Body Habitus and Dynamic Surgical Conditions Independently Impair Pulmonary Mechanics during Robotic-assisted Laparoscopic Surgery.

BACKGROUND: Body habitus, pneumoperitoneum, and Trendelenburg positioning may each independently impair lung mechanics during robotic laparoscopic surgery. This study hypothesized that increasing body mass index is associated with more mechanical strain and alveolar collapse, and these impairments are exacerbated by pneumoperitoneum and Trendelenburg positioning. METHODS: This cross-sectional study measured respiratory flow, airway pressures, and esophageal pressures in 91 subjects with body mass index ranging from 18.3 to 60.6 kg/m2. Pulmonary mechanics were quantified at four stages: (1) supine and level after intubation, (2) with pneumoperitoneum, (3) in Trendelenburg docked with the surgical robot, and (4) level without pneumoperitoneum. Subjects were stratified into five body mass index categories (less than 25, 25 to 29.9, 30 to 34.9, 35 to 39.9, and 40 or higher), and respiratory mechanics were compared over surgical stages using generalized estimating equations. The optimal positive end-expiratory pressure settings needed to achieve positive end-expiratory transpulmonary pressures were calculated. RESULTS: At baseline, transpulmonary driving pressures increased in each body mass index category (1.9 ± 0.5 cm H2O; mean difference ± SD; P < 0.006), and subjects with a body mass index of 40 or higher had decreased mean end-expiratory transpulmonary pressures compared with those with body mass index of less than 25 (-7.5 ± 6.3 vs. -1.3 ± 3.4 cm H2O; P < 0.001). Pneumoperitoneum and Trendelenburg each further elevated transpulmonary driving pressures (2.8 ± 0.7 and 4.7 ± 1.0 cm H2O, respectively; P < 0.001) and depressed end-expiratory transpulmonary pressures (-3.4 ± 1.3 and -4.5 ± 1.5 cm H2O, respectively; P < 0.001) compared with baseline. Optimal positive end-expiratory pressure was greater than set positive end-expiratory pressure in 79% of subjects at baseline, 88% with pneumoperitoneum, 95% in Trendelenburg, and ranged from 0 to 36.6 cm H2O depending on body mass index and surgical stage. CONCLUSIONS: Increasing body mass index induces significant alterations in lung mechanics during robotic laparoscopic surgery, but there is a wide range in the degree of impairment. Positive end-expiratory pressure settings may need individualization based on body mass index and surgical conditions.

Intraoperative Ultrasound Guidance With an Ultrasound-Visible Clip: A Practical and Cost-effective Option for Breast Cancer Localization.

OBJECTIVES: In partial mastectomy (PM) or lumpectomy, ultrasound (US) localization avoids discomfort and additional procedures associated with wire localization. The purpose of this study was to evaluate the association between ultrasound-visible clip (UVC) use at the time of biopsy and US use during resection, hypothesizing that UVCs facilitate US localization and reduce costs compared with traditional radiopaque clips or no clip placement. METHODS: The study population consisted of adult female patients with breast cancer undergoing PM or lumpectomy at our institution between 2014 and 2016. The core biopsy clip type and localization method during PM were characterized as wire localization versus US localization, and associations were estimated with multivariable regression models. For the cost evaluation, breast biopsy data were obtained from the Department of Radiology. RESULTS: Among 674 patients, 490 had data on localization and the clip type. Ultrasound-visible clip placement at biopsy increased US use during resection by 13% (95% confidence interval, 6%-21%). There was no difference in the total specimen weight with US versus wire localization. The cost savings for using UVCs for the 2209 patients who underwent breast biopsy from 2014 to 2016 was $36,000. CONCLUSIONS: This study demonstrates that US localization for PM is feasible at a single institution and cost-effective when facilitated by UVCs. Placement of a UVC at the time of biopsy is recommended, as it is cost-effective and avoids the discomfort and inconvenience of wire localization.

