Medical Surgical Nursing Lecture: Emergency Nursing PDF

CRITICAL CARE NURSING (CCN) is a specialized field of nursing focused on caring for patients with life-threatening (actual or potential) problems. These patients require comprehensive care and constant close monitoring. ICU (Intensive Care Unit): A designated unit...

CRITICAL CARE NURSING (CCN) is a specialized field of nursing focused on caring for patients with life-threatening (actual or potential) problems. These patients require comprehensive care and constant close monitoring. ICU (Intensive Care Unit): A designated unit in a hospital where high-dependency, critically ill, and hemodynamically unstable patients are housed. ICU Nurse: A nurse trained with specialized BASIC EQUIPMENT IN THE ICU knowledge to deal with ICU patients. Patient Areas: PHILOSOPHY OF CRITICAL CARE NURSING (CCNAPI) Oxygen Outlets: 3 outlets per bed. Suction Outlets: 3 outlets (gastric, tracheal, Holistic Care Approach: and underwater seal). Focuses on the bio-psycho-social-spiritual Compressed Air Outlets: 2 outlets per bed. nature of human beings and their responses Power Outlets: 16 outlets per bed. to illnesses rather than just the disease Storage: process. Helps maintain the individual patient's Bedside storage for personal belongings identity and dignity. care supplies Emphasizes preventive care, risk factor linen and toiletries modification, and education to reduce includes locking drawers and cabinets if future patient admissions to acute care syringes or pharmaceuticals are stored at facilities. the bedside. Organizational Commitment: Additional Equipment: The Critical Care Nurses of the Philippines, Hooks and devices for hanging Inc. (CCNAPI) is dedicated to promoting infusions/blood bags health and welfare for national multi-channel invasive monitors development. ventilators Supports professional and personal growth infusion pumps and development. portable X-ray unit Committed to ideals of service, equality, fluid and bed warmers justice, and social progress. portable lights defibrillators PRINCIPLES OF CRITICAL CARE NURSING anesthesia machines Anticipatory Nursing Care difficult airway management equipment Early Detection and Prompt Action Emergency Alarm: Expertise Supportive Care Communication and Collaborative A cardiac arrest/emergency alarm button Practice at every bedside, with automatic alerts to Preservation of Patient’s Physiological the hospital telecommunications center, Defenses central nursing station, ICU conference Prevention of Infection room, staff lounge, and on-call rooms. Crisis Intervention Stress Reduction ADMITTING PATIENT IN THE ICU: Ethical Principles PREARRIVAL AND ADMISSION QUICK CHECK ORGANIZATION OF ICU ASSESSMENTS Prearrival Assessment: 1|E M E R G E N C Y N U R S I N G | L E S S O N 1 JADE B. BURI 1. Abbreviated Report on Patient: ✓ General communication, coping styles, ✓ Age anxiety and stress, expectations of ✓ Gender critical care unit, current stresses, family ✓ chief complaint needs. ✓ diagnosis 4. Spirituality: ✓ pertinent history ✓ Faith/spiritual preference, healing ✓ physiological status practices. ✓ invasive devices 5. Physical Assessment: ✓ equipment ✓ Nervous system, cardiovascular system, ✓ status of laboratory/diagnostic tests. respiratory system, renal system, 2. Room Setup: gastrointestinal system, endocrine, ✓ Complete room setup hematologic, and immune systems, ✓ including verification of proper integumentary system. equipment functioning. ONGOING ASSESSMENT TEMPLATE (BODY Admission Quick Check Assessment: SYSTEMS AND ASSESSMENT PARAMETERS) 1. General Appearance: Consciousness level. 1. Nervous System: 2. Airway: Patency and position of artificial - LOC, pupils, motor strength, blood airway (if present). pressure, heart rate and rhythm, heart 3. Breathing: Quantity and quality of sounds, capillary refill, peripheral pulse, respirations, breath sounds, presence of patency of IVs, hemodynamic pressures spontaneous breathing. and waveforms, respiratory rate, breath 4. Circulation and Cerebral Perfusion: ECG sounds, etc. (rate, rhythm, and ectopy), blood pressure, 2. Cardiovascular System: peripheral pulses, capillary refill, skin color, - Heart rate, rhythm, ECG, blood temperature, moisture, presence of pressure, cardiac output data, etc. bleeding, level of consciousness, 3. Respiratory System: responsiveness. - Respiratory rate and rhythm, breath 5. Chief Complaint: Primary body system and sounds, color and amount of secretions, associated symptoms. etc. 6. Drugs and Diagnostic Tests: Prior drugs, 4. Renal System: current medications, review of diagnostic - Intake and output, color and amount of test results. urinary output, BUN/creatinine values, 7. Equipment: Patency of vascular and etc. drainage systems, functioning and labeling 5. Gastrointestinal System: of all connected equipment, and allergies. - Bowel sounds, contour of abdomen, color and amount of secretions, etc. Comprehensive Admission Assessment: 6. Endocrine, Hematologic, and Immunologic 1. Past Medical History: Systems: ✓ Medical conditions and surgical - Electrolyte and glucose values, CBC procedures. and coagulation values, WBC with ✓ Psychiatric/emotional problems, differential count, etc. hospitalizations. 