Kyle R. Eberlin

Intestinal alkaline phosphatase is a gut mucosal defense factor maintained by enteral nutrition.

Under conditions of starvation and disease, the gut barrier becomes impaired, and trophic feeding to prevent gut mucosal atrophy has become a standard treatment of critically ill patients. However, the mechanisms responsible for the beneficial effects of enteral nutrition have remained a mystery. Using in vitro and in vivo models, we demonstrate that the brush–border enzyme, intestinal alkaline phosphatase (IAP), has the ability to detoxify lipopolysaccharide and prevent bacterial invasion across the gut mucosal barrier. IAP expression and function are lost with starvation and maintained by enteral feeding. It is likely that the IAP silencing that occurs during starvation is a key component of the gut mucosal barrier dysfunction seen in critically ill patients.

Quality Assurance Guidelines for Surgical Outreach Programs: A 20-Year Experience

Numerous American volunteer organizations travel throughout the developing world, providing surgical services to those in need. Medical staff who undertake such missions must contend with the realities inherent to providing healthcare abroad. Inadequate medical facilities and equipment, coupled with a short mission duration and the lack of substantial integration with the local medical community, greatly increase the risk of unnecessary medical complications. At present, there is no definitive set of quality assurance guidelines for the surgical outreach community. This report draws on 20 years of outreach experience to recommend a set of quality assurance guidelines for surgical outreach missions.

Ischemic Preconditioning of Skeletal Muscle Mitigates Remote Injury and Mortality

BACKGROUND Ischemic preconditioning (IPC) mitigates ischemia-reperfusion (I/R) injury in experimental models. However, the clinical significance of this protection has been unclear and a mortality reduction has not been previously reported in noncardiac models. This study examined the local and remote protection afforded by skeletal muscle IPC and sought to determine the significance of this protection on mortality. METHODS Mice subjected to 2 h hindlimb ischemia/24 h reperfusion (standard I/R injury) were compared with those undergoing a regimen of two 20-min cycles of IPC followed by standard I/R injury. Local injury was assessed via gastrocnemius histology, and remote injury was evaluated via intestinal histology and pulmonary neutrophil infiltration (n = 7). Mortality was compared in parallel groups for 1 week (n = 6). Groups were analyzed using an unpaired Students t-test for gastrocnemius and pulmonary injury, and a Mann-Whitney rank sum test for intestinal injury. Mortality differences were interpreted through a hazard ratio. RESULTS Significant protection was observed in preconditioned animals. There was a 35% local injury reduction in skeletal muscle (71.2% versus 46.0%, P < 0.01), a 50% reduction in remote intestinal injury (2.3 versus 1.1, P < 0.01), and a 43% reduction in remote pulmonary injury (14.9 versus 8.5, P < 0.01) compared with standard injury controls. Preconditioned animals were also significantly protected from mortality, demonstrating a 66.7% survival at 1 wk compared with 0% survival after standard injury alone (hazard ratio 0.20, 95% CI: 0.02-0.59). CONCLUSIONS We have developed a murine model of IPC that demonstrates local and remote protection against I/R injury, and exhibits significant mortality reduction. This model demonstrates the powerful effect of IPC on local and remote tissues and will facilitate further study of potential mechanisms and therapies.

A Novel Murine Island Skin Flap for Ischemic Preconditioning

BACKGROUND Ischemia reperfusion injury is a well-known phenomenon affecting skin flap viability. One method to improve flap viability is ischemic preconditioning. Previous murine flap models used random flaps. We developed a single pedicle island skin flap which allows us to create true ischemia by clamping the single pedicle. Our first aim was to describe a novel murine skin flap model with a definable, reproducible injury. Our second aim was to test the usefulness of this model by demonstrating mitigation of injury via ischemic preconditioning. MATERIALS AND METHODS Dorsal lateral thoracic artery pedicle island skin flaps (3.5 x 1.5 cm) were elevated in 39 male C57/BL6 mice: a Control group (n = 7), 10 h of ischemia (n = 21), and Preconditioning (2 cycles of 20 min ischemia: 20 minutes reperfusion) + 10-h ischemia (n = 11). After flap elevation, a silicon sheet barrier was placed. The axial pedicles were occluded, and the flaps were inset with 6-0 prolene. In all mice, ischemia was followed by 1 wk of reperfusion. At 1 wk, percent necrosis was measured and an analysis of variance was performed. RESULTS The percent of flap necrosis was 1.1% +/- 1.11% in controls. Animals that were subjected to 10 h of ischemia developed 33.14% +/- 7.23% necrosis. Preconditioned animals that underwent 10 h of ischemia demonstrated a 43% reduction in necrosis (18.82% +/- 5.68%). There was a statistically significant difference among all groups (P < or = 0.001). CONCLUSION Rat models have been the standard for skin flap experiments. We have developed a novel murine single pedicle island skin flap model with reproducible injury. This model has numerous advantages, including ease of handling, low cost, appropriateness for biomedical studies, and the availability of genetically altered animals. We also confirmed this models usefulness in a study of mitigation of ischemia reperfusion injury through ischemic preconditioning.

