Pumping Force Research Articles

Cardiopulmonary resuscitation. Historical perspectives, physiology, and future directions

To review the historical evolution and rationale for the development of new techniques of cardiopulmonary resuscitation (CPR). English-language studies published after 1960 were identified by computer and manual search using MEDLINE and Index Medicus. Historical references were obtained through a HISTLINE search. Additional information was acquired from personal files and bibliographies of existing literature. Critical review with emphasis on study size, methods, and reproducibility of results. Survival after in-hospital cardiac arrest and institution of CPR is approximately 10% to 15%. Investigation of the physiology of blood flow during CPR has led to the conclusion that flow may occur because of direct cardiac compression or thoracic pump forces. Based on these observations, several new techniques of CPR have been introduced. Interposed abdominal compression, pneumatic vest, and active compression-decompression resuscitation have been shown to improve cardiopulmonary hemodynamics in animal models and humans after cardiac arrest. Only interposed abdominal compression CPR has been shown to improve long-term survival in human subjects after in-hospital cardiac arrest. Although these techniques have shown promising results in animal studies and a limited number of clinical trials, none has gained widespread use. Improved methods of CPR are now available. Selective use of CPR in the hospital and community training in the use of these new adjunctive techniques should have the greatest impact on improved survival after sudden cardiac arrest.

Pacing-induced dilated cardiomyopathy increases left-to-right ventricular systolic interaction.

The right ventricle (RV) receives part of its systolic pumping force from the left ventricle through systolic ventricular interaction. The purpose of this study was to determine the effects of dilated cardiomyopathy on left ventricular to right ventricular (LV-to-RV) systolic interaction. Studies were performed in six normal pigs and in six pigs in which dilated cardiomyopathy resulting in congestive heart failure (CHF) was produced with rapid ventricular pacing at 230 beats per minute for 1 week. In all pigs, we rapidly withdrew blood from the LV apex into a prosthetic ventricle in a single beat, which reduced LV systolic pressure without changing RV or LV end-diastolic pressure, and the resultant instantaneous changes in RV systolic pressure and pulmonary artery flow were determined. The LV-to-RV mean systolic interaction gain was calculated as the change from a normal beat to the instantaneous unloaded beat in mean RV systolic pressure divided by the change in mean LV systolic pressure. Mean systolic pressure gain was approximately 2 1/2 times greater (P < .05) in the CHF animals (0.103 +/- 0.018 mm Hg/mm Hg) than in the normal pigs (0.04- +/- 0.011 mm Hg/mm Hg). These data demonstrate that left-to-right ventricular systolic interaction is significantly greater in dilated cardiomyopathy compared with the normal heart, indicating that the contribution of the left ventricle to RV systolic pressure generation has increased. This is consistent with decreased elastance of the interventricular septum resulting in increased coupling between the ventricles.

High Efficiency, Prototype Annular Electromagnetic Flow Coupler with Ceramic Insulator

An electromagnetic (EM) flow coupler works as a sodium pump. It consists of two parallel ducts under a transverse magnetic field. Conducting fluid in one of the ducts is driven by external power (a mechanical or an electromagnetic pump). Then the duct works as a MHD generator and current is supplied to the other duct. Under the transverse magnetic field, the induced current provides a pumping force to the fluid in the adjacent duct, realizing a high efficiency sodium pump. When the EM flow coupler is used for FBRs, the secondary sodium flow can be used as the generator flow. Then the primary sodium flow is obtained only by the duct under a transverse magnetic field. In the case of an annular EM flow coupler, the ducts are assigned in the annular channel. The annular channel is divided in the circumferential direction, and the generators and pumps are arranged alternatively. Since a radial magnetic field is applied in the flow ducts, the induced current circulates around the flow ducts. So, no bus bar, using a material such as copper which cannot be placed in a high temperature sodium environment, is required. Further, the coupler's compact arrangement around the reactor core can decrease the size of the reactor pool.Experimental results of an annular prototype which was made of stainless steel and had no insulator (non-insulated prototype) have been discussed based on its equivalent electric circuit analysis(1). For the non-insulated prototype, the maximum efficiency was less than 30% since the ohmic loss in the side wall was more than 40% at the peak efficiency. So, an efficiency of more than 60% would be expected if electrical insulation of the side wall were done. In this note, the experimental results are given about the effect that the side wall insulator has on the efficiency.

