Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “MANOMETER CONSTANTS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1983

Double tourniquet with linked mercury manometers for hand surgery.

Double tourniquets linked to separate Freon cannisters and two mercury manometers have been effective in maintaining ischemia in over 1,000 consecutive hand surgery operations. The mercury manometers permit constant accurate monitoring of the tourniquet pressure. The cuffs are used alternately. Each is inflated for up to 1 hour in order to limit the duration of nerve compression deep to the cuff. If there is malfunction of either cuff, the other cuff may be inflated at once. This system has permitted sustained ischemia in the upper extremity for up to 3 1/2 hours at a constant tourniquet pressure with no permanent clinically apparent sequellae. There has been no permanent nerve injury, although patients with more than 2 hours of tourniquet time often note hypoesthesia or paresthesia for 1 or 2 days. The alternating double tourniquet linked to a mercury manometer permits up to 3 1/2 hours of continuous ischemia of the upper limb with little risk of nerve damage.

Hand↗
PubMed1992

[Physical modeling of inhalation anesthesia].

A new physical model simulating the pharmacokinetics of volatile anaesthetics is presented. It consists in a ventilator connected to a water manometer. Gas is removed from the gaseous part of this manometer with a constant rate pump. This gas flow is directed thereafter into three capacitances with valves and pumps: one capacitance only contains air, representing the lungs, and the other two olive oil, representing the visceral and muscle compartments. Halothane, enflurane and isoflurane (1 vol%) were administered to this model with different values of cardiac output and alveolar ventilation. There was good concordance between the values of FA/FI that were measured in this model and those calculated by computer simulation. No correction factor was required. Such a physical model may therefore be used to test new techniques of administration of volatile agents.

Anesthesia, Inhalation↗
PubMedDate not supplied

In vitro flow properties of glaucoma implant devices.

PURPOSE: To develop a protocol for testing glaucoma implant devices and to use this protocol to characterize devices currently available. METHODS: The following devices were obtained: Ahmed Glaucoma Valve Implant, Baerveldt Implant, Krupin Eye Valve, Joseph Valve, and OptiMed Glaucoma Pressure Regulator. Pressure per unit time was measured in real-time during ramped pressure perfusion of the implant devices with an open-manometer system. Each device was measured during a 10 minute interval while a constant flow of fluid was pumped into the system. The open manometer allowed the resistance of the devices to generate a pressure head which was monitored by computer. Four independent runs were averaged for each device. RESULTS: The Ahmed devices demonstrated reliable valve performance with a mean opening pressure of 13.65 mm Hg, a facility flow of 1.2 microL/min/mm Hg and a closing pressure of 6.1 mm Hg. The Baerveldt devices had a mean facility flow of 7.56 microL/min/mm Hg. The Joseph devices had the most variable performance, opening from 2.05 to 6.21 mm Hg. Two of 4 Joseph devices had high facility of flow (5 microL/min/mm Hg). The Krupin devices had a mean opening pressure of 6.25 mm Hg in 3 of 4 devices. The remaining Krupin device did not exhibit valve behavior. The OptiMed device did not reveal an opening pressure, and had a mean facility of flow of 7.08 microL/min/mm Hg for high flow and 6.20 microL/min/mm Hg for low flow. CONCLUSION: An objective test protocol for glaucoma implant devices was demonstrated. All implant devices had high facility of flow compared to the normal eye and can be grouped into very high facility (Baerveldt and OptiMed), and high facility (Ahmed, Joseph and Krupin). Only the Ahmed device had consistent valve behavior. None of the devices created enough resistance to explain long-term clinical failure of glaucoma drainage device surgery.

Aqueous Humor↗
PubMed1982

Left ventricular diastolic capacity in man.

