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Biomedical subjects

V Kulkarni

Publications and source records attributed to V Kulkarni.

At least 37 records · Page 2Linked to original sources
PubMed1994

Electrical impedance tomography: a review of current literature.

Electrical impedance tomography (EIT) is a relatively new imaging technique that has been developed during the past decade. The electrical properties of tissues are imaged by injecting small currents and measuring the resultant voltages. These voltages are then converted into a tomographic image using a reconstructing algorithm. The method has no known hazards and is relatively inexpensive. There are many possible clinical applications of this technique but apart from gastric emptying, most are still at the research stage as there are various technical and practical problems to be overcome. This paper describes the basic principles of EIT and reviews the English literature to try to assess its potential in clinical imaging.

Algorithms↗
PubMed1993

Comparative evaluation of fixation methods after mandibulotomy for oropharyngeal tumors.

Mandibulotomy for gaining access to the posterior aspect of the oral cavity and oropharynx for excision of tumors has been widely employed for several decades. However, the technical aspects of the procedure continue to evolve. This study compares the complications and bony union rates in a consecutive series of 135 patients undergoing mandibulotomy at 1 institution between 1987 and 1991, using wires and miniplates. The primary tumor sites were oral cavity in 35 patients, oropharynx in 98, and deep lobe of the parotid gland in 2. Twenty-eight patients were previously irradiated, and 62 received postoperative radiotherapy. Thirty-eight patients had a straight-line osteotomy, 31 had step osteotomy, and 66 had notched osteotomy. The fixation of the osteotomy site was done with wires in 59 patients and miniplates and screws in 76 patients. The duration of follow-up ranged from 1 to 5 years. No difference in complications or bony union was observed in patients who underwent repair with wires or miniplates. Due to the number of surgeons and their preferences for different types of osteotomies, as well as the differences in surgical techniques, we further studied the 2 methods of fixation employed by 1 surgeon who performed notched osteotomies on all of his patients (56 patients). Twenty-two underwent repair with wires, and 34 with miniplates. Four patients with wires and seven with miniplates developed wound complications requiring removal of wires in two and miniplates in one. Delayed union or nonunion was not observed in any patient. Fixation with wires or miniplates is equally satisfactory as long as adequate immobilization of the mandibular segments is achieved.

Adolescent↗
PubMed1992

Mudi-chood: an unusual tropical dermatosis.

Mudi-chood is an unusual dermatosis seen in India. It affects the nape of the neck and the exposed part of the upper back in girls and young women. It is characterized by mildly pruritic pigmented papular lesions. It probably represents the comedogenic activity of various oils applied to the hair, which is aggravated by the typical climatic conditions. We present three cases of mudi-chood.

Adolescent↗
PubMed1991

AURA: a new respiratory monitor and apnoea alarm for spontaneously breathing patients.

Previous attempts to introduce non-invasive monitoring of ventilation of spontaneously breathing patients into routine practice have been unsuccessful. The Aberdeen University Respiratory Alarm (AURA) allows such monitoring by utilizing the pyroelectric property of polarized polyvinylidine fluoride sensors to detect temperature changes that occur during breathing into an oxygen delivery face mask. A quartz crystal oscillator generates pulses that allow measurement of interexpiratory time and ventilatory frequency. The system incorporates LED digital displays, a bargraph and audiovisual alarms. An analog output permits display and analysis of the sensed signals. AURA performed satisfactorily in both volunteer studies and six patients in the clinical setting. AURA may be an appropriate respiratory transducer in those patients requiring oxygen therapy.

Adult↗
PubMed1990

ABICUS: ABerdeen Intensive Care Unit System.

Specialised ICUs have improved the care of the critically ill patient, but in doing so produce a deluge of patient data. Microprocessor based systems can optimise both collection and efficient utilisation of such data. In Aberdeen we have developed a general ICU shell which is portable and can be configured to individual ICU needs. The following article describes the Aberdeen ICU System built around this shell.

Expert Systems↗
PubMed1990

Impedence osteography: clinical applications of a new method of imaging fractures.

Fracture healing usually proceeds without difficulty. However, the diagnosis of delayed or non-union is not simple and can present difficulties in management. Normal fracture healing is briefly reviewed along with some methods of assessing the progress of union. The results of using the technique of impedence osteography in a preliminary study of fracture healing are presented. These indicate that the technique can clearly show a fracture and differentiate between normal bone, a united fracture and a non-union.

Diagnostic Imaging↗
PubMed1990

Impedance imaging in upper arm fractures.

We used the Aberdeen impedance imaging system to drive a constant current of 1 mA on a 10 kHz sine wave into the upper arm encircled by an elastic belt of 16 equi-spaced strip electrodes. The system was used to examine a normal upper arm, an upper arm with a recent humeral fracture and an upper arm with a clinically united fracture. We approximated the human upper arm to a circular cylinder and assumed bilateral symmetry of normal human limbs. We measured transverse limb resistivity ratios and reconstructed static two-dimensional images of the spatial distribution of log(resistivity) by the equipotential back projection technique using a homogeneous muscle equivalent saline reference. Our results indicate that impedance osteography provides unique information about the changing electrical characteristics at the fracture site. This information could prove a useful adjunct to clinical and radiological tests for fracture union.

Calibration↗
PubMed1990

AURA: a new respiratory monitor.