7. Integumentary System: ✓ Medications (prescription, over-the- - Color and temperature of skin, counter, illicit drugs) and time of last intactness of skin, areas of redness, etc. dose. 8. Pain/Discomfort: ✓ Allergies, review of body systems. - Assessed in each system. 2. Social History: 9. Psychosocial System: ✓ Age, gender, ethnic origin, height, - Response to interventions, mental status weight, highest educational level, and behavioral responses, ability to occupation, marital status, primary communicate needs and participate in family members/significant others, care, sleep patterns, etc. religious affiliation. PHYSIOLOGIC EFFECTS OF AGING (BODY ✓ Advance Directive and Durable Power SYSTEMS AND EFFECTS) of Attorney for Health Care. ✓ Substance use (alcohol, drugs, 1. Nervous System: caffeine, tobacco), domestic abuse, or - Diminished hearing and vision, short- vulnerable adult screen. term memory loss, altered motor 3. Psychosocial Assessment: coordination, decreased muscle tone and strength, slower response to verbal 2|E M E R G E N C Y N U R S I N G | L E S S O N 1 JADE B. BURI  and motor stimuli, increased sensitivity to sedation, etc. 2. Cardiovascular System: - Increased effects of atherosclerosis, decreased stroke volume, decreased myocardial compliance, increased workload of heart, etc. 3. Respiratory System: - Decreased compliance and elasticity, decreased vital capacity, increased residual volume, etc. CLASSIFICATION OF SHOCK 4. Renal System: - Decreased glomerular filtration rate, 1. Primary (Initial Shock) increased risk of fluid and electrolyte 2. Secondary (True Shock) imbalances, etc. ✓ True Shock (Circulatory Shock): A 5. Gastrointestinal System: circulatory imbalance between oxygen - Increased presence of dentition supply and oxygen requirements at the problems, decreased intestinal mobility, cellular level. altered nutritional states, etc. 3. Anaphylactic Shock: Type I immunologic 6. Endocrine, Hematologic, and Immunologic reaction. Systems: ETIOLOGICAL CLASSIFICATION - Increased incidence of diabetes, thyroid disorders, anemia, decreased 1. Hypovolemic Shock antibody response, etc. 2. Cardiogenic Shock 7. Integumentary System: 3. Septic Shock - Decreased skin turgor, increased capillary fragility, decreased elasticity, Other Types: etc. 1. Traumatic Shock 8. Miscellaneous: 2. Neurogenic Shock - Altered pharmacokinetics and 3. Hypoadrenal Shock pharmacodynamics, decreased range of motion of joints and extremities, etc. TYPES OF SHOCK 9. Psychosocial System: - Difficulty falling asleep, fragmented 1. Cardiogenic Shock sleep patterns, increased incidence of ✓ Intracardiac Causes: Related to issues depression and anxiety, cognitive within the heart itself, such as impairment, etc myocardial infarction or valvular heart disease. SHOCK OVERVIEW ✓ Extracardiac Causes: Related to conditions outside the heart, like Shock is a life-threatening situation due to poor pulmonary embolism or tension tissue perfusion with impaired cellular pneumothorax. metabolism, leading to serious 2. Hypovolemic Shock pathophysiological abnormalities. If untreated, ✓ Caused by a significant loss of blood shock has a mortality rate of 20%. volume due to hemorrhage, Bailey and Love: Shock results from poor dehydration, or burns. tissue perfusion with impaired cellular 3. Distributive Shock metabolism. ✓ Characterized by severe peripheral Davidson's: Shock is a clinical syndrome that vasodilation leading to inadequate develops from critical impairment of tissue tissue perfusion despite normal or perfusion due to acute circulatory failure. increased cardiac output. Schwartz's: Shock is defined as the a. Sepsis: A systemic infection causing inadequate delivery of oxygen and widespread inflammation and nutrients necessary to maintain normal vasodilation. tissue and cellular function. b. Neurogenic (Spinal Shock): Caused Kumar and Parrillo (1995): Shock is a state by spinal cord injury leading to loss where profound and widespread reduction of sympathetic tone and of effective tissue perfusion leads to vasodilation. reversible, and if prolonged, irreversible c. Adrenal Insufficiency: Inadequate cellular injury. production of cortisol and 3|E M E R G E N C Y N U R S I N G | L E S S O N 1 JADE B. BURI  aldosterone, leading to hypotension and shock. d. Anaphylaxis: A severe allergic reaction causing widespread vasodilation and increased capillary permeability. Blood Pressure (BP) Regulation in Shock BP = CO × SVR BP: Blood Pressure CO: Cardiac Output SVR: Systemic (Peripheral) Vascular Resistance If blood pressure is low in a shock state, it indicates that either: ✓ CO is low: The heart is not pumping enough blood, leading to decreased cardiac output. ✓ SVR is low: There is reduced vascular resistance, often seen in distributive shock types like sepsis or anaphylaxis. 