bluuebunny/crossref_metadata_2025 huggingface dataset:
Miniature Silicon diode matrix‐detector for in vivo measurement of 133Xenon disappearance in the canine myocardium following local tissue injection
Authors: Svendsen J. H. , Rasmussen H. B. , Damgaard Y. , Bojsen J. , Haunsø S.
Published: April 2008

Summary. After local tissue depositioning of 133Xenon (133Xe) the regional washout is usually registered by a Nal(Tl) detector. The residual radioactivity of 133Xe is usually measured at its 81 keV photopeak. However, using small Silicon (Si) photodiodes it is feasible to measure only the low‐energy activity in the X‐ray energy range. In the myocardium of open chest dogs 133Xe washout measurements by a matrix of Si diodes composed in a 4×4 array and a conventional NaI(TI) detector were carried out simultaneously. Fourteen separate pairs of measurements were performed in 3 dogs. When the Si‐diodes in the matrix were selected individually in accordance to the position with reference to the diode with maximum count rate or pooled, comparisons could be made between the corresponding washout rate constants measured by the reference detector. In the correlation between the rate constants the intercepts with the y axis were not significantly different from zero allowing the correlation lines to be fitted through (0.0). The slope of the correlation line was close to unity. The registration of the low‐X‐ray energy of 133Xe by the Si‐detectors is an alternative to the conventional high energy activity recording appearing from the gamma‐energy of the photopeak. The detector matrix concept allows elimination of motion artefacts and indicator distribution in the myocardial tissue. Due to the uniformity and low cost of Si‐diodes the perspective may be the introduction as a disposable transducer useful during cardiac surgery for example.
Thigh composition in young and elderly men determined by computed tomography
Authors: Overend T. J. , Cunningham D. A. , Paterson D. H. , Lefcoe M. S.
Published: April 2008

Summary. Computed tomography (CT) was used to quantify components of the thigh in young (n= 13) and elderly (n= 11) men. Cross‐sectional areas (CSA) of the total limb, total muscle plus bone, quadriceps compartment, hamstring compartment and bone were measured at each of five scan sites along the length of the thigh. Non‐muscle tissue (NMT) areas within the muscle compartments were measured using changes in density based on Hounsfield units. Skin plus subcutaneous fat areas and quadriceps and hamstring lean muscle areas were calculated by subtraction. Geometric formulae were used to calculate related volumes for each thigh component. Volumes were also predicted from regression equations employing thigh length and component CSA from single mid‐limb CT scans. The results showed that while total thigh CSA was not different in elderly men, they had significantly smaller total muscle plus bone (13‐0%), and quadriceps (26.4%), and hamstring (17.9%) muscle areas. The elderly men also had significantly greater CSA for skin plus subcutaneous fat (37‐6%), and for NMT in the quadriceps (59.4%) and hamstring (127.3%) muscle compartments. These results suggest that comparisons of relative leg muscle strength between young and elderly men may be misleading due to the decrease in actual muscle tissue associated with ageing. Appropriate quantification of muscle size and CSA must be carried out before such comparisons can be meaningful.
Heart rate during haemorrhagic shock
Authors: Jacobsen J. , Secher N. H.
Published: April 2008

Summary. In a prospective study, heart rate and mean arterial pressure were related to estimated blood loss in 34 consecutive patients aged 23–92 years during resuscitation from haemorrhagic shock. Eighteen patients with a blood loss of less than 31 (1.9 [0.9‐3.0] 1) (median and range), corresponding to 34 (16–46) % of estimated blood volume, had a heart rate of 83 (60–160) beats min‐1 and a mean arterial pressure of 62 (35–73) mmHg. In 16 patients with a blood loss of more than 3 1 (4.0 [3.3–5.0] 1) corresponding to 89 (35–100) % of the estimated blood volume, heart rate was 120 (110–160) beats min‐1 (P<0.05) and mean arterial pressure 52 (0–70) mmHg (P< 0.05). Six patients died due to severe bleeding (3.1 [2.5‐5.0] 1) with a heart rate of 129 (110–160) beats min‐1 and a mean arterial pressure of 40 (0.70) mmHg. It is concluded that reversible hypovolemic shock is associated with a relatively low heart rate (approximately 80 beats min‐1) and that tachycardia (approximately 120 beats min‐1) is associated with profound bleeding. Hypovolemic shock with tachycardia may represent a transition to an irreversible stage.
Assessment of the composition of major body regions by dual‐energy X‐ray absorptiometry (DEXA), with special reference to limb muscle mass
Authors: Fuller N. J. , Laskey M. A. , Elia M.
Published: April 2008

Summary Dual‐energy X‐ray absorptiometry (DEXA) has been used to assess and compare the composition of whole body and major body regions in 12 female (weight, 56.9 ± 6–2 kg; BMI, 17.25 kg m‐2) and 16 male (weight, 73.1 ± 9–6 kg; BMI, 20.28 kg m‐2) healthy subjects. Standard deviations (and % coefficients of variation) of the differences between repeated measurements of fat ranged from 0.11 kg (9.0%) for arms to 0.42 kg (30%) for whole body; for arm bone mineral, 0.01 kg (2.0%), and for fat‐free soft tissue of the whole body, 0.42 kg (0.8%). Limb muscle mass was estimated using a new theoretical model of body composition, and the corresponding precision ranged from 015 kg (3.8%) to 0.27 kg (1.5%) for arms and total limb muscle mass, respectively.

