Peter Löwenhielm

Dynamic properties of the parasagittal bridging beins

SummaryA method for investigating stretching of small blood vessels is presented. Stress and strain properties of the isolated parasagittal bridging veins were studied. These veins were stressed along their long axis and torn apart at various constant strainrates. The bridging veins strain capacity was found to be dependent on strain rate, maximal strain was markedly reduced as the rate was increased. The maximal tension in the veins increases as the time to tearing decreases. The tearing tension was shown to be lower for bridging veins as compared to larger veins (femoral, popliteal, inferior vena cava).ZusammenfassungEine Methode zur Untersuchung der Reißfestigkeit bei Streckung kleiner Blutgefäße wird beschrieben. Die Spannungs- und Dehnungseigenschaften isolierter parasagittaler Brückenvenen (Vv. cerebri sup.) wurden untersucht. Die Venen wurden in ihrer Längsrichtung belastet und rissen bei verschiedenen konstanten Dehnungsgeschwindigkeiten. Das maximale Dehnungsvermögen wurde bei größerer Dehnungsgeschwindigkeit stark herabgesetzt. Die maximale Spannung in den Brückenvenen stieg, wenn die Zeit bis zum Abriß kürzer war. Die Zerreißspannung war für Brückenvenen geringer als für größere Venen (V. femoralis, V. poplitea, V. cava inf.).

Mathematical simulation of gliding contusions.

Abstract A gliding contusion in the acute phase is characterized by a streaklike hemorrhage of venous origin situated subcortically in a paramedial convolution. In later stages perivascular necrosis may develop. This type of injury is caused by head angular acceleration and is often seen in traffic casualties when the head has hit the steering wheel, the dashboard or the windshield. The deformation of the brain matter close to the superior sagittal sinus has been simulated by means of a mathematical viscoelastic model in order to clarify the genesis of the gliding contusions. The blood vessels in the brain matter will be strained as a consequence of the brain deformation which results from head angular acceleration. The highest values of the strain occur subcortically where the blood vessels are injured first. The tolerance levels for gliding contusions have been determined. The calculations which were based on experiments regarding the dynamic properties of the superior cerebral veins and on two alternative injury criteria proposed, indicate that a gliding contusion is not likely to arise if the maximal angular acceleration does not exceed 4500 rad/sec2 or the change in angular velocity does not exceed 70 rad/sec.

Strain tolerance of the vv. cerebri sup. (bridiging veins) calculated from head-on collision tests with cadavers.

SummaryHigh-speed films recorded from head on collision tests with cadavers have been analysed with respect to the angular acceleration and angular velocity which were evaluated with Smoothed Cubic-Spline Functions. These results compared with the autopsy findings in these cases and data from studies on angular acceleration to the head of squirrel monkeys carried out by Unterharnscheidt and Higgins indicate the bridging vein disruption due to rotational movement of the head is obtained when the angular acceleration exceeds 4500 rad/sec2 and/or the change in angular velocity exceeds 50 rad/sec. These tolerance levels are compared with data from collision experiments on living human beings.ZusammenfassungMit Hilfe der Smoothed Cubic-Spline Functions wurden Winkelbeschleunigung und Winkelgeschwindigkeit des Kopfes auf Grund von High-speed-Filmen berechnet, die bei frontalen Kollisionen mit Leichen aufgenommen wurden. Die Resultate wurden mit den Sektionsbefunden in diesen Fällen und Daten verglichen, die bei Studien über die Winkelbeschleunigung des Kopfes von Affen (Samiri sciureus) durch Unterharnscheidt u. Higgins gewonnen wurden. Es zeigt sich, daß Rupturen der parasagittalen Brückenvenen dann auftreten, wenn die Winkelbeschleunigung des Kopfes 4500 rad/sec2 überschreitet und/oder eine Veränderung der Winkelgeschwindigkeit von mehr als 50 rad/sec vorliegt. Diese Toleranzgrößen werden mit Daten verglichen, die bei Versuchen mit lebenden Menschen gewonnen worden sind.

The healing process of anastomoses of the colon

In spite of modern suture materials and different techniques in colonic anastomoses after resection, leakage is still the most feared complication in colonic surgery. In female pigs of Swedish land breed, standardized 5-cm long colonic resection was performed 10 cm above the peritoneal deflection, usign either a single layer of Gambee-stitches (n=6, Vicryl® 4-0), two-layer interrupted stitches (n=6, Vicryl® 4-0) or the intraluminal stapling device (n=6, ILS Ethicon®). After one week, the animals were sacrificed and an anastomotic index was calculated usingin vitro x-ray. Also, anastomotic circulation (calculated by the microsphere technique), breaking strength, and histologic evaluation were performed. All animals survived and no leakage was observed. The time to perform, the anastomosis was significantly shorter (P<0.05) for the stapling device compared with the manual techniques used. The anastomotic index was lower (P<0.05) for two rows (0.24) compared with Gambee-stitches (0.38) or stapler anastomoses (0.37). There were no differences in blood flow among the three groups and no differences in breaking strength. Macroscopic investigation revealed mucosal defects in two of the stapled anastomoses and histologic investigation showed small areas of necrosis. The stapling device did not induce any inflammatory reaction. On the other hand, a severe inflammatory reaction was seen when using conventional suture materials. In conclusion, this study shows that a single row of Gambee-stitches is equal to the ILS stapling device when performing colonic anastomoses and these two methods seem to be superior to the two-layer technique.

