Note: pneumatically modulated liquid delivery with feedback control.

We present the design and characterization of a pneumatically driven liquid delivery system using an embedded microcontroller with feedback control capable of maintaining a stable, constant flow rate over several hours of operation. Flow rates with relative standard deviations less than 1% were achieved and compared to a typical laboratory syringe pump.

Advanced glycation end products accumulate in the reproductive tract of men with diabetes.

Light microscopic studies comparing sperm parameters show little association between diabetes and male fertility. However, with the introduction of new analytical techniques, evidence is now emerging of previously undetectable effects of diabetes on sperm function. Specifically, a recent study has found a significantly higher sperm nuclear DNA fragmentation in diabetic men. As advanced glycation end products (AGEs) are important instigators of oxidative stress and cell dysfunction in numerous diabetic complications, we hypothesized that these compounds could also be present in the male reproductive tract. The presence and localization of the most prominent AGE, carboxymethyl-lysine (CML), in the human testis, epididymis and sperm was determined by immunohistochemistry. Parallel ELISA and Western blot analyses were performed to ascertain the amount of CML in seminal plasma and sperm from 13 diabetic and nine non-diabetic subjects. CML immunoreactivity was found throughout the seminiferous epithelium, the nuclei of spermatogonia and spermatocytes, in the basal and principle cells cytoplasm and nuclei of the caput epididymis and on most sperm tails, mid pieces and all cytoplasmic droplets. The acrosomal cap, especially the equatorial band, was prominently stained in diabetic samples only. The amount of CML was significantly higher (p = 0.004) in sperm from non-diabetic men. Considering the known detrimental actions of AGEs in other organs, the presence, location and quantity of CML, particularly the increased expression found in diabetic men, suggest that these compounds may play a hitherto unrecognized role in male infertility.

Insulin dependant diabetes mellitus: implications for male reproductive function.

BACKGROUND: Diabetes mellitus (DM) is increasing in men of reproductive age. Despite this, the prevalence of diabetes in men attending fertility clinics is largely unknown. Furthermore, studies examining the effects of DM on sperm fertility potential have been limited to conventional semen analysis. METHODS: Conventional semen analysis (semen volume, sperm count, motility and morphology) was performed for 27 diabetic (mean age 34+/-2 years) and 29 non-diabetic subjects (control group, men undergoing routine infertility investigations, mean age 33+/-1 years). Nuclear DNA (nDNA) fragmentation was assessed using the alkaline Comet assay and mitochondrial DNA (mtDNA) deletions by Long-PCR. RESULTS: Other than a small, but significant, reduction in semen volume in diabetic men (2.6 versus 3.3 ml; P<0.05), conventional semen parameters did not differ significantly from control subjects. Diabetic subjects had significantly higher mean nDNA fragmentation (53 versus 32%; P<0.0001) and median number of mtDNA deletions (4 versus 3; P<0.05) compared with control subjects. CONCLUSIONS: Diabetes is associated with increased sperm nuclear and mtDNA damage that may impair the reproductive capability of these men.

Improving continuing medical education for surgical techniques: applying the lessons learned in the first decade of minimal access surgery.

OBJECTIVE: To examine the first decade of experience with minimal access surgery, with particular attention to issues of training surgeons already in practice, and to provide a set of recommendations to improve technical training for surgeons in practice. SUMMARY BACKGROUND DATA: Concerns about the adequacy of training in new techniques for practicing surgeons began almost immediately after the introduction of laparoscopic cholecystectomy. The concern was restated throughout the following decade with seemingly little progress in addressing it. METHODS: A preliminary search of the medical literature revealed no systematic review of continuing medical education for technical skills. The search was broadened to include educational, medical, and psychological databases in four general areas: surgical training curricula, continuing medical education, learning curve, and general motor skills theory. RESULTS: The introduction and the evolution of minimal access surgery have helped to focus attention on technical skills training. The experience in the first decade has provided evidence that surgical skills training shares many characteristics with general motor skills training, thus suggesting several ways of improving continuing medical education in technical skills. CONCLUSIONS: The educational effectiveness of the short-course type of continuing medical education currently offered for training in new surgical techniques should be established, or this type of training should be abandoned. At present, short courses offer a means of introducing technical innovation, and so recommendations for improving the educational effectiveness of the short-course format are offered. These recommendations are followed by suggestions for research.