Proportions of each region consisting of fat were greater in females than in males (range, 20.31% vs. 16.18%), respectively, but the ratio of trunk to leg fat was lower (34:49% vs. 46:38%, respectively). Regional proportions of bone were similar between the sexes (all in the range 2.9–5.6%, for both females and males).

Mean total limb muscle masses were 14.2 kg (arms, 2.8 kg; legs, 11.4 kg) for females and 22.2 kg (arms, 4.8 kg; legs, 17.4 kg) for males, which were 33.6% and 36.0% of fat‐free mass, respectively. The correlation coefficients between limb muscle (DEXA) and other indices of muscle mass were: for DEXA vs. total body potassium, 0.90 (SEE 1.1kg muscle mass) to 0.94 (1.6 kg); and for DEXA vs. anthropometry, 0.43 (1.2 kg) to 0.85 (1.3 kg). Those for limb volume (DEXA) vs. anthropometric volume, 0.91 (0.78 1) to 0.94 (1.91 1).

It is concluded that DEXA enables the valid and reproducible estimation of fat, fat‐free soft tissue, bone, and limb muscle mass.
Biomagnetic multi‐channel systems. Principles and application in cardiology
Authors: Reichenberger H. , Schneider S. , Moshage W. , Weismüllen P.
Published: April 2008

Summary The non‐invasive measurement of the extremely weak magnetic fields generated by heart and brain is motivated by the possibility of obtaining quantitative diagnostic information about electric function. Magnetic signals (MCG, MEG) are significantly less influenced by body tissue than the corresponding electric signals (ECG, EEG). Measurement of biomagnetic signals is performed by superconducting sensors consisting of pickup coils and SQUIDs (superconducting quantum interference device) operating in liquid Helium. For clinical investigations a biomagnetic multi‐channel system (KRENIKONR) has been designed. It uses a flat array of 37 magnetic field sensors and is operated inside a shielded room. Evaluation of biomagnetic signals by use of simple source and body models and in combination with anatomical data from 3D MR‐ or CT‐images yields sequences of locations of electrical function with a spatial resolution of some millimeters and a time resolution better than one millisecond. More than three years of clinical studies have demonstrated the value of the method primarily in cases with localized functional pathologies. In cardiology this is pathologies of the cardiac conductive pathway, ectopies, and arrhythmias. Validation has been performed by catheter stimulation in volunteers, and by catheter mapping and nuclear medical methods in patients. Extension of modelling and evaluation to cases with distributed activity, e.g. ventricular excitation, is under investigation.
A model approach for calculating the net capillary filtration rate during venous occlusion
Authors: Kolari P. J.
Published: April 2008

Summary. The venous occlusion method is commonly used to measure the net capillary filtration rate, calculated from the slope of the increasing volume curve of the limb at a given time. However, this technique does not take variation in the rate of venous filling into account. In the present study, a model of sum of two cumulative exponential functions was developed to describe the venous filling phase and the increase in interstitial fluid volume due to the net capillary filtration rate. The model was tested on 15 normal subjects and eight patients with post‐thrombotic venous insufficiency. The cumulative exponential model gave a good description of the changes in volume that occur during venous occlusion. The model also enabled determination of the net CFR at the same phase of the maximal venous capacity.
Effect of nifedipine on splanchnic and pulmonary vascular capacitance
Authors: Risøe C. , Smiseth O. A. , Rootwelt K. , Sire S. , Simonsen S.
Published: April 2008

Summary. This study examines the hypothesis that nifedipine may increase splanchnic vascular capacitance and thus change the distribution of blood between the splanchnic and pulmonary circulation in heart failure patients. Relative regional blood volumes were determined by equilibrium blood pool scintigraphy during a 10 min baseline period and for 30 min after nifedipine 20 mg sublingually, with simultaneous recordings of systemic and pulmonary arterial pressures, hepatic venous wedge pressure, and cardiac output. Eight patients with ischaemic heart failure received nifedipine. Four patients served as controls. Nifedipine reduced mean arterial pressure and systemic vascular resistance in every patient. There were no significant changes in the relative blood volumes of the intestinal, hepatic, or splenic regions or in hepatic venous wedge pressure (reflecting portal venous pressure), suggesting unchanged splanchnic vascular pressure‐volume relationship. Nifedipine caused a 6.3±l.0% increase in relative pulmonary blood volume and a slight increase in pulmonary vascular distending pressure from 16.1±2.9 mmHg to 17.5±2.8 mmHg (P < 0.05), suggesting that the increase in pulmonary blood volume was passively mediated. In conclusion, nifedipine did not change splanchnic vascular capacitance, but caused a small increase in pulmonary blood volume, which probably was a passive response to increased distending pressure.
Cardioinhibitory‐vasodepressor response to head‐up tilt without hypoxaemia or myocardial ischaemia
Authors: Matzen S. , Secher N. H.
Published: April 2008

Summary. We evaluated whether hypoxaemia and/or myocardial ischaemia are of importance for development of the bradycardic hypotensive phase (cardioinhibitory‐vasodepressor syncope) of central hypovolaemia. Arterial blood gas variables and a twelve‐lead electrocardiogram (ECG) were followed during head‐up tilt in seven men. During tilt, before presyncopal symptoms appeared, mean arterial pressure (MAP) increased (from 67±7 to 78±6 mmHg) (meanæ) as did heart rate (HR) (61 ±4 to 99±8 beats min‐1) and total peripheral resistance (TPR) (ll±lto17±l mmHg min l‐1) (P < 0.01), while cardiac output (5.9±0.5 to 4.6±0.6 1 min‐1) and central venous pressure (CVP) (4.2±0.4 to l.3±0.7 mmHg) decreased (P < 0.01). After 40±7 min of head‐up tilt presyncopal symptoms appeared together with a decrease in MAP to 48 ±7 mmHg, HR to 71±11 beats min‐1 and TPR to 9±2 mmHg min l‐1 (P < 0.01). Arterial oxygen tension was not changed and there was no ST‐segment depression of the ECG. The results indicate that during central hypovolaemia decreases in HR and TPR are elicited during normoxaemia and without electrocardiographic signs of myocardial ischaemia.
Platelet activation in mental stress
Authors: Naesh O. , Haedersdal C. , Hindberg I. , Trap‐Jensen J.
Published: April 2008