4|E M E R G E N C Y N U R S I N G | L E S S O N 1 JADE B. BURI  SHOCK - Orthostatic vital signs may be normal in hypovolemic individuals, or normal The common denominator in all forms of individuals may exhibit orthostatic shock is inadequate capillary perfusion. changes; so use clinical judgment and Shock is characterized by inadequate tissue base treatment on symptoms. Alcohol perfusion and cellular ingestion, a meal, increased age, hypofunction/hypoxia. antihypertensives, etc., may cause Total body cellular metabolism is orthostatic changes in BP and pulse in malfunctional, usually by inadequate the absence of hypovolemia. delivery of oxygen to meet cellular needs Tachycardia: Usually present but may not and occasionally of inability of cells to utilize be, especially in the presence of oxygen (methemoglobinemia, carbon diaphragmatic irritation, which causes monoxide poisoning). vagal stimulation in neurogenic shock. Shock has been recognized for over 100 Hypoperfusion: Including decreased urine years, yet a clear definition is still not output, decreased mentation, cool established. The definition of shock varies extremities, mottling, etc. over time and has different meanings - Goal of resuscitation is to maintain urine depending on the etiological and output between 30 and 60 ml/hr. pathogenetic factors that caused it. HYPOVOLEMIC SHOCK CLASSIFIED BY ETIOLOGY is present when a marked reduction in oxygen delivery results from diminished (BY MARK A. GRABER, MD) cardiac output secondary to inadequate volume of whole blood. Departments of Family Medicine and Emergency Medicine, University of Iowa Pathophysiology: College of Medicine. Peer Review Status: Externally Peer Reviewed by Mosby. When our body loses a lot of blood or fluids, like from heavy bleeding, burns, or severe 1. Hypovolemic shock: from volume loss (e.g., vomiting or diarrhea. dehydration, blood loss, burns). Since there is a lot of blood or fluids loss 2. Distributive shock: based on loss of vascular happens in our body, the heart can’t pump tone (e.g., anaphylactic, septic, out enough blood throughout our body bacteremic, toxic, neurogenic shock). organs 3. Cardiogenic shock: based on pump failure Since our body organs can’t get enough (e.g., acute myocardial infarction, blood, our body’s organs don’t get enough ventricular septal defect rupture, papillary oxygen, which is like running out of fuel. muscle rupture, ventricular aneurysm, Without oxygen, your organs can’t work severe aortic stenosis, arrhythmias, properly, and your body starts to struggle to trauma—tension pneumothorax, keep things running smoothly. pericardial tamponade, cardiac contusion). To compensate, your body tries to adjust by: 4. Dissociative shock: based on the inability of a. Speeding up your heart rate to try to RBCs to deliver oxygen (e.g., pump what little blood is left. methemoglobinemia, carbon monoxide b. Narrowing your blood vessels to direct poisoning). blood to the most important organs, like Most common clinical signs: the brain and heart, which is why your skin might turn pale and cool. Hypotension: Blood pressure drop is a late c. Breathing faster to get more oxygen finding. into your system. - An orthostatic systolic decrease of 10 to d. Decreasing your urine output, because 20 mm Hg or an increase in pulse of 15 your body tries to hold onto as much beats/min is considered "significant." fluid as possible. - Take orthostatic vital signs recumbent and after standing for 1 to 2 minutes. Causes 1|E M E R G E N C Y N U R S I N G | LESSON 2 JADE B.BURI  ✓ External bleeding. especially when the host's defenses are ✓ Internal bleeding. weakened due to prolonged and severe ✓ The loss of a large amount of plasma due infections. to extensive burns. Septic shock is sepsis with hypoperfusion ✓ The loss of fluids and electrolytes after and hypotension that are refractory to fluid prolonged and severe diarrhea, therapy. When bacteremia causes critical vomiting. reductions in tissue perfusion, septic shock ✓ An internal loss of fluids due to pleuritis or ensues. peritonitis, acute pancreatitis. Pathophysiology: Note: The last three causes are sometimes Happens when the blood vessels in your named oligemic shock. body lose their normal tone and become Clinical signs: too relaxed or leaky. This leads to a problem where blood can’t effectively circulate to ✓ Hypotension your organs and tissues, causing them to be ✓ Tachycardia deprived of oxygen and nutrients. ✓ Tachypnea Normally, your blood vessels stay slightly ✓ Oliguria tight to keep blood moving where it’s ✓ Anxious needed. In distributive shock, something ✓ Skin is pale and cool (like an infection) causes these