Femoral Vein Pressure Research Articles

A Novel Hemostatic Belt Allowing Ambulation Soon After Atrial Fibrillation Ablation.

We aimed to develop a hemostatic device with physiological evidence that allows ambulation soon after atrial fibrillation (AF) ablation. We measured right femoral vein pressure in 57 participants to clarify why groin post-venipuncture rebleeding often occurs during the transition from supine to sitting under compression bandage application and found that it increased more than threefold when raising the upper body (8.6 ± 4.1 to 27.6 ± 6.9 mmHg; P < 0.001). Based on that data, we created a novel hemostatic belt. Its capability test including 25 participants demonstrated that the belt gave much higher compression pressures on the right groin while sitting than the compression bandage (59.5 ± 14.9 vs. 8.1 ± 4 mmHg; P < 0.001), achieving pressures above the maximum femoral vein pressure in 92% of participants. A randomized trial comparing the belt with compression bandage in 74 AF patients demonstrated that the belt reduced time to ambulation without any rebleeding (340 [92.5-360] vs. 360 [360-360] min; P < 0.001) and satisfied more patients. The novel hemostatic belt provided a much higher compression pressure on the right groin during the sitting position than the conventional compression bandage, achieving a pressure above the maximum femoral vein pressure in 92% of the participants.

Correlation between venous pressure gradients and intravascular ultrasound in the diagnosis of iliac vein compression syndrome

ObjectiveThe objective of this study was to evaluate the correlation between venous pressure gradients (VPGs) and intravascular ultrasound (IVUS) for the diagnosis of caval-iliac venous obstructions in patients with advanced chronic venous insufficiency. MethodsFifty patients with advanced chronic venous insufficiency symptoms (Clinical, Etiology, Anatomy, and Pathophysiology class 3 to 6) were prospectively submitted to multiplanar venography (MV) with intravenous pressure measurements and IVUS. The patients' lower limbs were divided accordingly: group I, limbs with <50% obstruction on IVUS (n = 49); and group II, limbs with ≥50% obstruction on IVUS (n = 51). Receiver operating characteristic curves compared the diagnostic performance of the VPGs. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy assessed the performance of VPGs in categories to determine the presence of significant obstruction. Logistic regression assessed the capacity of the VPGs to identify significant obstruction. ResultsThe most frequent point of venous compression according to IVUS was the proximal left common iliac vein (70%; P < .05). Group II showed a greater prevalence of transpelvic (group I, 8.2%; group II, 74.5%; P < .001) and paravertebral collaterals (group I, 4.1%; group II, 45.1%; P < .001) on MV. The femoral vein pressures at rest and after reactive hyperemia as well as the femorocaval gradient after reactive hyperemia (FCG-rh) and the femoral gradient after reactive hyperemia were significantly higher in group II (P = .001, P < .001, P = .002, and P = .006). The FCG-rh and the femoral gradient after reactive hyperemia presented the best diagnostic performance among the VPGs (P = .004 and P = .007) in the receiver operating characteristic curve analysis, although no significant differences between them were found. All the gradients presented low values of sensitivity (<40%), negative predictive value (<60%), and accuracy (<30%). Logistic regression showed that FCG-rh was significantly independent of MV (OR, 8.1; P = .011) in identifying significant obstructions. ConclusionsThere is correlation between the VPGs and significant obstructions with IVUS. However, this correlation does not translate to a good diagnostic performance of these VPGs. Only the FCG-rh added significant information to MV in identifying significant caval-iliac vein obstructions.

