SAGES masters program: the top 10 seminal articles for the laparoscopic left and sigmoid colectomy pathway for complex disease.

BACKGROUND: The SAGES University Colorectal Masters Program is a structured educational curriculum that is designed to aid practicing surgeons develop and maintain knowledge and technical skills for laparoscopic colorectal surgery. The Colorectal Pathway is based on three anchoring procedures (laparoscopic right colectomy, laparoscopic left and sigmoid colectomy for uncomplicated and complex disease, and intracorporeal anastomosis for minimally invasive right colectomy) corresponding to three levels of performance (competency, proficiency and mastery). This manuscript presents focused summaries of the top 10 seminal articles selected for laparoscopic left and sigmoid colectomy for complex benign and malignant disease. METHODS: A systematic literature search of Web of Science for the most cited articles on the topic of laparoscopic complex left/sigmoid colectomy yielded 30 citations. These articles were reviewed and ranked by the SAGES Colorectal Task Force and invited subject experts according to their citation index. The top 10 ranked articles were then reviewed and summarized, with emphasis on relevance and impact in the field, study findings, strength and limitations and conclusions. RESULTS: The top 10 seminal articles selected for the laparoscopic left/sigmoid colectomy for complex disease anchoring procedure include advanced procedures such as minimally invasive splenic flexure mobilization techniques, laparoscopic surgery for complicated and/or diverticulitis, splenic flexure tumors, complete mesocolic excision, and other techniques (e.g., Deloyers or colonic transposition in cases with limited colonic reach after extended left-sided resection). CONCLUSIONS: The SAGES Colorectal Masters Program top 10 seminal articles selected for laparoscopic left and sigmoid colectomy for complex benign and malignant disease anchoring procedure are presented. These procedures were the most essential in the armamentarium of practicing surgeons that perform minimally invasive surgery for complex left and sigmoid colon pathology.

Lift vs. drag based mechanisms for vertical force production in the smallest flying insects.

We used computational fluid dynamics to determine whether lift- or drag-based mechanisms generate the most vertical force in the flight of the smallest insects. These insects fly at Re on the order of 4-60 where viscous effects are significant. Detailed quantitative data on the wing kinematics of the smallest insects is not available, and as a result both drag- and lift-based strategies have been suggested as the mechanisms by which these insects stay aloft. We used the immersed boundary method to solve the fully-coupled fluid-structure interaction problem of a flexible wing immersed in a two-dimensional viscous fluid to compare three idealized hovering kinematics: a drag-based stroke in the vertical plane, a lift-based stroke in the horizontal plane, and a hybrid stroke on a tilted plane. Our results suggest that at higher Re, a lift-based strategy produces more vertical force than a drag-based strategy. At the Re pertinent to small insect hovering, however, there is little difference in performance between the two strategies. A drag-based mechanism of flight could produce more vertical force than a lift-based mechanism for insects at Re<5; however, we are unaware of active fliers at this scale.

Evaluation of the impact of enhanced recovery after surgery protocol implementation on maternal outcomes following elective cesarean delivery.

BACKGROUND: Despite significant improvements in outcomes following non-obstetric surgery with implementation of enhanced recovery after surgery (ERAS) protocols, development of these protocols for cesarean delivery is lacking. We evaluated implementation of an ERAS protocol for patients undergoing elective cesarean delivery, specifically the effect on opioid consumption, pain scores and length of stay as well as complications and re-admissions. METHODS: An ERAS protocol was developed and implemented for women undergoing elective cesarean delivery. The protocol construction included specific evidence-based items applicable to peripartum management and these were grouped into the three major phases of patient care: antepartum, intrapartum and postpartum. A before-and-after study design was used to compare maternal outcomes. To account for confounders between groups, a propensity matched scoring analysis was used. The primary outcome was postpartum opioid use in mg-morphine equivalents (MMEQ). RESULTS: We included 357 (n=196 before; n=161 after) women who underwent elective cesarean delivery. A significant difference in opioid consumption (28.4 ±â€¯24.1 vs 46.1 ±â€¯37.0 MMEQ, P <0.001) and in per-day postoperative opioid consumption (10.9 ±â€¯8.7 vs 15.1 ±â€¯10.3 MMEQ, P <0.001), lower peak pain scores (7 [5-9] vs 8 [7-9], P=0.007) and a shorter hospital length of stay (2.5 ±â€¯0.5 vs 2.9 ±â€¯1.2 days, P <0.001) were found after the introduction of the ERAS protocol. CONCLUSIONS: Implementation of ERAS protocols for elective cesarean delivery is associated with significant improvements in analgesic and recovery outcomes. These improvements in quality of care suggest ERAS protocols should be considered for elective cesarean delivery.