Electrophysiology of newt skin: Effects of prolactin

Integumental transepithelial potential (TEP) was measured by both in vivo and in vitro (Ussing chamber) techniques in the same adult terrestrial-phase California newts ( Taricha torosa). In both types of preparation, TEP showed a logarithmic relation to external sodium (as Na 2SO 4) concentrations between 0.1 and 10 meq/liter, with in vivo values exceeding in vitro values at all points. K M was ca. 1 and 5 meq/liter for the in vivo and in vitro preparations, respectively. When terrestrial-phase newts were treated with prolactin (PRL; 50 mIU/g/day), in vivo TEP declined significantly within 3 days. In vivo TEP versus [Na +] ext curves of recently collected aquatic-phase newts were found to be not significantly different from those of PRL-treated terrestrial-phase animals. Current/voltage ( I/ V) plots likewise showed that skin from aquatic-phase and PRL-treated terrestrial-phase newts was electrophysiologically alike. Estimates and calculations based on the I/ V relationship suggest that PRL acts primarily to increase the epithelial electrical resistance in the transcellular pathway, with no effect on the electromotive force of the sodium pump.

Amiloride: Effects on myocardial force of contraction, sodium pump and Na +/Ca 2+ exchange

The direct effects of amiloride on myocardial contractility were examined in electrically stimulated left atrial muscle of guinea-pig heart. Amiloride (0.3 to 1.5 mM) produced a positive inotropic effect which, at higher concentrations, was followed by a decline in developed tension. These effects were not accompanied by contracture or arrhythmia and were not affected by a combination of phentolamine, nadolol, cimetidine, tripelennamine and atropine. The above concentrations of amiloride prolonged the action potential duration during the development of the positive inotropic effect; however, no further change in the action potential duration was observed during the decline in developed tension caused by high concentrations of amiloride. Myocardial membrane Na,K-ATPase, ouabain-sensitive 86Rb+ uptake and Na+-dependent Ca2+ efflux from sarcolemmal membrane vesicles were all inhibited by amiloride. The positive inotropic effect of the agent is reduced and the negative inotropic action is enhanced in low Na+ solutions, i.e., under conditions likely to favor Ca2+ influx via Na+/Ca2+ exchange. These results suggest that amiloride, under the present conditions, has a complex interaction with cardiac muscle fibers. Amiloride may produce its inotropic effects in guinea-pig atrial muscle by several mechanisms including sodium pump inhibition, Na+/Ca2+ exchange inhibition, prolongation of the action potential duration, and/or actions such as Na+/H+ exchange inhibition which were not directly addressed in this study.

Study of a downward heat transport device utilizing vapor pressure as the liquid pumping force. (1st report The analysis of the static characteristics)

This paper describes an experiment in the analysis of the heat transport characteristics of a downward heat transport device utilizing the vapor pressure change as the liquid pumping force. The condensate stored in the accumulator returns to the evaporator because of the pressure difference between the accumulator and the condenser produced by unsteady evaporation due to the change of the liquid volume in the evaporator. The vapor pressure in the evaporator was restricted by the accumulator pressure which was almost constant because of the effect of the noncondensable gas, and good temperature control capability was obtained through the passively changing effective condenser length just as in a variable conductance heat pipe. The temperature control capability and the effective condenser length were predicted by the analysis of the simple operation model and the theoretical results agreed well with the experimental data.

Determination of the electromotive force of active sodium transport in frog skin epithelium (Rana temporaria) from presteady-state flux ratio experiments.

The presteady-state influxes and effluxes of sodium across frog skin epithelium have been determined as a function of time while all electrophysiological parameters were maintained constant. The fluxes measured were resolved in the fractions which have passed a pathway through the cells and those that have used a paracellular pathway. The procedure is based on the theory that all presteady-state flux ratios have to be equal to the steady-state flux ratio if only one pathway is involved. The flux ratios for the transcellular route were used to calculate the electromotive force of the sodium pump. The calculation hinges on the assumptions (a) that both influx and efflux have to pass through the sodium pump and (b) that single file diffusion of sodium is not taking place anywhere along the path. The validity of both assumptions is discussed. Our calculated values for the electromotive force of the sodium pump EaNa vary between 146 and 200 mV, which is in agreement with the energy of the ATP/ADP system. There is a distinct indication that, as the electrochemical gradient for sodium opposing the transport is being increased, the emf increases towards an asymptotic value around 200 mV. The relation between the value of EaNa and the cellular phosphorylation potential for ATP is discussed.