CRRT in critically Ill children: Clinical profile from a tertiary care hospital in South India

Background : Continuous renal replacement therapy (CRRT) is a valuable tool in a pediatric intensive care unit (PICU), however the literature available from developing countries is scarce. Methods : Retrospective analysis of children who underwent CRRT during the past 1 year (June 2016 to May 2017). 24 sessions of CRRT was performed in 22 patients using Prismaflex® Baxter. Serum levels of urea, creatinine, and liver function tests were done in all patients. Activated clotting time (ACT) was monitored in all patients every 1 hourly till target ACT was achieved (180 – 220 seconds), thereafter every 4 hourly if the ACT continues in the target range. Unfractionated heparin was used for anticoagulation. Blood priming was done in patients with hematocrit less than 30% or in infants weighing less than 10 kg. Hemodialysis catheter (8.5Fr) was used in all patients, placed in the right internal jugular vein (IJV) under ultrasound guidance. Transthoracic echocardiography was used in all patients to confirm the position of the catheter tip within the right atrium. Central venous access in the femoral vein and arterial blood pressure monitoring was done in all patients as per unit protocol. Primary outcome measure was death during the procedure. Data collected were part of PRBC transfusion in pediatric ICU study and fluid balance study at JIPMER. Results : The median age of patients was 2 years (1 to 6 IQR). Mean bodyweight was 13.4 kg, 6.6 SD. Continuous venovenous hemofiltration (CVVH) was done in 5 patients (22.7%) and 17 patients (67.3%) were started on continuous venovenous hemodiafiltration (CVVHDF). Mortality during the procedure among the patients who underwent CRRT was 50% (n=11). Mean PRISM III score was 14. Out of 22 patients, 15 patients (68.7%) were on vasoactive medications at the time of initiation of CRRT. Median fluid overload (FO%) was 0.62 (0.45 to 1.62 IQR). Average time to start CRRT since PICU admission was 55 hours. The common indications were acute kidney injury with fluid overload (n=9), acute liver failure with hyperammonemia (n=3), organic acidemia with severe high anion gap acidosis (n=1), unknown poisoning with high anion gap acidosis (n=2), pigment nephropathy following wasp sting (n=1) and electrocution (n=1). CRRT along with venovenous extra corporeal membrane oxygenation (vv ECMO) (n=1) was done in a case of hemophagolymphohistiocytosis syndrome with ARDS. Effluent dose 35ml/kg/hour in all patients except in 2 cases of acute liver failure where the effluent dose was increased up to 42ml/kg/hour due to persistent hyperammonemia. CRRT with plasma exchange using P2 plasma filter was done with CRRT circuit modification in 2 cases of thrombocytopenia associated multiorgan failure (TAMOF). Mean duration of CRRT was (55 hours, SD 23.8). Maximum circuit life with systemic heparin as anticoagulant was 92 hours. Filter clotting and new circuit requirement was encountered in 6 patients (27.7%). Conclusion : CRRT can be used safely in critically ill children. The circuit life can be prolonged with serial ACT monitoring and titration of anticoagulation.

Intravenous pressure changes in patients with postthrombotic deep venous obstruction: results using a treadmill stress test

Essentials Little is known about the hemodynamic consequences of deep venous obstructive disease. We investigated pressure changes in 22 patients with unilateral postthrombotic obstruction. Common femoral vein pressure significantly increased after walking, compared to control limbs. Common femoral vein hypertension could explain the debilitating effect of venous claudication. Click to hear Dr Ten Cate's perspective on postthrombotic syndrome Background Little is known about the hemodynamic consequences of deep venous obstructive disease. Objectives The aim of this study was to investigate the hemodynamic effect of postthrombotic obstruction of the iliofemoral veins and to determine what pressure parameters differentiate best between limbs with post-thrombotic obstructive disease of the iliofemoral veins and those without obstruction. Methods Twenty-two participants with unilateral obstruction of the iliac and common femoral veins underwent a standardized treadmill test with simultaneous bilateral invasive pressure measurements in the common femoral vein and dorsal foot vein. Results Mean age was 42.8±11.9years and 86.4% of participants were female. Postthrombotic limbs showed a mean common femoral vein (CFV) pressure increase of 28.1±21.0mmHg after walking, compared with 2.1±6.2mmHg in control limbs (26.0mmHg difference; 95% confidence interval [CI], 17.1-34.9). Lessdifference was observed in the dorsal foot vein (net drop of 36.8±22.7mmHg in affected limbs vs. 48.7±23.1mmHg in non-affected limbs, 11.9mmHg difference; 95% CI, -1.3 to 25.0). Change in CFV pressure after walking yielded the best discrimination between affected and non-affected limbs (area under the receiver operated characteristic curve of 0.94 [95% CI, 0.85-1.00], compared with 0.57 [95% CI, 0.37-0.76] in the dorsal foot vein, P<0.001). Conclusions Common femoral vein pressure significantly increases during ambulation in patients with iliofemoral postthrombotic obstruction, which could explain the debilitating effects of venous claudication. This is an indication that patients with an iliofemoral obstruction may benefit from further treatment that resolves the deep vein obstruction. https://clinicaltrials.gov/show/NCT01846780.

