Basic inertial quantities including multi-segment trunk of fit, young males obtained based on personalized data.

Up to now several researchers use values of basic inertial quantities of human body parts obtained for old cadavers. Taking into account the trunk researchers presented this body part often as one segment only and rarely as few-segment part. The purpose of this study was obtaining values of basic inertial quantities of body parts including five parts of the trunk for young, fit living males. Thirty young, fit males (age: 24 ±â€¯4 years, height: 179 ±â€¯6 cm, body mass: 74 ±â€¯7 kg) were directly measured (circumferences and skin-fat folds) and photographed in order to use these data for Clauser et al. (parts of extremities) and Erdmann's (parts of trunk) methods for estimation of mass and location of centres of mass of body parts. These methods take into account personal data for estimating inertial quantities. Relative mass (according to the mass of the whole body) of trunk parts (sum of thorax + abdomen + pelvis but without shoulder girdle) of subjects investigated in this work was similar to that obtained by Dempster for old cadavers. Relative mass differed for shoulders and for lower extremities. Old subjects for both lower extremities had around 31-32% of the whole body mass and young subjects had almost 37%. Procedure for obtaining location of the whole body centre of mass for graphical method (summation of mas) was presented. Obtained data are very important for analyses of arched trunk, e.g. in high jumping, pole vault jumping, rhythmic gymnastics of young, fit athletes and also for models of young passengers in car-crash tests, for ergonomics and medical analyses and other purposes.

Relief of cancer pain in man: alcohol-induced neuroadenolysis vs. electrical stimulation of the pituitary gland.

To explore new methods for the control of intractable pain caused by advanced cancer, the analgesic effect of electrical stimulation of the pituitary gland was investigated in 25 patients. The results were compared with a control study and with the effects of alcohol-induced pituitary neuroadenolysis (NALP) in the same patients. The pain score (0: no pain at all, 4: extreme pain) in the control study was 3.88 +/- 0.33. After electrical stimulation of the pituitary gland it was 1.24 +/- 1.61; and after NALP it was 1.0 +/- 1.60. The pain scores after electrical stimulation and NALP were significantly lower (P less than 0.01) than those in the control study; but there was no significant difference when the two were compared with each other. The duration of pain relief following NALP (59.65 +/- 68.72 days) was significantly longer compared with that recorded following electrical stimulation (2.97 +/- 2.58 days). Autopsy examinations of 3 patients who expired from their malignancies revealed that the pain relief was unrelated to the degree of necrosis induced in the pituitary by alcohol. Naloxone administration did not inhibit the analgesic effect of either NALP or electrical stimulation. The advantages and disadvantages of electrical stimulation, the pain relief mechanism activated by this method, and potential clinical applications are also discussed.

The pituitary inhibitory system: its role in pain perception.

The present study was designed to investigate the pain relief mechanism of electrical stimulation to the pituitary and the relationship between hypothalamic and pituitary analgesic mechanism through the observation of monkey behavior and characteristics of tooth pulp-evoked potentials. The results suggest that pituitary-stimulating analgesia should be differentiated from hypothalamic-stimulating effect. In view of the facts, the theory of the Pituitary Inhibitory System is proposed.

Behavioral and electrophysiological aspects of nitrous oxide dependence.

We examined the effect of 70% nitrous oxide (N2O) on locomotion and visual-evoked potentials (VEP) in rats. The animals exposed to N2O showed an initial decrease of locomotion, followed by development of tolerance and unaltered motor activity during N2O withdrawal. Similarly, an initial decrease of VEP amplitudes was followed by tolerance to N2O. In addition, some amplitudes (N2-P3, P3-N3, and N3-P4) exceeded the control values, indicating an increase of neuronal excitability of the visual system during a long lasting exposure to N2O. The increase of VEP amplitudes was further potentiated by cessation of this gas. The VEP latencies after initial increase, returned to normal and remained unaltered during N2O withdrawal suggesting that the speed of neurotransmission is not essentially changed during chronic exposure to N2O. However, a significant increase of neuronal excitability during chronic N2O exposure, which further increased by cessation of N2O, could be of clinical importance. Therefore, monitoring of VEP, particularly the amplitude values, may significantly improve a detection of altered neuronal excitability during anaesthesia and drug withdrawal.

A method for simultaneous measurement of intragastric, intraduodenal, and intracolonic pressures in the bilaterally vagotomized spinal rat.

