Oxygenation and Tissue Perfusion: Comprehensive Exam Notes
Oxygenation and Tissue Perfusion
Overview of Cardiac Function
Cardiac Output (): The amount of blood pumped by the ventricles in one minute. It is a critical measure of heart function.
Normal adult range: L/min.
Formula: (Cardiac Output = Stroke Volume \times Heart Rate).
Stroke Volume (): The amount of blood the heart pumps each time it beats.
Normal adult range: ml/beat.
Heart Rate (): The number of times the heart beats per minute.
Components of the Cardiopulmonary System
Cardiovascular System: Primarily responsible for pumping blood to deliver oxygen (O${2}$) and nutrients throughout the body and remove carbon dioxide (CO${2}$) and waste products.
Pulmonary System: Facilitates gas exchange, bringing O${2}$ into the body and expelling CO${2}$.
Control: Neural and chemical signals regulate the rate and depth of breathing.
Anatomy of the Heart
Protective Chambers: The heart is enclosed by the pericardium, which consists of several layers.
Epicardium: The outer layer, also known as serous pericardium, protects the heart and secretes serous fluid.
Myocardium: The second and thickest layer, composed of contractile muscle that is responsible for pumping blood out of the heart.
Endocardium: The innermost layer, a smooth lining that covers the heart chambers, valves, and vessels.
Blood Flow through the Heart:
Right side receives deoxygenated blood from the body and pumps it to the lungs.
Left side receives oxygenated blood from the lungs and pumps it to the body.
Key components involved in blood flow:
Superior Vena Cava (SVC) and Inferior Vena Cava (IVC): Bring deoxygenated blood to the right atrium.
Right Atrium: Receives deoxygenated blood.
Tricuspid Valve: Controls blood flow from the right atrium to the right ventricle.
Right Ventricle: Pumps deoxygenated blood into the pulmonary artery.
Pulmonary Artery: Carries deoxygenated blood to the lungs.
Pulmonary Veins: Bring oxygenated blood from the lungs to the left atrium.
Left Atrium: Receives oxygenated blood.
Mitral (Bicuspid) Valve: Controls blood flow from the left atrium to the left ventricle.
Left Ventricle: Pumps oxygenated blood into the aorta.
Aorta: Distributes oxygenated blood to the systemic circulation.
Cardiac Cycle Pressures:
Preload: The amount of blood and pressure in the ventricle at the end of diastole (filling phase). This reflects the stretch of the myocardial fibers before contraction.
Afterload: The resistance the ventricle must overcome to eject blood during systole (ejection phase).
Cardiovascular Risk Factors
Non-Modifiable Risk Factors:
Heredity (genetics)
Age
Gender
Modifiable Risk Factors:
Elevated serum lipid levels (dyslipidemia)
Hypertension (HTN)
Cigarette smoking (including second-hand smoke)
Diabetes mellitus
Obesity
Sedentary lifestyle
Altered Structure and Function of Oxygenation: Cardiovascular (Heart Issues)
Nursing Priority: Assess and maintain airway, promote O$_{2}$ delivery, and identify risk factors early.
Oxygenation Problems: Can arise from heart (pump issues) or lungs (ventilation/gas exchange issues).
Heart Issue: Poor O$_{2}$ delivery to tissues.
Lung Issue: Poor O${2}$ entry or CO${2}$ removal.
Cardiovascular Alterations:
Interrupted Electrical Impulses: The Sinoatrial (SA) node is the heart's natural pacemaker, normally setting a rhythm of beats per minute (bpm).
Abnormal rhythms (arrhythmias) lead to decreased O$_{2}$ delivery.
Decreased Blood Flow: Often caused by damage to vascular structures.
Coronary Arteries: These arteries (Right Main, Left Main, Circumflex, Left Anterior Descending, Posterior Descending, Right Marginal branches) supply blood to the heart muscle (myocardium).
Blockage leads to decreased perfusion of the heart muscle.
Cardiac Failure: Impaired contractility of the heart muscle.
Causes: Valve disease, hypertension, vascular damage, B-vitamin deficiency, fluid overload.
Impairs systolic function (ejection fraction) and the heart's ability to meet the body's tissue needs (cardiac output).
Can lead to ventricular dilation.
Assessment Findings (Cardiac):
Electrolyte disturbances
Irregular heartbeat
Difficulty breathing
Dizziness, possible syncope
Decreased Level of Consciousness (LOC)
Vascular Conditions
Atherosclerosis: Formation of atheromas (plaques of lipid material) within the inner and central walls of arteries, leading to thickening and hardening.
Arteriosclerosis: General term for hardening of the arteries.
Risk Factors: Same as CVD risk factors.
Priority Symptoms to Report to PCP:
Shortness of Breath (SOB), especially when supine (orthopnea).
Weight gain of lbs/day or lbs/week, which can indicate fluid retention in heart failure.
Cough producing pink-tinged sputum (pulmonary edema).
New swelling (edema) in feet, ankles, or abdomen.