vessels to ✓ Often, the patient may experience suddenly relax too much. nausea and vomiting Because the blood vessels are too relaxed, ✓ Can be restless or comatose blood starts pooling in certain parts of your body instead of being pumped evenly to Laboratory determination: important areas like the brain, heart, and Arterial blood gases: pH is considered kidneys. This means your organs don’t get normal (7.35-7.45), PaCO2 is 35-45 mm Hg. If enough blood to function properly. pH < 7.35, this is associated with a normal or With blood not circulating properly, your lower PaCO2 (metabolic acidosis). blood pressure drops. In vomiting caused by stenosis of the pyloric When your organs (like the brain and part of the stomach: alkalosis. kidneys) don’t get enough oxygen-rich Serum electrolytes: In hemorrhagic shock, blood, they start to suffer. Over time, this they are near normal; in diarrhea, potassium can cause serious damage, and multiple (K) decreases; in vomiting, sodium (Na) organs can start to fail if the shock isn’t decreases; in pancreatitis, calcium (Ca) treated quickly. and potassium (K) decrease. In cases like septic shock (a type of Creatinine: Useful as an indicator of renal distributive shock caused by an infection), function. bacteria release toxins that further mess up your blood circulation. Your immune Treatment and management of hypovolemic system’s response to these toxins can also shock principles: make things worse, causing inflammation and more blood vessel problems. Monitoring of blood pressure, urination, Distributive shock is like a problem with the breathing function, and heart rate (HR). plumbing in your body. Blood isn’t flowing Replacement of blood volume (e.g., where it should, which causes your organs Ringer's lactate, solutions similar to plasma to struggle and eventually leads to serious in electrolyte composition, starch or gelatin damage if not corrected. solution, erythrocyte mass in cases of bleeding). Causes: Supplemental oxygen. After resuscitation: surgical manipulations, Septic shock is often caused by hospital- interventional radiology, endoscopy, and acquired gram-negative bacilli and drug therapy. typically occurs in immunocompromised patients or those with chronic diseases. DISTRIBUTIVE SHOCK In about 1/3 of patients, it is caused by gram-positive cocci and Candida Septic, bacteremic shock is based on the organisms. loss of vascular tone. Bacteremia and septic Shock caused by staphylococcal toxins is shock are closely related conditions. called toxic shock, a condition more Bacteremic shock develops when high frequently occurring in young women. levels of bacteremia or fungus and its toxic agents penetrate the bloodstream, Predisposing Factors: 2|E M E R G E N C Y N U R S I N G | LESSON 2 JADE B.BURI  Diabetes mellitus, cirrhosis, leukopenic ✓ oliguria states, especially those related to underlying neoplasms or cytotoxic Late signs treatment. ✓ Cool and pale extremities with Antecedent infections in the urinary, biliary, peripheral cyanosis and mottling. or GI tracts. Invasive devices like catheters, drainage As the condition progresses tubes, and other foreign materials. ✓ multiorgan failure involving the kidneys, Prior treatment with antibiotics, lungs, and liver occurs, along with corticosteroids, or ventilators. disseminated intravascular coagulation SEPTIC SHOCK (DIC) and heart failure. occurs more often in newborns, patients over 35 Laboratory Findings: years of age, pregnant women, and those who Leukocytosis with a marked shift to the left, are severely immunocompromised due to associated with a sharp decrease in underlying diseases or iatrogenic complications platelet count to ≤ 50,000/µL from treatment. respiratory alkalosis Pathogenesis: metabolic acidosis toxic anemia The bacterial toxins generated by infecting positive blood cultures. organisms trigger complex immunologic reactions. Various mediators, including TNF, Management of Distributive Shock leukotrienes, lipoxygenase, histamine, Patients should be treated in an ICU, with bradykinin, serotonin, and IL-2, along with frequent monitoring of: endotoxin (from the lipopolysaccharide component of gram-negative bacilli cell systemic pressure walls), play a role. arterial and venous blood Ph arterial blood gas levels, blood lactate WARM SHOCK levels Initially, vasodilation of arteries and renal function, electrolyte levels arterioles occurs, decreasing peripheral possibly tissue PCO2 arterial resistance with normal or increased Urine output should be measured (usually cardiac output, even though the ejection with an indwelling catheter) as an fraction may decrease when heart rate indication of splanchnic blood flow and increases. visceral perfusion. The CVP or pulmonary artery pressure COLD SHOCK should be measured, and fluid Later, cardiac output may decrease, and replacement should be given until the CVP peripheral resistance may increase. reaches 