Plasma volume expansion with 500 ml of low-molecular-weight dextran was used in 27 patients (nine normal subjects, 13 patients with ischemic heart disease, four with aortic stenosis and one with cardiomyopathy) to increase left ventricular end-diastolic pressure (LVEDP) from a control value of 12.4 +/- 7.0 mm Hg (mean +/- SD) to 23.3 +/- 7.0 mm Hg and end-diastolic volume (EDV) from 84.0 +/- 23.8 ml/m2 to 97.6 +/- 22.9 ml/m2. EDV-LVEDP curves constructed for 12 patients from multiple angiograms at progressively increasing LVEDPs during plasma volume expansion showed an initial part where EDV increased in parallel with LVEDP and a final steep or perpendicular part where EDV increased minimally or not at all as LVEDP exceeded 20 mm Hg. Exponential equations were used to fit diastolic volume-pressure data obtained with catheter-tip manometers in seven patients: the exponential constant, k, was 0.012-0.044 ml-1 and was inversely related to EDV (Spearman's rank correlation coefficient = -1). For comparable EDV, there were no differences in k values between normal subjects and patients with a variety of heart diseases.

Aortic Valve Stenosis↗
PubMed2006

A novel model used to compare water-perfused and solid-state anorectal manometry.

BACKGROUND: Anal pressures are commonly measured using water-perfused and solid-state manometers. We constructed a dynamic model of the anus to compare the agreement and reproducibility of the two types of manometers. METHODS: The model system was constructed using a pig anorectum together with an inflatable bowel sphincter. The pig anorectum was mounted on a jig and the sphincter was inserted external to the internal sphincter. The sphincter pressure was adjusted over the range 20 to 185 mmHg. At each of 24 constant sphincter pressures, triplicate readings were carried out with both manometers. The first measurement by each method was used for the comparison. The replicate measurements were used to calculate measures of repeatability for each method. RESULTS: Measurements by the two manometers were highly correlated (r=0.97). Measurements by the solid state manometer were higher than the water-perfused manometer by 8.1+/-12.2 mmHg (mean+/-SD). Precision (coefficient of variation) for the solid-state manometer (2.8%) was better than for the water-perfused manometer (8.3%). CONCLUSIONS: The new model of the anal canal shows promise as a tool for assessing physiological interventions. The solid-state manometer has many advantages over the water-perfused manometer, providing more consistent measurements at clinically relevant pressures.

Anal Canal↗
PubMed2006

Breath-hold device for laboratory rodents undergoing imaging procedures.

The increased use in noninvasive imaging of laboratory rodents has prompted innovative techniques in animal handling. Lung imaging of rodents can be a difficult task because of tissue motion caused by breathing, which affects image quality. The use of a prototype flat-panel computed tomography unit allows the acquisition of images in as little as 2, 4, or 8 s. This short acquisition time has allowed us to improve the image quality of this instrument by performing a breath-hold during image acquisition. We designed an inexpensive and safe method for performing a constant-pressure breath-hold in intubated rodents. Initially a prototypic manual 3-way valve system, consisting of a 3-way valve, an air pressure regulator, and a manometer, was used to manually toggle between the ventilator and the constant-pressure breath-hold equipment. The success of the manual 3-way valve system prompted the design of an electronically actuated valve system. In the electronic system, the manual 3-way valve was replaced with a custom designed 3-way valve operated by an electrical solenoid. The electrical solenoid is triggered by using a hand-held push button or a foot pedal that is several feet away from the gantry of the scanner. This system has provided improved image quality and is safe for the animals, easy to use, and reliable.

Animals↗
PubMed1976

A new technique for the determination of low CO2 concentrations in liquids.

A new method is described by which total CO2 concentration as low as 0.05 mM can be determined in 2 ml samples of liquid. The principle is based on the measurement of CO2 escape from the liquid into the gas phase following acidification and vigorous stirring of samples. This escape is recorded as pressure variations at constant volume and temperature by means of an electronic manometer connected to the reaction vessel. The precision, which depends on the amount of total CO2 present, ranges from 5 to 15 muM.

