Biomedical subjects

A A Kumar

Publications and source records attributed to A A Kumar.

57 records · Page 4Linked to original sources

PubMedDate not supplied

Electrical impedance cardiography using artificial neural networks.

This study evaluates the use of artificial neural networks to estimate stroke volume from pre-processed, thoracic impedance plethysmograph signals from 20 healthy subjects. Standard back-propagation was used to train the networks, with Doppler stroke volume estimates as the desired output. The trained networks were then compared to two classical biophysical approaches. The coefficient of determination (R2 x 100%) between the biophysical approaches and the Doppler was 8.20% and 9.90%, while it was 77.38% between the best neural network and the Doppler. Among these methods, only the neural network residuals had a significant zero mean Gaussian distribution (alpha=0.05). Our results indicate that an invertible relationship may exist between thoracic bioimpedance and stroke volume, and that artificial neural networks may offer a potentially advantageous approach for estimating stroke volume from thoracic electrical impedance, both because of their ease of use and their lack of confounding assumptions.

Adult↗

PubMedDate not supplied

Cost and efficiency of HIV voluntary counselling and testing centres in Andhra Pradesh, India.

BACKGROUND: [corrected] As part of the effort to control HIV/AIDS, the number of HlV voluntarycounselling and testingcentres (VCTCs) is increasing rapidly in the public health system of the Indian state of Andhra Pradesh, which is estimated to have one of the highest rates of HIV infection in India. However, systematic data on the cost and efficiency of providing VCT services in India are not available to help guide efficient use of resources for these services. METHODS: We used standardized methods to obtain detailed cost and output data for the 2002-03 fiscal year from written records and interviews in 17 VCTCs in the public health system in Andhra Pradesh. We calculated the economic cost per client receiving VCT services, and analysed the variation and determinants of total and unit costs across VCTCs. We used multivariate regression techniques to estimate incremental unit costs. We assessed hurdles towards serving an optimal number of clients by VCTCs. RESULTS: In the 2002-03 fiscal year, 32 413 clients received the complete sequence of services at the 17 VCTCs, including post-HIV test counselling. The number of clients served by each VCTC ranged from 334 to 7802 (median 979). The overall HIV-positive rate in post-test counselled clients was 20.5% (range 5.4%-52.6%). The cost per client for the complete VCT sequence varied 6-fold between VCTCs (range Rs 141.5-829.6 [US 2.92-17.14 dollars], median Rs 363.5 [US 7.51 dollars]). The cost per client was significantly lower at VCTCs with more clients (p < 0.001, R2 = 0.83; power function) due to substantial fixed costs. Personnel made up the largest component of cost (53.7%). The cost per client had a significant direct relation with percent personnel cost for VCTCs (p < 0.001, R2 = 0.58; exponential function). A multiple regression model revealed that the incremental cost of providing complete VCT services to each HIV-positive and -negative client was Rs 123.5 (US 2.54 dollars) and Rs 59.2 (US 1.22 dollars), respectively. Fourteen VCTCs (82.4%) reported that they could serve more clients with the available personnel and infrastructure, and that inadequate demand for their services was the main hurdle towards achieving this. CONCLUSION: These data suggest that the efforts of the National AIDS Control Organisation of India and the Andhra Pradesh State AIDS Control Society in increasing VCTCs could yield even higher benefit if the demand for these services was enhanced, as this would increase the number of clients served and reduce the cost per client. Ongoing systematic cost-efficiency analysis is necessary to help guide efficient use of HIV-control resources in India.

AIDS Serodiagnosis↗

PubMedDate not supplied

Cryosurgery of prostate cancer. Use of adjuvant hormonal therapy and temperature monitoring--A one year follow-up.

OBJECTIVE: To determine the clinical outcomes at one year of Stages T2-T3 prostate cancer by cryosurgery utilizing pretreatment with total androgen ablation therapy and temperature monitoring to control the freezing process. Study Group To date, 347 patients have had 356 cryosurgical procedures, 280 have reached one year post treatment. Of these 131 had re-evaluation with prostatic biopsy and serum PSA. METHODS: Transrectal ultrasound (TRUS) measurement of tumor size and biopsy of extraprostatic space was used to stage patients into two main groups: confined (66.6%) versus nonconfined (19.3%). Radiation failures (14.1%) formed a separate group. Failure rates for the 131 men include all cancer diagnosed during the one year period following cryosurgery. RESULTS: The one year failure rate for the study group was 19.8% (26/131). For stages T2a, T2h C, T3 and radiation failures, the rates of positive biopsies were 13.9%, 12.9%, 33.3% and 35%, respectively. For those with local control of cancer (negative biopsy), 80% had prostate specific antigen (PSA) levels of < 0.5 ng/ml. The statistical variables for persistent cancer with prostate specific antigen > 0.5 ng/ml were: sensitivity of 66.7%, PPV of 16.7%, NPV of 98% and specificity of 83.7%. A statistically significant difference exist between stages T2 vs T3 and radiation failures (p = < 0.5). Major complications of rectal fistula and total incontinence for previously non-treated cancer versus radiation failures were 0.33% and 8.7% respectively, a 26 times greater risk. CONCLUSION: Results of cryosurgery for all stages of prostate cancer at one year are encouraging, being 80% free of disease (biopsy and prostate specific antigen). The morbidity of the previously non-treated cancers from this procedure for us was minimal with high patient acceptance. For radiation failures a local control rate of 65% was achieved. However, early in our experience significant morbidity did occur and our enthusiasm for attempted salvage was initially tempered.

Aged↗