Morning report: combining education with patient handover.

INTRODUCTION: The advent of resident work hour restrictions has challenged us to train residents within a shorter working week, while ensuring continuity of patient care. We instituted morning report (MR) at the University of Virginia primarily as a means to accomplish these objectives. Serendipitously MR has become an integral educational tool for the surgical residents. The rationale for the format and instructional design are discussed in the context of learning theory. METHODS: The chief residents as primary stakeholders were strongly encouraged to play a leadership role in designing MR. A faculty- led didactic format was rejected because of the importance of focusing on resident team building, and leadership, but poor faculty participation was also an issue. RESULTS: The initial obstacles included timing, and designing the format. CONCLUSIONS: MR is an opportunity for residents to exercise and improve their knowledge, leadership, presentation and problem-solving skills. We would hypothesise that the advantages for teaching are many and include that residents are prepared for actual clinical problems in a supportive environment with opportunities for immediate feedback and assessment. Reports of educational effectiveness of MR are mostly anecdotal and further studies are needed to characterise the types of learning and teaching that occur during MR and to document educational effectiveness.

Implant-associated infections: an overview.

The discovery of a 5500-year-old dental implant near Gebel Ramlah, Egypt, marks the earliest discovery of a medical prosthesis. It would not be until the 20th century, however, that this ancient concept would resurface on a wide scale basis. With the introduction of physiologically inert biomaterials in the 1950s, the field of surgical implants has emerged as arguably one of the greatest medical advancements of our time. It is now estimated that millions of patients worldwide have received some type of prosthesis. This forces us to appreciate the impact of implant-associated infections on patients today and mandates that we as a medical community be prepared to manage these infections effectively. This article provides an in-depth review of the current most commonly used prosthetic devices and the infections that accompany them. We examine the epidemiology, diagnosis, prevention, and treatment of various implant-associated infections within the fields of general, plastic, orthopedic, dental, and neurosurgery. We will highlight the recent technological advancements and future prospects. We will also draw attention to the need for further research in this ever growing field.

Severity of coronary artery calcification by electron beam computed tomography predicts silent myocardial ischemia.

BACKGROUND: Detection of subclinical coronary artery disease (CAD) before the development of life-threatening cardiac complications has great potential clinical relevance. Electron beam computed tomography (EBCT) is currently the only noninvasive test that can detect CAD in all stages of its development and thus has the potential to be an excellent screening technique for identifying asymptomatic subjects with underlying myocardial ischemia. METHODS AND RESULTS: Over 2.5 years, we prospectively studied 3895 generally asymptomatic subjects with EBCT, 411 of whom had stress myocardial perfusion tomography (SPECT) within a close (median, 17 days) time period. SPECT and exercise treadmill results were compared with the coronary artery calcium score (CACS) as assessed by EBCT. The total CACS identified a population at high risk for having myocardial ischemia by SPECT although only a minority of subjects (22%) with an abnormal EBCT had an abnormal SPECT. No subject with CACS <10 had an abnormal SPECT compared with 2.6% of those with scores from 11 to 100, 11.3% of those with scores from 101 to 399, and 46% of those with scores >/=400 (P<0.0001). CACS predicted an abnormal SPECT regardless of subject age or sex. CONCLUSIONS: CACS identifies a high-risk group of asymptomatic subjects who have clinically important silent myocardial ischemia. Our results support the role of EBCT as the initial screening tool for identifying individuals at various stages of CAD development for whom therapeutic decision making may differ considerably.

Balloon dilation of unoperated coarctation of the aorta: short- and intermediate-term results.

