Biomedical subjects

Kenneth T Pace

Publications and source records attributed to Kenneth T Pace.

12 recordsLinked to original sources

PubMed2006

Virtual reality ureteroscopy simulator as a valid tool for assessing endourological skills.

AIM: Virtual reality (VR) simulators are now commercially available for various surgical skills training. The Uro Mentor VR Ureteroscopy Simulator by Symbionix is one system that may revolutionize the way we assess and teach surgical residents. Surgical educators may no longer have to depend on the operating room as the sole venue for teaching residents technical skills. We validated performance on this new system with previously developed assessment tools and compared it to performance on a high fidelity ureteroscopy bench model. METHODS: Urology residents (n = 16) were assessed on their ability to perform cystoscopy, guidewire insertion, semirigid ureteroscopy and basket extraction of a distal ureteric stone on the VR simulator. A blinded examiner assessed subject performance using a checklist, global rating scale and a pass/fail rating. In addition, computer-generated parameters including time to complete task, scope and instrument trauma and the number of attempts to insert a guidewire were analysed. Performance on the VR simulator was compared to performance on a high fidelity ureteroscopy bench model. RESULTS: Senior residents (n = 8) scored significantly higher on their global rating scale (29.4 +/- 2.5 vs 20.8 +/- 0.9, P = 0.005), checklist (19.1 +/- 1.1 vs 15.2 +/- 0.9, P = 0.02), pass/fail rating (chi(2) = 7.3, P = 0.007) and required less time to complete the task (352.9 +/- 55.7 s vs 576.8 +/- 67.4 s., P = 0.02) than the junior residents (n = 8) on the VR simulator. Junior residents also had a significantly higher incidence of scope trauma (4 vs 0.6, P = 0.02). No significant differences were noted in instrument trauma and the number of attempts to insert the guidewire. Global rating scale performance on the VR simulator correlated well to performance on the high fidelity ureteroscopy bench model (r = 0.7, P = 0.002) as did time to complete task (r = 0.7, P = 0.004). CONCLUSIONS: The Uro Mentor VR Ureteroscopy Simulator is a useful tool in assessing resident endourological skills. Performance on the VR simulator is comparable to a validated high fidelity ureteroscopy bench model. Future studies will assess the utility of VR simulators in surgical skills training.

Adult↗

PubMed2006

Status of urologic laparoscopy in 2004: a survey of CUA members.

INTRODUCTION: The optimal method of acquiring laparoscopic skills has not been determined. We sought to examine the current status of urologic laparoscopy and how practicing urologists acquired the skills needed to perform laparoscopic procedures. METHODS: A mail questionnaire regarding laparoscopic practices and training was sent to 480 members of the Canadian Urological Association (CUA) using standard Dillman survey methodology. RESULTS: Three hundred (62.5%) urologists responded to the questionnaire; 56.5% practiced in the community and 41.1% in an academic setting. There were 59.9% who had completed some form of fellowship training. Recent graduates (who finished residency after 1995) were more likely to perform all types of laparoscopic procedures compared to older graduates (65% versus 29.7%, p < 0.001). Advanced procedures were also performed more frequently by recent graduates (52.5% versus 23.4%, p < 0.001). Of those who do not currently perform laparoscopy, 38.2% plan to learn in the future. The most common method of acquiring laparoscopic skills was with animal laboratory experience (39.4%), but only 20.9% relied solely on this method. A trip to a centre of excellence (28.5%) and training from an urologist at the same institution (25.7 %) was also commonly reported as methods of acquiring skills. There were 48.8% who reported beginning laparoscopic procedures without a mentor. CONCLUSIONS: A substantial portion of the Canadian urological community employs laparoscopy, although recent graduates are more likely to do so. Training methods in laparoscopy are variable, but a substantial portion of urologists begin practicing laparoscopic procedures without formal mentoring.

Adult↗

PubMed2005

Semirigid ureteroscopy of the proximal ureter can be aided by external lower-abdominal pressure.