The overutilization of resources in patients with acute upper extremity trauma and infection.

PURPOSE To compare patients with acute upper extremity injuries and infections presenting initially to the emergency department with patients transferred from outside institutions, and to evaluate triage guidelines for the appropriate transfer of these patients. METHODS We reviewed the records of 1,172 consecutive patients with acute upper extremity injuries or infections presenting to 2 level 1 trauma centers over 3-month periods. We analyzed demographics, transfer details, injury characteristics, intervention received, follow-up, and complications. Triage guidelines were established by a board of academic upper extremity and emergency physicians and retrospectively applied to patient data. RESULTS Of 1,172 patients, 155 (13%) arrived via transfer from outside facilities. Transferred patients had more complex injuries by our guidelines, but many did not require level 1 emergent care. The receiving emergency department discharged 26% of the transferred patients without upper extremity specialist evaluation, and 24% of the transferred patients received no procedural intervention at any point. Only 10% went to the operating room emergently. Implementing our guidelines for appropriate triage, we found that 53% of transfers did not require emergent transfer to a level 1 facility. These nonemergent transfers spent an average of 15.2 hours from the time of initial evaluation at the outside facility to discharge from the level 1 emergency department, compared with 3.1 hours in patients who arrived primarily. Retrospectively, our triage guidelines had a 2% undertriage rate and a 3% overtriage rate. CONCLUSIONS Over half of the patients transferred with upper extremity injuries and infections for specialized evaluation may be transferred unnecessarily. Guidelines for the care and transfer of patients with acute upper extremity injuries or infections may lead to better use of resources. TYPE OF STUDY/LEVEL OF EVIDENCE Prognostic III.

Sequential limb ischemia demonstrates remote postconditioning protection of murine skeletal muscle.

Background: Ischemic postconditioning, the process of exposing tissues to brief cycles of ischemia-reperfusion after critical ischemia, can mitigate local ischemia-reperfusion injury. Remote protection of skeletal muscle has never been demonstrated in postconditioning models of ischemia-reperfusion injury. Methods: Mice were subjected to 2 hours of ipsilateral hind limb ischemia followed by reperfusion. Contralateral limb ischemia was subsequently induced for 2 hours after either 0 (n = 6), 20 (n = 6), or 120 (n = 5) minutes of ipsilateral limb reperfusion. These groups were compared with animals subjected to bilateral simultaneous injury (n = 8) and sham animals that did not undergo ischemia (n = 6). The gastrocnemius muscles were harvested for histologic evaluation, and injury was recorded as the percentage of injured fibers. Results: The first limbs undergoing injury in the 20-minute interval group had a 59 percent injury reduction compared with contralateral limbs (16.0 ± 2.4 percent versus 39.5 ± 6.5 percent) after 24 hours of reperfusion and 62 percent reduction after 48 hours (24.4 ± 3.0 percent versus 63.6 ± 5.5 percent). In animals with no interval or a 120-minute interval between the onset of limb ischemia, there was no significant difference in injury between hind limbs. The injury in these groups was similar to that in hind limbs subjected to simultaneous bilateral ischemia. Conclusions: A 20-minute reperfusion interval between hind limb ischemia significantly protects against injury in the initially ischemic limb, while similar injury is observed with simultaneous ischemia or an interval of 120 minutes. This study demonstrates remote postconditioning of skeletal muscle and may lead to the development of post hoc therapies.

Combined use of infraorbital and external nasal nerve blocks for effective perioperative pain control during and after cleft lip repair.

Perioperative analgesia in patients undergoing cleft lip and palate repair is complicated by the risk of postoperative airway obstruction. We describe a technique of combined infraorbital and external nasal nerve blocks to reduce the need for opioid analgesia. Using this technique, we have successfully performed cleft lip repair under local anesthesia alone, without general anesthesia or intravenous sedation, in adolescents and adults. In children, this technique can reduce the need for postoperative opioids. We describe this novel analgesic approach to decrease opioid requirements and minimize perioperative risk.

