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Results for “Venous Pressure”

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At least 19 recordsLinked to original sources
PubMed1978

[The influence of changes in body position on intraocular pressure, episcleral venous pressure, and blood pressure (author's transl)].

The intraocular pressure, the ophthalmic artery pressure, and the episcleral venous pressure increased after changes from sitting to recumbent body position, whereas the subclavian artery pressure remained unchanged or decreased slightly. Changing from recumbent to sitting position was followed by a decrease in IOP, ophthalmic pressure, and subclavian artery pressure. Comparing the last measurement in the first position to the first value after change, it was found that the IOP alters by about 20%, the ophthalmic artery pressure by 15%, and the episcleral venous pressure by 50%. In all series a decrease in subclavian artery pressure was observed during the first 15 min. The mean pressure in the ophthalmic artery diminished in the series that changed from sitting to recumbent position, whereas it increased in the other series during the first 15 min. The episcleral venous pressure increased more than the corresponding IOP after changing to the recumbent position.

Blood Pressure↗
PubMedDate not supplied

[Automatic regulator of venous pressure and venous outflow in the perfusion system].

A scheme for automatic regulation of the venous pressure and venous blood outflow during extracorporeal circulation is proposed. The system consists of a photoelectric sensor placed on a tube led out of the major venous trunkline, a converter and an electromechanical eccentric clamp that compresses the venous trunkline, all of which secures stabilization of the controlled values.

Blood Circulation↗
PubMed1977

[Results and advantages of simultaneously measured peroperative arterial and central venous pressure].

Central venous pressure and intravasal arterial pressure have been followed up during different operations in 80 patients of different age and sex. At the same time we have determined an exact fluid balance and blood gas analysis pre-, intra- and postoperatively. These examinations had some interesting results. In our view the most important result is that the anesthetist gets more suitable informations about intraoperative blood volume therapy by continuous measuring of central venous pressure than by the continuous following up of intravasal arterial pressure which is practised very often to-day.

Age Factors↗
PubMed1976

Isofiltration capillary pressure and compartmental vascular resistances following elevation of venous pressure in subcutaneous tissue.

Isofiltration technique was used to measure the functional capillary pressure in 10 canine hindpaw (mainly subcutaneous tissue) preparations. With simultaneous determinations of arterial pressure, blood flow and venous pressure, the changes in total, precapillary and postcapillary resistances were assessed at different levels of venous pressure. When the tibial arterial pressure was 100 mm Hg. at an initial venous pressure of 5 mm Hg, the isofiltration capillary pressure averaged 12.8 mm Hg, the ratio of pre-to post-capillary resistance 9.9. The precapillary resistance accounted for 90.8% of the total vascular resistance. The isofiltration capillary pressures were 24.9 and 38.0 mm Hg, respectively when venous pressure was elevated to 20 and 35 mm Hg. Capillary pressure (Pc) was approximately related to venous pressure (Pv) by: Pc=0.82Pvm8. Upon elevation of venous pressure, the total and precapillary resistances were not significantly altered. The paw resistance vessels possess neither myogenic nor metabolic autoregulation. With increasing venous pressure, presumably due to passive distension of venules, the postcapillary resistance fell and the ratio of pre-to post-capillary resistance increased.

Animals↗
PubMed1977

Electrocardiogram, arterial and central venous pressure during laparoscopy under local anaesthesia.

Cardiovascular hazards of laparoscopy performed under local anaesthesia and with room air pneumoperitoneum are not well known. Therefore we have recorded electrocardiogram, arterial blood pressure and central venous pressure in 63 consecutive liver patients undergoing this procedure. Electrocardiographic changes were found in 34 cases, and consisted in transistory tachycardia and bradycardia, ectopic supraventricular and ventricular beats, ST segment depression and flattening of T wave. Blood pressure did not change significantly, but five patients had transitory hypotension during the procedure. Central venous pressure did not vary immediately after inflation, but a significant increase was found during the performance of laparoscopy and it was still observed after deflation. Our findings show that cardiovascular changes during laparoscopy under local anaesthesia are minimal, and that they are probably due to neurogenic factors.

