bluuebunny/crossref_metadata_2025_split huggingface dataset:
Density dependence of expiratory flow—a useful basis for lung function tests?
Authors: Sixt R. , Bake B. 
Published: April 2008

SummaryThe aim of this investigation was to study the density dependence of forced expiratory flow and the ability of tests based on density dependence to disclose smoking‐induced small airways dysfunction. The lung function of 212 systematically sampled men (mean age 40·3; range 30–48 years) was studied by recording flow‐volume curves during air or helium‐oxygen (HeOx) breathing and by the single breath N2‐test.Density dependence was expressed as the percentage increase in flow from air to HeOx when 50 and when 25% of the vital capacity (VC) remained to be expelled (dMEF50 and dMEF25).The mean dMEF50 in 59 healthy non‐smokers was 40% (range+7 to +72) and the mean dMEF25 24% (range ‐20 to +63). Density dependence apparently decreased with relative lung volume and also with increasing age.Despite the wide variation of density dependence in the reference group, dMEF50 was on average significantly reduced in smokers, and dMEF25 in ex‐smokers and subjects with symptoms such as cough and/or sputum production, wheezing unrelated to common colds and dyspnea when walking on level ground. However, only 8% of the smokers exhibited ‘abnormal’ density dependence (dMEF25 < (predicted value— 2RSD)) as compared to 11 and 33% for the forced expiratory volume in one second (FEV1) and dN2 (alveolar slope).If abnormal dN2 in the smoking group is taken to indicate smoking‐induced small airway dysfunction, then the ability of dMEF50 and dMEF25 to disclose such dysfunction is limited.
Plasma renin activity and oxygen content along the renal veins in hypertensive patients
Authors: Tidgren B. , Brodin U. 
Published: April 2008

Summary. Plasma renin activity (PRA) and oxygen content in three different locations in the renal veins were studied in 27 patients with suspected renin‐dependent hypertension or during post‐operative follow‐up investigations after renal artery reconstruction. A significant decrease in PRA was found along the right renal vein but not along the left one. The oxygen content simultaneously measured was lower in the central parts of both renal veins than most peripherally, more on the right side than on the left one, indicating dilution of renal venous blood.An erroneous ratio between renal vein PRA of the affected and the contralateral kidney was found in two of 17 patients with unilateral renal artery stenosis when sampling from a central position in the renal vein. This indicates that a peripheral position of the catheter is important when sampling for renal vein PRA.
The veno‐arteriolar reflex in free skin flaps
Authors: Zoltie N. , Young C. , Faris I. , Tan E. 
Published: April 2008

Summary. The veno‐arteriolar reflex was measured in 10 subjects in whom an area of denervated skin was present in the lower limb following free flap transfer of skin and subcutaneous tissue 3 weeks to 2 years previously. The vasoconstrictor response to dependency was measured in the skin of the flap, in adjacent innervated skin and after chemical dilatation of cutaneous vessels in the skin of the flap. This veno‐arteriolar reflex resulting in a reduction of blood flow of 30–40% was present and equal in both normal and denervated skin. The response was abolished by chemical vasodilatation.The results indicate that sympathetic innervation is not essential for the venoarteriolar reflex, and suggest that myogenic mechanisms may be more important than previously believed.
Arterio‐venous concentration difference of [51Cr]EDTA after a single injection in man. Significance of renal function and local blood flow
Authors: Rehling M. , Hyldstrup L. , Henriksen J. H. 
Published: April 2008

