Internal fixator vs external fixator in the management of unstable pelvic ring injuries:A prospective comparative cohort study

BACKGROUND Reconstruction of the pelvic ring anatomy in unstable anterior pelvic ring injuries is a significant step to reduce the mortality rate associated with these injuries efficiently.There is a debate on using either an anterior subcutaneous pelvis internal fixator(INFIX)or an anterior supra-acetabular external fixator(EXFIX)to manage an unstable anterior pelvic ring fracture.AIM To compare the functional and radiological outcomes and complications of INFIX vs EXFIX in managing unstable pelvic ring injuries.METHODS A prospective cohort study included 54 patients with unstable pelvic ring fractures.The patients were divided into two groups;the INFIX group,in which 30 cases were fixed by INFIX,and the EXFIX group,in which 24 patients were treated by EXFIX.The average age in the EXFIX group was 31.17 years(16-57 years),while in the INFIX group,it was 34.5 years(17-53 years).The study included 20(66.7%)males and 10(33.3%)females in the INFIX group and 10(41.7%)males and 14(58.3%)females in the EXFIX group.The radiological outcomes were evaluated using Matta and Tornetta's score,and the functional outcomes using the Majeed score.RESULTS The results revealed a statistically significant difference between both groups(P=0.013)regarding radiological outcomes,according to Matta and Tornetta's score in favor of the INFIX group.Sitting,standing,and walking abilities were measured at a 3-mo follow-up visit using Majeed score modules.It was significantly better among the INFIX group than the EXFIX group in all three modules.At the final follow-up,both groups had no statistically significant difference according to the Majeed score;92.35 in the INFIX group and 90.99 in the EXFIX group(P=0.513).A lower surgical site infection rate was noticed in the INFIX group(P=0.007).CONCLUSION Anterior subcutaneous pelvis INFIX is associated with better radiological outcomes and a lower infection rate than anterior supra-acetabular EXFIX in managing patients with unstable anterior pelvic ring fractures.

Simulation and calculation of internal faults in long-stator linear synchronous motor based on winding function theory

To guarantee the safety of the high speed maglev train system, a novel model based on the winding function theory is proposed for the long-stator linear synchronous motor（LSM）, which is suitable for the real-time calculation of the running state. The accurate coupled mathematical models under different internal fault conditions of the LSM are derived based on the normal model. Then the fault currents and electromagnetic forces are simulated and calculated for the major potential internal faults of the LSM, such as the single-phase short circuit, the phase-phase short circuit and the single-phase open circuit. The characteristic curve between the electromagnetic force and the armature current of the LSM, which is compared with the results from the finite element method, proves the validation of the proposed method. The fault rule is determined and the proposed analytical model also shows its feasibility in the fast fault diagnosis through the comparison of the simulation results of currents and electromagnetic forces under different internal fault types and short circuit ratios.

Failure Statistics Analysis Based on Bayesian Theory: A Study of FPSO Internal Turret Leakage

The load and corrosion caused by the harsh marine environment lead to the severe degradation of offshore equipment and to their compromised security and reliability. In the quantitative risk analysis, the failure models are difficult to establish through traditional statistical methods. Hence, the calculation of the occurrence probability of small sample events is often met with great uncertainty. In this study, the Bayesian statistical method is implemented to analyze the oil and gas leakages of FPSO internal turret, which is a typical small sample risk but could lead to severe losses.According to the corresponding failure mechanism, two Bayesian statistical models using the Weibull distribution and logarithmic normal distribution as the population distribution are established, and the posterior distribution of the corresponding parameters is calculated. The optimal Bayesian statistical model is determined according to the Bayesian information criterion and Akaike criterion. On the basis of the determined optimal model, the corresponding reliability index is solved to provide basic data for the subsequent risk assessments of FPSO systems.

Research on adsorption mechanism of wall climbing robots based on internally balanced theory

The internally balanced theory proposed by the Japanese researchers,solved the contradiction between adsorption ability and moving capability of the permanent magnetic adsorption mechanism.However,it still has some problems when applied to wall climbing robots.This paper analyzes and improves this theory,and the improved internally balanced theory satisfies the requirements of the adsorption mechanism significantly.Finally,a practical prototype is proposed based on this method,and both the analysis using ANSYS and the experiment results justify the design validity.

