Jaime E. Sanchez

The use of silver nylon in preventing surgical site infections following colon and rectal surgery

BACKGROUND: Patients who undergo colorectal surgery have up to a 30% chance of developing a surgical site infection postoperatively. Silverlon is a silver nylon dressing designed to prevent surgical site infections, but only anecdotal evidence has previously supported its efficacy. OBJECTIVE: The aim of this study was to evaluate the effect of silver nylon dressings in patients undergoing colorectal surgery. DESIGN: We performed a prospective, randomized, controlled trial comparing a silver nylon dressing with gauze dressings in patients undergoing elective colorectal surgery. SETTING: The study was performed at a university-based, tertiary referral center. PATIENTS: We studied patients undergoing elective colorectal surgery with an abdominal skin incision of at least 3 cm. INTERVENTION: Patients were randomly assigned to receive either a silver nylon or a gauze dressing. MAIN OUTCOME MEASURES: The primary end point was surgical site infection occurring within 30 days of surgery. RESULTS: One hundred ten patients were enrolled in the study and were randomly assigned to 1 of 2 treatment groups. After a 30-day follow-up period, the incidence of surgical site infection was lower in the silver nylon group compared with the control group (13% vs 33%, P = .011). Twenty-five patients in the study developed superficial surgical site infections, 5 in the silver nylon group and 14 in the control group (P = .021). Two patients in the study group developed deep wound infections compared with 4 in the control group (P = .438). Multivariate analysis revealed that patients in the control group had a 3-fold increase in risk of infection compared with patients in the silver nylon group (P = .013). LIMITATIONS: A limitation of this study is that the members of the surgical team were not blinded to the treatment groups. CONCLUSION: Silver nylon is safe and effective in preventing surgical site infection following colorectal surgery.

Silver-based dressings for the reduction of surgical site infection: Review of current experience and recommendation for future studies

Surgical site infections (SSIs) are the most common hospital acquired infection in surgical patients, occurring in approximately 300,000-500,000 patients a year. SSIs occur across all surgical specialties, but have increased importance in abdominal, colorectal, obstetrical, gynecological, cardiac, vascular, neurological, transplant, and orthopedic procedures where either the inherent risk is elevated or the consequence of an infection would be severe. Current prevention guidelines reduce, but do not completely eliminate, the occurrence of SSIs. We have found the use of silver-nylon wound dressings to significantly reduce the risk SSI associated with colorectal surgery. In this review, we examine the incidence of SSI in high-risk groups, and identify procedures where silver dressings, and other silver products, have been evaluated for the prevention of SSI. Silver-nylon dressings are a useful adjunct in the prevention of SSI in colorectal surgery, neurological surgery, spinal surgery, and certain cardiovascular and orthopedic procedures. Gynecologic, obstetric, breast, transplant, neck, and bariatric procedures, and surgery in obese and diabetic patients, represent other areas where patients are at increased risk of SSI, but in which silver dressings have not been adequately evaluated yet. Recommendation is made for large prospective studies of silver dressings in these populations.

Do silver-based wound dressings reduce pain? A prospective study and review of the literature

Silver-containing dressings are a mainstay in the management of burn injury and acute and chronic wounds. In addition to antimicrobial activity, there is anecdotal evidence that silver dressings may modulate or reduce wound pain. Pain is subjective and difficult to quantify, and most studies of silver-containing dressings evaluate pain as a secondary rather than a primary outcome. Nevertheless, a dressing with a proven ability to reduce pain independent of systemic analgesics would have great utility. In this study, we compared patient-reported pain levels in patients previously randomized to receiving silver-nylon dressings vs. conventional gauze dressings in a study of surgical site infection. Compared to gauze dressings, patients in the silver dressing group reported less pain between postoperative days 0 and 9 (p<0.02). Post hoc analysis of analgesic use did not reach statistical significance between the groups. The study was completed with a literature review of the effect of silver on pain. Silver-based dressings may reduce wound pain by providing an occlusive barrier or by other as-yet undefined mechanisms. The role of silver in pain relief, however, cannot be definitively stated until well-designed prospective randomized studies evaluating pain as a primary endpoint are carried out.

