Robert A. Underwood

Assessment of fatigue, monitor placement, and surgical experience during simulated laparoscopic surgery

BackgroundLaparoscopic surgery requires the surgeon to assume atypical postures for extended periods of time, potentially leading to fatigue and chronic injury. This study assessed the level of muscle activity and compared the effects of fatigue, monitor placement, and surgical experience during simulated laparoscopic surgery.MethodsFour attending and four resident surgeons repeated a series of four tasks with a Viewsite and a standard operating room monitor. Electromyography (EMG) activity and muscular discomfort scores were obtained before and after a “fatigue session.” Two variables, the EMG amplitudes and discomfort scores, were analyzed.ResultsThe EMG amplitudes generally exceed the recommended threshold limits of acceptable muscular load. EMG data and discomfort scores demonstrated a fatigue response in several muscle groups. Minimal differences between the two monitor positions were seen. Overall, the EMG data and discomfort scores showed less muscle activity and discomfort in the attending surgeons.ConclusionLaparoscopic surgery required a relatively high muscular load, putting surgeons at risk for fatigue and injury. Altering the monitor placement did not reduce the surgeon’s risk of fatigue. Experience slightly reduced the level of fatigue, but not enough to reduce the surgeon’s risk category.

Laparoscopic splenopexy for wandering (pelvic) spleen

Wandering spleen is a rare clinical diagnosis with a high incidence of splenic torsion and infarction. The preferred treatment for this condition currently is splenopexy to reposition and fixate the spleen in the left upper quadrant of the abdomen to preserve splenic function. We recently performed the first splenopexy for a wandering spleen using laparoscopic techniques. The patient was a 19-year-old woman who had an asymptomatic lower abdominal/pelvic mass found on physical examination. Diagnostic evaluation (ultrasound, computed tomography scan, and liver-spleen scan) showed an absent spleen in the upper abdomen, normal uterus and ovaries, and an 11 x 7-cm pelvic spleen. Laparoscopic splenopexy was performed using Vicryl mesh to suspend and fixate the spleen in the left upper quadrant of the abdomen. Total operative time was 175 min, there were no intra- or postoperative complications, and the patient was discharged on the 1st postoperative day. Follow-up at 2 and 7 months indicated that she was asymptomatic with a nonpalpable spleen. The results suggest that a laparoscopic approach to splenopexy should be considered for the treatment of patients with a wandering spleen.

Sodium hyaluronate carboxymethylcellulose-based bioresorbable membrane (seprafilm™)—Does it affect tumor implantation at abdominal wound sites?

PURPOSE: This study examines the effects of a sodium hyaluronate-based bioresorbable membrane (Seprafilm™) on tumor implantation at surgical wound and laparoscopic trocar sites. METHODS: GW-39, an established human colon cancer line carried in immunocompetent golden Syrian hamsters was used as the experimental model. Under general anesthesia, a 2-cm midline incision was made to allow placement of four 5-mm abdominal trocars. Hamsters were then randomly assigned to preSeprafilm™, postSeprafilm™, and control (no Seprafilm™) groups. In the preSeprafilm™ group 0.5 ml of a 5 percent (vol/vol) suspension of the GW-39 tumor cells (∼1.675 × 106 cells) was injected into the abdomen of each hamstervia midline incision. Trocars were removed, the wounds were closed, and 1 cm2 of Seprafilm™ was placed on the peritoneal surface of each trocar site. In the postSeprafilm™ group the membrane was placed at each site before injection of tumor cells. The control group did not receive Seprafilm™. The animals were killed after seven weeks, and the abdominal wound sites were excised. Sites without gross tumor underwent histologic evaluation. RESULTS: One hundred thirty-two animals were randomly assigned to the three groups. The preSeprafilm™ group had an 87 percent tumor implantation rate. The postSeprafilm™ group had a 90 percent tumor implantation rate. The control group had an 88 percent tumor implantation rate. Chi squared analysis demonstrated that these total tumor implant rates and mean tumor mass were similar at all wound sites and between groups. No toxicity was observed in any of the experimental groups. CONCLUSIONS: Sodium hyaluronate-based bioresorbable membrane (Seprafilm™) does not influence GW-39 human colon cancer implantation at abdominal wound sites in this hamster model.

