Strain Gauge Manometer Research Articles

Fifty Years of Open Heart Surgery at the Mayo Clinic

Fifty Years of Open Heart Surgery at the Mayo Clinic

Timing, propagation, coordination, and effect of esophageal shortening during peristalsis

BACKGROUND & AIMS: Minimal information exists on the characteristics and effect of esophageal shortening during peristalsis in the human esophagus. The aim of this study was to quantify esophageal shortening during peristalsis and determine the relationship between shortening, circular muscle contraction, and generation of propulsive force. METHODS: Ten volunteers had three metal clips endoscopically affixed at the squamocolumnar junction and 4.5 and 9 cm proximal to it, defining proximal and distal segments in the lower esophagus. A strain gauge manometer was positioned within the proximal segment along with a traction force sensing balloon. Axial clip movement was assessed with concurrent manometry and videofluoroscopy during swallowing to examine the determinants of propulsive force. RESULTS: Esophageal shortening was coordinated with circular muscle contraction such that each propagated distally as overlapping segments of contraction at a velocity of about 2.5 cm/s. Propulsive force within the proximal segment occurred after shortening, during the circular muscle contraction, with the magnitude of propulsive force correlated with the degree of distal shortening. CONCLUSIONS: (1) Both circular and longitudinal esophageal muscle contraction occur as propagating segments during peristalsis, with the longitudinal muscle contraction leading the circular muscle. (2) Propulsive force occurs during proximal circular and distal longitudinal muscle contraction. (Gastroenterology 1997 Apr;112(4):1147-54)

Lower Limb Venous Pressure in Diabetic Neuropathy

Distended turgid veins have been noted in the feet of patients with diabetic neuropathy. This study assessed the supine venous pressure and its correlation with diabetic neuropathy and arteriovenous (AV) shunting in the feet of type I and type II diabetic subjects. Seventeen patients with chronic Charcot joints, 11 patients with a history of neuropathic foot ulceration, 14 diabetic control subjects, and 11 normal control subjects were studied. Neuropathy was assessed by vibration and thermal thresholds and standard cardiovascular autonomic neuropathy tests. Supine venous pressure was measured by insertion of a 21-gauge needle connected to a strain gauge manometer into the veins on the dorsum of the foot. Venous PO2 was used as a measure of AV shunting. Venous pressure was raised in the group with chronic Charcot joints (18.9 +/- 4.2 mmHg, P < 0.001 vs. the diabetic control group [11.3 +/- 2.6 mmHg]), the normal control group (12.3 +/- 2.3 mmHg, mean +/- SD), and the diabetic group with a history of neuropathic foot ulceration (16.0 +/- 3.7 mmHg, P = 0.008 vs. diabetic control subjects and P = 0.04 vs. normal control subjects), with a maximum of 28 mmHg. Venous pressure was correlated with heart rate variation to deep breathing, r = -0.61 (P = 0.001), vibration threshold, r = 0.56 (P = 0.001), Valsalva ratio, r = -0.64 (P -= 0.001), warm threshold, r = 0.69 (P = 0.001), and venous PO2, r = 0.43 (P = 0.02). There was no correlation with skin temperature, duration of diabetes, age, HbA1c, random blood glucose, ankle/brachial Doppler index, height, or serum creatinine. Venous pressure is much higher in the neuropathic diabetic limb and is correlated with the severity of neuropathy and with AV shunting.

Strain gauge manometer with pressure up to 0.5 GPa acting inside and on the ends of a free cylinder

A free deforming-cylinder pressure transducer with bonded strain gauges is presented for pressure measurements in liquid media up to 0.5 GPa. Description is given of its operating principle and of its main metrological properties; the overall accuracy of this prototype pressure transducer is inside ±0.25 MPa.