Adult↗
PubMed1976

Mechanism of production of intestinal secretion by elevated venous pressure.

A study was carried out to elucidate the physiological mechanisms responsible for the intestinal secretion produced by venous pressure elevation. In dogs, measurements were made of the rate and composition of small intestinal secretion, rate of flow and composition of intestinal lymph, plasma composition, and mucosal water content, all in response to elevations of intestinal venous pressure. Venous pressure elevations above a threshold value of 30-35 cm H2O produce secretion at a rate of approximately proportional to the value of the pressure minus the threshold value. Above the threshold value, there were large increases in the rates of lymph flow and net sustained transcapillary filtration. These rates were also roughly proportional to the incremental venous pressure. It is concluded that intestinal secretion produced by elevated venous pressure is almost surely secretory filtration, a passive process with the driving force for secretion an increase in mucosal tissue fluid pressures to values of only some 4-6 cm H2O. The increased tissue fluid pressure not only provides the driving force but also produces an increase in the hydraulic permeability of the epithelium without which the driving force would be ineffective. The transepithelial channels are large enough to permit insulin to pass freely and even plasma protein to pass in large amounts, and hence are most probably intercellular. Secretory filtration probably represents a general pathophysiological response of transporting epithelia to elevated tissue fluid pressure. It is proposed that the threshold value for secretion and associated changes is explained by dilution of the tissue fluid protein colloid osmotic pressure in a small subepithelial, juxtacapillary compartment.

Animals↗
PubMed1979

[The effects of various anaesthetic techniques on central venous pressure during transurethral prostatectomy (author's transl)].

Central venous pressure was measured in 34 persons who had transurethral prostatectomy in general or regional anaesthesia. The aim of the investigation was to ascertain to what extent measurement of the central venous pressure as a parameter of blood volume can help towards the early diagnosis of hypervolaemia caused by the leakage of irrigation fluid into the patient's circulation. During general anaesthesia blood pressure and central venous pressure reached their maximum 10 minutes later and were significantly higher than was the case in regional anaesthesia. For detecting and preventing dangerous hypervolaemia during transurethral prostatectomy in general anaesthesia routine recording of the central venous pressure is recommended. The less severe reaction during regional anaesthesia on the circulation is probably attributable to a sympathicolytic effect and peripheral pooling. The early detection of the leakage syndrome is easier in the conscious patient.

Aged↗
PubMed1977

Effects of preanesthetic medication, anesthesia, and position of recumbency on central venous pressure in horses.

Central venous pressure (cvp) was recorded in horses before and after tranquilization and during halothane-maintained anesthesia in lateral or dorsal recumbency. The cvp was significantly decreased after administration of acetylpromazine, when compared with base line measurements and measurements taken after xylazine administration. After induction of anesthesia, cvp increased with time for 75 minutes, and values in lateral recumbency were significantly higher than those in dorsal recumbency.

Acepromazine↗
PubMed1979

Shifts in external iliac venous pressure under local and general anaesthesia. Their impact on the tactics of venous thrombectomy in iliofemoral thrombosis.

The authors measured the venous pressure in the iliofemoral segment in 12 patients in good general conditions, with a normal patency of the inferior caval vein, profound pelvic veins, and lower limb veins. Examination was performed with Claudy manometer. The resting venous pressure in the external iliac vein was 40--75 mm H2O = 3--5.5 mmHg. During Valsalva's manoeuvre the patients achieved an overpressure 250--1 100 mm H2O = 18--81 mmHg for 20 s. After induction of general anaesthesia and intubation, the anaesthesiologist produced an overpressure of 50 cm H2O in the patient's respiratory circuit for 20 s, but the venous pressure rose only to 90--175 mm H2O = 7-- mmHg. This rise is lesser with a high statistical significance than the overpressure produced in the Valsalva's manoeuvre. In the light of these results the authors discuss the tactics of venous thrombectomy. As a safe prevention of peroperative uplmonary embolism they regard either Valsalva's manoeuvre, carried out under local anaesthesia, or a tourniquet fixation of the clot head during the surgical intervention under general anaesthesia. The anaesthesiologist cannot prevent embolism by restriction of the venous return by producing an overpressure in the respiratory circuit of a patient under general anaesthesia.

