Amelia S. Munsterman

Comparison of direct and indirect methods of intra-abdominal pressure measurement in normal horses.

OBJECTIVES To develop a direct method for measuring intra-abdominal pressures in the standing horse, identify a reference interval for direct intra-abdominal pressures, compare these pressures to indirect intra-abdominal pressures measured from the bladder, and determine the optimal bladder infusion volume for indirect pressure measurement. DESIGN Prospective, experimental study. SETTING A university-based equine research facility. ANIMALS Ten healthy adult horses, 5 males and 5 females. INTERVENTIONS Direct intra-abdominal pressures were measured through an intraperitoneal cannula and zeroed at the height midway between the height of the tuber ishii and point of the shoulder. Indirect measurements of intra-abdominal pressure were performed by measuring intravesicular pressures through a transurethral catheter zeroed at the tuber ishii. MEASUREMENTS AND MAIN RESULTS Direct pressure measurements obtained in the standing horse were subatmospheric (mean, -1.80 cm H(2)O; SD, 1.61 cm H(2)O; 95% CI, -2.80 to -0.80) and were shown to decrease as the horses weight increased (Pearsons r=-0.67, P=0.04), with no effect of head position (P=0.15). Mean baseline indirect pressure measurements (mean, -8.63 cm H(2)O; SD, 4.37 cm H(2)O; 95% CI, -13.05 to -4.21) were significantly different from the pressures measured directly from the abdomen (P<0.001). Indirect pressure measurements were noted to increase with increasing volumes infused into the bladder, and were statistically different at a volume of 100 mL (P=0.004). There was low to moderate correlation between direct and indirect pressure measurements of intra-abdominal pressure over a range of fluid volumes infused into the bladder (Pearsons correlation range -0.38 to 0.58). CONCLUSION Pressures measured directly in the standing horse were subatmospheric, and increased as the horses weight increased. Indirect pressures measured were altered by increasing volumes infused in the bladder. There was no significant correlation between the 2 methods of intra-abdominal pressure measurement.

Surgical technique and short-term outcome for experimental laparoscopic closure of the epiploic foramen in 6 horses.

Objective To describe a laparoscopic technique for, and short-term outcome after, closure of the epiploic foramen (EF) in horses. Study Design Descriptive, experimental study. Animals Healthy, adult horses (n = 6). Methods Laparoscopic portals to approach the EF were identified in standing horses. Under laparoscopic observation, the gastropancreatic fold and right lobe of the pancreas were grasped with Babcock forceps and secured to the caudate hepatic lobe using helical titanium coils to obliterate the EF. Surgical procedure time and intra- and postoperative complications were recorded. Serial analysis of select serum enzymes was used as an indication of involvement of the pancreas and liver. Closure was reevaluated at 4 weeks using repeat laparoscopy, and necropsy was performed immediately after. Results At initial surgery, EF closure was successful in all 6 horses; median surgical time was 40.5 minutes (range, 22–110 minutes). Serum gamma-glutamyl transferase (GGT) and sorbitol dehydrogenase (SDH) were not significantly altered by the surgical procedure; however, aspartate aminotransferase (AST) and amylase (AMY) were transiently increased. At repeat laparoscopic reevaluation, closure was complete in 5 horses, with partial closure of the EF observed in 1 horse. No complications related to the procedure were noted during or after surgery in any horse. Conclusions EF closure in the standing horse can be accomplished without complications to the surrounding organs and vessels.OBJECTIVE To describe a laparoscopic technique for, and short-term outcome after, closure of the epiploic foramen (EF) in horses. STUDY DESIGN Descriptive, experimental study. ANIMALS Healthy, adult horses (n = 6). METHODS Laparoscopic portals to approach the EF were identified in standing horses. Under laparoscopic observation, the gastropancreatic fold and right lobe of the pancreas were grasped with Babcock forceps and secured to the caudate hepatic lobe using helical titanium coils to obliterate the EF. Surgical procedure time and intra- and postoperative complications were recorded. Serial analysis of select serum enzymes was used as an indication of involvement of the pancreas and liver. Closure was reevaluated at 4 weeks using repeat laparoscopy, and necropsy was performed immediately after. RESULTS At initial surgery, EF closure was successful in all 6 horses; median surgical time was 40.5 minutes (range, 22-110 minutes). Serum gamma-glutamyl transferase (GGT) and sorbitol dehydrogenase (SDH) were not significantly altered by the surgical procedure; however, aspartate aminotransferase (AST) and amylase (AMY) were transiently increased. At repeat laparoscopic reevaluation, closure was complete in 5 horses, with partial closure of the EF observed in 1 horse. No complications related to the procedure were noted during or after surgery in any horse. CONCLUSIONS EF closure in the standing horse can be accomplished without complications to the surrounding organs and vessels.