BACKGROUND AND PURPOSE: Smaller semirigid ureteroscopes with large working channels and excellent optics are widely available. Ureteroscopic treatment of upper-ureteral stones has become increasingly popular, although flexible ureteroscopy is more frequently the method of choice. Access to the upper ureter with a semirigid ureteroscope (SR-URS) can be challenging and hazardous, especially when negotiating the iliac vessels. We sought to determine whether lower-abdominal pressure (LAP) facilitated SR-URS access to the upper ureter for safe laser lithotripsy. PATIENTS AND METHODS: Thirty-two consecutive patients who underwent ureteroscopic management of upper- ureteral stones were evaluated. Twenty-four (75%) were male; seventeen (53%) had a right-sided stone. The mean largest stone diameter was 10.2 +/- 4.6 mm. These 32 patients were compared with a matched cohort of patients who underwent SR-URS procedures without the use of LAP. RESULTS: Access to the upper ureter was possible in 30 patients (94%). The LAP was helpful in 18 patients (56%): it facilitated passage of the SR-URS in 16 patients (50%) and laser fiber placement in 11 cases (34%). Access to the upper ureter was possible in all women. The mean operative time was 54 minutes in the LAP group and 75 minutes in the matched cohort without LAP (P = 0.026). There were no significant deformities of the SR-URS and no complications. CONCLUSIONS: Contrary to popular practice, the upper ureter can be accessed safely and efficiently with a 7.5F SR-URS in nearly all patients. Lower-abdominal pressure can be helpful to negotiate passage of the endoscope over the iliac vessels or to place the laser fiber on stones.

Adult↗

PubMed2005

Comparison of Peditrol irrigation device and common methods of irrigation.

BACKGROUND AND PURPOSE: The Peditrol is a novel hands-free irrigation device that delivers a bolus of irrigant through the ureteroscope when the foot pedal is deployed. The purpose of this study was to compare the flow and pressures created by the Peditrol with those of commonly used methods of irrigation. MATERIALS AND METHODS: Flows through a flexible 6.9F Olympus ureteroscope (F-URS) and a 7.5F semirigid ACMI ureteroscope (S-URS) were measured in duplicate with the working channel empty and with a 2.2F Nitinol basket or a laser fiber in the working port. Irrigant flow was pressurized by gravity drainage at 100 cm H(2)O (GI), pressurized irrigant bag at 300 cm H(2)O (PI), handheld 60-cc syringe (HS), and the Peditrol. A 20-gauge angiocatheter was placed through the parenchyma into the renal pelvis of an ex-vivo cadaveric porcine kidney and attached to a pressure transducer. Pressures were measured in triplicate using the same irrigation techniques. RESULTS: With a basket or 200-microm laser fiber in the working port of the F-URS, Peditrol mean flows were superior to those of PI (3.3 and 6.3 times, respectively; P < 0.001) but similar to those of HS (0.7 to 1.1 times). All irrigation types resulted in intrarenal pressures greater than gravity irrigation (P < 0.05). The Peditrol demonstrated intrapelvic pressures <40 cm H(2)O when used with a 12/14F ureteral access sheath (AS). Without an AS, the intrapelvic pressure reached 92 cm H(2)O, similar to the pressures reached with the S-URS under various irrigation conditions (84-287 cm H(2)O) and comparable to the HS method through the F-URS (97 cm H(2)O). CONCLUSIONS: The Peditrol irrigation device generates superior flow through an F-URS compared with GI or PI, particularly with an instrument in the working port. Intrarenal pressures when used with an F-URS and AS are low. When an AS is not used, the intrarenal pressure is similar to or lower than pressures obtained using an S-URS with different irrigation modalities.

Animals↗

PubMed2005

Shock wave lithotripsy at 60 or 120 shocks per minute: a randomized, double-blind trial.

PURPOSE: The rate of shock wave administration is a factor in the per shock efficiency of shock wave lithotripsy (SWL). Experimental evidence suggests that decreasing shock wave frequency from 120 shocks per minute results in improved stone fragmentation. To our knowledge this study is the first to examine the effect of decreased shock wave frequency in patients with renal stones. MATERIALS AND METHODS: Patients with previously untreated radiopaque stones in the renal collecting system were randomized to SWL at 60 or 120 shocks per minute. They were followed at 2 weeks and 3 months. The primary outcome was the success rate, defined as stone-free status or asymptomatic fragments less than 5 mm 3 months after treatment. RESULTS: A total of 220 patients were randomized, including 111 to 60 shocks per minute and 109 to 120 shocks per minute. The 2 groups were comparable in regard to age, sex, body mass index, stent status and initial stone area. The success rate was higher for 60 shocks per minute (75% vs 61%, p = 0.027). Patients with larger stones (stone area 100 mm or greater) experienced a greater benefit with treatment at 60 shocks per minute. The success rate was 71% for 60 shocks per minute vs 32% (p = 0.002) and the stone-free rate was 60% vs 28% (p = 0.015). Repeat SWL was required in 32% of patients treated with 120 shocks per minute vs 18% (p = 0.018). Fewer shocks were required with 60 shocks per minute (2,423 vs 2,906, p <0.001) but treatment time was longer (40.6 vs 24.2 minutes, p <0.001). There was a trend toward fewer complications with 60 shocks per minute (p = 0.079). CONCLUSIONS: SWL treatment at 60 shocks per minute yields better outcomes than at 120 shocks per minute, particularly for stones 100 mm or greater, without any increase in morbidity and with an acceptable increase in treatment time.