Microprocessor—controlled driving unit for artificial hearts

A driving unit for artificial hearts has been produced. This unit uses sodium solution for the transmission of force between the power source and the artificial ventricle instead of the commonly used compressed air and thus avoids the danger of an air embolism. The power source of the hydraulic driving unit is an electromagnet; its armature drives a rolling membrane pump (safety chamber) which moves the transmission fluid (sodium solution) to the artificial ventricle (ellipsoid heart). The incompressible connection between the safety chamber and the ellipsoid heart allows direct control of the membrane motion in the ellipsoid heart and of the volume of pumped blood by measuring the armature stroke. The stroke is measured continuously with an optical position sensor; preprogrammable positions determine the systole end and diastole end respectively, so that the membrane need not strike the housing and is not exposed to additional stress. This volume-controlled mode is characterized by automatic selfregulation according to Starling's law. The microcomputer is programmed in a two-level technique. In the interrupt level the solenoid current is calculated according to the operating mode and armature position every 10 ms which is sufficient to simulate continuous operation. In the main-program level every operational parameter (maximum force, systole end, diastole end; systole duration and beat frequency for the frequency-fixing mode) is displayed on the CRT and can be changed via keyboard entry without any interruption in pumping. The durations of systole and diastole, respectively, are determined by the pumping force, the friction in the hydraulic transmission system and the preload and afterload respectively. The preload and afterload can be calculated from a time-force relation without invasive measurements. The driving unit has shown its haemodynamic efficiency in several in vivo experiments and has been running for 8 months in an in vitro durability test.

Stimulation of urinary acidification by insulin in the turtle bladder.

Addition of insulin to the substrate-containing serosal solution of freshly excised bladders or to that of bladders incubated overnight in substrate-enriched media increases the rate of H+ secretion to a greater extent in the latter (overnight group) than in the former. This effect can be blocked by pretreatment with anti-insulin antibody, suggesting that the stimulation of H+ secretion is a specific effect of insulin. The effect of insulin is concentration dependent with half-maximal stimulation of H+ secretion at 100 mU/ml and maximal stimulation at 250 mU/ml. Other characteristics of the insulin-induced stimulation of H+ secretion were its independence of any effect of Na transport and its absolute requirement for the presence of substrate (glucose or pyruvate) under aerobic conditions only. The proton-secreting action of insulin is associated with an increase in the proton-selective conductance in series with the proton pump while the estimated electromotive force of the proton pump remains constant. Finally, the insulin-induced and aldosterone-induced stimulations of proton secretion are mutually independent, as shown by the additivity of these events and by the fact that the effect of insulin was not blocked by pretreatment with cycloheximide. These data suggest that endogenous insulin modulates the rate of H+ secretion by the in vivo turtle bladder.

Magnetically actuated heart assist pump

Magnetic actuation, requiring no moving, mechanical parts, as a direct magnetic-to-hydraulic energy conversion system for producing pulsatile pumping for a left ventricular assist device (LVAD), was investigated and proven. An axi-symmetric, ellipsoidal pump was built using the three magnetic actuators mounted 120° around the ellipsoidal bladder. Each actuator consists of a variable rate dc-pulsed electromagnet opposite a like polarity rare-earth cobalt permanent magnet attached to the bladder. The ellipsoidal pump geometry imposed two severe design constraints: magnetic force vector alignment and limitation of effective area available for magnetic pumping force application. Efforts to increase the flux density of the electromagnet led to the development of several advanced passive techniques for flux enhancement, e.g., use of smaller permanent magnets critically located in the electromagnet core, shaped core geometry, and flux shell geometry. These have virtually doubled dynamic flux density to values exceeding 0.8 web/m <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> , with no additional power consumption. Preliminary data indicate that shaped, hollow cores, such as prolate spheroids, providing core weight reductions to 60% will enable in excess of 95% solid core flux.

斜軸形油圧ポンプの騒音発生の原因となる加振力に関する研究

Generally, the noise emitted by a bent-axis type of hydraulic pump in normal steady-state operating conditions occurs from internal stress fluctuation of the pump casing, caused by changing of the number of cylinder bores connecting with the delivery port in this paper, the vibrative force of the fluctuations is calculated by development of the method on Fourier's series for trapezoidal waves, which are assumed by the progress of the pressure of the cylinder bores, and it is clarified that the theoretical value of the vibrative force can be calculated using the values of the surge pressure progress in the cylinder bore and the pressure pulsations in the delivery port, which are calculated by known theories (for example gedmann's and Iclulawa's formula), and some experiments were performed to investigate the characteristics o f those calculation vahies. As the result, it is clarified that the calculation method by trapezoid assumption is useful for prediction of the vibrative force in an oil-hydraulic pump.

Effects of electrochemical gradients on active sodium transport in toad urinary bladder.