Ordered Rate Constitutive Theories for Non-Classical Thermoviscoelastic Fluids with Internal Rotation Rates

The paper presents constitutive theories for non-classical thermoviscoelastic fluids with dissipation and memory using a thermodynamic framework based on entirety of velocity gradient tensor. Thus, the conservation and the balance laws used in this work incorporate symmetric as well as antisymmetric part of the velocity gradient tensor. The constitutive theories derived here hold in coand contra-variant bases as well as in Jaumann rates and are derived using convected time derivatives of Green’s and Almansi strain tensors as well as the Cauchy stress tensor and its convected time derivatives in appropriate bases. The constitutive theories are presented in the absence as well as in the presence of the balance of moment of moments as balance law. It is shown that the dissipation mechanism and the fading memory in such fluids are due to stress rates as well as moment rates and their conjugates. The material coefficients are derived for the general forms of the constitutive theories based on integrity. Simplified linear (or quasi-linear) forms of the constitutive theories are also presented. Maxwell, Oldroyd-B and Giesekus constitutive models for non-classical thermoviscoelastic fluids are derived and are compared with those derived based on classical continuum mechanics. Both, compressible and incompressible thermoviscoelastic fluids are considered.

Clinical efficacy of integral theory–guided laparoscopic integral pelvic floor/ligament repair in the treatment of internal rectal prolapse in females

BACKGROUND Internal rectal prolapse(IRP)is one of the most common causes of obstructive constipation.The incidence of IRP in women is approximately three times that in men.IRP is mainly treated by surgery,which can be divided into two categories:Abdominal procedures and perineal procedures.This study offers a better procedure for the treatment of IRP.AIM To compare the clinical efficacy of laparoscopic integral pelvic floor/ligament repair(IPFLR)combined with a procedure for prolapse and hemorrhoids(PPH)and the laparoscopic IPFLR alone in the treatment of IRP in women.METHODS This study collected the clinical data of 130 female patients with IRP who underwent surgery from January 2012 to October 2014.The patients were divided into groups A and B.Group A had 63 patients who underwent laparoscopic IPFLR alone,and group B had 67 patients who underwent the laparoscopic IPFLR combined with PPH.The degree of internal rectal prolapse(DIRP),Wexner constipation scale(WCS)score,Wexner incontinence scale(WIS)score,and Gastrointestinal Quality of Life Index(GIQLI)score were compared between groups and within groups before surgery and 6 mo and 2 years after surgery.RESULTS All laparoscopic surgeries were successful.The general information,number of bowel movements before surgery,DIRP,GIQLI score,WIS score,and WCS score before surgery were not significantly different between the two groups(all P>0.05).The WCS score,WIS score,GIQLI score,and DIRP in each group 6 mo,and 2 years after surgery were significantly better than before surgery(P<0.001).In group A,the DIRP and WCS score gradually improved from 6 mo to 2 years after surgery(P<0.001),and the GIQLI score progressively improved from 6 mo to 2 years after surgery(P<0.05).In group B,the DIRP,WCS score and WIS score significantly improved from 6 mo to 2 years after surgery(P<0.05),and the GIQLI score 2 years after surgery was significantly higher than that 6 mo after surgery(P<0.05).The WCS score,WIS score,GIQLI score,and DIRP of group B were significantly better than those of group A 6 mo and 2 years after surgery(all P<0.001,Bonferroni)except DIRP at 2 years after surgery.There was a significant difference in the recurrence rate of IRP between the two groups 6 mo after surgery(P=0.011).There was no significant difference in postoperative grade I-III complications between the two groups(P=0.822).CONCLUSION Integral theory–guided laparoscopic IPFLR combined with PPH has a higher cure rate and a better clinical efficacy than laparoscopic IPFLR alone.

GENERAL CONSTITUTIVE EQUATIONS OF AN ER SUSPENSION BASED ON THE INTERNAL VARIABLE THEORY

A microstructural constitutive theory of ER suspensions was formulated in this investigation. The framework was based on the internal variable theory and the mechanism analysis. The ER suspension consists of fine particles with high dielectric constant and the supporting fluid. Under the action of the electric field, the polarized particles will aggregate together to form the chain-like structures along the direction of the electric field. As the size and orientation of the particle aggregates are volatile, and they adjust according to the applied electric field and strain rate, the energy conservation equation and the force equilibrium equation were thus established to determine the orientation and size of the aggregates. Following that, a three-dimensional, explicit form of the constitutive equation was derived based on the interaction energy and the dissipation function of the system. The response of the system under the action of a simple shearing load was considered and discussed in detail. It is found that the shear-thinning viscosity of an ER suspension is wed approximated by the power-law proportional to (Mn)(-D.82).

