees C) with hypothermic circulatory arrest at systemic hypothermia of 25 degrees C to clarify whether the possible benefit of retrograde cerebral perfusion may only be due to improved cooling effect. METHODS: Eighteen pigs (23-27 kg) were randomly assigned to undergo 15 degrees C retrograde cerebral perfusion at systemic hypothermia of 25 degrees C, 25 degrees C retrograde cerebral perfusion at 25 degrees C systemic hypothermia, or hypothermic circulatory arrest at 25 degrees C for 40 minutes. Flow was adjusted to maintain superior vena cava pressure at 20 mm Hg during retrograde cerebral perfusion. Hemodynamic, electrophysiologic, metabolic, and temperature monitoring were performed until 4 hours after the start of rewarming. Daily behavioral assessment was done until death or until the animals were killed on day 7. Histopathologic analysis of the brain was carried out on all animals. RESULTS: Epidural temperatures were lower in the 15 degrees C retrograde cerebral perfusion group during the intervention (P <.05). In the 15 degrees C retrograde cerebral perfusion group, 4 (67%) of 6 animals survived for 7 days compared with 3 (50%) of 6 in both the 25 degrees C retrograde cerebral perfusion and hypothermic circulatory arrest groups. The median total histopathologic score was 5 in the 15 degrees C retrograde cerebral perfusion group and 7 in the 25 degrees C retrograde cerebral perfusion group (P =.04). CONCLUSIONS: These findings suggest that enhanced cranial hypothermia is the major beneficial factor of retrograde cerebral perfusion when careful attention is paid to its implementation.