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Biomedical subjects

F Madsen

Publications and source records attributed to F Madsen.

117 records · Page 7Linked to original sources
PubMed1975

Emulsion stabilization by non-ionic surfactants: the relevance of surfactant cloud point.

The effect of various additives, electrolytes and non-electrolytes, on the cloud point of non-ionic surfactants has been studied. Additives which salt-out the polyoxyethylene chains of the surfactants cause decreased stability of oil-in-water emulsions by decreasing the true hydrophile-lipophile balance (HLB) of the surfactant; additives such as sodium iodide and propanol salt-in the non-ionic surfactants and result in an increase in the effective or true HLB of the system. The latter additives do not increase the hydration of the polyoxyethylene chains but their effect must be on the structure of water so that the heat of hydration of the chains is altered. Experiments with free films of the aqueous surfactant (Brij 96) show that thinning rates are markedly affected by the additives, but there is little effect on the equilibrium thickness of the films (ca 11 nm). Nonetheless the thickness at the transition from thick film to equilibrium black film decreases with increasing cloud point of the solution indicating increased stability. The importance of structure formation in the liquid film separating the emulsion globules was demonstrated.

Chemical Phenomena↗
PubMedDate not supplied

Hypotensive epidural anesthesia in total knee replacement without tourniquet: reduced blood loss and transfusion.

BACKGROUND AND OBJECTIVES: [corrected] For decades, hypotensive anesthesia has been used in an attempt to reduce intraoperative blood loss. Hypotensive epidural anesthesia (HEA) is a relatively new technique in hypotensive anesthesia. Use of a tourniquet has been shown to be associated with a higher risk of cardiovascular and thromboembolic complications. The effect of HEA on blood loss and need for transfusion in total knee replacement (TKR) is not known. METHODS: Thirty consecutive patients scheduled for TKR were randomized to HEA without tourniquet or spinal anesthesia with the use of a tourniquet (SPI). HEA was performed as an epidurally induced sympathetic block and there was an infusion of low-dose epinephrine to stabilize the circulation. RESULTS: Intraoperative mean arterial blood pressure was 48 mm Hg (HEA) versus 83 mm Hg (SPI) (P <.001). Intraoperative blood loss was 146 mL (HEA) versus 13 mL (SPI) (P <.001). Postoperative blood loss at any time was significantly reduced in the HEA group, and total loss of blood was 1,056 mL (HEA) versus 1,826 mL (SPI) (P <.001). Half of the bleeding took place during the first 3 postoperative hours and 80% during the first 24 hours. In the HEA group, 57% of the patients went through surgery and the hospital stay without receiving blood transfusion versus 19% in the SPI group (P <.05). There was a significantly reduced amount of blood transfusion in the HEA group (193 mL) versus 775 mL in the SPI group (P <.005). No cardiopulmonary, cerebral, or renal complications were registered. CONCLUSIONS: We conclude that HEA is a safe technique that allows TKR without a tourniquet. Compared with spinal anesthesia, the use of HEA for TKR significantly reduces blood loss and the need for blood transfusion.

Aged↗
PubMedDate not supplied

Allergic contact sensitization in an adult Danish population: two cross-sectional surveys eight years apart (the Copenhagen Allergy Study).

In 1990 and 1998 15-41-year-old people were patch-tested in 2 cross-sectional studies of random samples of the population in the western part of Copenhagen County, Denmark. In 1990, 290 subjects and in 1998, 469 subjects were patch-tested. The participation rates were 69% and 51%, respectively. Contact sensitivity to one or more haptens was found in 15.9% and 18.6% in 1990 and 1998, respectively. Nickel sensitivity is still the most common contact sensitivity. The risk of contact sensitivity to the cosmetic-related haptens included in the series (formaldehyde was not included) increased significantly from 2.4% in 1990 to 5.8% in 1998 (odds ratio 2.44, 95% confidence interval 1.04-5.73). The prevalence of contact sensitivity to cosmetic-related allergens has been doubled between 1990 and 1998.

