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Biomedical subjects

P Ohlin

Publications and source records attributed to P Ohlin.

At least 19 recordsLinked to original sources
PubMed2001

Factors influencing 133-xenon washout in a nose-sinus model.

The 133-xenon washout technique is a non-invasive method for the evaluation of ventilation of the paranasal sinuses. The half-time of 133-xenon washout (T(1/2)) is considered to reflect sinus ostial function and sinus ventilation. However, it is not known how morphological and physiological factors affect the washout from the paranasal sinuses. The aim of the present study was to evaluate how sinus volume, ostial diameter and nasal ventilation influence 133-xenon washout in a nose-sinus model. This is important for the interpretation of measurements of 133-xenon washout from paranasal sinuses in healthy subjects and in subjects with sinus disease. The 133-xenon washout was measured with a scintillation camera. The statistical analysis of the results showed that the logarithm (to the base 10) of the half-time of 133-xenon washout is linearly related to the ostial diameter, the sinus volume and the nasal ventilation in the model. In a multiple linear regression model, the most important factor contributing to 133-xenon washout was found to be the ostial diameter, which explained 76% of the variation in log T(1/2). In the same statistical model the sinus volume explained 7.5% and the ventilation 5.3% of the variation in log T(1/2). Calculations of the functional ostial diameter in healthy subjects were made, based on the results of the model study. The mean functional ostial diameter was found to be 3.5 mm (range 0.5-7.5 mm). The results obtained with the present model experiments may be of importance for the correct interpretation of the results of measurements of 133-xenon washout in healthy subjects and patients.

Humans↗
PubMed2001

Paranasal sinus ventilation in healthy subjects and in patients with sinus disease evaluated with the 133-xenon washout technique.

Ventilation of the paranasal sinuses is of great importance in sinus pathophysiology. Therefore, methods of measuring sinus ventilation are important for the evaluation of patients with sinus disease. In the present study, a 133-xenon washout technique was used to evaluate the ventilation of the paranasal sinuses in 34 healthy subjects and in 13 subjects with sinus disease (5 patients with nasal polyposis and 8 patients with chronic sinusitis). For this purpose, a 133-xenon-air mixture was insufflated in each nostril and the washout of the radioactive gas from the paranasal sinuses was monitored with a dynamic single-photon-emission computed tomography camera. The half-time (+/-SD) was found to be 18 +/- 18 minutes for the maxillary sinus, 10 +/- 8 minutes for the frontal sinus, and 18 +/- 23 minutes for the posterior ethmoid and sphenoid sinuses in the healthy subjects. Repeated measurements in 18 of the healthy subjects indicated that the method had acceptable reproducibility according to a Bland-Altman plot. The 133-xenon washout was not influenced by insufflation pressure, nasal patency, or body position. The subjects with sinus disease exhibited half-times of 77 +/- 101 minutes for the maxillary sinus, 91 +/- 124 minutes for the frontal sinus, and 60 +/- 60 minutes for the posterior ethmoid and sphenoid sinuses. For patients with nasal polyposis, the half-time was significantly longer than that in healthy subjects, while patients with chronic sinusitis did not differ from healthy subjects in this respect.

Adolescent↗
PubMed1997

Venous thrombectomy for iliofemoral vein thrombosis--10-year results of a prospective randomised study.

OBJECTIVES: To study if venous thrombectomy prevents late post-thrombotic sequelae, venous obstruction reflux, and improves venous physiology following an acute iliofemoral venous thrombosis. DESIGN: Prospective randomised controlled study. MATERIAL: Thirty patients returned for follow-up 10 years after an acute iliofemoral venous thrombosis initially treated with conventional anticoagulation treatment (medical group, n = 17) or with thrombectomy combined with a temporary arteriovenous fistula and anticoagulation (surgical group, n = 13). Clinical assessment, radionuclide angiography, duplex ultrasound and venous physiology tests were performed. RESULTS: Leg swelling was recorded in 12 (71%) and leg ulcers in three (18%) of the medical patients and in, respectively, six (46%) and one (8%) of the surgical patients. The surgical patients had less severe sequelae (class 0-2). Radionuclide angiography demonstrated that the iliac vein was more commonly occluded following medical (59%) than following surgical (17%) treatment (p < 0.05). Duplex examination demonstrated slightly (n.s.) more reflux in the femoral and popliteal veins in the medical group. Venous physiology (occlusion plethysmography, foot volumetry, and foot vein pressures) did not show any significant differences, although the medical group tended to have a more severe pathology. CONCLUSION: Venous thrombectomy improves venous patency and possibly reduces venous reflux and post-thrombotic sequelae as compared to anticoagulation treatment.

