Critical care surgical techniques

A veterinarian dealing with critical and trauma patients must be proficient with techniques for tracheostomy, thoracostomy tube placement for chest drainage, diagnostic peritoneal lavage, and autotransfusion. The utilization of these techniques may be life-saving in the critical patient. A tracheostomy is indicated in any patient with upper airway obstruction that cannot be managed with supplemental oxygen and/or orotracheal intubation. A tracheostomy tube with an inner cannula is preferred. Tracheostomy tubes should be cleaned at 3- to 4-h intervals, and methods should be employed to decrease thick tracheal secretions and to remove them from the trachea. A patient with a tracheostomy tube should be monitored continuously. A thoracostomy tube is indicated in any patient with large and/or continuous accumulation of air, blood, fluid, or chyle in the pleural space. The thoracostomy tube should be at least the same size as the patient's main stem bronchus. The thoracostomy tube is placed aseptically at the seventh intercostal space at the junction of the upper one third and lower two thirds of the lateral chest wall. Fluid or air may be removed from the chest intermittently with a three-way stopcock attached to the thoracostomy tube and a 60-ml syringe. If continuous drainage is needed, a continuous underwater seal and suction system should be used. Diagnostic abdominal paracentesis and peritoneal lavage are useful techniques in the determination of abdominal trauma, hollow viscus rupture, peritonitis, hepatic trauma, and urinary system trauma. When a multiholed catheter and lavage are used, the accuracy of detecting abdominal trauma is 95 per cent. When only needle paracentesis is used, the accuracy drops to 47 per cent. Abdominal lavage fluid can be analyzed for bacteria, whole blood, white blood cells, free bilirubin, creatinine, blood urea nitrogen, amylase, alkaline phosphatase, and alanine aminotransferase. Large volumes of whole blood recovered from abdominal or thoracic paracentesis can be reinfused into the patient if needed, providing it is not contaminated or markedly hemolyzed. The blood should be collected aseptically into blood bottles or bags. If the bleeding is ongoing or the blood only a few hours old, anticoagulants should be used. If the hemorrhage is several hours old, then clotting and defibrination has already occurred and the blood can be collected into "dry" bags or bottles. Before use, abdominal blood should be analyzed for urine, bile or fecal contamination. Blood collected from the thoracic cavity is much less likely to be contaminated. Autotransfused blood is administered through a standard blood administration set.     

Critical care monitoring.

Critical care monitoring in exotic practice is limited by the small size and the physiologic diversity of many patients. However, many of the principles applied to humans and other mammals can be extrapolated to monitoring in exotic animals. Advances in the monitoring of human patients offer the potential for more practical, low-cost monitoring in critical exotic patients in the future.     

Critical care monitoring.

Small mammals and birds present unique challenges for the clinician in treatment of life-threatening conditions. Numerous books have been written on shock, critical care, and cardiopulmonary resuscitation in small animals. The basic protocols can be adapted for use in small mammals and birds. A general review of the pathophysiology of shock is important to the understanding of fluid therapy plans discussed in this article. Using the general principles of cardiopulmonary-cerebral resuscitation in small animals, protocols are discussed for use in birds and small mammals.     

Critical care of the rabbit.

Emergency and critical care principles are similar for all mammals. However, because they are stressed easily, rabbits require specialized handling techniques. Rabbits must be evaluated efficiently and stabilized quickly before moving into the definitive diagnostic phase of their care. A thorough clinical history, systematic physical examination, and multiple diagnostic tests are ideal, but when a rabbit is in critical condition, emergency stabilization and fluid resuscitation must take priority. Common emergency presentations include gastrointestinal disorders, such as prolonged anorexia, respiratory distress, neoplasia, neurologic symptoms, exposure to toxins, trauma, and urinary tract infections or obstruction.     

Critical care monitoring considerations for the diabetic patient

Diabetes mellitus (DM) is a common endocrine disease encountered in the emergency and critical care setting. The diabetic Ketoacidotic (DKA) animal represents an extreme of the DM patient with regard to hyperglycemia and acid-base and electrolyte derangements. Prompt diagnosis of DKA in a critical patient and rapid initiation of appropriate therapy are necessary for a positive outcome. The steps of treatment, in order of importance, include initiation of intravenous fluid therapy, insulin therapy, electrolyte replacement, and reversal of the metabolic acidosis. The main goals of therapy--including correction of dehydration, electrolyte abnormalities and acidosis via aggressive fluid therapy with electrolyte supplementation and correction of ketoacidosis and hyperglycemia via initiation of insulin therapy--can be achieved if these steps are followed. Because of the severity of metabolic alterations in the DKA animal, frequent and careful monitoring are paramount because they will allow the clinician to tailor treatment to each case.     

