Chapter 39, Oxygenation

Taylor's Fundamental s of Nursing Care
Chapter 39, Oxygenation

These notes may be sparse. I am a respiratory therapist and may not focus much on this chapter.

Anatomy and Physiology of Respiration

Three functions:

• ventilation
• respiration
• perfusion

Normal function depends on:

• integrity of airway to transport air to and from lungs
• ability of alveoli to participate in gas exchange
• properly functioning cardiovascular and hematologic system to wastes and nutrients to and from tissues

Structures of Respiratory System:

• begins at nose and ends at terminal bronchioles
• divided into upper and lower airways

• Upper Airway:
• composed of nose, pharynx, larynx, and epiglottis
• function is to warm, filter, and humidify air
• Lower Airway:
• tracheobronchial tree
• includes trachea, R and L mainstream bronchi, segmental bronchi, and terminal bronchioles
• functions are conduction of air, mucocilliary clearance, and production of surfactant

• Airways are lined with mucous to traps cells, particles, and infectious debris
• Cilia propel trapped material toward the upper airway to be removed by coughing or swallowing
• adequate fluid intake in needed for mucous to maintain watery consistency to move particles
• Lungs are the main organs of respiration
• Each lung is divided into lobes
• right has 3 lobes, left has 2
• At the end of the terminal bronchioles are clusters of alveoli
• they are the site of gas exchange
• walls are made of single layer of simple squamous epithelium
• allow for gas exchange with capillaries covering alveoli
• adult has > 300 million alveoli
• surfactant reduces surface tension between moist membranes of alveoli, preventing collapse 

• Lungs and thoracic cavity lined with serous membrane called pleura
• visceral pleura covers lungs, parietal pleura lines thoracic cavity
• two membranes are continuous with each other and form fluid filled sac
• pleural space lies between the two layers
• pleural fluid acts as adhesive and lubricant
• aids with ease of filling and emptying of lungs

• Pressure within pleural space (intrapleural space) is always sub atmospheric and keeps the lungs in an expanded position

Physiology of Respiratory System:

Cells require oxygen and removal of carbon dioxide with is a byproduct of oxidation. Pulmonary ventilation is movement of air into and out of the lungs. Respiration is the exchange of air. Perfusion is delivery to tissues.

Pulmonary Ventilation:

• Movement of air into and out of lungs
• 2 phases, inhalation and exhalation
• Inspiration- active phase, involves movement of muscles
• Expiration- passive phase, movement of air out of lungs
• Immediately before inspiration, air pressure in lungs is equal to that of surrounding atmospheric pressure
• The pressure in the lungs decreases as the volume increases
• Other factors that contribute to air flow into and out of lungs:
• musculature
• compliance of lung tissue
• airway resistence
• Lung compliance is ease with which lungs can be inflated and affects lung volumes
• ability of lungs to fill is aided by elasticity and surfactant
• emphysema results in decreased elasticity and compliance
• Airway resistance is any obstruction or impediment of air as it moves through the airway
• bronchial constriction in asthma is a form of airway resistance sue to decreased diameter of airways

Respiration:

• gas exchange occurs at terminal alveolar capillary system
• via diffusion - high concentration to lower concentration 
• the greater pressure of O2 in the alveoli forces the O2 to diffuse into the unoxygenated venous blood; CO2 from blood to alveoli
• Diffusion of gases in the lung is influenced by four factors:
• change in surface area available
• thickening of alveolar capillary membrane
• partial pressure
• solubility and molecular weigh of gas

• Surface Area:
• any detrimental change in area available for gas exchange hinders diffusion
• removal of lug or disease that damages tissue decreases surface area
• atelectasis decreases surface area
• conditions that can lead to atelectasis: obstruction d/t foreign body, mucous plugging, airway constriction, external compression (tumors or large blood vessels), and immobility
• any disease that results in thickening or alveolar membrane affects diffusion

• Partial Pressure
• pressure resulting from any gas in a mixture depending on its concentration
• higher altitudes have lower partial pressure of oxygen

• Solubility and Molecular Weight
• CO2 has greater solubility and diffuses more quickly allowing it to be exhaled during each expiratory phase

Perfusion:

• Perfusion- oxygenated capillary blood passes through the tissues of the body
• the amount of blood flowing through the lungs is a factor in the amount of oxygen and other gases exchanged
• can depend on pts position and activity level
• increased activity results in increased needed for cellular oxygen in body's tissue which leads to an increase in cardiac output and increase of blood to lungs
• perfusion also depends on adequate cardiovascular functioning

