Femoral Pressure Research Articles

Comparison of femoral and carotid blood pressure during laparoscopy in piglets

PurposeThe impact of a capnoperitoneum on the known blood pressure (BP) difference of the upper and lower limb was studied in piglets. MethodsEleven German Landrace piglets (body weight, 4.3-7.4 kg; mean body weight, 6.2 kg) were studied. Arterial lines were placed in the right carotid and right femoral artery for pressure monitoring. Intraabdominal pressure levels were increased in steps of 6 mm Hg up to 24 mm Hg. ResultsWe found that elevated intraabdominal pressures up to 24 mm Hg did not change the preexisting systolic BP difference between the carotid and femoral arteries. Systolic femoral artery pressure constantly remained 5% higher than its carotid counterpart. In addition, mean and diastolic values were not affected. ConclusionsArterial BP measurements recorded at the legs of piglets when abdominal pressure is increased by up to 24 mm Hg can be used for intraoperative assessment of systemic arterial BP.

The influence of the femoral force application point on tibial cementing pressure in cemented UKA: an experimental study

Aseptic loosening is the major cause for implant failure in cemented unicompartmental knee arthroplasty (UKA). Central positioning of the femoral pressure during the tibial cementation process is recommended to achieve equal pressure and a good cementation result. The aim of this study was to verify the central position of the femoral force application point (FFAP) at 45° flexion of the knee and to investigate the influence of ligament tension and cement penetration pressure (CPP) for UKA. Cemented Oxford UKAs were performed in 24 human legs. CPP and ligament tension forces (LTF) were measured. The FFAP was measured in a standardised manner in relation to the tibial implant length on lateral digital X-rays. The FFAP at 45° of knee flexion is located at 53.5 % and is not significantly different from the FFAP at 0° (p = 0.768). The CPP shows mean values at the anterior portion of 13.97 kPa (SD 16.11), at the implant keel of 24.34 kPa (SD 25.21) and at the posterior portion of 36.58 kPa (SD 26.51). The LTF shows a mean value of 194.35 N (SD 83.77). The central position of the FFAP for the investigated cemented UKA with single radius femoral component at 45° flexion of the knee could be confirmed. A flexion angle of <45° does not influence the position of the FFAP significantly. More than 45° of flexion should be avoided because the FFAP shifts backwards significantly and may cause increased pressures posteriorly and therefore tilting of the component occurs during the cementation process.

An invasive but simple and accurate method for ascending aorta–femoral artery pulse wave velocity measurement

Introduction. Pulse wave velocity (PWV) is an emerging predictor in the assessment of cardiovascular risk in diseased and healthy populations. We suggest a novel method for the accurate measurement of PWV. Method. PWV is calculated from pulse transit time using two separate pulse recordings over a known distance. 8F sheaths were placed in the right femoral arteries and routine coronary angiographies were performed with 5F diagnostic catheters. Ascending aorta pressures were measured with right diagnostic catheter tip in the ascending aorta and synchronous femoral artery pressures were measured with the sheath in the femoral artery. The distance between the two pressure sites was calculated as follows: total length of the right diagnostic catheter−length of the catheter outside the sheath−Sheath length. Results. We evaluated the PWV measured using the catheter method in 24 subjects. PWV correlated positively and independently with age (p = 0.004), coronary artery disease (p = 0.04), ascending aorta systolic pressure (p = 0.006), femoral artery systolic pressure (p = 0.008), ascending aorta pulse pressure (p = 0.003) and femoral artery pulse pressure (p = 0.04). In coronary artery disease patients, the mean PWV value was significantly higher than in patients with normal coronary arteries (12.61 ± 6.31 m/s vs 7.58 ± 2.26 m/s p = 0.04). Conclusion. We describe a novel and accurate but invasive method for measurement of PWV. Our results may serve as a reference for non-invasive assessment of aorta–femoral artery PWV.