Balloon dilation is effective in the immediate relief of obstruction due to unoperated coarctation of the aorta. However, the long-term benefits and complications of this procedure have not been established. Thirty-three patients underwent balloon dilation of unoperated coarctation using a percutaneous technique from November 1983 to December 1985. High quality biplane angiography was performed before and after dilation. Follow-up was obtained in 20 patients from 6 to 31 months following dilation. Angiography was performed at follow-up in 10, nuclear magnetic resonance (NMR) imaging in 10 and both NMR imaging and angiography in 3. Balloon dilation was successful in 31 of the 33 patients with a decrease in average systolic pressure gradient from 46 to 8 mm Hg. There was no significant change in gradient on follow-up physical examination and at recatheterization in 10 patients. In addition, there was no evidence of restenosis on follow-up angiography and NMR imaging. In two patients, a small aneurysm formed at the site of balloon dilation. Balloon dilation of unoperated coarctation is effective, providing lasting relief of coarctation gradient and no evidence of restenosis. However, because of the uncertain natural history of aneurysms after dilation, this procedure should be considered investigational until further follow-up on patients with and without an aneurysm is available.

Assessment of tissue iron overload by nuclear magnetic resonance imaging.

PURPOSE: The ability of stored intracellular iron to enhance magnetic susceptibility forms the basis by which tissue iron can be detected by nuclear magnetic resonance (NMR) imaging. We used this technique to assess myocardial, spleen, and liver iron content in patients with known or suspected iron overload disorders. PATIENTS AND METHODS: Spin echo NMR images were obtained in 30 patients; 20 had chronic anemias treated by multiple blood transfusions, five had idiopathic hemochromatosis, and five had non-hemochromatotic liver disease with elevated serum ferritin levels and no stainable iron on liver biopsy. The acquisition of oblique images through the short axis of the left ventricle permitted assessment of left ventricular function, while demonstrating the liver and spleen on the same image. Iron content was assessed using a signal intensity ratio of organ (spleen, liver, or myocardium) to skeletal muscle. RESULTS: In patients with multiple blood transfusions, iron content was highest in liver, followed by the spleen. Significant iron overload was detected in the myocardium of only one patient. Left ventricular systolic wall thickening was normal in patients receiving multiple blood transfusions. Two patients with treated idiopathic hemochromatosis had normal signal intensity ratios, and three untreated patients had evidence of significant deposits of iron in the liver and spleen as indicated by a reduction in signal intensity ratios (0.2 +/- 0.01 and 0.9 +/- 0.01, respectively). Five patients with non-hemochromatotic liver disease and high serum ferritin levels had normal signal intensity ratios by NMR imaging. CONCLUSION: NMR imaging is a useful method of detecting tissue iron and distinguishing disease due to iron overload. Myocardial iron deposition is a late event, occurring after accumulation of iron in the spleen and liver.

Ultrasonic demonstration of ectopic ureterocele.

The gray scale ultrasound findings in two children with ectopic ureterocele are presented and correlated with traditional radiographic findings. In one case, the diagnosis was made in utero, utilizing ultrasound. The examination is noninvasive and performed quickly, and it may be able to replace the intravenous pyelogram in the initial evaluation of patients suspected of having such congenital anomalies. Retrograde cystography will still be necessary to detect vesicoureteral reflux.

Muscle volume, MRI relaxation times (T2), and body composition after spaceflight.

Postflight changes in muscle volume, calf muscle transverse relaxation time, and total body composition were measured in 4 crewmembers after a 17-day mission and in 14-16 crewmembers in multiple shuttle/Mir missions of 16- to 28-wk duration. During the 17-day mission, all muscle regions except the hamstrings significantly decreased 3-10% compared with baseline. During the shuttle/Mir missions, there were significant decreases in muscle volume (5-17%) in all muscle groups except the neck. These changes, which reached a new steady state by 4 mo of flight or less, were reversed within 30-60 days after landing. Postflight swelling and elevation of calf muscle transverse relaxation time persisted for several weeks after flight, which suggests possible muscle damage. In contrast to the 17-day flight, in which loss in fat, but not lean body mass, was found (25), losses in bone mineral content and lean body mass, but not fat, were seen after the longer shuttle/Mir missions. The percent losses in total body lean body mass and bone mineral content were similar at approximately 3.4-3.5%, whereas the pelvis demonstrated the largest regional bone loss at 13%.

CT reconstruction of an unusual chronic posttraumatic aneurysm of the thoracic aorta.

Chronic traumatic aneurysm of the thoracic aorta is an unusual occurrence. Previously, arteriography was performed on all patients seen in our institution with this entity to allow confirmation of the diagnosis and anatomic delineation for operation. A case of chronic traumatic aneurysm of the distal descending aorta discovered on a routine chest roentgenogram and evaluated with chest computed tomographic scanning with three-dimensional reconstruction is presented. It is our belief that not all thoracic aneurysms require arteriography, and improved methods of computed tomographic scanning allow adequate diagnosis and anatomic delineation with decreased morbidity and cost.