The impact of external feedback on computer-assisted learning for surgical technical skill training.

BACKGROUND: Computer-assisted learning (CAL) offers a number of potential advantages for surgical technical skills teaching. The purpose of this study was to evaluate the impact of individualized external feedback on surgical skill acquisition when a CAL package is used for instruction. METHODS: Freshman and sophomore students participated in a 1-hour CAL session designed to teach them how to tie a two-handed square knot. One group received individualized external feedback during the session and the other group did not. Subjects were videotaped performing the skill before and after the session. The tapes were independently analyzed, in blinded fashion, by three surgeons. Three measures were obtained: the total time for the task, whether or not the knot was square, and the general quality of the performance using a rating scale. RESULTS: Data from 105 subjects were available for final analysis. For both groups there were significant increases in the proportion of knots that were square when the posttest performance was compared with the pretest performance but there was no difference between groups on this measure. Comparison of the performance scores demonstrated that both groups had a significant improvement after the session but the performance scores were significantly better in the group that had received feedback. CONCLUSIONS: Novices in both groups using CAL showed improvement in two of the outcomes measured, suggesting that subjects in both groups attained some degree of competence with this skill. The higher posttest performance score for the group receiving feedback demonstrates that external feedback results in a higher level of mastery when CAL is used to teach surgical technical skills.

Peer teaching and computer-assisted learning: An effective combination for surgical skill training?

BACKGROUND: The surgical literature suggests that collaborative learning using peers may be a valid way to teach surgical skills and there is a growing interest in the use of computer-assisted learning for this purpose. Combining this evolving technology with this type of teaching would theoretically offer a number of advantages including a reduction in the amount of faculty time devoted to this task. In this study, we evaluate the efficacy of a type of collaborative learning in a computer-assisted learning environment. MATERIALS AND METHODS: We designed a prospective, randomized study comparing novice learners who were allowed to work in pairs with those who worked independently in a specially equipped computer-assisted learning classroom. Both pretest and posttest assessments were performed by videotaping this skill. Three experts then evaluated the videotapes, in a blinded fashion. Three different outcomes were assessed. RESULTS: Seventy-seven subjects were enrolled in and completed the study. Comparison of the outcome measures demonstrated no between group difference in the average performance scores or posttest times. The proportion of subjects who correctly tied a square knot was significantly lower in the computer-assisted peer teaching group when compared with the computer-assisted learning alone group (P = 0.04). CONCLUSIONS: Collaborative learning in a computer-assisted learning environment is not an effective combination for teaching surgical skills to novices.

A virtual reality module for intravenous catheter placement.

BACKGROUND: Virtual reality (VR) is a potential tool for technical skills training. We tested the validity and instructional effectiveness of a prototype VR module for learning intravenous (i.v.) catheter placement. METHODS: First-year medical students (n = 37), third-year medical students (n = 14), and surgical residents (n = 9) attempted two pretest i.v.s into each other, used the VR module for 12 minutes, and subsequently attempted two posttest i.v.s. Success or failure were recorded for each attempt. For each successful attempt, time and global rating of i.v. insertion were also recorded. RESULTS: The pretest success rate was significantly different between groups (chi square = 28.71, P <0.01). VR success rate was not significantly different between groups (F(2,57) = 1.47, ns). Although there was improvement in all groups during VR training (F(2,114) = 44.16, P <0.01), this did not result in improvement in posttest performance. CONCLUSIONS: Significant differences between groups were observed in performance of i.v. insertion in physical reality. However, no significant difference was observed in performance in VR. Thus, performance in VR demonstrated neither construct nor concurrent validity. While performance improved in VR, transfer of skill from VR to physical reality was not observed. Additional development and testing of VR as a training tool is warranted before its widespread use can be recommended.

Enrolment procedures and self-selection by patients: evidence from a Polish family practice.

