Complications associated with the use of indwelling epidural catheters in dogs: 81 cases (1996-1999).

OBJECTIVE: To evaluate complications associated with use of indwelling epidural catheters in dogs in a clinical setting. DESIGN: Retrospective clinical study. ANIMALS: 81 client-owned dogs. PROCEDURE: Medical records were reviewed for dogs in which a 19-gauge epidural catheter was placed percutaneously at L7-S1 and advanced to the point of maximum efficacy for pain control (between L7 and T4, depending on the procedure). Catheters were used to provide perioperative epidural analgesia during surgeries that included perineal (n = 6), hind limb (33), abdominal (43), thoracic (5), forelimb (2), and cervical (1) procedures. RESULTS: Catheters were maintained in situ from 1 to 7 days (mean, 2.3 days; median, 2.0 days). Sixty-four dogs did not have complications; 17 dogs had minor complications. Catheter dislodgement was the most common complication (13/80 [16%] dogs). Catheter site contamination without inflammation developed in 2 (2.4%) dogs; inflammation at the catheter site developed in 2 (2.4%) dogs but was not related to duration of time the catheter was in place. Complications were not serious and did not require treatment other than catheter removal. Dogs that dislodged their catheters were significantly younger (mean, 2.9 years; median, 2.0 years) than other dogs (mean, 6.2 years; median, 6.0 years). Dogs that received femoral fracture repair dislodged their catheters more often (62.5%) than dogs undergoing other procedures (10.9%). CONCLUSIONS AND CLINICAL RELEVANCE: The complication rate associated with temporary epidural catheterization of dogs appears to be low, and complications generally are not serious.

Comparison of esophageal Doppler monitor generated minute distance and cardiac output in a porcine model of ventricular fibrillation.

The primary goal of cardiopulmonary resuscitation (CPR) is to increase cardiac output (CO), providing adequate tissue perfusion and oxygenation to maintain normal organ function. A non-invasive, easy to use, commercially available esophageal doppler monitor (EDM, Deltex) has been found to provide minute distance (MD), which is the distance moved by a column of blood through the aorta in 1 min. The goal of our study was to determine if CO measurements correlate with the EDM MD, before and during cardiac arrest, in a porcine model of ventricular fibrillation. Twenty pigs were anesthetized and an EDM was placed. MD measurement using EDM, and CO measurement using florescent microsphere injections were compared before and during CPR. MD correlated well with CO (r2 = 0.96) before and during CPR. Based on the excellent correlation between MD as determined by EDM and CO by florescent microsphere technique, it appears that the non-invasive use of the EDM may play a valuable role in determination of CO during CPR.

The leukocyte integrin alpha D beta 2 binds VCAM-1: evidence for a binding interface between I domain and VCAM-1.

The trafficking of leukocytes through tissues is supported by an interaction between the beta 2 (CD18) integrins CD11a/CD18 (LFA-1) and CD11b/CD18 (Mac-1) and their ligand ICAM-1. The most recently identified and fourth member of the beta 2 integrins, alpha D beta 2, selectively binds ICAM-3 and does not appear to bind ICAM-1. We have reported recently that alpha D beta 2 can support eosinophil adhesion to VCAM-1. Here we demonstrate that expression of alpha D beta 2 in a lymphoid cell that does not express alpha 4 integrins confers efficient binding to VCAM-1. In addition, a soluble form of alpha D beta 2 binds VCAM-1 with greater efficiency relative to ICAM-3. The I domain of alpha D contains a binding site for VCAM-1 since recombinant alpha D I domain binds specifically to VCAM-1. In addition, alpha D mAb that block cellular binding to VCAM-1 bind the alpha D I domain. Using VCAM-1 mutants we have determined that the binding site on VCAM-1 for alpha D beta 2 overlaps with that of alpha 4++ integrins. Substitution of VCAM-1 aspartate at position 40, D40, within the conserved integrin binding site, diminishes binding to alpha D beta 2 and abrogates binding to the alpha D I domain. The corresponding integrin binding site residue in ICAM-3 is also essential to alpha D beta 2 binding. Finally, we demonstrate that alpha D beta 2 can support lymphoid cell adhesion to VCAM-1 under flow conditions at levels equivalent to those mediated by alpha 4 beta 1. These results indicate that VCAM-1 can bind to an I domain and that the binding of alpha D beta 2 to VCAM-1 may contribute to the trafficking of a subpopulation of leukocytes that express alpha D beta 2.