Summary. Platelets are known to become activated in vivo by different stressful stimuli such as surgery and dynamic exercise. Mental stress has been shown to increase platelet aggregability. Platelet activation is thought to be of major importance in atherogenesis and cardiac fatalities. In order to clarify further stress‐induced platelet activation with special reference to the period after the stress, we studied eight young, healthy volunteers during and for 1 h after a mental stress test (Stroops Colour Word Conflict Test). Using highly standardized techniques, we have measured platelet aggregability ex vivo and the platelet release products beta‐thromboglobulin, platelet factor 4 and serotonin in plasma. As markers of the stress response we measured cyclic‐AMP in plasma, heart rate, cardiac output and blood pressure. The stress test induced a significant cardiovascular response with increases in heart rate, blood pressure, and cardiac output and as a measure of adrenergic activity an increase in cyclic AMP in plasma during the test. Platelet aggregability was unaffected during the test but decreased following the stress. During the first hour following the test and release products beta‐thromboglobulin and serotonin increased significantly in plasma. We conclude that platelets are activated during mental stress and that this activation involves a post‐stress release of vasoactive compounds from platelets.
The effect of opioids on inspiratory muscle fatigue during inspiratory resistive loading
Authors: Wanke T. , Lahrmann H. , Formanek D. , Zwick B. , Merkle M. , Zwick H.
Published: April 2008

Summary. The effect of opioids on inspiratory muscle function under high mechanical load is still unknown. Even less clear is the extent to which opioids influence the shift of the electromyographic power spectrum of the inspiratory muscles to lower frequencies during ventilatory stress. We studied seven healthy subjects breathing against high inspiratory threshold loads until exhaustion while keeping the minute ventilation constantly high. We compared runs with and without administration of 0.2 mg kg‐1 of morphine sulphate intramuscularly; two subjects were given 30 mg morphine sulphate so that we could study the effect of higher opioid concentration. The endurance time (Tlim), the diagraphragmatic electromyogram (EMG), the transdiaphragmatic pressures (Pdi) and the ventilatory effort sensation were analysed. Morphine did not have any effect on Tlim or on the effort sensation elicited by the inspiratory resistance in both concentrations. Analysing the spectral shifts of the diaphragmatic EMG, we did not find any significant difference in the decrease of the centroid frequency between drug and control runs. Furthermore, the activation pattern of the diaphragm and the intercostal muscles, evaluated from the percentage contribution of oesophageal and gastric pressures on the transdiaphragmatic pressure swings, did not change following the administration of morphine. Our study shows that morphine does not change the function of the inspiratory muscles during high‐resistive breathing. Morphine does not affect the electromyographic power spectrum of the diaphragm during those resistive breathing runs, either. This points out that during stressful ventilatory situations, the shift of the electromyographic power spectrum is attributed to a peripheral (muscular) event consequent to muscle fatigue and not to the elaboration of endogenous opioids.
Planar 201T1 scintigraphy in ischaemic heart disease: a critical re‐evaluation of qualitative and quantitative data analysis
Authors: Pedersen F. , Rabøl A. , Sørensen S. S. , Høilund‐Carlsen P. F. , Madsen J. Kyst , Efsen F. , Sandøe E.
Published: April 2008

Summary. The aims of the present study were to examine the observer agreement of qualitative (visual) and quantitative (computer‐assisted) analysis of planar 201T1 imaging and to compare the diagnostic values of these methods in the detection of infarcted and exercise‐induced ischaemic myocardium. The study population comprised of 119 patients (aged 24–77 years) referred consecutively for stress thallium scintigraphy for either diagnostic reasons (n= 42, 35%) or for further evaluation of known coronary artery disease (CAD) (n= 77,65%).

The interobserver agreement was low with the qualitative method and significantly higher with the quantitative method: Kappa‐values 0.29‐0.39 vs. 0.80‐0.92, P < 0.00001. Sensitivity and specificity for the detection of previous Q‐wave infarct was significantly higher with the quantitative method (94% and 94%) compared to the qualitative method (77% and 74%), P < 0.01. The corresponding predictive values of a positive and a negative test were 96% and 92% vs. 80% and 70% (P < 0.01).

In 86 patients in whom coronary angiography was performed the two methods did not differ significantly regarding sensitivity, specificity and predictive values for the diagnosis of reversible ischaemia or rather CAD. However, when 22 patients with a maximal exercise heart rate < 80% of the predicted target heart rate were excluded the sensitivity was increased with both techniques and was significantly higher with the quantitative method.