Rate Constitutive Theories of Orders n and 1n for Internal Polar Non-Classical Thermofluids without Memory

In recent papers, Surana et al. presented internal polar non-classical Continuum theory in which velocity gradient tensor in its entirety was incorporated in the conservation and balance laws. Thus, this theory incorporated symmetric part of the velocity gradient tensor (as done in classical theories) as well as skew symmetric part representing varying internal rotation rates between material points which when resisted by deforming continua result in dissipation (and/or storage) of mechanical work. This physics referred as internal polar physics is neglected in classical continuum theories but can be quite significant for some materials. In another recent paper Surana et al. presented ordered rate constitutive theories for internal polar non-classical fluent continua without memory derived using deviatoric Cauchy stress tensor and conjugate strain rate tensors of up to orders n and Cauchy moment tensor and its conjugate symmetric part of the first convected derivative of the rotation gradient tensor. In this constitutive theory higher order convected derivatives of the symmetric part of the rotation gradient tensor are assumed not to contribute to dissipation. Secondly, the skew symmetric part of the velocity gradient tensor is used as rotation rates to determine rate of rotation gradient tensor. This is an approximation to true convected time derivatives of the rotation gradient tensor. The resulting constitutive theory: (1) is incomplete as it neglects the second and higher order convected time derivatives of the symmetric part of the rotation gradient tensor;(2) first convected derivative of the symmetric part of the rotation gradient tensor as used by Surana et al. is only approximate;(3) has inconsistent treatment of dissipation due to Cauchy moment tensor when compared with the dissipation mechanism due to deviatoric part of symmetric Cauchy stress tensor in which convected time derivatives of up to order n are considered in the theory. The purpose of this paper is to present ordered rate constitutive theories for deviatoric Cauchy strain tensor, moment tensor and heat vector for thermofluids without memory in which convected time derivatives of strain tensors up to order n are conjugate with the Cauchy stress tensor and the convected time derivatives of the symmetric part of the rotation gradient tensor up to orders 1n are conjugate with the moment tensor. Conservation and balance laws are used to determine the choice of dependent variables in the constitutive theories: Helmholtz free energy density Φ, entropy density η, Cauchy stress tensor, moment tensor and heat vector. Stress tensor is decomposed into symmetric and skew symmetric parts and the symmetric part of the stress tensor and the moment tensor are further decomposed into equilibrium and deviatoric tensors. It is established through conjugate pairs in entropy inequality that the constitutive theories only need to be derived for symmetric stress tensor, moment tensor and heat vector. Density in the current configuration, convected time derivatives of the strain tensor up to order n, convected time derivatives of the symmetric part of the rotation gradient tensor up to orders 1n, temperature gradient tensor and temperature are considered as argument tensors of all dependent variables in the constitutive theories based on entropy inequality and principle of equipresence. The constitutive theories are derived in contravariant and covariant bases as well as using Jaumann rates. The nth and 1nth order rate constitutive theories for internal polar non-classical thermofluids without memory are specialized for n = 1 and 1n = 1 to demonstrate fundamental differences in the constitutive theories presented here and those used presently for classical thermofluids without memory and those published by Surana et al. for internal polar non-classical incompressible thermofluids.

The core ideology of Ecological Marxism:Marx is the pioneer of internal factors theory of ecological environment

This paper from the unified visual angle of philosophy and economics has observed Marx's theory of ecological economics, clarified the misunderstanding on Marx's theory of nature and ecological environmental thought at home and abroad for a long time, studied systematically and deeply the Marx's thought that natural and ecological environment is external condition and internal elements of human social economic growth, confirmed firstly Marx is the forerunner who established the theory of internal cause of natural ecological environment. It is of far-reaching academic and practical significance.