Summary. The present investigation was undertaken in order to study (1) the difference in arterial (Ca) and venous (Cv) concentration of [51Cr]EDTA (ethylenediaminetetra‐acetate) after a single intravenous injection, (2) the impact of different physiological variables on this difference, and (3) the error introduced in the measurement of renal plasma clearance and total plasma clearance by using venous blood samples instead of arterial.In 13 patients with GFR ranging from 29 to 150 ml min‐1, Ca was higher than Cv immediately after the injection. After mean 38 min (range 12–82 min) the two curves crossed, and 180–300 min post‐injection (p.i.) Cv was 5·9% higher than Ca (range 0·5–13·9%, P<0·001). The more reduced renal function, the smaller was the concentration difference. The areas under the arterial and the venous plasma concentration curves did not differ significantly at either 0–∞ or 0–300 min p.i., whereas the venous area 0–100 min p.i. underestimated the arterial area in the same period by 4·1% (P<0·05).In a computer simulation model, variation in the forearm capillary permeability–surface area product did not have any significant influence on the Cv–Ca difference, whereas the difference was very sensitive to even small changes in forearm blood flow within the physiological range.For measurement of renal plasma clearance it is recommended to use one long period: from the time of injection until 300 min p.i. or longer. If the clearance period is too short, the use of venous samples will overestimate the true renal clearance. Plasma clearance determined by venous and arterial blood samples does not differ significantly as long as the concentration is followed from the time of injection and a long period is applied. When simplified plasma clearance techniques are used, different results may be obtained from venous and arterial samples. The simplified techniques using venous blood samples—which usually include some empirical corrections—should be sufficiently reliable in daily clinical practice provided the forearm blood flow is reasonably high, e.g. exposure to cold should be avoided.
Chest pain and oesophageal pressure relationships in man following an intravenous bolus of adenosine
Authors: Melcher A. , Sylvén C. 
Published: April 2008

Summary. After titration of maximum tolerable i.v. bolus dose of adenosine, this dose was given to seven volunteers (20–42 years), instrumented with a three‐lumen oesophageal pressure catheter with recording sites at the levels of the stomach, the lower oesophageal sphincter (LOS) and the oesophagus. In addition to continuous pressure recordings, chest pain was estimated continuously by a 10‐graded category–ratio scale.Baseline resting pressures were 8·4 (1·9) mmHg in the stomach, 1·6 (1·7) mmHg in the oesophagus and 20 (2·6) mmHg in the LOS resulting in a net LOS pressure of 11 (± 1·3) mmHg. Following injection of adenosine which provoked transient chest pain with a rated maximum of 5·4 (1·0), resting oesophageal pressure did not change while net LOS pressure decreased to – 1·3 (1·9) mmHg (P<0·0001). Adenosine injection did not affect swallowing‐induced peristaltic contractions of the oesophagus and LOS although the peristaltic wave was delayed (P<0·05). Thus, chest pain evoked by adenosine cannot be caused by spastic oesophageal contractions. Adenosine may have a relaxing effect on the LOS but does not block its normal reactions to swallowing.
Fluorescein angiography and distal arterial pressure in patients with arterial disease of the legs
Authors: Wallin L. , Lund F. , Westling H. 
Published: April 2008

Summary. Fluorescein angiography (FA) of the foot soles was performed in 119 patients with arterial disease of the legs. Fluorescein was injected rapidly intravenously and sequential photographs were taken of the foot soles. Densitometric measurements were performed on three areas of each foot image: the big toe, the foot pad (just proximal to the little toe) and the heel. The relationships between different FA measurements and systolic arterial pressure in the ankle or the big toe were analysed.The appearance times of fluorescence correlated inversely with ankle pressure (P<0·001). The initial slopes of the fluorescence–time curves at all three sites of measurement correlated with ankle pressure (P<0·001). The initial slopes of fluorescence–time curves of the big toe and the foot pad correlated with toe pressure (P<0·001).In 12 patients effective arterial pressure was lowered by elevation of the feet, and in eight patients external pressure was applied to the foot by enclosing it in a box. The changes in FA evoked by these manoeuvres further strengthened the relationship between arterial pressures and FA measurements.We conclude that FA is a good method for evaluating circulation in the foot when neither ankle nor toe pressure is obtainable. In addition, FA may be useful when vascular disease is suspected in the presence of normal pressures, because the fluorescence distribution pattern was clearly abnormal in 11 of 16 such feet.
The effect of sympathetic blockade and cooling in Raynaud's phenomenon
Authors: Engelhart M. 
Published: April 2008