We conclude that qualitative image analysis has an unacceptably low reproducibility and that quantitative image analysis increases the diagnostic value of 201T1 scintigraphy considerably in both the detection of previous infarcts and, provided a sufficient exercise level is achieved, in the disclosure of reversible myocardial ischaemia.
Comparison between reference values for 201Thallium uptake and washout from the myocardium after exercise and after dipyridamole
Authors: Munck O. , Madsen P. V. , Kelbaek H. , Godtfredsen J.
Published: April 2008

Summary. A slow washout of 201Thallium has a high diagnostic and prognostic value for coronary artery disease. The aim of the present work was to contribute with reference data on 201T1 uptake and washout from the myocardium. With a quantitative method using circumferential profiles and interpolative background subtraction we performed 201T1 myocardial imaging in two groups of subjects with a low probability of coronary artery disease. Washout in per cent is defined as (1‐D/I) 100, where D is the delayed uptake rate and I the initial uptake rate. In group A (n=16) myocardial hyperaemia was induced by maximal exercise, in group B (n=15) by intravenous infusion of dipyridamole. In group A, the mean washout was 52%, and in group B it was 34% (P < 0.001). The delayed uptake rate D was significantly higher after dipyridamole, 58.4 cps, than after exercise, 44.5 cps (P < 0.05). There was no significant difference in I between the two groups. The findings regarding D and I explain that the washout is slower after dipyridamole than after exercise, as the mean D/I ratio was 0.48 in group A and 0.66 in group B (P < 00.1).
Changes in plasma volume and baroreflex function following resistance exercise
Authors: Ploutz L. L. , Tatro D. L. , Dudley G. A. , Convertino V. A.
Published: April 2008

Summary. The dynamics of change in plasma volume (PV) and baroreflex responses have been reported over 24 h immediately following maximal cycle exercise. The purpose of this study was to determine if PV and baroreflex showed similar changes for 24 h after resistance exercise. Eight men were studied on 2 test days, 1 week apart. On 1 day, per cent change (%Δ) in PV was estimated at 0,3, and 6 h after resistance exercise using haematocrit and haemoglobin. Baseline PV was measured 24 h after exercise using Evans blue dye. The carotid baroreceptor‐cardiac reflex response was measured before, and 3,6,9,12, and 24 h post‐exercise. Each subject performed six sets of the bench press and leg press with 10 repetitions per set with a load that induced failure within each set. On a control day, the protocol was used without exercise. Plasma volume did not change during the control day. There was a 20% decrease in PV immediately post‐exercise; the recovery of the PV was rapid and complete within 3 h. PV was 20% greater 24 h post‐exercise than on the control day. There were no differences in any of the baroreflex measurements. Therefore, it is suggested that PV shifts may occur without altering baroreflex sensitivity.
Breath‐by‐breath determination of inspiratory occlusion pressure
Authors: Larsson H. , Hellstrom L. G. , Linnarsson D.
Published: April 2008

Summary. In order to determine the influence of breath‐by‐breath measurement of inspiratory occlusion pressure (P0.1) on the pulmonary ventilation, the respiratory timing and the central inspiratory activity as reflected by P0.1per se, nine healthy males were studied as they breathed in a valve assembly including an externally controlled occlusion valve. A new technique was used, terminating occlusions at a preset inspiratory threshold pressure and determining P0.1 from linear regression of the mouth pressure curve. Subjects were studied at rest and during light exercise, with the occluding function (threshold pressure) on or off during alternating periods. Breath‐by‐breath variability of P0.1 was of the order of 30%. We found no detectable influence of breath‐by‐breath short‐lasting inspiratory occlusions on tidal volume and ventilation. However, mean inspiratory flow was slightly increased due to a shortened inspiratory duration at rest and during light exercise. Also, raising the threshold pressure for occlusions from 69 to 147 Pa (0.7 to 1.5 cm H2O) resulted in a 20% increase of P0.1. We conclude that breath‐by‐breath measurement of P0.1 is a feasible technique, and that the slightly shortened inspiratory duration and the increased P0.1 with increased threshold pressure may not necessarily be expressions of a true stimulation of the central inspiratory activity.
Right ventricular pressure‐volume relations in chronic lung disease
Authors: Schrijen F. V. , Redondo J. , Henriquez A. H. , Chabot F.
Published: April 2008

Summary. Thirty‐four patients with chronic lung disease in stable condition were studied at supine rest (RS), at rest with the legs raised (LR), and during two levels of exercise: El, 0 or 20 W, E2, 20 or 40 W. Five patients had normal spirometry (group 1), six patients had normal vital capacity but FEV1/VC below 70% (group 2), and 23 patients had VC below 95% of normal and FEV1/VC below 70% (group 3); group 3 was subdivided into group 3a (n= 14) without, and group 3b (n= 9) with a history of right heart failure (RHF).

Right ventricular end‐diastolic (RVEDV) and end‐systolic (RVESV) volumes were computed from stroke volume and right ventricular ejection fraction (RVEF). RVEF at rest was correlated with lung function variables. Changes in RVEF from LR to E2 were normal, i.e. above 0.05, except for in group 3b, where RVEF did not increase with exercise. Relation between RVESV and pressure, and changes in stroke volume with RVEDV from LR to E2 were also abnormal in group 3b. These results show that in patients with chronic lung disease RVEF at rest reflects lung function, whereas its adaptation to exercise is impaired only in patients who have experienced RHF episodes.
Fatigue in the shoulder muscles during static work at two different torque levels
Authors: Gerdle B. , Edström M. , Rahm M.
Published: April 2008

Summary. The present study aimed to investigate whether and when a shift in the mean power frequency (MPF) of the electromyogram (EMG) occurs at low torque levels during a maximum endurance test of three shoulder flexors. Twelve clinically healthy women performed two endurance tests of the shoulder flexors (at 50% MVC‐the high torque level, and at approximately 18% MVC ‐ the low torque level) until maximum exhaustion. Surface EMG were obtained and MPF and signal amplitude (RMS) were computed for the trapezius descendens, the anterior part of the deltoid and the infraspinatus. The subjects also rated the perception of fatigue in the shoulder muscles throughout the two tests using a 10‐graded scale.