Computer-assisted systems for forensic pathology and forensic toxicology.

A computer software, RättsBASE (RB), was developed for all forensic pathology units in Sweden and introduced in 1992. Simultaneously, a corresponding software, ToxBASE (TB), was developed for the Department of Forensic Toxicology, where all forensic toxicology in Sweden is managed. Both of the databases were created using dBASE IV, and the programming was carried out according to specifications from the staff at the forensic toxicology and forensic pathology units. since the development or RB and TB was coordinated, the systems can run together smoothly. The purpose of both systems was to automate the offices and to enable compilation of detailed statistics. Installation of Novell Netware and ISDN-connections (Integrated Service Digital Network) has enabled rapid communication between the units and easy compilation of nationwide statistics of forensic pathology and forensic toxicology. the systems offer a wide spectrum of reports and include a simple module for evaluation of the importance of the forensic efforts for th whole death investigation. The configuration of the softwares has also enabled processing of a large amount of related toxicological and autopsy data that in turn has yielded a base for compilation of toxicology interpretation lists. This article includes a summary of the features of the software and a discussion of its benefits and limitations.

Number of addictive substances used related to increased risk of unnatural death: a combined medico-legal and case-record study.

BackgroundSubstance use disorders have repeatedly been found to lead to premature death, i.e. drug-related death by disease, fatal intoxications, or trauma (accidents, suicide, undetermined suicide, and homicide). The present study examined the relationship between multi-drug substance use and natural and unnatural death.MethodsAll consecutive, autopsied patients who had been in contact with the Addiction Centre in Malmö University Hospital from 1993 to 1997 inclusive were investigated. Drug abuse was investigated blindly in the case records and related to the cause of death in 387 subjects.ResultsEvery substance apart from alcohol used previously in life added to the risk of unnatural death in a linear way. There were independent increased risks of fatal heroin overdoses or undetermined suicide. Death by suicide and violent death were unrelated to additional abuse.ConclusionThe number of drugs used was related to an increased risk of unnatural death by undetermined suicide (mainly fatal intoxications) and heroin overdose.

Healing of esophagojejunal anastomoses after experimental total gastrectomy. A comparative study using manually sutured or stapled anastomoses.

In construction of the eosphagojejunostomy after total gastrectomy, the EEA stapled (US Surgical Corporation, Norwalk, CT) and the two-layer interrupted 3-0 Dexon anastomoses are compared concerning the radiological appearance, breaking strength, circulation, and collagen concentration. Thirty female pigs were used. After total gastrectomy and Roux-en-Y preparation, the pigs were randomized to achieve sutured or stapled anastomoses. 141Ce-labeled microspheres were used for measurements of anastomotic blood flow. After the pigs were killed, the breaking strength of the anastomosis was recorded, the collagen content determined, and an anastomotic index calculated comparing two perpendicular diameters in the anastomosis and 5 cm above. Breaking strength, leakage frequency, and anastomotic index were the same in the two groups. One week after surgery, there was a significant increase in anastomotic circulation (p less than 0.05) in both the sutured and the stapled anastomoses compared to controls. Collagen increased equally with time in the two groups (p less than 0.01). The stapled esophagojejunostomy was faster to perform (20 min) than the sutured (28 min) (p less than 0.05).

The healing process in high and low anterior resection of the rectum

The reason for the higher leakage frequency after low anterior resection compared with high resection is unexplained. With the development of stapling devices, we have a unique opportunity to investigate anastomotic healing during standardized conditions. In female pigs, six in each group, a high anterior resection was performed by resection of a 5-cm colon segment, 10 cm above the peritoneal fold, and low anterior resection was performed after resection of a 5-cm segment at the peritoneal fold and downward. Differences in healing parameters,i.e., blood flow, breaking strength, and radiologic and histologic appearance between low and high anterior resection, were evaluated. Two leakages occurred after low and none after high anterior resection. The anastomotic index was 0.37 (high) and 0.26 (low) (P<0.05). The breaking strength was higher in low resections; this might be due to the thicker wall. There were no differences in blood circulation between high and low anastomoses, but the blood flow was significantly higher in the anastomotic area in both groups. This is probably due to the inflammatory reaction taking place in the healing anastomoses. This study, performed in a standardized fashion with a stapler adjusted to wall thickness and size of the intestine, cannot, on the basis of microcirculation, explain why leakage is more common in lower anastomoses.

