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Biomedical subjects

P Olofsson

Publications and source records attributed to P Olofsson.

At least 55 records · Page 3Linked to original sources
PubMed1995

Effect of a prostaglandin E1 analogue (gemeprost) on uterine and luteal circulation in normal first trimester pregnancies. A Doppler velocimetry study.

OBJECTIVE: To evaluate the effects of gemeprost on utero-placental and luteal circulation and on the embryo/fetus in normal first trimester pregnancies. STUDY DESIGN: Sixty-seven women with a normal first trimester pregnancy requesting termination of pregnancy for psychosocial reasons were randomly allocated to pre-operative treatment with vaginal suppositories containing placebo or gemeprost. The women underwent transvaginal color and spectral Doppler ultrasound examination before the application of the suppository, 4 h after the application of the suppository but before the abortion, and on the seventh post-operative day. Blood flow velocities in the uterine and subchorionic arteries, the intrachorionic area and arteries in the wall of the corpus luteum and the embryonic/fetal heart rate were measured. RESULTS: The median value for pulsatility index (PI) in the dominant uterine artery was 2.4 before treatment with gemeprost and 8.5 4 h after treatment (P = 0.0006); the corresponding values for time-averaged maximum velocity (TAMXV) being 27 cm/s and 10 cm/s (P = 0.0006). Four (14%) of 28 embryos/fetuses in the gemeprost group were dead 4 h after treatment with gemeprost and the median heart rate of those still alive was significantly lower than before treatment (130 vs. 163 bpm; P = 0.003). In the placebo group, the results for the uterine arteries and the embryonic/fetal heart rate did not differ significantly between the first and second ultrasound examinations. The median values for PI and TAMXV in the arteries of the corpus luteum wall at the first ultrasound examination were 0.71 and 18 cm/s, respectively, in the placebo group and 0.71 and 20 cm/s, respectively, in the gemeprost group. These values remained almost unchanged at the second and third ultrasound examinations in both groups. CONCLUSION: Gemeprost has profound effects on utero-placental circulation in the first trimester and can induce embryonic/fetal bradycardia and sometimes embryonic/fetal demise. It has no unequivocal effect on luteal circulation.

Abortion, Induced↗
PubMed1995

Histopathological characteristics of explanted human prosthetic arterial grafts: implications for the prevention and management of graft infection.

OBJECTIVE: to study the histopathological characteristics of prosthetic vascular graft infection. DESIGN: prospective clinical study over 2 years. SETTING: University Hospital. MATERIALS: 36 infected and 29 uninfected (control) chronically implanted vascular prostheses (half aortic) were removed and 352 sections prepared. CHIEF OUTCOME MEASURES: light microscopy (multiple stains), scanning electron microscopy (SEM), and multiple culture techniques to identify characteristics of healing, infection, and microorganisms. MAIN RESULTS: Acute inflammation (AI) (neurophils, granulocytes and necrosis) were seen in 75% of infected grafts, were most prominent in the perigraft tissue and rarely seen on the luminal surface. These were usually well localised, leaving the remainder of a graft well incorporated with no signs of infection. In 25% of clinically infected, culture-positive grafts there was no significant acute inflammation. Chronic inflammation (CI) (macrophages, lymphocytes, monocytes, giant cells) was seen in 70% of both control and infected grafts. In 50% of both groups a significant lymphocytic population was composed exclusively of T-lymphocytes suggesting a true host vs graft response. Unincorporated chronically implanted grafts (> 1 yr) were seen with equal frequency in the two groups although more diffusely unincorporated grafts were infected. Microorganisms were cultured from 23 infected grafts (64%) and were, at microscopy, mostly found outside the graft and nerves on the luminal side. CONCLUSIONS: This data cast doubt on criteria commonly used to distinguish graft infections and host vs. graft reactions from normal graft healing. Acute and chronic inflammation are not predictive of infection.

Acute Disease↗
PubMed1995

Changes in postocclusive reactive hyperaemic values as measured with laser Doppler fluxmetry after infrainguinal arterial reconstructions.

