Assessment of Chief Resident Practice Readiness in a Porcine Lab: A 4-Year Experience

OBJECTIVE

General surgery training prepares residents for the autonomous practice of surgery; however, assessment for readiness for independent practice presents several challenges. The simulation lab offers a safe and standardized environment for assessing the technical skills of a resident in the absence of numerous confounders of the real operating room. We describe our experience with evaluation and remediation of chief resident assessments in a porcine simulation lab.

DESIGN

Operative skill assessment of surgical residents was conducted using anesthetized porcine models. Procedure's representative of basic and complex operative skill was chosen for the assessment. Faculty assessed the residents using a checklist for the completion of all critical operative steps. A "failing" score or "critical fail" on a given procedure determined mandatory remediation. For remediation, faculty provided immediate post-procedure feedback on all errors, and residents were offered supervised practice. Residents were then retested to demonstrate competency.

SETTING

Large animal research center at Indiana University School of Medicine, Indianapolis, IN PARTICIPANTS: From 2017 to 2020, thirty-seven PGY5 residents participated in the porcine lab over a 4-year period. These general surgery residents were assessed at the beginning of their chief year.

RESULTS

There were a total of 6 residents that failed 1 or more procedures. There were no failures in the cholecystectomy, 3 failures for Nissen, 4 failures for Hand sewn anastomosis, and 1 failure for stapled anastomosis. Two residents failed 2 procedures. All residents received remediation with a faculty member and were subsequently able to perform the procedure competently.

CONCLUSIONS

A formal simulation-based assessment of procedural competence can identify technical performance deficiencies even at the chief resident level. Combined with a formal remediation program, such deficiencies can be addressed well in advance of residency graduation. Determining the relationship of such simulation-based assessments with operative performance is currently underway.

Optimizing Assessment of Surgical Knot Tying Skill

OBJECTIVES

Knot tying is a fundamental surgical skill. Existing knot tying models assess tying efficiency and errors but do not address respect for tissue. Development of a model that assesses tissue displacement during knot tying may provide a good surrogate for respect for tissue, allow detection of expertise, and offer an improved training platform for skill acquisition. This study aimed to develop a novel, low-cost, knot tying board (KTB) that collects objective, automated metrics of knot displacement, and assesses knot displacement by level of surgical expertise.

DESIGN

The novel KTB was developed in collaboration between engineering students and surgical educators. Joystick potentiometers were incorporated on 2 parallel rubber tubes to measure vertical and horizontal displacement while tying. Participants used a standardized technique to tie 1- and 2-handed knots. Differences in time and tubing displacement were compared among junior residents (postgraduate year 1-2), senior residents (postgraduate year 3-5), and attending surgeons; p < 0.05 was considered statistically significant.

SETTING

This study was conducted at the Indiana University Surgical Skills Center in Indianapolis, IN.

PARTICIPANTS

Forty-seven residents and faculty participated in the study (26 juniors, 14 seniors, 7 attendings).

RESULTS

KTB development required 100 hours and $70.00. The attending surgeons tied 2-handed knots faster and with significantly more vertical tubing displacement than residents. Senior residents tied knots significantly faster but with similar tubing displacement as juniors. Similar trends were found for 1-handed knots.

CONCLUSIONS

A novel, low-cost KTB was developed to measure knot displacement as a surrogate for tissue handling. The new performance metric of vertical knot displacement proved more sensitive in detecting performance differences among groups compared with horizontal knot displacement. This board and its novel metrics may promote the development of robust knot tying skill by residents.

Anthropoid primate-specific retroviral element THE1B controls expression of CRH in placenta and alters gestation length

Pregnancy and parturition are intricately regulated to ensure successful reproductive outcomes. However, the factors that control gestational length in humans and other anthropoid primates remain poorly defined. Here, we show the endogenous retroviral long terminal repeat transposon-like human element 1B (THE1B) selectively controls placental expression of corticotropin-releasing hormone (CRH) that, in turn, influences gestational length and birth timing. Placental expression of CRH and subsequently prolonged gestational length were found in two independent strains of transgenic mice carrying a 180-kb human bacterial artificial chromosome (BAC) DNA that contained the full length of CRH and extended flanking regions, including THE1B. Restricted deletion of THE1B silenced placental CRH expression and normalized birth timing in these transgenic lines. Furthermore, we revealed an interaction at the 5′ insertion site of THE1B with distal-less homeobox 3 (DLX3), a transcription factor expressed in placenta. Together, these findings suggest that retroviral insertion of THE1B into the anthropoid primate genome may have initiated expression of CRH in placental syncytiotrophoblasts via DLX3 and that this placental CRH is sufficient to alter the timing of birth.