• Hypoxia- condition in which inadequate amount of oxygen is available to cells
• most common symptoms of hypoxia are:
• dyspnea
• elevated blood pressure with small pulse pressure
• increased respiratory and pulse rates
• pallor
• cyanosis
• hypoxia is often caused by hypoventilation
• can be chronic
• manifested as altered thought processes, headaches, chest pain, enlarged heart, clubbing, anorexia, constipation, decreased urinary output, decreased libido, weakness, muscle pain

Regulation of Respiration:

• Respiratory center is located in the medulla oblongata
• it is stimulated by an increase in CO2 and hydrogen ions and, to a lesser degree, by decreased O2 in arterial blood
• chemoreceptors in aortic arch and carotid bodies are sensitive to arterial blood gas levels and blood pressure and can activate the medulla
• proprioceptors in muscles and joints respond to body movement and can increase ventilation
• Stimulation of medulla increased rate and depth of ventilation to blow off CO2 and hydrogen and increase O2
• if a condition causes a chronic change in O2 and CO2 levels, the chemoreceptors may become desensitized and not regulate ventilation adequately

CV System and Transport of Gases:
For oxygen and carbon dioxide to move though out the body an adequately functioning cardiovascular system is vital.

• The cardiovascular system is composed of:
• heart and blood vessels
• atria- receive blood from veins
• ventricles- receive blood from atria and force blood to to the body and lungs
• one way valves that direct flow are locate at entrance and exit of each ventricle (mitral, tricuspid, pulmonary and aortic)
• I'm not going to go into the flow of blood here because I understand it, but if you have questions, I'm happy to explain!

• Oxygen is carried via plasma and red blood cells
• although O2 is dissolved in the plasma, the majority (97%) is carried by red blood cells
• oxyhemoglobin
• Internal respiration must occur
• internal respiration is the exchange of O2 and CO2 between circulating blood and tissue cells
• any abnormality in blood's constituents can change internal respiration, i.e. ;
• hemmorhage or loss or blood can decrease CO
• decrease in CO causes decrease in circulating blood that is able to deliver O2
• Anemia, decrease in red blood cells, results in insufficient hemoglobin available to transport O2

Factors Affecting Respiratory Function:
7 Major Factors that Affect Respiratory Function

Level of Health:

• Acute and chronic illness can affect respiratory function
• pts with renal and cardiac have compromised resp function bc of fluid overlaid and impaired tissue perfusion
• pt with chronic illness often have muscle wasting and poor tone
• Anemia can lead to impaired gas exchange
• MI causes lack of blood to heart. Damaged tissue results in less effective contractions and decreased perfusion and gas exchange
• scoliosis- air trapping
• Obesity- lack of exercise, decreased inflation at base of lungs, chronic bronchitis

Developmental Considerations:

Neonates and Infants:

• lungs transition from fluid filled to air filled
• airways are short and aspiration is a potential problem
• RR is rapid
• surfaactant is formed in utero at 34 to 36 weeks
• synthetic surfactant can be given
• respiratory activity is primarily abdominal

Toddlers, Preschoolers, School Aged and Adolescent:

• preschool child's eustachian tubes, bronchi, and bronchioles are elongated and less angular 
• number of colds increases as child enters preschool or daycare and is exposed to pathogens
• encourage good hand hygiene
• many children have cold or ear infections and upper resp infections
• by end of late childhood, immune system is more developed

Older Adults:

• airways become less elastic
• respiratory muscles are less effective
• airways collapse more easily
• increased risk for PNA and other infections

Medications:

• pts receiving drugs that affect the CNS need to monitored for respiratory depression or arrest
• opioids depress the medullary respiratory center

Lifestyle:

• sedentary activity patterns do not encourage expansion of alveoli
• people who exercise respond better to respiratory stressors
• cigarette smoking is the most important risk factor for COPD

Environment:

• high correlation between air pollution and lung disease
• occupational exposure to asbestos, silica, coal dust, can lead to chronic pulmonary disease

Psychological Health:

• those responding to stress may experience hyperventilation
• can lead to lowered CO2
• can develop anxiety as response to hypoxia

The Nursing Process for Oxygenation:

Nursing History:

• nursing hostly always contains a respiratory component
• Before starting the interview make sure pt is not in resp distress
• if pt is in distress, postpone interview and help pt
• If no emergency interventions are needed, obtain comprehensive history

Physical Assessment:

Inspection:

