Impacts to the chest of PMHSs - Influence of impact location and load distribution on chest response.

The chest response of the human body has been studied for several load conditions, but is not well known in the case of steering wheel rim-to-chest impact in heavy goods vehicle frontal collisions. The aim of this study was to determine the response of the human chest in a set of simulated steering wheel impacts. PMHS tests were carried out and analysed. The steering wheel load pattern was represented by a rigid pendulum with a straight bar-shaped front. A crash test dummy chest calibration pendulum was utilised for comparison. In this study, a set of rigid bar impacts were directed at various heights of the chest, spanning approximately 120mm around the fourth intercostal space. The impact energy was set below a level estimated to cause rib fracture. The analysed results consist of responses, evaluated with respect to differences in the impacting shape and impact heights on compression and viscous criteria chest injury responses. The results showed that the bar impacts consistently produced lesser scaled chest compressions than the hub; the Middle bar responses were around 90% of the hub responses. A superior bar impact provided lesser chest compression; the average response was 86% of the Middle bar response. For inferior bar impacts, the chest compression response was 116% of the chest compression in the middle. The damping properties of the chest caused the compression to decrease in the high speed bar impacts to 88% of that in low speed impacts. From the analysis it could be concluded that the bar impact shape provides lower chest criteria responses compared to the hub. Further, the bar responses are dependent on the impact location of the chest. Inertial and viscous effects of the upper body affect the responses. The results can be used to assess the responses of human substitutes such as anthropomorphic test devices and finite element human body models, which will benefit the development process of heavy goods vehicle safety systems.

Deep inferior epigastric perforator flap: an anatomical study of the perforators and local vascular differences.

The objective of this study was to determine precise localization and external diameter of the lower abdominal wall perforators as well as to investigate some vascularity differences between the same parts of perfusion zones II and III according to Hartrampf perfusion zones. The study was performed on 10 fresh cadavers (20 hemiabdomens) using the gelatin injection technique. All perforators were identified, and their localization and diameter were noted. Measurements were made at the level of the fascia. We noted localization and diameter of arteries on cross-sectional planes of either part of the flap. The median sum of the external diameter of all arteries in zone I was 17.01 mm. The median sum of the external diameter of all arteries in the medial 1/3 part of zone III was 4.17 mm, and in the medial 1/3 part of zone II, it was 0.96 mm. The median sum of the external diameter of all arteries in the intermediary 1/3 part of zone III was 2.16 mm, whereas in the intermediary 1/3 part of zone II, it was 0.81 mm. Significant differences were recorded between proximal and middle horizontal regions of zones II and III and between medial vertical part of zone III and medial vertical part of zone II. Anastomoses between zones I and II are considerably smaller compared with anastomoses between zones I and III. The best vascularized parts of the lower abdominal wall were perfusion zone I, then the inner 2/3 of zone III and medial 1/3 of zone II.

Anatomy of the ligamentum venosum arantii and its contribution to the left hepatic vein and common trunk control. A study on cadaveric livers.

BACKGROUND: The control of the left hepatic vein (LHV) and the common trunk of the middle hepatic vein (MHV) and LHV (CT) is considered difficult during liver resection and could be improved by detailed knowledge on the ligamentum venosum Arantii (LV). AIM: The aim of this study was to describe the LV and its connections to the LHV and the CT and to present surgical relevance of the obtained data. MATERIAL AND METHODS: During autopsy of 50 cadavers of both sexes, the LV was exposed, measured and then dissected, simulating a surgical maneuver to facilitate the approach to the LHV and CT. The extrahepatic parts of the LHV, MHV and CT were measured. RESULTS: The LV was 52-70 mm long and 5-8 mm thick. It had a fibrotic structure and was not patent in 96% of the cases. The extrahepatic part of the LHV measured 3-19 mm, that of the MHV 3-18 mm and that of the CT 4-15 mm. CONCLUSION: LV dissection facilitated extraparenchymatous clamping of the hepatic veins: the extrahepatic parts of the LHV and CT measured > 3 mm in 86 and 84% of the cases, respectively.