Summary.Nineteen patients with Raynaud's phenomenon (12 suffering from generalized scleroderma [GS] and seven from primary Raynaud's phenomenon [PR] and seven cold‐tolerant healthy women underwent a cooling challenge with combined body and finger cooling. Finger systolic blood pressure was measured at 30 and 15°C, before and after nervous blockade at the finger‐base with lidocain. Finger/arm blood pressure ratio (FBP/armBP) at 30°C was significantly lower in GS as compared to controls and PR, and it did not change after nervous blockade in any group. FBP/armBP at 15°C, decreased to zero in all patients with Raynaud's phenomenon and to median 0–67 in controls, prior to nervous blockade. After nervous blockade, in response to cooling, FBP/armBP at 15°C decreased significantly and was comparable in all groups.We conclude that the sympathetic nervous system seems to play an important part in provoking Raynaud's phenomenon in PR and most GS.
Effect of acquisition and analysis routines on gated blood pool measurements
Authors: Brodin L.‐Å. , Bone D. E. 
Published: April 2008

Summary. Results obtained from gated equilibrium blood pool (GBP) studies are not only dependent on intrinsic variations, but also on the way in which images are acquired and analysed. The aim of this study was to investigate factors which could affect left ventricular time‐activity curves.Temporal resolution was studied by comparing studies of 20 and 40 frames beat‐1. Forty frames per beat resulted in a mean left ventricular ejection fraction of 0.48 compared to 0.46 for 20 frames beat‐1. The mean difference of 0.02 was significant (P<0.01) as was the mean difference in maximum emptying rate (MER = 0.28, P<0.01) and in maximum filling rate (MFR = 0.38, P<0.01).No significant differences in ejection fraction (EF) values were found between acquisitions made in list and frame mode, but the mean differences for MER = 0.03 (P<0.05) and MFR = 0.01 (P<0.02) were significant. For patient repositioning and intra‐observer variations no significant differences were found.In patients with normal EF values (>0.5) no significant differences were found in the inter‐observer study. In patients with anterior myocardial infarction (AMI), significant differences were found in EF, MER and MFR (EF = 0.02, P<0.001; MER = 0.2, P<0.‐01; MFR = 0.24, P<0.01).Significant differences were found in all values when comparing a semi‐automatic method of evaluation with two automatic methods.In conclusion the results from this study suggest that acceptable reproducibility can be achieved in GBP studies, provided the method of analysis is not changed between studies.
Plasma levels of atrial natriuretic peptide at rest and during exercise in heart failure—influence of cardiac rhythm and haemodynamics
Authors: Berglund H. , Jensen‐Urstad M. , Theodorsson E. , Bevegård S. 
Published: April 2008

Summary. The relationship between plasma levels of immunoreactive atrial natriuretic peptide (ir‐ANP), arginine vasopressin (AVP), cardiac rhythm and different haemodynamic variables were studied at rest and during exercise in 16 patients with heart failure undergoing heart catheterization for clinically indicated reasons.Even though there was no significant relationship between pulmonary capillary wedge pressure (PCW) and ir‐ANP at rest (r= 0·39; P= 0·14) changes in these variables with exercise correlated well (r= 0·71; P= 0·002). Change in right atrial mean pressure, heart rate, mean arterial blood pressure or cardiac index did not significantly influence change in plasma levels of ir‐ANP. The correlation between PCW and AVP at rest (r= 0·92; P<<0·001) disappeared during exercise. Calculated ir‐ANP/PCW ratios decreased slightly during exercise, but were not influenced by initial atrial pressures or atrial fibrillation.These observations provide evidence for a similar responsiveness of ANP in patients with sinus rhythm and atrial fibrillation. The ability of rapid change in ANP plasma levels during exercise was preserved and proportional to changes in PCW over a wide pressure range in the studied patient group. This finding indicates that left atrium distension rather than right atrium distension is the major determinant for the release of ANP in patients with congestive heart failure. The observed rapid responsiveness of ANP to change in left atrial pressure may allow the hormone to modulate haemodynamic response during short periods of exercise.
Pulmonary vasodilatation and augmentation of right ventricular function following terbutaline infusion in severe chronic pulmonary disease
Authors: Eliasen K. , Ringsted C. , Munck O. , Hjortsø E. , Heslet L. 
Published: April 2008