Role for NGF in augmented sympathetic nerve response to activation of mechanically and metabolically sensitive muscle afferents in rats with femoral artery occlusion

Arterial blood pressure and heart rate responses to static contraction of the hindlimb muscles are greater in rats whose femoral arteries were previously ligated than in control rats. Also, the prior findings demonstrate that nerve growth factor (NGF) is increased in sensory neurons-dorsal root ganglion (DRG) neurons of occluded rats. However, the role for endogenous NGF in engagement of the augmented sympathetic and pressor responses to stimulation of mechanically and/or metabolically sensitive muscle afferent nerves during static contraction after femoral artery ligation has not been specifically determined. In the present study, both afferent nerves and either of them were activated by muscle contraction, passive tendon stretch, and arterial injection of lactic acid into the hindlimb muscles. Data showed that femoral occlusion-augmented blood pressure response to contraction was significantly attenuated by a prior administration of the NGF antibody (NGF-Ab) into the hindlimb muscles. The effects of NGF neutralization were not seen when the sympathetic nerve and pressor responses were evoked by stimulation of mechanically sensitive muscle afferent nerves with tendon stretch in occluded rats. In addition, chemically sensitive muscle afferent nerves were stimulated by lactic acid injected into arterial blood supply of the hindlimb muscles after the prior NGF-Ab, demonstrating that the reflex muscle responses to lactic acid were significantly attenuated. The results of this study further showed that NGF-Ab attenuated an increase in acid-sensing ion channel subtype 3 (ASIC3) of DRG in occluded rats. Moreover, immunohistochemistry was employed to examine the number of C-fiber and A-fiber DRG neurons. The data showed that distribution of DRG neurons with different thin fiber phenotypes was not notably altered when NGF was infused into the hindlimb muscles. However, NGF increased expression of ASIC3 in DRG neurons with C-fiber but not A-fiber. Overall, these data suggest that 1) NGF is amplified in sensory nerves of occluded rats and contributes to augmented reflex sympathetic and blood pressure responses evoked by stimulation of chemically, but not mechanically, sensitive muscle afferent nerves and 2) NGF likely plays a role in modulating the muscle metaboreflex via enhancement of ASIC3 expression in C-fiber of DRG neurons.

Aortic Calcification and Femoral Bone Density Are Independently Associated with Left Ventricular Mass in Patients with Chronic Kidney Disease

BackgroundVascular calcification and reduced bone density are prevalent in chronic kidney disease and linked to increased cardiovascular risk. The mechanism is unknown. We assessed the relationship between vascular calcification, femoral bone density and left ventricular mass in patients with stage 3 non-diabetic chronic kidney disease in a cross-sectional observational study.Methodology and Principal FindingsA total of 120 patients were recruited (54% male, mean age 55±14 years, mean glomerular filtration rate 50±13 ml/min/1.73 m2). Abdominal aortic calcification was assessed using lateral lumbar spine radiography and was present in 48%. Mean femoral Z-score measured using dual energy x-ray absorptiometry was 0.60±1.06. Cardiovascular magnetic resonance imaging was used to determine left ventricular mass. One patient had left ventricular hypertrophy. Subjects with aortic calcification had higher left ventricular mass compared to those without (56±16 vs. 48±12 g/m2, P = 0.002), as did patients with femoral Z-scores below zero (56±15 vs. 49±13 g/m2, P = 0.01). In univariate analysis presence of aortic calcification correlated with left ventricular mass (r = 0.32, P = 0.001); mean femoral Z-score inversely correlated with left ventricular mass (r = −0.28, P = 0.004). In a multivariate regression model that included presence of aortic calcification, mean femoral Z-score, gender and 24-hour systolic blood pressure, 46% of the variability in left ventricular mass was explained (P<0.001).ConclusionsIn patients with stage 3 non-diabetic chronic kidney disease, lower mean femoral Z-score and presence of aortic calcification are independently associated with increased left ventricular mass. Further research exploring the pathophysiology that underlies these relationships is warranted.