The proper timing of delivery is critical during pregnancy; if too early or too late, the baby will be at risk of serious health problems and even death. Corticotropin-releasing hormone (CRH) is a protein that can be detected in maternal blood, and its concentration correlates with the timing of birth. In humans and other anthropoid primates, CRH is made by the placenta, whereas in other mammals, it is produced in a specialized region of the brain. To understand the regulation and evolution of this key protein, we inserted the human CRH gene and nearby regions into the mouse genome, which resulted in human CRH expression in the mouse placenta. Mouse litters that make CRH in their placentas are born later than control mice, showing that CRH can directly affect birth timing. Using our mouse model, we then selectively deleted a remnant of an ancient retrovirus that is normally found in the DNA of anthropoid primates and demonstrated that this specific region controls expression of CRH in the placenta. Deletion of this region also restored normal birth timing in the mice by eliminating CRH production from the placenta. We propose that retroviral regulation of CRH in the placenta may be a mechanism of controlling birth timing in humans and other anthropoid primates.

Structured photocathodes for improved high-energy x-ray efficiency in streak cameras

We have designed and fabricated a structured streak camera photocathode to provide enhanced efficiency for high energy X-rays (1-12 keV). This gold coated photocathode was tested in a streak camera and compared side by side against a conventional flat thin film photocathode. Results show that the measured electron yield enhancement at energies ranging from 1 to 10 keV scales well with predictions, and that the total enhancement can be more than 3×. The spatial resolution of the streak camera does not show degradation in the structured region. We predict that the temporal resolution of the detector will also not be affected as it is currently dominated by the slit width. This demonstration with Au motivates exploration of comparable enhancements with CsI and may revolutionize X-ray streak camera photocathode design.

A multi-wavelength, high-contrast contact radiography system for the study of low-density aerogel foams

A multi-wavelength, high contrast contact radiography system has been developed to characterize density variations in ultra-low density aerogel foams. These foams are used to generate a ramped pressure drive in materials strength experiments at the National Ignition Facility and require precision characterization in order to reduce errors in measurements. The system was used to characterize density variations in carbon and silicon based aerogels to ∼10.3% accuracy with ∼30 μm spatial resolution. The system description, performance, and measurement results collected using a 17.8 mg/cc carbon based JX-6 (C20H30) aerogel are discussed in this manuscript.

High quantum efficiency photocathode simulation for the investigation of novel structured designs

A computer model in CST Studio Suite has been developed to evaluate several novel geometrically enhanced photocathode designs. This work was aimed at identifying a structure that would increase the total electron yield by a factor of two or greater in the 1-30 keV range. The modeling software was used to simulate the electric field and generate particle tracking for several potential structures. The final photocathode structure has been tailored to meet a set of detector performance requirements, namely, a spatial resolution of <40 μm and a temporal spread of 1-10 ps. We present the details of the geometrically enhanced photocathode model and resulting static field and electron emission characteristics.

A geophysical shock and air blast simulator at the National Ignition Facility

The energy partitioning energy coupling experiments at the National Ignition Facility (NIF) have been designed to measure simultaneously the coupling of energy from a laser-driven target into both ground shock and air blast overpressure to nearby media. The source target for the experiment is positioned at a known height above the ground-surface simulant and is heated by four beams from the NIF. The resulting target energy density and specific energy are equal to those of a low-yield nuclear device. The ground-shock stress waves and atmospheric overpressure waveforms that result in our test system are hydrodynamically scaled analogs of full-scale seismic and air blast phenomena. This report summarizes the development of the platform, the simulations, and calculations that underpin the physics measurements that are being made, and finally the data that were measured. Agreement between the data and simulation of the order of a factor of two to three is seen for air blast quantities such as peak overpressure. Historical underground test data for seismic phenomena measured sensor displacements; we measure the stresses generated in our ground-surrogate medium. We find factors-of-a-few agreement between our measured peak stresses and predictions with modern geophysical computer codes.

