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Future directions in veterinary critical care
VOLUME 18 ISSUE 6 JUNE 2005
Advances in Small Animal Medicine and Surgery Future Directions in Veterinary Critical Care Alisa Reniker, DVM Diplomate, American College of Veterinary Emergency and Critical Care Clinical Assistant Professor College of Veterinary Medicine University of Missouri Columbia, MO 65211 INTRAVENOUS SURFACTANTS IN PARAPLEGIC DOGS Researchers are currently investigating the use of polyethylene glycol (PEG) and PEG-like polymers as adjunctive therapies for acute spinal cord injury (SCI) in dogs.1 These compounds have surfactant effects and act as membrane sealants. This effect has been previously studied after crushed nerve or spinal cord injury in laboratory animals. Dogs with severe SCI and no deep nociception after Hansen type I intervertebral disk extrusion served as a naturally occurring animal model to evaluate efficacy and safety of PEG. Each dog received complete physical and neurological examinations, myelography, and surgical decompression with removal of extruded disc material. Additionally, dogs received intravenous injections of methylprednisolone and PEG. Neurologic examinations were repeated using a scoring system to evaluate recovery, and spinal evoked potentials were evaluated in some dogs. Historical controls were used from a previous canine study with identical inclusion and exclusion criteria. Results of this study are encouraging. No adverse effects were noted with intravenous injection of PEG or PEG-like polymers. Significant improvements in nociception, proprioception, ambulation, and bladder control were noted in the PEG treated dogs. Based on these preliminary findings, the researchers suggest intravenous polymer injections as a possibility for standard care in the treatment of acute
SCI. A larger randomized, double-blinded, placebo controlled clinical study is needed to further evaluate the therapeutic outcome. LACTATE IN ABDOMINAL SEPSIS Definitive diagnosis of abdominal sepsis is dependent upon positive bacterial culture. However, this result is not available to guide emergent therapy. Previously, cytology of abdominal effusion was found to be less than 87% accurate in differentiating septic from non-septic abdominal effusion. Therefore, a venous blood to peritoneal fluid lactate difference (VBPF) was evaluated for its accuracy in distinguishing septic from non-septic conditions.2
Also In This Issue Behavior, 3 Social Play in Birds Impulsive Behavior
Cardiology, 4 Pericardial Effusion
Dermatology, 5 Tacrolimus Ointment for Atopic Dermatitis
Diagnostic Imaging, 5 MRI of Splenic and Hepatic Lesions
Nephrology, 6 Catheter-Associated Urinary Tract Infections
Oncology, 7 Paclitaxel Chemotherapy in Dogs
Surgery – Soft Tissue, 8 Surgical Treatment of Esophageal Sarcoma
“Significant improvements in nociception, proprioception, ambulation, and bladder control were noted in the PEG treated dogs.” Abdominal sepsis is known to elevate lactate levels in blood and peritoneal fluid. However, non-septic inflammatory conditions, such as neoplasia, pancreatitis, and cardiac disease, may also cause lactate elevations. In a small study using 19 dogs and 18 cats presenting with abdominal effusion, researchers found both the
median blood and peritoneal fluid lactate concentrations to be higher in dogs and cats with septic effusions. However, VBPF lactate values were found to be more accurate than cytology in diagnosing septic peritonitis in dogs. When blood-tofluid lactate value was less than –2.0 mmol/L, there was a 63% sensitivity, 100% specificity, and 84% accuracy for detecting septic abdominal effusions in dogs. When blood to fluid lactate levels were less than –1.5 mmol/L, there was an 88% sensitivity, 91% specificity, and 90% accuracy. In addition, a peritoneal fluid lactate concentration of more than 2.5 mmol/L was found to have a 100% sensitivity and 91% specificity. Therefore, evaluation of blood and peritoneal fluid lactate levels may be useful adjunctive tests in the emergency diagnosis of septic peritonitis in dogs.