OBJECTIVES: The aim of the present study was to evaluate microcirculartory changes of the postocclusive reactive hyperaemia test measured with Laser Doppler fluxmetry to detect results of arterial reconstructions. DESIGN: Prospective open study. SETTING: Vascular laboratory of a University Hospital. MATERIAL: Sixty patients with peripheral arterial occlusive disease who underwent infrainguinal reconstruction were examined the day before and 1-2 days after surgery. CHIEF OUTCOME MEASURES: The values were obtained during postocclusive reactive hyperaemia induced by release of a 3 min arterial occlusion with a cuff at ankle level with the laser Doppler probe placed dorsally on the first toe. The alterations after surgery in these hyperaemia parameters were compared to changes in ankle/brachial index and clinical improvement at 30 days postoperatively. MAIN RESULTS: Patients improved by surgery according to ankle/brachial index had significantly reduced time to peak (p < 0.001) and significantly increased resting flux value (p < 0.05) and peak flux value (p < 0.05). There was a significant correlation between the change after surgery in time to peak flux and increment of ankle/brachial index (r = 0.63, p < 0.001). CONCLUSIONS: Changes in reactive hyperaemia values as measured with laser Doppler fluxmetry, especially the time to peak flux, seem to detect circulatory changes caused by arterial reconstructions.

Aged↗
PubMed1995

The "ad hoc" estimation of outflow does not predict patency of infrainguinal reconstructions.

OBJECTIVES: This prospective study was performed to evaluate the clinical implication of the adhoc estimation (also called SVS score) of outflow on patency of infrainguinal in situ femoropopliteal or -distal bypasses. METHODS: The bypasses were followed with Duplex scanning at 1, 3, 6, and 12 months after surgery. Fifty-three bypasses were recruited for the study, 20 of which were performed in 17 diabetics. In 47% the adhoc scoring was < or = 4.5 and in 53% it was between 5 and 10 (1 corresponds to an excellent outflow and 10 to a blind segment). RESULTS: Within the first 30 days eight occlusions occurred, all of which were surgically corrected. The adhoc score for these bypasses was 4.2 vs. 4.9 (NS) for those who did not occlude. During follow-up, revisions were performed in 21 cases (40%) with 30 interventions. At the end of 1 year, 68% of the bypasses were patent (80% among diabetics and 64% among non-diabetics, NS). Patency at 1 year was not influenced by the adhoc classification. CONCLUSION: The estimation of outflow from angiography seems to be of no value in predicting graft patency in infrainguinal grafting.

Adult↗
PubMed1995

Increasing mean skin temperature linearly reduces the core-temperature thresholds for vasoconstriction and shivering in humans.

BACKGROUND: The contribution of mean skin temperature to the thresholds for sweating and active precapillary vasodilation has been evaluated in numerous human studies. In contrast, the contribution of skin temperature to the control of cold responses such as arteriovenous shunt vasoconstriction and shivering is less well established. Accordingly, the authors tested the hypothesis that mean skin and core temperatures are linearly related at the vasoconstriction and shivering thresholds in men. Because the relation between skin and core temperatures might vary by gender, the cutaneous contribution to thermoregulatory control also was determined in women. METHODS: In the first portion of the study, six men participated on 5 randomly ordered days, during which mean skin temperatures were maintained near 31, 34, 35, 36, and 37 degrees C. Core hypothermia was induced by central venous infusion of cold lactated Ringer's solution sufficient to induce peripheral vasoconstriction and shivering. The core-temperature thresholds were then plotted against skin temperature and a linear regression fit to the values. The relative skin and core contributions to the control of each response were calculated from the slopes of the regression equations. In the second portion of the study, six women participated on three randomly ordered days, during which mean skin temperatures were maintained near 31, 35, and 37 degrees C. At each designated skin temperature, core hypothermia sufficient to induce peripheral vasoconstriction and/or shivering was again induced by central venous infusion of cold lactated Ringer's solution. The cutaneous contributions to control of each response were then calculated from the skin- and core-temperature pairs at the vasoconstriction and shivering thresholds. RESULTS: There was a linear relation between mean skin and core temperatures at the response thresholds in the men: r = 0.90 +/- 0.06 for vasoconstriction and r = 0.94 +/- 0.07 for shivering. Skin temperature contributed 20 +/- 6% to vasoconstriction and 19 +/- 8% to shivering. Skin temperature in the women contributed to 18 +/- 4% to vasoconstriction and 18 +/- 7% to shivering, values not differing significantly from those in men. There was no apparent correlation between the cutaneous contributions to vasoconstriction and shivering in individual volunteers. CONCLUSIONS: These data indicate that skin and core temperatures contribute linearly to the control of vasoconstriction and shivering in men and that the cutaneous contributions average approximately 20% in both men and women. The same coefficients thus can be used to compensate for experimental skin temperature manipulations in men and women. However, the cutaneous contributions to each response vary among volunteers; furthermore, the contributions to the two responses vary within volunteers.