Coronary Artery Disease (CAD) and Myocardial Infarction (MI)
Coronary Artery Disease (CAD): Narrowed or blocked coronary arteries.
Can lead to angina (chest pain due to reduced blood flow).
Increases risk for Myocardial Infarction (MI).
Myocardial Infarction (MI): A "heart attack" caused by total blockage of a coronary artery, often due to blood clot formation or plaque buildup.
Etiology: Total blockage of a coronary artery resulting in myocardial necrosis.
Signs/Symptoms: Chest pain radiating (neck to navel area), dyspnea, diaphoresis (sweating), nausea/vomiting.
Interventions (MI Priority): Treat chest pain, administer O$_{2}$, call PCP STAT.
Respiratory System: Mechanics and Patterns
Inspiration (Inhalation): Movement of air into the lungs.
Brain signals via phrenic and intercostal nerves cause the diaphragm to contract and move down, and the chest cavity expands.
Intra-alveolar pressure drops, causing air to rush in.
Expiration (Exhalation): Movement of air out of the lungs.
Diaphragm relaxes, and lungs recoil.
Intra-alveolar pressure rises, pushing air out.
Terms to Know - Respiratory Patterns (Normal range: bpm)
Eupnea: Quiet, regular breathing at a normal rate (e.g., bpm). Normal pattern.
Tachypnea: Rapid and shallow breathing ( bpm).
Causes: Fever, exercise, anxiety, respiratory disorders (pneumonia, pain).
Bradypnea: Abnormally slow breathing ( bpm).
Causes: Increased intracranial pressure (ICP), brain damage, narcotics, sedatives.
Hyperventilation: Rapid, deep breaths, leading to overexpansion of the lungs.
Causes: Extreme exercise, fear, anxiety, Diabetic Ketoacidosis (DKA), aspirin overdose. Causes respiratory alkalosis (decreased CO${2}$). Body attempts to blow off CO${2}$ to correct metabolic acidosis (as in DKA).
Hypoventilation: Slow, shallow breaths, leading to less alveolar ventilation and increased CO$_{2}$ (respiratory acidosis).
Causes: Pneumonia, pain.
Cheyne-Stokes Respirations: Cycles of progressively deeper, then shallower breaths, followed by periods of apnea (typically seconds or more in adults, which is an emergency).
Causes: Heart failure, renal failure, increased ICP, impending death, drug overdose. Common in end-of-life patients (expected finding).
Do not confuse with Biot breathing.
Kussmaul Breathing: Abnormally deep, rapid, regular breaths.
Causes: DKA (body attempts to blow off CO$_{2}$ to correct metabolic acidosis).
Intervention: Give insulin for DKA.
Apnea: No breathing for several seconds. If > seconds in adults, it's an emergency.
Causes: Respiratory distress, obstructive sleep apnea, cardiac arrest.
Intervention: Immediate emergency, airway support.
Biot Breathing: Clusters of shallow breaths ($2-3$) followed by irregular apnea.
Similar to Cheyne-Stokes but irregular (not rhythmic).
Causes: Meningitis, severe brain injury.
Respiratory Tract Anatomy
Upper Respiratory Tract: Nose, nasal cavity, sinuses, pharynx.
Function: Warm, moisten, and filter inhaled air.
Lower Respiratory Tract: Larynx (vocal cords), trachea, bronchi, bronchioles, alveoli.
Alveoli: Tiny air sacs where O${2}$ enters the blood, and CO${2}$ leaves.
Nursing Interventions for Respiratory Patterns
Kussmaul breathing (DKA): Give insulin.
Cheyne-Stokes in dying patient: Expected finding.
Bradypnea + pinpoint pupils: Suspect opioid overdose; administer naloxone.
Tachypnea + anxiety: First assess SpO$_{2}$, then calm the patient.
Apnea: Immediate emergency, provide airway support.
Altered Structure and Function of Oxygenation: Respiratory Alterations
Chronic Obstructive Pulmonary Disease (COPD): An umbrella term for impaired airflow in the lungs, encompassing emphysema and chronic bronchitis.
Causes: Airway spasms, bronchial narrowing, inflammation.
Emphysema: Destruction of alveolar walls and enlargement of gas exchange airways.
Decreased elasticity.
Results in air trapping, making expiration difficult (hypercapnia, increased CO$_{2}$). Also leads to hyperinflation, potentially causing a "barrel chest."
Causes: Smoking (#1), family history, pollutants, childhood infections, age.
Chronic Bronchitis: Inflammation of larger airways, characterized by increased mucus production and airway damage (ciliary damage).
Leads to chronic cough, difficulty removing mucus.
Patients are sometimes called "blue bloaters" due to cyanosis and edema, in addition to mucus and infection.
Causes: Smoking (including second-hand smoking), pollutants, recurrent infections.
COPD Nursing Priority: Risk of CO${2}$ retention. Monitor O${2}$; avoid giving high-flow O${2}$ unless specifically ordered (often target SpO${2}$ %).