Fiber-optic strain-gauge manometer up to 100 MPa

A practical realization of a novel pressure transducer utilizing a fiber-optic strain sensor and an active element configured to simulate an infinite cylinder with free ends is described. The deformation of such a cylinder depends uniquely on pressure acting from its inside and is independent of the stress resulting from the attachment of the device to the pressure system. The fiber-optic strain sensor is permanently bound to the external surface of the cylinder and as such is fully isolated from the high pressure region. The sensing element of the device consists of a highly birefringent (HB) polarization-maintaining optical-fiber strain gauge. The device was characterized at ambient temperatures for pressure up to 100 MPa. The sensor has inherent advantages such as immunity to electromagnetic interference, safety, direct compatibility with optical data transmission systems, simplicity and cost-effectiveness. It does not require any fiber-optic leadthrough and has significantly increased sensitivity (around 0.1 MPa/sup -1/) compared to similar devices based on electrical strain gauges.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Metrological properties of free cylinder strain gauge manometer up to 0.7 Gpa

Abstract The paper presents metrological properties of strain gauge manometer with an active element, built in form of cylinder with free ends. The cylinder behaves like infinite cylinder and its deformation depends on pressure only, beeing independent on the stress resulting from the connection to the pressure system. Such arrangment minimizes strain hysteresis and assures accuracy class better then 0. 1%. Since the deformation can be calculated precisely, the device does not require calibration and it may be used as a primary pressure standard.

Enhancement of pulsed-dye laser arlation of arterial tissues with blood medium: Effects of laser-induced shock waves

The influence of blood medium on tissue ablation by a pulsed dye laser and its selectivity for atheroma were investigated. The role of shock waves on tissue ablation was also evaluated. Normal and atherosclerotic human aortas were irradiated by a 480 nm pulsed dye laser activated at 5 Hz. The laser was coupled with a single 0.2 mm fiber (Uni-gulde) (40 mjoules/pulse) or a multifiber catheter (14× 150 μm) (100 mjoules/pulse). Shock waves were measured using a fluid-filled catheter connected to a strain gauge manometer. With the Uni-guide, pulse-dye lasing resulted in greater ablation of atheroma in blood (11.6 × 10 −3 mm 3/joule, p <0.001 versus atheroma measured in saline and normal tissue in blood) followed by normal tissue in blood (2.5 × 10 −3mm 3/joule), atheroma in saline (1.71 × 10 −3mm 3/joule, p < 0.05 versus normal tissue in saline), and normal tissue in saline (0.54 × 10 −3 mm 3/joule). With the multifiber catheter, laser ablation was the greatest in atheroma in blood (0.55 ± 0.26 mm 3/joule p < 0.001 versus atheroma in saline and normal tissue in blood), followed by normal tissue in blood (0.27 ± 0.12 mm 3/joule), atheroma in saline (0.14 ± 0.15 mm 3/joule, p < 0.001 versus normal tissue in saline), and normal tissue in saline (0 mm 3/joule). The ablation efficlency of the muitifiber catheter was greater than that of the Uni-gulde ( p < 0.0001) At 100 mjoules/pulse, shock waves were the greatest for atheroma in blood (1.47 mm Hg, p < .005 versus normal tissue in blood, p < 0.001 versus atheroma in saline), followed by 0.28 mm Hg in normal tissue in blood, 0.09 mm Hg for atheroma in saline, and 0 mm Hg for normal tissue in saline. The magnitude of shock waves was correlated with ablation officiency ( r = 0.64). In the same specimens ( n = 5), shock waves were 0 at 25 mjoules/pulse, 0.56 mm Hg/pulse at 50 mjoules/pulse, and 1.45 mm Hg at 100 mjoules/pulse ( p < 0.05 versus 50 mjoules/pulse). Heavily calcifled plaques were also ablated with the laser. The craters created in blood occasionally showed irregular edges; however, no extensive thermal injury was observed. In conclusion, we determined: (1) pulsed dye laser at 480 nm selectively ablates atheromatous tissue; (2) blood medium enhances the ablation efficiency of pulsed-dye laser; (3) ablation efficiency is correlated with the magnitude of shock waves; (4) calcified plaques can be ablated by a pulsed-dye laser; and (5) a multifiber catheter is more sultable for laser angloplasty than the Uni-guide.

