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Biomedical subjects

S A Davidson

Publications and source records attributed to S A Davidson.

11 recordsLinked to original sources
PubMed1992

Lymph node sampling in patients with epithelial ovarian carcinoma.

Lymph node sampling is part of the FIGO staging of patients with ovarian carcinoma and is usually part of a meticulous second look operation. We analyzed the primary lymph node status of patients and compared this to the lymph node status at second look operation. From 3/86-3/91, 97 patients with epithelial ovarian tumors were treated at this institution. Seventy-one of the 97 patients (73.2%) had lymph node sampling at primary surgery. Thirty of the 71 patients had positive lymph nodes (42.2%) and 41 patients were lymph node negative (57.8%). Of the initial 97 patients, 58 were eligible for second look operation (59.8%), and 48 of these patients had lymph nodes sampled at second look operation. Nine of the 48 patients had positive lymph nodes (18.7%) and 39 had negative lymph nodes at second look operation (81.3%). Of the patients with negative lymph nodes at primary surgery, 25 patients had second look operation and 24 of these patients had lymph node sampling at second look operation. All patients with negative lymph nodes at primary surgery had negative lymph nodes at second look operation. Of the 30 patients with positive lymph nodes at primary surgery, 12 underwent second look operation. Four patients had persistent positive lymph nodes and 8 patients had negative lymph nodes. Our data suggest that patients with negative lymph nodes at primary surgery are unlikely to have positive lymph nodes at second look operation. Therefore, we believe that lymph node sampling under these circumstances is unnecessary.

Adolescent↗
PubMed1991

Intraperitoneal chemotherapy: analysis of complications with an implanted subcutaneous port and catheter system.

To determine the morbidity associated with delivery of intraperitoneal chemotherapy via subcutaneous semipermanent infusion catheters, we analyzed the data on 227 patients treated from April 1985 through December 1989. A total of 249 catheters were inserted and used to administer chemotherapy in these patients. There were 40 (17.6%) complications associated with the use of 230 original catheters, with 20 patients experiencing catheter inflow obstruction and 20 developing catheter-related infections; the latter group included 8 patients with bowel perforations. Although there was a trend toward an increase in catheter-related infections in association with large bowel surgery and appendectomies, sample size limited statistical analysis. There were 7 (36.8%) complications associated with the use of 19 replacement catheters. This rate was significantly increased (P = 0.03) when compared with the complication rate of original catheters. This system functions well and has an acceptable level of morbidity for delivery of intraperitoneal chemotherapy in gynecologic cancer patients.

Catheterization↗
PubMed1991

Determining latency and amplitude for multiple peaked P300 waveforms.

The P300 is characterized by a large positive peak occurring approximately 300 msec post stimulus onset. When a single peak is present, the P300 latency is easily identifiable. However, in cases where the P300 waveform is broadly or multiply peaked, ambiguity exists when attempting to determine the latency of the waveform. Amplitude, while less ambiguous, has also been variously measured as baseline to peak, or peak-to-peak, using either N200 or N300 as the trough. The present study was undertaken to evaluate a method for precisely and consistently determining the latency and amplitude characteristics of the P300 waveform. Three independent raters examined 40 records to determine P300 latency and amplitude according to prescribed criteria. Results indicated that the suggested techniques yield good inter-rater agreement on the latency and amplitude characteristics of the P300 waveform regardless of P300 morphology.

Adult↗
PubMed1990

Preliminary studies on the use of an ABR amplitude projection procedure for hearing aid selection.

Hearing aid selection in young nonverbal children is difficult and objective selection procedures are needed. Kiessling (Scand Audiol 1982;11:269-275; Arch Otorhinolaryngol 1983;238:233-240) has proposed an objective hearing aid selection method based on an unaided ABR amplitude projection procedure. However, Kiessling's ABR projection method is based on the assumption that ABR amplitude is directly related to the loudness of a signal--an assumption which has not been tested. This assumption was investigated in a group of ten normally hearing and three hearing-impaired listeners. The results indicated that ABR amplitude measures obtained in a single trial do not always correlate well with perceived loudness, but ABR amplitudes averaged over several trials do correlate well with estimates of perceived loudness. The hearing-impaired listeners then participated in a second phase of the investigation in which hearing aids chosen by the ABR projection procedure were compared with hearing aids chosen by more conventional methods. The results indicated that the projection procedure prescribed appropriate gain and compression characteristics for two of the three hearing-impaired listeners.

Adult↗
PubMed1990

Reclosure of disrupted abdominal incisions.

We evaluated prospectively a technique of delayed reclosure of disrupted abdominal incisions. Forty-one consecutive postoperative obstetric and gynecologic patients with abdominal incisions that had opened because of infection, hematoma, or seroma and had intact fascia participated in the study. All wounds were first managed identically, with surgical drainage and debridement, for a minimum of 4 days. The patients then were randomized to either wound reclosure by a standardized en bloc technique (35) or healing by second intention (six). Reclosure was successful in 30 of 35 cases (85.7%). The mean time to complete healing was 15.8 days in successful cases, 67.2 days in failed cases, and 23.2 days for all patients who were reclosed. Failure to heal after reclosure was due to subcutaneous infection in two patients and seroma in three; these women were significantly heavier than those in whom reclosure was successful. There were no other major complications of wound reclosure. Patients randomized to healing by second intention required a mean of 71.8 days of wound care. The time to complete healing in the wound-reclosure group was significantly shorter compared with the group that healed by second intention (P = .002, log rank test). We conclude that en bloc reclosure of disrupted surgical incisions, compared with nonsurgical treatment, significantly decreases the time required for wound healing and has minimal morbidity.

Adult↗
PubMed1990

Treatment failure in endometrial carcinoma.

Endometrial carcinoma has been regarded as one of the more curable gynecologic malignancies. Clinical stage, grade, and depth of myometrial invasion are well-established prognostic variables. We examined the clinical course of 520 patients with endometrial carcinoma treated at Walter Reed Army Medical Center and the Naval Hospital, Bethesda, Maryland, between January 1, 1960 and December 31, 1982. Life table 5-year survivals for stages Ia, Ib, II, III, and IV were 89, 92, 77, 27, and 0%, respectively. Compared with patients with grade 1 endometrial adenocarcinomas, significant decreases in survival were noted for patients with grade 2 or 3 endometrial, papillary endometrioid, serous papillary, and clear-cell tumors. There were six treatment-related deaths (1.2%). Thirty-eight patients (7.3%) developed recurrent disease, with a median time to recurrence of 15 months and a median survival of 21 months. Two of 11 patients with pelvic recurrence were salvaged by radiotherapy, whereas none of 27 patients with distant failure survived. Sixteen advanced-stage patients (3.1%) with persistent disease had a median survival of 4.5 months. Patients with advanced disease or unfavorable histologic subtypes responded poorly to conventional therapy. Current salvage treatments are largely ineffective. Combined-modality therapy and systemic adjuvant therapy should be prospectively evaluated in high-risk patient subgroups.

Adenocarcinoma↗
PubMed1989

Presentation level determination for CV tokens using a computer-controlled adaptive procedure.

The feasibility of using a computer-controlled adaptive procedure to find maximum monotic performance for consonant-vowel (CV) stimuli was evaluated and compared to the procedure typically used to determine a performance-intensity function in two experiments. In experiment I, the computer-controlled adaptive procedure and the typical manual procedure were evaluated on 26 normally hearing listeners. Results indicated that the shape of the performance-intensity functions was similar for both procedures with the computer-controlled adaptive procedure selecting a higher presentation level. The test-retest reliability for the computer-controlled adaptive procedure was good with a mean difference on retest of 1.2 dB. In experiment II, the same procedures were evaluated using 9 sensorineural hearing impaired subjects. Again similar configuration between functions was observed. The primary advantage of the computer-controlled adaptive procedure for both subject groups is efficiency in terms of time of administration and number of CV stimuli used.

Adolescent↗
PubMed1988

A clinically feasible method for determining frequency resolution.

Psychophysical tuning curves were generated by normally hearing and hearing-impaired subjects using two methods; a detailed laboratory method and a Bekesy method proposed as suitable for clinical use. The two methods were compared for stability, the amount of masking produced and the pattern of the masking functions. The two measures of frequency resolution were found to be equally reliable and showed the same range of repeatability as simple pure tone thresholds. The patterns of the masking functions were similar regardless of the method used. However, the absolute amounts of masking indicated with each method were significantly different, with more masking obtained when the clinical method was used.

Adult↗