Iliac-caval stenting in the obese

Chronic venous insufficiency (CVI) in the obese, often with severe clinical manifestations, is increasingly encountered in clinical practice. The association has drawn special interest as the pathophysiology may be different from that seen in the non-obese. The disease poses special management problems in the obese as traditional conservative measures are seldom effective. Iliac-caval venous stenting has been effective in CVI management but applicability in the obese raises concerns regarding stent compression, morbidity and efficacy. Results of iliac-caval stenting in 101 limbs of 87 patients are presented. Clinical features, venous test results, and outcome after stenting are reported with comparison to select relevant features in the non-obese limbs (n = 1513) that were stented over the same 11 year period. Bilateral clinical manifestations CVI were twice as common in the obese subset compared with the non-obese (28% vs 14% respectively, P = .0007), the incidence increasing with BMI. Resting and exercise femoral vein pressures were similar to the non-obese. Obstructive lesions of primary or postthrombotic origin similar to those seen in non-obese limbs were detected by intravascular ultrasound examination in 89% of limbs. Compression by increased intra-abdominal pressure associated with obesity was likely the mechanism of obstruction in 11% of the limbs. Iliac-caval venous stenting was found to be safe with no mortality (<30 days), low morbidity (deep venous thrombosis in 3%), high patency (86% cumulative at five years), and satisfactory clinical outcome. Sixty-eight percent and 46% of limbs showed cumulative improvement in pain and swelling respectively at 5 1/2 years after stenting, with 65% and 31% limbs achieving complete relief of these respective symptoms. Thirty of 45 limbs (58% cumulative) were free of dermatitis/ulcer at four years. The mechanism of venous obstruction in the obese is substantially similar to those in the non-obese. Primary or post-thrombotic lesions as seen in non-obese CVI cases are present in 89% of cases per IVUS examination. Compression of the venous outflow by adiposity/abdominal pressure may be a factor in 11%. Iliac-caval venous stenting is a satisfactory clinical option in the obese with severe CVI manifestations requiring speedy relief.

Compartment Pressure of the Rectus Sheath Accurately Reflects Intra-Abdominal Pressure in a Porcine Model

To investigate whether the compartment pressure of the rectus sheath (CPRS) reflects the intra-abdominal pressure (IAP) under various conditions of intra-abdominal hypertension (IAH) in a pig model. Prospective experimental study with in vivo pressure measurements. Institute for Clinical and Experimental Surgery, University of Saarland. Seven domestic male pigs (body weight 34.8+/-2.5 kg). Stepwise increase and decrease of IAP by means of CO(2) pneumoperitoneum. Continuous direct measurement of the IAP and correspondent indirect IAP measurement techniques including analysis of intravesical pressure (IVP), femoral vein pressure (FVP), and CPRS. Bland-Altman analysis comparing direct IAP measurement with correspondent CPRS showed good agreement for IAP between 12 mm Hg and 30 mm Hg (bias -0.5 mm Hg, lower and upper limits of agreement (LLA/ULA) -3.5/2.5 mm Hg). FVP (bias -0.3 mm Hg, LLA/ULA -2.3/1.6 mm Hg) and IVP (bias 0.4 mm Hg, LLA/ULA -2.1/2.9 mm Hg) demonstrated similar results compared with direct IAP measurement. Agreement was worse for all indirect IAP measurement techniques for IAP<12 mm Hg. CPRS accurately reflects IAP for IAP> or =12 mm Hg. Accuracy is similar to established indirect IAP measurement techniques.