Direct Inoculation of Mycobacteriumavium Subspecies Paratuberculosis Into Ileocecal Peyer’s Patches Results in Colonization of the Intestine in a Calf Model

The objective of this study was to develop an intestinal model of Mycobacterium avium subspecies paratuberculosis ( Map) infection in the calf for evaluation of mucosal pathology and local and systemic immunologic responses. Map was inoculated into Peyer’s patches of young calves using a right flank surgical approach in standing calves to exteriorize the ileocecal junction. Inoculum doses ranging from 103 to 109 colony-forming units of strain K10 Map were injected through the serosal surface into Peyer’s patches of the distal ileum near the ileocecal valve. Fecal samples were collected for culture from each calf weekly until termination of the study. Calves were necropsied at 7, 30, 60, and 90 days after infection, when inoculation sites, lymph nodes, spleen, and peripheral blood were collected for evaluation. Ileocecal lymph nodes were consistently colonized by Map in the 105 to 109 groups. The ileocecal valve was also colonized in 107 and 109 groups. This correlated with fecal culture results as infected calves intermittently shed Map in their feces throughout the study. Granulomatous lesions with giant cells and acid-fast bacilli at the ileocecal junction, ileocecal lymph nodes, and lamina propria of high-dose animals (107 and 109) were identified from each time point. Flow cytometry was used to detect antigen-specific production of interferon-γ and interleukin-4 locally (ileocecal lymph node) and systemically (peripheral blood mononuclear cells), which defined distinct immunologic profiles in low-dose and high-dose calves. This study demonstrates intestinal Map infection via Peyer’s patch inoculation, a novel model with many shared features of natural Map infection.

Inducible nitric oxide synthase immunoreactivity in the granulomatous intestinal lesions of naturally occurring bovine Johne's disease

Inducible nitric oxide synthase (iNOS) is important in the control of a number of intracellular pathogens, including mycobacteria, and is a marker of classic macrophage activation. In human granulomatous diseases such as leprosy, a spectrum of granulomatous lesions is described, ranging from the tuberculoid to lepromatous types. Tuberculoid granulomas are associated with enhanced iNOS production and improved clinical outcomes over the lepromatous types. The aim of this study is to determine whether an association exists between morphology of bovine Johne's disease granulomas and lesion macrophage effector functions. To accomplish this, we retrospectively evaluated 24 cases of bovine Johne's disease. In each case, we recorded the predominant granuloma morphology and evaluated iNOS immunoreactivity and bacterial burden by acid-fast stains and mycobacterial immunolabeling. The results of this study demonstrate that all cases had granulomas with features most similar to the lepromatous type. This morphology correlated with heavy bacterial burdens demonstrated by acid-fast staining and mycobacterial immunoreactivity. None of the cases had high expression of iNOS in mycobacterial-positive granulomas. When iNOS immunoreactivity was identified, it was usually located near the crypts and was distinct from the granulomatous foci.

Cellular distribution of anionic antimicrobial peptide in normal lung and during acute pulmonary inflammation

Anionic peptides (APs) are small antimicrobial peptides present in human and ovine lung. In this study APs were also detected in bovine lung, and production of APs in lungs with acute inflammation induced by various stimuli was determined. The distribution and intensity of APs were determined by immunohistochemistry in lungs of 1) neonatal calves (1-3 days of age) inoculated with Mannheimia (Pasteurella) haemolytica, a known inducer of the bovine beta-defensin lingual antimicrobial peptide (LAP) or pyrogen-free saline (PFS), and 2) growing calves (3 months of age) similarly inoculated with M. haemolytica, a lipopolysaccharide (LPS) from M. haemolytica, an LPS-associated protein from M. haemolytica, or PFS. APs were also detected by western blots with the same antibody in lungs of the calves above, as well as in calves inoculated with Pseudomonas aeruginosa, and an adult cow. Anionic peptide (AP) immunoreactivity was detected in bands (approximate weights) in the western blots of lung at 28-30 (strongest signal), 31, 45, and 52-60 kd regardless of inoculum. The adult cow lacked bands at 45 kd, but it had additional bands at 64 (inconsistently) and 35-38 kd. All these band sizes are consistent with those of the western blots of human and ovine lung. The cellular distribution of APs in lung of neonatal and growing cattle was similar to that in lung of human and sheep. In lungs with acute inflammation induced by live bacteria, LPS, or protein, AP distribution and intensity were similar to those in control (PFS-inoculated) lungs and slightly decreased in bronchioles. This work demonstrates that AP is present in lung of cattle and is thereby conserved among two ruminant species and man. Distribution and intensity of AP production are not enhanced by infection or acute inflammation and are decreased in bronchioles, which suggests that AP is not induced like beta-defensins such as LAP, but, instead, is produced constitutively.

Workgroup issue paper: Indicators and assessment of agricultural sustainability : Methods of Assessing Agricultural Sustainability

Sustainability is emerging as one of the most fundamental concepts for assessing the overall state of an agricultural production system. Essentially, this concept assumes that if a production system is sustainable indefinitely, then it is acceptable. But almost any system is sustainable if sufficient resources are committed to it! So it's obvious that an uncritical adoption of the idea is not acceptable.