The use of polymeric liquid enteral diets for nutritional support in seriously ill or injured small animals: clinical results in 200 patients.

This prospective, multicenter study evaluated the use of four polymeric liquid enteral (PLE) diets manufactured for dogs and cats in 200 ill or injured patients. Polymeric liquid enteral diets were administered by free-choice feeding, syringe, or feeding tube for up to 208 days. Overall results indicated a 4.9% incidence of vomiting in dogs and a 7.9% incidence in cats; an 8.9% incidence of diarrhea in dogs and an 18.4% incidence in cats. Patients fed the PLE diets seven days or longer had an average increase in body weight of 1.4% in dogs, an average decrease in body weight of 3.8% in cats, increases in lymphocyte counts, and mild decreases in serum albumin.

Esophagostomy tubes for feeding and decompression: clinical experience in 29 small animal patients.

Esophagostomy tubes were placed surgically in 13 dogs and 16 cats. The placement technique used was rapid and only required curved forceps, a scalpel blade, and suture material. Flexible tubes (5- to 30-French) were used for feeding liquids or blenderized diets for up to 557 days. Additionally, esophageal and gastric decompression were accomplished using these tubes. Following tube removal, all ostomy wounds healed by second intention without evidence of esophageal stricture or esophagocutaneous fistula. Complications included kinking, placement in an inappropriate location, obstruction, inflammation or infection of the ostomy site, and reflux of feedings.

The effects of endothelin-1 on coronary perfusion pressure during cardiopulmonary resuscitation in a canine model.

OBJECTIVE: To study the hemodynamic effects of exogenously administered endothelin-1 (ET-1), a peptide produced by endothelial cells with potent non-adrenergically mediated vasoconstrictor properties. METHODS: A prospective drug intervention study was carried out in a resuscitation research laboratory. Fifteen mixed-breed dogs were anesthetized and instrumented for hemodynamic monitoring. Asphyxia arrest was produced by clamping the endotracheal tube. Hemodynamic data were collected continuously. Following loss of aortic fluctuations monitored by thoracic aortic catheter, the animals remained in pulseless electrical activity (PEA) for 10 minutes. After 10 minutes of no-flow PEA, closed-chest CPR was begun and the animals were randomized to one of three treatment groups (EPI, 0.02 mg/kg epinephrine IV every 3 minutes; ENDO, 100 micrograms ET-1 IV at 0 minutes; and EPI/ENDO, a combination of the EPI and ENDO treatments). RESULTS: ENDO and EPI alone produced similar coronary perfusion pressures (CPPs). The EPI/ENDO combination produced significantly improved CPP compared with that of either EPI or ENDO alone. In the EPI group, the best mean CPP was 16 +/- 14 mm Hg and occurred 7 minutes after drug administration. In the ENDO group, the best mean CPP was 28 +/- 7 mm Hg and occurred 13 minutes after drug administration. In the EPI/ENDO combination group, the best mean CPP was 61 +/- 37 mm Hg and occurred 7 minutes after drug administration (p < 0.05 compared with the EPI and ENDO groups alone). CONCLUSION: ET-1 is a potent vasoconstrictor. The combination of EPI and ENDO significantly improved CPP compared with that for either agent alone. ET-1 should be investigated further as a vasoconstrictor in cardiac arrest.

Similar but nonidentical amino acid residues on vascular cell adhesion molecule-1 are involved in the interaction with alpha 4 beta 1 and alpha 4 beta 7 under different activity states.

The integrin receptors alpha 4 beta 1 and alpha 4 beta 7 both bind to vascular cell adhesion molecule-1 (VCAM-1). Here, we report that the amino acid residue requirements for murine VCAM-1 adhesion to murine alpha 4 beta 1 (WEHI 231) and alpha 4 beta 7 (38C13/beta 7-transfectant) positive cells are strikingly similar but nonidentical under multiple adhesion activity states. By site-directed mutagenesis of domain 1 of VCAM-1, the amino acid residues on the loop between beta strands C and D (R36, Q38, I39, D40, P42) and on the adjacent antiparallel beta strand F (L70 and T72) were required for basal level adhesion to both alpha 4 beta 1-positive and alpha 4 beta 7-positive cells. Mutation at two other sites, N44 (loop between beta strands C and D) and E66 (loop between beta strands E and F), specifically reduced alpha 4 beta 7-positive cell adhesion, but not alpha 4 beta 1-positive cell adhesion. Mutation H85A augmented alpha 4 beta 7 binding but not alpha 4 beta 1 binding. These apparent differences relate to the higher intrinsic activity state of alpha 4 beta 1 on WEHI 231 than on alpha 4 beta 7 (38C13/beta 7-transfectant). In contrast, under higher adhesion activity states induced by either MnCl2 or truncation of the beta 7 cytoplasmic tail, mutation of either amino acid residue D40 or L70 completely blocked cell adhesion without evidence of structural perturbation of VCAM-1. These results suggested that the two structurally discontinuous amino acid residues, the negatively charged D40 and the hydrophobic L70 adjacently located on domain 1 of VCAM-1, are essential for interaction under multiple activity states with both alpha 4 beta 1 and alpha 4 beta 7 integrin receptors.

Evaluation of an esophageal Doppler probe for the identification of experimental pseudo-electromechanical dissociation: a preliminary study.

STUDY OBJECTIVE: To determine the effectiveness of an esophageal doppler device to non-invasively detect experimental pseudo-electromechanical dissociation (pseudo-EMD). DESIGN: Prospective, controlled, laboratory investigation using an asphyxial canine cardiac arrest model and a newly-developed esophageal flat-flow probe doppler unit. INTERVENTIONS: Mongrel dogs (20) were instrumented for hemodynamic monitoring. The esophageal doppler probe was placed in the distal esophagus of each animal. Electromechanical dissociation (EMD) was induced by clamping the endotracheal tube. MEASUREMENTS AND MAIN RESULTS: A period of pseudo-EMD was defined as the time where cardiac contractility was present, measured by a micromanometer tipped thoracic aortic catheter, without concurrent femoral pulses by palpation. The pseudo-EMD period could be produced consistently in all 20 animals. The characteristic doppler flow sounds were easily heard using the esophageal device in all animals. The time from endotracheal tube clamping until loss of femoral pulses was 622 +/- 96 s; until loss of radial artery doppler signals was 616 +/- 92 s; until loss of esophageal doppler signals was 728 +/- 88 s; and until loss of aortic fluctuations by thoracic aortic catheter was 728 +/- 82 s. The times to loss of esophageal doppler sounds and loss of aortic fluctuations were not significantly different. However, they were significantly longer than the time to loss of femoral pulses (P < 0.02). CONCLUSIONS: The canine asphyxial EMD model can be used for short experimental studies of pseudo-EMD. Pseudo-EMD can be consistently and non-invasively detected with this esophageal doppler device. The device is as reliable as a micromanometer tipped aortic arch catheter in detecting pseudo-EMD. The doppler device could potentially be useful in improving recognition of near cardiac arrest in pre-hospital and emergency department settings. Further research on the utility of this device in other models of low-flow states should be performed.

Assessment and management of the hemorrhaging patient.

Trauma patients presenting to the veterinarian on an emergency basis commonly have bleeding injuries. Although mild hemorrhage is often self-limiting, severe hemorrhage may be lethal if not surgically controlled. Management of these patients requires rapid assessment and diagnostics so that appropriate treatment is provided in a timely manner. This article describes care of the hemorrhaging patient including assessment, immediate resuscitation, and principles of controlling the hemorrhage. External and surgical methods of treating hemorrhage are discussed, with a concentration on the surgical management of the hemorrhaging patient.

The emergency care of traumatic wounds: current recommendations.