Outcomes of Colectomy and Proctectomy According to Surgeon Training: General vs Colorectal Surgeons.

BACKGROUND: Colectomies and proctectomies are commonly performed by both general surgeons (GS) and colorectal surgeons (CRS). The aim of our study was to examine the outcomes of elective colectomy, urgent colectomy, and elective proctectomy according to surgeon training. STUDY DESIGN: Data were obtained from the Vizient database for adults who underwent elective colectomy, urgent colectomy, and elective proctectomy from 2020 to 2022. Operations performed in the setting of trauma and patients within the database's highest relative expected mortality risk group were excluded. Outcomes were compared according to surgeon's specialty: GS vs CRS. The primary outcome was in-hospital mortality. The secondary outcome was in-hospital complication rate. Data were analyzed using multivariate logistic regression. RESULTS: Of 149,516 elective colectomies, 75,711 (50.6%) were performed by GS and 73,805 (49.4%) by CRS. Compared with elective colectomies performed by CRS, elective colectomies performed by GS had higher rates of complications (4.9% vs 3.9%, odds ratio [OR] 1.23, 95% CI 1.17 to 1.29, p < 0.01) and mortality (0.5% vs 0.2%, OR 2.06, 95% CI 1.72 to 2.47, p < 0.01). Of 71,718 urgent colectomies, 54,680 (76.2%) were performed by GS, whereas 17,038 (23.8%) were performed by CRS. Compared with urgent colectomies performed by CRS, urgent colectomies performed by GS were associated with higher rates of complications (12.1% vs 10.4%, OR 1.14, 95% CI 1.08 to 1.20, p < 0.01) and mortality (5.1% vs 2.3%, OR 2.08, 95% CI 1.93 to 2.23, p < 0.01). Of 43,749 elective proctectomies, 28,458 (65.0%) were performed by CRS and 15,291 (35.0%) by GS. Compared with proctectomies performed by CRS, those performed by GS were associated with higher rates of complications (5.3% vs 4.4%, OR 1.16, 95% CI 1.06 to 1.27, p < 0.01) and mortality (0.3% vs 0.2%, OR 1.49, 95% CI 1.02 to 2.20, p = 0.04). CONCLUSIONS: In this nationwide study, colectomies and proctectomies performed by CRS were associated with improved outcomes compared with GS. Hospitals without a CRS on staff should consider prioritizing recruiting CRS specialists.

Effects of T- and R-state stabilization on deoxyhemoglobin-nitrite reactions and stimulation of nitric oxide signaling.

Recent data suggest that transitions between the relaxed (R) and tense (T) state of hemoglobin control the reduction of nitrite to nitric oxide (NO) by deoxyhemoglobin. This reaction may play a role in physiologic NO homeostasis and be a novel consideration for the development of the next generation of hemoglobin-based blood oxygen carriers (HBOCs, i.e. artificial blood substitutes). Herein we tested the effects of chemical stabilization of bovine hemoglobin in either the T- (THb) or R-state (RHb) on nitrite-reduction kinetics, NO-gas formation and ability to stimulate NO-dependent signaling. These studies were performed over a range of fractional saturations that is expected to mimic biological conditions. The initial rate for nitrite-reduction decreased in the following order RHb>bHb>THb, consistent with the hypothesis that the rate constant for nitrite reduction is faster with R-state Hb and slower with T-state Hb. Moreover, RHb produced more NO-gas and inhibited mitochondrial respiration more potently than both bHb and THb. Interestingly, at low oxygen fractional saturations, THb produced more NO and stimulated nitrite-dependent vasodilation more potently than bHb despite both derivatives having similar initial rates for nitrite reduction and a more negative reduction potential in THb versus bHb. These data suggest that cross-linking of bovine hemoglobin in the T-state conformation leads to a more effective coupling of nitrite reduction to NO-formation. Our results support the model of allosteric regulation of nitrite reduction by deoxyhemoglobin and show that cross-linking hemoglobins in distinct quaternary states can generate products with increased NO yields from nitrite reduction that could be harnessed to promote NO-signaling in vivo.