Formalizing the definition of meta‐analysis in Molecular Ecology

Meta‐analysis, the statistical synthesis of pertinent literature to develop evidence‐based conclusions, is relatively new to the field of molecular ecology, with the first meta‐analysis published in the journal Molecular Ecology in 2003 (Slate & Phua 2003). The goal of this article is to formalize the definition of meta‐analysis for the authors, editors, reviewers and readers of Molecular Ecology by completing a review of the meta‐analyses previously published in this journal. We also provide a brief overview of the many components required for meta‐analysis with a more specific discussion of the issues related to the field of molecular ecology, including the use and statistical considerations of Wrights FST and its related analogues as effect sizes in meta‐analysis. We performed a literature review to identify articles published as ‘meta‐analyses’ in Molecular Ecology, which were then evaluated by at least two reviewers. We specifically targeted Molecular Ecology publications because as a flagship journal in this field, meta‐analyses published in Molecular Ecology have the potential to set the standard for meta‐analyses in other journals. We found that while many of these reviewed articles were strong meta‐analyses, others failed to follow standard meta‐analytical techniques. One of these unsatisfactory meta‐analyses was in fact a secondary analysis. Other studies attempted meta‐analyses but lacked the fundamental statistics that are considered necessary for an effective and powerful meta‐analysis. By drawing attention to the inconsistency of studies labelled as meta‐analyses, we emphasize the importance of understanding the components of traditional meta‐analyses to fully embrace the strengths of quantitative data synthesis in the field of molecular ecology.

Evaluation of gastric pressures as an indirect method for measurement of intraabdominal pressures in the horse.

OBJECTIVE To develop an indirect method for measurement of intraabdominal pressures in the standing horse using measurement of gastric pressures as a less invasive technique, and to compare this method with direct intraabdominal pressures obtained from the peritoneal cavity. DESIGN Prospective, experimental study. SETTING University-based equine research facility. ANIMALS Ten healthy adult horses, 7 geldings and 3 mares. INTERVENTIONS Gastric pressures were measured using a nasogastric tube with a U-tube manometry technique, while intraperitoneal pressures were measured with a peritoneal cannula. Measurements of intraabdominal pressure were obtained by both methods, simultaneously, and were evaluated using 5 increasing volumes of fluid infused into the stomach (0, 400, 1,000, 2,000, and 3,000 mL). Bias and agreement between the 2 methods were determined using Bland-Altman analysis and Lins concordance correlation coefficients. MEASUREMENTS AND MAIN RESULTS Mean gastric pressure was 14.44 ± 4.69 cm H(2)O and ranged from 0 to 25.8 cm H(2)O. Intraperitoneal pressure measurements were generally subatmospheric, and ranged from -6.6 to 3.1 cm H(2) O (mean ± SD, -1.59 ± 2.09 cm H(2)O). Measurements of intraperitoneal pressures were repeatable; however, intra- and interindividual variance was significantly larger for measurements of gastric pressures. The mean and relative bias for comparison between the 2 techniques was 15.9 ± 5.3 cm H(2)O and 244.3 ± 199.2%, respectively. The Lins concordance correlation coefficient between gastric and intraperitoneal pressures was -0.003 but this was not statistically significant (P=0.75). CONCLUSIONS There was no statistical concordance between measurements of intraabdominal pressure using gastric and intraperitoneal pressure measurement, indicating that gastric pressures cannot be substituted for intraperitoneal pressure measurement. Direct measurement of intraperitoneal pressures may be a more consistent method for comparison of intraabdominal pressures between horses, due to less variability within and between individuals.