Advances
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RELATIVE ADRENAL INSUFFICIENCY Recent studies have suggested the existence of transient adrenal dysfunction in certain sub-populations of critically ill humans. This relative adrenal insufficiency (RAI) most often presents as fluid and vasopressor resistant septic shock. Cytokines and inflammatory peptides are believed to inhibit normal function of the hypophysealpituitary-adrenal axis. RAI has been defined as disassociation of plasma cortisol and ACTH levels, but the correct interpretation of ACTH stimulation tests is controversial. It is known that glucocorticoids are critical for cellular function in health and disease. However, previous studies using “high dose” steroid administration did not improve long-term survival but resulted in detrimental side effects in some patients. Newer studies illustrate beneficial effects of “low dose” (200 to 300 mg) hydrocortisone administration in the significant reduction of morbidity and mortality of septic human patients. Results of the few available companion animal studies are inconclusive. One small canine study failed to document the existence of RAI in a population of ICU patients suffering from a variety of acute and chronic illnesses. However, other animal models, including a cat lymphoma study, have also
suggested that RAI may indeed be a clinical entity, and low dose corticosteroids may have a positive effect. In their article, Drs. Martin and Groman review the pertinent human and veterinary RAI literature.3 They suggest RAI be considered a differential diagnosis in hypotensive patients failing to respond to appropriate, aggressive fluid and vasopressor therapy. In addition, they advocate further research in adrenal function in critically ill veterinary patients and recommend controlled, prospective, randomized trials to evaluate the efficacy of low dose glucocorticoid supplementation on patient outcome. FAST BLUNT ABDOMINAL TRAUMA ASSESSMENT In recent years, the Focused Abdominal Sonogram for Trauma, or FAST, has become a popular tool in the assessment of human blunt trauma patients for free abdominal fluid. Its high sensitivity, specificity, and minimal sonographic training requirements have made it useful during initial assessment and stabilization. Evaluation of a modified FAST protocol was undertaken in 100 dogs examined within 24 hours of motor vehicle accident.4 Examiners underwent 2 hours of didactic training on ultrasound physics and performed 5 FAST evaluations on normal dogs prior to examining trauma dogs. In
each FAST exam, 2 sonographic views were taken at 4 sites: subxyphoid; cranial to the pelvis; and right and left flanks caudal to the ribs. All dogs were placed in either left or right lateral recumbency and examined for the presence of free abdominal fluid accumulation. Still images documenting all 8 views were later evaluated by a board-certified radiologist. Most examinations required less than 10 minutes. Positive FAST results were obtained in 45 dogs, and 40 had abdominocentesisdocumented evidence of either hemoabdomen (38 dogs) or uroperitoneum (2 cases). Five dogs with positive FAST tests did not undergo abdominocentesis for confirmation. The view most commonly positive was the gravity-dependent, lateral view. Dogs with positive FAST results had statistically significant elevations in heart rate and lactate levels and lower packed cell volume and total solids levels than patients with negative FAST results. Only one false-negative and one false-positive result was suspected after review of all still images by the boarded radiologist. Although this study lacked a healthy control group, the authors feel the FAST protocol allows for the noninvasive, rapid, accurate diagnosis of free abdominal fluid in blunt trauma dogs by emergency clinicians with minimal sonographic training.
Advances REFERENCES 1. Laverty PH, Leskover A, Breur G, et al. A preliminary study of intravenous surfactants in paraplegic dogs: Polymer therapy in canine clinical SCI. J Neurotrauma 2004; 21:1767-1777. 2. Levin GM, Bonczynski JJ, Ludwig LL, et al. Lactate as a diagnostic test for septic peritoneal effusions in dogs and cats. J Am Anim Hosp Assoc 2004;40:364-371. 3. Martin LG, Groman RP. Relative adrenal insufficiency in critical illness. J Vet Emer Crit Care Soc 2004;14:149-157. 4. Boysen SR, Rozanski EA, Tidwell AS, et al. Focused abdominal sonogram for trauma (FAST) in 100 dogs involved in motor vehicle accidents. J Am Vet Med Assoc 2004;225:1198-204.