The effects of dopamine on pulmonary artery pressure in dogs with endotoxic shock

To evaluate the values of dopamine in treating endotoxic shock by observing the changes in the pulmonary artery pressure (PAP) during the treatment. Twenty healthy dogs were randomly divided into four groups with 5 in each group. Endotoxic model was reproduced by injecting lipopolysaccharides (LPS) 1 mg/kg intravenously. Two hours later, normal saline (NS) 5 ml/h was intravenously given in model group, or dopamine 5, 10, 20 microg*kg(-1)*min(-1) was given in D5 group, D10 group, D20 group intravenously. Femoral artery pressure, femoral vein pressure and PAP were measured, and mean arterial pressure (MAP) and mean pulmonary artery pressure (MPAP) were recorded at 0, 5, 10, 30, 60, 120 minutes after infusion of NS or dopamine. Compared with the model group, all different concentrations of dopamine could elevate MAP, MPAP (P<0.05 or P<0.01). Compared with D5 group, the percentage of elevation of MAP of D10 group and D20 group was greater, and the percentage of elevation of MPAP of D20 group was greater than that in D5 group and D10 group (P<0.05 or P<0.01). The ratio of MAP/MPAP in each dopamine group was higher than that of model group, and the increase was more marked in the groups of higher concentrations (all P<0.05). MAP of endotoxic dog lowered obviously, while there was little change in PAP. After infusion of dopamine intravenously, both MAP and PAP are elevated. The increase in resistance of pulmonary microcirculation is the main reason for the elevation of PAP.

Are there changes in leg vascular resistance during laparoscopic cholecystectomy with CO2 pneumoperitoneum?

The prompt haemodynamic response to carbon dioxide insufflation during laparoscopic cholecystectomy suggests involvement of the sympathetic system. The aim of the present study was to examine if a change in vascular resistance in leg skeletal muscle could be an important mechanism behind the increased afterload. Furthermore, the arterio-venous differences of the catecholamines were measured in the leg before and during insufflation of carbon dioxide into the peritoneal cavity. Ten patients (ASA I) scheduled for laparoscopic cholecystectomy were included. After induction of anaesthesia, catheters were introduced percutaneously into the radial artery, the femoral vein and the cubital vein for pressure monitoring and blood sampling. The arterial blood flow in the legs was measured by mercury-in-Silastic strain gauge venous occlusion plethysmography. Vascular resistance in the right leg (LVR) was calculated from the formula: (MAP-FVP)/calf blood flow. Measurements were made before and 5 min after insufflation of pneumoperitoneum. Induction of pneumoperitoneum increased the heart rate (P < 0.05) and also increased mean arterial pressure and femoral vein pressure as well as the calculated leg vascular resistance (P < 0.01). Calf blood flow did not change significantly in either leg. Both arterial and venous noradrenaline concentrations were higher after insufflation (P < 0.01). In patients without heart or lung disease, pneumoperitoneum at an intra-abdominal pressure level of 11-13 mmHg increased the peripheral vascular resistance in the leg while the arterial blood flow in the leg was unaffected. Catecholamine levels increased, but were still low. Therefore, we suggest that the increase in peripheral vascular resistance is caused by increased myogenic activity in the resistance vessels secondary to increased arterial and transmural pressure rather than by increased neurogenic sympathetic activity.

Physiologic effects of externally applied continuous negative abdominal pressure for intra-abdominal hypertension.