In Vitro Evaluation of the Aberdeen Knot for Continuous Suture Patterns with Large Gauge Suture

OBJECTIVE To evaluate the strength, size, and holding capacity of the Aberdeen knot compared to surgeons and square knots using large gauge suture. STUDY DESIGN In vitro mechanical study. STUDY POPULATION Knotted suture. METHODS Aberdeen, surgeons, and square knots were tested using 2 and 3 USP polyglactin 910 and 2 USP polydioxanone under linear tension on a universal testing machine. Mode of failure and knot holding capacity (KHC) were recorded and relative knot security (RKS) was calculated as a percentage of KHC. Knot volume and weight were quantified by a digital micrometer and balance, respectively. Strength between number of throws, suture, suture size, and knot type were compared by ANOVA and post hoc testing. P≤.05 was considered significant. RESULTS Aberdeen knots had higher KHC and RKS than surgeons or square knots for all suture types and number of throws (P<.001). For all suture materials, none of the Aberdeen knots unraveled, but a portion of square and surgeons knots with <7 throws did unravel (P=.101). Aberdeen knots had a smaller volume and weight than both surgeons and square knots with equal numbers of throws (P<.001). The knot with the combined highest RKS and smallest size and weight was an Aberdeen knot with 4 throws using 3 USP polyglactin 910. CONCLUSION The Aberdeen knots were stronger, more secure, and smaller than surgeons and square knots for ending a continuous suture pattern. Clinically, the Aberdeen knot may be a useful alternative for completion of continuous patterns using large gauge suture, without sacrificing knot integrity.

Meta-Analysis of the Effects of Adhesion Barriers on Adhesion Formation in the Horse.

OBJECTIVE To determine the efficacy of adhesion barriers in horses using quantitative statistical analysis. STUDY DESIGN Meta-analytical review. METHODS A search using PubMed/MEDLINE and Google Scholar was performed, followed by secondary searches of veterinary trade journals, bibliographies of relevant articles, manufacturer websites, and technical reference guides. Randomized experimental trials in healthy horses were considered that included both a treatment and control group. The endpoint required was euthanasia or laparoscopy to identify adhesion formation. A meta-analysis was performed using a random effects model, with the effect size calculated as an odds ratio (OR) with 95% confidence intervals (CI). Statistical significance was set at P<.05. RESULTS Out of 354 peer reviewed publications that met the search criteria, a total of 9 relevant studies were identified and investigated the use of sodium carboxymethylcellulose (CMC) solutions, sodium hyaluronate/carboxymethylcellulose (HA/CMC) membranes, hyaluronate (HA), and fucoidan solutions. The odds of adhesions in horses treated with an adhesion barrier were significantly lower than untreated controls (OR=0.102; 95% CI [0.041, 0.254]; P<.001). When analyzed as subsets for each type of barrier, horses treated with HA/CMC membranes and CMC solutions had significant OR for fewer adhesions (OR=0.061; 95% CI [0.013, 0.292]; OR=0.119; 95% CI [0.034, 0.415], respectively; P<.001). CONCLUSION The meta-analysis demonstrated adhesion barriers provide a positive effect on the odds of adhesion formation. These results are tempered by the limitations of the study, including the small sample size and a bias towards publication of studies with only positive findings.

Biomechanical Testing of a Novel Tendon Implant Device for the Repair of Equine Flexor Tendon Lacerations

OBJECTIVE To compare in vitro strength and failure characteristics of a tendon implant against a 3 loop pulley suture pattern for equine superficial digital flexor tendon (SDFT) laceration repair. STUDY DESIGN Experimental. STUDY POPULATION Cadaveric equine forelimb SDFT (n = 16). METHODS One tendon of each of 8 pair of SDFT was randomly selected for repair with either the 3-loop pulley (3LP) suture pattern using 2 polydioxanone or with 4 stainless steel suture and anchor implants (SA). Ultimate load to failure, mode of failure, gap at failure, and load to 2 mm gap were obtained using a materials testing system synchronized with a high-speed camera. Statistical evaluation was made using Students t-test; significance was set at P ≤ .05. RESULTS The 3LP failed at a significantly (P = .0001) greater load (363.5 ± 83.7 N) than SA (132.4 ± 26.8 N), but the load to a 2 mm gap (3LP = 164.9 ± 67.7 N, SA = 114.5 ± 21.5 N) was not significantly different (P = .09). Failure mode was by suture pull out and anchor pull out respectively. The gap at failure was significantly larger in the 3LP than in SA repair (P = .000005). CONCLUSIONS Both the SA repair and the 3LP resisted similar tension to 2 mm gap. However, the ultimate load to failure of the SA repair was only 36% that of the 3LP repair.

