N105: Essentials of Nursing Care - Health Differences

Essentials of Nursing Study Guide

©2017 Achieve Test Prep Page 72 of 160 sends impulses from inter-atrial pathways; there is a slight delay in transmission of impulses to the ventricles. Bundle of His sends ventricular conduction pathways to the right and left bundle branches and purkinje fibers. The fibers terminate in ventricular muscle, stimulating contraction. Cardiac output is when the ventricles contract during systole, where the blood flows out, and the heart muscle relaxes (diastole) allowing ventricles to refill. Contraction and relaxation of the heart is known as the cardiac cycle . Cardiac output is the amount of blood pumped by the ventricles in 1 minute. This is calculated as SV x HR = CO (stroke volume x heart rate equals cardiac output). Stroke volume is the amount of blood that is ejected from the ventricles with each contraction. Cardiac output is affected by: • heart rate • preload (degree the muscle fibers in the ventricle are stretched, which depends on the amount of blood returning to heart from the veins) • contractility • afterload (systemic vasoconstriction which increases the arterial blood pressure) Nursing Procedures • Assessment: include all methods of examination (inspection, palpation, percussion, auscultation); auscultate posterior first, then anterior; inspection of shape, symmetry; spinal alignment; palpate for temperature and skin integrity, bulges, tenderness, movements, thoracic expansion, vocal fremitus (vibration); percuss for asymmetry in percussion sounds, diaphragmatic excursion (movement of the diaphragm) and auscultate using a systematic zigzag pattern • Pulse oximeter : a noninvasive device that measures oxygen saturation (SaO2 or O2 Sat); it measures the amount of hemoglobin in arterial blood. Normal SaO2 is 95-100%, below 70 is life-threatening • Cardiac monitoring: allows continuous observations of the patient’s cardiac rhythm • Diagnostic studies: collect sputum specimens for culture and sensitivity, cytology, and acid- fast bacillus (AFB); a throat culture is when a sample is collected from the oropharynx and 3.4 Physiology of the Cardiovascular System The heart carries deoxygenated blood from the veins and enters the right side of the heart through the superior and inferior venae cava. From there it flows into the right ventricle, which pumps it through to the pulmonary artery and into the lungs for gas exchange. Freshly oxygenated blood returns to the left atrium via the pulmonary veins. From here the blood enters the left ventricle to be pumped out to the systemic circulation through the aorta. The coronary circulation is a network of vessels that supply O2 and blood to the heart itself. The cardiac conduction system is a network of specialized cells and pathways that controls the electrical activity and contractions of the heart. The Sino atrial (SA or Sinus) node initiates impulses conducted thought the heart and results in ventricular contraction. The atrioventricular (AV) node

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