Adult↗
PubMed1995

Effects of head-down tilt on atrial natriuretic peptide and the renin system in pregnancy.

We studied the effects of head-down tilt to 10 degrees for 30 minutes on plasma atrial natriuretic peptide and the renin-aldosterone system in 8 preeclamptic pregnant women, 8 healthy pregnant women, and 11 nonpregnant women of fertile age. Mean arterial blood pressure did not change in the pregnant groups but increased significantly in the nonpregnant control subjects. Heart rate decreased significantly in preeclamptic women but remained unchanged in both control groups. Baseline atrial natriuretic peptide concentration was significantly higher in both preeclamptic (66 +/- 4 pmol/L) and pregnant (54 +/- 6 pmol/L) control subjects compared with nonpregnant subjects (40 +/- 2 pmol/L), but the difference between the pregnant groups was not significant. Head-down tilting induced a significant increase in atrial natriuretic peptide only in healthy pregnant women. Baseline plasma renin activity and aldosterone concentrations were significantly higher in pregnant control subjects compared with both the preeclamptic and nonpregnant groups. The differences between the preeclamptic and nonpregnant control groups were nonsignificant. After head-down tilting, plasma renin activity decreased significantly only in nonpregnant control subjects, whereas aldosterone decreased significantly in preeclamptic and nonpregnant control subjects. In preeclampsia, atrial natriuretic peptide release followed blood pressure and not changes in cardiac output. When all 27 women were studied, a correlation between atrial natriuretic peptide and mean arterial pressure was found in the left lateral supine position. The results suggest that pregnant women developing preeclampsia lose their usual hemodynamic control and show reactions resembling the nonpregnant state when subjected to head-down tilt.

Adult↗
PubMed1995

Lack of association between Doppler velocimetry and synthesis of prostacyclin and thromboxane in umbilical cord vessels from growth retarded fetuses.

BACKGROUND: The aim of this study was to investigate the possible association between Doppler velocimetry and synthesis of prostacyclin (PGI2) and thromboxane A2 (TxA2) in umbilical cord vessels. The hypothesis was that an altered balance between PGI2 and TxA2 production is associated with a change of artery flow resistance. METHODS: 17 cases with a suspicion of intrauterine growth retardation and 21 normal pregnancies were studied. The umbilical artery pulsatility index (PI) and venous mean velocity were recorded in vivo by Doppler velocimetry. Cord vessel prostanoid synthesis was determined in vitro. The Mann-Whitney U test and simple linear regression were used for statistical analyses. RESULTS: The umbilical vessel synthesis of both PGI2 and TxA2 was in general lower in small-for-gestational age (SGA) cases (n = 10) compared to appropriate-for-gestational age (AGA) (n = 28). In the vein, the PGI2/TxA2 ratio was significantly lower in SGA cases. No certain correlations were found between umbilical artery PI and venous velocity, respectively, and PGI2 or TxA2, or their ratio. CONCLUSION: The prostanoid synthesis was in general lower in SGA cases, resulting in a significantly lower PGI2/TxA2 ratio in the umbilical vein. This indicates that fetal growth retardation might be associated with a disturbed endothelial function in this vessel. The synthesis of PGI2 and TxA2 in the juxtaplacental umbilical cord vessels was not correlated to the umbilical artery PI or venous flow velocity. It is possible that an altered release of prostanoids in the placental vasculature and tissue accounts for the rise of umbilical artery flow resistance instead.