Emergency management of wounds involves examination and protection of the wound with a wet dressing (when possible) to prevent further contamination and desiccation. Analgesia (or preferably anesthesia) is provided and the patient and the wound are prepared for surgery. Copious amounts of lavage solution are used under moderate pressure. Proper and thorough debridement under irrigation is tedious and time consuming, but is the most important factor that influences subsequent wound healing. Incomplete removal of devitalized or contaminated tissue and debris are a common cause of wound infection, breakdown, and delayed healing. Wound closure is only accomplished when the veterinarian is certain that all devitalized and contaminated tissue has been removed and there is adequate skin. Covering the wound to heal by second intention or delayed closure should be considered more often in veterinary medicine. All too often, the wound is closed prematurely, resulting in dehiscence and infection a few days later. This provides a source of complications to the pet, as well as a source of dissatisfaction for the client. If, after initial debridement and irrigation, there is any doubt about the advisability of surgical closure, the clinician should cover the wound with a proper dressing and continue daily (or more often) dressing changes with local irrigation and debridement as required. Drainage of wound fluid is critical to healing in contaminated wounds. Wound fluids interfere with healing and increase the likelihood of infection. Passive drains (Penrose) are frequently used, often incorrectly. The exposed end of passive drains should be covered with a sterile, absorbent dressing. Active drainage is more efficient than passive drainage and can be accomplished with minimal additional skill and material. Improper use of drains can cause more problems than no drainage at all. Patients suffering painful traumatic (or surgical) wounds should receive analgesic medications. The patient's response to pain may cause immunocompromise, resulting in increased infection rate. It may also induce a hypermetabolic state that may result in impaired wound healing, multiple organ dysfunction, and, possibly, death. Swelling in the area of wounds can create tension on the wound, which compromises the blood supply. Light pressure bandages are recommended to minimize swelling. Nutritional considerations should be given to the wounded patient. Additional protein, vitamins, and minerals may be required for immune function and wound repair.(ABSTRACT TRUNCATED AT 400 WORDS)

Regulation of the avidity of integrin alpha 4 beta 7 by the beta 7 cytoplasmic domain.

Integrins are cell-surface heterodimeric receptors with adhesive and transmembrane signaling properties. Their cytoplasmic domains can affect receptor avidity, cytoskeletal association, and post-receptor occupancy events. The alpha 4 beta 7 integrin mediates cell adhesion to Peyer's patch high walled endothelial venules (HEV), VCAM, and CS-1/fibronectin. To determine the role of the beta 7 cytoplasmic domain in these interactions, wild-type and truncated beta 7 subunits were stably expressed in the alpha 4+/beta 1-/beta 7- B cell lymphoma 38C13. The cell line delta 727 lacks the entire beta 7 cytoplasmic domain, delta 753 lacks the 34 C-terminal residues, and LXSN is vector-transfected 38C13. Cells expressing wild-type beta 7 bound Peyer's patch HEV, fibronectin, and immobilized VCAM constitutively and did not require prior activation with phorbol esters. Interestingly, delta 753 displayed no ligand binding activity, while delta 727 was constitutively active for all ligands and displayed greater avidity for fibronectin and Peyer's patch HEV than the wild-type beta 7. beta 7, delta 753, delta 727, and LXSN were also tested for the ability to bind soluble VCAM in the presence of various divalent cations. In the presence of Ca2+, but not Mg2+, delta 727 constitutively bound soluble VCAM, whereas beta 7, delta 753, and LXSN did not. beta 7 and delta 753 could bind soluble VCAM if first activated with Mn2+. The results suggest that: (i) alpha 4 beta 7 can be expressed in a constitutively active state, (ii) the beta 7 cytoplasmic domain regulates the avidity of alpha 4 beta 7, and (iii) 38C13 cell lines expressing wild-type and truncated beta 7 subunits define three stable activation states of alpha 4 beta 7: inactive (delta 753), partially active (beta 7), and fully active (delta 727) receptors.

Rapid tissue expansion for the development of rotational skin flaps in the distal portion of the hindlimb of dogs: an experimental study.