Pneumoperitoneum does not influence trocar site implantation during tumor manipulation in a solid tumor model.

BackgroundThe purpose of this study was to assess tumor implantation at abdominal wound sites following manipulation of a solid abdominal tumor.MethodsGW-39 human colon cancer cells were injected into the omentum of golden Syrian hamsters. At 2 weeks, an omental tumor was harvested and animals were randomized to bivalve (A), crush (B), strip (C), or excision (D), with or without pneumoperitoneum. Four 5-mm trocars were inserted into the abdomen, and the tumor was reinserted through the midline, swept through four quadrants, and removed. The incision was closed and pneumoperitoneum at 7 mmHg was maintained for 10 min. Tumor implantation at wound sites was documented at 7 weeks.ResultsImplantation at trocar sites was 53 and 49% with and without pneumoperitoneum in the manipulated groups (A, B, C), respectively (p = 0.993). Implantation at trocar sites was reduced in the control group (D) at 9 and 10% with and without pneumoperitoneum, respectively (p < 0.001).ConclusionsTumor implantation at trocar sites is due to spillage of tumor during manipulation and not to pneumoperitoneum.

Development of a laparoscopic approach to neurolytic celiac plexus block in a porcine model

AbstractBackground: Neurolytic celiac plexus block (NCPB) is an effective method of palliative pain control in cases of inoperable pancreatic cancer. This study was undertaken to evaluate the feasibility of a laparoscopic approach to NCPB in an experimental animal model. Methods: The laparoscopic technique for NCPB was developed in an acute study of six domestic swine followed by a chronic study of nine domestic swine that were monitored 3–21 days after surgery for adverse neurologic, gastrointestinal, or other sequelae. Using a four-port laparoscopic technique, the esophageal hiatus was dissected to expose the aorta at the level of the diaphragmatic crura. Under combined endoscopic and laparoscopic ultrasound (LUS) guidance, 5 ml of sclerosant dye (95% ethanol mixed with India ink) was injected into either side of the para-aortic soft tissue via a percutaneously placed 18-gauge spinal needle. After the animals were killed, the aorta and periaortic tissue were harvested from each animal for gross and histologic analysis. Results: Under LUS guidance, sclerosant was injected successfully into the para-aortic soft tissue in all animals. There were no intraoperative complications in the acute animal group. Placement of sclerosant injection was successful in all nine chronic cases. Two pigs in the chronic study group died in the immediate postoperative period secondary to pneumothorax. No adverse neurologic, gastrointestinal, or other sequelae were observed in the remaining seven animals at 3–21 days postoperatively. After the animals were killed, we found no injuries to the aorta or esophagus, and histologic analysis demonstrated good placement of dye-labeled sclerosant with no compromise of aortic structural integrity. Conclusion: A laparoscopic approach to the aortic hiatus and NCPB is feasible. Further studies are warranted to evaluate this approach in patients who undergo staging laparoscopy for pancreatic cancer and are found to have unresectable disease.

Laparoscopic removal of an Angelchik prosthesis

Abstract. The use of Angelchik prosthetic rings for the surgical treatment of gastroesophageal reflux disease has been associated with frequent complications, including dysphagia and migration, erosion, or disruption of the ring. Although reports of the laparoscopic insertion of Angelchik rings have been published, there have been no descriptions of the laparoscopic removal of rings inserted at open laparotomy. Our group recently removed an Angelchik ring laparoscopically in an 80-year-old woman with progressive, refractory dysphagia and esophageal narrowing due to an Angelchik ring originally placed in 1981 via an upper midline incision at open operation. Upper endoscopy and dilatation had failed to provide symptom relief. An extensive adhesiolysis was performed laparoscopically, and the Angelchik ring was dissected free from the proximal stomach, diaphragm, and liver. The fibrous pseudocapsule enclosing the ring was divided, and the prosthesis was removed from around the esophagus and abdominal cavity. Intraoperative upper endoscopy confirmed resolution of the esophageal stricture. There were no intraoperative complications, and the patient was discharged home on the 3rd postoperative day tolerating a regular diet. Postoperatively, she experienced resolution of her dysphagia and complained only of mild reflux symptoms, which were easily controlled with famotidine and antireflux precautions. This case suggests that laparoscopic removal of Angelchik prosthetic rings is feasible for surgeons familiar with advanced laparoscopic procedures of the esophageal hiatus and should be considered for symptomatic patients, even if the ring was inserted via an open operation.