Enhancing Proximal Femoral Pressure during Cemented Stem Insertion

Poor proximal femoral pressures during a cemented primary hip replacement may compromise proximal fixation and cause early aseptic loosening. Occlusion of the calcar, during stem insertion, achieves a uniform and sustained rise in the proximal intra-medullary pressure, which should enhance cement penetration into bone and improve long-term survival of the prosthesis. 54 Exeter stems were cemented into femoral moulds prepared from plaster of Paris. Pressure transducers were connected to the proximal, middle and distal zones of the mould. After cement insertion, stems were implanted with occlusion of the calcar by either nothing, a thumb placed medially or an Exeter horse-collar. 18 stems each were inserted into Palacos-R at 3½-4 minutes and 4-4½ minutes after mixing and Simplex-P 6-6½ minutes after mixing and the intra-medullary pressures were measured. Data were subjected to regression analysis using SPSS. Proximal and distal intra-medullary pressures were significantly higher (P < 0.01-0.001) with proximal occlusion in all cements. The highest pressures were achieved with Palacos-R at 4-4½ minutes after mixing, with proximal thumb occlusion. Stem insertion into Palacos-R at 3½-4 min. or 4-4½ min. after mixing, gave higher pressures than into Simplex-P regardless of the method of occlusion. With Simplex-P, there was a trend to higher proximal intra-medullary pressures with the horse-collar. Occluding the calcar during stem insertion into cement achieves and sustains high intra-medullary pressures in both the proximal and distal femur. The highest pressures are obtained with stem insertion into Palacos-R at 4-4½ minutes after mixing, with proximal thumb occlusion. A horse-collar achieves slightly higher pressures with Simplex-P.

Hemodynamics in the Cardiac Catheterization Laboratory of the 21st Century

There has been a striking evolution in the role of the cardiac catheterization laboratory over the past decades.1 In the 1950s and 1960s, hemodynamic assessment in the cardiac catheterization laboratory was essential for understanding the physiology and pathophysiology of patients with cardiovascular diseases. With the development of surgical interventions to treat patients with valvular and congenital heart disease, it became necessary for the cardiac catheterization laboratory to provide an accurate hemodynamic assessment, laying out a therapeutic road map. Nearly all patients who had open heart surgery underwent a complete hemodynamic catheterization before surgery. In the 1980s and 1990s, the evolution of 2-dimensional echocardiography and Doppler echocardiography provided an alternative noninvasive approach for the assessment of both cardiac anatomy and hemodynamics in patients with structural heart disease.2 By measuring blood flow velocities noninvasively, Doppler echocardiography was able to provide information on volumetric flow, intracardiac pressures, pressure gradients, and valve areas, as well as diastolic filling of the heart. Furthermore, noninvasive studies could be repeated easily, allowing the practitioner to follow the progress of his/her patient's condition longitudinally. At the same time, there was growing emphasis on coronary angiography for defining epicardial coronary disease with the subsequent development of interventional approaches for coronary disease with catheter-based therapies. As the major focus in the catheterization laboratory shifted to the diagnosis and treatment of the patient with acute and chronic coronary artery disease, the hemodynamic assessment of patients with structural heart disease was left to the noninvasive echocardiographic laboratory. As a consequence, many cardiac catheterization laboratories provided neither the training nor the expertise to assess hemodynamics properly. However, the advent of procedures such as balloon valvotomy, percutaneous valve implantation, and septal ablation has revived interest in structural heart disease and provided the invasive cardiologist with an armamentarium to treat patients who previously …

Blood flow velocity and vascular resistance during passive leg exercise in the critically ill patient

Passive range of motion exercise is a very common physical therapy treatment for patients admitted to an intensive care unit. However is the knowledge scarce regarding its impact on blood circulation in the extremities. The objective of this study was therefore to investigate the effect of passive range of motion on arterial peripheral leg blood flow velocity (BFV) and vascular resistance. A cross-sectional consecutive study of twelve patients admitted to an intensive care unit and twelve healthy age- and gender-matched controls was conducted. Passive range of motion was performed in one leg by a physical therapist. Blood flow velocities and resistance index in the common femoral artery (CFA), blood pressure and heart rate were measured before, directly after and at rest after passive range of motion. No changes were seen in BFV or resistance index in the patient group or the control group. No changes were found in blood pressure or heart rate in the patient group. In the control group, changes were found in systolic and mean blood pressure, with a higher pressure before passive range of motion. The controls had lower BFV and higher resistance index than the patients when comparing the groups. The conclusion of this study including twelve patients is that passive range of motion does not alter BFV or resistance index in the CFA in comatose and/or sedated critically ill patients.