Simultaneous Tracking, 3D Reconstruction and Deforming Point Detection for Stereoscope Guided Surgery

Tissue deformation is one of the major difficulties in the registration of pre-operative and intra-operative data. Vision based techniques have shown the potential to simultaneously track the endoscope and recover a sparse 3D structure of the tissue. However, most of such methods either assume a static environment or require the tissue organ to have a periodic motion such as respiration. To deal with the general tissue deformation, a new framework is proposed in this paper with the ability of simultaneous stereoscope tracking, 3D reconstruction and deforming point detection in the Minimally Invasive Surgery (MIS) environment. First, we adopt a Parallel Tracking and Mapping (PTAM) framework and extend it for the use of stereoscope in MIS. Second, this newly extended framework enables the detection of deforming points without restricted periodic motion model assumptions. Our proposed method has been evaluated on a phantom model, and in vivo experiments demonstrate its capability for accurate tracking in nearly real time speed as well as 3D reconstruction with hundreds of 3D points. Those experiments have shown that our method is robust towards tissue deformation and hence have promising potential for information integration by registration with pre-operative data.

Colorectal natural orifice transluminal endoscopic surgery (NOTES) and transvaginal/transrectal specimen extraction

Advancements in minimally invasive surgery have both revolutionized laparoscopy and set the stage for the advancement of endoscopic surgery to the forefront of modern medicine. Natural orifice transluminal endoscopic surgery (NOTES) has now become a subject of great interest to surgeons worldwide who wish to reduce the morbidity associated with abdominal operations. However, the application of NOTES to colorectal surgery has thus far been limited due to the complex dissection, anastomosis and specimen extraction typically required when operating on the large bowel. For this reason, laparoscopic-assisted natural orifice surgery has been the means by which most surgeons have begun to incorporate natural orifice surgery into their established practices. Transanal endoscopic surgery, transvaginal-assisted laparoscopy and transrectal specimen extraction are all emerging techniques that may be currently employed, in a hybrid manner, with traditionally accepted laparoscopic operations in order to transition toward less invasive surgery and even pure NOTES. To this end, the vagina appears to be the most practical and widely used site of specimen extraction and adjunct access site for laparoscopic hybrid operations. An accompanying video demonstrates the authors’ preferred technique for transvaginal and transrectal specimen extraction.

Efficient Vessel Feature Detection for Endoscopic Image Analysis

Distinctive feature detection is an essential task in computer-assisted minimally invasive surgery (MIS). For special conditions in an MIS imaging environment, such as specular reflections and texture homogeneous areas, the feature points extracted by general feature point detectors are less distinctive and repeatable in MIS images. We observe that abundant blood vessels are available on tissue surfaces and can be extracted as a new set of image features. In this paper, two types of blood vessel features are proposed for endoscopic images: branching points and branching segments. Two novel methods, ridgeness-based circle test and ridgeness-based branching segment detection are presented to extract branching points and branching segments, respectively. Extensive in vivo experiments were conducted to evaluate the performance of the proposed methods and compare them with the state-of-the-art methods. The numerical results verify that, in MIS images, the blood vessel features can produce a large number of points. More importantly, those points are more robust and repeatable than the other types of feature points. In addition, due to the difference in feature types, vessel features can be combined with other general features, which makes them new tools for MIS image analysis. These proposed methods are efficient and the code and datasets are made available to the public.