A method has been developed where quantitative evaluation of intragastric (IGP), intraduodenal (IDP), and intracolonic (ICP) pressures (cm H2O) can be obtained in the bilaterally vagotomized spinal rat. The preparation is very sensitive to 5-hydroxytryptamine (5-HT) and 5-HT-agonists, carbachol, histamine, dopamine, and/or noradrenaline. The effects of drugs on IGP, IDP, and ICP (increase or decrease) can be assessed and a dose-response curve before and after antagonists can be computed. The described experimental model is simple, reliable, reproducible, and appropriate to study and differentiate the different gastrointestinal system receptors that seem to be involved in the modulation of gastrointestinal motility. The additional advantage in using this method is that drug effects on the motility of stomach, duodenum, and colon can be investigated simultaneously.

Geometric and inertial data of the trunk in adult males.

In this study investigations on geometric and inertial quantities of 15 male patients' trunks are described. Layers of 8 mm were scanned using computerized tomography. Thorax, abdomen, pelvis, and two shoulders and their unchangeable and changeable (muscle, fat, and skin) tissues were investigated. The trunk was also divided into portions and subportions according to anthropological landmarks. By comparing subportions to right non-circular frusta, the volume of the trunk is obtained. Volume, mass, and density of trunk's segments and their tissues are given. The location of the centers of mass of the segments is also provided. Regression equations are presented for the calculation of volume of tissues and of subportions. Application of the data for locating the center of mass of the body, for building anthropometric dummies, and for calculating the load acting on any level of a spine are presented.

Density of trunk tissues of young and medium age people.

In this study the investigations made on about 50 trunk tissue densities are described. They were performed on ten cadavers of both sexes within 24 h of the moment of death. They were 20-40 yr old. The weight of each tissue was measured on a laboratory scale and the volume by placing the tissue in a pycnometer filled with water. The density of 2/3 solid trunk tissues ranged from 1.11 to 1.20 g cm-3. The lowest mean data was obtained for a lung tissue (0.563 g cm-3). The highest density datum known from the literature was that for a compact bone: 1.892 g cm-3. The application of obtained data can be for building dummies (e.g. in experiments of car-crash simulations), as well as in the calculation of inertia values using computerized tomography images.

Tolerance to N2O-induced alterations in somatosensory evoked potentials.

The effect of nitrous oxide (N2O) on somatosensory evoked potentials from the cortical (CEP) and spinal cord (SCP) regions in response to forepaw stimulation was studied in ketamine-anesthetized and mechanically ventilated rats. The CEP was recorded from the skull over the contralateral somatosensory area; the SCP was recorded from the supraspinous ligament at C57-6 and L1-2 levels of the spine. Rats were exposed to 70% N2O for 5 h, whereupon N2O was withdrawn for 2 h. Thereafter, the rats were re-exposed to N2O for 10 min. The N13-P21 component of the CEP, the slow positive wave (P2) of the segmental SCP, and the heterosegmental positive cord dorsum potential (HSP) were significantly suppressed by N2O, while the large negative (N1) component of the segmental SCP remained unchanged. A partial recovery of the CEP and HSP was observed during the 5 h of N2O anesthesia, while significant recovery of the P2 component of the SCP was not observed. The withdrawal from N2O following 5 h exposure caused an augmentation of the CEP (When compared to the control values). Re-exposure of rats to N2O again caused the suppression of these potentials as in the initial exposure. The results suggest that the phenomenon of tolerance to N2O in terms of evoked potentials develops within 5 h in the brain but not in the spinal cord.

Endotoxin protection against pulmonary oxygen toxicity and plasma prostaglandin levels in the rat.

Exposure of rats to high concentrations of oxygen (greater than 95%) at 1 ATA pressure (101 kPa) is lethal within three days. Rats treated with a small dose of endotoxin are protected against these lethal effects of hyperoxia. Recently, we found that the lysine salt of acetylsalicylic acid antagonises this protective action of endotoxin. This suggests that prostaglandin metabolism plays an important role in the protective action of endotoxin against pulmonary oxygen toxicity. Therefore, we measured the plasma levels of 6KPGF1 alpha, a stable degradation product of prostacyclin (PGI2), PGE2 and thromboxane B2, the stable degradation product of thromboxane A2, in rats exposed to air or greater than 95% oxygen for 48 hours. We compared these with the plasma levels of rats treated with endotoxin (Salmonella typhimurium lipopolysaccharide 1 mg/kg) and exposed to air or greater than 95% oxygen for 48 hours. We found that exposure of rats to greater than 95% oxygen for 48 hours leads to a significant rise in the 6KPGF1 alpha levels. Rats exposed to greater than 95% oxygen for 48 hours and treated with endotoxin had significantly higher PGE2 and significantly lower 6KPGF1 alpha plasma levels than saline-treated rats exposed to greater than 95% oxygen for 48 hours.

Myocardial oxygen tensions during ischaemia in fluorocarbon diluted pigs.