10-12 cm H2O or until the Despite increased cardiac output, blood pulmonary wedge pressure reaches 12-15 flow to capillary exchange vessels is mmHg. impaired, reducing oxygen delivery and Respiration should be supported with nasal waste removal. O2, tracheal intubation or tracheostomy, This decreased organ perfusion particularly and mechanical ventilation as necessary. affects the kidneys and brain, eventually Parenteral antibiotics should be given after causing failure of one or more visceral specimens of blood, body fluids, and organs. wound sites have been taken for Gram stain Ultimately, cardiac output declines, and and culture. Prompt empiric therapy is the typical features of shock appear. essential. The choice of an antibiotic requires an Clinical Signs: educated guess based on previous culture results from the primary infection site or the ✓ Altered mental alertness clinical setting where the infection ✓ shaking chills occurred. ✓ rapid rise in body temperature ✓ blood pressure decreased to < 80 RARE CASES OF SHOCK mmHg ✓ warm skin (paradoxically warm Shock Due to Hormonal Insufficiency: extremities) ✓ This type of distributive shock occurs ✓ tachycardia due to insufficiency in hormones such as ✓ tachypnea those from the thyroid gland (thyroid) or 3|E M E R G E N C Y N U R S I N G | LESSON 2 JADE B.BURI  pituitary gland (hypophysis), among others. Neurogenic Shock: ✓ This type of distributive shock is characterized by hypotension secondary to central nervous system dysfunction, resulting from the disruption of the sympathetic nervous system. ✓ The main causes include trauma or lumbar anesthesia, which lead to vasomotor dysfunction and paralysis. ✓ This causes vasodilation and decreased vascular resistance, resulting in blood insufficiency in the circulatory system. Shock Due to Hyperergic Reactions: ✓ This type of distributive shock develops as a result of allergic reactions in patients who are hypersensitive to various antigens. 4|E M E R G E N C Y N U R S I N G | LESSON 2 JADE B.BURI  ECG READING & INTERPRETATION - This means that for every second of heart activity being recorded, the Electrocardiography (ECG) is a precise paper moves 25 millimeters horizontally. method used to measure and monitor the 2. Horizontal Measurements: electrical activities of the heart - Large Box: On the ECG paper, one It is captured via external electrodes— large box (which is 5 mm wide) conductive pads attached to the patient’s represents 0.2 seconds (or 200 chest and limbs. milliseconds). The electrical signals are transcribed onto - Small Box: Each small box (which is 1 graph paper, which is marked with a grid of mm wide) within the large box small and large squares. represents 0.04 seconds (or 40 Small square: Represents 40 milliseconds). This helps in accurately milliseconds (ms) along the horizontal measuring the time intervals between axis. different parts of the heart's electrical Large square: Contains 5 small squares, activity. representing 200 ms. 3. Vertical Measurements: The standard paper speeds and square - Vertically, the large box represents 0.5 markings facilitate the measurement of Mv (millivolts). This measurement is cardiac timing intervals, enabling the important for assessing the amplitude calculation of heart rates and the (height) of the electrical signals, which identification of abnormal electrical corresponds to the strength of the conduction within the heart. heart's electrical impulses. Any disturbances in the heart's electrical activity can result in various types of arrhythmias, which may lead to serious consequences, including death. MAJOR COMPONENTS OF THE ELECTRICAL ACTIVITIES OF THE HEART: 4. Grid Layout: - The grid on the ECG paper is designed to allow easy and accurate measurement of both time (horizontally) and voltage (vertically). The image shows a 3-second interval represented by 15 large boxes, each marking 0.2 seconds. The grid and the standard measurements make it easier for healthcare professionals to analyze the ECG tracing, identify heart rates, and detect abnormalities in the heart's electrical conduction. THE ECG PAPER 1. ECG Machine Speed: - The ECG machine operates at a standard speed of 25 mm/second. scale of voltage, measured on the vertical axis, against on time the horizontal axis 1|E M E R G E N C Y N U R S I N G | LESSON 3 JADE B.BURI  THE ECG LEADS ECG leads are the graphical representation of the depolarization of the heart. 