High-impact articles in hand surgery

BackgroundThere have been few attempts to identify classic papers within the hand surgery literature. This study used citation analysis to identify and characterize the top 50 highly cited hand surgery articles published in six peer-reviewed journals.MethodsThe 50 most highly cited hand surgery articles were identified in the Journal of Bone and Joint Surgery (JBJS) American, JBJS British, Plastic and Reconstructive Surgery, Journal of Hand Surgery (JHS) American, JHS British/European, and Hand. Articles were evaluated for citations per year, surgical/anatomical topic, and type of study. Clinical studies were further sub-categorized by level of evidence. The distribution of topics was compared with all indexed hand surgery articles. The educational relevance was assessed via comparison with lists of “classic” papers.ResultsThe most common subjects were distal radius fracture, carpal tunnel syndrome, and flexor tendon repair. There was moderate correlation between the distribution of these topics and all indexed hand surgery articles (rho = 0.71). There were 31 clinical studies, of which 16 were therapeutic, ten were prognostic, and five were diagnostic. These articles assessed the outcomes of an intervention, described an anatomical/functional observation, introduced an innovation, presented a discovery/classification, or validated a questionnaire. There were only three randomized trials. Using citations per year to control for the influence of time since publication, 36 articles were consistently highly cited. Twenty-three articles were on Stern’s Selected Readings in Hand Surgery, considered important in education.ConclusionsThe top 50 highly cited articles in hand surgery reflect the most common clinical, scientific, and educational efforts of the field.

Improved Survival of Murine Island Skin Flaps by Prevention of Reperfusion Injury

Background: Studies have demonstrated that blocking a single specificity of self-reactive immunoglobulin M with a 12–amino acid peptide mimic of the antigen of immunoglobulin M can attenuate murine intestinal and skeletal muscle injury following ischemia and reperfusion. The aim of this study was to ascertain whether peptide (P8) had protective effects in an axial island skin flap model, where tissue loss is attributed to ischemia-reperfusion injury. Methods: Dorsal lateral thoracic artery island skin flaps (3.5 × 1.5 cm) were elevated in 82 male C57BL/6 mice and rendered ischemic for 10 hours by placing a 7-mm microclamp on the vascular pedicle followed by 7 days of reperfusion. Group I (n = 7), the sham group, had no clamp placed. Group II (n = 21) had clamp placement but no other treatment. Thirty minutes before clamp placement, group III (n = 18) received 0.25 cc of saline intravenously, group IV (n = 18) received 25 &mgr;g/0.25 cc P8 peptide, and group V (n = 7) received 25 &mgr;g/0.25 cc random 12-mer peptide. Animals in group VI (n = 11) underwent two cycles of 20 minutes of ischemic preconditioning before 10 hours of ischemia. After 1 week of reperfusion, percent necrosis was measured and results were compared using analysis of variance and an unpaired t test. Results: In animals treated with P8 peptide, flap necrosis was 14.61 ± 2.77 percent. This represents a statistically significant, 56 percent reduction in flap necrosis compared with controls (p < 0.001). Conclusion: These data demonstrate that prevention of ischemia-reperfusion injury with P8 peptide produces a significant reduction in necrosis of treated flaps.

Intraoperative Physical Examination for Diagnosis of Interosseous Ligament Rupture—Cadaveric Study

PURPOSE To study the intraobserver and interobserver reliability of the diagnosis of interosseous ligament (IOL) rupture in a cadaver model. METHODS On 12 fresh frozen cadavers, radial heads were cut using an identical incision and osteotomy. After randomization, the soft tissues of the limbs were divided into 4 groups: both IOL and triangular fibrocartilage (TFCC) intact; IOL disruption but TFCC intact; both IOL and TFCC divided; and IOL intact but TFCC divided. All incisions had identical suturing. After standard instruction and demonstration of radius pull-push and radius lateral pull tests, 10 physician evaluators with different levels of experience examined the cadaver limbs in a standardized way (elbow at 90° with the forearm held in both supination and pronation) and were asked to classify them into one of the 4 groups. Next, the same examiners were asked to re-examine the limbs after randomly changing the order of examination. RESULTS The interobserver reliability of agreement for the diagnosis of IOL injury (groups 2 and 3) was fair in both rounds of examination and the intraobserver reliability was moderate. The intra- and interobserver reliabilities of agreement for the 4 groups of injuries among the examiners were fair in both rounds of examination. The sensitivity, specificity, accuracy, positive, and negative predictive values were all around 70%. The likelihood of a positive test corresponding with the presence of IOL rupture (positive likelihood ratio) was 2.2. The likelihood of a negative test correctly diagnosing an intact IOL was 0.40. CONCLUSIONS In cadavers, intraoperative tests had fair reliability and 70% accuracy for the diagnosis of IOL rupture using the push-pull and lateral pull maneuvers. The level of experience did not have any effect on the correct diagnosis of intact versus disrupted IOL. CLINICAL RELEVANCE Although not common, some failure of surgeries for traumatic elbow fracture-dislocations is because of failure in timely diagnosis of IOL disruption.