To determine the ability of an externally applied continuous negative abdominal pressure device (CNAP) to reverse the effects of elevated intra-abdominal pressure on the central nervous and cardiovascular systems. Anesthetized, ventilated swine had catheters placed for measurement of intra-abdominal (IAP), intracranial (ICP), central venous, pulmonary artery, pulmonary artery occlusion, mean arterial, peak inspiratory, inferior vena cava, and femoral vein pressures. After the animals stabilized, baseline measurements were obtained. IAP was increased by incrementally instilling an isosmotic polyethylene glycol solution into the peritoneal cavity until it was 25 mm Hg above baseline. IAP was maintained at 25 mm Hg above baseline for 2 hours. CNAP was then applied for 2 hours. All parameters were remeasured 30 minutes after each increase in IAP, at 2 hours after attaining maximum IAP, and lastly at 2 hours after abdominal decompression. Cardiac index was maintained near baseline by volume expansion. Elevation of IAP to 25 mm Hg above baseline for 2 hours caused increases (p<0.05) in central venous pressure (10.3+/-0.9 to 15.2+/-1.7), inferior vena cava pressure (13.0+/-1.0 to 29.5+/-1.5), femoral vein pressure (13.5+/-0.5 to 33.3+/-1.3), ICP (10.6+/-1.5 to 21.0+/-1.5), and peak inspiratory pressure (18.3+/-0.3 to 34.2+/-1.0). The mean arterial pressure (106.3+/-3.5 to 125.8+/-3.4), pulmonary artery pressure (24.3+/-2.3 to 31.3+/-1.7), and pulmonary artery occlusion pressure rose (12.3+/-0.9 to 17.5+/-3.5), but not significantly. Cardiac index (3.3+/-0.5 to 3.4+/-0.4) remained essentially unchanged. CNAP significantly (p<0.05) decreased IAP (30.7+/-1.3 to 18.2+/-1.3), central venous pressure (15.2+/-1.7 to 12.4+/-2.1), inferior vena cava (29.5+/-1.5 to 19.2+/-1.3), and ICP (21.0+/-1.5 to 16.2+/-1.3). Pulmonary artery occlusion pressure (17.5+/-3.5 to 15.0+/-3.1) and peak inspiratory pressure (34.2+/-1.0 to 29.7+/-1.1) decreased, but not significantly. Acutely elevated IAP causes a significant increase in ICP and impaired cardiovascular and pulmonary function. Abdominal decompression remains the standard of care for abdominal compartment syndrome. However, in patients in whom an increased IAP does not require surgical decompression, the results of this study suggest that externally applied CNAP may be of value.

Conventional pneumoperitoneum compared with abdominal wall lift for laparoscopic cholecystectomy

We have compared, in a randomized study, conventional carbon dioxide pneumoperitoneum with abdominal wall lift in 25 patients undergoing laparoscopic cholecystectomy. Intra-abdominal pressure (IAP) (11 (SD 2) mm Hg vs 2.7 (9) mm Hg) (P < 0.01) and total amount of carbon dioxide used (40 (23) litre vs 9 (7) litre) (P < 0.001) were significantly less with abdominal wall lift. Pulmonary compliance was significantly greater (P < 0.01) in the abdominal wall lift group throughout operation. During the first 15 min of insufflation, arterial pressures were lower with abdominal wall lift (P < 0.05). In the conventional pneumoperitoneum group, femoral vein pressure increased (P < 0.01) and remained elevated for 3 h in the recovery room. Postoperative drowsiness was of significantly longer duration in the conventional pneumoperitoneum group than in the abdominal wall lift group (98 (46) min vs 13 (34) min) (P < 0.01). Postoperative nausea and vomiting and right shoulder pain occurred more often in patients with conventional pneumoperitoneum (P < 0.05). We conclude that the benefits of abdominal wall lift may be attributed to avoiding excessive carbon dioxide and high IAP.

Improvement of flow through arterial stenoses by drag reducing agents

The potential of drag reducing polymers (DRP) to selectively improve blood flow through clinically significant arterial stenoses was investigated. An artificial stenosis of the left common iliac artery in dogs decreased left femoral artery pressure by 25%. High-molecular-weight polyacrylamide (PA) or polyethylene oxide (PEO) were infused at a slow constant rate while we measured left and right common iliac artery blood flows and left and right femoral artery and vein pressures. As DRP were infused, left iliac artery flow ( Q L) increased early and then decreased to baseline values as flow began to increase in the right iliac artery. The peak increase in Q L was 24 ± 9% for PA and 46 ± 19% for PEO and occurred before right iliac artery flow ( Q R) increased. As additional polymer was infused, Q R increased to a maximum of 41 ± 12 and 131 ± 40% with PA and PEO, respectively. Femoral artery pressures and hindlimb resistances tended to decrease in both limbs but the only significant differences occurred in the right (nonstenosed) side when Q R was elevated. This study provides the first evidence that low concentrations of DRP might be capable of improving blood flow through stenotic blood vessels without altering flow in normal vessels. Although DRP might represent a new class of compounds that could be utilized in the treatment of cardiovascular diseases, the degree of variation in individual responses is a concern, the exact mechanism of action is unclear, and information on pharmacodynamics is lacking.

Acute Effect of Intraabdominal Pressure on Liver and Systemic Circulation

Intraabdominal and retroperitoneal hematoma due to abdominal trauma and surgery increase patients' intraabdominal pressure (IAP) and worsen their condition. In some cases, these hepatic and renal dysfunctions without primary shock. To clarify the pathogenicities, 7 mongrel dogs were subjected to the fol lowing experimental proctocol. Systemic blood pressure (BP), cardiac output (CO), portal vein flow (PVF), portal vein pressure (PVP), bile duct pressure (BDP), and femoral vein pressure (FVP), were measured at IAP levels of 0, 10, 20, 30, and 40 mmHg by infusing colloid sollution into the abdominal cavity. Analysis of the relationship between IAP and those factors showed the follow ing : (1) Although there was a poor relationship between IAP and BP, IAP had good correlation with PVP (p &lt; 0.001; (2) IAP had an inverse relation to CO (p &lt; 0.001) and PVF (p &lt; 0.02); and (3) FVP was the most sensitive indicator in monitoring IAP (p &lt; 0.05). These results suggest that the increased IAP should have an influence on liver function without producing shock, because of it effect on PVP and PVF.

Effect of long-term tilt on mechanical and electrical properties of rat saphenous vein.

Femoral vein pressure in adult male Sprague-Dawley rats kept in specially designed tubelike cages rose immediately from a control value of 2.9 +/- 0.2 (SE) mmHg to a gravity-induced sustained value of 5.9 +/- 0.2 mmHg on initiation of a 2-wk 45 degrees head-up tilt period. Femoral arterial pressure was not altered by tilting. In 2 wk mean external diameter, but not total wall thickness, of in vitro distal saphenous vein segments from tilted rats was increased approximately 30% above that of segments from nontilted controls at each of four successive 5-mmHg intralumenal pressure (IP) increments applied between 0 and 20 mmHg. Consequently, in tilted rats isobaric stress was increased 38% at low and 24% at high IP, whereas incremental distensibility was decreased at mid IP. Vascular smooth muscle (VSM) in tilted rat vein, but not artery, was hyperpolarized relative to controls both in vitro at normal physiological pressures [membrane potential (Em) = -58.2 +/- 0.8 vs. -52.4 +/- 0.8 mV, respectively] and in situ during local neural blockade (Em = -61.3 +/- 2.3 vs. -53.5 +/- 0.5 mV, respectively). The conclusion is that a moderate chronic elevation of IP in a vein results in hyperpolarization of its VSM and an elevation of its total capacity due to an as yet unexplained mechanism of physiological adaptation.

Increased vascular resistance during complement-activated plasma infusion in swine.

To investigate the acute effects of complement activation on blood flow, we infused complement-activated plasma into the femoral artery of the isolated hindlimb of 19 anesthetized swine. Femoral artery blood flow decreased abruptly, was lowest at 1 min of the infusion, and thereafter slowly increased despite continued infusion. There was no significant change in femoral artery pressure or femoral vein pressure, confirming an acute increase in vascular resistance. Control infusion of heat-decomplemented-activated plasma caused no change in pressure or flow. Slope of the femoral artery pressure-flow relationship during maximal vasodilation with adenosine was significantly lower after infusion of complement-activated plasma, confirming a persistent increase in vascular resistance. Neither the acute nor the persistent increase in vascular resistance was prevented by alpha-adrenergic blockade with phentolamine or granulocytopenia produced by cyclophosphamide. We conclude that complement-activated plasma infusion in the femoral circulation causes an abrupt increase in vascular resistance that persists during pharmacologically maximal vasodilation, is not due to alpha-mediated vasoconstriction, and is not altered by severe granulocytopenia.

Femoral vein pressure measurements for evaluation of venous function in patients with postthrombotic iliac veins.

Fifty patients with postthrombotic disease were examined by phlebography and by bilateral femoral vein pressure measurements. The degree of obstruction to venous flow was best evaluated by measuring the pressure elevation and pressure difference after exercise and the time required for these parameters to return to pre-exercise levels; pressures during rest and exercise were less conclusive indicators of obstruction. Good correspondence was found between femoral vein pressure and the severity of postthrombotic symptoms, while phleboraphy provided largely morphologic, rather than functional, information. We, therefore, consider it important to determine femoral vein pressure during and after exercise to evaluate the significance of postthrombotic iliac vein disease.

Streptokinase treatment of deep venous thrombosis and the postthrombotic syndrome. Follow-up evaluation of venous function.

The conditions of 35 patients with deep venous thrombosis treated with streptokinase were reevaluated after a mean of 29 months with clinical examination, venous plethysmography, foot volumetry, phlebography (28 patients) and femoral vein pressure measurement (24 patients). At follow-up, 25 patients (71%) had symptoms and 22 (63%) had signs of venous insufficiency. Plethysmography was abnormal in 29 patients (83%) and foot volumetry in 25 (72%). Only two (6%) of the patients had normal plethysmography and foot volumetry and were free from symptoms and signs. No leg ulcer or severe postthrombotic syndrome was found. Phlebography showed that no patient had a normal deep venous system. Six of earlier thrombotic iliac veins (38%) and femoral veins 14 (48%), respectively, remained occluded. Increased femoral venous pressure, more pronounced during and after exercise, was found when iliac vein was diseased. Our results emphasize the importance of functional evaluation of the patient with a postthrombotic leg.

Venous changes in renal hypertensive rats: the role of humoral factors.

In order to investigate the role of circulating humoral substances in the pathogenesis of venous changes in experimental hypertension, an attempt was made to induce venous changes in rats in parabiosis with two-kidney Goldblatt hypertensive rats. Sham-operated normotensive rats in parabiosis were used as controls. Venous pressure-volume curves were obtained in the pump perfused vascular beds of the lower body of rats by recording the femoral vein pressure rise during rapid infusion of fluid into the inferior vena cava. The water, sodium and potassium content of veins also was measured. Compared to values in normotensive control rats (n = 11), the venous pressure-volume curves of two-kidney Goldblatt hypertensive rats in parabiosis with unoperated rats (n = 13) were shifted in the direction of the pressure axis (p &lt; 0.01), indicating decreased venous capacity. Venous pressure-volume curves in rats in parabiosis with two-kidney Goldblatt hypertensive rats (n = 13) and in rats in parabiosis with sham-operated rats (n = 10) were similar. The venous wall water, sodium and potassium content in two-kidney Goldblatt hypertensive rats (n = 8) and in their unoperated parabiotic mates (n = 8) was increased (p &lt; 0.05) in comparison to that of sham-operated rats in parabiosis (n = 10). These experiments provide evidence for the role of circulating humoral substances in the pathogenesis of abnormal venous wall composition but not of decreased venous capacity in renal hypertensive rats.

Role of sympathetics in the response to acute venous occlusion.

The effect of venous ligation and subsequent blockade of alpha receptors on hindlimb venous pressure, vascular resistance, oxygen extraction and carbon dioxide removal was evaluated in mongrel dogs with use of constant-flow perfusion of the extremity bed. Perfusion, metatarsal vein, femoral vein, and central vein pressures, and changes in paw and thigh circumference were recorded in mongrel dogs in which the hindlimb was perfused at a constant flow. Arterial, metatarsal venous, and femoral venous blood gases were drawn and analyzed for arteriovenous oxygen and carbon dioxide differences. Measurements were repeated following extensive ligation of veins and after subsequent alpha-receptor blockade with Dibenzyline. Findings indicated that ligation of extremity veins resulted in an active increase in total limb resistance upstream from the ligation, and an increase in volume of the limb. Following alpha-adrenergic blockade with Dibenzyline, limb volume increased and oxygen extraction decreased below control levels. The reflex constriction following ligation of veins protected against the detrimental effect of excessive accumulation of fluid in tissue spaces.

Cardiovascular effects of intraperitoneal insufflation with carbon dioxide and nitrous oxide in the dog.

Cardiovascular changes caused by intraperitoneal insufflation with CO2 or N2O were measured in 15 mongrel dogs. Moderate progressive increases in intra-abdominal pressure (to 40 mm Hg) with either gas produced increases in mean arterial, right atrial, pleural, and femoral-vein pressures. Cardiac output and inferior vena caval flow were momentarily increased following the commencement of insufflation. However, both flows decreased precipitously as insufflation pressure was increased. At an intra-abdominal pressure of 40 mm Hg cardiac output and inferior vena caval flow were reduced more than 60 per cent in most cases. Peripheral resistance increased by approximately 200 per cent. Upon sudden release of abdominal pressure cardiac output and inferior vana caval flow increased but then returned to pre-insufflation values within seconds. Directly measured right atrial pressure increased with increasing insufflation pressure, but calculated transmural right atrial pressure decreased with the increase in intra-abdominal pressure. Insufflation with CO2 produced significant increases in PaCO2. However, cardiostimulatory effects due to elevated blood CO2 levels were not seen. The data from this study indicate that intraperitoneal insufflation produces serious hemodynamic alterations which are manifested by low cardiac output and elevated total peripheral resistance. In addition, directly measured right atrial pressure cannot be used clinically as an indicator of venous return to the heart since it reflects a composite of pleural and intra-abdominal insufflation pressure. (Key words: Anesthetics, gases, nitrous oxide; Carbon dioxide, intraperitoneal; Surgery, intraperitoneal insufflation; Heart, function, intraperitoneal insufflation.).

VENOUS ENGORGEMENT AND INTRAOSSEOUS HYPERTENSION IN OSTEOARTHRITIS OF THE HIP

1. In fifteen patients with unilateral osteoarthritis of the hip bilateral measurements of the intraosseous pressure of the femoral neck and determination of femoral vein pressure were done simultaneously. These pressure examinations were followed by bilateral intraosseous phlebography of the proximal part of the femur. 2. In a second series of fifteen patients the intraosseous pressures of the femoral head and neck were measured simultaneously before operation for osteoarthritis. 3. The pressure in the femoral vein was equal on the two sides. The intraosseous pressure in the femoral neck was always higher in the arthritic hip than on the unaffected side. In hips with osteoarthritis the pressure in the femoral head was higher than the pressure in the neck. 4. Intraosseous phlebography indicated a state of intramedullary venous engorgement in osteoarthritis. The normal channels for venous drainage from the femoral head and neck were not visible in the phlebographs from the arthritic side. Instead, drainage took place through descending intramedullary vessels to the trochanteric region and down into the femoral shaft. The emptying of intraosseous contrast material from the arthritic hip was delayed. 5. The phlebographs indicated that the abnormally high intraosseous pressure observed in osteoarthritis is caused by a high resistance to flow across the cortex of the proximal part of the femur. 6. The aching rest pain typical of severe osteoarthritis was noted only in patients with intraosseous femoral neck pressure above 40 millimetres of mercury, an indication that this type of pain is caused by intramedullary hypertension. The decrease of arteriovenous pressure difference, caused by increase of resistance to venous outflow, is probably accompanied by disturbances of nutritive flow. This "venous ischaemia" may play an important role for the structural changes of cancellous bone in osteoarthritis.