Neutralization of NGF Attenuates Augmented Sympathetic Nerve Responses to Activation of Chemically Sensitive Muscle Afferents in Rats with Femoral Artery Occlusion

Arterial blood pressure and heart rate responses to static contraction of the hindlimb muscles are greater in rats whose femoral artery is previously ligated than in control rats. Also, the prior findings demonstrate that nerve growth factor (NGF) is amplified in dorsal root ganglion (DRG) neurons of occluded rats. NGF has been reported to sensitize responsiveness to mechanical and chemical stimuli via thin fiber afferent nerves. Thus, the present study was first to examine the role for NGF in engagement of the augmented sympathetic and pressor responses to muscle contraction and passive tendon stretch after 24 hrs of femoral artery ligation. The data showed that femoral occlusion‐augmented blood pressure response to contraction was significantly attenuated by the prior administration of NGF antibody into the hindlimb muscles. The effects of NGF neutralization were not seen as the sympathetic and pressor responses were evoked by stimulation of muscle mechanically sensitive afferent nerves with muscle stretch in occluded rats. In addition, chemically sensitive afferent nerves were stimulated by lactic acid injected into the arterial blood supply of the hindlimb muscles after the prior injection of NGF antibody, demonstrating that the reflex responses to lactic acid were significantly attenuated. Moreover, immunohistochemistry was employed to examine the number of DRG neurons that project C‐fiber and A‐fiber. The data showed that distribution of DRG neurons with thin fiber phenotypes was not notably altered as NGF was infused into the hindlimb muscles. However, NGF increased expression of acid sensing ion channel subtype 3 in DRG neurons with thin C‐fiber, but not A‐fiber. Overall, these data suggest that NGF increased in sensory nerves of occluded rats is likely engaged in augmented reflex sympathetic and blood pressure responses evoked by stimulation of chemically, but not mechanically sensitive muscle afferent nerves.

Treatment for coarctation of the aorta: where are we and where do we go from here?

Department of Paediatric Cardiology, Evelina Children’s Hospital, Guy’s & St Thomas NHS Foundation Trust, Westminster Bridge Road, London, SE1 7EH, UK Tel.: +44 207 188 4562 thomas.krasemann@gstt.nhs.uk Coarctation of the aorta Coarctation of the aorta is typically a stenosis of the descending aorta in the area of the ductus arteriosus Botalli and caused by ductal tissue in the aortic wall. Once the duct constricts postnatally, this tissue constricts as well and leads to the typical posterior shelf, which is visible on echocardiography. Aortic coarctation is found in approximately 1:3000 newborns and, if left untreated, reduces the life expectancy to 34 years on average [1]. Associated congenital heart disease such as bicuspid aortic valves, hypoplastic aortic arch, ventricular septal defects and others are frequently observed [2]. Clinical signs are weak or absent femoral pulses and blood pressure difference from upper to lower limbs. A heart murmur may be audible on the left sternal border, but it is more important to listen between the scapula. While in neonates echocardiography alone is sufficient to establish the diagnosis, as the treatment is typically surgical, later in life further imaging such as MRI or computed tomography scans will allow adequate therapeutical planning.

Association between markers of collagen turnover, arterial stiffness and left ventricular hypertrophy in chronic kidney disease (CKD): the Renal Research Institute (RRI)-CKD Study

Markers of collagen turnover have not been well studied in the context of cardiovascular disease in patients with chronic kidney disease (CKD). We investigated the associations between serum markers of collagen turnover [N-terminal procollagen type 3 propeptide (PIIINP) and carboxy-terminal telopeptide (C1TP)] and both pulse wave velocity (PWV) and left ventricular mass index (LVMI) in a CKD cohort. The study included 242 patients (mean age 60 ± 15 years, 53% males, 80% Caucasian, CKD Stages 3-5) from the Renal Research Institute (RRI)-CKD Study. Serum PIIINP and C1TP levels were analyzed by radioimmunoassay. PWV was obtained by applanation tonometry from carotid and femoral pressure wave contours. LVMI was measured by echocardiography. Statistical analyses included Pearson's correlations and multiple linear regression. Both PIIINP and C1TP values were significantly higher in more advanced stages of CKD (P < 0.05). A positive correlation was demonstrated between PWV and LVMI (r = 0.25, P = 0.0018), persisting after adjustment for potential confounders (partial r = 0.27, P = 0.0009). PIIINP correlated with PWV (r = 0.16, p = 0.029) and LVMI (r = 0.16, P = 0.0018), while C1TP correlated with LVMI (r = 0.18, P = 0.013) but not with PWV (r = 0.12, P = 0.09). In multivariable analysis adjusting for race, diabetes, estimated glomerular filtration rate (eGFR) and renin-angiotensin-aldosterone system inhibitors, only PWV (β = 0.45, P = 0.0017) but not LVMI (P = 0.09) remained significantly associated with serum PIIINP. Our results demonstrate the association of PIIINP (but not C1TP), a circulating biomarker of collagen synthesis with arterial stiffness (but not with LVMI) in a CKD cohort, independent of eGFR. This suggests that altered collagen turnover may play a role in the pathogenesis of arterial stiffness in CKD.