6 PRECORDIAL LEADS These leads capture the electrical activity of the heart in a horizontal plane. V1: 4th intercostal space, right parasternal region V2: 4th intercostal space, left parasternal region V3: Midway between V2 and V4 V4: 5th intercostal space, left midclavicular line V5: 5th intercostal space, left anterior axillary line A wave is a deflection of the ECG line V6: 5th intercostal space, left midaxillary line resulting from a change in the electrical activity of the heart. Waves can be categorized based on the direction and characteristics of their deflection: Positive Deflection (Upward): The electrical impulse is moving toward the electrodes. Negative Deflection (Downward): The electrical impulse is moving away from the electrode. Equiphasic (Equally Upward and Downward): The electrical impulse is 1. Limb Leads moving perpendicular to the electrode. I, II, III: These leads capture the Other Waves: Waves can form electrical activity of the heart in a complexes, such as the QRS complex. vertical plane. aVL, aVF, aVR: These are augmented limb leads that also capture the heart's electrical activity in a vertical plane. ANATOMICAL RELATIONSHIP OF LEADS LIMB PRECORDIA CORRESPONDIN LEADS L G HEART THE P WAVE STRUCTURE INFERIOR II N/A Inferior LEADS III surface of The P wave represents atrial depolarization. Avf the heart It occurs when the sinus node, also known LATERAL I V5 Left LEADS aV V6 ventricle, as the sinoatrial (SA) node, creates an L lateral wall action potential that depolarizes the atria. ANTEROSEPTA N/ V1-V4 Anterior L LEADS A wall of Appearance in Lead II: The P wave appears both upright in lead II if the action potential is ventricles Posterior originating from the SA node. wall of the Sequence: Each P wave should be followed left ventricle by a QRS complex ECG COMPONENTS WAVE, SEGMENT, INTERVAL WAVE 2|E M E R G E N C Y N U R S I N G | LESSON 3 JADE B.BURI  THE QRS COMPLEX ✓ There are no specific disease conditions that elevate or depress the T-P segment. The QRS complex, which includes the Q Tachycardia Effects: wave, R wave, and S wave, represents ✓ During tachycardia, the T-P segment is ventricular depolarization. shortened and may become difficult to The normal duration (interval) of the QRS visualize. complex is between 0.08 and 0.10 seconds ✓ It is important to examine the T-P (80 to 100 milliseconds). segment closely for the presence of U When the QRS duration between 0.10 and waves or atrial activity, as these could 0.12 seconds is considered intermediate or indicate pathology. slightly prolonged. A QRS duration greater than 0.12 seconds is QT INTERVAL considered abnormal. Lengthening of QRS Duration: QRS duration The QT interval is the time span from the lengthens when electrical activity takes beginning of the QRS complex longer to travel through the ventricular (representing ventricular depolarization) to myocardium. the end of the T wave (resulting from Normal Conduction System: ventricular repolarization). ✓ The normal conduction system in the Assessing Prolongation: ventricles is called the His-Purkinje ✓ To determine if the QT interval is system, which consists of cells that prolonged, check if the T wave ends conduct electricity rapidly. beyond the halfway point between two ✓ Normal conduction of an electrical R waves (the RR interval). impulse through the atrioventricular ✓ If the T wave ends past this halfway (AV) node and then to the ventricles via point, the QT interval is considered the His-Purkinje system is fast, resulting in prolonged. a normal QRS duration. Widened QRS Duration: ✓ When electrical activity bypasses the His-Purkinje system and instead travels from myocyte to myocyte, more time is needed, leading to a widened QRS duration. S WAVE THE T WAVE The S wave is the first downward deflection The T wave occurs after the QRS complex of the QRS complex that occurs after the R and is the result of ventricular repolarization. wave. However, an S wave may not be Appearance: T waves should be upright in present in all ECG leads for a given patient. most leads, with exceptions in aVR and V1. Normal ECG Appearance: T waves should be asymmetric, with the ✓ In a normal ECG, a large S wave is second portion having a steeper decline typically seen in lead V1, which compared to the incline of the first portion. progressively becomes smaller, with Symmetry and Pathology: If the T wave almost no S wave present in lead V6. appears symmetric, it may indicate cardiac Pathological Changes: pathology, such as ischemia. ✓ A large, slurred S wave is seen in leads I and V6 in the presence of a right bundle branch block. THE T-P SEGMENT The T-P segment is the portion of the ECG that runs from the end of the T wave to the beginning of the P wave. Baseline Reference: ✓ This segment should always be at S-T SEGMENT baseline and is used as a reference to The S-T segment represents the interval determine whether the ST segment is between ventricular depolarization and elevated or depressed. repolarization. 