The Aberdeen University Respiratory Alarm (AURA) is designed to monitor the respiratory rate and the inter- expiratory period (respiratory gap) in the spontaneously breathing patient using polarised polyvinylidene fluoride sensors incorporated in the Oxygen delivery mask. The monitor is composed of three modules--the sensor module includes a pair of polyvinylidene film strips mounted on the inner surface of the Oxygen mask. The difference in temperature between the ambient Oxygen enriched air and the warmer expired air allows the pyroelectric property of the sensors to be harnessed. The sensor arrangement allows a differential signal to develop between them which is amplified, filtered and rectified prior to triggering a counter. The timing module is based on a 32,768 Hz crystal oscillator that generates pulses allowing the period between expirations to be measured and compared to the maximum allowable period set by the user. The respiratory rate is also measured and compared to the minimum set by the user using EPROMS and comparators. The display module consists of a bar-graph display of the level of the sensed signal with each breath with a soft audible click. Eight segment LEDs are used to provide a digital display of the respiratory rate and the respiratory gap. Audiovisual alarms are triggered when the rate falls short of the set rate and/or when the gap exceeds the set gap. The need for continuous respiratory monitoring of the spontaneously breathing adult in hospital practice led us to develop this prototype with sensors whose design and configuration can be considerably improved.

Adult↗
PubMed1990

Clinicobacteriological study of gas gangrene.

Out of 1040 cases of road side crush injuries 14 cases (1.3%) who developed gas gangrene clinically were studied bacteriologically. Clostridia accounted for 6 (42.86%) cases and non-clostridial anaerobes and aerobes for 4 (28.57%) cases each. Clostridium perfringens was found to be the commonest isolate but non-clostridial anaerobes and aerobes also formed a sizable number. It was concluded that for prevention of gas gangrene a proper surgical toilet and antibiotics at the time of injury were necessary and a smear examination might give a clue to early diagnosis.

Accidents, Traffic↗
PubMed1989

Multiple cold abscesses in a borderline lepromatous patient on multidrug therapy.

A 25-year-old male patient was diagnosed as a case of borderline lepromatous (BL) type of leprosy in erythema nodosum leprosum type reaction. He was put on multidrug treatment. He took regular treatment. Approximately a year after the beginning of the treatment he developed multiple cold abscesses and later tuberculosis of the left hip joint. He was given antitubercular treatment with 4 drugs and the abscesses were treated surgically. He showed good response. This unusual case and the role of intermittent rifampicin is discussed.

Abscess↗
PubMed1989

The Aberdeen Impedance Imaging System.

The Aberdeen Impedance Imaging System is designed to reconstruct 2 dimensional images of the average distribution of the amplitude and phase of the complex impedance within a 3 dimensional region. The system uses the four electrode technique in a 16 electrode split-array. The system hardware consists of task-orientated electronic modules for: driving a constant current, multiplexing the current drive, demultiplexing peripheral voltages, differential amplification, phase sensitive detection and low-pass filtration, digitisation with a 14 bit analog to digital converter (ADC), and -control logic for the ADC and multiplexors. A BBC microprocessor (Master series), initiates a controlled sequence for the collection of a number of data sets which are averaged and stored on disk. Image reconstruction is by a process of convolution-backprojection similar to the fan-beam reconstruction of computerised tomography and is also known as Equipotential Backprojection. In imaging impedance changes associated with fracture healing the changes may be large enough to allow retrieval of both the amplitude and phase of the complex impedance. Sequential imaging of these changes would necessitate monitoring electronic and electrode drift by imaging an equivalent region of the contralateral limb. Differential images could be retrieved when the image of the normal limb is the image template. Better characterisation of tissues would necessitate a cleaner retrieval of the quadrature signal.

Adult↗
PubMed1989

Impedance osteography: a technique to study the electrical characteristics of fracture healing.

The occurrence of a fracture in a limb is accompanied by large changes in the electrical characteristics of the region. Resistivity of bone is more than a hundred times that of bone. The relative permittivities of the two are also different. The fracture site is also known to be electronegative. Electrical Impedance Imaging is capable of reconstructing a two dimensional (2D) representation of the average distribution of amplitude and phase in a three dimensional (3D) region. The spatial resolution in impedance imaging is low, yet the technique is sensitive to properties that are rapidly changing in growing tissues. Though the reconstructed image is an average of a thick slice, this may be of some advantage in impedance osteography precluding the need for imaging multiple planes to cover the extent of the fracture. We used the Aberdeen Impedance Imaging System which uses the 4 electrode technique in a split array, and a current of 1 milliampere on a carrier of 10 kHz to collect a number of data sets. The averaged data sets were used to reconstruct images by the Equipotential backprojection method. In this pilot study we concentrated on the real part of the complex impedance to produce images of log resistivity. The a-priori assumption of bilateral symmetry of human limbs allowed us to reconstruct equivalent regions of the normal and fractured limbs by inverting the electrode array. We obtained static images of the distribution of log resistivity when we used a homogeneous distribution as a reference, and a differential image comparing the fractured to the normal limb. The three patients in our study were at different clinical stages of fracture healing as confirmed by radiography. Our results show the feasibility of using the technique to study and monitor fractures during the healing process.

Bone and Bones↗
PubMed1988

Hypofractionated external radiation with high and low dose rates in the treatment of advanced cancer of the cervix.

Thirteen patients with cancer of the cervix Stage IIIb (heavy) were treated with high (9) and low (4) dose rates, once a week. A total dose of 4200 cGy was delivered over 7 weeks with a fraction size of 600 cGy. Six of nine patients showed complete response following high dose rate hypofractionated radiation. It is felt that synchronization of cells into a sensitive phase during low dose rate radiation is not the determinant of outcome even when duration of treatment is only 5 to 6 hours.

Female↗