Acute Disease↗
PubMed1992

Ventilation of the paranasal sinuses studied with dynamic emission computer tomography.

This investigation's aim was to study a noninvasive method for determining the ventilation of the nasal sinuses. For this purpose, different insufflation techniques using xenon 133 were tried, along with different scintillation camera techniques. Xenon 133 gas was used for insufflation in the nose and sinuses, and the half-time of the washout curves was determined with the aid of digital scintillation cameras, one of which was capable of dynamic tomography. The tomographic procedure was superior because it made it possible to study the washout from the ethmoidal/sphenoidal sinuses as well. The washout was followed for up to 150 minutes. Great variations in washout were found between different sinuses and also in the same sinus over time. The single photon emission computed tomography (SPECT) technique, which is easy to perform and gives a limited absorbed dose to the patient, seems promising for the future evaluation of sinus ventilation and ostial function.

Absorption↗
PubMed1992

Does nicotine administration influence intragastric acidity?

Smokers have an increased incidence of duodenal ulcer with a high relapse rate whether they receive maintenance therapy with H2-receptor antagonists or not. They also tend to be slow healers. The etiology behind this is still unknown, and there is general disagreement as to whether smoking affects gastric secretion. In an earlier study we found a small but significant decrease in intragastric pH a short time after smoking a cigarette. The aim of the present investigation was to study whether intragastric pH changed during nicotine administration per se. Nicotine was given as a nasal spray to eight healthy smokers. Nicotine did not induce any acute detectable changes in gastric acidity when the 5-min period before spraying was compared with the 35-min period after spraying (median pH, 1.47 (25-75 percentiles, 1.40-2.32) and 1.55 (25-75 percentiles, 1.42-2.06), respectively). When different time periods during a day with hourly nicotine administration were analyzed, and the results compared with those of a similar day when placebo was given, nicotine was found to impair postprandial gastric neutralization. Median pH during the lunch hour was 1.93 (25-75 percentiles, 1.80-2.37) after nicotine and 2.86 (25-75 percentiles, 2.37-3.70) after placebo; p less than 0.025. Possible explanations for this might be nicotine-mediated effects on gastric motility or gastrin release.

Adult↗
PubMed1990

Venous function assessed during a 5 year period after acute ilio-femoral venous thrombosis treated with anticoagulation.

To determine the chronological changes of venous physiology following major thromboses, 20 patients were repeatedly examined for over 5 years after an acute ilio-femoral thrombosis which was treated with conventional anticoagulation. Radionuclide angiography showed that 70% of the patients had obstructive lesions of the iliac vein with only minor changes occurring from 6 months to 5 years. In spite of this, the plethysmographic maximum venous outflow increased from 31 to 45 ml/min/100 ml (P less than 0.001). The foot volumetric reflux did not change with time and about half of the patients had abnormal values. Venous reflux assessed by the refill time of foot vein pressure, deteriorated with time (P less than 0.05), and at 5 years all but one patient had a refill time less than 20 s. The muscle pump function, examined by foot volumetry, was abnormally low in about half of the patients throughout the study. The ambulatory foot vein pressure was constantly pathological (greater than 60 mmHg) in half of the patients and only two of 18 patients had normal values (less than 45 mmHg) at 5 years. Five patients with thromboses involving only the proximal veins had better physiological results than 15 patients with thromboses that extended to the peripheral veins. Three patients who developed venous claudication had iliac vein obstruction and an impaired venous outflow and three patients who developed venous ulcers had venous reflux and severe venous hypertension. Although venous outflow continuously improves following ilio-femoral thromboses, valvular competence and muscle pump function are constantly pathological, creating severe venous hypertension with a risk of post-thrombotic sequelae.

Anticoagulants↗
PubMed1990

Long-term results of venous thrombectomy combined with a temporary arterio-venous fistula.