Adult↗

PubMed2003

Erect and supine radiographs to assess effectiveness of SWL for stones in a caliceal diverticulum or dilated calix.

BACKGROUND AND PURPOSE: There are patients who have been treated with shockwave lithotripsy (SWL) for stones in a caliceal diverticulum (CD) or a dilated calix in whom the degree of fragmentation is difficult to assess. The aim of this study was to see if adequate fragmentation could be confirmed by the demonstration of layering of fine fragments on an erect radiograph. PATIENTS AND METHODS: Over a period of 9 months, 13 patients with stones in a CD or a dilated calix with a stenosed infundibulum were studied 2 weeks after SWL with erect and supine radiographs. RESULTS: One of eight patients with a CD cleared all fragments. Two patients showed no change in the appearance of the stone on either the supine or the erect film, and of the remaining five patients, three demonstrated layering of sand at the base of the CD. Five patients with a dilated calix and a narrow infundibulum were also studied: two of these patients became stone free, two demonstrated complete fragmentation with layering of the sand, and in one patient, a 4-mm fragment, hidden within the sand, was revealed only on the erect film. CONCLUSION: There are patients who have been treated with SWL for stones in a CD or a dilated calix in whom adequate fragmentation is difficult to demonstrate. An erect radiograph in these patients may demonstrate layering of the fragments to confirm fragmentation and obviate repeat SWL.

Dilatation, Pathologic↗

PubMed2003

Removal of asymptomatic ipsilateral renal stones following rigid ureteroscopy for ureteral stones.

PURPOSE: To evaluate the feasibility and outcome of flexible ureteroscopic removal of small (<1-cm) asymptomatic renal stone(s) following rigid ureteroscopy for ureteral stones. PATIENTS AND METHODS: Ten female and nineteen male patients underwent rigid ureteroscopy and holmium lasertripsy for removal of ureteral stone(s). All had asymptomatic renal stone(s) on the same side, which were then removed using flexible ureteroscopy. The renal stones were either removed intact with a tipless Nitinol basket or fragmented with the laser to small pieces (<2 mm), with basket removal of larger fragments. The number and size of stones, total operative time, added time needed for flexible ureteroscopy, and intraoperative and postoperative complications were recorded. Follow-up at 1 month included a plain abdominal film and renal ultrasonography or noncontrast CT scan. RESULTS: Fifty-six renal stones with a mean size of 5.7 mm were treated. Fourteen patients had stones on the right side, and 15 had stones on the left. The mean total operative time was 56.5 minutes, with a mean added time of 16.7 minutes for flexible ureteroscopy. Stones were removed intact in 18 patients and fragmented in 8 patients, resulting in an immediate success rate of 90%. There were three failures. One-month follow-up confirmed all patients were either stone-free or had residual fragments <2 mm in diameter, with no new-onset hydronephrosis. CONCLUSIONS: Removal of small asymptomatic renal stones at the time of ureteroscopy for ureteral stones appears safe and effective and requires little additional operative time.

Female↗

PubMed2003

Randomized, single-blind comparison of sidehole and end-hole v end-hole ureteral catheters.

BACKGROUND AND PURPOSE: Flexible 5F, open-ended ureteral catheters are currently available only with an end hole, which can lead to difficulties during retrograde pyelography and when aspirating urine for culture or cytology, as the hole frequently sucks up urothelium or debris and becomes occluded. We compared the traditional end-hole ureteral catheter with a catheter having a sidehole as well. PATIENTS AND METHODS: Twenty-two patients requiring aspiration of urine from the renal pelvis for cytology study or culture or to empty the collecting system during retrograde pyelography or prior to percutaneous nephrolithotomy were enrolled. Both end-hole-only and end-hole + sidehole catheters were employed in each patient, but the order of use was randomized, and the endourologist was blinded to the catheter type. Catheters were placed in the renal pelvis under fluoroscopy, and the renal collecting system was filled with 5 mL of contrast medium. The catheters were compared on volume aspirated initially, volume aspirated after repositioning, and ease of use judged on a three-item adjectival scale. RESULTS: The end-hole + sidehole catheters were able to aspirate more fluid initially (5.1 mL v 2.6 mL; P < 0.001) and after repositioning (6.0 mL v 3.4 mL; P < 0.001). In addition, blinded urologists rated these catheters easier to use (12.0 v 3.0; maximum score 15; P < 0.001). CONCLUSIONS: The addition of a sidehole to ureteral catheters offers significant advantages to the endourologist seeking to aspirate urine from the upper collecting system for culture or cytology or during retrograde pyelography and in preparation for stone removal. The sidehole prevents occlusion of the catheter when it sucks up the urothelium and provides more efficient drainage of the upper tract.

