Emergency Medicine and Critical Care

Emergency patients present special challenges because their underlying disease processes can cause immediate life-threatening problems that require rapid and aggressive intervention. In addition, the full extent of the animal’s illness, injuries, or toxicity may not be evident for some time after initial presentation. Problems can arise from an acute illness, toxicity, or injury; from a chronic illness that has decompensated; or from an unexpected complication of a concurrent illness. The status of all postoperative patients should be considered critical until life-threatening anesthetic or surgical complications are excluded. The golden rule of emergency medicine is to treat the most life-threatening problems first. When a patient is then stable, it should be closely monitored for progression or resolution of disease and possible complications.

Triage is the art of assigning priority to emergency patients and their problems based on rapid assessment of historical and physical parameters (see Table: Parameters to Evaluate During Triage). Several historical or observed problems warrant transfer of the animal to the treatment area regardless of physical findings. These problems include known or suspected trauma, poisonings, profuse vomiting or diarrhea, urethral obstruction, labored breathing, cardiopulmonary arrest, seizures, loss of consciousness, severe alterations in mental state, acute inability to walk, excessive bleeding, prolapsed organs, potential snake bite, heat prostration, open wounds exposing extensive soft tissue or bone, anemia, burns, dystocia, shock, and disease that may rapidly decompensate such as gastric dilatation and volvulus and allergic reactions.

Diagnostic and therapeutic efforts in emergency situations can be directed by the nature of the trauma. Blunt trauma is commonly associated with thoracic and abdominal bleeding, organ rupture, fractures, and neurologic injuries. Penetrating trauma is typically localized to the path of the penetrating object, which is rarely a straight line. Falling from a height causes long bone and facial bone fractures as well as thoracic and abdominal injuries. A dog bitten by a larger dog can have deep-penetrating bite wounds, spinal injuries, major abdominal and thoracic trauma (even without penetrating wounds), and tracheal rupture from the shearing forces sustained during thrashing motions. Resuscitation of the airway, breathing, and circulation; control of hemorrhage; and pain relief are followed by a careful evaluation of the nervous system, chest, abdomen, integument, and musculoskeletal system.

Cardiac function; intravascular volume; and vascular tone, integrity, and patency are critical to normal circulation. An abnormality in one or more of these components of circulation leads to stimulation of the sympathetic nervous system, which results in compensatory changes to maintain perfusion. The hemodynamic and cellular changes that develop as a result of these abnormalities are called shock. As shock progresses, oxygen and substrate delivery to the tissues becomes insufficient to meet energy requirements for cellular maintenance and repair. If shock progresses and cellular energy demands cannot be met, the ensuing organ failure leads to death. Early recognition of the type and stage of shock is vital to establishing a successful fluid therapy plan; timely intervention with appropriate therapy will prevent or decrease organ injury and/or death.

Anticipation, not reaction, is the key to successful management of critically ill animals. Animals must be effectively treated and actively monitored to detect or prevent organ compromise before organ failure occurs. This often requires aggressive and repeated fluid resuscitation and support throughout the course of definitive therapy.

Ophthalmic emergencies require rapid diagnosis and appropriate and often aggressive therapy for maintenance of vision. It is critical to assess the patient's potential for vision by performing a menace response, dazzle reflex, and direct and consensual pupillary light reflexes (PLRs). A consensual PLR (from the affected to nonaffected eye) is particularly useful when the ocular media is opaque and thus prevents assessment of a direct PLR.

Wound healing is the restoration of the normal anatomic continuity to a disrupted area of tissue. An understanding of the normal process of wound healing is essential to make sound decisions in the management of wounds. Correctly using the principles of wound management helps avoid premature wound closure and its potential complications.

Equine emergencies can be challenging for veterinary practitioners and emotionally charged for owners. There is also the inherent possibility of injury to the owner and veterinarian because of the sheer size of the animal and the “fight or flight” reflexes of an injured horse. Problems can be reduced by educating owners about emergency preparedness and first aid procedures. The most common types of equine emergencies are abdominal pain (colic), trauma, lacerations, and acutely ill foals.