Forty-one patients with acute iliofemoral venous thrombosis were randomised to conventional anticoagulation or acute thrombectomy combined with a temporary arterio-venous fistula (AVF) and anti-coagulation. Follow-up after 5 years in 22 medical and 19 surgical patients revealed slightly more asymptomatic patients (37 vs. 18%) and less frequent severe post-thrombotic sequelae (16 vs. 27%) in the surgical group (N.S.). The iliac vein was more frequently (P less than 0.05) normal following thrombectomy (71 vs. 30%) as demonstrated by radionuclide angiography, but occlusion plethysmography showed an outflow capacity (61 vs. 45 ml/min/100 ml) that was not significantly better. There was no obvious difference in muscle pump function (EVrel) and reflux (Q/EVrel) assessed by foot volumetry. Still, the ambulatory venous pressure was significantly (P less than 0.05) lower in the surgical group. There was a tendency towards better results following thrombectomy in patients with fresh thrombosis and a successful initial procedure. Although the numbers of observations in many cases were too small to provide statistical evidence of benefit with venous thrombectomy + AVF, this procedure seems to improve the long-term outcome following acute iliofemoral venous thrombosis. Since the difference in outcome is not very striking, anticoagulation treatment is still an acceptable alternative.

Acute Disease↗
PubMed1989

A modified method of curve analysis in foot volumetry and its reference values.

Foot volumetry was introduced by Norgren & Thulesius in 1973 as a non-invasive method of functional evaluation of venous insufficiency. In the following paper we suggest a slightly different method of curve analysis, thus showing the possibility of reducing the methodological error by 30-40%. Based on healthy men and women between 15 and 75 years, new reference values are presented.

Adolescent↗
PubMed1988

Non-invasive recognition of arrhythmogenic right ventricular dysplasia.

Arrhythmogenic right ventricular dysplasia causes ventricular arrhythmias and sometimes heart failure. The condition is easily overlooked, but once suspected, it may be diagnosed non-invasively. This is illustrated by the case reported. The clinical features of this syndrome are discussed, with special emphasis on the non-invasive findings.

Adult↗
PubMed1988

Diagnosis of deep vein thrombosis with a new radionuclide method--99Tcm-albumin test.

The diagnostic efficiency of 99Tcm-albumin test (AT), a new radionuclide method, was evaluated in 90 consecutive patients with suspected deep vein thrombosis (DVT) admitted to the medical emergency ward. Phlebography was used as reference method. The sensitivity of the AT test was 92% and the specificity was 61%. As the method is objective, rapid and convenient for the patients, it can be recommended as an initial examination method to be followed by phlebography, in cases with a positive test result. Criteria with high specificity, 98%, have also been defined but these criteria should be further investigated.

Adult↗
PubMed1988

[Fixation of fractures of the femoral neck using screws or hook-pins. Radionuclide study and short-term results].

In a prospective randomized investigation, AO screws (53 cases) and hook-pins (57 cases) were used for femoral neck fracture fixation in 110 cases. The results of the one-week postoperative scintimetry and a four-month radiographic follow-up were analysed. The femoral head vitality according to scintimetry was similar in the two groups, whether undisplaced or displaced fractures. Within four months from the operation, six cases with screw fixation had been subjected to total hip arthroplasty while only one with hook-pins, all because of fracture redisplacement. However, at the four-month control, another more fracture operated on with screws and five more operated on with hook-pins were scheduled for hip arthroplasty. Thus, no difference between the two methods regarding postoperative femoral head vitality or complications in short term follow-up, was noted.

Adult↗
PubMed1987

Ketanserin in intermittent claudication: effect on walking distance, blood pressure, and cardiovascular complications.

In a 7-center Scandinavian double-blind placebo-controlled study of 179 patients with intermittent claudication, the effect of the serotonin antagonist ketanserin was evaluated on walking distance, brachial and ankle blood pressure, and symptoms. For all centers together, pain-free walking distance was significantly increased after 6 months with both ketanserin (+65%; 71 patients) and placebo (+42%; 78 patients), with no significant difference. However, there was large variability among centers. Classification of "responders" (doubling of walking distance) and patients who deteriorated (decrease of walking distance or dropout for inefficacy) showed significantly more patients responding and significantly fewer patients deteriorating with ketanserin than with placebo. Systemic blood pressure was significantly decreased by ketanserin in hypertensive, but not normotensive, patients, while ankle pressure was unaffected. The incidence and nature of side effects were equal with ketanserin and placebo, but there were more side effects causing dropout in the ketanserin group. An unexpected and possibly important observation was the occurrence of six serious cardiovascular events (myocardial infarction, cerebrovascular complications, and development of rest pain) in the placebo group but none in ketanserin-treated patients. Moreover, there were four additional similar complications in the placebo run-in period. Ketanserin appears to be beneficial in a subgroup of patients with intermittent claudication. A fortuitous finding of this study is that ketanserin might possess a protective effect against thrombovascular complications in patients with intermittent claudication.

