Patient assessment and monitoring (Proceedings)
The ability to accurately assess your patient is a key feature of success for a veterinarian. Although the importance of proper patient assessment is applicable to all fields of veterinary medicine, it is most apparent for the emergency/critical care clinician who may need to make rapid decisions based on observations obtained in a very short period of time. Proper patient assessment is based on both 'the big picture' and subtle details that can be identified with careful observation and a thorough physical examination.
Animals presenting through the emergency room should be assessed immediately to determine if they are hemodynamically stable or if they require emergent therapy. Helpful indicators of cardiovascular instability include altered mentation, collapse, tachycardia, tachypnea, weak or thready femoral pulses, and lactic acidosis. Once therapy has been initiated, it is also critical to re-assess the critical pet for response to therapy. If these parameters fail to normalize following treatment for shock, then diagnostics need to be performed on an emergent basis in order to identify the underlying disease process. If the hemodynamic status improves in response to therapy, it is also important to be vigilant and re-assess the patient regularly. If therapy for shock is successful, for example, it is imperative that the clinician decide on a treatment plan, then re-assess the animal regularly to see if the plan is adequate. Ongoing tachycardia and the development of tachycardia are both early signs of impending cardiovascular decompensation. Early detection of these changes and subsequent interventions will increase the likelihood of a positive outcomeMonitoring
The purpose of the heart is to deliver oxygenated blood from the heart to the peripheral tissues. Oxygen delivery (DO2) is a function of cardiac output (CO), and arterial oxygen content (CaO2).
DO2 = CO x CaO2
Although oxygen delivery and cardiac output are difficult to measure clinically, evaluation of certain parameters such as heart rate, arterial blood pressure and central venous pressure can help assess the state of the cardiovascular system.
Heart rate can be monitored by palpating the chest wall, feeling the arterial pulse, by auscultation, or by performing an electrocardiogram (ECG). Since CO = HR x SV, it is clear that changes in heart rate can affect oxygen delivery to tissues. Causes for tachycardia are many and include hypovolemia, shock, pain, anxiety, primary cardiac disease, and cardiac arrhythmias. Bradycardia may occur with high vagal tone, cardiac diseases including sick sinus syndrome, in cats with shock, and in animals in which cardiac arrest is imminent. Animals that present to the emergency room with tachycardia should be connected to a continuous ECG machine to identify the type of arrhythmia (such as ventricular tachycardia), and to observe response to therapy. If an arrhythmia is documented while connected to an ECG machine, a 6-lead ECG should be printed for further categorization of the arrhythmia. In many instances, continuous ECG monitoring is implemented in hospitalized animals with critical illness, severely depressed mentation, diseases known to predispose to arrhythmias, such as the post operative dog with gastric torsion and in dogs with cardiac arrhythmias necessitating anti-arrhythmic therapy.