Previous work by the authors has shown that, following ligation of the left anterior descending coronary artery (LAD), myocardial oxygen tension (PmO2) in expected areas of maximal ischaemia is maintained at the expense of ischaemic border zones of the infarct area. Post-ischaemic haemodilution with the fluorocarbon containing plasma substitute Fluosol-DA 20% (FDA) could significantly improve PmO2 and pre-ischaemic haemodilution can delay myocardial ischaemia. We now present an analysis of the pattern of PmO2 changes to be seen when myocardial ischaemia is induced following prior haemodilution with FDA. Two groups of juvenile Yorkshire pigs were anaesthetised with intraperitoneal thiopentone, intubated and ventilated with halothane, nitrous oxide and oxygen. After placement of cardiovascular monitoring lines, a thoracotomy was performed. The pericardium was opened and 4 steel-protected gold microelectrodes were placed in the terminal supply area of the LAD in such a way that 2 electrodes were in the area of myocardial ischaema to be produced. One group of pigs were bled (20 ml/kg) and the loss was replaced with equal volumes of FDA. The animals were ventilated with halothane and oxygen and the terminal LAD was ligated. Electrode outputs were recorded on a flat bed recorder and analysed. LAD occlusion in the control animals resulted in similar changes in PmO2 to those described above.(ABSTRACT TRUNCATED AT 250 WORDS)

Myocardial oxygen supply under critical conditions, the effects of hemodilution and fluorocarbons.

This article reviews the factors influencing myocardial oxygen supply and demand. The regulative mechanisms in coronary blood flow, especially in critical conditions, are explained. Myocardial oxygenation in coronary artery disease is discussed with special reference to pharmacological intervention. An extensive evaluation of the effects of hemodilution on both the healthy and diseased heart is presented. Effects of hemodilution with fluorocarbons for the treatment or prevention of myocardial ischemia are shown with the aid of intramyocardial oxygen partial pressure measurements.

Tissue oxygen tension in the cerebral cortex of the rabbit.

Polarographic techniques were employed to measure oxygen partial pressure using 10 micron glass-protected gold microelectrodes. When inserting the electrode into the cortex, a PO2-profile is produced. The average PO2 was about 9 mm Hg. Nearly all measurements were below 25 mm Hg and measurements above 50 mm Hg were rare. When the FiO2 was increased from 0.3 to 1.0, tissue PO2 increased, then gradually decreased. This is probably due to vasoconstriction of pre-capillary sphincters. Acute hypoxia showed the opposite effect, but the autoregulation does not seem to be so effective. When CO2 was added to the inspiratory gas mixture the PO2 increased and showed little tendency to return to normal values. This increase in PO2 is due to the direct effect of CO2 and H+ on the blood vessels, causing vasodilation, and therefore an increase in blood flow and tissue oxygenation.

On-line oxygen uptake measurement (VO2): a computer feed-back controlled rebreathing circuit for long term oxygen uptake registration.

A totally closed feed back controlled anesthesia- and ventilation circuit has been developed feasible to be applied for artificial ventilation with tidal volumes as low as 5 ml at a rate of up to 60/min and for spontaneous ventilation with on-line measurement of physiological lung parameters (pressure, volume, flow). Oxygen inflow is regulated via actual-set value comparison, oxygen inflow is measured and recorded on-line (= oxygen uptake by the connected subject). On-line oxygen uptake (consumption) measurement furnishes a valuable, so far not available parameter to monitor changes in the oxygen transport chain to the tissue and to register physiological oxygen consumption values and derangement of metabolism. First results show that total body oxygen consumption of man in rest is lower than so far expected in the high weight and body surface area groups and that oxygen consumption is decreasing with length and age. Metabolic derangements such as in developing hyperthermia crisis are noticed in a very early stage when therapy is still possible before severe damage has occurred.

Effects of ischemia on the oxygen diffusion coefficients in the brain cortex (studies on Macaca irus).

In this series of experiments changes in oxygen diffusion coefficients were measured in waking primates undergoing focal middle cerebral artery ischemia; Ligation of the middle cerebral artery followed by a decrease of the oxygen diffusion coefficient in the areas supplied by that vessel to levels ten to twenty per cent below normal by twenty-five minutes following onset of ischemia. Following release and re-perfusion diffusion coefficient gradually increases and reaches a super normal peak value three hours after release of ligation. This is followed by a gradual reduction in diffusion coefficient with stabilization at preocclusion levels. In the three experiments described these changes following re-perfusion corresponded with clinical improvement of the neurological status of the monkeys;

A new catheter for quasi-continuous measurement of arterial partial oxygen pressure.

Recently a catheter has been developed based on amperometric measurement principle for in vivo monitoring of PaO2. A study in pigs was performed to compare the cell with a standard method for measuring PaO2. The results show that the cell is capable to accurately measure PaO2.