A significantly higher degree of perceived fatigue was found at the low rather than at the high torque level. In contrast significantly lower MPF were found at the end of the endurance times in the three muscles at the high torque level when compared to the low torque level. At the low torque level MPF of the trapezius was constant throughout the test. In the deltoid the most prominent decrease occurred during the initial 30–40% of the endurance time at the low torque level.

It is suggested that the MPF shift mainly reflects peripheral fatigue of the type‐2 fibres. The results of the present study question the use of the MPF shift to monitor peripheral fatigue in the fibres active (mainly type‐1) at low torque levels.,
About mechanisms of prostaglandin E1 induced deterioration of pulmonary gas exchange in COPD patients
Authors: Dujisc Ž. , Eterovic D. , Tocilj J. , Kusid Z. , Čapkun V.
Published: April 2008

Summary. Prostaglandin E1 (PGE1) has been reported to attenuate COPD‐related pulmonary hypertension and to slightly lower the arterial oxygen tension (PaO2). In order to infer the involved mechanisms, the effects of intravenous infusion of PGE1 on pulmonary haemodynamics, diffusing lung capacity for CO (DLCO), membrane diffusing capacity (Dm), pulmonary capillary blood volume (Vc), physiological shunt (Qps/Qt), arterial blood gases and other lung functional indices were evaluated in 20 COPD patients with pulmonary hypertension and, excluding right catheterization, in 14 control subjects. The examines were studied at baseline and during infusion of 20–30 ng kg‐1min PGE1 or placebo. In control subjects PGE1 only caused systemic arterial pressure decrease (‐17.8%). In COPD patients, as expected, PGE1 increased cardiac index (16‐2%), but decreased systemic arterial pressure (‐21.2%), pulmonary arterial pressure (‐27.9%), pulmonary vascular resistance (‐45.4%) and PaO2 (‐10.4%), worsening their hypoxaemia. However, the effect of PGE1 on DLCO was an increase (11.9%), due to an increase in Vc (15.2%) and less markedly in Dm (4.9%). Physiological and anatomical shunts were increased with PGE1 (20.2% and 14.8%) and the overall ventilation/perfusion ratio decreased from 0.89 to 0.79. Decrements in PaO2 correlated with increments in Qps/Qt (r= 0.86). In conclusion, in COPD patients studied, PGE1 increased DLCO, which compensated for the deleterious effect of increased cardiac output on alveolar‐capillary gas equilibration. Therefore, worsening of hypoxaemia during PGE1 infusion was related with increased right‐to‐left shunt and deterioration of ventilation‐perfusion relationship.,
Non‐invasive measurement of pulsatile vessel diameter change and elastic properties in human arteries: a methodological study,
Authors: Hansen F. , Bergqvist D. , Mangell P. , Rydén Å. , Sonesson B. , Länne T.
Published: April 2008

Summary. A recently developed ultrasound phase‐locked echo‐tracking system makes it possible to measure non‐invasive pulsatile vessel diameter changes, and, in combination with blood‐pressure measurement, to calculate pressure strain elastic modulus (Ep) and stiffness (β). The reproducibility in measurements of pulsatile diameter changes with this system was evaluated. Also the precision of indirect blood‐pressure measurements, as compared to the simultaneously measured intra‐arterial blood pressure was tested. The resulting reproducibility in pressure strain elastic modulus (Ep) and stiffness (β) was evaluated.

Intra‐observer variabilities in measuring pulsatile diameter changes were 16% for the abdominal aorta, 10% for the common carotid artery, and 15% for the common femoral artery, respectively. Intra‐observer variabilities for Ep and β were 21% for both in the abdominal aorta, 17% for both in the common carotid artery, and 18% for both in the common femoral artery, respectively.

There were only small differences in indirect and direct measurement of systolic blood pressure, whereas indirect blood pressure measurement systematically overestimated the diastolic blood pressure, on average by 20%. The variabilities in indirect blood pressure measurements were 2% for the systolic and 3% for the diastolic blood pressure, respectively.

Inter‐observer variability in the investigation of the common carotid artery was 10% for the pulsatile diameter changes, and 21% and 23% for Ep and β, respectively. Thus, the echo‐tracking system represents a reliable system for estimation of pressure strain elastic modulus and stiffness. However, Ep and β are systematically underestimated by 25–30%, when used in combination with indirect blood pressure measurements.
The effect of hyperosmotic solutions on the hepatic blood flow,
Authors: Winkler K. , Henriksen J. H. , Tygstrupt N.
Published: April 2008

Summary. The present study was undertaken in order to measure the effect of hyperosmotic solutions on portal and hepatic blood flow.

In five anaesthetized pigs without arterial blood supply to the liver, portal blood flow rate was measured (electromagnetic flowmeter) during 5 min lasting intravenous infusions of hyperosmotic galactose (50%, 84–100 ml) and mannitol (25%, 100 ml), with physiological saline (100 ml) as control.

Portal blood flow increased to a peak value of (39% [P= 0–06] galactose and 37%, [P= 0–06], mannitol) soon after stop of the hyperosmotic infusion. For galactose the change ended somewhat earlier than for mannitol. Saline induced a minor increase (15%). Similarly, increments of, on average, 144% of the hepatic blood flow rate was seen in six patients with cirrhosis, following infusion of hyperosmotic galactose, the increase being more pronounced than in the pigs.