Optimal Initial Positioning of Chest Tubes to Prevent Retained Hemothorax Using a Novel Steerable Chest Tube With Extendable Infusion Cannula.

INTRODUCTION: With blunt and penetrating trauma to the chest, warfighters and civilians frequently suffer from punctured lung (pneumothorax) and/or bleeding into the pleural space (hemothorax). Optimal management of this condition requires the rapid placement of a chest tube to evacuate as much of the blood and air as possible. Incomplete drainage of blood leading to retained hemothorax may be the result of the final tube tip position not being in contact with the blood collections. To address this problem, we sought to develop a "steerable" chest tube that could be accurately placed or repositioned into a specific desired position in the pleural space to assure optimal drainage. An integrated infusion cannula was added for the instillation of anticoagulants to maintain tube patency, thrombolytics for clot lysis, and analgesics for pain control if required. MATERIALS AND METHODS: A triple-lumen tube was designed to provide a channel for a pull-wire which was wound around an axle integrated into a small proximal handle and controlled by a ratcheted thumbwheel. Tension on the wire creates an arc on the tube that allows for positioning. In vitro testing focused on the relationship between the tension on the pull-wire and the resultant arc. Two adult cadavers and two anesthetized pigs were used to study the feasibility of accurate tube placement. After a brief training session, providers were asked to place tubes inferiorly along the diaphragm where blood was anticipated to accumulate or at the apex of the lung for pneumothorax. Success was determined with fluoroscopic images and was judged as a tube tip lying in the targeted position. RESULTS: The design was prototyped with an extruded polyvinyl chloride multilumen tube and a 3D printed tensioning handle. In vitro studies showed that one turn of the thumbwheel created 70° to 90° of arc of the tube. Cadaver and animal studies showed consistent success in the desired placement of the tube at or near the lateral diaphragm or in the apex. Attempts were also successful by surgical residents with minimal training. CONCLUSIONS: Initial preliminary studies on a novel steerable chest tube have demonstrated the ability to appropriately position the tube in a desired location. The addition of an extendable cannula will allow for safe clot lysis or maintained tube patency. Additional studies are planned to confirm the benefit of this device in preventing retained hemothorax.

Gradual adoption of needle biopsy for breast lesions in a rural state.

BACKGROUND: Minimally invasive breast biopsy (MIBB) is the standard of care for the diagnosis of breast cancer, with consensus guidelines suggesting MIBB goals of 90% of total biopsies. In a previous study of patients in the rural state of Vermont, USA (population size of 640,000), rural breast cancer patients had open biopsies 42% of the time compared to 29% of urban breast cancer patients. The aim of this study was to assess overall population-based biopsy trends in Vermont. METHODS: The Vermont Breast Cancer Surveillance System (VBCSS) was used to identify women receiving MIBB and excisional breast biopsies in Vermont. Patient zip code at the time of initial biopsy was used to determine the patient residence rurality by rural-urban commuting area codes (RUCA 2.0™). RESULTS: There were 9122 diagnostic episodes from 1999 to 2018. MIBB was the initial biopsy method in 7524 (82.5%) cases, while surgical excision was the initial biopsy method in 1598 (17.5%) cases. A linear trend fit estimated an increase of 1.3% per year (p < 0.001, 95% CI 1.1%-1.5%) in the fraction of patients undergoing MIBB. Patients living in rural areas were less likely to receive MIBB (78.5%) than those living in urban areas (94.9%), p < 0.001. Multivariate analysis showed that urban patients and those patients in the years 2014-2018 were more likely to receive MIBB (OR 5.00, 95% CI 4.13-6.05 [p < 0.05] and OR 4.41, 95%CI 3.68-5.28 [p < 0.05], respectively). The rate of MIBB for rural patients increased and met the 90% quality standard in 2013 and ultimately matched urban patient rates of MIBB in 2018. CONCLUSIONS: For the first time, we show that MIBB usage is above 90% in the state of Vermont and that there no longer exist disparities in breast biopsies between urban and rural patients or rural/urban facilities in the state, overall.