Carbon Dioxide↗
PubMed1976

Effect of beta-adrenoreceptor blockers on heart rate and blood pressure in dynamic and isometric exercise.

Previous studies on the effects on heart rate and blood pressure in normals and hypertensive patients during dynamic exercise (ergometer bicycling or treadmill walking) and isometric exercise (sustained handgrip) are reviewed. In one study utilising sub-maximal bicycle exercise in hypertensives, there was a 43% increase in heart rate for a 33% increase in systolic pressure and 5% fall in diastolic pressure. Beta-adrenoreceptor blockade decreased the heart rate level by 18 to 19% for a decrease of systolic blood pressure level by 4 to 11%, whereas the diastolic pressure level was unaffected. A protocol is described utilising a blind indirect blood pressure recording machine ("Auto-Manometer") with which cuff inflation and deflation are automatic and constant, and blood pressure values stored at suitable Korotkov sound phases. The machine also records heart rate. By this method, isometric exercise at 50% of maximal voluntary contraction (sustained handgrip) has been studied in normals and hypertensives off and on different treatments. Both in normals and established hypertensives, there was about a 25% increase in systolic blood pressure during isometric exercise for about a 22% increase in diastolic blood pressure, and 26% increase in heart rate. Normotensive women had the lowest rise in blood pressure and the highest rise in heart rate. Beta-Adrenoreceptor blocking agents lowered heart rate during isometric exercise by 15 to 20% but did not affect the blood pressure level. Since resting blood pressure levels were decreased, the percentage rise in pressure was enhanced following beta-blockers. A combination of a beta-blocker, clonidine and/or a vasodilator produced a reduction in both systolic (24%) and diastolic (12%) pressure, as well as in heart rate (18%), during isometric exercise.

Adrenergic beta-Antagonists↗
PubMed2006

An experimental model of prolonged esophagitis with sphincter failure in the rat and the therapeutic potential of gastric pentadecapeptide BPC 157.

We report a simple novel rat model that combines prolonged esophagitis and parallel sphincters failure. The anti-ulcer gastric pentadecapeptide BPC 157, which was found to be stable in gastric juice, and is being evaluated in inflammatory bowel disease trials, is an anti-esophagitis therapy that recovers failed sphincters. Twelve or twenty months after the initial challenge (tubes sutured into sphincters for one week and then spontaneously removed by peristalsis), rats exhibit prolonged esophagitis (confluent hemorrhagic and yellowish lesions, thinner epithelium and superficial corneal layer, with stratification derangement); constantly lowered pressure of both sphincters (assessed by using a water manometer connected to the drainage port of a Foley catheter implanted into the stomach either through esophageal or duodenal incision); and both lower esophageal and pyloric sphincter failure. Throughout the esophagitis experiment, BPC 157 was given at either 10 micro g/kg, i.p., once a day (last application 24 h before assessment) or alternatively, it was given continuously in drinking water at 0.16 micro g/ml (12 ml/rat). This treatment recovers i) esophagitis (macroscopically and microscopically, at either region or investigated time period) and ii) pressure in both sphincters (cmH2O). In addition, BPC 157 (10 micro g/kg) or saline (1 ml/rat, 5 ml/kg) was specifically given directly into the stomach; pressure assessment was performed at 5 min thereafter. The effect of BPC 157 is specific because in normal rats, it increases lower esophageal sphincter-pressure, but decreases pyloric sphincter-pressure. Ranitidine, given as the standard drug using the same protocol (50 mg/kg, i.p., once daily; 0.83 mg/ml in drinking water; or 50 mg/kg directly into the stomach) had no effect.

Animals↗
PubMed2000

Usefulness of early diastolic flow propagation velocity measured by color M-mode Doppler technique for the assessment of left ventricular diastolic function in patients with hypertrophic cardiomyopathy.