This paper examines the consequences of patient enrollment procedures in a capitation-based family practice in Krakow (Poland), where the local city government used two different methods for preparation of patient lists. In the first, the city gave the individuals living within the practice area the option of withdrawing from being enrolled in the practice; in the second, individuals were given the option of enrolling in the practice. These two enrollment procedures, identified as 'active-negative' and 'active-positive' respectively, provide a natural experiment for investigating the effects of an enrollment methodology on the economics of a physician's practice. An examination of the data indicates that self-selecting enrollees utilize significantly greater quantities of health care compared to others, and university educated individuals and individuals more likely to fall ill are more likely to self-select into a practice. The study suggests that in order to reduce demand-side adverse selection, either the system of active-positive enrollment should be modified, or capitation rates should be risk-adjusted by health status rather than by demographic variables only. The policy implications of this study become even more significant as more and more physicians leave their salaried jobs to start state-financed independent practices.

Neonatal pharyngeal pseudodiverticulum mimicking esophageal atresia.

Pseudodiverticulum of the hypopharynx is an infrequent but potentially serious complication of orogastric or nasogastric tube insertion and endotracheal intubation. We report two cases of injury to the hypopharynx resulting in a pseudodiverticulum of the hypopharynx that was initially diagnosed as esophageal atresia. Both cases were managed successfully by conservative therapy. We also review the literature regarding neonatal pharyngeal pseudodiverticulum.

Computer-assisted learning versus a lecture and feedback seminar for teaching a basic surgical technical skill.

BACKGROUND: Rapid improvements in computer technology allow us to consider the use of computer-assisted learning (CAL) for teaching technical skills in surgical training. The objective of this study was to compare in a prospective, randomized fashion, CAL with a lecture and feedback seminar (LFS) for the purpose of teaching a basic surgical skill. METHODS: Freshman medical students were randomly assigned to spend 1 hour in either a CAL or LFS session. Both sessions were designed to teach them to tie a two-handed square knot. Students in both groups were given knot tying boards and those in the CAL group were asked to interact with the CAL program. Students in the LFS group were given a slide presentation and were given individualized feedback as they practiced this skill. At the end of the session the students were videotaped tying two complete knots. The tapes were independently analyzed, in a blinded fashion, by three surgeons. The total time for the task was recorded, the knots were evaluated for squareness, and each subject was scored for the quality of performance. RESULTS: Data from 82 subjects were available for the final analysis. Comparison of the two groups demonstrated no significant difference between the proportion of subjects who were able to tie a square knot. There was no difference between the average time required to perform the task. The CAL group had significantly lower quality of performance (t = 5.37, P <0.0001). CONCLUSIONS: CAL and LFS were equally effective in conveying the cognitive information associated with this skill. However, the significantly lower performance score demonstrates that the students in the CAL group did not attain a proficiency in this skill equal to the students in the LFS group. Comments by the students suggest that the lack of feedback in this model of CAL was the significant difference between these two educational methods.

A prospective, randomized comparison of traditional and laparoscopic inguinal exploration in children.

The indications for routine exploration of the asymptomatic contralateral groin during pediatric herniorrhaphy remain controversial. Laparoscopy through the open hernia sac has been described as an alternative to this traditional approach and appears to offer some advantages. In deciding whether this technique should be introduced into our clinical practice, we sought to discover whether there was a significant time difference between these two methods and if there were unique complications associated with this approach. We elected to answer this question in a prospective, randomized study. A total of 18 patients completed the study. There were no significant complications in either group. The average total surgical procedure time in the laparoscopy group was 47.5 minutes versus 41 minutes in the traditional group, which is not a statistically significant difference. We conclude from this prospective, randomized pilot study that laparoscopic exploration can be introduced into a pediatric surgical practice without a significant time penalty, and we currently offer it as a reasonable and safe alternative to our patients.

Combined sequestration, bronchogenic cyst, and dysgenetic lung simulating congenital lobar emphysema.

We report the case of a newborn with bronchopulmonary sequestration, bronchogenic cyst, and dysgenetic lung that radiographically simulated congenital lobar emphysema. We discuss congenital malformations of the lungs and the concept of a continuum in the development of pulmonary anomalies.

The status of pediatric surgical rotations by residents in pediatrics.