Continuous intra-arterial PO2 monitoring during thoracic surgery.

Intermittent blood gas sampling has several disadvantages, the most important being that samples are usually taken at set intervals, or when changes in oxygenation are suspected--when it is too late. Another problem is inaccuracy caused by careless blood sample handling. Continuous intravascular PaO2 monitoring eliminates these problems. This study shows that the Continucath sensor is an easy-to-use and reliable monitor, with specific early warning capabilities for hypoxia, thereby improving anesthetic and intensive care management. Its characteristics are: a stabilization period of 10 minutes, a 90% response time of 90 seconds, temperature dependence of 4% per degree celsius, a flow dependence of less than 1% if the flow is more than 5 cm/sec, a drift of less than 0.7% per hour, a correlation coefficient of 0.92 when compared to blood gas analysis during surgery.

Non-invasive, on-line measurement of oxygen consumption during anesthesia.

Oxygen consumption is usually derived from values measured by a thermodilution catheter, i.e. an invasive procedure, with associated risks and calculation errors. Closed circuit ventilation provides a reliable, non-invasive means of access to this parameter of metabolism. Routine application of closed circuit ventilation requires overcoming many, mainly technical, difficulties (e.g. leakage problems, valve malfunctions, and calculations of gas uptake). We developed a computerized closed circuit anesthesia ventilator without these problems. With this system non-invasively measured oxygen uptake is continuously presented on-line. We discuss three representative patients presenting for surgical repair of an abdominal aneurysm. Besides actual changes in metabolism and depth of anesthesia, success or failure of the operation is visible in the pre- and direct post-clamping period. With resuscitative therapeutic interventions, increase in oxygen consumption gives valuable information under changing conditions. We conclude that closed circuit anesthesia is a safe and valuable method for measurement of oxygen consumption.

Oxygen uptake and static lung compliance during automatic ventilation.

Oxygen uptake is an important parameter to control proper tissue oxygen delivery. Oxygen uptake is dependent on adequate lung function and easily disturbed by changes in lung compliance and related parameters such as the tidal volume controlling pressure support. Simultaneous on-line registration of oxygen uptake and lung compliance together with ventilatory pressures applied to achieve preset tidal volumes has been made possible using the computer feedback controlled closed circuit ventilatory system Physio-Flex (Physio Co, Hoofdorp, The Netherlands). The system guarantees for leakage free functioning (maximal leakage 7 mL gas loss/minute) and, therefore, patient oxygen consumption measurements with an accuracy of more than 95%. A specially developed membrane ventilation mode registers on-line flow and displaced volume automatically corrected for temperature, pressure and compressible volume. The current investigation has shown: Decrease oxygen consumption versus oxygen delivery supply dependency may be induced by reflectory decreases of heart rate and cardiac output; in this case a reactive pulmonary parameter change is preceding the event in form of a drop in compliance and corresponding changes in ventilatory pressures necessary to maintain the preset tidal volume. In contrast, decrease of oxygen uptake following changes in cardiac output due to acute hypovolemia has no effect on pulmonary function parameters. This can be diagnostically used as moderate changes of tidal volume also have no significant influence on pulmonary parameters. However, changes due to reduction in depth of anesthesia and relaxation have some influence and need to be excluded.

pO2-profiles in human muscle tissue as indicator of therapeutical effect in septic shock patients.

Automatically stepwise driven pO2 electrodes were transcutaneously inserted into muscle tissue of severely ill septic shock patients. The pO2 profile was plotted from 200 individual measurements registered during 5 minutes and a histogram plotted for documentation. Arterial and venous blood gases, cardiac output, systemic and pulmonary vascular resistance were measured continuously on-line. In septicemia multiple drug schemes are suggested all intending to increase oxygen supply to the tissue and to improve oxygen demand/supply mismatch. So far the attending physician is bound to conclude and continue respectively change the treatment scheme according to the above described macrophysiological parameters. Perfusion distribution and local inhomogenities of tissue oxygen supply remain undetected. In the described study pretreatment pO2 profiles in musculus quadriceps femoris were obtained and measurements repeated in intervals of 10 minutes after start of pharmacological treatment. The changes of pO2 profiles of 20 patients, monitored in such a way over days and weeks, were carefully correlated to the described cardiocirculatory parameters and blood gas analyses. Dopamine was used to improve cardiac function and tissue oxygen supply as well. The investigations show that resulting changes of cardiovascular and blood gas parameters do not always indicate that tissue oxygen supply has really improved. On the other hand there was never an improvement in tissue oxygen supply when no changes of the other parameters had occurred. It is advised to add as a further diagnostic parameter tissue pO2 measurements to get insight if improvement in cardiac and pulmonary function really has the intended effect of improvement of tissue oxygen supply.