Internal biliary fistula due to cholelithiasis:A single-centre experience

AIM： To discuss about the perioperative problems encountered in patients with internal biliary fistula （IBF） caused by cholelithiasis.METHODS： In our hospital, 4 130 cholecystectomies were carried out for symptomatic cholelithiasis from January 2000 to March 2004 and only 12 patients were diagnosed with IBF. The perioperative data of these 12 IBF patients were analyzed retrospectively.RESULTS： The incidence of IBF due to cholelithiasis was nearly 0.3%. The mean age was 57 years. Most of the patients presented with non-specific complaints. Only two patients were considered to have IBF when gallstone ileus was observed during the investigations. Nine patients underwent emergency laparotomy with a pre-operative diagnosis of acute abdomen. In the remaining three patients, elective laparoscopic cholecystectomy was converted to open surgery after identification of IBF. Ten patients had cholecystoduodenal fistula and two patients had cholecystocholedochal fistula. The mean hospital stay was 23 d. Two wound infections, three bile leakages and three mortalities were observed.CONCLUSION： Cholecystectomy has to be performed in early stage in the patients who were diagnosed as cholelithiasis to prevent the complications like IBF which is seen rarely. Suspicion of IBF should be kept in mind, especially in the case of difficult dissection during cholecystectomy and attention should be paid in order to prevent iatrogenic injuries.

SINGULAR ANALYSIS OF BIFURCATION OF NONLINEAR NORMAL MODES FOR A CLASS OF SYSTEMS WITH DUAL INTERNAL RESONANCES

The nonlinear normal modes (NNMs) associated with integrnal resonance can be classified into two kinds: uncoupled and coupled. The bifurcation problem of the coupled NNM of system with 1 : 2 : 5 dual internal resonance is in two variables. The singular analysis of it is presented after separating the two variables by taking advantage of Maple algebra, and some new bifurcation patterns are found. Different from the NNMs of systems with single internal resonance, the number of the NNMs of systems with dual internal resonance may be more or less than the number of the degrees of freedom. At last, it is pointed out that bifurcation problems in two variables can be conveniently solved by separating variables as well as using coupling equations.

Nonlinear dynamic responses of sandwich functionally graded porous cylindrical shells embedded in elastic media under 1:1 internal resonance

In this article, the nonlinear dynamic responses of sandwich functionally graded(FG) porous cylindrical shell embedded in elastic media are investigated. The shell studied here consists of three layers, of which the outer and inner skins are made of solid metal, while the core is FG porous metal foam. Partial differential equations are derived by utilizing the improved Donnell's nonlinear shell theory and Hamilton's principle. Afterwards, the Galerkin method is used to transform the governing equations into nonlinear ordinary differential equations, and an approximate analytical solution is obtained by using the multiple scales method. The effects of various system parameters,specifically, the radial load, core thickness, foam type, foam coefficient, structure damping,and Winkler-Pasternak foundation parameters on nonlinear internal resonance of the sandwich FG porous thin shells are evaluated.

Selection of suitable internal controls for gene expression normalization in rats with spinal cord injury

There is a lack of systematic research on the expression of internal control genes used for gene expression normalization in real-time reverse transcription polymerase chain reaction in spinal cord injury research.In this study,we used rat models of spinal cord hemisection to analyze the expression stability of 13 commonly applied reference genes:Actb,Ankrd27,CypA,Gapdh,Hprt1,Mrpl10,Pgk1,Rictor,Rn18s,Tbp,Ubc,Ubxn11,and Ywhaz.Our results show that the expression of Ankrd27,Ubc,and Tbp were stable after spinal cord injury,while Actb was the most unstable internal control gene.Ankrd27,Ubc,Tbp,and Actb were consequently used to investigate the effects of internal control genes with differing stabilities on the normalization of target gene expression.Target gene expression levels and changes over time were similar when Ankrd27,Ubc,and Tbp were used as internal controls but different when Actb was used as an internal control.We recommend that Ankrd27,Ubc,and Tbp are used as internal control genes for real-time reverse transcription polymerase chain reaction in spinal cord injury research.This study was approved by the Administration Committee of Experimental Animals,Jiangsu Province,China(approval No.20180304-008)on March 4,2018.

CHEMICAL STRUCTURE DEPENDENCE OF THE INTERNAL ENERGY CONTRIBUTION IN RUBBER ELASTICITY

Conformational elasticity theory recently developed has been used to explore the internal energy contribution to the elastic force f(e)/f as a function of strain for poly(cis-1,4-isoprene) and poly(trans-1,4-isoprene). Calculated f(e)/f values are in good agreement with those obtained experimentally. Results show that behavior of f(e)/f is mainly contributed by chemical structure, or intramolecular interaction, supporting the experimental observations, and that the internal energy contribution is strain dependent.