A variety of forces are reshaping the traditional relationship between physicians and their patients. One consequence of this reform movement will be increased responsibility of the pediatrician to evaluate children with surgical diseases. Pediatricians also will be encouraged to do more of the minor surgical procedures themselves. It is not clear how academic pediatric surgeons should adapt to these changes to assure that the general pediatrician is equipped with the skills to handle this increased responsibility. One obvious solution would be to have the pediatrician in training rotate on the pediatric surgery service. The authors have considered these issues at their institution, and thus became interested in learning the status of pediatric surgical rotations by pediatric house staff in this country. A survey was distributed to the 221 accredited pediatric training programs in this country, and 143 individuals responded. Only thirty-five of these programs require a rotation on pediatric surgery. Eighty-six programs offer it as an elective, but only a minority of house staff takes it. The most disturbing aspect of the survey was the 28 of the programs had required a pediatric surgical rotation in the past but had eliminated it. The most common reasons given for this action were the poor educational content of the rotation and the labor requirements of the pediatric service. Based on the survey, the authors believe that it is unlikely that mandatory rotations on pediatric surgery will be begun in pediatric training curriculums. If pediatric surgeons wish to be involved in training pediatricians, they will need to address the educational content of their electives to meet the changing educational needs of the pediatricians.

A prospective evaluation of an endoscopic ultrasonic probe to detect intraparenchymal malignancy at pediatric thoracoscopy.

Thoracoscopy has been proposed as the procedure of choice for the evaluation of focal, suspected malignant pulmonary lesions in children. One drawback with this approach, however, is the concern that intraparenchymal lesions may go undetected. We prospectively evaluated the ability of an endoscopic ultrasonic probe to detect intraparenchymal nodules. The handheld probe contains a piezoelectric ultrasound emitter and receiver that operates at 7.5 MHz. The axial resolution of the probe is 1.1 cm. Two different probe tips were used. One is a forward viewing tip and the other is angled at 45 degrees relative to the axis of the probe shaft. Both probes image 90 degrees sectors. Twelve thoracoscopies on nine patients were performed using the ultrasound probe. Of seven patients with confirmed metastatic disease, six had thoracoscopy converted to open thoracotomy to assure that no lesion had been missed. The probe was able to accurately assess surrounding bronchovascular structures and the presence and location of previously placed surgical clips. Although deep structures were readily visualized with the probe, lesions within 1.5 cm of the surface of the lung were poorly visualized. No complications occurred. This ultrasound system allows for the distinction of dense lesions from the surrounding pulmonary parenchyma except for those lying near the surface of the lung, which are usually easy to see directly. Furthermore, the images define the broncho vascular structures adjacent to the lesion. This device may enhance thoracoscopy by facilitating the detection of, and ability to resect, pulmonary intraparenchymal lesions.

A comparison of laparoscopic and traditional open splenectomy in childhood.

This study aimed to determine whether laparoscopic splenectomy is more advantageous than open splenectomy in pediatric patients. Data from 61 patients treated between June 1983 and September 1994 were reviewed. Length of hospitalization, hospital costs, operating time, and postoperative complications were evaluated. Forty-seven patients had open splenectomy. Nineteen of these underwent concomitant procedures. Fourteen patients had laparoscopic splenectomy, and four had concomitant cholecystectomy. The data show a trend toward a 1-day reduction in hospital stay associated with laparoscopic splenectomy (P < .02). Operating time was 83% longer for the laparoscopic approach (P < .001), and operating costs were almost $3,000 more (P < .001) than for open splenectomy. The total hospital cost also was greater for laparoscopic procedures (P < .1), primarily reflective of a more than $3,000 difference for splenectomy alone (P < .02). Two of the fourteen laparoscopic patients (14%) had complications. One patient with Evan's syndrome had pneumonia that required antibiotics. Another patient required conversion to an open procedure because of poorly controlled hemorrhage from a short gastric vessel. Twelve of the open splenectomy patients (25%) had complications: atelectasis (3), fever (4), wound infection (2), pneumonia (1), laryngospasm (1), and pancreatitis (1). The authors conclude that laparoscopic splenectomy is a safe but currently more expensive alternative to open splenectomy, primarily because of the use of disposable instruments. Benefits include a shorter hospital stay, no greater risk of postoperative complications, and subjective improvement in the cosmetic result. Disadvantages include increased operating time and cost. Evaluation of larger series will be needed to determine the significance of the difference in complication rates between the two procedures.

Indications for hemiscrotectomy in the management of genitourinary tumors in children.