Summary. Twenty patients with a median age of 61 years and a median forced expired volume in 1 s (FEV1) after bronchodilatating therapy of 0·55 1 were studied in order to measure the effect of intravenous terbutaline on bronchial tone, cardiac function, pulmonary haemodynamics, gas exchange, and oxygen transport capacity during rest and in 10 patients during exercise.Terbutaline infusion during rest resulted in an increase in heart rate from 84 to 103 beats min‐1 (P < 0·01), a decrease in mean systemic arterial pressure from 95 to 80 mmHg (P < 0·02), an unchanged mean pulmonary arterial pressure (18 mmHg), an increase in cardiac index from 2·89 to 3·86 1 min‐1 m‐2 (P < 0·01), an increase in right ventricular ejection fraction from 45 to 53% (P < 0·01), an increase in left ventricular ejection fraction from 63 to 67% (NS), an unchanged arterial oxygen tension, and an increase in calculated oxygen delivery from 533 to 638 ml O2 min‐1 m‐2 (P < 0·01). During exercise terbutaline infusion resulted in an increase in heart rate from 108 to 120 beats min‐1 (P < 0·05), a decrease in mean systemic arterial pressure from 117 to 106 mmHg (P < 0·01), a decrease in mean pulmonary arterial pressure from 29 to 22 mmHg (P < 0·01), an increase in cardiac index from 4·53 to 4·64 min‐1 m‐2 (NS), an unchanged arterial oxygen tension, and an increase in the calculated oxygen delivery from 834 to 856 ml O2 min‐1 m‐2 (NS).It was concluded that terbutaline augments right ventricular function: increases right ventricular ejection fraction and decreases right ventricular end‐diastolic volume, and further decreases pulmonary vascular resistance without decreasing arterial oxygen tension, and increases oxygen delivery in patients with chronic pulmonary disease during rest and exercise.
Reliability of impedance cardiography in measuring central haemodynamics
Authors: Mehlsen J. , Bonde J. , Stadeager C. , Rehling M. , Tangø M. , Trap‐Jensen J. 
Published: April 2008

Summary. The purpose of the study described here was to investigate the reliability of impedance cardiography (IC) in measuring cardiac output (CO) and central blood volume. Absolute values and changes in these variables obtained by impedance cardiography and by isotope‐ or thermodilution techniques were compared. The reproducibility of IC within the same day was compared with that of isotope dilution and the reproducibility in IC from day to day was derived. Finally, the effects of the readings of impedance tracings by different observers were quantified. The results are based on 270 measurements in 37 healthy subjects and in 25 unmedicated patients with ischaemic heart disease.We obtained significant correlations between absolute values y = 0·68x+1·48) and changes (y = 1·00x+0·0003) in CO measured by IC and isotope‐ or thermodilution. IC significantly overestimated absolute values of CO (P <0·001). We found a qualitative but no quantitative correlation between thoracic fluid volume measured by IC and central blood volume measured by isotope dilution.IC was highly reproducible both when studies were repeated within the same day (SD on differences in CO = 0·36 1 min1 for IC; SD on differences in CO = 0·30 1 min1 for isotope dilution) and on different days (SD on differences in CO = 0·45 1 min1). A low intra‐observer variability was found (SD on differences in CO = 0· 121min1).We conclude that impedance cardiography is reliable in measuring changes in cardiac output and thus suitable for repeated measurements in studies on the haemodynamic effects of physiological or pharmacological intervention. Impedance cardiography is sufficiently reliable for comparison of absolute values of CO between different groups of patients. We cannot recommend impedance cardiography for quantitative studies of central blood volume.
Local and central sympathetic reflex control of blood flow in skeletal muscle and subcutaneous tissue in normal man
Authors: Andersen E. B. , Boesen F. , Henriksen O. 
Published: April 2008

Summary. The effect of age and sex on relative changes in blood flow and vascular resistance in skeletal muscle and subcutaneous tissue during postural changes and during local increase in transmural pressure was studied in 33 healthy subjects.The intra‐individual variation was studied in five subjects. Blood flow was measured by the local 133Xenon wash‐out method. No relation to age or sex was seen in the centrally elicited sympathetic vasoconstrictor responses in subcutaneous tissue and skeletal muscle and in the locally elicited vasoconstriction in subcutaneous tissue. A small, but statistically significant, correlation to sex and age was found in the local sympathetic vasoconstrictor response in skeletal muscle. The age correlation was caused only by an attenuated response in the young subjects below 40 years of age and may be fortuitous. The intra‐individual variation was acceptably small.Based on the present results, a reduction in blood flow in skeletal muscle and subcutaneous tissue during centrally or locally elicited sympathetic vasoconstriction of 10% or less should be considered abnormal.The local 133Xenon wash‐out method is of value in examining patients suspected of dysfunction in the sympathetic part of the autonomic nervous system.
Use of non‐invasive finger blood pressure monitoring in the estimation of aortic pressure at rest and during the Mueller manoeuvre
Authors: Virolainen J. 
Published: April 2008