Geographic Coverage and Verification of Trauma Centers in a Rural State: Highlighting the Utility of Location Allocationfor Trauma System Planning.

BACKGROUND: Care at verified trauma centers has improved survival and functional outcomes, yet determining the appropriate location of potential trauma centers is often driven by factors other than optimizing system-level patient care. Given the importance of transport time in trauma, we analyzed trauma transport patterns in a rural state lacking an organized trauma system and implemented a geographic information system to inform potential future trauma center locations. STUDY DESIGN: Data were collected on trauma ground transport during a 3-year period (2014 through 2016) from the Statewide Incident Reporting Network database. Geographic information system mapping and location-allocation modeling of the best-fit facility for trauma center verification was computed using trauma transport patterns, population density, road network layout, and 60-minute emergency medical services transport time based on current transport protocols. RESULTS: Location-allocation modeling identified 2 regional facilities positioned to become the next verified trauma centers. The proportion of the Vermont population without access to trauma center care within 60 minutes would be reduced from the current 29.68% to 5.81% if the identified facilities become verified centers. CONCLUSIONS: Through geospatial mapping and location-allocation modeling, we were able to identify gaps and suggest optimal trauma center locations to maximize population coverage in a rural state lacking a formal, organized trauma system. These findings could inform future decision-making for targeted capacity improvement and system design that emphasizes more equitable access to trauma center care in Vermont.

A complicated abscess from a dropped gallstone.

Laparoscopic cholecystectomies represent one of the most common procedures of General Surgery. Dropped gallstones during laparoscopic cholecystectomy is a rare occurrence but can potentially lead to morbid complications. We present a rare case of a broncho-pleuro-cutaneous fistula in a patient with recurrent abscess formations after an elective laparoscopic cholecystectomy. The fistula formed over 3 years from a gallstone that eroded through the diaphragm, into the pleural space, and eventually into a terminal bronchiole. Bilirubin staining within the fistula tract was confirmed on hematoxylin and eosin staining.

Habitat Modification by the Leaf-Cutter Ant, Atta cephalotes, and Patterns of Leaf-Litter Arthropod Communities.

Ecosystem engineers are profoundly important in many biological communities. A Neotropical taxonomic group considered to have engineering effects is the Formicidae (ants). Leaf-cutter ants (LCAs), in particular, which form extensive colonies of millions of individuals, can be important ecosystem engineers in these environments. While the effects of LCAs on plant community structure and soil chemistry are well-studied, their effects on consumers are poorly understood. Therefore, we examined the indirect effects of the LCA Atta cephalotes L. on the leaf-litter arthropod community. We compared abundance and diversity patterns at ant nests to areas distant from nests, utilizing both a factorial design and gradient analysis for both nocturnal and diurnal arthropods. We found that arthropod abundance and diversity was significantly lower for multiple taxonomic groups and trophic levels near leaf-cutter nests, and this pattern was strongest at night. Exceptions to this pattern included two morphospecies of Collembola that were more abundant on nests, suggesting some specialization for these species. For the gradient analysis, abundance increased exponentially for most groups of arthropods. However, for the dominant arthropod species, the amphipod Cerrorchestia hyloraina Lindeman, a quadratic function was the best fit curvilinear model for abundance. It appeared that C. hyloraina had maximal abundance at the transition between nest site and less disturbed forest. These results indicate that LCA activity has a strong effect on the leaf-litter arthropod community, adding to spatial heterogeneity within neotropical forests. These effects may translate into changes in important ecological processes such as nutrient cycling and food web function.