Anatomy and surgical relevance of the hepatocaval ligament. A study on cadaveric livers.

BACKGROUND: There are nearly no data on the hepatocaval ligament (HCL) in the anatomical literature, though it is of high importance during surgery of the right hemiliver. AIM: The aim of this study was to determine the frequency of the HCL, its description and its relations to the inferior vena cava (IVC) and the right hepatic vein (RHV) as well as the evaluation of the surgical relevance of the data obtained. MATERIALS AND METHODS: The dissection of the livers of 43 cadavers of both sexes was performed and the presence of the HCL was established. The ligament was measured and dissected to expose the IVC and the extrahepatic part of the RHV from its inflow to the liver parenchyma. RESULTS: The ligament was present in 77% of the cases. It was 12-35 mm long and 3-18 mm wide. The extrahepatic part of the RHV was 2-12 mm long. CONCLUSION: Dissection of the HCL revealed the terminal extrahepatic part of the RHV in all cases. Anatomically, resection of the right hemiliver with elective vascular control would be possible in 85% of the cases in which the length of the extrahepatic part of the RHV was > or =3 mm.

An experimental model of reproducible liver trauma.

The aim of the study was to create an experimental model of reproducible and controllable liver trauma in pigs. The few reported experimental models of liver trauma use the "clamp and crush" mechanism of injury and do not cause reproducible liver injury. In the present study, force was applied through the thoracic wall to mimic a chest injury. Nine pigs were used as experimental animals. In anaesthetised animals, blunt liver trauma was caused with a crossbow using an arrow with a spherical aluminium head as a projectile. Liver injuries of stages II to III according to liver injury scale were inflicted on all the animals. The stage of liver trauma was proportional to the pressure impulse (ratio between the product of the arrow's mass (m) and the velocity (v) and the contact surface area of the arrow (S)). The presented model of controllable liver injury will enable the study of various aspects of liver trauma since the experiment can be designed in such a way to produce a spectrum of liver injuries.

Anatomical basis of the liver hanging maneuver.

BACKGROUND/AIMS: The anterior approach to right hepatectomy using the liver hanging maneuver without liver mobilization claims to be anatomically evaluated. During this procedure a 4 to 6-cm blind dissection between the inferior vena cava and the liver is performed. Short subhepatic veins, entering the inferior vena cava could be torn and a hemorrhage, difficult to control, could occur. METHODOLOGY: On 100 corrosive casts of livers the anterior surface of the inferior vena cava was studied to evaluate the position, diameter and draining area of short subhepatic veins and inferior right hepatic vein. The width of the narrowest point on the planned route of blind dissection was determined. RESULTS: The average value of the narrowest point on the planned route of blind dissection was 8.7+/-2.3mm (range 2-15mm). The ideal angle of dissection being 0 degrees was found in 93% of cases. In 7% we found the angle of 5 degrees toward the right border of inferior vena cava to be the better choice. CONCLUSIONS: Our results show that liver hanging maneuver is a safe procedure. With the dissection in the proposed route the risk of disrupting short subhepatic veins is low (7%).

Congruence between the courses of the biliary ductal and the hepatic arterial systems.

The development of diagnostic methods and new surgical techniques means it is increasingly important to have accurate knowledge of the anatomy of the hepatic arterial and biliary systems, including their variations, at extrahepatic and intrahepatic levels. The aim of this study was to determine how often the biliary and arterial systems run together and branch in the same pattern. Fifty corrosion casts of the liver were used to analyse the origin and branching patterns of arteries and the confluences of bile ducts. In addition, both systems were analysed to determine the frequency of normal arrangements and variations. The congruence of the course of both systems was analysed at the porta hepatis and in the left and right hemilivers down to the segmental level. A congruent course of the arterial and the biliary systems was identified in 38% of cases at the porta hepatis, in 32% of cases in the left hemiliver and in 30% of the right hemiliver. The congruence of both systems at the porta hepatis and in the left hemiliver was identified only if both systems were normal. In the right hemiliver, however, the congruence of both systems was identified even when both systems were variable, but only in 10% of cases. The results of the study show that, on the basis of knowledge of the course and branching of one system, the other system cannot be predicted.