The causes for these osmotic effects are not known, but they have to be taken into consideration in studies of the portal and hepatic blood flow.
Differences in glycaemia, hormonal response and energy expenditure after a meal rich in mono‐ and disaccharides compared to a meal rich in polysaccharides in physically fit and sedentary subjects
Authors: Raben A. , Kiens B. , Richter E. A.
Published: April 2008

Summary. Postprandial glycaemia, hormonal response and energy expenditure (EE) were measured after two isocaloric carbohydrate‐rich meals (69 energy‐percent [E%] carbohydrate, 16 E% fat) rich in either mono‐ and disaccharides (47 E%, half of which sucrose) (MD) or polysaccharides (64 E%; P). Both meals were based on natural food items and were tested in a cross‐over design in a group of sedentary (S) and trained (T) healthy, young subjects. Compared with the P meal blood glucose concentrations were significantly decreased and plasma insulin concentration significantly increased after the MD meal. A group difference was observed after the P meal with increased glucose and decreased insulin concentrations for T compared with S. Plasma norepinephrine concentrations were significantly increased after the MD meal compared with the P meal, but for S only. For both groups a significantly increased EE was observed 3 and 5 h after the MD meal compared with the P meal. However, no significant differences between the meals were observed in plasma insulin or catecholamine concentrations 3 and 5 h postprandially, when EE was measured. In conclusion, significant differences were observed in postprandial glucose and hormone responses as well as energy expenditure after two meals based on either mono‐ and disaccharide‐rich or polysaccharide‐rich food items. Physical fitness level influenced the glucose and hormonal responses but not the relative increases in postprandial energy expenditure.
Normal values for QT intervals in ECG during ramp exercise on bicycle
Authors: Wohlfart B. , Pahlm O.
Published: April 2008

Summary. The relation between QT interval and heart rate during ramp exercise tests on a bicycle was investigated in 37 healthy individuals (21 women) without regular medication and with a normal thallium‐201 exercise scintigram (mean age 52–9 ± 8–3, range 38–68). The test started at 20 W and the load increased by 10 W min‐1. A 12‐lead ECG was recorded twice every min and mean complexes (during a 15 s period) were calculated by computer. At rest the QT interval (in s) corrected for heart rate (QTC) for women and men was 0–408 ± 0–004 and 0–399 ± 0–005, respectively, P > 0–05). During exercise there was no difference in QT interval between women and men or between younger (<50 years) and older (> 50 years) individuals. A straight line was used to describe the relation between QT interval and heart rate (beats min‐1; QT = 0–459–12–3xlO‐4*HR). A 95% prediction interval around the regression line was determined using a non‐parametric statistical method. When QTC was calculated using Bazett's formula with a cut‐off value of QTc= 0–46, 19 individuals (11 women) had a prolonged QT interval during exercise. It is concluded that the relation between QT interval and heart rate can during exercise be described by a straight line for normal individuals. It is not valid to use Bazett's formula for correction of QT intervals during ramp exercise tests.
Subcutaneous noradrenaline concentration increase in normal subjects during cold exposure evaluated by microdialysis
Authors: Grønlund B. , Grønlund L. , Christensen N. J.
Published: April 2008

Summary. Changes in local noradrenaline level in subcutaneous tissue were measured in four healthy males (23–33 years) during cold stimulation using a microdialysis technique.

The subcutaneous dialysate noradrenaline concentration increased during cold exposure by a factor of 3–5 (P<0–003). A correction factor due to plasma overflow of noradrenaline to subcutaneous tissue was calculated from noradrenaline infusion studies. This correction had a minimal effect on the observed increase in dialysate noradrenaline concentration and the level of significance was only slightly altered after correction for plasma overflow.

The microdialysis technique in combination with a sensitive radioenzymatic noradrenaline assay may be useful to assess changes in local subcutaneous noradrenaline level in man during physiological stimulation.
Growth hormone suppression and glutamine flux associated with cardiac surgery
Authors: Powell H. , Castell L. M. , Parry‐Billings M. , Desborough J. P. , Hall G. M. , Newsholme E. A.
Published: April 2008

Summary. Pharmacological doses of growth hormone (GH) in humans and rats increase plasma and muscle glutamine values. As major surgery results in a physiological rise in serum GH concentration, we investigated whether this physiological increase in GH altered glutamine metabolism. Eighteen patients undergoing coronary artery bypass graft (CABG) surgery were randomly assigned to receive somatostatin, 100 μg subcu‐taneously at induction of anaesthesia and 8 hourly for 48 h, or placebo. Somatostatin effectively blocked the physiological surge of GH following injury but did not affect plasma or muscle glutamine concentrations, which fell significantly in both groups. Plasma glutamine decreased by 31% (P<0–01) and 28% (P<0–01) in the control and somatostatin groups respectively. Muscle glutamine was reduced 45% (P<0–001) in the control group and 50% (P<0–001) in the somatostatin group. There was no difference in muscle or circulating glutamate, alanine or branched chain amino acid concentrations or in metabolite values between the somatostatin‐treated patients and the control group. There was no relationship between the GH response to surgery and glutamine metabolism following major surgery.
Influence of shear on skin oxygen tension
Authors: Goossens R. H. M. , Zegers R. , van Dijke G. A. Hoek , Snijders C. J.
Published: April 2008

Summary. Since the early studies on decubitus many authors expect significant influence of shear on decubitus risk. In the study described here skin oxygen tension at the sacrum was measured with combined pressure and shear stress on a young healthy population (mean age 25‐5 years, SD 3–4 years).

