Comparison of wound strength, histologic, and aesthetic outcomes after microsurgical versus conventional skin closure in a rat model.

The purpose of this study was to compare the healing, strength, and cosmetic outcome of linear incisions after repair with the naked eye, surgical loupes, or a surgical microscope. Two parallel incisions were made on the dorsal skin of Sprague-Dawley rats (n = 36) and the rats randomized into four groups. A single surgeon repaired the incisions using 5-0 poliglecaprone in a running subcuticular pattern using the naked eye (Group I), surgical loupes with 2.5× magnification (Group II), surgical microscope with 5-10× magnification (Group III), and 6-0 poliglecaprone with a surgical microscope (Group IV). Rats were sacrificed at 1, 3, and 6 weeks. At each time point, the tensile strength of each closure was assessed. Macroscopic outcomes were evaluated using the Vancouver Scar Scale (VSS) and histology assessed by a blinded observer. Microscope closure took significantly longer than closure with the naked eye (p < 0.05). There was no significant difference in tensile strength or VSS ratings between the closure methods at any of the time points. On histopathologic analysis, there were a greater number of inflammatory cells and fibroblasts in the 6-0 microscope closure group versus the naked eye closure group at week 3 (p ≤ 0.05). In conclusion, wound repair under magnification did not yield a significant difference in cosmesis or wound tensile strength, but did increase operative time. Moreover, there was a trend toward increased inflammation with microscope-assisted closures, perhaps due to the increased suture burden.

Use of open and endovascular surgical techniques to manage vascular injuries in the trauma setting: A review of the American Association for the Surgery of Trauma PROspective Observational Vascular Injury Trial registry.

BACKGROUND: Vascular trauma data have been submitted to the American Association for the Surgery of Trauma PROspective Observational Vascular Injury Trial (PROOVIT) database since 2013. We present data to describe current use of endovascular surgery in vascular trauma. METHODS: Registry data from March 2013 to December 2016 were reviewed. All trauma patients who had an injury to a named artery, except the forearm and lower leg, were included. Arteries were grouped into anatomic regions and by compressible and noncompressible region for analysis. This review focused on patients with noncompressible transection, partial transection, or flow-limiting defect injuries. Bivariate and multivariate analyses were used to assess the relationships between study variables. RESULTS: One thousand one hundred forty-three patients from 22 institutions were included. Median age was 32 years (interquartile range, 23-48) and 76% (n = 871) were male. Mechanisms of injury were 49% (n = 561) blunt, 41% (n = 464) penetrating, and 1.8% (n = 21) of mixed aetiology. Gunshot wounds accounted for 73% (n = 341) of all penetrating injuries. Endovascular techniques were used least often in limb trauma and most commonly in patients with blunt injuries to more than one region. Penetrating wounds to any region were preferentially treated with open surgery (74%, n = 341/459). The most common indication for endovascular treatment was blunt noncompressible torso injuries. These patients had higher Injury Severity Scores and longer associated hospital stays, but required less packed red blood cells, and had lower in hospital mortality than those treated with open surgery. On multivariate analysis, admission low hemoglobin concentration and abdominal injury were independent predictors of mortality. CONCLUSION: Our review of PROOVIT registry data demonstrates a high utilization of endovascular therapy among severely injured blunt trauma patients primarily with noncompressible torso hemorrhage. This is associated with a decreased need for blood transfusion and improved survival despite longer length of stay. LEVEL OF EVIDENCE: Therapeutic/care management, level III.

Pharmacokinetics of sternal intraossesous atropine administration in normovolemic and hypovolemic swine.

OBJECTIVE: Characterize and compare the pharmacokinetics of atropine administered via the sternal intraosseous (IO) route in a normovolemic and hypovolemic swine model. DESIGN: Prospective, experimental study. SETTING: Vivarium. SUBJECTS: Yorkshire-cross swine (N = 12). INTERVENTION: Atropine was administered via the sternal IO route to normovolemic and hypovolemic swine. Blood samples were drawn at regular intervals after atropine administration and analyzed for plasma atropine concentration. Pharmacokinetic parameters were obtained from modeling the plasma concentrations. MAIN OUTCOME MEASUREMENTS: Pharmacokinetic parameters, maximum concentration (Cmax), and time to maximum concentration (Tmax). RESULTS: The normovolemic and hypovolemic models reached peak plasma concentration immediately and had a very rapid distribution phase with no apparent absorption phase for the IO groups. The hypovolemic group had slower clearance and longer half-life compared to the normovolemic group. CONCLUSION: The sternal IO route is an effective method of administering atropine and is comparable to the previously reported tibial IO and intravenous data even under conditions of significant hemorrhage.

Assessment of carprofen and buprenorphine on recovery of mice after surgical removal of the mammary fat pad.

The purpose of this study was to determine the level of pain elicited by mammary fat pad removal surgery and the effects of postoperative analgesics on recovery. Female FVB mice were anesthetized, and mammary fat pad removal was performed. After surgery, mice received carprofen, buprenorphine, a combination of carprofen and buprenorphine, or saline treatment. Additional mice received anesthesia but no surgery or treatment. Food and water intake, body weight, wheel running activity, and a visual assessment score were recorded daily for 4 d after surgery and compared with presurgical findings. Corticosterone metabolites in fecal samples were analyzed at 12 and 24 h postsurgically and compared with baseline values. All surgical groups had significantly decreased food intake at 24 h, with a return to baseline by 48 h. The combination treatment resulted in a significantly decreased water intake and body weight at 24 h. All surgical groups had significantly decreased wheel running activity at 24 h only. The visual assessment scores indicated mild pain for all surgical groups, with the buprenorphine treated mice showing the highest pain index scores, as compared with nonsurgical controls. Fecal corticosterone metabolite levels did not differ significantly between any of the groups or across time. The parameters used in this study did not indicate that administration of these analgesic regimens improved recovery as compared with that of saline-treated mice. Care should be taken when using visual assessment scores to evaluate pain in mice, given that analgesics may have side effects that inadvertently elevate the score.

Dextran polymer hemostatic dressing improves survival in liver injury model.

BACKGROUND: Improvements in early hemorrhage control could result in more favorable outcomes. Several advanced hemostatic dressings are available; however, none meets the ideal characteristics defined by the United States Army. We studied the effects of a new dextran polymer hemostatic dressing on survival, blood loss, and blood pressure in a swine model of severe liver injury. METHODS: We randomized 12 Yorkshire swine to treatment with either standard laparotomy pads or laparotomy pads coated with a dextran polymer (Bloxx). These dressings are visually identical, and investigators were not informed of the dressing assignment. We transected the left medial lobe of the liver in the anesthetized swine with a large knife, applied dressings immediately, and held pressure for 7 min. The animals received a weight-based maintenance crystalloid infusion without further resuscitation. Endpoints were blood loss, blood pressure, early mortality (120 min), and tissue histology. RESULTS: Baseline and pre-injury characteristics were similar between all animals. Three of six animals in the control group survived for 2 h while all six animals treated with Bloxx survived (P=0.05). Similarly, animals in the Bloxx group experienced less blood loss (10.4+/-8.8 mL/kg versus 28.3+/-13.0 mL/kg, P=0.025) and higher post-injury blood pressure than the control group. Bloxx was not associated with macroscopic or microscopic tissue damage. CONCLUSIONS: Bloxx is superior to standard laparotomy sponges in this model of lethal liver injury. Further study of this dressing is warranted to determine its potential for use in civilian and military trauma.

Aircraft and related factors in crashes involving spatial disorientation: 15 years of U.S. Air Force data.