• inspect chest contour and shape
• slighlyt convex with no sternal depression
• infants chest wall is thin so ribs, sternum , an dxyphoid process are easily seen
• fat and muscle development is more noticeable in preschool
• ratio of transverse to AP diameter equals adult configuration of 1:2 by 6 years of age
• kyphosis contributes to leaning forward appearance
• observe respiratory rate and depth for one full minute
• normal respirations are quiet and unlabored
• note any flaring, retraction, tachypnea, or bradypnea- any of which would require further evaluation

Palpation:

• Palpate trachea (should be midline) and assess skin temp
• Ensure thoracic excursion is symmetrical
• Assess tactile fremitus (the capacity to feel sound on the chest wall)
• ask pt to repeat multi syllable word and feel for vibration
• increased fremitus occurs in pts with PNA bc of consolidation
• pts with CPOD have decreased fremitus bc air does not conduct sound well

Auscultation:

• Using diaphragm of stethoscope move from apex to base of lungs comparing one side to the other
• Normal breath sounds include vesicular, bronchial, and bronchovesicular
• If abnormal breath sounds are heard, ask the pt to cough and then reassess
• Adventitious breath sounds are abnormal breath sounds. They include:
• Crackles- 
• popping sounds heard usually on inspiration
• produced by fluid in airway or alveoli and opening of collapsed alveoli
• occur due to inflammation or congestion
• associated with pneumonia, CHF, bronchitis, COPD
• fine or coarse
• Wheezes-
• continuous sounds produced as air passes through constricted airways, narrowings, secretions, or around obstructions
• sibilant- high pitched
• sonorous- low pitched
• Pleural Friction Rub-
• continuous dry grating sounds caused by inflammation of pleural surfaces

Common Diagnostic Tests:

Pulmonary Function Studies:

• group of tests that evaluate respiratory status and detect abnormalities
• evaluate lung dysfunction
• diagnose disease
• assess disease severity
• assist in management of disease
• evaluate respiratory interventions

Spirometry:

• measure volume of air in liters exhaled or inhaled over time

Peak Expiratory Flow Rate:

• refers to point of highest flow during expiration
• reflects changes in size of airways 
• measure using peak flow meter
• repeated three times, highest flow recorded
• normal values are established in relation to height, weight, and gender

Diagnosing:

Examples of NANDA Nursing Diagnoses

• Ineffective Airway Clearance
• thick yellow secretions, fever, fatigue, dehydration, poor nutrition
• "I never feel as though I get enough air."
• 20 year hx of COPD with recent development of PNA
• pale skin with circumoral cyanosis
• increased RR
• coarse crackles
• productive cough
• Impaired Gas Exchange
• smoker, works around harmful chemicals, has had cold for 7 days
• cyanosis
• pursed lip breathing
• altered blood gases showing acidosis
• shortness of breath, nausea, ankle edema
• Ineffective Breathing Pattern
• anxiety 
• hyperventilating, tachypneic

Promoting Optimal Function:

• Cigarette smoking is the most important risk factor for pulmonary disease
• increases airway resistance
• reduces ciliary action
• increases mucous production
• causes thickening of alveolar-capillary membrane
• cause bronchial walls to thicken and lose the elasticity
• these effects occur in smoker and in those who live with smokers
• Reducing Anxiety
• Maintaining Good Nutrition
• people who work hard at breathing often do not have energy to eat and use a lot of their energy to breathe
• many medications and cause anorexia and nausea
• assess nutrition by measuring pts height, weight, upper arm circumference, serum protein levels, and nitrogen balance
• consider more frequent small meals over less frequent large meals
• meals should be eaten one to two hours after breathing treatments and exercise
• Pts with COPD require high protein/calorie diet to counter malnutrition
• encourage obese pts to use calorie controlled diet
• eating and digestion require energy which requires oxygen so remind pts to keep supplemental O2 on while eating
• Maintaining adequate fluid intake
• to help keep secretions thin pts should drink 2-3 liters of fluid daily
• increased in pts with fever, are breathing through mouth, coughing, or losing excessive body fluids in other ways
• Providing Humidified Air

Using Cough Medications:

• Expectorants are drugs that facilitate removal of respiratory tract secretions by reducing the viscosity of the secretions
• pts with extremely thick secretions may need them thinned for their cough to be effective, so a nonproductive cough can become productive

Cough Suppressants:

• drugs that suppress the cough reflex
• codeine is the preferred cough suppressant ingredient
• codeine can cause drowsiness
• a suppressant that does not cause drowsiness is dextromethorphan, which can be found OTC
• medicatiosn to suppress a cough are usually not recommended unless the patient is unable to sleep. If a productive cough is suppressed, secretions can be retained, leading to pulmonary infections