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Advances in Small Animal Medicine and Surgery Future Directions in Veterinary Critical Care Alisa Reniker, DVM Diplomate, American College of Veterinary Emergency and Critical Care Clinical Assistant Professor College of Veterinary Medicine University of Missouri Columbia, MO 65211 INTRAVENOUS SURFACTANTS IN PARAPLEGIC DOGS Researchers are currently investigating the use of polyethylene glycol (PEG) and PEG-like polymers as adjunctive therapies for acute spinal cord injury (SCI) in dogs.1 These compounds have surfactant effects and act as membrane sealants. This effect has been previously studied after crushed nerve or spinal cord injury in laboratory animals. Dogs with severe SCI and no deep nociception after Hansen type I intervertebral disk extrusion served as a naturally occurring animal model to evaluate efficacy and safety of PEG. Each dog received complete physical and neurological examinations, myelography, and surgical decompression with removal of extruded disc material. Additionally, dogs received intravenous injections of methylprednisolone and PEG. Neurologic examinations were repeated using a scoring system to evaluate recovery, and spinal evoked potentials were evaluated in some dogs. Historical controls were used from a previous canine study with identical inclusion and exclusion criteria. Results of this study are encouraging. No adverse effects were noted with intravenous injection of PEG or PEG-like polymers. Significant improvements in nociception, proprioception, ambulation, and bladder control were noted in the PEG treated dogs. Based on these preliminary findings, the researchers suggest intravenous polymer injections as a possibility for standard care in the treatment of acute
SCI. A larger randomized, double-blinded, placebo controlled clinical study is needed to further evaluate the therapeutic outcome. LACTATE IN ABDOMINAL SEPSIS Definitive diagnosis of abdominal sepsis is dependent upon positive bacterial culture. However, this result is not available to guide emergent therapy. Previously, cytology of abdominal effusion was found to be less than 87% accurate in differentiating septic from non-septic abdominal effusion. Therefore, a venous blood to peritoneal fluid lactate difference (VBPF) was evaluated for its accuracy in distinguishing septic from non-septic conditions.2
Also In This Issue Behavior, 3 Social Play in Birds Impulsive Behavior
Cardiology, 4 Pericardial Effusion
Dermatology, 5 Tacrolimus Ointment for Atopic Dermatitis
Diagnostic Imaging, 5 MRI of Splenic and Hepatic Lesions
Nephrology, 6 Catheter-Associated Urinary Tract Infections
Oncology, 7 Paclitaxel Chemotherapy in Dogs
Surgery – Soft Tissue, 8 Surgical Treatment of Esophageal Sarcoma
“Significant improvements in nociception, proprioception, ambulation, and bladder control were noted in the PEG treated dogs.” Abdominal sepsis is known to elevate lactate levels in blood and peritoneal fluid. However, non-septic inflammatory conditions, such as neoplasia, pancreatitis, and cardiac disease, may also cause lactate elevations. In a small study using 19 dogs and 18 cats presenting with abdominal effusion, researchers found both the
median blood and peritoneal fluid lactate concentrations to be higher in dogs and cats with septic effusions. However, VBPF lactate values were found to be more accurate than cytology in diagnosing septic peritonitis in dogs. When blood-tofluid lactate value was less than –2.0 mmol/L, there was a 63% sensitivity, 100% specificity, and 84% accuracy for detecting septic abdominal effusions in dogs. When blood to fluid lactate levels were less than –1.5 mmol/L, there was an 88% sensitivity, 91% specificity, and 90% accuracy. In addition, a peritoneal fluid lactate concentration of more than 2.5 mmol/L was found to have a 100% sensitivity and 91% specificity. Therefore, evaluation of blood and peritoneal fluid lactate levels may be useful adjunctive tests in the emergency diagnosis of septic peritonitis in dogs.