In phase I, tissue expanders were implanted subcutaneously over the lateral crural region of four dogs. The expanders were inflated daily to maintain a constant intraluminal pressure for 7 days. All animals tolerated the pressurized expanders well. Some animal patient discomfort was associated with repeated injections into the subcutaneous filling port. One dog developed a limited area of tissue loss and exposure of the expander. Tissue response to the expanders included epidermal hyperplasia, dermal collagen compression with early fibroplasia, and subcutaneous granulation tissue formation adjacent to the expander pocket. In phase II, a second group of four dogs underwent rapid skin expansion over 7 days. The pressure applied to the expanding skin was determined daily and adjusted to approximate the value reported for capillary pressure in the dog. Tissue discoloration occurred in two dogs, suggestive of impaired circulation. Skin flaps were developed from expanded skin and rotated over the talocrural region. Wound dehiscence occurred along the distal flap margin in three phase II dogs. These wounds healed by second intention. Branches of the caudal saphenous artery were identified, using angiography, as the primary blood supply to the skin flaps.

Cloning and expression of mouse integrin beta p(beta 7): a functional role in Peyer's patch-specific lymphocyte homing.

Lymphocytes express integrin receptors, termed lymphocyte Peyer's patch high endothelial venule (HEV) adhesion molecules (LPAMs), that mediate their organ-specific adhesion to specialized HEVs found in mucosal lymphoid organs (Peyer's patches). LPAM-1 consists of a murine integrin alpha 4 noncovalently associated with integrin beta p. Here, we describe the cloning and expression of a mouse cDNA encoding beta p, which is an 806-amino acid transmembrane glycoprotein. The genomic Southern blot analysis indicates that beta p is the murine homologue of human beta 7. The function of alpha 4 beta 7 as a Peyer's patch-specific adhesion molecule was tested directly by expression of the murine beta 7 cDNA in an alpha 4+ beta 7-B-cell line or coexpression of the alpha 4 and beta 7 cDNAs in an alpha 4-beta 7-T-cell line. The transfected cells exhibited a new Peyer's patch-specific adhesive phenotype that could be specifically blocked by monoclonal antibodies against alpha 4 and beta 7. Moreover, an anti-beta 7 monoclonal antibody specifically blocked binding of normal lymphocytes to Peyer's patch HEV but did not inhibit their binding to peripheral lymph node HEVs, indicating that beta 7 is a unique component of the Peyer's patch-specific homing receptor.

Cardiopulmonary resuscitation: current recommendations.

Early recognition of CPA is the key to its successful management. For resuscitation to be managed successfully, effective forward blood flow must be established at the onset of the arrest. In our clinical experience, we have found that the Doppler unit allows us to assess the effectiveness of cerebral perfusion better than any other method of blood pressure evaluation. If, by Doppler monitoring results, cerebral perfusion is found to be poor, blood flow may be mechanically improved by instituting high dose epinephrine therapy and interposed abdominal counter-pressure techniques. There is an understandable reluctance on the part of many veterinarians to enter the chest in the course of CPR. Unfortunately, this delay in performing internal compressions is often the reason that open-chest CPR is deemed ineffective by so many practitioners. If external chest CPR is not effective within 1 to 2 min (maximum) of its initiation, an emergency thoracotomy and direct cardiac massage should be performed. We know that perfusion pressure increases three to five times with open versus closed-chest CPR. This improvement in perfusion with direct cardiac massage is due, in part, to the absence of venous pressure elevations created during external chest compression. It follows that better coronary and cerebral blood flow will result in better resuscitation when direct cardiac massage is performed early. The "bottom line" in CPR is successful resuscitation of the patient with resultant good neurologic function. It is hoped that through the use of these techniques and new cytoprotective drugs, the survival rate will rise.

Mutagenesis of the rat insulin II 5'-flanking region defines sequences important for expression in HIT cells.

To define the cis-acting elements important for rat insulin II gene expression, we analyzed the effects of 5' deletions and linker-scanning mutations on the expression of a rat insulin II reporter gene in an insulinoma cell line (HIT). The reporter gene contained 448 base pairs of 5'-flanking sequence joined to the bacterial chloramphenicol acetyltransferase gene. Expression of the 5' deletion mutations indicated that the minimal sequence requirement for efficient expression was 218 base pairs of 5'-flanking sequence, and at least three regions downstream from - 218 were important for transcription. A more precise localization of these elements and the cis-acting sequences in the promoter was achieved by analysis of the expression of 18 linker-scanning mutations. In these studies at least four other regions important for expression of the rat insulin II gene were identified. These findings suggest that the sequences important for rat insulin II and rat insulin I expression may differ significantly despite the high degree of sequence similarity in their 5'-flanking regions.