3|E M E R G E N C Y N U R S I N G | LESSON 3 JADE B.BURI  Appearance: It typically appears as a ✓ Idiopathic Ventricular Fibrillation horizontal isoelectric line but may slope ✓ Hypercalcemia upward slightly before the onset of the T ✓ Hypothermia wave. Extent: The S-T segment extends from the J point (the end of the QRS complex) to the start of the T wave. ETIOLOGY Normal Findings: Small, concave elevation U WAVE seen in young, healthy adults, often due to early repolarization. The U wave is a small deflection that occurs STEMI (ST-Elevation Myocardial Infarction): after the T wave. Significant S-T elevation associated with The polarity of the U wave is the same as myocardial infarction (MI). that of the T wave. LBBB (Left Bundle Branch Block): S-T Best seen in leads V2 to V4, but it is not elevation can be seen in the presence of a always visible. left bundle branch block. A normal finding in athletes. Pericarditis: Widespread S-T elevations throughout the ECG. ETIOLOGY Pulmonary Embolism: S-T elevation may The exact cause of the U wave is unknown, occur as a result of a pulmonary embolism but it is thought to be due to delayed Brugada Pattern: A specific ECG pattern repolarization of myocardial cells or the His- that includes S-T elevation, often associated Purkinje system. with a risk of sudden cardiac death. Most prominent in patients with: Left Ventricular Aneurysm: Persistent S-T ✓ Hypokalemia elevation may indicate a left ventricular ✓ Hypercalcemia aneurysm. ✓ Bradycardia COUNTING THE HEART RATE Heart Rate The standard ECG paper speed is 25 mm/sec, equivalent to 5 large squares per second. S-T DEPRESSION ETIOLOGY If the interval between two beats (R-R interval) is 5 large squares, the heart rate Down sloping ST depression Subendocardial or horizontal ST depression myocardial ischemia (HR) is 60 beats per minute. Stress-induced The HR can be quickly estimated by dividing myocardial Ischemia Reciprocal change from 300 by the number of large squares myocardial Infarction between two heartbeats (R-R interval). Upsloping of s-t depression Normal during ✓ 1 large square → HR = 300 beats/min tachycardia May indicate ✓ 2 large squares → HR = 150 beats/min myocardial ischemia if ✓ 3 large squares → HR = 100 beats/min the clinical feature suggests acute coronary ✓ 4 large squares → HR = 75 beats/min syndrome ✓ 5 large squares → HR = 60 beats/min Sagging of s-t segment Digoxin depression ✓ 6 large squares → HR = 50 beats/min Secondary repolarization Ventricular hypertrophy abnormalities LBBB Non-specific s-t segment Hypokalemia depression J WAVE The R-R interval in this illustration is between 2-3 squares so then the HR is between 150-100 or The J wave is a positive deflection that +/- 120 occurs between the QRS complex and the S-T segment. Irregular Heart Rhythm It marks the point where depolarization ends and repolarization begins. When a patient’s heart rhythm is irregular, Conditions Associated with J Waves: the standard method of heart rate ✓ Brugada Syndrome calculation (using the R-R interval) is 4|E M E R G E N C Y N U R S I N G | LESSON 3 JADE B.BURI  ineffective because the R-R interval varies Uniform P Waves: All P waves should be significantly throughout the ECG. uniform in shape. Alternative Calculation Method: Normal P Wave Axis: ✓ Count the Number of Complexes: ✓ The P wave axis should be in the left Count the total number of QRS lower quadrant (0-90 degrees). complexes on the rhythm strip. ✓ This typically means the P wave is ✓ Calculate Heart Rate: upright in both lead I and lead aVF, - For an irregular QRS rhythm, use the except in cases of dextrocardia. formula: R-R INTERVAL AND SINUS ARRHYTHMIA: HR = 6 × Total Number of QRS Complexes The R-R interval in NSR does not have to be identical and may vary with breathing, a - This gives the average heart rate in phenomenon known as sinus arrhythmia. beats per minute by estimating the Sinus arrhythmia is more noticeable at number of complexes over 1 slower heart rates. minute. 1. Heart rate increases during inspiration ✓ Example: due to: - 10 complexes on a rhythm strip - Increased venous return - 10 x 6 = 60 beats per minute - Increased sympathetic tone 2. Heart rate increases during expiration DETERMINE THE HEART RYTHM due to: HEART RHYTHM - Decreased venous return - Increased parasympathetic tone ATRIAL RHYTHM Characterized by narrow QRS complexes are preceded by P waves that do not meet one or more of the normal sinus rhythm Irregularly Irregular (NSR) criteria. If P wave morphology changes, it may (Atrial Fibrillation) suggest a multifocal origin, a condition Cardiac muscle cells (myocytes) possess known as a "wandering pacemaker." inherent automaticity, meaning they can AV NODAL OR JUNCTIONAL RHYTHM generate an electrical impulse on their own. Characterized by narrow QRS complexes The sinoatrial (SA) nodal cells have the that are not preceded by P waves. fastest automaticity, acting as the heart's An inverted P wave may appear after the natural pacemaker, and therefore control QRS complex due to retrograde the heart rate and rhythm. conduction. There are four levels of conduction and potential pacemakers in the heart, VENTRICULAR RHYTHM arranged from fastest to slowest: Characterized by wide QRS complexes that ✓ SA Node rhythm are not preceded by P