Lozenges:

• lozenges can be used to relieve mild, nonproductive, coughs in people without congestion
• control coughs by anesthetic benzocaine

Teaching About Cough Meds:

• cough meds are ready available
• consumers often take excessive amounts of more than one kind
• teach about appropriate choice of expectorants and suppressants
• cough syrups with high sugar or alcohol content can cause problems for diabetes pts lead to relapse in alcoholics
• meds containing antihistamines can have anitcholinergic action and cause problems for pts with glaucoma or urinary retention in men with prostate enlargement

Suctioning the Airway:

• If pt is unable to clear secretions with coughing, aspirate secretions with sxn device
• frequency of sxn'ing varies with amount of secretions present
• sxn'ing removes O2 from resp tract and can cause hypoxemia
• preoxygenate pt before sxn'ing
• possible complications of sxn'ing include
• infection
• arrhythmias
• hypoxia
• mucosal trauma
• death
• continuously monitor pt color and heart rate
• monitor color, consistency, and amount of secretions
• Stop sxn'ing immediately can call MD if:
• cyanosis
• excessively slow or rapid heart rate
• suddenly bloody secretions

Meeting Respiratory Needs with Medications:

• While nurses may not administer the inhaled meds they are involved in monitoring pts response and development of side effects
• encourage pts receiving inhaled meds to avoid caffeine, which may potentiate the side effects of bronchodilators

Administering Inhaled Medications:

• Inhaled meds may be administered to:
• dilate airways (bronchodilators)
• loosen thick secretions (mucolytics)
• reduce inflammation (corticosteroids)
• Nebulizers disperse fine particles of medication into the airway
• MDI delivers controlled dose with each actuation
• Mistakes with MDI's
• failing to shake canister before each use
• holding inhaler upside down
• inhaling through nose rather than mouth
• inhaling too rapidly
• stopping the inhalation when cold propellant is felt in mouth
• failing to hold breath after inhalation
• inhaling two sprays with one breath
• Dry Powder Inhalers
• breath activated
• quick deep breath activates flow of med
• eliminates need for coordination
• require less manual dexterity than MDI
• one disadvantage is meds can clump when exposed to humidity

Providing Supplemental O2:

• oxygen is considered a medication and must be ordered

Sources of Oxygen:

• wall outlet
• portable cylinder
• oxygen conectrators concentrate room air and are used in home care

Flow Rates:

• measured in liters per minute
• determines the amount of O2 delivered
• MD order prescribes flow rate

Humidification:

• used to prevent dryness and irritation of mucous membranes
• commonly used when oxygen is delivered at high rates

Precautions for O2 Administration:

• O2 is tasteless and colorless, combustible
• To prevent fires take following precautions:
• avoid open flames in pts room (no hibachi for dinner!)
• place no smoking signs
• check that electrical equipment works and doesn't spark
• avoid synthetic fabrics
• avoid oils

O2 Delivery Systems:

• Nasal Cannula:
• also called prongs
• does not impede eating or speaking
• easily dislodged
• can irritate nasal mucosa
• Nasopharyngeal Catheter:
• inserted through nose into oropharynx
• Face Mask:
• snug but not tight
• Most common types of face mask are:
• simple mask
• partial rebreather
• has reservoir and vents on side
• non rebreather
• delivers highest O2 via mask
• similar to partial exempt for two exhalation valves have one way valves
• venturi mask
• allows for delivery of precise concentrations 
• connected to O2, humidifier, flow meter
• never apply mask with flow rate <6 lpm
• Oxygen tent
• covers pts head and thorax
• does not allow for precise oxygen concentration

Oxygen Therapy in the Home:

• liquid oxygen and oxygen concentrator are most common in the home
• Oxygen concentrators remove nitrogen from air an concentrate O2
• needs a power source
• portable, cost effective, easy to use
• cannot run @ > 4lpm

Managing Chest Tubes:

• Pts with pleural effusion, hemothorax, or pneumothorax require a chest tube to drain these substances and allow the lung to re-expand
• Chest tube is inserted in pleural space
• covered with air tight dressing
• may or may not be attached to sxn
• Other components of system may include:
• closed water seal drainage system that prevents air from reentering the chest
• suction control chamber that prevents excess sxn pressure from being applied to pleural cavity
• Placement of tube is determined by the type of drainage
• tube placed higher to drain air
• lower to drain fluid
• Nursing responsibilities include assisting with insertion and removal of tube
• Once tube is in place:
• monitor respiratory status
• check the dressing
• maintain patency and integrity of drainage system

Using Artificial Airways: