A Study of the Biomechanical Properties of the Adult Equine Linea Alba: Relationship of Tissue Bite Size and Suture Material to Breaking Strength

The purposes of this study were to mechanically determine the optimal tissue bite size and to evaluate seven suture materials at their largest commercially available size for breaking strength and stiffness using cadaveric adult equine linea alba. Soft tissues were removed from the abdominal fascia of 16 adult horses. Individual test sections were created from the entire linea alba and labeled (1 through 6) starting at the umbilicus and extending craniad. A single biomechanical test was performed on each test section. Tissue bite size (3, 6, 9, 12, 15, 18, and 21 mm) significantly altered breaking strength directly in a logarithmic fashion (P < .0001; R²= 0.94). Tissue bite size accounted for 44% and linea alba thickness for 24% of the variability in breaking strength of the equine linea alba. The optimal tissue bite size for adult horses was 15 mm from the edge of the linea alba based on lack of significant gain in breaking strength. There were no differences in breaking strength among horses, horses weight, or left and right test sections. Test sections taken from near or at the umbilicus had greater breaking strength (P < .005) and thicker linea alba (P < .001) when compared with more cranial test sections. Linea alba thickness alone accounted for 34% of the variability in breaking strength associated with test section position. There were no differences in linea alba stiffness among tissue bite sizes. All suture loops failed before complete fascial disruption, and 52 of 56 (93%) suture loops failed at the knot. Suture breaking strength and stiffness were significantly affected by the type of suture material examined (P < .0001). Size 5 polyester had a greater breaking strength and stiffness compared with the other suture materials tested. The next strongest suture materials were size 3 polyglactin 910 and size 2 polyglycolic acid, which were similar in breaking strengths and stiffness. Size 2 nylon was significantly weaker in breaking strength when compared with the other suture materials.     

Tissue strength and wound morphology of the equine linea alba after ventral median celiotomy

OBJECTIVE: To evaluate the tensile strength and wound morphology of the equine linea alba at intervals over 6 months after ventral median celiotomy. STUDY DESIGN: Linea alba tensile strength and wound morphology were determined at 2, 4, 8, 16, and 24 weeks postoperatively. Linea alba samples from 3 unoperated horses were used as controls. ANIMALS: Eighteen adult horses, weighing 400 to 500 kg, 4 to 15 years old. METHODS: Tensile strength and thickness of incised linea alba samples collected at 2, 4, 8, 16, and 24 weeks after ventral median celiotomy were compared with control linea alba samples. Additional samples were subjectively evaluated for wound morphology, notably collagen morphology. RESULTS: Control linea alba had a mean (+/-SEM) tensile strength of 484.9 +/- 58.3 N and was significantly (P < or = .05) stronger than at 2 weeks (87.7 +/- 61.4 N) after surgery. The tensile strength of 4-week (305.8 +/- 61.7 N), 8-week (465.4 +/- 56.5 N), and 16-week (477.8 +/- 57.2 N) samples were not significantly different from control linea alba. At 24 weeks, the tensile strength (721.0 +/- 57.9 N) was significantly stronger than control. The 2-, 4-, and 8-week samples were significantly thicker than controls, whereas the 16- and 24-week samples were not different from controls. On microscopy, control samples were characterized by dense mature collagen bundles. At 2 weeks, samples consisted primarily of granulation tissue, whereas at 4 weeks, samples had immature collagen fibers that were not formed into bundles, and at 8, 16, and 24 weeks, all samples had abundant mature collagen fibers formed into bundles. CONCLUSIONS: At 8 weeks, incised and sutured equine linea alba had a tensile strength comparable with non-incised linea alba and was characterized by mature collagen. CLINICAL RELEVANCE: Based on tensile strength and wound morphology, horses that have had an uncomplicated recovery after ventral median celiotomy should be able to return to controlled exercise as early as 60 days after surgery.     

Comparison of Stainless Steel Fascial Staples and Polypropylene Suture Material for Closure of the Linea Alba in Dogs

Five centimeter segments of the linea alba in mature, female, mixed breed dogs were incised and then approximated with either stainless steel fascial staples or size 0 polypropylene suture material. Breaking strength of the linea alba closures was determined at 0 (Phase I, 18 dogs) and at 7,14, and 31 days (Phase II, 18 dogs). Histology and videointeractive planar morphometry were used to evaluate healing of the linea alba. Breaking strength and histologic and morphometric variables were analyzed statistically using analysis of variance in a split plot design. In a clinical trial, 20 cm linea alba incisions were approximated with stainless steel fascial staples after elective ovariohysterectomy in mature, female, mixed breed dogs (Phase III, eight dogs). The dogs were evaluated at 1, 2, 7,14, 31, 90, and 180 days. Linea alba incisions approximated with polypropylene suture material were significantly stronger than linea alba incisions approximated with stainless steel fascial staples on day 0. There was no significant difference between breaking strength values, histologic, and morphometric appearance of linea alba incisions closed with stainless steel fascial staples or polypropylene suture material when compared 7,14, and 31 days after surgery. All of the dogs in the clinical trial appeared to be normal at all evaluation times. Approximation of linea alba incisions with stainless steel fascial staples compares favorably to closure with a simple continuous pattern of polypropylene suture material with regard to breaking strength, clinical, histologic, and morphometric appearance.     

利多卡因、布吡卡因行硬膜外阻滞对羊肝、肾功能的影响

为研究利多卡因、布吡卡因硬膜外阻滞对山羊肝、肾功能的影响,将16只成年山羊被随机分成2组(n=8),L3-4之间行硬膜外穿刺、置管后,分别注入2%多利卡因6mg/kg和0.75%布吡卡因2mg/kg。在注药前及注药后的30min、24h、72h和120h采集血样,测定ALT、AST、ALP、γ-GT及LDH的活性和Bilirubin、Grea、UA和Gluc等生化指标。结果表明,利多卡因、布吡卡因行硬膜外阻滞对血清ALT、AST、ALP、γ-GT及LDH活性和Grea、Urea、Gluc和Bilirubin均没有明显影响。     

Long-term degeneration and regeneration of the rabbit facial nerve blocked with conventional lidocaine and bupivacaine solutions

The alterations due to the long-term degeneration and regeneration of the rabbit facial nerve were investigated. The facial nerve was blocked with conventional lidocaine and bupivacaine solutions. The rabbits were sacrificed and facial nerves were removed 2, 4, 6 and 8 weeks after the administration of normal saline, lidocaine and bupivacaine. The samples were then processed for electron microscopic observation. Degenerations were seen 2-4 weeks after the injection of normal saline, lidocaine and bupivacaine. In the normal saline group the regeneration process was observed after 6 weeks, whereas in the lidocaine and bupivacaine groups this process was first noticed after 8 weeks. In the lidocaine and bupivacaine groups, regeneration was not completed at the end of 8 weeks; however, it was faster in the bupivacaine group. Bupivacaine is therefore suggested as the drug of choice for neural blockade as it caused less damage and a faster regeneration.     

Postoperative Analgesia for Stifle Surgery: A Comparison of Intra-articular Bupivacaine, Morphine, or Saline

A prospective study was undertaken to compare the analgesic effect of intra-articular bupivacaine, morphine, or saline in the 24-hour period following cranial cruciate ligament repair in dogs. Thirty-six clinical patients with ruptured cranial cruciate ligaments were randomly assigned to one of three groups. After surgical stabilization, and before skin closure, an intra-articular injection was given; group one (n = 12) received 0.5% bupivacaine HCl at 0.5 mL/kg, group two (n = 12) received morphine at 0.1 mg/kg diluted with saline to a volume of 0.5 mL/kg, and group three (n = 12) received saline at 0.5 mL/kg. Heart rate, respiratory rate, mean arterial blood pressure, cumulative pain score, visual analog pain score, and pain threshold test on both stifles were recorded preoperatively and at 0 to 6 and 24 hours postoperatively. Surgeons and pain scoring investigators were unaware of the intra-articular medication given. Supplemental analgesia, if needed, was provided in the postoperative period according to subjective assessment of patient discomfort. Postoperative pain scores were lowest in the bupivacaine group and highest in the saline group. Pain threshold, measured by applying calibrated loads to the knee, was higher postoperatively in the bupivacaine group than in the saline group. Dogs in the morphine and bupivacaine groups required less supplemental analgesia than dogs in the saline group. The local provision of analgesia reduces the need for systemic drugs with potential side effects. Both intra-articular morphine and intra-articular bupivacaine provided better postoperative analgesia than intra-articular saline, with intra-articular bupivacaine showing the greatest effect.     

An in vitro biomechanical comparison of the breaking strength and stiffness of polydioxanone (sizes 2, 7) and polyglactin 910 (sizes 3, 6) in the equine linea alba

OBJECTIVE: To determine failure strength, stiffness, and failure mode of 4 suture materials in equine linea alba. STUDY DESIGN: Randomized complete block design. SAMPLE POPULATION: Linea albas collected from 12 adult horses (mean weight, 475 kg; mean age, 10 years). METHODS: The ventral abdominal fascia, including the linea alba, was collected and bisected along the linea alba into right and left halves. Each half was divided into four, 5-cm sections extending from the umbilicus cranially, and randomly assigned to 1 of 4 suture materials: 2 polydioxanone (2 PD), 3 polyglactin 910 (3 PG), 6 polyglactin 910 (6 PG), and 7 polydioxanone (7 PD). A single cycle to failure test was performed on each specimen at a distraction rate of 100 mm/min. Differences in failure strength and stiffness for the materials were evaluated using a mixed linear model with significance set at P<.05. RESULTS: In 94 of 96 test sections, constructs failed by suture failure. There were significant differences in failure strength (P<.0001) and stiffness (P<.001) among the suture/tissue constructs. 7 PD had the highest breaking strength (316.8 N) followed by 6 PG (281.3 N), 3 PG (229.9 N), and 2 PD (193.0 N). Six PG had the largest stiffness (14 N/mm) followed by 3 PG (12.7 N/mm), 7 PD (10.1 N/mm), and 2 PD (7.2 N/mm). Suture breaking strength and stiffness were not affected by linea or fascia thickness, individual horse, half of the linea alba, or abdominal wall position. Eighty-five (90.4%) suture loops failed adjacent the knot. CONCLUSIONS: When tested in single cycle to failure, suture material was more likely to fail than the linea alba. Larger suture materials had higher breaking strengths than smaller suture materials and stiffness was also affected by suture material and size. CLINICAL RELEVANCE: Given its high initial breaking strength and its relatively longer in vivo strength retention, 7 PD seems an appropriate choice of suture material for closure of the equine linea alba when maximal short-term failure strength is desired.     

Clinical and ultrasonographic evaluation of three suture techniques for closure of the equine linea alba

Surgical technique plays an important role in preventing ventral midline incisional complications. The aim of this study was to compare the clinical and ultrasonographic outcome of three suture techniques for closure of the linea alba. In this prospective case series (n = 43), horses operated for acute abdominal intestinal disease through a midline incision were randomised in three groups: closure with a conventional continuous technique (Group 1), a small stitches continuous technique (Group 2) and the UX-technique (shoe-lace configuration, Group 3). Age, sex, body weight, type and duration of surgery were recorded and the suture to wound length ratio was calculated. Clinical evaluation of the wound (wound discharge) was performed daily during hospitalisation. At 7 weeks post-operatively the linea alba was evaluated clinically and ultrasonographically. The linea alba width was measured halfway along the length of the incision. One horse in Group 1 had acute incisional dehiscence, but there were no further significant differences between the groups in the short term. Seven weeks post-operatively two horses had complete herniation in Group 1 and one horse had partial herniation in Group 2. In the UX group no herniation occurred. The incidence of herniation was not significantly different between the groups. On ultrasound at 7 weeks the linea alba width was significantly smaller in Group 2 (P = 0.00029) and Group 3 (P = 0.0018) compared with Group 1, even with exclusion of the acute incisional dehiscence and two herniated horses. Limitations were the small group size and relatively low incidence of incisional complications for statistical analysis. It was concluded that the use of small stitches and the UX-technique resulted in a smaller linea alba width compared with the conventional continuous suture technique and might therefore be preferred for closure of the linea alba in equine colic surgery.     

A Comparison of Epidural Saline, Morphine, and Bupivacaine for Pain Relief After Abdominal Surgery in Goats

The purpose of this study was to determine the analgesic efficacy of bupivacaine, morphine, or saline (control) when injected epidurally into the lumbosacral epidural space in goats after abdominal surgery. Goats received either bupivacaine (0.5%; 1.5 mg/kg in 0.9% sodium chloride solution), 0.9% sodium chloride solution (0.2 mL/kg), or preservative-free morphine (0.1 mg/kg). Total volume injected into the epidural space was 0.2 mL/kg for all groups. The variables evaluated were times to extubation, sternal recumbency, standing, and eating; heart and respiratory rates; and pain score. Only two of the goats in the bupivacaine group were able to stand on their hindlimbs before 6 hours. Time to eating was shorter for the saline group when compared with the bupivacaine group. Heart rate over all time in the saline group (137 ± 4 beats/min, mean ± SEM) was higher than the morphine (125 ± 3 beats/min) and bupivacaine groups (121 ± 3 beats/min). Respiratory rate over all time was increased in the saline group (26 ± 1 breaths/min) compared with the bupivacaine (24 ± 1 breaths/min) or morphine (24 ± 1 breaths/min) groups. At 50 minutes, the pain score for the saline group was higher than the morphine group. Pain score over all time in the saline group (1.5 ± 0.10) was higher than the morphine (1.2 ± 0.07) and bupivacaine (1.2 ± 0.04) groups. One goat in the saline group required two intravenous injections of flunixin meglumine for pain.     

Effect of flunixin meglumine on surgical wound strength and healing in the rat

Forty male adolescent Sprague-Dawley rats were anesthetized and standardized ventral midline laparotomies and uniform-length gastrotomies and typhlotomies were performed. The visceral and abdominal surgically inflicted wounds were closed with 5-0 polypropylene and 4-0 nylon suture, respectively. The rats were allotted into 4 groups (10 rats/group); 2 groups were not given flunixin meglumine (controls) and 2 groups were given flunixin meglumine (1.1 mg/kg of body weight, IM, every 12 hours). On day 5 and again on day 14 after surgery, 1 control and 1 flunixin meglumine-treated group were euthanatized. Tensile strength of the skin and linea alba incisions was determined, using a computerized tensiometer. Gastric and cecal incision bursting strengths were determined, using a pressure manometer. Flunixin meglumine significantly (P less than 0.05) decreased the tensile strength of wounds in the skin and linea alba, but did not affect visceral bursting strength at day 5 after surgery. At day 14 after surgery, a significant difference in wound strength was not found between the flunixin meglumine and control groups in any of the tissues evaluated. Flunixin meglumine had an adverse influence on the inflammatory stage of wound repair, but not on the proliferative stage, when fibroplasia is a major factor in wound strength. Major histologic differences were not found in the incision wounds of flunixin meglumine-treated and nontreated control rats.     

Comparison of polyglactin-910 and polydioxanone for closure of the linea alba following caudal ventral midline laparotomy in sheep

This study compared incisional complications after ventral midline laparotomy using 2 absorbable suture materials for apposition of the linea alba in sheep. The linea alba of 93 yearling sheep was sutured by 3 veterinarians in a simple continuous pattern using either polyglactin 910 (PG910; group PG) or polydioxanone (PDS; group PD). A blinded observer assessed surgical sites at the time of suture removal. Multivariate logistic regression was used to assess the association between incisional complications and variables (suture material used, veterinarian, skin suture removal time). The odds of incisional complications did not vary significantly with the type of suture material used (P = 0.11), veterinarian (P = 0.61) or skin suture removal time (P = 0.36). Most incisional complications were cutaneous suture sinus formation. Either PG910 or PDS may be used for linea alba closure in sheep.     

Effects of Surgical Wound Infiltration with Bupivacaine on Postoperative Analgesia in Cats Undergoing Bilateral Mastectomy

The analgesic effect of wound infiltration with bupivacaine was evaluated in cats undergoing bilateral mastectomy. Twenty-one female cats with mammary gland tumors were anesthetized with propofol and oxygen-isoflurane anesthesia following premedication with atropine. In the trial group (Group I; n=11), 30 ml of saline containing 2 mg/kg of bupivacaine was infiltrated topically into the surgical wound right after removal of the mammary glands, whereas only saline solution was infiltrated in the control group (Group II; n=10). At the same time, carprofen (4 mg/kg) was also administered subcutaneously in both groups. Behavioral signs of pain were monitored during the recovery period after general anesthesia. In order to examine the behavioral changes associated with acute pain, a questionnaire was prepared and given to the owners to be completed 4 hr and then 10 hr after the operation. According to the owners’ anwers to the questionnaire, a pain score was specified using a “numerical rating scale” for each cat. Although some cats showed mild to moderate pain, the pain score recorded at 4 hr after the operation was significantly lower in Group I (P<0.001). No significant difference was found at 10 hr after the operation between the groups. The incidence of vocalization, aggression and convulsion within 2 hr after the operation was also lower in Group I. In conclusion, wound infiltration with bupivacaine before incisional closure provided reliable analgesia at least 4 hr after bilateral radical mastectomy in cats.     

Occurrence of Incisional Complications After Closure of Equine Ventral Midline Celiotomies With 2 Polyglycolic Acid in Simple Interrupted Suture Pattern

The aim of this retrospective study was to describe the use of simple interrupted suture pattern for the closure of the abdomen after ventral midline celiotomy in horses and to evaluate the prevalence of resulting incisional complications. Seventy horses undergoing abdominal surgery (2006–2015) and surviving at least 30 days were included in the study. Closure technique of the abdominal wall was performed on three layers. Linea alba was closed with a simple interrupted pattern using number two coated braided absorbable polyglycolic acid suture. Follow-up information was recovered at the 90th day postoperatively. Incisional complications considered included drainage, infection, dehiscence, and herniation. The complications observed in the present study using simple interrupted suture pattern were 4.29% (3 of 70), lower than reported in literature with different suture pattern. Simple interrupted suture pattern could be a valid option for the closure of linea alba after ventral midline celiotomy in horses.     

Incisional Hernias in the Horse Incidence and Predisposing Factors

Medical records of 210 horses that survived ventral midline celiotomy for at least 4 months were examined and owners were queried to determine factors contributing to incisional hernia formation. The incidence rate of incisional hernias within 4 months was 16%. Factors significantly associated with occurrence of incisional hernias were incisional drainage, closure of the linea alba with chromic gut suture material, previous midline celiotomy, excessive incisional edema, castrated male sex, postoperative leukopenia, and postoperative pain (colic). Factors not significantly associated with occurrence of incisional hernias were suture pattern used for linea alba closure, concurrent enterotomy or intestinal resection, postoperative bandage or stent, postoperative fever, hypoproteinemia, diarrhea, respiratory disease (coughing), and peritonitis. Hernias developed in horses within 12 weeks of surgery, with the earliest hernia recognized at week 2. Of 30 horses for which information was available, only one hernia developed in 24 (80%) and two or more hernias developed in 6 (20%) along the incision. Multiple hernias tended to be smaller than single hernias.     

Factors affecting incisional complication rates associated with colic surgery in horses: 78 cases (1983-1985)

From May 1, 1983 to April 1, 1985, 142 operations were performed on horses with signs of acute abdominal pain (colic), using a ventral midline incision. Seventy-eight horses lived for at least 15 days after surgery or had acute dehiscence and were included in the study. Seventy horses had surgery once, and 8 horses had surgery 2 or more times. Six-month follow-up evaluation was obtained for 66 horses that had 1 surgery and for 6 horses that had multiple surgeries. Incisional complications included drainage (including infection), acute dehiscence, hernia, and suture sinus formation. The effects of preoperative peritoneal fluid presence, enterotomy or resection, suture material and pattern used in the linea alba, type of skin closure and use of a sutured-on stent bandage on the incidence of incisional complications were investigated. The complication of incisional infection rate associated with a near-far-far-near suture pattern vs simple interrupted pattern in the linea alba was the only statistically significant (P less than 0.05) difference observed.     

Intravenous lidocaine and small-intestinal size,abdominal fluid,and outcome after colic surgery in horses

Twenty-eight horses with the diagnosis of an intestinal disorder requiring surgical intervention were randomly assigned to lidocaine (n = 13) or saline (control, n = 15) treatment groups. After induction of anesthesia, treated horses received a loading dose of 2% lidocaine (0.65 mg/kg) intravenously, followed by a continuous rate of infusion of 1% lidocaine (0.025 mg/kg/min) until the discontinuation of anesthesia. Upon recovery from anesthesia, a 2nd loading dose of 2% lidocaine (1.3 mg/kg) was administered, followed by an infusion of 1% lidocaine (0.05 mg/kg/min) for 24 hours postoperatively. The control group received equivalent volumes of saline. Lidocaine-treated horses had significantly better minimum jejunal cross-sectional area scores (P = .011), minimum jejunal diameter scores (P = .002), and intestinal ultrasound index (IUI) (P = .007). Peritoneal fluid was detected by percutaneous ultrasound examination in 8 of the 15 control animals but in none of the treated animals (P = .003). Failure to obtain fluid via abdominocentesis was significantly more frequent for lidocaine-treated horses (P = .025). No significant differences between the groups were found in the presence of gastrointestinal sounds, time to passage of 1st feces, number of defecations in the 1st 24 hours, presence of gastric reflux, duodenal or jejunal wall thickness, maximum duodenal or jejunal diameter or cross-sectional area, minimum duodenal diameter or cross-sectional area, duodenal and jejunal intraluminal echogenicity, small-intestinal contractions per minute, rate of complications, or outcome. On the basis of this study, lidocaine infusion may have some desirable effects on jejunal distension and peritoneal fluid accumulation and was well tolerated perioperatively in horses with colic. The low incidence of small-intestinal lesions and gastric reflux in the study makes it difficult to assess the use of lidocaine in the prevention of postoperative ileus (POI).     

Epidural analgesia with 0.75% bupivacaine for laparotomy in goats

Epidural nerve block with 0.75% bupivacaine (1 ml/4 kg of body weight) was performed in 17 goats tranquilized by IM administration of acetylpromazine (0.07 mg/kg). For comparison, epidural nerve block with 2% lidocaine containing 1:100,000 epinephrine (1 ml/5 kg) was performed in 7 goats. Transient signs of CNS stimulation were observed during injection of bupivacaine in 5 goats and of lidocaine in 2 goats. Analgesia of the flank was inadequate for laparotomy in 4 goats given bupivacaine (including 1 goat given a two-thirds dose) and in 2 goats given lidocaine. Analgesia for these goats was provided by local infiltration of the operative site with lidocaine. With bupivacaine, the onset of analgesia was up to 40 minutes, and the duration of analgesia was several hours; most goats were unable to stand for at least 11 hours. In comparison, epidural nerve block with lidocaine had a more rapid onset and much shorter duration. For both anesthetic drugs, despite adequate analgesia for laparotomy, response to manipulation of abdominal viscera was observed in 12 goats. Arterial blood pressure and blood gas tensions were measured in 8 goats given bupivacaine; 3 goats had mean arterial blood pressure less than 70 mm of Hg. Seven goats had normal PaCO2 but 2 goats had low PaO2; 1 goat sedated with xylazine had increased PaCO2 and hypoxemia.     

