Chapter 41: Oxygenation

Ventilation

Movement of air into and out of the lungs, during inspiration the diaphragm and external intercostals contract to create negative pressure

Perfusion

Movement of blood through pulmonary capillaries

Diffusion

Passive gas movement across alveolocapillary membrane along a concentration gradient

Work of Breathing

Effort required to expand and contract the lungs, determined by surfactant, compliance, and airway resistance

Surfactant

Chemical produced in alveoli that lowers surface tension and prevents collapse

Tidal Volume

Amount of air exhaled after normal inspiration

Residual Volume

Air remaining in alveoli after forced maximal expiration

Forced Vital Capacity

Maximum volume removed during forced expiration

Oxyhemoglobin

Hemoglobin bound to oxygen, makes up 97% of O2 in the body

Cardiac Output

Stroke volume x heart rate, should be 4 to 8 L/min

Frank Starling Law

Greater myocardial stretch during diastolic filling leads to stronger subsequent contraction and larger stroke volume

Preload

Amount of blood in left ventricle at end of diastole before next contraction

Afterload

Resistance to the ejection of blood from the left ventricle

Myocardial Contractability

Ability of heart to squeeze blood from the ventricles

Electrocardiogram

Measurement of electrical activity of the conduction system

P Wave

Atrial depolarization, represents electrical conduction through atria

PR Interval

Impulse travel time from SA node to purkinje fibers, usually 0.12 to 2 sec

QRS Complex

Ventricular depolarization, electrical impulses travel through ventricles

QT Interval

Time needed for ventricular depolarization and repolarization, should be 0.12 to 0.42 sec

Hypoventilation

Inadequate alveolar ventilation from shallow or too little respirations leading to CO2 retention and respiratory acidosis

Hyperventilation

Excessive CO2 elimination from rapid or deep breathing causing hypocapnia and respiratory alkalosis, triggered by anxiety, fever, aspirin, poisoning, or metabolic acidosis compensation

Hypoxia

Cellular oxygen deficiency caused by decreased hemoglobin, diminished O2, inability of tissues to extract O2 from blood, decreased O2 diffusion, poor tissue perfusion, or impaired ventilation

Early Hypoxia

Apprehension, restlessness, inability to concentrate, agitation, tachycardia, elevated BP, and tachypnea

Late Hypoxia

Cyanosis and bradypnea

Conduction Disturbances

Electrical impulses originating from outside of SA node, classified by cardiac response and site of impulse origin

Atrial Fibrillation

Electrical impulse in atria is chaotic and originates from multiple sites causing atria to beat irregularly and out of sync with ventricles

Paroxysmal Supraventricular Tachycardia

Sudden, rapid onset of tachycardia originating above AV node

Left Sided Heart Failure

Decreased functioning in left ventricle leading to decreased CO, causes fatigue, breathlessness, dizziness, confusion, and eventually pulmonary congestion

Right Sided Heart Failure

Decreased functioning in right ventricle, usually due to pulmonary disease or chronic left sided HF, causes weight gain, distended neck veins, hepatomegaly, splenomegaly, and dependent peripheral edema

Myocardial Ischemia

Supply of blood to myocardium from coronary arteries is insufficient to meet demands

Angina Pectoris

Transient imbalance between myocardial O2 supply and demands, causes chest pain that is aching, sharp, tingling, burning, or feels like pressure, usually left sided or substernally and radiates to arms, jaw, neck, and back, lasts 3 to 5 minutes

Myocardial Infarction

Sudden decrease in coronary blood flow or increase in oxygen demand, occurs when ischemia is not reversed, cells will die after 20 min

DASH Diet

Eating plan used to treat/prevent hypertension, encouraged potassium, calcium, magnesium, protein, and fiber and discourages excessive sodium, saturated/trans fats, and sugar

Wheeze

Continuous, high pitched musical sound caused by air movement through a narrowed airway, associated with asthma, bronchitis, or pneumonia

Crackles

Discontinuous popping sounds usually during inspiration caused by alveoli opening or air moving through fluid filled passageways, cannot be cleared by coughing, associated with pneumonia, emphysema, or chronic bronchitis

Rhonchi

Low pitched rattling sounds during expiration caused by thick secretions or muscle spasms, can be cleared by coughing, associated with asthma and pneumonia

Complete Blood Count

Test that determines number and type of RBCs and WBCs per cubic millimeter of blood

Creatine Kinase

Cardiac enzyme released from cells when myocardial tissue is damaged, levels increased within 4-6 hours of MI

Plasma Cardiac Troponin 1

Cardiac troponin that elevates about 3 hours after myocardial injury

Plasma Cardiac Troponin T

Cardiac troponin that remains elevated 10 to 14 days after MI

Potassium

Serum electrolyte, lowers with diuretic therapy and raises with ACE inhibitors, has effect on cardiac rhythm

Low Density Lipoprotein

Bad cholesterol caused by excessive intake of saturated fatty acids, dietary cholesterol, and obesity

High Density Cholesterol

Good cholesterol

Holter Monitor

Portable ECG worn outside of hospital, tracks electrical activity of heart during ADLs

Stress Test

ECG performed while patient walks on treadmill

Electrophysiological Study

Invasive measure of intracardiac electrical pathways, provides more specific info about difficult to treat dysrhythmias

Scintigraphy

Radionuclide angiography, evaluates cardiac structure, myocardial perfusion, and contractibility

Thoracentesis

Surgical perforation of chest wall and pleural spaces with a needle to aspirate fluids or remove specimen

Huff Cough

Deep breath, hold 2-3 sec, and forcefully exhale saying “huff”, helps move secretions to larger airways

Cascade Cough

Deep breath, hold 1 to 2 sec, and then series of coughs through exhalation, used for patients with larger amounts of sputum

Quad Cough

Manually assisted inward/upward abdominal thrust during exhalation for spinal cord injury patients

Positive Expiratory Pressure

Allows air to be inhaled normally but forces patient to exhale against resistance, helps air get behind mucus

Oropharyngeal Airway

Plastic piece that prevents obstruction of trachea by displacement of tongue into oropharynx, only used in unconscious patients

Nasopharyngeal Airway

Hollow tube is inserted into nose until it reaches posterior pharynx, can be used on conscious patients

Endotracheal Tube

Short term, artificial airway used to administer invasive mechanical ventilation, relieve upper airway obstruction, protect against aspiration, and clear secretions, tube is inserted through mouth into trachea

Tracheostomy Tube

Artificial airway inserted surgically/percutaneously directly into trachea, used for prolonged ventilation, upper airway obstruction from trauma, or difficulties with airway clearance

Pharyngeal Suctioning

Performed when a patient can cough but is unable to clear secretions, apply suctioning after a patient has coughed

Tracheal Suctioning

Performed when a patient with pulmonary secretions is unable to manage secretions by coughing

Invasive Mechanical Ventilation

Life support treatment that delivers positive air pressure directly into the lungs through an artificial airway, used to support gas exchange, increase lung volume, and reduce WOB

Noninvasive Positive Pressure Ventilation

Maintains positive pressure airway and improves alveolar ventilation without an artificial airway, includes CPAP and BiPAP

Chest Tube

Catheter inserted through ribcage into pleural space to remove air/fluids/blood, prevent reentering, or reestablish normal intrapleural/intrapulmonic pressures

Capnography

Continuous, real time measurement of end tidal CO2 near end of exhalation to evaluate ventilation, perfusion, and metabolic status

Chest Physiotherapy

External chest wall manipulation utilizing postural drainage, manual percussion, vibration, or high frequency chest wall compression to mobilize secretions

Cheyne Stokes Respirations

Abnormal respiratory pattern characterized by alternating periods of apnea and breathing, caused by brainstem injury or decreased cerebral blood flow

Hemothorax

Accumulation of blood and fluid in pleural spaces, usually caused by trauma or ruptured blood vessels

Hypovolemia

Abnormally low circulating blood volume resulting from extracellular fluid loss, hemorrhage, or dehydration

Incentive Spirometer

Visual feedback device promoting sustained maximum inspiration to prevent/treat atelectasis

Kussmaul Respirations

Abnormally deep, rapid breathing (>35), triggered by metabolic acidosis to blow off CO2

Nebulization

Aerosolization process suspending liquid droplets in inspired air to humidify airways and administer meds

Minute Volume

Respiratory rate x tidal volume, amount of air moving in and out of the body in one minute

PaO2

Amount of oxygen free floating in the blood, should be 80-100

SpO2

Amount of oxygen attached to hemoglobin, should be >95%

Arterial Blood Gases

Blood test that determines the blood pH, PaCO2, HCO3-, and PaO2

Nasal Cannula

Low flow oxygen device, delivers 1-6 L/min, FiO2 of 24-44%, used for modest need of oxygen, each liter increases FiO2 by 4%

Simple Mask

Low flow oxygen device, delivers 5-10 L/min, FiO2 of 35-60%, used for moderate need of oxygen

Partial Rebreather

Low flow oxygen device, delivers 6-15 L/min, FiO2 of 35-60%, has variable delivery

Non-Rebreather Mask

High flow oxygen device, delivers 10-15 L/min, bag must stay inflated, requires spontaneous breathing

Venturi Mask

High flow oxygen device, delivers 2-15 L/min, FiO2 of 24-50%, most controlled FiO2

High Flow Nasal Cannula

High flow oxygen delivery device, delivers up to 60 L/min, FiO2 of 60-90%