Catheterization↗

PubMed2003

Laparoscopic adrenalectomy: pathologic features determine outcome.

INTRODUCTION: The differential outcomes of laparoscopic adrenalectomy are not well described. Therefore, we evaluated these outcomes in the 3 groups most often seen clinically: bilateral adrenalectomy for Cushing's disease (group 1), pheochromocytoma (group 2) and unilateral adrenalectomy for non-pheochromocytoma (group 3). METHODS: We reviewed a longitudinal database of 72 consecutive cases of laparoscopic adrenalectomy carried out between 1997 and 2001 at the Centre for Minimally Invasive Surgery, University of Toronto. RESULTS: Patients in group 1 tended to be older (median 49 yr) and heavier (median 87 kg). They had a longer operating time (median 255 min), more postoperative complications (15%) and a longer median postoperative stay (4 d). Patients in group 2 had intermediate outcomes: a median operating time of 198 minutes, complication rate of 8.3% and a median postoperative hospital stay of 3 days. However, they had more intraoperative blood loss (median 150 mL). Group 3 patients had the best outcomes with the shortest median operating time (125 min), least blood loss (median 50 mL), fewer complications (6%) and shortest hospital stay (median 2 d). CONCLUSIONS: Although the outcomes of laparoscopic adrenalectomy are uniformly good, on the basis of the underlying pathologic characteristics, patients can be divided into groups that have different expected outcomes. Patients requiring a unilateral adrenalectomy except for pheochromocytoma have the best recorded outcomes. Surgeons transferring to laparoscopic adrenalectomy would benefit from selecting patients in this group during their learning curve.

Adenoma↗

PubMed2002

Munchausen syndrome presenting as gross hematuria in two women.

Munchausen syndrome is an uncommon disorder in which patients present with fictitious disorders and a self-destructive urge to undergo invasive procedures. We present 2 cases of nurses who presented with recurrent urinary tract infections, flank pain, and gross hematuria. One patient had such severe hematuria as to require transfusions of more than 1000 U of packed red cells during a 30-year period. Both patients underwent extensive investigations--all of which were normal. One patient even underwent nephrectomy, which showed normal pathologic findings. Both were found to be phlebotomizing themselves and infusing blood into their bladders.

Adult↗

PubMed2002

Unique methodological issues facing randomized controlled trials of endourologic procedures.

Randomized controlled trials provide the optimal design for evaluating the effectiveness of treatment but have not been widely accepted by surgical investigators. Although there are several methodological and ethical difficulties, none is insurmountable. In the United Kingdom, a regulatory agency has been established to supervise the introduction of new medical procedures, and something similar might be seen in the United States, particularly given the pressure from the government and third-party payors for proof of efficacy and cost effectiveness. Endourologists have responded to similar challenges in the past and must continue to do so.

Cost-Benefit Analysis↗

PubMed2002

Laparoscopic v open donor nephrectomy: a cost-utility analysis of the initial experience at a tertiary-care center.

BACKGROUND AND PURPOSE: Laparoscopic donor nephrectomy (LapDN) offers donors more rapid postoperative recovery and recipients equivalent graft function when compared with open donor nephrectomy (OpenDN). Nonetheless, costs are less favorable for LapDN than for OpenDN. We compared LapDN and OpenDN with cost-utility analysis. METHODS: A decision analysis modeling approach was performed: utilities derived using time trade-off and quality-adjusted life year (QALY) techniques; probabilities derived from a systematic review of the literature. All costs were included from a societal perspective using actual cost data from OpenDN and LapDN patients performed contemporaneously between July 1, 2000 and December 31, 2000. Costs of lost employment were estimated using mean provincial annual earnings. Incremental cost-effectiveness ratio (ICER) was calculated with "best-case" and "worst-case" scenarios for confidence intervals; sensitivity analyses were used to assess robustness. RESULTS: LapDN costs are higher ($10,317.40 vs. $9,853.70), while quality of life (QOL) is superior (0.7683 vs. 0.7062). The ICER from a societal perspective was C$7,471.11/QALY. If all donor nephrectomies nationally were performed laparoscopically, there would be an additional annual cost of C$665,240 with a societal gain of 24.84 QALYs. CONCLUSIONS: LapDN offers improved QOL at marginally higher cost. A societal ICER of $7,471.11/QALY compares favorably to many accepted health-care interventions. By potentially increasing organ donor rates, LapDN may be cost saving by decreasing the number of patients on dialysis.

Aftercare↗