Cartilage Pressure Distributions Provide a Footprint to Define Female Anterior Cruciate Ligament Injury Mechanisms

Background Bone bruises located on the lateral femoral condyle and posterolateral tibia are commonly associated with anterior cruciate ligament (ACL) injuries and may contribute to the high risk for knee osteoarthritis after ACL injury. The resultant footprint (location) of a bone bruise after ACL injury provides evidence of the inciting injury mechanism. Purpose/Hypothesis (1) To analyze tibial and femoral articular cartilage pressure distributions during normal landing and injury simulations, and (2) to evaluate ACL strains for conditions that lead to articular cartilage pressure distributions similar to bone bruise patterns associated with ACL injury. The hypothesis was that combined knee abduction and anterior tibial translation injury simulations would demonstrate peak articular cartilage pressure distributions in the lateral femoral condyle and posterolateral tibia. The corollary hypothesis was that combined knee abduction and anterior tibial translation injury conditions would result in the highest ACL strains. Study Design Descriptive laboratory study. Methods Prospective biomechanical data from athletes who subsequently suffered ACL injuries after testing (n = 9) and uninjured teammates (n = 390) were used as baseline input data for finite element model comparisons. Results Peak articular pressures that occurred on the posterolateral tibia and lateral femoral condyle were demonstrated for injury conditions that had a baseline knee abduction angle of 5°. Combined planar injury conditions of abduction/anterior tibial translation, anterior tibial translation/internal tibial rotation, or anterior tibial translation/external tibial rotation or isolated anterior tibial translation, external tibial rotation, or internal tibial rotation resulted in peak pressures in the posterolateral tibia and lateral femur. The highest ACL strains occurred during the combined abduction/anterior tibial translation condition in the group that had a baseline knee abduction angle of 5°. Conclusion The results of this study support a valgus collapse as the major ACL injury mechanism that results from tibial abduction rotations combined with anterior tibial translation or external or internal tibial rotations. Clinical Relevance Reduction of large multiplanar knee motions that include abduction, anterior translation, and internal/external tibial motions may reduce the risk for ACL injuries and associated bone bruises. In particular, prevention of an abduction knee posture during initial contact of the foot with the ground may help prevent ACL injury.

Response to Pulsatile Flow Analysis of the Femoral Artery

We thank Mc Loughlin and Mc Loughlin1 for their interest in our recent article2 and their important suggestions for investigating the potential association between the Pulsatility Index (PI) of the femoral flow velocity waveform and pressure pulse parameters. We reanalyzed our data obtaining the PI by dividing the forward-to-reverse peak velocity amplitude by the mean velocity. As a result, the mean femoral PI was 8.6±3.7 for the 138 subjects. The PI was significantly correlated with age ( r =0.28; P =0.001) and femoral vascular resistance ( r =0.72; P <0.001). However, it had no significant correlation with the aortic pulse wave velocity, aortic augmentation index, or aorta-to-femoral pulse …

Model of cardiac arrest in rats by transcutaneous electrical epicardium stimulation

Objective To establish a new model of cardiac arrest (CA) in rats by transcutaneous electrical epicardium stimulation. Methods Two acupuncture needles connected to the anode and cathode of a stimulator were transcutaneously inserted into the epicardium as electrodes. The stimulating current was steered to the epicardium and the stimulation was maintained for 3 min to induce CA. Cardiopulmonary resuscitation (CPR) was performed at 6 min after a period of nonintervention. Results CA was successfully induced in a total of 20 rats. The success rate of induction was 12/20 at the current intensity of 1 mA; and reached 20/20 when the current intensity was increased to 2 mA. After the electrical stimulation, the femoral blood pressure quickly dropped below 25 mm Hg and the arterial pulse waveform disappeared. The average time from the electrical stimulation to CA induction was 5.10 (±2.81) s. When the electrical stimulation stopped, 18/20 rats had ventricular fibrillation and 2/20 rats had pulseless electrical activity. CPR was performed for averagely 207.4 (±148.8) s. The restoration of spontaneous circulation (ROSC) was 20/20. The death rate within 4 h after ROSC was 5/20, and the 72-h survival rate was 10/20. There were only two cases of complications, a minor muscle contraction and a minor lung lobe injury. Conclusion The model of CA in rats induced by transcutaneous electrical epicardium stimulation is a stable model that requires low-intensity current and has fewer complications. This model may provide another option for experimental research of CA induced by malignant arrhythmia (especially VF).

Estimation of vascular properties using noninvasive measurements and a mathematical model of the systemic arteries

The estimation of vascular properties is useful for physiological and clinical assessment.PURPOSEThe purpose of this study was to estimate vascular properties under different physiological conditions using noninvasive measurements and a mathematical model of the arterial circulation.METHODSBlood pressure waveforms were recorded by applanation tonometry at the radial and femoral arteries in 21 individuals under control conditions, during a cold pressor test, and after administration of sublingual nitroglycerin. A mathematical model of the arterial circulation was used to predict femoral artery pressure wave from measured radial artery pressure wave. Three model parameters were adjusted to minimize the difference between estimated and measured femoral pressure.RESULTSResistance vessel diameter profile, arterial resistance, blood volume, and aortic pressure depended significantly on the perturbation given (ANOVA, p&lt;0.01), but cardiac output and total arterial compliance did not (p&gt;0.05). The root mean square difference between the predicted and measured femoral waveforms was 6.8 ± 4.5 mmHg.CONCLUSIONSVascular mechanical properties estimated under different conditions had realistic values. Some but not all estimated quantities showed significant variation when physiological conditions were altered.Supported by the University of Delaware Research Foundation.

Coronary Computed Tomography Angiography for Screening of an Asymptomatic Population: Too Much or Too Soon?

Coronary Computed Tomography Angiography for Screening of an Asymptomatic Population: Too Much or Too Soon?

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.

Femoral cement pressurisation for hip arthroplasty in previously fixated hips: An experimental study

Introduction It is common to use a cemented total hip replacement following failed hip screw fixation of a fractured femoral neck; this solution, however, is complicated by the presence of the holes that are left in the femur when the screws are removed. These holes can allow cement to leak out while being pressurised. The aim of this study was to look at the cement femoral pressures proximally and distally in a sawbone model with pre-drilled holes to assess if the commonest surgical technique of occluding the holes with fingers could maintain the cement pressure high enough. Materials and methods We used eight synthetic proximal femurs, four with dynamic hip screw holes drilled in them on the lateral surface (“drilled femurs”) and four with no holes (“undrilled femurs”). We used pressure sensors positioned in holes drilled in the proximal and distal parts of the medial surface to measure the pressure in the cement as it was being delivered and pressurised into the femur canal. The tests were conducted while the femur was clamped at its distal end and, in the case of the drilled femurs, while the screw holes were occluded manually. Results We found that on the proximal side, the peak cement pressure in undrilled femurs was significantly greater than in drilled femurs ( p = 0.006). On the distal side, the difference in peak cement pressure between the two study groups was not significant ( p = 0.22). At both the proximal and distal positions, the time over which the cement pressure exceeded both 5 and 100 kPa was significantly longer in undrilled femurs than in drilled femurs ( p < 0.05). Conclusion Our results show that it is difficult to fully occlude the drill holes completely with finger tips, especially when using pressurised cement. There are significant differences in the peak cement pressures between drilled and undrilled femurs with possible consequences for patients undergoing total hip replacement.

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.