Tissue Reaction to Suture Material in the Feline Linea Alba A Retrospective, Prospective, and Histologic Study

Swelling and inflammation along the incision line were observed after elective ovariohysterectomy in 22 of 66 cats in a retrospective study. In a prospective study of 99 feline abdominal incisions closed with surgical gut, polyglactin 910, or polydioxanone, with and without subcutaneous closure, the least inflammation occurred when the linea alba was sutured with polyglactin 910 and the subcutaneous tissues were not sutured. Histologically, reactions in the linea alba of 12 other cats progressed from purulent to fibromononuclear to fibrous within 14 days after closure with gut, polyglactin 910, and polydioxanone. Microscopic evidence of seroma formation in 9 of 12 animals in which the subcutaneous tissue was not sutured suggested that surgical closure of subcutaneous dead space was indicated. The inflammatory reaction did not appear to be related to any one suture material as reactions were seen with all of them.     

Perineal analgesia and hemodynamic effects of the epidural administration of meperidine or hyperbaric bupivacaine in conscious horses

Epidural administration of bupivacaine and meperidine produces analgesia in several animal species and in humans. A prospective randomized study was conducted in 18 healthy horses to compare the effect of these 2 drugs administered by the epidural route. Animals were divided into 3 treatment groups of 6 animals each. All drugs were injected by the epidural route in all animals between the 1st and 2nd coccygeal vertebrae. Treatment 1 (BUP)--0.06 mg/kg of body weight of 0.5% hyperbaric bupivacaine; treatment 2 (MEP)--0.6 mg/kg of body weight of 5% meperidine; treatment 3 (SS)--0.9% saline solution (control group). Heart rate, arterial pressure, respiratory rate, rectal temperature, analgesia, sedation, and motor-blocking were determined before drug administration (baseline values); at 5, 10, 15, and 30 minutes after drug administration, and then at 30-minute intervals thereafter. Both hyperbaric bupivacaine and meperidine administered epidurally produced complete bilateral perineal analgesia in all horses. The onset of analgesia was 6, s = 2.6 minutes after injection of bupivacaine, as opposed to 9, s = 2 minutes after meperidine. The duration of analgesia was 240, s = 57 minutes for meperidine and 320, s = 30 minutes for bupivacaine. Heart and respiratory rates, arterial pressure, and rectal temperature did not change (P < 0.05) significantly from basal values after the epidural administration of bupivacaine, meperidine, or saline solution. To conclude, both bupivacaine and meperidine induced long-lasting perineal analgesia, with minimal cardiovascular effects. Analgesia was induced faster and lasted longer with bupivacaine.     

Hemodynamic effects of interpleural lidocaine and bupivacaine combination in anesthetized dogs with and without an open pericardium

OBJECTIVE: To identify dysrhythmias and hemodynamic changes after lidocaine and bupivacaine infusion into the interpleural space with an open pericardium. STUDY DESIGN: Experimental study. ANIMALS: Six adult dogs. METHODS: Systemic arterial pressure and electrocardiogram were recorded. A 7.5 Fr Swan-Ganz catheter was advanced to the level of the main pulmonary artery to record pulmonary arterial pressure. Cardiac output was measured by a thermodilution technique. A pericardial window (PW) was performed in 3 dogs using thoracoscopy. Hemodynamic variables were recorded before and 15 minutes after injection of lidocaine (1.5 mg/kg) and bupivacaine (1.5 mg/kg) into the pleural space in the control group and in the pericardial space for the PW group. A randomized-block ANOVA for repeated measures was used to evaluate the effect of local anesthetic administration on hemodynamic and electrophysiologic variables in dogs with a pericardectomy. RESULTS: Each dog maintained sinus rhythm. Infusion of local anesthetic induced a significant increase in right ventricular diastolic pressure (P = .002) and a significant decrease in stroke volume (P = .047) in both groups; however, the effects were not significantly different between groups. CONCLUSIONS: Infusion of lidocaine and bupivacaine, either intrapleural or in the pericardial space, had a mild detrimental effect on cardiac output. CLINICAL RELEVANCE: Intrapleural administration of lidocaine and bupivacaine at a therapeutic dose can be used safely in healthy dogs with a pericardectomy.