Central hemodynamics and 24-hour blood pressure in obstructive sleep apnea syndrome: Effects of corrective surgery

Obstructive sleep apnea syndrome is associated with hypoxemia, respiratory acidosis, and frequent arousals during sleep that induce elevation of both the pulmonary and systemic arterial pressure [1,2]. The prevalence of chronic systemic hypertension in patients with sleep apnea syndrome has been reported to exceed 60% [3,4]. Conversely, the incidence of unrecognized sleep apnea in patients with essential hypertension may be as great as 25% to 35% [5-7]. Hemodynamic abnormalities in patients with obstructive sleep apnea appear to be greatest when there are vigorous inspiratory efforts performed against a closed airway during the apneic episodes [1]. Recently, there has been evidence that some of the hemodynamic derangements, notably casual blood pressure elevation, may improve in a few weeks following tracheostomy [4], specific drug therapy [7], and nasal continuous positive airway pressure [8]. In the report herein, we evaluated both noninvasively and invasively recorded hemodynamic parameters before and after uvulopalatopharyngoplasty in a hypertensive man with obstructive sleep apnea. METHODS Hemodynamic Studies Hemodynamic studies were performed as described previously [9]. The systemic arterial blood pressure was recorded intra-arterially by a thin polyethylene catheter introduced into the brachial artery and connected to a strain gauge manometer. The electrocardiogram and arterial pressures were recorded on a multichannel oscillographic recorder. The systolic, diastolic, and electrically integrated mean arterial pressures were recorded during several respiratory cycles, and 15-second intervals were hand-smoothed to blood pressure values. The cardiac output was recorded by the dye dilution method using a linearly responding monochromatic densitometer and recording continuously in arterial blood. Duplicate curves were plotted on semilogarithmic paper, and cardiac output was derived from the area under the curves by a research technician unaware of the clinical data. The cardiac output was indexed by the body surface area. The stroke index was calculated by dividing the cardiac index by the heart rate. The total peripheral resistance index was calculated by using the formula: mean arterial pressure × 80/cardiac index [9].

Aortic and venous blood pressures in the intact pinto abalone, Haliotis kamtschatkas A

1. 1. At 12°C, strain gauge manometers were used to measure resting blood pressures in the ventricle, aorta, and left efferent ctenidial vein of unrestrained specimens of the pinto abalone, Haliotis kamtschatkana. 2. 2. All pressures were pulsatile with an aortic systolic pressure of 0.53 kPa and a mean efferent ctenidial pressure of 0.13 kPa. 3. 3. Peak aortic pressure occurred slightly after that of the ventricular pressure and was 180° out of phase with that of the efferent ctenidial vein. 4. 4. The resting heart rate was 18 bpm. 5. 5. The pressure wave forms were similar to those recorded in the larger Haliotis corrugata from a warmer environment; however, the magnitudes of the pressures were dissimilar to those of H. corrugata, suggesting that either body size or temperature or both may cause differences in heart rate and blood pressure.

Measurement of arterial pressure-dimension relationships in conscious animals.

Currently, considerable clinical interest exists in the vasoactivity of large coronary arteries due to the prevalence of coronary vasospasm in mediating angina pectoris and even myocardial infarction. Although arterial elastic properties have been studied extensively in acute, anesthetized animal experiments and in vitro preparations, few data are available on these properties in conscious, chronically instrumented animals, where the complicating influences of anesthesia, recent surgery, and acute manipulation of the vessel are minimized. To study vascular smooth muscle in the conscious animal we modified the transit-time dimension measurement technique by designing smaller, higher frequency (7 MHz) transducers, and introducing electronic refinements to accurately measure smaller dimensions (2 mm minimum). We applied this technique to the left circumflex coronary (LCC) artery, along with arterial pressure measurements from either chronically implantable strain-gauge manometers, or microtip catheter manometers, to study dynamic compliance and vascular control mechanisms of these arteries for periods of months in conscious, chronically instrumented animals. Infusion of an alpha-adrenergic vasoconstrictor, methoxamine (50 micrograms/kg/min), caused sustained reduction in LCC diameter (9% +/- 2%) at a time when mean arterial pressure rose by 65% +/- 5% and heart rate and mean coronary blood flow (electromagnetic flow probe) were returned to control levels. Methoxamine induced a marked leftward shift in the pressure-diameter and stress-radius relationships, reducing vascular caliber for any given stress and pressure level. Moreover, smooth-muscle activation raised the effective incremental modulus (Einc) of the coronary arterial wall when compared at similar radii, but it reduced Einc when compared at similar stress or pressure levels. Thus, for any given arterial pressure level the Einc of the LCC artery wall can be reduced considerably by the enhanced smooth-muscle activation elicited by methoxamine. Nitroglycerin (25 micrograms/kg) induced an initial decrease in LCC diameter as pressure fell and LCC blood flow rose. However, dimensions then increased, reaching a maximum 5 minutes later, when LCC blood flow was reduced, and heart rate and left ventricular dP/dt were at control levels. The calcium-channel antagonist, nifedipine, caused similar early changes, with the increase in LCC caliber persisting for 46 +/- 5 minutes while LCC blood flow returned to control in 15 +/- 3 minutes.(ABSTRACT TRUNCATED AT 400 WORDS)

A Study of Pharyngoesophageal Pressure in Patients with Swallowing Disturbance

A great many investigations of human pharyngoesophageal motility have been concerned with the motor activity induced by swallowing actions. The methods utilized in such investigations were mainly roentgenoscopic studies, electromyographic observations and graphic registration of contractions by intraluminal recording instruments (swallowing pressure).The method of measuring the swallowing pressure in the pharyngoesophagus has been used as an open-tubed kymographic system. Recently, a satisfactory method that is able to get accurate recording of pressures in the esophagus has become available. A miniature straingauge manometer using 4 diode transducers was developed for clinical measurement of the pharynuoesonhaueal intraluminal pressure.In this study, variations of pressure in the pharynx and cervical esophagus at swallowing were observed in a group of normal subjects and a group of patients with swallowing dis orders.

Use of a Strain-gauge Manometer for the Measurement of the Pharyngoesophageal Intraluminal Pressure

A miniature strain-gauge manometer using a diod transducer was developed for clinical measurement of the pharyngoesophageal intraluminal pressure. A preliminary observation on 10 normal subjects revealed that high pressure waves (P-wave for peristaltic after Cohen) were consistently found at the levels of the velopharynx and hypopharynx. This method has proved to have several advantages compared with the catheter perfusion technique.

Hemodynamics in the pink abalone, Haliotis corrugata (mollusca, gastropoda). II. Acute blood‐flow measurements and their relationship to blood pressure

AbstractIn the pink abalone, Haliotis corrugata, pulsatile flow and pulsatile pressure were measured at 15°C by electromagnetic and Doppler ultrasonic flowmeters and strain gauge manometers. Flow was pulsatile in all areas of the arterial system investigated, i.e., the aorta, the cephalic arterial sinus and pedal arteries. Flow rates of approximately 2.9 ml/min were measured in the aorta of animals after surgical implantation of electromagnetic flowprobes. The events of the cardiac cycle are correlated with aortic blood flow. Simultaneous recording of pressure and flow suggested that the action of the aortic bulb maintained aortic flow during ventricular diastole.

Regional difference of respiratory changes in pleural pressure between left and right thoraxes in dogs.

Respiratory changes in pleural pressure were recorded simultaneously from the left and right pleural spaces in 6 anesthetized closed-chest dogs in the supine, prone, left lateral and right lateral positions. Saline-filled radiopaque catheters connected to strain-gauge manometers were inserted percutaneously in the left and right pleural spaces by an air tight technique and their tips were placed in the mid-thoracic plane. The esophageal pressure was also recorded with the saline-filled system. The value of respiratory pressure amplitude (deltap, the difference between end-expiratory and minimal inspiratory pressures) in the pleural spaces was significantly greater in the left thorax than in the right in the supine, prone and right lateral positions. In 4 body positions, deltap in pleural pressure was significantly greater than in esophageal pressure. It is concluded that respiratory variations in pleural pressure of the left and right thorax are not the same and that postural change does not produce significant regional difference of the respiratory variations.

The peristaltic movement of the ureter: the in vivo dynamic gradient of the ureteral contraction

Investigation of the peristaltic movement in twenty one healthy humans and eighteen mongrel dogs was undergone by means of the electric strain gauge manometer. The dynamic gradient of the amplitude, frequency and resting pressure versus various recording sites of the ureter were recorded in both humans and dogs. The relationship of the ureteral dynamic gradient to the rate of urine flow, travel rate of ureteral contraction and rhythmicity of the peristaltic waves were established and discussed, to clarify the physiology of the ureter.

Direct percutaneous determination of systemic blood pressure and production of renal hypertension in the cat.

SummaryThe percutaneous, direct method for determination of the blood pressure was applied in the cat, without and with anesthesia. In one group of 5 males and 5 females, single determinations were made, to determine the feasibility of the method. In these animals the blood pressure was measured by 2 means—direct mean pressure with a mercury manometer, and systolic and dia-stolic pressures with a strain-gauge manometer. In this group the single pressures were generally high, and usually higher in the males. In another group, 2 males and 2 females, determinations were made weekly for 7 to 24 weeks. In these cats the initial pressures were also high, but similar in both sexes, but, in all the animals, gradually decreased and became stabilized at a lower level in about 4 weeks. In one male and in one female the production of unilateral renal ischemia, due to moderate constriction of the main renal artery, was followed by the development of hypertension, and, as in other species, the exclusion of the ischemic...

PULMONARY VASCULAR IMPEDANCE IN THE DOG.

Pulmonary vascular hydraulic input impedance was measured in 13 anesthetized openchest dogs with normal sinus rhythm, and 2 dogs with surgically induced atrioventricular block, by means of electromagnetic flowmeters and strain gauge manometers of known frequency response. The linearity of the pulmonary bed was evaluated by measuring impedance while the heart rate, and hence the pulsatile input to the bed, was varied. The pulmonary bed behaved as a quasilinear system, within the limits of accuracy of the methods employed and the range of frequencies tested. The use of input impedance, or oscillatory pressure/flow ratio, to describe some characteristics of the bed is therefore justifiable, and analogies with linear models like the simple transmission line are not unreasonable. The characteristic input impedance averaged 3,094 dyne sec cm -5 kg, or about one-third the magnitude of the pulmonary vascular resistance, and was therefore a significant part of the total opposition that must be overcome in moving blood through the lungs. This impedance to pulsatile flow is not included in calculations of resistance from mean pressure and flow measurements. The pattern of the impedance spectrum suggested that reflections originating from arteries 1.0 mm and less in diameter play a large role in determining input impedance and its variations with frequency. Pulmonary vasoconstriction by 5-hydroxytryptamine (serotonin) altered the impedance pattern in a manner consistent with increased wave reflection and displacement of the dominant reflecting sites to positions nearer the main pulmonary artery. Capillary compression by increased intra-alveolar pressure also increased reflection, but did not alter the sites of reflection significantly, providing further evidence that the normal impedance pattern and its modification by serotonin are both determined by the characteristics of the arterial part of the bed.

