Biomedical subjects

Darrell Allen

Publications and source records attributed to Darrell Allen.

5 recordsLinked to original sources

PubMed2005

Defining the learning curve for percutaneous nephrolithotomy.

PURPOSE: To define the learning curve for percutaneous nephrolithotomy (PCNL) using three potential surrogate markers of surgical expertise. MATERIALS AND METHODS: The learning curve of an endourologist with no previous experience at performing solo PCNL was studied. Three putative parameters of expertise were reviewed, namely, operating time, fluoroscopic screening time, and radiation dose. Operations were analyzed in cohorts of 15 to determine when a plateau was reached for all three variables. Comparison was then made with the results of a surgeon who had performed more than 1600 PCNLs. Stone type and stone clearance rate were also noted. RESULTS: The mean operating time of the novice surgeon fell to a plateau of 92 minutes after 60 cases, but screening time and radiation dose did not plateau until case 115, when values of 231 seconds and 406 cGy/cm2 were recorded, respectively. The senior surgeon had a mean operating time of 98 minutes and screening parameters equivalent to those of the novice surgeon after 115 cases. The complexity of the stones tackled grew with increasing experience, although stone-free rates remained constant. CONCLUSIONS: This study of the learning curve of a single surgeon suggests that competence at performing PCNL is reached after 60 cases and excellence after 115. Radiation parameters are a valuable tool in the assessment of operative competence.

Clinical Competence↗

PubMed2004

The two-week-wait cancer initiative in urology: useful modernization?

The two-week-wait cancer initiative in the UK was designed to speed referral of patients suspected of having cancer and, by so doing, improve their outcome. We reviewed the case notes of all patients referred under this scheme to a single urology department over twelve months. In the department, nearly one-third of new outpatient appointments came under this scheme. 124 patients were referred and all but 7 were seen within the 14-day deadline. In 62 the reason for referral was haematuria, which was macroscopic in 42. Of those with macroscopic haematuria 6 proved to have cancer, newly diagnosed in 4 (2 bladder, 2 renal); no patient with microscopic haematuria had cancer. Of 35 referred with a raised prostate-specific antigen 11 had prostate cancer, in most cases beyond cure. Cancer was found in 1 of 19 patients referred with a testicular mass. In patients referred under the two-week-wait scheme with macroscopic haematuria, cancer is common. Microscopic haematuria is seldom significant. Carcinoma of the prostate is usually advanced and beyond cure at presentation. Among patients referred with scrotal lumps, cancer of the testis is not common. The scheme as a whole is unlikely to improve cancer outcomes. Patients with macroscopic haematuria might be better served by one-stop clinics. For those with testicular lumps, most of which will be benign, the best answer might be direct general practitioner access to scrotal ultrasonography.

Adult↗

PubMed2004

Role of cell-free plasma DNA as a diagnostic marker for prostate cancer.

Recent evidence has shown elevated levels of cell-free plasma DNA in cancer patients. The aim of the present study was to quantify and compare the levels of cell-free plasma DNA in patients with prostate cancer, prostatic intraepithelial neoplasia (PIN), and benign prostatic hypertrophy (BPH) to examine if it offered a useful diagnostic test. Blood samples were obtained from 37 patients attending a clinic for prostate biopsies. Samples were taken prior to biopsy, within 1 hour of the biopsy, and then 2 weeks later. DNA was extracted using a QIAamp blood kit (Qiagen) and plasma DNA measured, in genome equivalents/milliliter plasma (GE/mL), using real-time quantitative PCR for the beta-globin gene. Prior to biopsy, plasma DNA concentration in BPH patients was 936 GE/mL (median; range: 633-2074 GE/mL), while cancer and PIN patients had significantly higher levels of DNA at 1734 GE/mL (median; range: 351-3131 GE/mL; P = 0.01) and 1780 GE/mL (median; range: 1514-2732 GE/mL; P = 0.04), respectively. Comparison of plasma DNA concentration before and after biopsy showed that 60 minutes after biopsy values were significantly higher in both BPH (1494 GE/mL; range: 613-2522 GE/mL; P = 0.029) and cancer (2758; range: 1498-5226 GE/mL; P = 0.007) patients. ROC analysis of the data indicated a sensitivity of 85% and a specificity of 73% when DNA concentration of 1000 GE/mL was taken as an indicator of malignancy or PIN. The data suggest that quantification of cell-free plasma DNA may have an important diagnostic role in distinguishing benign and malignant prostate disease.

Adenocarcinoma↗

PubMed2003

Baskets in the kidney: an old problem in a new situation.

A potential complication of using a zero-tip basket to remove stones from a lower-lower pole calix of the kidney is impaction in this position. We report an endourologic technique involving a hydrogel-coated ureteral dilator to facilitate closure of the wires and removal of the basket following lithotripsy to fragment the stone.

Adult↗

PubMedDate not supplied

Survival and quality of life after cardiac surgery complicated by prolonged intensive care.

AIM: To determine survival, factors determining survival and evaluate quality of life (QOL) after 1 year, in patients who had prolonged intensive care unit (ICU) stay after cardiac surgery. METHODS: In the year 2001, 804 patients underwent various cardiac procedures utilising cardiopulmonary bypass (CPB). Eighty-nine consecutive patients requiring ICU stay of > or = 5 days constituted the study group, majority of these suffered from multiorgan failure (> 2 organ systems). Survival was determined in the study group after 1 year. Patients with an uncomplicated postoperative course were matched to the survivors in the study group with respect to age, gender, type of surgery, risk scores, and duration of follow-up and constituted the control group. The, Short Form Health Survey was used to assess QOL at the end of 1 year in these patients. QOL was compared between the study group and the control group and to that of general population. RESULTS: Seventy percent of the patients in the study group suffered from failure of at least three organ systems. Mean ICU stay was 13 +/- 3 days (median nine, maximum 53). At the end of 1 year the mortality in the study group was 34%. The independent predictors of mortality were: preoperative cardiac support, lower ejection fraction, higher Parsonnet score, higher Euroscore, pulmonary complications, renal failure necessitating hemofiltration, CNS complications, and failure of three or more organ systems. The QOL was lower in the study group than the control group in all eight dimensions measured (significant in five p < 0.05): Physical function, Role physical, Vitality, Mental health, General health, and Bodily pain. CONCLUSION: One year mortality in patients with prolonged ICU stay after cardiac surgery remains high. Identification of risk factors will help to reduce the mortality with help of regular follow up. The QOL remains low in all dimensions especially those measuring physical aspects and pain.

Adult↗