Summary. The aim of this investigation was to evaluate whether reliable estimates of aortic pressure can be derived using non‐invasive finger blood pressure monitoring. Finger blood pressure (Ohmeda 2300 Finapres device; Finapres, Englewood, CO) was compared with simultaneous ascending aortic pressure measured with a catheter‐transducer system both at rest and during acute negative intrathoracic pressure (the Mueller manoeuvre). Thirty‐eight patients aged 17–73 years were studied. All were undergoing routine diagnostic or therapeutic cardiac catheterization.Beat‐to‐beat values of systolic, diastolic and mean non‐invasive finger and invasive aortic blood pressure were measured at rest and factors which might have an influence on the difference between methods were examined. The mean finger‐aortic difference was +5 ± 14 mmHg for systolic, ‐2 ± 7 mmHg for diastolic, ‐5 ± 8 mmHg for mean and +6 ± 13 mmHg for pulse pressure. In multivariate linear regression analysis, the difference in systolic pressure was related to aortic systolic pressure (standardized coefficient β=‐0.33, P= 0.01), heart rate (β= 0.49, P<0.000), age (β=‐0.29, P<0.025) and height (β= 0.40, P<0.005). The linear regression equations to derive resting aortic pressures from the non‐invasive finger pressure readings had correlation coefficients between 0.83 and 0.87 and standard errors of estimate between 6 and 14 mmHg. During the Mueller manoeuvre, Finapres reproduced average pressure changes reliably compared with intra‐aortic pressure. Due to moderate inter‐individual variation in the finger‐aortic differences the correlation coefficients ranged from 0.83 to 0.93 and the standard errors of estimate from 3 to 6 mmHg.Non‐invasive finger blood pressure monitoring could be used to estimate central aortic mean and diastolic blood pressure fairly reliably at rest, but with respect to systolic pressure the variance in finger‐aortic difference was marked. The average intra‐aortic pressure changes caused by the Mueller manoeuvre were reliably reproduced by the Finapres device.
Renal effects of i.v. adenosine infusion in humans
Authors: Edlund A. , Sollevi A. 
Published: April 2008

Summary. The effects of systemic intravenous (i.v.) infusion of adenosine on renal blood flow and glomerular filtration in eight healthy, awake females have been examined.In conclusion, i.v. infusion of adenosine in healthy, awake subjects causes a minor increase in total renal blood flow and a marked reduction in glomerular filtration. This shows that adenosine also exerts a vasodilatory effect in the renal circulation, primarily on postglomerular arterioles. In addition, adenosine may produce an aldosterone‐like effect on salt excretion, and a reduction in renal oxygen consumption.Renal blood flow and glomerular filtration rate were measured as the clearance of para‐aminohippuric acid (PAH) and inulin, respectively. Following basal sampling adenosine was infused i.v. at successive rates of 60 and 80 μg kg‐1 min‐1 for 30 min at each rate.Plasma clearance of PAH showed a minor, but non‐significant, increase from 697 ±41 to 775 ±97 ml min‐1. However, the arterial plasma concentration of PAH decreased by 17±4% (P < 00.1), indicating that there was a small increase in renal blood flow. Inulin clearance was reduced from 123±14 to 88±11 ml min‐1 1.73 m‐2 (P < 0.01). The resulting filtration fraction was reduced from 18±1 to 11±1 (P < 0.001). The K+/Na+ excretion ratio increased from a basal value of 10±1 to 42±11 (P < 0.01) at the highest dose of adenosine, and renal oxygen consumption decreased from 17±2 to 9± 1 ml min‐x (P <0.001).