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Biomedical subjects

C A Carlsson

Publications and source records attributed to C A Carlsson.

At least 37 records · Page 2Linked to original sources
PubMed1985

The effects of transcutaneous electrical nerve stimulation in patients with severe angina pectoris.

The pain-relieving effects of transcutaneous electrical nerve stimulation (TENS) were investigated in patients with severe angina pectoris first with respect to systemic and coronary hemodynamics and myocardial metabolism during pacing-induced angina and second in a controlled long-term study. Two series of patients with severe angina pectoris (NYHA class III to IV) were studied (13 patients in the pacing study and 23 in the long-term study). In the pacing-induced angina study there was increased tolerance to pacing (142 +/- 23 compared with 124 +/- 20 beats/min tolerated, p less than .001), improved lactate metabolism (2 +/- 36% compared with -18 +/- 43%, p less than .01), and less pronounced ST segment depression (2.3 +/- 1.1 compared with 2.9 +/- 2.6 mm, p less than 0.05) with TENS. In the long study the effects of TENS were measured by means of repeated bicycle ergometer test, frequency of anginal attacks, and consumption of short-acting nitroglycerin. TENS was used regularly for 1 hr three times per day. The TENS treatment group had increased work capacity (637 +/- 308 vs 555 +/- 277 W . min, p greater than .001), decreased ST segment depression (2.3 +/- 1.1 vs 3.6 +/- 1.6 mm, p less than .001), reduced frequency of anginal attacks (p less than .05), and reduced consumption of short-acting nitroglycerin per week (p less than .05) compared with the control group. The observed effects were mainly due to decreased afterload resulting from systemic vascular dilatation.

Adult↗
PubMed1985

Painful scars after thoracic and abdominal surgery.

Painful scars after thoracic or abdominal surgery were treated in 37 patients with various methods, including analgesic block, transcutaneous nerve stimulation (TNS), neurotomy, scar resection, epidural spinal electrical stimulation and thermocoagulation. At follow-up, three patients were free from pain and three experienced significantly less pain as a result of the treatment. In two other patients the pain had spontaneously diminished. The results indicate that surgery on peripheral structures is not effective, which suggests that the source of the pain is to be found in central structures. The authors advocate conservative measures such as blockade, TNS and physiotherapy in combination with psychologic support.

Abdomen↗
PubMed1984

Cortical evoked potentials obtained after stimulation of the lower urinary tract.

Cortical evoked potentials following stimulation of the lower urinary tract have been recorded in humans. Of 26 patients investigated 9 had no urinary signs or symptoms except genuine stress incontinence, while the remaining 17 had various neurogenic bladder disorders. Monopolar and bipolar stimulation of the bladder and urethra was performed using conventional and newly designed suction-type electrodes. While no cortical evoked potentials could be obtained from patients with complete transverse spinal cord lesions polyphasic cortical evoked potentials (N45, P60, N80 and P100 msec.) were recorded in response to monopolar bladder stimulation in all patients with stress incontinence. Following bipolar stimulation a response with lower amplitude and with latencies slightly divergent could be recorded. This response is assumed to be evoked only from bladder afferent nerves, while the monopolar response could include activity from adjacent structures. The most consistent pattern was recorded at the Cz site. Cortical evoked potentials following stimulation of the urethra were more difficult to evoke but they resembled those obtained after bipolar stimulation of the bladder. The method, when fully developed, may be helpful in the clinical investigation of patients affected by various neurogenic disorders of the lower urinary tract. So far, in our limited series a delayed response at P2 has been observed in patients with uninhibited neurogenic bladders.

Adult↗
PubMed1984

Electrical stimulation of the conus medullaris for bladder emptying in a paraplegic.

Nashold et al. (1972) have developed a surgically implantable system for activating the micturition reflex in the paraplegic by electrical stimulation of the spinal cord at the conus level. This communication describes the long-term course in a paraplegic patient who has used conus stimulation to achieve bladder emptying for 7 years. A 42-year-old man sustained a complete transverse lesion at the C6 level. Ten months after the accident he developed some spasticity in his legs but his urinary bladder remained completely flaccid. A device for electrical stimulation of the conus was implanted. This enabled the patient to empty his bladder without significant residual urine. His bladder remained flaccid. Seven years after the implant he developed reflex micturition and he is no longer dependent upon electrical stimulation.

Adult↗
PubMed1984

Energy imparted to the patient in diagnostic radiology: calculation of conversion factors for determining the energy imparted from measurements of the air collision kerma integrated over beam area.

The energy imparted to the patient in diagnostic radiology, related to radiation risk in examinations of the trunk and head, can be deduced from a measurement of the air collision kerma (or exposure) of the incident primary photons integrated over beam area by using a thin, flat ionisation chamber covering the entire roentgen beam. Factors for converting the integral of the air collision kerma to energy imparted to the patient have been calculated using a Monte Carlo method. The patient is simulated by laterally infinite water slabs with thicknesses from 100-300 mm. Calculations are performed for monoenergetic photons (5-300 keV) and energy spectra commonly used in diagnostic radiology (40-130 kV acceleration potential differences and values of the half-value thickness of air collision kerma in aluminium from 0.9 to 9.9 mm). Correction factors which take into account the additional escape of scattered photons from the sides of a laterally finite water slab as a function of field size and focal distance are also given.

Humans↗
PubMed1984

Energy imparted to fluorescent screens from primary and scattered radiation. Variations with atomic composition and screen thickness.

The effects of thickness and atomic composition of fluorescent screens on the impartation of primary and scattered radiation is analysed. Different fluorescent screens give rise to different quotients epsilon p/epsilon s of energy imparted from primary and scattered radiation respectively, due to their variation in atomic composition and thickness. The image contrast in a given radiation field therefore varies with the choice of screen. Energy imparted by primary and scattered radiation in different fluorescent screens has been calculated as a function of tube voltage using a simple analytical model. Comparison of the results for fluorescent screens of different thicknesses with hypothetical screens with both negligible and total absorption has been made. From the results it is evident that the image contrast increases with increased detector thickness if scattered radiation is present. The trends found in the calculations have been confirmed by measurements of the energy imparted from scattered and primary radiation for a number of fluorescent screens including both commercial and specially made screens. Differences in the ratio epsilon p/epsilon s of up to 50% have been measured, and differences reported by other authors are discussed. Their use of detectors with different response to scattered and primary radiation may explain the discrepancies found.

Calcium Compounds↗
PubMed1984

Effective energy in diagnostic radiology. A critical review.

The concept of effective energy, commonly used to characterise the photons in a roentgen beam exhibiting a distribution with respect to energy, is critically reviewed. Definitions are given in terms of equations which clearly demonstrate that values of effective energy depend on the physical quantity with respect to which they are calculated. Examples are discussed which quantify the errors which may result due to incorrect application of effective energy in deriving values for various physical quantities. For instance, the energy imparted to the patient in diagnostic radiology may be underestimated by as much as a factor of two.

Humans↗
PubMed1984

Rhythmic activity in pelvic efferents to the bladder: an experimental study in the cat with reference to the clinical condition 'unstable bladder'.

Efferent nerve activity was recorded from pelvic nerve filaments to the urinary bladder of the cat. At intravesical pressures below 5-7 cm H2O there was no activity, but at higher pressure levels the parasympathetic neurones discharged in 10- to 15-second-long rhythmic bursts separated by silent periods. The frequency of the burst varied from about 1/min at 5 cm H2O to 6-7/min at 15-20 cm H2O. Each burst of activity was followed by a small bladder contraction. The nervous activity preceded the contraction by several seconds, indicating that the bladder response was caused by the efferent discharge. Prolonged continuous efferent activity could occur immediately after pressure changes, at pressures above 20-25 cm H2O or after inhibition caused by intravaginal stimulation. In these situations, rhythmic activity resumed as inhibition of the tonic discharge. This behaviour indicates that the rhythmicity is primarily determined by a central inhibitory mechanism. The findings are discussed in relation to the normal function of the neuronal feedback systems of the bladder and their possible role in the development of the clinical condition 'unstable bladder'.

Animals↗
PubMed1983

Estimation of time as a measure of pain magnitude.

A new method of measuring pain is presented where the patient's estimation of time is used as a pain-related parameter. Pain patients experience a certain time period as increased when compared with pain free control subjects. The increase in time estimation correlates roughly with the clinical estimate of pain severity in different diagnostic groups. Successfully treated patients change their time estimation towards normal. It is considered that this method could be used to evaluate a certain patient's pain and the effectiveness of treatment in relation to the mean time estimate of other patients with the same diagnosis.

Humans↗
PubMed1983

The neurophysiological basis of bladder inhibition in response to intravaginal electrical stimulation.

Intravaginal electrical stimulation (IVS) induces a profound bladder inhibition and is successful in the treatment of incontinence due to detrusor instability. In this experimental study in cats, direct recordings of the efferent activity in thin hypogastric and pelvic nerve filaments to the bladder were used to analyze the neuronal mechanisms underlying this bladder inhibition. A longlasting reflex discharge, with a latency of 35 to 50 msec., was evoked in the hypogastric nerve by IVS. The reflex discharge was unaffected by imposed changes in intravesical pressure or by micturition contractions, but the response was very frequency-sensitive with an optimal transmission at about 5 Hz of stimulation. A "spontaneous" efferent activity could be recorded in the pelvic nerve filaments when the bladder pressure was elevated above 5 to 7 cm. H2O. The pelvic activity occurred in 10 to 20-second bursts, each followed by an abortive detrusor contraction. IVS of 5 to 10 Hz completely abolished this efferent pelvic activity by central inhibition. The findings are discussed in relation to the normal neuronal control of the bladder and to the clinical application of IVS.

Action Potentials↗
PubMed1982

Cortical evoked potentials following stimulation of the urinary bladder in man.

Techniques are described for recording evoked potentials in humans in response to stimulation of the urinary bladder. Twenty patients with various disorders of their urinary function were investigated. Evoked cortical potentials following stimulation of the urinary bladder could be recorded from all patients except subjects with complete transverse spinal cord lesions. The response was most evident at the central site (Cz) and had its most prominent peaks at 45, 65, 82 and 102 msec. This technique may become a useful diagnostic tool in the study of neurogenic bladder dysfunctions.

Aged↗
PubMed1980

Electrical stimulation in interstitial cystitis.

We treated 14 women with chronic interstitial cystitis with long-term intravaginal or transcutaneous nerve stimulation. Clinical and urodynamic evaluations were done after 6 months to 2 years. Improvement was not immediate but required a considerable period of continuous, daily use of electrical stimulation. The results were favorable--a substantial decrease in pain and frequency of micturition in all patients after long-term treatment. Since the methods seem effective and are simple, cheap and non-destructive electrical stimulation is recommended for all patients with chronic interstitial cystitis.

Aged↗