6-Ketoprostaglandin F1 alpha↗
PubMed1995

A comparison between conventional and 24-hour automatic blood pressure monitoring in hypertensive pregnancy.

OBJECTIVE: To map the conformity between 24-hour and conventional blood pressure (BP) monitoring (24BPM, CBPM) in pregnancy. STUDY DESIGN: Prospective comparative. MATERIAL AND METHODS: A standardized single BP measurement and parallel 24BPM and CBPM were carried out in 99 women (125 recordings) hospitalized for hypertension. RESULTS: Except for BP oscillation amplitude, corresponding variables correlated significantly between the methods. The mean systolic BP (SBP) was significantly higher with 24BPM compared with both CBPM (3.1 mmHg) and with the single BP measurement (4.6 mmHg). The mean diastolic BP (DBP) was significantly lower with 24BPM compared with CBPM (2.4 mmHg) and with the single measurement (2.7 mmHg). If a cut-off at 140/90 mmHg had been used for the diagnosis of hypertension and with 24BPM as the golden standard, a false positive/negative diagnosis would have resulted in 35%/20% of cases with the single BP measurement, and in 24%/17% with CBPM. CONCLUSIONS: 24BPM and CBPM gave significantly correlated but different values of the BP. The differences were small in terms of absolute mm Hg values, but resulted in a high rate of false positive and false negative diagnoses of hypertension. 24BPM cannot substitute the traditional methods for BP monitoring in pregnancy unless a new definition of hypertension is established.

Adolescent↗
PubMed1995

Characteristics of a reversed circadian blood pressure rhythm in pregnant women with hypertension.

The objective of the study was to describe the 24h blood pressure (BP) pattern in pregnant women with a reversed circadian BP rhythm. The 24h BP monitorings (24BPM) were performed in 73 pregnant women hospitalised for hypertension. Daytime (6.00 am to 10.00 pm) and night-time (10.00 pm to 6.00 am) BP variables were calculated. A reversed circadian BP rhythm was defined as a day/night mean BP ratio < 1.0. Fourteen women had a reversed circadian BP rhythm. Their diurnal mean BP was equal to women with a normal rhythm, but their nocturnal mean BP was significantly higher and their BP oscillation amplitudes tended to be lower. The day/night mean SBP and DBP ratios correlated significantly, with the DBP ratios slightly higher than corresponding SBP ratios. At repeated 24BPM (n = 14), the day/night ratio did not change but a reversed rhythm occurred during anti-hypertensive medication in one case, and a reversed rhythm switched spontaneously to normal in one case. The diurnal BP pattern did not differ between women with a reversed and a normal circadian BP rhythm. Women with a reversed rhythm had a higher nocturnal BP, but this was part of the definition. The BP variations were generally smaller in the group with a reversed rhythm, although the variations were still large. The definition with a day/night ratio cut-off at 1.0 was rather a convenient mathematical choice than a biologically-determined limit. The day/night BP ratio remained unchanged at repeated measurements, but a reversed rhythm was not a constant phenomenon in occasional cases. Women with a reversed circadian BP rhythm were therefore not a well-defined group and, with exception for a tendency to smaller BP fluctuations, no specific behavioural BP pattern could be described. Until the normal circadian BP rhythm in normal pregnancy has been described, there is no possibility to identify women with an abnormal circadian BP rhythm. Ideally, any definition of an abnormal rhythm should be related to the clinical relevance.

Adolescent↗
PubMed1995

PAS-Port: a new implantable vascular access device for arm placement: experiences from the first two years.