STUDIES ON HEPATIC CIRCULATION IN ANAPHYLACTIC SHOCK WITH SPECIAL REFERENCE TO THE PLASMA CONCENTRATION OF CATECHOLAMINES

Hypersensitive reaction to penicillin, or anaphylactic shock is a clinical problem of increasing magnitude. Although hepatic circulation in secondary shock due to trauma or hemorrhage has been extensively studied in animals especially on its irreversibility, hepatic circulation in anaphylactic shock has not yet been fully understood. In this paper, hepatic circulation in anaphylactic shock is discussed in correlation with systemic hemodynamics and the plasma concentration of catecholamines in dogs. The mechanism of the change of hepatic circulation is also mentioned. I HEPATIC CIRCULATION IN ANAPHY-LACTIC SHOCK Systemic and hepatic circulatory dynamics were examined simultaneously, for the furtherclarification of the possible relationship between those two systems. Material and Methods The observations reported in this paper were made on sensitized dogs under thiopentobarbital sodium anesthesia.(1) Adult dogs were sensitized by horse serum. At subsequent intervals after the last sensitization, anaphylaxis were provoked by a intravenous injection of horse serum.(2) Hepatic blood flow were determined by the modified Frank's method. A catheter was introduced from the right creasing magnitude. jugular vein into the hepatic vein and advanced as far as possible. Blood flow from the catheter, which is proved to be proportional to total hepatic flow, was measured directly and then the sampling blood was returned through the left jugular vein. Small amounts of heparin were used to prevent blood clotting in the catheter. (3) Cardiac output was determined by the method of STEWERT-HAMILTON using radio-iodinated serum albumin (RISA). RISA was rapidly introduced into the left ventricle or ascending aorta through a catheter advanced from the carotid artery. Counting of radio-activity changes in blood, which was sampled from the femoral artery, were made by using the Well type scintillation counter. (4) Mean artery pressure was measured by means of a strain gauge manometer connected with a tube in the femoral artery. Portal vein pressure was obtained by a catheter advanced into the vessel from a splenic branch vein and by attaching it to a water manometer. Inferior vena cava pressure was measured at the level of the vena caval ostia of the hepatic vein. (5) Total peripheral resistance was estimated by dividing mean artery pressure by cardiac out put. Splanchnic resistance was also calculated by the same principle.

Respiratory carbon dioxide response curve computer

A special purpose analog computer which automatically plots the alveolar ventilation-alveolar PCo 2 response curve is described. The two inputs to the computer are a differential strain-gauge manometer output voltage which is proportional to the expiratory air flow in the rebreathing system and an infra-red carbon dioxide gas analyser output voltage corresponding to the carbon dioxide concentration in exhaled air. During each respiratory cycle, voltages representing the end-expiratory (alveolar) carbon dioxide and alveolar ventilation for the preceding cycle are fed to the X- and Y-axes respectively of an X-Y plotter. A typical response curve before and after 10 mg morphine is shown.

Effect of mannitol on cerebrospinal fluid pressure. The actions of hypertonic mannitol solutions and of urea compared.

In the search for a safe and effective hypertonic solution to lower cerebrospinal fluid (CSF) pressure and decrease brain bulk, many agents have been tested. 1-4 Recently, 30% urea solution has been utilized for this purpose. 5 Hypertonic solutions of mannitol have been used extensively in animals and humans 6-8 without evidence of toxicity. Mannitol is confined mainly to the extracellular space, is metabolized little if at all, and is excreted fairly rapidly. 9-10 Thus, on theoretical grounds, it appeared that hypertonic mannitol solution, administered intravenously, might be an excellent agent for lowering CSF pressure and reducing brain bulk. Methods Dogs were anesthetized by the intravenous administration of sodium pentobarbital (25 mg/kg), and supplemental anesthetic as needed. An endotracheal tube was inserted and attached to a respirator. Respiration was controlled throughout all experiments. A needle in the cisterna magna was connected to a Statham strain gauge manometer, and cerebrospinal fluid