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Biomedical subjects

M Bengtsson

Publications and source records attributed to M Bengtsson.

At least 127 records · Page 7Linked to original sources
PubMed1985

Skin conductance responses during spinal analgesia.

Skin conductance responses (SCR, "sympatho-galvanic reflex") were measured before and during spinal analgesia in 17 patients scheduled for transurethral surgery. Responses were provoked by standardized electrical stimulation over the clavicle opposite to the recording side; alternatively, a short deep breath, pinching, verbal stimuli or sharp sounds were used. Measuring sites (two electrodes 6 cm apart) were the hand, levels T5, T9, T12-L1 and the foot. Spinal analgesia reached a median cephalad level of T4 (mean T4, range +/- 3 segments) 20-25 min after injection. SCR was markedly depressed in the foot in 15 of 17 patients, at T12-L1 in 12 of 17, at T9 in 10 of 17, at T5 in 9 of 16 and in the hand in 6 of 17. Total abolition of the SCR in the foot was accomplished in only seven cases and sympathetic activity reappeared long before regression of analgesia or motor blockade was observed. In four cases of five with an analgesic level T1-T2, the SCR was preserved in the hand. No consistent correlation between blood pressure change and SCR-change was seen. The conclusion from this study is that preganglionic sympathetic B-fibres are more difficult to block than A-fibres during spinal analgesia. The duration of sympathetic blockade was far shorter than analgesia and motor blockade. Thus, sympathetic blockade during spinal analgesia seems to be far less extensive than that described in the literature.

Aged↗
PubMed1984

Can the "sympatho-galvanic reflex" (skin conductance response) be used to evaluate the extent of sympathetic block in spinal analgesia?

The skin conductance response (SCR) (the "sympatho-galvanic reflex") was studied in volunteers and in a few patients undergoing spinal analgesia. Electrical stimulation over the clavicle, breath-holding during inspiration, a short, deep breath and a sharp sound provoked a marked change in conductance not only in the hand and foot but also in dermatomes T5, T9, T12-L1. Thus, the SC response can be used to study sympathetic activity not only in the hand and foot, but also on the chest and abdomen. Electrical stimulation over the clavicle or a short, deep breath were the best means of provoking SC responses in patients receiving spinal analgesia. This restricted pilot study indicates that skin conductance response is maintained at dermatome levels far below anaesthetised levels during spinal analgesia, and a larger study is now under way to investigate these results further.

Abdomen↗
PubMed1984

Spinal analgesia with glucose-free bupivacaine--effects of volume and concentration.

Spinal analgesia using 22.5 mg glucose-free bupivacaine, given either as 3.0 ml of 0.75% solution or 4.5 ml of 0.5% solution was studied in a double-blind fashion in 40 patients scheduled for transurethral surgery. No differences in onset, duration and regression of analgesia or motor blockade were noticed, indicating that dosage (in mg) is more important than either volume or concentration when glucose-free bupivacaine solutions are used for spinal analgesia. The cardiovascular effects were small and no side-effects attributable to the spinal anaesthetic were seen.

Aged↗
PubMed1984

Changes in skin blood flow and temperature during spinal analgesia evaluated by laser Doppler flowmetry and infrared thermography.

Changes in skin blood flow and skin temperature during spinal analgesia and "sham" spinal analgesia were studied using laser Doppler flowmetry and skin temperature measurements on patients scheduled for transurethral resection. Infrared thermography was also used. During "sham" spinal analgesia skin blood flow decreased 17.7% +/- 37% (s.d.) and skin temperature fell 0.05 degrees C +/- 0.6 (s.d.) degree C. The height of the blockade was T10 or above in all cases. Using the laser Doppler technique with measuring points from the clavicle to T12, a tendency towards increased skin blood flow was seen in six cases out of 20 at T10 (significant elevations in 3/20) and in 14 cases out of 20 at T12 (significant elevations in 7/20). Skin temperature measurements and thermography showed a tendency towards cooling in the thoraco-abdominal region in the vast majority of the cases and a marked temperature elevation in the foot only. No differences between hyperbaric and glucose-free solutions for spinal analgesia were noticed. The conclusion of this study is that during spinal analgesia the extent of sympathetic blockade is less than the extent of analgesia.

Aged↗
PubMed1983

Regulation of carcinogen metabolism in the rat ovary by the estrous cycle and gonadotropin.

The activity of 7,12-dimethylbenz[a]anthracene hydroxylase in the rat ovary is several times higher in the proestrous phase of the estrous cycle than in the estrous and metestrous plus diestrous phases. Administration of gonadotropin leads to a similar increase in the capacity of the ovary to metabolize xenobiotics. This variation in the activity of 7,12-dimethylbenz[a]anthracene hydroxylase during the estrous cycle may be related to the marked changes in the incidence of ovarian cancer during menopause and in women taking contraceptive pills.

Animals↗
PubMed1983

The effect of spinal analgesia on skin blood flow, evaluated by laser Doppler flowmetry.

Changes in skin blood flow provoked by spinal analgesia were evaluated by laser Doppler flowmetry. This method permits a continuous and noninvasive measurement of the microvascular flow in the superficial skin layer. All recordings were made under control environmental conditions on 40 patients submitted to transurethral resection. During spinal analgesia a significant (P less than 0.001) reduction in skin blood flow was obtained in the shoulder and chest, while an increase (P less than 0.001) in skin blood flow was seen in the lower part of the body. In the postoperative period these changes still persisted, although they were less significant, indicating the individual duration of analgesia. The relations between intra-individual relative changes in skin blood flow and skin temperature during spinal analgesia were found to be virtually uncorrelated. Laser Doppler flowmetry seems to be a useful tool in the further evaluation of the influence of spinal analgesia on the extent of the associated sympathetic blockade.

Aged↗
PubMed1983

Spinal analgesia with bupivacaine, mepivacaine and tetracaine.

Spinal analgesia with bupivacaine, tetracaine and mepivacaine was studied in 103 patients in two studies, one open and one double-blind. Injections were given with the patients sitting and they remained seated for 2 min after the injection. Regardless of the agent used, the mean cephalad spread of analgesia was T6-8 15 min after injection. Mepivacaine 4% (60 mg) in glucose produced analgesia and motor blockade of good quality but of short duration. Bupivacaine 0.5% and 0.75% and tetracaine 1%, all solutions with glucose, produced long-lasting blockades, tetracaine 14 mg having a longer duration of action than 15 mg bupivacaine. When 15 mg of bupivacaine was administered in solutions containing glucose, no difference in sensory blockade was seen, regardless of volume (2 or 3 ml, 0.75% and 0.5%, respectively) injected. 3 ml of bupivacaine 0.75% (22.5 mg) in glucose-free solution produced a very long-lasting blockade with deep motor engagement, particularly suitable for hip surgery of long duration. Bupivacaine 0.75% (3 ml, 22.5 mg) in solution with glucose produced a more marked effect on the blood pressure than the other solutions tested.

Age Factors↗
PubMed1983

Adjuvant intravenous sympathetic block with guanethidine in construction of arteriovenous fistulas for blood access.

A prospective randomized investigation of regional intravenous sympathetic block with guanethidine (RGB) was made in patients undergoing surgical construction of arteriovenous fistula (AVF) for vascular access. The blockade was preoperatively performed on chronically uraemic patients without previous vascular access surgery. The studied data were preoperative forearm blood flow, intraoperative fistula blood flow and flow resistance, and patency rates of AVF. Serial occlusion plethysmography showed a 152% increase in mean forearm blood flow in the RGB group, with significant (p less than 0.001) difference from the controls. The fistula blood flow resistance was decreased (p less than 0.05). The early failure rate was 1/17 among the patients treated with RGB and 3/17 in an otherwise comparable control group. RGB may be useful for reducing early failure rates after construction of AVF, by facilitating blood flow through the fistula.

Adolescent↗
PubMed1982

Metabolism of polycyclic aromatic hydrocarbons and covalent binding of metabolites to protein in rat adrenal gland.

The metabolism of the carcinogenic and adrenocorticolytic polycyclic aromatic hydrocarbon 7,12-dimethylbenz(a)anthracene in rat adrenals was investigated. Both 7,12-dimethylbenz(a)anthracene and benzo(a)pyrene, which also is a well-known carcinogen but has no short-term effects on rat adrenals, appear to be metabolized by one common type of cytochrome P-450-dependent monooxygenase localized in the endoplasmic reticulum. Studies of the kinetic properties of this cytochrome P-450 reveal that the Km values for 7,12-dimethylbenz(a)anthracene and benzo(a)pyrene are lower than 3 microM. Identification of metabolites indicates that, with both 7,12-dimethylbenz(a)anthracene and benzo(a)pyrene, phenols and diols were formed the relative rates of formation of which were markedly influenced by the expoxide hydrase inhibitor cyclohexane oxide, suggesting that epoxides are intermediate metabolites. Added or endogenous microsomal glutathione S-transferase B had little or no effect on the distribution of metabolites. A rather selective binding of metabolites of 7,12-dimethylbenz(a)anthracene to soluble and microsomal proteins was demonstrated. The adrenal cytochrome P-450 involved in the conversion of these polycyclic aromatic hydrocarbons appears to be unrelated to those responsible for the synthesis of mineralocorticoids and glucocorticoids from cholesterol. Among androgens and estrogens, estradiol proved to be the most inhibitory steroid, suggesting a role of the hydrocarbon-metabolizing cytochrome P-450 in estrogen biosynthesis. However, no such function could be demonstrated conclusively. The metabolite patterns and the effects of nonsteroid inhibitors of liver monooxygenases, e.g., alpha-naphthoflavone, SU 9055, and ellipticine, suggest that the properties of this cytochrome P-450 resemble those of the 3-methyl-cholanthrene-inducible cytochrome P-488 from rat liver.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1982

Changes in human forearm blood flow after intravenous regional sympathetic blockade with guanethidine.

The effect of intravenous regional sympathetic blockade with guanethidine on total forearm blood flow and on muscle and skin blood flow in the forearm was studied in healthy humans, using venous occlusion plethysmography, 133Xe-clearance technique and skin temperature recordings. The total blood flow tripled in response to the blockade and the rise persisted for 2-3 days. The increase in blood flow was confined to the skin, with no demonstrable steal effect on muscle blood flow. The observations imply that this type of sympathetic blockade may be of therapeutic value in some vascular disorders of the hand, and as supportive treatment in vascular surgery on the extremities.

Adult↗
PubMed1976

Demonstration of 3-methoxytyrosine in the urine of melanoma patients.

With the aid of gas chromatography and mass spectrometry a metabolite of dopa, 3-methoxytyrosine, has been demonstrated in the urine of 2 patients with melanoma metastases, the amounts excreted being 4.0 mg and 8.5 mg/24 hours, respectively. 3-Methoxytyrosine could not with certainty be identified in the urines of two normal subjects.

Chromatography, Gas↗