A technique for flow-enhanced magnetic resonance angiography of the lower extremities.

A two-dimensional, flow-enhanced gradient echo pulse sequence for nuclear magnetic resonance angiography is described. It employs interleaved, presaturated slices to acquire data efficiently on imagers which favor interleaved acquisition over sequential acquisition for multislice imaging. It is useful on any imagers when the effective TR is extended to enhance the sensitivity to slow flow. The technique was applied to the region from aortic bifurcation to the iliac bifurcations of three normal volunteers. The right and left common iliac arteries and veins, the separation of the external and internal iliac arteries, and secondary branches were clearly depicted.

Imaging assessment of sacroiliac screw placement relative to the neuroforamen.

STUDY DESIGN: Twenty-four cannulated sacroiliac screws were placed bilaterally into 12 cadaveric pelvi (12 titanium screws and 12 stainless-steel screws) and were imaged using conventional and multiplanar reconstructed computed tomography. OBJECTIVES: To determine whether sacroiliac screw position assessment relative to the neuroforamen is enhanced by: 1) computed tomography using multiplanar reconstructions and 2) the use of titanium screws rather than stainless-steel screws. SUMMARY OF BACKGROUND DATA: To the authors' knowledge, there have been no prior studies demonstrating the accuracy of multiplanar computed tomography compared with that of conventional (axial) tomography in determining the position of sacroiliac screws relative to the neuroforamen. Although titanium screws have been shown to have less scatter than stainless-steel screws, the effect of alloy composition on the radiographic accuracy of interpreting the screw position relative to the sacral neuroforamen is unknown. METHODS: Screws were deliberately placed into: position A, in which the screw did not violate the neuroforamen; position B, in which the threads of the screw came within 3 mm of the neuroforamen; and position C, in which the screw clearly was nearly centered in the neuroforamen. The degrees of accuracy in assessing screw position relative to the neuroforamen using conventional (axial) images and using multiplanar reconstructed images were compared. RESULTS: The axial images were accurate in determining screw position relative to the neuroforamen in 50% of cases in which titanium screws were used and in 42% of cases in which stainless-steel screws were used. The corresponding values for multiplanar reconstructions were 92% for cases in which titanium screws were used and 67% for cases in which stainless-steel screws were used. The accuracy of multiplanar reconstructions was statistically better than that of axial images (P < 0.05). Metallic scatter was increased in stainless-steel screws. CONCLUSIONS: The results of this study suggest that the use of computed tomography with multiplanar reconstruction improves accuracy in determining sacroiliac screw position relative to the neuroforamen. The assessment of screw position may be facilitated using titanium screws.

Changes in intervertebral disc cross-sectional area with bed rest and space flight.

STUDY DESIGN: We measured the cross-sectional area of the intervertebral discs of normal volunteers after an overnight rest; before, during, and after 5 or 17 weeks of bed rest; and before and after 8 days of weightlessness. OBJECTIVES: This study sought to determine the degree of expansion of the lumbar discs resulting from bed rest and space flight. SUMMARY OF BACKGROUND DATA: Weightlessness and bed rest, an analog for weightlessness, reduce the mechanical loading on the musculoskeletal system. When unloaded, intervertebral discs will expand, increasing the nutritional diffusion distance and altering the mechanical properties of the spine. METHODS: Magnetic resonance imaging was used to measure the cross-sectional area and transverse relaxation time (T2) of the intervertebral discs. RESULTS: Overnight or longer bed rest causes expansion of the disc area, which reaches an equilibrium value of about 22% (range 10-40%) above baseline within 4 days. Increases in disc area were associated with modest increases in disc T2. During bed rest, disc height increased approximately 1 mm, about one-half of previous estimates based on body height measurements. After 5 weeks of bed rest, disc area returned to baseline within a few days of ambulation, whereas after 17 weeks, disc area remained above baseline 6 weeks after reambulation. After 8 days of weightlessness, T2, disc area, and lumbar length were not significantly different from baseline values 24 hours after landing. CONCLUSIONS: Significant adaptive changes in the intervertebral discs can be expected during weightlessness. These changes, which are rapidly reversible after short-duration flights, may be an important factor during and after long-duration missions.

Regional muscle loss after short duration spaceflight.