Trauma and Wound Management: Gunshot Wounds in Horses

Bullet wounds in horses can cause a wide array of injuries, determined by the type of projectile, the energy of the bullet on entry, and the type of tissue the bullet encounters. Treatment includes identification of all structures involved, debridement of the permanent cavity, and establishing adequate drainage. Bullet wounds should be treated as contaminated, and broad-spectrum antibiotics, including those with an anaerobic spectrum, are indicated. Although musculoskeletal injuries resulting from gunshots are most common in horses, they carry a good prognosis for survival and return to function.

Evaluation of intra-abdominal pressure in horses that crib.

OBJECTIVE To measure intra-abdominal pressure (IAP) in horses that crib and compare it with IAP in horses that do not have this vice. STUDY DESIGN Cohort study. ANIMALS Healthy cribbing horses (cribbing cohort, n = 8) and 8 healthy noncribbing horses (noncribbing cohort). METHODS A microsensor catheter was introduced into the peritoneal cavity through the right paralumbar fossa, using local anesthesia, for measurement of IAP. These pressures were recorded in 1-minute intervals for 2 hours, while the horses were standing tied in a stall. IAPs of cribbing horses were compared to the noncribbing cohort. RESULTS Baseline IAPs were not significantly different between cribbing and noncribbing cohorts (P = .076); however, IAPs in the cribbing cohort were significantly increased when compared with the noncribbing cohort, during active cribbing behavior (P = .0016). Frequency of cribbing was not associated with increased IAP (P = .35). IAPs in the cribbing cohort remained significantly elevated compared with the noncribbing cohort, even after the behavior had ceased (P = .0002). CONCLUSION Cribbing is associated with increased IAP in the horse, both during and after the behavior.Objective To measure intra-abdominal pressure (IAP) in horses that crib and compare it with IAP in horses that do not have this vice. Study Design Cohort study. Animals Healthy cribbing horses (cribbing cohort, n = 8) and 8 healthy noncribbing horses (noncribbing cohort). Methods A microsensor catheter was introduced into the peritoneal cavity through the right paralumbar fossa, using local anesthesia, for measurement of IAP. These pressures were recorded in 1-minute intervals for 2 hours, while the horses were standing tied in a stall. IAPs of cribbing horses were compared to the noncribbing cohort. Results Baseline IAPs were not significantly different between cribbing and noncribbing cohorts (P = .076); however, IAPs in the cribbing cohort were significantly increased when compared with the noncribbing cohort, during active cribbing behavior (P = .0016). Frequency of cribbing was not associated with increased IAP (P = .35). IAPs in the cribbing cohort remained significantly elevated compared with the noncribbing cohort, even after the behavior had ceased (P = .0002). Conclusion Cribbing is associated with increased IAP in the horse, both during and after the behavior.

In Vitro Evaluation of the Size, Knot Holding Capacity, and Knot Security of the Forwarder Knot Compared to Square and Surgeon's Knots Using Large Gauge Suture

OBJECTIVE To investigate the strength, size, and holding capacity of the self-locking forwarder knot compared to surgeons and square knots using large gauge suture. STUDY DESIGN In vitro mechanical study. STUDY POPULATION Knotted suture. METHODS Forwarder, surgeons, and square knots were tested on a universal testing machine under linear tension using 2 and 3 USP polyglactin 910 and 2 USP polydioxanone. Knot holding capacity (KHC) and mode of failure were recorded and relative knot security (RKS) was calculated as a percentage of KHC. Knot volume and weight were assessed by digital micrometer and balance, respectively. ANOVA and post hoc testing were used tocompare strength between number of throws, suture, suture size, and knot type. P<.05 was considered significant. RESULTS Forwarder knots had a higher KHC and RKS than surgeons or square knots for all suture types and number of throws. No forwarder knots unraveled, but a proportion of square and surgeons knots with <6 throws did unravel. Forwarder knots had a smaller volume and weight than surgeons and square knots with equal number of throws. The forwarder knot of 4 throws using 3 USP polyglactin 910 had the highest KHC, RKS, and the smallest size and weight. CONCLUSION Forwarder knots may be an alternative for commencing continuous patterns in large gauge suture, without sacrificing knot integrity, but further in vivo and ex vivo testing is required to assess the effects of this sliding knot on tissue perfusion before clinical application.