Validity of the ≥50% Response Threshold in Treatment With NASHA/Dx Injection Therapy for Fecal Incontinence

Objectives:Many fecal incontinence (FI) studies define primary efficacy outcome as a decrease from baseline of ≥50% in the number of FI episodes; this threshold has never been validated. We aimed to establish the validity and responsiveness of ≥50% reduction in FI episodes (responder50) as the threshold indicative of clinically meaningful response.Methods:Adults with a Cleveland Clinic Florida fecal incontinence score ≥10 were randomized to receive nonanimal stabilized hyaluronic acid/dextranomer (NASHA/Dx) injection or sham treatment in a 6-month trial. Validity and responsiveness of the primary end point were evaluated post hoc. The data were compared using different thresholds for defining a responder for a number of end points.Results:Data from 206 patients (NASHA/Dx, n=136; sham, n=70) were evaluated. Incremental patient response threshold increases showed that although the percentage of patients who achieved response decreased with increasing threshold, the difference between treatments remained significant up to an 80% response threshold (NASHA/Dx, 23%; sham, 10%; P=0.02). Response thresholds between 40% and 80% demonstrated evidence for convergent validity, with the strongest correlation with the number of FI episodes, the number of FI episodes when the patient was awake, and the number of FI-free days observed at ≥40% and ≥50% thresholds. Further examination of the responder50 threshold indicated that, regardless of treatment (NASHA/Dx or sham), responders performed significantly better than nonresponders on nearly all secondary efficacy end points.Conclusion:This study demonstrates the responsiveness, validity, and clinical applicability of the ≥50% response threshold in clinical studies of patients with FI receiving treatment with NASHA/Dx.

Vesselness based feature extraction for endoscopic image analysis

Distinctive features are crucial to many tasks in computer assisted minimally invasive surgeries (MIS). Most existing methods are difficult to extract distinctive features in MIS images. For better analysis of MIS images, we resort to blood vessels that are abundant and distinctive on the tissue surfaces. Based on vascular branching points, we propose a new type of vascular feature, branching segment. Two novel methods, Vesselness Based Circle Test (VBCT) and Vesselness based Branching Segment Detection (VBSD) are proposed to detect branching points and branching segments respectively. In the experiments, the performance of VBCT and VBSD is evaluated with in vivo images and VBCT is compared with other state-of-the-art feature point detectors. The numerical results verify that branching points and branching segments are highly repeatable under different viewpoints. Moreover, the computational complexity of VBCT and VBSD is linear to the number of pixels. As supplements to other types of feature point detectors, VBCT and VBSD provide researchers new tools for endoscopic image analysis.

Surgical simulation: the value of individualization

Surgical simulation programs have the potential to broadly benefit numerous healthcare stakeholders. Patients, hospital, and surgeons themselves all stand to gain, either directly or indirectly, from skills that can be learned and refined through simulation. This is especially true in communities with residencies and fellowships where proficiency of surgical technique remains in development for novice surgeons. With public pressure for increased oversight of surgeons in training, prevention of medical errors, reductions in health care costs and decreased work hours, current residents have a much different training experience today than in years past [1–4]. Limited work hours have led to reduced exposure of surgical trainees to operative procedures and the ability to practice those associated technical skills [5]. Bridging this educational gap will become more important than ever as proficiency-based evaluation overtakes the traditional time-based model [6–8]. Many now look to simulation as the possible solution for deficits emerging in current surgical training and as a way to improve patient safety and possibly overall costs. Benefits of simulation

Unobtrusive augmentation of critical hidden structures in laparoscopy.

A fundamental problem in implementing augmented reality (AR) surgery is characterizing how visualizations effect surgeon perception. This problem is important because procedure outcomes depend on surgeon ability to perceive hidden and visible structure interrelation which may be quite dynamic. AR techniques such as x-ray vision are designed to compensate for or reintroduce depth cues lost overlaying hidden structures on a view stream. Such enhancements are necessarily deviations, which may obtrude. This paper provides discussion of hidden structure rendering, analysis, a proposed framework, protocol and experiment (n=2500) for safe evaluation within in vitro laparoscopic video from, and minimal transfer to, in vivo surgery. Results evidence our protocol enables comparison of hidden structure visualizations on task efficacy in vitro and suggest promising new direction towards validating AR in live surgery.