Adolescent↗
PubMedDate not supplied

Comparison between different techniques for measuring nasal patency in a group of unselected patients.

Many techniques for measuring nasal patency have been developed in search for a reliable, easily performed and reproducible method. Rhinomanometry is easily performed in the clinic but daily records of nasal blocking cannot be obtained. In this study we examined the correlation between posterior rhinomanometry (PR), nasal peak flow (nPF), the ratio nasal patency index (NPI), and the opening interrupter method (Rtn) for measuring nasal patency. Twenty-eight subjects with no symptoms of rhinitis and 20 patients with diagnosed rhinitis were investigated. A significant (p less than 0.05) correlation was found between PR and nPF after stratification according to the diagnosis of rhinitis and between nPF, PR, and height. All other correlations tested proved non-significant. We conclude that PR is the method which ought to be used in the hospital, but nPF is an easy way to measure nasal patency and might even be used by the patient at home.

Adult↗
PubMedDate not supplied

Lateral hindfoot instability treated with the Evans tenodesis: a biomechanical analysis.

The stabilizing effect of the Evans tenodesis on movements in the tibiotalocalcaneal joint complex was studied in 10 amputation specimens, using a kinesiologic testing device. The tenodesis was tested following solitary lesion of the anterior talofibular ligament and after combined lesions of the anterior talofibular and calcaneofibular ligaments. All tenodeses were performed with the joint complex in the neutral position. Regardless of the extent of ligamentous damage, the tenodesis frequently restricted adduction and internal rotation to a level below that recorded at intact ligaments. Instability in external rotation in the joint complex and anteroposterior laxity of the talus were never completely reconstructed, regardless of what degree of flexion in the joint complex the tenodeses were tested. The study demonstrates that, if performed with the tibiotalocalcaneal joint complex in the neutral position, the Evans tenodesis cannot reconstruct normal hindfoot kinematics, irrespective of the extent of ligamentous damage. However, severe instability in adduction and internal rotation, both part of clinical supination, were effectively prevented by the tenodesis.

Aged↗
PubMedDate not supplied

Bronchial challenge: a small reservoir for the Wright jet nebulizer.

A small reservoir for the Wright jet nebulizer was constructed and tested with regard to output and particle size characteristics. The Wright nebulizer has found widespread use for bronchial challenge testing. The new small reservoir delivers an aerosol with a size distribution comparable to that delivered from the standard reservoir. Comparable results were obtained when bronchial challenge with either the small or the standard reservoir was performed in 11 patients. The cost for bronchoconstrictor can be reduced by 50-80% by reducing the volume necessary for challenge. It is documented that calibration of the actual set-up is necessary to control the output from a nebulizer, since the output is, not linearly correlated to the flow.

Bronchial Provocation Tests↗
PubMedDate not supplied

Bronchial challenge: ventilation during 'tidal volume breathing' inhalation is not constant.

Standardization of bronchial challenge (BC) in order to improve repeatability of both non-specific and specific challenges is desirable. In the tidal volume breathing BC (tBC), the patient inhales bronchoconstrictor during the entire inspiratory phase of the tidal volume breathing. We determined 2 min ventilation (VE) at each histamine concentration during 187 BCs. Thirty-four patients were challenged twice. We used a standard technique (Cockcroft), except for our patient operated Pari nebulizer. Between-subject (SD = 37%) as well as within-subject (SD = 21%) (p less than 0.01) variations in VE were observed. Furthermore, VE during inhalation of threshold dose (VE-threshold) was smaller than VE during inhalation of the previous dose (VE-threshold-1) (p less than 0.001). For paired differences in VE during two challenges, the within subject SD was 21%. The between subject SD for VE was 32%. VE-threshold was lower in first challenge (p less than 0.001). VE threshold in both challenges was significantly lower than VE-threshold-1. These observations indicate that the respiratory pattern during tBC needs further standardization and that respiratory frequency and inspiratory time during tBC would be worth investigating.

Adolescent↗