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Ekg pulseless electrical activity11/25/2023 Regularity of the complexes - are the complexes regular? Uniformity - do all the complexes look the same? Morphology - identify each part of the complex To help recognise and analyse an arrhythmia the PQRS complex must be looked at in a systematic way - look for: Both of which, if severe, can compromise CO and subsequently tissue O 2 delivery. However, the ECG provides valuable information regarding heart rate and rhythm and allows for the diagnosis and treatment of cardiac arrhythmias and conduction abnormalities. The ECG should never be used as a sole indicator for cardiac function. CO and tissue perfusion can be reduced even if the ECG appears normal. In order for the heart muscles to contract they must first receive an electrical stimulus and it is this electrical activity that is detected by an ECG.ĮCG monitoring does not supply any information regarding the mechanical function of the heart and does not directly assess CO. To correct hypotension the cause of the hypotension has to be identified (Figure 1).īlood pressure monitoring can be performed using either non-invasive techniques, e.g., oscillometric and Doppler, or invasive techniques, e.g., direct arterial catheterisation.Ĭheck anaesthetic depth and avoid excessive depth of anaesthesiaįor the heart to function effectively as a pump it must have a coordinated contraction which pushes blood from the atria down to the ventricles and eventually around the body to perfuse cells and tissue. Hypotension is typically the result of a decrease in the heart rate, stroke volume, systemic vascular resistance, the intravascular fluid volume or a combination of all these components. Severe hypotension can also reduce coronary blood flow, which can lead to cardiac arrhythmias and potential cardiac arrest. This can lead to poor tissue O 2 delivery and, if left untreated, organ failure can ensue. When MAP falls below 60 mmHg, blood flow to the organs can be compromised. Hypotension can be defined as a MAP below 60 mmHg or a systolic arterial pressure of below 90 mmHg. MAP = (cardiac output × systemic vascular resistance) + Central Venous Pressure (CVP)Ĭardiac output = heart rate × stroke volume.ĭuring anaesthesia all animals experience some degree of hypotension. Mean arterial pressure (MAP) is determined by a combination of CO (heart rate, stroke volume), systemic vascular resistance and intravascular fluid volume. The closest measurement we have to assess CO in clinical practice is blood pressure measurement. Instead, methods of monitoring cardiovascular stability, and indirectly CO and tissue perfusion, include 'perfusion parameters', e.g., SpO 2 trace and end-tidal carbon dioxide but also blood pressure (BP) and electrocardiogram (ECG) monitoring. It is invasive and requires the placement of a Swan-Ganz catheter passed from the jugular vein, through the right atrium into the pulmonary artery. Tissue oxygen delivery = oxygen content x cardiac outputĬardiac output = heart rate x stroke volumeĭirect measurement of CO in veterinary patients is rarely performed except in research settings. This is demonstrated in the equation below. Delivery of O 2 to the cells is reliant on adequate carriage of O 2 by the haemoglobin and a good cardiac output (CO) to circulate the oxygenated blood around the body. When the delivery of O 2 fails, the cells switch to anaerobic metabolism which can result in the accumulation of lactic acid and cellular function can be compromised. Under anaesthesia the ultimate goal is to maintain tissue oxygen (O 2) delivery so that metabolism can continue aerobically. Books & VINcyclopedia of Diseases (Formerly Associate).VINcyclopedia of Diseases (Formerly Associate).
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