Delayed wound healing in diabetic (db/db) mice with Pseudomonas aeruginosa biofilm challenge: a model for the study of chronic wounds: A biofilm-challenged chronic wound model

Chronic wounds are a major clinical problem that lead to considerable morbidity and mortality. We hypothesized that an important factor in the failure of chronic wounds to heal was the presence of microbial biofilm resistant to antibiotics and protected from host defenses. A major difficulty in studying chronic wounds is the absence of suitable animal models. The goal of this study was to create a reproducible chronic wound model in diabetic mice by the application of bacterial biofilm. Six‐millimeter punch biopsy wounds were created on the dorsal surface of diabetic (db/db) mice, subsequently challenged with Pseudomonas aeruginosa (PAO1) biofilms 2 days postwounding, and covered with semiocclusive dressings for 2 weeks. Most of the control wounds were epithelialized by 28 days postwounding. In contrast, none of biofilm‐challenged wounds were closed. Histological analysis showed extensive inflammatory cell infiltration, tissue necrosis, and epidermal hyperplasia adjacent to challenged wounds—all indicators of an inflammatory nonhealing wound. Quantitative cultures and transmission electron microscopy demonstrated that the majority of bacteria were in the scab above the wound bed rather than in the wound tissue. The model was reproducible, allowed localized cutaneous wound infections without high mortality, and demonstrated delayed wound healing following a biofilm challenge. This model may provide an approach to study the role of microbial biofilms in chronic wounds as well as the effect of specific biofilm therapy on wound healing.

Time course study of delayed wound healing in a biofilm-challenged diabetic mouse model: Delayed healing in biofilm-colonized db/db mouse wounds

Bacterial biofilm has been shown to play a role in delaying wound healing of chronic wounds, a major medical problem that results in significant health care burden. A reproducible animal model could be very valuable for studying the mechanism and management of chronic wounds. Our previous work showed that Pseudomonas aeruginosa (PAO1) biofilm challenge on wounds in diabetic (db/db) mice significantly delayed wound healing. In this wound time course study, we further characterize the bacterial burden, delayed wound healing, and certain aspects of the host inflammatory response in the PAO1 biofilm‐challenged db/db mouse model. PAO1 biofilms were transferred onto 2‐day‐old wounds created on the dorsal surface of db/db mice. Control wounds without biofilm challenge healed by 4 weeks, consistent with previous studies; none of the biofilm‐challenged wounds healed by 4 weeks. Of the biofilm‐challenged wounds, 64% healed by 6 weeks, and all of the biofilm‐challenged wounds healed by 8 weeks. During the wound‐healing process, P. aeruginosa was gradually cleared from the wounds while the presence of Staphylococcus aureus (part of the normal mouse skin flora) increased. Scabs from all unhealed wounds contained 107 P. aeruginosa, which was 100‐fold higher than the counts isolated from wound beds (i.e., 99% of the P. aeruginosa was in the scab). Histology and genetic analysis showed proliferative epidermis, deficient vascularization, and increased inflammatory cytokines. Hypoxia inducible factor expression increased threefold in 4‐week wounds. In summary, our study shows that biofilm‐challenged wounds typically heal in approximately 6 weeks, at least 2 weeks longer than nonbiofilm‐challenged normal wounds. These data suggest that this delayed wound healing model enables the in vivo study of bacterial biofilm responses to host defenses and the effects of biofilms on host wound healing pathways. It may also be used to test antibiofilm strategies for treating chronic wounds.