Cut‐off pressure is defined as the level of external pressure exerted on the skin at which the skin oxygen tension is 1–3 kPa. At this level ischaemia of the skin can be expected (Bar, 1988). A mean cut‐off pressure of 11‐6 kPa was found when no shear stress was applied vs. a significantly lower mean cut‐off pressure of 8‐7 kPa with a shear stress of 3‐1 kPa.

No significant relationship was found between cut‐off pressure and systolic blood pressure, diastolic blood pressure, skin thickness at the sacrum, percentage of fat and skin oxygen tension in the unloaded situation.,
Stretch‐induced myogenic responses of airways after histamine and carbachol
Authors: Thulesius O. , Mustafa S.
Published: April 2008

Summary. The purpose of the study described here was to determine the possible role of a myogenic response of bronchial smooth muscle in deep inspiration (Dl)‐induced bronchoconstriction.

Model experiments were performed on sheep tracheal strips. The effect of sudden stepwise elongation on isometric tension of tracheal muscle was studied in the absence and presence of the bronchoconstrictors carbachol (10‐8 M) and histamine (10‐4 M). In control strips tension increased rapidly with stretch and was followed by stress relaxation which corresponds to creep or bronchial dilatation. In histamine‐and carbachol‐treated strips a reactive contraction with a rhythmic pattern interrupted the process of stress relaxation. These responses appeared after only 20% elongation and were characteristic of a myogenic contraction which in the in vivo situation would correspond to a bronchoconstriction. These findings are interpreted as a functional transformation of multiple‐to single‐unit smooth muscle due to the influence of carbachol and histamine.

This suggests that stretching (DI) of bronchial smooth muscle in the presence of carbachol and histamine induces a protracted myogenic contraction, which may explain bronchoconstriction after DI in severe asthma.,
Pronounced bronchial hyper‐responsiveness and asthma severity
Authors: Plaschke P. , Bake B.
Published: April 2008

Summary. Fifty‐six asthmatics from an asthma ward or from an asthma out‐patient clinic were challenged with two low concentrations (0–03 and 0–012 mg) of metacholine chloride in order to assess the relationship between pronounced hyper‐responsiveness and asthma severity in a clinical setting. Only inhaled bronchodilators were stopped before challenge. Asthma severity was assessed retrospectively and prospectively on the basis of treatment, number of days in hospital, intensive care, number of emergency visits and days on sick‐leave. The results show that pronounced hyper‐responsiveness (n= 28) is not associated with asthma severity. It is concluded that a single simplified test of pronounced bronchial hyper‐responsiveness, performed without taking into consideration the actual state of the disease and without stopping all medication, is of no help in identifying the patients with the clinically most severe asthma and worst prognosis.,
Cerebral perfusion during human liver transplantation
Authors: Pott F. , Larsen F. S. , Ejlersen E. , Linkis P. , Jørgensen L. G. , Secher N. H.
Published: April 2008

Summary. During transplantation of the liver cerebral perfusion was monitored by transcranial Doppler determined middle cerebral artery mean flow velocity (Vmean) and pulsatility index (PI) in six fulminant hepatic failure patients and 11 patients with chronic liver disease. In both groups of patients Vmean, PI and central haemodynamic variables were recorded during (1) the last preanhepatic hour; (2) the anhepatic phase; (3) the first 15 min of reperfusion; and (4) for the following 45 min of reperfusion. No significant differences were detected between the two groups of patients with respect to changes of variables with time. The Vmean (40±13 cm s‐1 [mean±SD]), thoracic electrical impedance (TI) (30±7 Ohm), heart rate (97±19 beats min‐1), mean arterial pressure (84±9 mmHg) and arterial carbon dioxide tension (PaCO2, 4.5±0.4 kPa) remained stable in the anhepatic phase, while cardiac output (CO, 7.6±2.7 to 5.4±1.41 min‐1), stroke volume (SV, 79±26 to 56±15 ml) and PI (1.2±0.3 to 0.9±0.2) decreased (P<0.05). During reperfusion, CO (9.9±4.01 min‐1), SV (105±40 ml), PaCO2 (5.5±0.6 kPa), Vmean (57±17 cm s‐1) and PI (1.2±0.2) became elevated. Taken together, during the anhepatic phase of the liver transplantation a maintained central blood volume as indicated by the constant TI served for a stable blood pressure and in turn cerebral perfusion, whereas revascularization of the graft increased cerebral perfusion concomitant with an elevated carbon dioxide tension.
Cardiovascular response in patients with and without myocardial ischaemia during dobutamine echocardiography stress test for coronary artery disease
Authors: Aakhus S. , Bjørnstad K. , Hatle L.
Published: April 2008