Protein-losing enteropathy caused by a jejunal ulcer after an internal hernia in Petersen's space: A case report

BACKGROUND The incidence of internal hernias has recently increased in concordance with the popularization of laparoscopic surgery.Of particular concern are internal hernias occurring in Petersen's space,a space that is surgically created after treatment for gastric cancer and obesity.These hernias cause devastating sequelae,such as massive intestinal necrosis,fatal Roux limb necrosis,and superior mesenteric vein thrombus.In addition,protein-losing enteropathy(PLE)is a rare syndrome involving gastrointestinal protein loss,although its relationship with internal Petersen’s hernias remains unknown.CASE SUMMARY A 75-year-old man with a history of laparotomy for early gastric cancer developed Petersen's hernia 1 year and 5 mo after surgery.He was successfully treated by reducing the incarcerated small intestine and closure of Petersen’s defect without resection of the small intestine.Approximately 3 mo after his surgery for Petersen’s hernia,he developed bilateral leg edema and hypoalbuminemia.He was diagnosed with PLE with an alpha-1 antitrypsin clearance of 733 mL/24 h.Double-balloon enteroscopy revealed extensive jejunal ulceration as the etiology,and it facilitated minimum bowel resection.Pathological analysis showed extensive jejunal ulceration and collagen hyperplasia with nonspecific inflammation of all layers without lymphangiectasia,lymphoma,or vascular abnormalities.His postoperative course was unremarkable,and his bilateral leg edema and hypoalbuminemia improved after 1 mo.There was no relapse over the 5-year follow-up period.CONCLUSION PLE and extensive jejunal ulceration may occur after Petersen's hernia.Doubleballoon enteroscopy helps identify and resect these lesions.

Emergency treatment and anesthesia management of internal carotid artery injury during neurosurgery:Four case reports

BACKGROUND During skull base surgery,intraoperative internal carotid artery(ICA) injury is a catastrophic complication that can lead to fatal blood loss or secondary cerebral ischemia.Appropriate management of ICA injury plays a crucial role in the prognosis of patients.Neurosurgeons have reported multiple techniques and management strategies;however,the literature on managing this complication from the anesthesiologist’s perspective is limited,especially in the aspect of circulation management and airway management when patients need transit for further endovascular treatment.CASE SUMMARY We describe 4 cases of ICA injury during neurosurgery;there were 3 cases of pathologically proven pituitary adenoma and 1 case of cavernous sinus endothelial meningioma.After the onset of ICA injury,all four patients were immediately transferred for endovascular therapy under general anesthesia with vital signs monitored and mechanical ventilation.Three patients were transferred to the hybrid operating room,and one patient was transferred to the catheter operating room.Three patients underwent covered stent implantation,and one patient underwent embolization.All four patients experienced hypovolemic shock and received blood products infusion and vasoactive drugs to maintain stable circulation.After the neurosurgery,one patient was extubated and returned to the ward,and the other three were delayed tracheal extubation and returned to the intensive care unit.One patient died from serious neurological complications after 62 d in the hospital,but the other three showed good clinical outcomes.CONCLUSION ICA injury imposes a high risk of massive hemorrhage and subsequent infarction.Immediate treatment is critical and requires interdisciplinary collaboration among neurosurgeons,anesthesiologists,and interventional neuroradiologists.Effective hemostatic methods,stable hemodynamics sufficient to ensure perfusion of vital organs,airway safety during transit,rapid localization and implementation of appropriate measures to occlude the damaged vessel are strong guarantees of patient safety.