Adult↗
PubMed1977

A comparison of central venous pressure and pleural pressure in supine dogs.

Respiration induced changes in central venous pressure were analyzed and compared with intrapleural pressure changes in dogs. During normal breathing intrapleural pressure changes were transmitted to the vena cava with distortion consisting of attenuation, addition of cardiac and mean pressure components, and a slight temporal delay. Attenuation and temporal delay increased in a regular manner as mean central venous pressure increased. Cardiac components could be removed by electronic filters. The presence of these distortions suggest the need for caution in interpreting intrapleural pressure changes from central venous pressure.

Animals↗
PubMed1976

Episcleral venous pressure and flow dynamics.

Episcleral venous pressure was measured by means of an air jet at different levels of occlusion of the measured vessel. This was repeated at different points in one branching venous plexus system. The results indicate that the most reliable estimate of the pressure is obtained at the pressure level at which the blood column becomes somewhat paler. Occlusion of the vessel causes a rise in venous pressure which may be considerable, especially in large veins.

Adult↗
PubMed1977

Capillary filtration coefficient in the canine hindpaw at different levels of venous pressure.

Capillary filtration coefficient (CFC) was determined in 12 dog's hindpaw preparations following elevation of venous pressure. From the quotient of slow component tissue volume change divided by the change in capillary pressure, the CFC averaged 0.027, 0.028 and 0.038 ml/min/mm Hg/100 gm respectively with an elevation of venous pressure from 0 to 15, 30 and 45 mm Hg. As compared with the previous determinations of CFC in the other tissues, the CFC of canine hindpaw was approximately in the same order of magnitude as that of the hindlimb, and was much less than those of the lung, intestine and heart. At venous pressure below 30 mm Hg, the CFC did not alter significantly with the level of venous pressure. This finding indicated that neither "stretched pore phenomenon" nor myogenic sphincter constriction occurred in response to a moderate increase in intramural pressure. The slight increase in CFC when venous pressure was elevated to 45 mm Hg suggested slight change in capillary permeability at high venous pressure, presumably due to the presence of stretched pore phenomenon.

Animals↗
PubMed1977

Effect of "vein pump" activation upon venous pressure and blood flow in human subcutaneous tissue.

The effect of "vein pump" activation upon superficial venous pressure and blood flow in human subcutaneous adipose tissue was studied in 6 normals and 2 patients with venous insufficiency. Blood flow in subcltaneous tissue was measured at the lateral malleolus by the local 133Xenon washout technique, with the subject placed in a supine position. During passive lowering of the leg blood flow decreased 50 per cent and total vascular resistance increased 136 per cent. Activation of the vein pump by continuously tipping the foot up and down caused a decrease in venous pressure of 5 mmHg in horizontal position. Venous pressure increased only by 8 mmHg when the leg was lowered during exercise. In this situation blood flow remained constant corresponding to an increase in vascular resistance of 42 per cent. However increasing venous pressure to 28 mmHg by venous stasis in the lowered leg during exercise caused an additional increase in vascular resistance of 82 per cent. In the patients with venous insufficiency exercise did not prevent the decrease in blood flow during lowering of the leg. Hence venous pressure elevation of 25 mmHg or more caused an additional increase in vascular resistance in subcutaneous tissue, "vasoconstrictor response". It is concluded that this "vasoconstrictor response" depends on a vasoconstrictor impulse transmission from veins to arterioles, veno-artertolar reflex.

Adipose Tissue↗