waves. ✓ Atria rhythm ✓ AV Node or junctional rhythm HIERARCHY OF PACEMAKER CONTROL ✓ Ventricles rhythm If the heart rhythm is not sinus (originating If the sinus node fails to initiate the impulse, from the SA node), it is important to an atrial focus will take over as the determine the origin of the pacemaker and pacemaker, usually resulting in a slower identify where the impulse is initiated. heart rate than NSR. If the atrial focus fails, the AV node assumes SA NODAL RHYTHM (NORMAL SINUS RHYTHM) control as the pacemaker. If the AV node fails, the ventricular focus, The sinus node is located at the junction of the slowest of all, will take over as the the superior vena cava (SVC) and the right pacemaker. atrium. Each time the pacemaker focus is CRITERIA FOR SINUS RHYTHM: downgraded (from sinus node to atrial, AV node, or ventricular focus), the heart rate P Wave Before Each QRS Complex: There becomes slower due to the inherent must be one P wave preceding each QRS automaticity of the pacemaker cells at complex. each level. 5|E M E R G E N C Y N U R S I N G | LESSON 3 JADE B.BURI  HEART BLOCKS In adults, the normal cardiac axis ranges between -30° and +90° (from FIRST-DEGREE HEART BLOCK approximately 11:00 o'clock to 5:00 o'clock Sinus rhythm with first-degree heart block is on a clock face). characterized by a sinus rhythm with a prolonged PR interval greater than 0.20 If electrical activity is travelling towards seconds. an ECG lead, there will be a positive deflection The prolonged PR interval is due to a delay If the electrical activity is travelling away in the transmission of electrical impulses from an ECG lead, there will be a from the atria to the ventricles negative deflection Determining the Cardiac Axis: The cardiac axis can be determined by analyzing leads I, II, and III on the ECG. SECOND-DEGREE AV BLOCK ✓ The overall direction of electrical Mobitz Type I (Wenckebach): Progressive activity is toward these leads (I, II, III) lengthening of the PR interval until a QRS ✓ This results in a positive deflection in all complex is eventually dropped. three leads, with lead II typically Mobitz Type II: Intermittent dropping of QRS showing the most positive deflection complexes without the progressive PR since it is most closely aligned with the interval lengthening seen in Mobitz Type I. overall direction of electrical spread Mobitz Type II must be carefully evaluated, ✓ The lead aVR typically shows the most as it can rapidly progress to a complete negative deflection because it views heart block. the heart in the opposite direction of the normal electrical activity. THIRD-DEGREE HEART BLOCK (COMPLETE HEART BLOCK) Third-degree heart block, also known as complete heart block, is a rhythm in which there is no relationship between the P METHODS OF DETERMINING CARDIAC AXIS waves and the QRS complexes. Characteristics: 1. Isoelectric (Equiphasic) QRS Method ✓ The P to P intervals are regular. Identify the lead in which the QRS ✓ However, the P waves have no complex is isoelectric (equal positive consistent relationship with the QRS and negative deflections). complexes on the ECG. Determine the two leads that are perpendicular to the identified isoelectric lead on the Cabrera circle. The cardiac axis corresponds to the lead that is perpendicular to the isoelectric lead. This method is generally more accurate than the Lead I and aVF method. CARDIAC AXIS 2. Lead I and aVF Method Determine the polarity of the QRS The cardiac axis represents the overall complex in leads I and aVF. direction of electrical spread within the ✓ Positive QRS Complex: The area heart above the isoelectric line and under The cardiac axis represents the mean the curve is larger than the area direction of ventricular depolarization in the below the isoelectric line. frontal plane. 6|E M E R G E N C Y N U R S I N G | LESSON 3 JADE B.BURI  ✓ Negative QRS Complex: The area Antithrombotic therapy is recommended below the isoelectric line and for all patients with AF except those with above the curve is larger than the lone AF or contraindications (Level A). area above the isoelectric line. Chronic oral anticoagulant therapy with a Approximate the cardiac axis by vitamin K antagonist is recommended in a evaluating the combinations of QRS dose to achieve the target INR of 2.0 to 3.0 complex polarities in leads I and aVF: unless contraindicated (Level A). This is for ✓ Positive in both leads I and aVF: patients without mechanical heart valves Normal axis. at high risk of stroke (prior stroke, TIA, or ✓ Positive in lead I and negative in systemic embolism; rheumatic mitral aVF: Left axis deviation. stenosis), ✓ Negative in lead I and positive in Anticoagulation with a vitamin K antagonist aVF: Right axis deviation. is recommended for patients with more ✓ Negative in both leads I and aVF: than one moderate risk factor (age >75, Extreme right axis deviation. hypertension, HF, LVEF