Anatomical variations of the right hepatic veins and their relevance to surgery.

BACKGROUND/AIMS: In a morphological study of the right hepatic veins anatomical characteristics of surgical importance were looked for. METHODOLOGY: 110 cadaveric human livers were prepared by the corrosion casts method. The confluence patterns of the superior right hepatic vein, the hepatocaval confluence, the accessory right hepatic veins and the anastomoses between hepatic veins in the right hemiliver were examined. RESULTS: Four types of the superior right hepatic vein, based on the length of its trunk and the confluence pattern of its main tributaries were determined and their frequency was calculated. Type I was found in 20%, type II in 40%, type III in 25% and type IV in 15%. Accessory right hepatic veins with a minimal caliber of 0.4 cm, which were always present in type IV, were also found in other types, all together in 27% of the casts. The tributary-free part of the superior right hepatic vein at hepatocaval confluence was longer than 1 cm in 77%. In the right hemiliver 109 anastomoses were found in 29/110 liver casts. CONCLUSIONS: Knowing the characteristics of different superior right hepatic vein types and of the accessory right hepatic veins may be useful in segment-oriented liver resections and in right side living donor resections.

Anatomical variations of the cystic artery.

Thorough knowledge about the origin of the cystic artery is surgically important, especially when intraoperative or post-operative bleeding occurs in the gallbladder fossa. The arterial supply of the gallbladder was studied in 81 livers. The gallbladder was supplied by one cystic artery in 86% and by two arteries in 14% of cases. When a single artery was present, it originated from the right hepatic artery in 53% of livers. Other origins included the anterior or the posterior sectional hepatic artery, the replacing right hepatic artery, and in 5% of cases, segmental arteries for segments 4, 5, 6 and 8. When two cystic arteries supplied the gallbladder, both most commonly originated from the right hepatic artery (7% incidence). In 1% of cases, a subsegmental branch for segment 6 and a subsegmental branch for segment 5 respectively, originated from the cystic artery.

Anatomical variations of the arterial pattern in the right hemiliver.

The arterial supply to the right hemiliver was studied in 80 liver casts. The arteries were divided into 10 groups according to their origin and branching pattern. The right hemiliver was supplied by one artery in 96% of cases and by two arteries in 4%. When there was only one artery it originated from the proper hepatic artery in 73/77 cases and from the superior mesenteric artery in 4/77 cases. The replacing right hepatic artery which originated from the superior mesenteric vessel supplied the whole right hemiliver in 5% of cases. The incomplete replacing right hepatic artery which supplied only a part of the right hemiliver was found in 4% of cases. The anterior section (segments 5 and 8) was supplied by one artery in 61%, by two arteries in 30% and by three arteries in 9% of cases. The posterior section (segments 6 and 7) was supplied by one artery in 66%, by two arteries in 31% and by three arteries in 3% of cases. Segments 5 and 7 were predominantly supplied by one artery, whereas segments 6 and 8 by two arteries.

Anatomical variations of the arterial pattern in the left hemiliver.

The arterial supply to the left hemiliver was studied in 70 liver casts. The arteries were divided into 15 groups according to their origin and branching pattern. The left hemiliver was supplied by one artery in 53% of cases, by two arteries in 40% and by three arteries in 7%. The left hepatic artery, which originated from the proper hepatic artery, supplied all three left segments in 39% of specimens. The replacing left hepatic artery, which originated from the left gastric artery, supplied the whole left hemiliver in 3% of cases. The incomplete, replacing left hepatic artery supplied segments 2, 3 and a part of segment 4 in 6% of cases, and only segments 2 and 3 in 11%. There was one segmental artery for segment 2 in 86%, and two in 14%. Segment 3 was supplied by one artery in 87%, and by two in 13%. Segment 4 was supplied by one artery in 39% of cases, by two arteries in 43%, by three in 14% and by four arteries in 4%.