BACKGROUND: Muscle strength and limb girth measurements during Skylab and Apollo missions suggested that loss of muscle mass may occur as a result of spaceflight. Extended duration spaceflight is important for the economical and practical use of space. The loss of muscle mass during spaceflight is a medical concern for long duration flights to the planets or extended stays aboard space stations. Understanding the extent and temporal relationships of muscle loss is important for the development of effective spaceflight countermeasures. HYPOTHESIS: We hypothesized that significant and measurable changes in muscle volume would occur in Shuttle crewmembers following 8 d of weightlessness. METHODS: MRI was used to obtain the muscle volumes of the calf, thigh and lower back before and after the STS-47 Shuttle mission. RESULTS: Statistical analyses demonstrated that the soleus-gastrocnemius (-6.3%), anterior calf (-3.9%), hamstrings (-8.3%), quadriceps (-6.0%) and intrinsic back (-10.3%) muscles were decreased, p < 0.05, compared to baseline, 24 h after landing. At 2 weeks post recovery, the hamstrings and intrinsic lower back muscles were still below baseline, p < 0.05. CONCLUSIONS: These results demonstrate that even short duration spaceflight can result in significant muscle atrophy.

A comparative study of the hovering efficiency of flapping and revolving wings.

Direct numerical simulations are used to explore the hovering performance and efficiency for hawkmoth-inspired flapping and revolving wings at Reynolds (Re) numbers varying from 50 to 4800. This range covers the gamut from small (fruit fly size) to large (hawkmoth size) flying insects and is also relevant to the design of micro- and nano-aerial vehicles. The flapping wing configuration chosen here corresponds to a hovering hawkmoth and the model is derived from high-speed videogrammetry of this insect. The revolving wing configuration also employs the wings of the hawkmoth but these are arranged in a dual-blade configuration typical of helicopters. Flow for both of these configurations is simulated over the range of Reynolds numbers of interest and the aerodynamic performance of the two compared. The comparison of these two seemingly different configurations raises issues regarding the appropriateness of various performance metrics and even characteristic scales; these are also addressed in the current study. Finally, the difference in the performance between the two is correlated with the flow physics of the two configurations. The study indicates that viscous forces dominate the aerodynamic power expenditure of the revolving wing to a degree not observed for the flapping wing. Consequently, the lift-to-power metric of the revolving wing declines rapidly with decreasing Reynolds numbers resulting in a hovering performance that is at least a factor of 2 lower than the flapping wing at Reynolds numbers less than about 100.

The significance of moment-of-inertia variation in flight manoeuvres of butterflies.

The objective of this study is to understand the role that changes in body moment of inertia might play during flight manoeuvres of insects. High-speed, high-resolution videogrammetry is used to quantify the trajectory and body conformation of Painted Lady butterflies during flight manoeuvres; the 3D kinematics of the centre of masses of the various body parts of the insect is determined experimentally. Measurements of the mass properties of the insect are used to parameterize a simple flight dynamics model of the butterfly. Even though the mass of the flapping wings is small compared to the total mass of the insect, these experiments and subsequent analysis indicate that changes in moment of inertia during flight are large enough to influence the manoeuvres of these insects.

Low speed maneuvering flight of the rose-breasted cockatoo (Eolophus roseicapillus). I. Kinematic and neuromuscular control of turning.

Maneuvering flight has long been recognized as an important component of the natural behavior of many bird species, but has been the subject of little experimental work. Here we examine the kinematics and neuromuscular control of turning flight in the rose-breasted cockatoo Eolophus roseicapillus (N=6), testing predictions of maneuvering flight and control based on aerodynamic theory and prior kinematic and neuromuscular studies. Six cockatoos were trained to navigate between two perches placed in an L-shaped flight corridor, making a 90 degrees turn midway through each flight. Flights were recorded with three synchronized high-speed video cameras placed outside the corridor, allowing a three-dimensional reconstruction of wing and body kinematics through the turn. We simultaneously collected electromyography recordings from bilateral implants in the pectoralis, supracoracoideus, biceps brachii and extensor metacarpi radialis muscles. The cockatoos maneuvered using flapping, banked turns with an average turn radius of 0.92 m. The mean rate of change in heading during a complete wingbeat varied through the turn and was significantly correlated to roll angle at mid-downstroke. Changes in roll angle were found to include both within-wingbeat and among-wingbeat components that bear no direct relationship to one another. Within-wingbeat changes in roll were dominated by the inertial effects while among-wingbeat changes in roll were likely the result of both inertial and aerodynamic effects.