INTRODUCTION: Previous studies have determined that spatial disorientation (SD) causes 0.5-23% of aircraft crashes, but SD-related crash and fatality rates in different aircraft types have not been systematically studied. METHODS: SD crashes for the fiscal years 1990 to 2004 and aircraft sortie numbers for all U.S. Air Force (USAF) aircraft were obtained from the USAF Safety Center. Contingency table analysis and Chi-squared tests were used to evaluate differences in SD rates. RESULTS: SD accounted for 11% of USAF crashes with an overall rate of 2.9 per million sorties and a crash fatality rate of 69%. The SD rate was higher in fighter/attack aircraft and helicopters than in training and transport aircraft. The risk of SD was increased at night with 23% of night crashes being caused by SD. But the SD rate and crash fatality rate were not higher in single-crewmember aircraft. DISCUSSION: SD risk is significantly increased in helicopters and fighter/attack aircraft and at night. The data suggest that a second crewmember does not protect against SD. Further study of specific SD scenarios could lead to focused interventions for SD prevention.

Analysis of mission and aircraft factors in G-induced loss of consciousness in the USAF: 1982-2002.

INTRODUCTION: Previous studies have used questionnaires to evaluate G-LOC incident rates in different aircraft types, but no studies of G-LOC-related incident, crash, and fatality rates in different aircraft types were found in a search of the literature. METHODS: G-LOC events (including both incidents and crashes) for the fiscal years 1982 to 2002 were obtained from the USAF Safety Center. Aircraft sortie numbers were obtained for all aircraft that had a G-LOC event reported. Contingency table analysis and Chi-squared tests were used to evaluate differences in G-LOC rates. RESULTS: Overall 559 G-LOC events occurred for a rate of 25.9 per million sorties (PMS), but event rates differed by almost two orders of magnitude between aircraft categories, being highest in basic training aircraft, intermediate in single crewmember fighters, and lowest in other aircraft types (p < 0.001). The proportion of events resulting in crashes was 30% in single-crewmember aircraft compared with 0.6% in trainers and other two-crewmember aircraft (p < 0.001). All of the crashes and fatalities occurred in aircraft occupied at the time by only a single crewmember. The crash fatality rate was 100% in attack aircraft, 73% in single-crewmember fighters, and zero in basic trainers (p < 0.05). The F-15 and F-16 aircraft did not have higher G-LOC rates than other single-seat fighters. DISCUSSION: The data suggest that both crew complement and mission play a role in determining G-LOC rates. The data also suggest that G-LOC in an aircraft with a ground attack mission is more likely to result in a fatality.

Preventing G-induced loss of consciousness: 20 years of operational experience.

INTRODUCTION: Although anecdotal reports of G-induced loss of consciousness (G-LOC) in military aviation date back to before 1920, regular reporting did not begin until 1982. The effectiveness in the operational setting of G-LOC preventive measures, such as positive pressure breathing for G protection (PBG), has not been studied. METHODS: We use the term "crash" to represent an event where the aircraft was destroyed and "incident" to define those events where the crew reported a G-LOC episode and the aircraft was not damaged. Data on G-LOC crashes, incidents, and aircraft sorties (number of take-offs) were obtained from the USAF Safety Center database for FY 82-01. RESULTS: During FY 82-01, there were 29 G-LOC crashes while those aircraft at risk of G-LOC crashes flew a total of 13,959,816 sorties. Poisson regression showed a non-significant decrease in crashes with an incidence rate ratio (IRR) of 0.096 (CI 0.89-1.03) (4% per yr). G-LOC crashes decreased from 4.4 per million flight sorties (PMFS) to 1.6 after the implementation of anti-G-LOC training programs beginning in 1985. However, G-LOC crashes remained unchanged after implementation of PBG in 1995. In contrast, incidents showed an IRR of 1.04 (CI 1.02-1.06) for G-LOC incidents, an estimated increase of 5% per yr. DISCUSSION: The physical/mechanical limitations of PBG, risk homeostasis, and the possibility that G-LOC rates have reached their asymptotic minimum are all discussed as possible explanations for the failure of PBG to decrease G-LOC crashes.