Asthma: Chronic inflammatory airway disease.
Causes: Allergies, inflammation, constriction of airways, mucus accumulation, airway obstruction.
Triggers: Allergens, pollutants, exercise, cold air.
Symptoms: Dyspnea, wheezing (especially on expiration), chest tightness, prolonged expiration (feeling like squeezing air through a straw).
Treatment: Bronchodilators (for emergency relief) and long-term steroids (for inflammation).
Asthma Attack Priority: Wheezing + dyspnea + prolonged expiration = Administer bronchodilators.
Pneumonia: Infection of the alveoli (bacterial, viral, fungal).
Symptoms: Fever, cough, increased secretions, dyspnea.
Priority Care: Monitor gas exchange, airway clearance, aspiration precautions.
Aspiration Precautions: Thickened liquids, position patient upright for feeding/drinking.
Pneumonia Priority: Monitor oxygenation and aspiration risk.
Atelectasis: Blockage or collapse of alveoli, resulting in hypoventilation.
Causes: Shallow breathing, retained secretions, post-operative pain (especially after abdominal/chest surgery leading to shallow breathing).
Symptoms: Dyspnea, decreased breath sounds, hypoxemia.
Risk: Post-operative patients prone to shallow breathing due to incision pain.
Post-op Atelectasis Priority: Encourage incentive spirometry, deep breathing, and ambulation.
Respiratory Failure: Lungs cannot maintain adequate O${2}$/CO${2}$ exchange.
Causes: COPD, untreated pneumonia, COVID-19.
COVID-19: A viral respiratory illness caused by SARS-CoV-2.
Symptoms: Fever, cough, SOB, fatigue, loss of taste/smell, GI upset.
Symptoms appear: days after exposure.
Risk Factors: Elderly, stroke, diabetes, chronic lung or kidney disease.
Prevention: Vaccination, hand hygiene, social distancing (at least ft), masks.
Hypoxemia and Hypoxia
Hypoxemia: Low levels of oxygen in the blood.
Hypoxia: Insufficient oxygen anywhere in the body.
Signs/Symptoms (Check O$_{2}$ saturation):
Increased pulse
Shallow respirations
Dyspnea
Increased restlessness
Cyanosis (bluish discoloration)
Nasal flaring
Retractions (use of accessory muscles for breathing)
General Nursing Priorities and Warning Signs
Airway always comes first (A in ABCs).
MI Warning Signs: Chest pain, diaphoresis, dyspnea, weak/absent pulses, new edema \Rightarrow Always a priority (ABC + Circulation).
Heart Failure (HF) Warning Signs: Sudden weight gain (e.g., lbs/day or lbs/week), pink frothy sputum (pulmonary edema) \Rightarrow Call PCP STAT.
COPD Signs: Barrel chest and use of accessory muscles \Rightarrow Airway is priority.
Edema + weight gain: Suggests HF \Rightarrow Call PCP.
Assessment: Gathering Data
Chief Complaints: Shortness of breath (SOB), chest pain, fatigue.
Subjective Data (Health History):
Cough
Smoking history: Current/past (packs per day, duration).
History of cardiac/pulmonary diseases: Asthma, COPD, HF, pneumonia, etc.
Associated symptoms: Dizziness, syncope, orthopnea (sleeping on pillows for comfort).
Lifestyle: Exercise habits, occupation (exposure to pollutants), immunizations (flu, pneumonia).
Objective Data (Physical Assessment and Vitals):
Vital Signs: Blood pressure (lying, sitting, standing to check for orthostatic hypotension), respiratory rate, apical and peripheral pulses.
Pulse Deficit: If apical pulse rate is greater than the peripheral pulse rate, indicates ineffective cardiac contractions or arrhythmias.
O$_{2}$ Saturation (Pulse Oximetry): Measures oxygen saturation levels.
Cough Assessment: Onset, duration (acute vs. chronic), associated signs (fever, wheezing, chest tightness).
Hemoptysis: Spitting up blood (flaky, streaks, or frank blood). A red flag that may indicate Tuberculosis (TB), cancer, or Pulmonary Embolism (PE). Document carefully.
Sputum Characteristics: Color, consistency, amount.
Peripheral Vascular Assessment: Edema, pulses, skin color and texture, capillary refill.
Edema: Caused by vascular pressure, poor venous return, lymphatic blockage. Location typically ankles, feet, hands.
Pulses: Assess for strength (thready/absent pulses indicate poor perfusion), symmetry.
Skin: Pallor, cyanosis, shiny/thin skin.
Capillary Refill: seconds indicates impaired perfusion.
Cardiac Assessment
Inspection:
Precordium: Observe chest wall movement related to heartbeat. Abnormal: Left ventricular hypertrophy.
Barrel-shaped chest: Indicates air trapping (common in COPD).
Use of accessory muscles: Sign of respiratory distress.
Palpation:
Check for thrills: Vibrations from turbulent blood flow, indicating hyperactivity or valve disease.
Auscultation:
Normal Sounds: S1 (