In the last 30 years at St Jude Children's Research Hospital, 10 boys have undergone hemiscrotectomy for primary testicular tumors or paratesticular rhabdomyosarcoma. Indications for this procedure were scrotal contamination and positive or uncertain surgical margins. Residual tumor was found in only one specimen. There were four complications in the study group. Two patients had complications directly attributable to the hemiscrotectomy, and in one patient this caused a delay in treatment. Preoperative imaging was performed in three patients. This has not been helpful in evaluating residual masses and is not indicated. Based on the authors' experience and a review of the literature, there are a number of indications for hemiscrotectomy in the management of genitourinary tumors in children. Controversies regarding some of these indications should be discussed with the families of these patients during preoperative counseling.

Laparoscopic splenectomy in childhood.

The authors describe their technique for laparoscopic splenectomy in childhood. Five ports, including one 12-mm port for an endoscopic stapler, are placed. With the patient in the supine position, the short gastric vessels are divided between clips. The patient is then placed in the lateral decubitus position for mobilization of the splenic flexure of the colon, division of the posterolateral ligamentous attachments, and en masse transection of the splenic hilum using the EndoGIA stapler. The freed spleen is placed in a nylon reinforced Lap Sac, which is exteriorized at the neck. The spleen is morcellated and the sac removed. Concomitant cholecystectomy is performed in patients with hereditary spherocytosis who have cholelithiasis or sludge. The procedure has been performed without complication in six patients who had hematologic disorders. For another patient, the procedure was converted to an open splenectomy to achieve better hemostasis.

Primary malignancy of the salivary gland in children.

Seventeen pediatric patients with a major salivary gland malignancy (16 parotid, 1 submaxillary) were reviewed. Eight patients presented with carcinoma. The usual presentation was a mass over the affected gland. Six patients had localized disease, which was treated by excision. This was accomplished by either a total or subtotal parotidectomy or resection of the submaxillary gland. Two patients received adjuvant radiation therapy. All six patients with localized carcinoma are alive, without evidence of disease. Two patients presented with metastatic disease and died of the disease despite treatment with multiagent chemotherapy, and in one case, radiation therapy. Nine patients had rhabdomyosarcoma (RMS). The usual presentation was a mass at the angle of the mandible. Five patients had involvement of one or more cranial nerves, and two had concomitant cervical adenopathy. Eight patients had a biopsy and then were treated according to an existing prospective institutional protocol. The ninth patient initially underwent a superficial parotidectomy. Seven patients received radiation therapy. In one patient, rapid progression of the disease precluded this treatment. Seven patients died of progressive local and distant disease 2 months to 2 years (median, 6 months) from the time of diagnosis. Two patients are alive, without evidence of disease, 3 and 7 years after presentation. We conclude that carcinoma should be managed with complete excision. For RMS of the salivary gland, a biopsy should be performed, and treatment should consist of chemotherapy and radiation therapy.

Breast malignancy in children.

In 25 years, 18 patients with breast cancer were treated at St Jude Children's Research Hospital, 16 were female and 2 were male. The patients presented with primary malignancy (2), metastatic disease (13), or secondary malignancy (3). One of the females with primary breast malignancy had alveolar rhabdomyosarcoma. She was treated with wide excision and is currently receiving chemotherapy. The other patient presented with non-Hodgkin's lymphoma of the right breast. After biopsy, she was treated with chemotherapy. Of 13 patients with metastatic disease, the primary lesion was rhabdomyosarcoma in nine. One patient each had non-Hodgkin's lymphoma, Hodgkin's lymphoma, neuroblastoma, and signet-cell adenocarcinoma. All patients with metastatic disease to the breast died of the disease. Three females presented with invasive ductal carcinoma of the breast after treatment for Hodgkin's disease. Two underwent mastectomy and are alive without evidence of disease. One patient refused therapy and died of the second malignancy. We conclude that (1) breast malignancies had three distinctly different presentations in our patients, (2) the breasts of pediatric oncology patients should be carefully and routinely examined for metastatic disease, and (3) metastatic disease in the breast of a child is a manifestation of disseminated disease and is associated with an extremely poor prognosis.

A "smart needle" to facilitate difficult vascular access in pediatric patients.

A new Doppler probe inside a needle was evaluated in a group of infants and children to assess its suitability for subclavian venous access. While the efficient use of this device required learning a new technique, we found the device useful to accurately locate the subclavian vein and differentiate it from the artery in all patients weighing more than 3 kg. This device will be most helpful in cases of difficult access, eg, scar from previous access, obesity, or edema.