To determine the concentration dependence of active sodium transport in toad urinary bladder, bidirectional fluxes of sodium were measured at three mucosal sodium concentrations (Cm) (114, 27, and 3 mM), before and after addition of sufficient ouabain to eliminate active transport. The results permit estimation of E, the electromotive force of the sodium pump, and its conductance, ga. E averaged 137 mV and was unaffected by depolarization or by reduction of Cm; ga fell by only 40%, suggesting that a Cm of 3 mM was still above the half-maximal value for the sodium pump. However, net open-circuit transport was estimated to become zero at Cm = 6 mM, owing to backflux through the shunt path, which did not vary with Cm. The flux ratio in the active path exhibited the type of abnormality first described as "single-file pore diffusion," which is attributed to relatively tight coupling between transport and metabolism.

Green light (550 nm) inhibits electrogenic Cl− pump in theAcetabularia membrane by permeability increase for the carrier ion

InAcetabularia, the fast, green-light sensitive depolarization (Schilde, C. 1968,Z. Naturforschung23b:1369) has been reexamined. In the physiological voltage range (−170 to −50mV), it appears to be a light-induced current source. The dose-effect relationship is linear up to about 1 A m−2; about 106 photons (550 nm) cause the transfer of one elementary charge across the membrane. Voltage clamp experiments yield the current-voltage relationship of the fast, light-induced pathway over a voltage range from −240 to +200 mV. This current-voltage-relationship does not intersect with the voltage axis up to membrane potentials of +200 mV; it exhibits maximum current at −190 mV (corresponding to the electromotive force of the electrogenic pump, at which its slope conductance is maximum) and shows smaller current under metabolic inhibition by 2,4-dinitrophenol. External cations, including H+, have no significant effect on the fast, light-induced depolarization. The lag between the stimulus and the onset of the reaction is smaller than 40μsec. On the base of actual carrier models for an electrogenic pump, it can be shown by computer simulation that this light-induced pathway reveals the same features as would be expected if the membrane would become permeable for the unoccupied carrier cation in its Cl− binding state.

ＲＯＳＡ‐ＩＩによるＰＷＲの冷却材喪失事故模擬試験 ＩＩＩ 低温側配管破断時の炉心か酷条件

Experimental condition for the ROSA-II cold-leg break test was selected to test the break configuration predicted by RELAP-3 code in that extremely severe core cooling during blowdown is resulted. Adequacy of the prediction was confirmed by parametric tests on the conditions.The major conclusions are as follows:(1) Effective core cooling during blowdown process can be guaranteed by only small amount of core flow regardless of the flow direction. However core coo1ing becomes very poor when core flow becomes stagnant. Detailed analysis on fluid behavior in primary system is, therefore, needed to well predict fuel surface temperature in such flow condition.(2) Driving force of circulation pump strongly affects blowdown core cooling either by promoting or by degrading the core cooling.

Dependence of the driving force of the sodium pump on rate of transport.

The driving force for active transport of Na+ in the isolated toad bladder, ENa, was measured as the reciprocal slope of the change in conductance with change in short-circuit current after stimulation with antidiuretic hormone. The base-line short-circuit current was altered by change in ambient Na+ concentration or addition of amiloride, maneuvers which alter availability of Na+ at the site of active transport. In the absence of a chemical gradient for Na+ across the bladder, ENa was found to be inversely related to the rate of Na+ transport, a finding incompatible with the simple electrical analogue that has been proposed for the system. The results provide additional support for the view that ENa measured in this way has both energetic and kinetic components.

Effect of light upon membrane potential, conductance, and ion fluxes inRiccia fluitans

The membrane potentialEm, slope conductancegm, and fluxes of86Rb+/K+ and36Cl− have been measured on cells of the aquatic liverwortRiccia fluitans in artificial pond water of pH 4 to 8 and 0.1 to 10mm K0+, in the dark and 1 mW/cm2 of white light. In the darkEm reflects a passive diffusion potential according to the Goldman equation with relative ionic permeabilities,PH/PK/PNa=10∶1∶0.02. In the light,Em of −200 to −240 mV exceeds the most negative ion diffusion potential, i.e.EK, by more than 100mV, is more sensitive to H0+ than K0+, and is reduced to the dark level by uncouplers of phosphorylation. At 1mm K0+,gm is 33 and 50 μS/cm2 in the light and dark, respectively.gm is sensitive to H0+ only in the light, and more sensitive toK0+ in the dark. Current-voltage relationships are given. Light increases the influx at the plasmalemma of86Rb+/K+ and36Cl− less than would be expected from the increase ofEm. It is concluded that the electrogenic pump operates in the dark as a constant current source which is shunted by the diffusive channels whereas in the lightEm approaches the H+-dependent electromotive force of the electrogenic pump.

