Tiêu đề NCM 112 RLE MIDTERMS ✅

RD PRS Wound Care: Chest Tube Thoracostomy Study... Chest Tube Thoracostomy: Wound Care Study Guide.pdf Thoracentesis from Clinical Key: Thoracentesis - ClinicalKey for N... WEEK 3 - BASIC NURSING PROCEDURES 12 leading ECG.mp4 - transcript on the table PRS Coronary heart disease remains a leading cause of mortality worldwide. Prompt recognition and treatment of acute coronary syndromes, such as ST-segment elevation myocardial infarction (STEMI) and non-STEMI acute coronary syndrome, can reduce and prevent cardiac arrest. Electrocardiography, one of the most valuable and frequently used diagnostic tools, displays the heart's electrical activity as waveforms. Impulses moving through the heart's conduction system create electrical currents that can be monitored on the body's surface. Electrodes attached to a patient's skin can detect these electrical currents and transmit them to an instrument that produces a record of cardiac activity, known as an electrocardiogram (ECG). An ECG can be used to identify myocardial ischemia and infarction, rhythm and conduction disturbances, chamber enlargement, electrolyte imbalances, and drug toxicity. A standard 12-lead ECG uses a series of electrodes placed on the extremities and chest wall to assess a patient's heart from 12 different views (leads). The 12 leads consist of: - 3 standard bipolar limb leads (designated I, II, III) - 3 unipolar augmented limb leads (aVR, aVL, aVF); - 6 unipolar precordial leads (V1 to V6). The limb leads and augmented leads show the heart from the frontal plane. The precordial leads show the heart from the horizontal plane. UNDERSTANDING ECG LEADS Each of the leads on a 12-lead ECG views the heart from a different angle. These illustrations show the direction of electrical activity (depolarization) monitored by each lead and the 12 views of the heart. Views reflected on a 12- lead ECG Lead View of the heart Standard limb leads (bipolar) I Lateral wall II Inferior wall III Inferior wall Augmented limb leads (unipolar) aVR No specific view aVL Lateral wall aVF Inferior walll Precordial or chest leads (unipolar) V1 Septal wall V2 Septal wall V3 Anterior wall V4 Anterior wall V5 Lateral wall V6 Lateral wall ECG machine measures and averages the differences among the electrical potential of the electrode sites for each lead and graphs them over time. This process creates the standard ECG complex, made up of P-QRS-T. - P wave represents atrial depolarization; - QRS complex, ventricular depolarization; - T wave, ventricular repolarization. REVIEWING ECG WAVEFORMS AND COMPONENTS An ECG waveform has three basic components: the P wave, QRS complex, and T wave. These elements can be further divided into the PR interval, J point, ST segment, U wave, QT interval. P wave and PR interval The P wave represents atrial depolarization. The PR interval represents the time it takes an impulse to travel from the atria through atrioventricular nodes and the bundle of His. The PR interval is measured from beginning of the P wave to the beginning of the QRS complex. QRS complex QRS complex represents ventricular depolarization (the time it takes for the impulse to travel through the bundle branches to the Purkinje fibers). The Q wave, when present, appears as the first negative deflection in the QRS complex; R wave appears as the first positive deflection. The S wave appears as the second negative deflection or first negative deflection after the R wave. J point and ST segment Marking the end of the QRS complex, the J point also indicates the beginning of the ST segment. The ST segment represents part of ventricular repolarization T wave and U wave The T wave usually follows the same deflection pattern as the O wave and represents ventricular repolarization. The U wave follows the T wave but isn't always seen; it is seen most frequently during bradycardia in leads V2 and V3. QT interval The QT interval represents ventricular depolarization and repolarization. It extends from the beginning of the QRS complex to the end of the T wave.