Flow propagation velocity (FPV) of left ventricular (LV) filling flow has been shown to be a useful index for the evaluation of LV diastolic function, which is relatively independent of preload in myocardial infarction and dilated cardiomyopathy, but the usefulness of FPV for hypertrophic cardiomyopathy (HCM) has not yet been determined. In 23 HCM patients and 26 control subjects, peak transmitral flow velocities in early diastole (E) and during atrial contraction (A), E/A ratio, deceleration time of E velocity, and isovolumic relaxation time were measured with the conventional Doppler technique, and FPV was measured from color M-mode Doppler images of LV filling flow. The time constant of LV isovolumic pressure decay (tau) was measured by a micro-manometer-tipped catheter in all HCM patients and 13 control subjects. Flow propagation velocity was significantly lower and deceleration time was significantly greater in HCM patients than in the control subjects, though no significant differences were observed in the other noninvasive indexes. Tau was significantly prolonged in HCM patients compared with that of control subjects (54+/-12 cm/s and 32 +/-7 cm/s, respectively; P<.0001). While the conventional indexes did not correlate with tau among the 36 patients in whom invasive studies were performed, FPV correlated well with tau (r = -0.76, P<.0001). Flow propagation velocity is a useful noninvasive index for the assessment of LV diastolic function in patients with HCM.

Adolescent↗
PubMed2004

Tissue Doppler-derived myocardial acceleration for evaluation of left ventricular diastolic function.

OBJECTIVES: Our purpose was to evaluate a tissue Doppler-based index-peak myocardial acceleration (pACC)-during isovolumic relaxation and in evaluating left ventricular (LV) diastolic function. BACKGROUND: Simple, practical indexes for diastolic function evaluation are lacking, but are much desired for clinical evaluation. METHODS: We examined eight sheep by using tissue Doppler ultrasound images obtained in the apical four-chamber views to evaluate mitral valve annular velocity at the septum and LV wall. The pACC thus derived was analyzed during isovolumic relaxation (IVRT) and during the LV filling period (LVFP). We then changed the hemodynamic status of each animal by blood administration, dobutamine, and metoprolol infusion. We compared the pACC values during IVRT and LVFP over the four different hemodynamic conditions with a peak rate of drop in LV pressure (-dP/dt(min)) and the time constant of LV isovolumic pressure decay (tau), as measured with a high-frequency manometer-tipped catheter. RESULTS: The pACC of the septal side of the mitral valve annulus during IVRT showed a good correlation with -dP/dt(min) (r = -0.80, p < 0.0001) and tau (r = -0.87, p < 0.0001). The mean left atrial pressure (LAP) correlated well with the septal side pACC during LVFP (r = 0.81, p < 0.0001). There was a weak correlation between the mitral valve annulus pACC at the LV lateral wall and mean LAP. CONCLUSIONS: The pACC during IVRT is a sensitive, preload-independent marker for evaluation of LV diastolic function. In addition, pACC during LVFP correlated well with mean LAP.

Animals↗
PubMed1991

The influence of left ventricular relaxation in determination of the intensity of the aortic component of the second heart sound.

In a study of the aortic component of the second heart sound (A2) intensity, using 10 dogs, miniature cardiac accelerometers were attached to the exposed left ventricle (LV) at the apex, and to the surface of proximal aorta, to obtain LV and aortic surface acceleration. Manometer tipped catheters were used to detect aortic systolic pressure and diastolic pressure and time constant of left ventricular pressure fall "T". Drugs (Nitroprusside, Dobutamine and Methoxamine) altered aortic pressure, LV contraction and LV relaxation. When T was +/- 35% of control, the aortic systolic pressure and diastolic pressure were good predictors of A2 intensity. When LV relaxation was impaired, increasing T greater than 135% of control, the A2 intensity for any given aortic pressure was reduced. When relaxation was hyperactive, decreasing T less than 65% of control, A2 intensity was increased. Aortic pressure/T which assessed both aortic pressure and relaxation ability, is a better determinant of A2 intensity than aortic systolic pressure or aortic diastolic pressure alone.

Animals↗