OBJECTIVE: To evaluate the performance of a new subcutaneous infusion port for placement in the arm. DESIGN: Retrospective study. SETTING: Karolinska Hospital, Stockholm, Sweden. SUBJECTS: 85 of 90 consecutive patients referred for implantation of a subcutaneous infusion port. Five records were missing. Implantation was successful in 81 cases (95%). INTERVENTIONS: Implantation of a PAS-Port (Kabi Pharmacia Deltec) subcutaneously on the forearm. Vascular access was obtained by cut-down. MAIN OUTCOME MEASURES: Success rate, complications and reliability in routine use. RESULTS: After a follow-up time of 1-24 months (median 5), 42 ports were still in use, 21 patients had died with functioning ports, two ports had been removed at the end of treatment, 11 had been removed because of complications and because they malfunctioned; and 3 patients were lost to follow-up. The overall infection rate was 0.08/100 catheter days. CONCLUSIONS: PAS-Port is a safe alternative to chest-placed port systems where there is a need for long term vascular access in adult patients.

Adolescent↗
PubMed1994

Infusion methods for determination of peripheral resistance: influence of infused medium and back pressure.

It has been suggested that peripheral vascular resistance (PR), measured intraoperatively, can predict the outcome of infrainguinal reconstructions. There is, however, a great deal of variability in design and predictive value with this method, and it is prone to technical difficulties and possible errors. The present study evaluated the influence of the choice of infusion medium and the back pressure on PR as measured by the infusion technique. In a porcine model of experimentally induced stenosis, standard PR (calculated by the pressure difference across the stenosis and the Doppler volume flow) was compared with PR based on infusions of blood or saline solution. With blood as the infusion medium there was a significant correlation between the PR and the standard values (r = 0.795, p = 0.0005), whereas there was no correlation when saline solution was infused (r = 0.067, p = 0.345). Subtracting the back pressure resulted in a slight improvement in the correlations between standard PR and PR measured after infusion of blood but not saline solution. In summary, blood should be used as an infusion medium in methods of PR determination, but the influence of back pressure remains uncertain.

Animals↗
PubMed1994

Correlation between peripheral vascular resistance and time to peak flow during reactive hyperaemia.

Earlier studies have proposed that the time to reach peak hyperaemic flux recorded with laser Doppler (tp) is a simple and accurate method of evaluating ischaemic limbs and possibly a method of estimating the peripheral vascular resistance (PR). The aim of this study was to investigate the relationship between the tp and changes in limb vascular resistance caused by arterial stenosis. Forty postocclusive hyperaemia tests with arterial stenoses of different pressure gradients were performed in four pigs. A laser Doppler fluxmeter was used to record postocclusive hyperaemia in the skin of one hind limb. A specially designed tourniquet was used for the arterial occlusion. Proximal and distal to the occlusion level a snare was used to form different grades of stenosis. The PR (mmHg.ml-1.min-1) was either estimated by infusion of a known blood volume into the tested limb over a given time period with simultaneous measurement of pressure or calculated on the basis of measurements of limb blood flow and blood pressure gradients. The tp was closely related to total limb vascular resistance assessed by the blood infusion method (r = 0.83, p < 0.0003) and to the resistance calculated from volume blood flow and intraarterial pressures (r = 0.86, p < 0.0001). This study suggests that the tp accurately reflects limb vascular resistance in an experimental model. Thus tp may be used as a quantitative indicator of overall blood flow impairment, and should be evaluated in patients with lower-limb atherosclerosis.

Animals↗
PubMed1994

Renal function and urinary urokinase in hypertensive and diabetic pregnancies.

Urokinase (u-PA) dissolves and removes fibrin deposits in the renal secretory pathways in various renal diseases. During pregnancy nephropathy creates a problem in preeclampsia and diabetes, but the underlying mechanism of glomerular damage is different. Preeclamptic nephropathy is characterized as 'glomerular endotheliosis' with hypertrophy of the intracapillary cells, and diabetic nephropathy as 'glomerulosclerosis' with hyaline deposits. The role of fibrin deposition for the etiology of renal damage in preeclampsia is controversial. Changes of the urinary secretion of u-PA may reflect the type of glomerular damage. Our hypotheses were that renal insufficiency is associated with a low u-PA activity in both conditions, and that severe disease is parallel to declining concentrations of u-PA. We compared the glomerular filtration rate, S-Creatinine and S-Urate with urinary u-PA excretion in 24 hypertensive and 20 diabetic pregnant women. In diabetic patients, a low u-PA concentrations was associated with an impaired renal function. In hypertensive pregnancy, the u-PA excretion did not reflect the severity of the hypertensive disease or renal function. No association was found between u-PA excretion and renal function post partum in any group. We conclude that renal urokinase activity plays a role for renal function in diabetic but not in hypertensive pregnancy.