Deformation and Stress Analysis of the Deepwater Steel Lazy Wave Riser Subjected to Internal Solitary Waves

The dynamic response of the steel lazy wave riser(SLWR)subjected to the internal solitary wave is a key to assessing its application feasibility.The innovation of this paper is to study the dynamic response properties of the SLWR with large deformation characteristics under internal wave excitation.A numerical scheme of the SLWR is constructed using the slender-rod theory,and the internal solitary wave(ISW)with a two-layer seawater model is simulated by the extended Korteweg-deVries equation.The finite element method combined with the Newmark-βmethod is applied to discretize the equations and update the time integration.The ISW excitation combined with vessel motion on the dynamic deformation and stress of the SLWR is investigated,and extensive simulations of the ISW parameters,including the interface depth ratio and density difference,are carried out.Case calculation reveals that the displacement of the riser in the lower interface layer increases significantly under the ISW excitation,and the stresses at a part of both ends grow evidently.Moreover,the mean value of riser responses under a combination of vessel motion and ISW coincides with the ISW-induced ones.Furthermore,the dynamic responses along the whole riser,including the displacement amplitudes,bending moment amplitudes,and stress amplitudes,almost increase with the increase in interface depth ratios and density differences.

INTERNAL STRESS MECHANISM OF CARBON TRANSMISSION UNDER HIGH TEMPERATURE AND HIGH PRESSURE

The problem was found that the nucleation and growth of diamond are different on each side of flaky catalyst in the cubic high pressure diamond synthesis system. Some theories explainning this difference were introduced in the paper. The synthesis cavity and the forces on flaky ctalyst were analysed. The results show that the stress makes the transmission velocity of carbon different on each side of catalyst slice, which causes the difference of nucleation density of diamond between two sides of the slice.

A reliable graded acute liver failure model in rats: treatment with internal bioartificial liver

BACKGROUND: Appropriate animal models are impor- tant for studying acute liver failure. This study was to assess a new suitable rat model for acute liver failure. METHODS: After the right influent hepatic vessels were clamped for a period of time (45, 60 or 90 minutes respec- tively), the animal model was established by removal of the clamp for restoring blood flow of the right lobes while im- mediately removal of the median, left lateral and caudate lobes. Animal survival rate was observed in the following 14 days in each group. To study the pathophysiological chan- ges of the model, some biochemical parameters in 5 con- secutive days were evaluated in the 60-minute group. Inter- nal bioartificial liver was transplanted in the peritoneal cavi- ty to test the reversibility of the model. RESULTS: The survival rate of the models decreased, as the ischemia time of the right lobes prolonged to zero in the 90-minute group, to 50% in the 60-minute group and to 100% in the 45-minute group on the fifth day after opera- tion. The levels of ammonia, alanine aminotransferase, al- kaline phosphatase, total bilirubin and prothrombin were elevated dramatically 12 to 24 hours after operation in the 60-minute group. When internal bioartificial liver was transplanted, the survival rate increased significantly in ad- dition to the levels of ammonia and total bilirubin. CONCLUSION: A period time of ischemic injury in the right lobe followed by 70% liver resection can produce a graded acute hepatic failure model in rats.

Semi-skeletonized Internal Mammary Grafts and Phrenic Nerve Injury:Cause-and-effect analysis

Summary： Phrenic nerve injury after cardiac surgery increases postoperative pulmonary complications. The purpose of this study was to analyze the causes and effects of phrenic nerve injury after cardiac surgery. Prospectively collected data on 2084 consecutive patients who underwent cardiac surgery from Jan. 1995 to Feb. 2002 were analyzed. Twenty-eight preoperative and operation related variables were subjected to logistic analysis with the end point being phrenic nerve injury. Then phrenic nerve injury and 6 perioperative morbidities were included in the analysis as variables to determine their independent predictive value for perioperative pulmonary morbidity. An identical approach was used to identify the independent risk factors for perioperative mortality. There were 53 phrenic nerve injuries （2.5 %）. There was no phrenic nerve injury in non-coronary surgery or coronary surgery using conduits other than the internal mammary artery. The independent risk factors for phrenic nerve injury were the use of internal mammary artery （Odds ratio （OR）=14.5） and the presence of chronic obstructive pulmonary disease （OR=2.9）. Phrenic nerve injury was an independent risk factor （OR=8.1） for perioperative pulmonary morbidities but not for perioperative mortality. Use of semi-skeletonized internal mammary artery harvesting technique and drawing attention to possible vascular or mechanical causes of phrenic nerve injury may reduce its occurrence. Unilateral phrenic nerve injury, although rarely life-threatening, is an independent risk factor for postoperative respiratory complications. When harvesting internal mammary arteries, it should be kept in mind avoiding stretching, compromising, or inadvertently dissecting phrenic nerve is as important as avoiding damage of internal mammary artery itself.