Advances
Page 2
RELATIVE ADRENAL INSUFFICIENCY Recent studies have suggested the existence of transient adrenal dysfunction in certain sub-populations of critically ill humans. This relative adrenal insufficiency (RAI) most often presents as fluid and vasopressor resistant septic shock. Cytokines and inflammatory peptides are believed to inhibit normal function of the hypophysealpituitary-adrenal axis. RAI has been defined as disassociation of plasma cortisol and ACTH levels, but the correct interpretation of ACTH stimulation tests is controversial. It is known that glucocorticoids are critical for cellular function in health and disease. However, previous studies using “high dose” steroid administration did not improve long-term survival but resulted in detrimental side effects in some patients. Newer studies illustrate beneficial effects of “low dose” (200 to 300 mg) hydrocortisone administration in the significant reduction of morbidity and mortality of septic human patients. Results of the few available companion animal studies are inconclusive. One small canine study failed to document the existence of RAI in a population of ICU patients suffering from a variety of acute and chronic illnesses. However, other animal models, including a cat lymphoma study, have also
suggested that RAI may indeed be a clinical entity, and low dose corticosteroids may have a positive effect. In their article, Drs. Martin and Groman review the pertinent human and veterinary RAI literature.3 They suggest RAI be considered a differential diagnosis in hypotensive patients failing to respond to appropriate, aggressive fluid and vasopressor therapy. In addition, they advocate further research in adrenal function in critically ill veterinary patients and recommend controlled, prospective, randomized trials to evaluate the efficacy of low dose glucocorticoid supplementation on patient outcome. FAST BLUNT ABDOMINAL TRAUMA ASSESSMENT In recent years, the Focused Abdominal Sonogram for Trauma, or FAST, has become a popular tool in the assessment of human blunt trauma patients for free abdominal fluid. Its high sensitivity, specificity, and minimal sonographic training requirements have made it useful during initial assessment and stabilization. Evaluation of a modified FAST protocol was undertaken in 100 dogs examined within 24 hours of motor vehicle accident.4 Examiners underwent 2 hours of didactic training on ultrasound physics and performed 5 FAST evaluations on normal dogs prior to examining trauma dogs. In
each FAST exam, 2 sonographic views were taken at 4 sites: subxyphoid; cranial to the pelvis; and right and left flanks caudal to the ribs. All dogs were placed in either left or right lateral recumbency and examined for the presence of free abdominal fluid accumulation. Still images documenting all 8 views were later evaluated by a board-certified radiologist. Most examinations required less than 10 minutes. Positive FAST results were obtained in 45 dogs, and 40 had abdominocentesisdocumented evidence of either hemoabdomen (38 dogs) or uroperitoneum (2 cases). Five dogs with positive FAST tests did not undergo abdominocentesis for confirmation. The view most commonly positive was the gravity-dependent, lateral view. Dogs with positive FAST results had statistically significant elevations in heart rate and lactate levels and lower packed cell volume and total solids levels than patients with negative FAST results. Only one false-negative and one false-positive result was suspected after review of all still images by the boarded radiologist. Although this study lacked a healthy control group, the authors feel the FAST protocol allows for the noninvasive, rapid, accurate diagnosis of free abdominal fluid in blunt trauma dogs by emergency clinicians with minimal sonographic training.
Advances REFERENCES 1. Laverty PH, Leskover A, Breur G, et al. A preliminary study of intravenous surfactants in paraplegic dogs: Polymer therapy in canine clinical SCI. J Neurotrauma 2004; 21:1767-1777. 2. Levin GM, Bonczynski JJ, Ludwig LL, et al. Lactate as a diagnostic test for septic peritoneal effusions in dogs and cats. J Am Anim Hosp Assoc 2004;40:364-371. 3. Martin LG, Groman RP. Relative adrenal insufficiency in critical illness. J Vet Emer Crit Care Soc 2004;14:149-157. 4. Boysen SR, Rozanski EA, Tidwell AS, et al. Focused abdominal sonogram for trauma (FAST) in 100 dogs involved in motor vehicle accidents. J Am Vet Med Assoc 2004;225:1198-204.
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