Female↗
PubMed1994

Limb loss in association with vascular surgery--a five-year series of major lower-limb amputation.

OBJECTIVE: To evaluate the type, timing and number of vascular reconstructions that preceded amputation; to compare the characteristics of amputees who had had reconstructions with those of amputees who had not, and to compare the results of amputation. DESIGN: Retrospective study of case notes. SETTING: University hospital, Sweden. SUBJECTS: All 219 patients who underwent amputation between 1987 and 1992. MAIN OUTCOME MEASURES: Incidence of amputations; presenting features, and type and results of vascular reconstructions. RESULTS: The number of amputations decreased after 1988, and that of vascular reconstructions increased. 56 of the 99 who had amputations after reconstruction (57%) had had their last procedure within a month. This group had had a mean of three operations, had worse run-off as assessed by angiography, and 2 of them (5%) had amputations after failed suprainguinal reconstruction for claudication alone. 68 of the total (31%) had amputations without first being assessed by a vascular surgeon. 52 (24%) required reamputation. CONCLUSION: Better objective methods are needed for the assessment of patients before primary as well as secondary vascular reconstructions. All patients should be seen by a vascular surgeon before amputation is recommended.

Adult↗
PubMed1993

A high uterine artery pulsatility index reflects a defective development of placental bed spiral arteries in pregnancies complicated by hypertension and fetal growth retardation.

INTRODUCTION: The development of PIH is associated with a defective trophoblast invasion and conversion of spiral arteries into low-resistance uteroplacental arteries. Hypertension may then be a compensatory response to a defective uteroplacental perfusion. Similar mechanisms may operate in IUGR. AIM: To compare uterine artery Doppler blood flow measurements with placental bed histology. The hypothesis was that placental bed vessel pathology plays a role for a raised flow resistance. MATERIALS AND METHODS: After blood flow measurements, a placental bed biopsy was taken at CS in 26 complicated (study group) and 29 uncomplicated pregnancies (control group). RESULTS: The uterine artery PI was significantly more often abnormally high in the study group compared with the control group, and also in hypertensive pregnancies compared with normotensive IUGR pregnancies. Physiological vessel changes were found in all controls but were absent in 76% of study cases. Physiological changes were significantly more often absent in SGA than in AGA newborns. Absence of physiological changes were significantly more often found in cases with an abnormally high PI. DISCUSSION: The results link together circulatory and structural pathophysiological changes of the uteroplacental unit. A defective physiological conversion of the spiral arteries was associated with an increased uterine flow resistance. CONCLUSION: This study gave further support for the existence of a triad of defective placental bed vessel maturation, increased uteroplacental flow resistance, and hypertension.

Adolescent↗
PubMed1993

Level of arterial obstruction in patients with peripheral arterial occlusive disease (PAOD) determined by laser Doppler fluxmetry.

AIM: To evaluate the laser Doppler fluxmeter as a non-invasive screening method to determine the level of peripheral arterial occlusive disease (PAOD) in the lower limb. DESIGN: Open study of the veno-arterial reflex (VAR) during a shift in body position using a laser Doppler fluxmeter at five probe positions distal to the knee, compared with the occlusion level determined by arteriography and segmental plethysmography. MATERIALS: 50 legs comprising 10 normal controls, 20 legs with suprainguinal obstructions (10 claudication and 10 critical ischaemia) and 20 legs with infrainguinal obstructions (10 claudication and 10 critical ischaemia). RESULTS: Controls had normal VAR (mean flux reductions of 38% during dependency) at all probe positions. Legs with infrainguinal disease had normal reflexes proximally but significantly disturbed reflexes distally, whereas suprainguinal disease showed alterations at all sites. Claudicants had diminished flux reduction (mean 12%) whilst those with critical ischaemia increased the flux (mean 32%). CONCLUSION: This simple, non-invasive technique may be of use in determining the level of obstruction in PAOD.

Aged↗