Summary. Dobutamine is widely used in cardiac stress testing for coronary artery disease and myocardial viability. To assess the systemic cardiovascular response during dobutamine echocardiography stress testing, we investigated nine patients without myocardial ischaemia (group 1, aged 48 to 72 years) and nine patients with myocardial ischaemia during the test (group 2, aged 53 to 73 years), by use of Doppler/echocardiography and subclavian artery pulse trace calibrated with brachial artery pressures. Peripheral resistance, total arterial compliance, and aortic characteristic impedance were estimated using a 3‐element windkessel model of the systemic circulation. During infusion of dobutamine up to 40 μg kg‐1 min‐1, arterial pressure was maintained near baseline levels, whereas heart rate and cardiac index increased, more so in group 1 (mean: 89 and 79%) than in group 2 (58 and 52%; P<0.05 vs. group 1). Peripheral resistance was decreased by ≥32% at peak stress, whereas characteristic impedance was maintained at or above baseline in both groups, and total arterial compliance was not significantly altered. The cardiovascular response in group 2 was not influenced by the wall motion abnormalities. Thus, in these patients the inotropic, chronotropic, and vasodilatory effects of dobutamine balanced the ischaemic impairment of left ventricular function during the stress test.
Lung function in Estonian children: effect of sitting height
Authors: Kivastik J. , Kingisepp P.‐H.
Published: April 2008

Summary. The present analysis formed part of the population study of Estonian schoolchildren and was undertaken in order to examine the relationships between lung function variables, standing and sitting height. We measured forced vital capacity (FVC), forced expiratory volume in 1 s (FEVj), peak expiratory flow and forced expiratory flows when 50 and 75% of FVC had been exhaled, and anthropometric indices in 645 healthy schoolchildren, aged 6–18 years. The growth spurt in standing and sitting height occurred between the ages of 11 and 13 years in girls, and 13 and 15 years in boys. Growth spurts of lung parameters occurred during the same periods. FVC and FEVj showed close correlations (r=0.89‐0.94) with all anthropometric parameters and age, whereas correlation coefficients for the flows were less close (r=0.65‐0.88). In boys, correlations between sitting height and lung function variables were greater than those with standing height. Using stepwise regression analysis, in boys sitting height was selected in all lung function parameters, and in girls sitting height was never selected. We conclude that there is a very close correlation between sitting height and lung function variables. The use of sitting height in parallel with standing height in predicted values for Estonian schoolchildren would make the values more exact.
CAVIAR: a tool to improve serial analysis of the 12‐lead electrocardiogram
Authors: Berg J. , Fayn J. , Edenbrandt L. , Lundh B. , Malmström P. , Rubel P.
Published: April 2008

Summary. An important part of an electrocardiogram (ECG) interpretation is the comparison between the present ECG and earlier recordings. The purpose of the present study was to evaluate a combination of two computer‐based methods, synthesized vectorcardiogram (VCG) and CAVIAR, in this comparison. The methods were applied to a group of 38 normal subjects and to a group of 36 patients treated with anthracyclines. A fraction of these patients are likely to develop cardiac injury during or after the treatment, since anthracyclines are known to cause heart failure and cardiomyopathy. Two ECGs were recorded on each patient, one before and one after the treatment. On each normal subject, two ECGs were recorded with an interval of 8–9 years. A synthesized VCG was calculated from each ECG and the two synthesized VCGs from each subject were analysed with the CAVIAR method. The CAVIAR analysis is a quantitative method and normal limits for four measurements were established using the normal group. Values above these limits were more frequent in the patient group than in the normal group. The conventional ECGs were also analysed visually by an experienced ECG interpreter without knowledge of the result of the CAVIAR analysis. No significant serial changes were found in 10 of the patients with high CAVIAR values. Changes in the ECGs were found in two patients with normal CAVIAR values. In summary, synthesized VCG and CAVIAR could be used to highlight small serial changes that are difficult to find in a visual analysis of ECGs.
Ventilation‐perfusion inequality in nocturnal hypoxaemia due to chronic obstructive lung disease (COLD)
Authors: Sandek K. , Andersson T. , Bratel T. , Lagerstrand L.
Published: April 2008

Summary. Nocturnal hypoxaemia is often noted in COLD patients with a daytime PaO2 above 8.0 kPa. It has been assumed that ventilation‐perfusion inequality contributes to nocturnal hypoxaemia. 10 patients with advanced COLD [median FEV1 0.73 (range 0.50‐1.32)1], but without daytime hypoxaemia [median PaO2 8.35 (range 8.0–12.2) kPa] were investigated with regard to possible nocturnal hypoxaemia using polysomnography. Daytime lung function was assessed by spirometry and carbon monoxide diffusion capacity (DLCO). Daytime ventilation‐perfusion (VA/Q) relationships were measured by the multiple inert gas elimination technique.

Dispersion of perfusion and ventilation distributions was increased [log SDQ 1.01 (range 0.80‐1.35) and log SDV 0.91 (range 0.69‐1.86) resp.]. Around 8% of the ventilation was directed towards high VA/Q areas (10< VA/Q<100). All subjects reached all sleep stages, and all but one had a nadir nocturnal oxygen saturation (SaO2) of below 90%. Their median lowest nocturnal SaO2 was 84.0 (range 70.93)% and their mean oxygen saturation in the course of desaturation episodes (Mmin SaO2) was 86.4 (range 83.6–91.5)%. An increased mean VA/Q ratio of ventilation distribution was associated with a reduced DLco Increased nocturnal episodes of wakefulness and of stage I sleep correlated with increased dead space ventilation and dispersion of the ventilation distribution. Patients with deep nocturnal desaturations had a low mean VA/Q ratio of the perfusion distribution (Q mean) (r=0.87, P<0.01) and increased perfusion of inferior VA/Q areas (0.1 VA/Q<0.3). Low Mmin SaO2 was associated with low morning PaO2 and a low Q mean.

COLD patients with solely nocturnal hypoxaemia have a high degree of pulmonary hyperinflation and emphysema. Increased sleep disruption is associated with more severe small airway disease. Increased perfusion of sparsely ventilated areas is associated with more pronounced nocturnal desaturations.