Resolution of parameters in the equivalent electrical circuit of the sodium transport mechanism across toad skin.

In amphibian epithelia, amiloride reduces net sodium transport by hindering the entry of sodium to the active transport mechanism, that is, by increasing the series resistance (Rser). Theoretically, therefore, analysis of amiloride-induced changes in potential differences and short-circuit current should yield numerical estimates of all the parameters in the equivalent electrical circuit of the sodium transport mechanism. The concept has been explored by analysis of such changes in toad skins (Xenopus laevis) bathed in hypotonic sulphate Ringer's, after exposure to varying doses of amiloride, or to amphotericin, dinitrophenol or Pitressin. The estimated values of Rser, of the electromotive force of the sodium pump (ENa), and of the shunt resistance (Rsh) were independent of the dose of amiloride employed. Skins bathed in hypotonic sulphate Ringer's exhibited a progressive rise in ENa. Amphotericin produced a fall in Rser, while dinitrophenol caused a fall in ENa; washout of the drugs reversed these effects. Pitressin produced a fall in both Rser and Rsh, with a rise in ENa. These results are in accord with earlier suggestions regarding the site(s) of action of these agents.

An apparatus for easy determination of the amount of bound water in cement pastes yielding highly reproducible results

An apparatus designed for the determination of the amount of bound water in cement pastes is described. The drying of the ground paste takes place at 105 °C in a container, the temperature of which is accurately controlled by means of a solid-state proportional temperature regulator. The vapour pressure of water in the container is kept constant independent of the laboratory conditions. This is achieved by letting a small pump force air to bubble through wash-bottles containing distilled water and submerged in a water bath kept at 1°C. The conditioned air stream is heated to 105°C and led into the drying container. The ignition is carried out at 1050°C. The precision of the method and the influence of various testing conditions are discussed. A couple of examples of experimental results are given.

The architectural development of the early mammalian heart

The period 8–10 days post-coitum represents a most critical one in the development of the heart of the mouse; a necessary prerequisite in the concomitant development of the entire embryo. During this period the four chambers which ultimately form the mature heart become defined, as does the bulbus arteriosus. The development observed in the atria and bulbus is less than that in the ventricles. It has been found that, following the establishment of a thin muscular wall to the chambers, the main muscular development in the ventricles and bulbus at this stage is trabecular in form, and the myofibrillar organization in the trabeculae is in general more advanced than in the primitive myocardial wall. Thus it appears that at this stage most of the pumping force is supplied by the trabecular musculature.

Components of Sodium and Chloride Flux Across Toad Bladder

The effect of transepithelial potential difference (psi) on Na and Cl flux across toad bladder was assessed by measuring isotopic flux between identical media at various values of psi. The contribution of edge damage to ionic permeability was eliminated, resulting in relatively high spontaneous psi (-97 +/-4 mv) and low electrical conductance g. Bidirectional Na fluxes were measured simultaneously. Unidirectional Cl fluxes were measured in paired hemibladders at psi = 0 mv or -97 mv. Net Na flux J(Na), at psi = 0 mv, was slightly less than short-circuit current (SCC). At psi = -97 mv, J(Na) averaged 17% of SCC, and was sometimes zero. DeltaJ(Na)/Deltapsi (= g(+)) averaged 60% of g between -97 mv and +75 mv; at -150 mv, g(+) fell, indicating rectification. Analysis of unidirectional Na fluxes indicates low passive conductance (1.5 mumho/mg wet weight), a bidirectional, electrically neutral flux of approximately 0.13 mua/mg, and relatively large conductance of the active transport path at psi >/= -97 mv. The absence of appreciable transstimulation of serosal (S)-to-mucosal (M) Na flux (in response to increasing mucosal Na concentration) indicates that the electrically neutral flux is not exchange diffusion in the usual sense. Analysis of Cl fluxes indicates similar values for passive conductance and neutral flux, suggesting linked neutral flux of Na and Cl. Either the electromotive force of the Na pump E, its conductance g(a), or both are strong functions of psi. The product of these two quantities, Eg(a), is a measure of the "transport capacity" at any given value of psi, independent of the direct effect of psi on J(Na) through the pump path. Eg(a) varies with psi. Hence estimation of the net Na flux or current at any one value of psi, including psi = 0, fails to reveal the maximal transport capacity of the pump, its resting electromotive force (when J(Na) = 0 through the pump), or the dependence of transport capacity on potential.