The effect of the unrestrained back seat passenger on the injuries suffered by drivers and front seat passengers in head-on collisions

SummaryIn head-on collisions, loose items in the rear of the car, such as luggage or unrestrained back seat passengers can cause substantial loading on the back of the front seats. The purpose of this paper is to study if such loading increases the injury severity for the front seat occupants. Data were collected from all fatal automobile accidents for a period of 1 year in Sweden. Information was collected about the survivors as well as the deceased. Head-on collisions were selected, and the injuries of the front seat occupants were scored according to the Abbreviated Injury Scale (AIS) and the Injury Severity Score (ISS). In evaluating the injury severity, the collision energy was taken into account. The results indicate that belted front seat passengers sustain a higher injury risk with an unrestrained passenger in the back seat. These results are valid for collision speeds below 45 km/h.ZusammenfassungBei Frontalkollisionen können lose Gegenstände auf den Rücksitzen von Personenkraftwagen — wie Gepäck, nicht angegurtete Passagiere — zu einer erheblichen Belastung der Rücklehne der Vordersitze führen. In der vorliegenden Studie wird untersucht, ob durch eine derartige Belastung die Schwere der Verletzungen bei Vordersitzinsassen erhöht wird. Die erforderlichen Daten stammen von sämtlichen Kraftwagenunfällen mit tödlichem Ausgang, die sich während 1 Jahres in Schweden ereignet haben. Die Angaben betreffen auch die Überlebenden, und die Körperverletzungen beim Fahrer und Beifahrer auf dem Vordersitz der Fahrzeuge wurden entsprechend der „Abbreviated Injury Scale“ (AIS) und der „Injury Severity Score“ (ISS) aufgeschlüsselt. Bei der Bestimmung der Verletzungsschwere wurde die Kollisionsenergie berücksichtigt. Die Resultate deuten daraufhin, daß die Fahrzeuginsassen auf den Vordersitzen einem größeren Verletzungsrisiko ausgesetzt sind, wenn sich ein nicht angegurteter Insasse auf dem Rücksitz befindet. Dieses Resultat gilt für Kollisionsgeschwindigkeiten unter 45 km/h.

Digoxin, magnesium, and potassium levels in a forensic autopsy material of sudden death from ischemic heart disease

SummaryIn 91 cases where the cause of death was heart disease, digoxin, Mg and K concentrations in serum and ventricular myocardium were measured post mortem. Forty per cent were positive for digoxin in both serum and myocardium. The mean serum level was 5.1±2.4 nmol/l and the mean myocardial level was 42.6±27.5 ng/g. Correlation could be established between serum and myocardial concentrations of digoxin. There were statistically significant differences in serum as well as in myocardial digoxin levels in persons on 0.13 mg and 0.25 mg per day, respectively. Myocardial levels of Mg and K were low as generally found in persons with ischemic heart disease. There was no correlation between these levels and myocardial digoxin concentrations. Caution must be exercised in the assessment of digoxin results from cadaver samples because of the postmortem rise of digoxin serum concentrations. Considering this fact, the results still indicate that the prevalence of toxic digoxin concentrations might be more common than previously thought.ZusammenfassungIn 91 Obduktionsfällen, bei denen der Tod die Folge von Herzkrankheiten war, fand sich Digoxin in 40% der Fälle sowohl im „Blutserum“ als auch im Myocard. Die durchschnittliche Konzentration war 5,5±2,4 nmol/l im Serum und 42,6±27,5 ng/g im Myocard. Es bestand eine Korrelation zwischen den Konzentrationen im Serum und im Myocard. Bei Personen, die 0,13 mg resp. 0,25 mg Digoxin täglich eingenommen hatten, lagen statistisch signifikante Unterschiede sowohl bezüglich der Serum- als auch Myocard-Digoxin-Konzentration vor. Die Mg- und K-Konzentrationen im Myocard waren niedrig, wie dies im allgemeinen bei Personen mit ischämischen Herzkrankheiten der Fall ist. Bei der Beurteilung der Resultate von Untersuchungen auf Digoxin in Leichenteilen muß beachtet werden, daß die Konzentration des Digoxin im Serum postmortal steigen kann. Selbst wenn dies berücksichtigt wird, deuten die Untersuchungsresultate darauf hin, daß toxische Digoxinkonzentrationen bei Personen, die unerwartet infolge von Herzkrankheiten verstorben sind, häufiger vorkommen als bisher angenommen wurde.