Interventional cardiology for the criticalist

Objective – To review indications, procedures, and prognosis for common cardiovascular emergencies requiring intervention in small animals. Etiology – Pericardial effusion, symptomatic bradycardia, and heartworm‐induced caval syndrome are examples of clinical scenarios commonly requiring intervention. Pericardial effusion in small animals occurs most frequently from cardiac neoplasia, idiopathic pericarditis, or congestive heart failure. Indications for temporary pacing include transient bradyarrhythmias, ingestions resulting in chronotropic incompetence, and emergency stabilization of critical bradyarrhythmias. Caval syndrome results from a large dirofilarial worm burden, pulmonary hypertension, and mechanical obstruction of right‐sided cardiac output with resultant hemolysis and organ dysfunction. Diagnosis – The diagnosis of pericardial effusion is suspected from signalment and physical findings and confirmed with cardiac ultrasound. Symptomatic bradycardias often present for syncope and definitive diagnosis derives from an ECG. Caval syndrome is diagnosed upon clinical, hematologic, and ultrasonographic evidence of severe heartworm infestation, cardiovascular compromise, and/or mechanical hemolysis. Therapy – Pericardial effusion is alleviated by pericardiocentesis in the emergency setting, though may require further intervention for long‐term palliation. Temporary transvenous pacing can be performed emergently to stabilize the symptomatic patient with a bradyarrhythmia. Dirofilariasis leading to caval syndrome requires urgent heartworm extraction. Prognosis – The prognosis for pericardial effusion is dependent upon the underlying etiology; the prognosis for cardiac pacing is favorable, and the prognosis for caval syndrome is grave if untreated and guarded to fair if heartworm extraction is performed.     

The history of veterinary cardiology

Throughout civilization, animals have played a pivotal role in the advancement of science and medicine. From as early as 400 BC when Hippocrates recognized that diseases had natural causes, the steadfast advances made by biologists, scientists, physicians and scholars were fueled by timely and important facts and information- much of it gained through animal observations that contributed importantly to understanding anatomy, physiology, and pathology. There have been many breakthroughs and historic developments. For example, William Harvey in the 16th and 17th centuries clarified the importance of the circulatory system, aided by observations in dogs and pigs, which helped to clarify and confirm his concepts. The nineteenth century witnessed advances in physical examination techniques including auscultation and percussion. These helped create the basis for enhanced proficiency in clinical cardiology. An explosion of technologic advances that followed in the 20th century have made possible sophisticated, accurate, and non-invasive diagnostics. This permitted rapid patient assessment, effective monitoring, the development of new cardiotonic drugs, clinical trials to assess efficacy, and multi-therapy strategies. The latter 20th century has marshaled a dizzying array of advances in medical genetics and molecular science, expanding the frontiers of etiologies and disease mechanisms in man, with important implications for animal health. Veterinary medicine has evolved during the last half century, from a trade designed to serve agrarian cultures, to a diverse profession supporting an array of career opportunities ranging from private, specialty practice, to highly organized, specialized medicine and subspecialty academic training programs in cardiology and allied disciplines.     

A practitioner's approach to canine cardiology

This paper is intended to be a guide for the practitioner to the diagnosis, prognosis and treatment of heart disease in the dog. Diagnosis and treatment of heart disease is based on a thorough clinical examination specifically auscultation of the chest and examination of the pulse augmented by radiography and electrocardiography.Cardiology is an exciting subject and recent advances in therapy have improved not only the life expectancy of dogs with heart disease but also the quality of life. The most important factor is to recognize that the problem is cardiac in origin. The elderly animal with a cough and a heart murmur must be examined and investigated thoroughly before assuming that the murmur and cough are connected. Overall incidence of heart disease has been estimated at 11 · 3% with the congenital type accounting for 0 · 5% (Detweiler & Patterson, 1965).Congenital heart disease should be detected early in life, and certainly no later than at presentation of the puppy for primary vaccination, but will only be diagnosed if the puppy is thoroughly auscultated. The more common congenital cardiac defects, in approximate order of incidence, are patent ductus arteriosus, pulmonic stenosis, aortic stenosis, persistent right aortic arch, ventricular septal defect, tetralogy of Fallot and atrial septal defect (Patterson, 1965). Early diagnosis is important as, particularly with patent ductus, surgery performed at an early stage can be curative. Pulmonic stenosis can also be treated surgically and successful treatment of tetralogy of Fallot using cardiopulmonary bypass has been reported (Herrtage, Hall & English, 1983). Septal defects are also amenable to treatment by using cardiopulmonary bypass.Persistent right aortic arch will not cause a heart problem but vomiting will occur in the young dog. Chronic valvular fibrosis with mitral, followed by tricuspid, insufficiencies is the most usual acquired heart disease. It has been estimated that in dogs over eight years old 70% are likely to suffer from valvular heart disease but not necessarily showing clinical signs.     

Critical care of pet birds. Procedures, therapeutics, and patient support.

Critically ill birds must be recognized, accurately assessed, and provided rapid appropriate treatment. This article presents a method of assessment and supportive care for critically ill birds. A problem-oriented approach based on clinical signs is presented, accompanied by suggested diagnostic tests. Techniques used to treat critically ill birds are also discussed.     

New perspectives in cardiology: pharmacodynamic classification of antiarrhythmic drugs

Recent advancements in cardiac pharmacology and physiology have led to the identification of many new antiarrhythmic drugs and a better understanding of basic arrhythmogenic mechanisms. These parallel developments prompted a new nomenclature system for classifying the clinically important antiarrhythmic drugs according to their predominant electrophysiologic actions in cardiac cells. Antiarrhythmic drugs are now grouped into 4 main classes: classes I through IV. Class I agents comprise the standard membrane-stabilizing drugs such as lidocaine, quinidine, and procainamide; newer class I agents include disopyramide, aprindine, tocainide, and flecainide. Class II agents decrease sympathoadrenal excitation of the heart, and the clinically relevant members of this type act through blockade of the cardiac beta 1-adrenergic receptors; propranolol is the prototype. Class III agents selectively prolong the cardiac action potential and refractory period, and bretylium and amiodarone represent this group. Class IV agents are the calcium entry blocking drugs such as verapamil. An understanding of this classification system is essential to the internist and cardiologist who are beset with an emerging array of new antiarrhythmic drugs and affiliated pharmacodynamic terminologies.