Adult↗
PubMed1986

Return to normal of 99mTc-plasmin test after deep venous thrombosis and its relationship to vessel wall fibrinolysis.

Fourteen patients with deep venous thrombosis (DVT) and a positive 99mTc-plasmin test were followed up to determine how soon a negative test was obtained. Localization and extension of the thrombi were determined by phlebography. Plasminogen activator activity in vein walls and local fibrinolytic activity after venous occlusion were measured in order to find out what the prerequisites for impaired thrombolysis are. The time required to obtain a negative 99mTc-plasmin test showed considerable variation, ranging from less than 1 week to more than 6 months. The 99mTc-plasmin test had returned to normal in 64% of the patients after 6 months. No relationship was found between vessel wall fibrinolysis and time to normalization. Instead, we found an association between the time to normalization of the 99mTc-plasmin test and the size of the thrombus, according to phlebography, as well as between the time to normalization of the 99mTc-plasmin test and the extension of leg points with a positive 99mTc-plasmin test at admission. The finding of abnormal 99mTc-plasmin test results more than 6 months after acute DVT is of practical importance and warrants caution when evaluating patients with symptoms and signs suggestive of acute recurrent DVT.

Adult↗
PubMed1986

Follow-up of circulatory changes secondary to deep venous thrombosis with special regards to radionuclide tests.

The influence of circulatory changes, which are secondary to deep venous thrombosis (DVT) in the leg, on result of radionuclide tests was studied in eight patients. Strain gauge plethysmography, a radionuclide blood-pool test and phlebography were performed both in the acute phase and during recovery up to 6 months after the initial admission. Morphological and functional changes were correlated with results from repeatedly performed 99Tcm-plasmin tests, a test currently used for diagnosis of DVT. In the acute phase, the thrombotic leg showed an increase in pooled blood and, in the case of proximal thrombosis, also impaired venous outflow. During the 6-month follow-up complete recanalization was observed in three patients and partial recanalization in five. The circulatory changes were found to recover progressively and earlier than the morphological changes. The 99Tcm-plasmin test was pathological at admission in all patients. It was normalized in parallel with plethysmography and blood-pool test results, at a time when morphological recovery was still incomplete. These findings confirm that a positive 99Tcm-plasmin test reflects haemodynamic changes which are secondary to the DVT rather than a specific binding of the radiopharmaceutical to the thrombus. The 99Tcm-plasmin test was normalized from 1 to more than 26 weeks after an acute DVT. This finding is of practical importance when using radionuclide tests for evaluation of acute recurrent DVT.

Aged↗
PubMed1985

Pulmonary embolism in acute iliofemoral venous thrombosis.

Serial perfusion lung scanning and chest radiography were used to study the incidence of pulmonary embolism in patients with acute iliofemoral venous thrombosis. The efficacy of conventional anticoagulation and surgical thrombectomy in controlling embolism and the risk of creating emboli during thrombectomy were also evaluated. Lung scans obtained on admission in 49 patients were normal in 37 per cent, inconclusive in 18 per cent and positive for embolism in 45 per cent of the patients. Symptoms suggestive of embolism were present in only 24 per cent of the patients and correlated poorly with lung scans. Massive embolism was present in only two patients. Additional, usually asymptomatic, emboli developed within one month in 21 per cent of 29 patients treated conservatively with anticoagulation alone and in 20 per cent of 20 patients having acute thrombectomy combined with a temporary arteriovenous fistula and systemic anticoagulation. Only one conservatively treated patient required caval interruption. Pulmonary embolism, usually of minor degree, is thus present in nearly every other patient with acute iliofemoral venous thrombosis. Anticoagulation alone or in conjunction with thrombectomy and arteriovenous fistula in most cases effectively prevents further embolization and the risk of creating additional emboli by the surgical procedure is insignificant.

Adolescent↗
PubMed1985

Does a computer-based ECG-recorder interpret electrocardiograms more efficiently than physicians?

The quality of ECG-interpretations by a computer-based ECG-recorder has been compared with those carried out visually by physicians in routine clinical practice. Independent reports have been analysed on 474 routine ECGs taken in the medical emergency and out-patient departments, as well as in general practice. Computer reports were available for all of the ECGs, but the physicians had not annotated their interpretations in 11% of them. Eighty-two per cent of the computer-interpretations were adjudged as being satisfactory. The corresponding figure for the physicians' interpretations was 64%. The computer-based ECG-recorder was found to be better than the physician at interpreting ECGs.

Diagnosis, Computer-Assisted↗