OXYGENATION;
RESPIRATORY & CIRCULATORY FUNCTION
LEARNING OBJECTIVES:
1. Describe the basic physiological mechanisms of ventilation, circulation
and oxygenation;
2. Discuss the factors affecting oxygenation and the physiological responses
to reduce oxygenation;
3. Assessment of the ventilatory, circulatory and oxygenation status
4. Identify oxygenation problems
5. Determine plan of care & goals for oxygenation problems
6. Discuss implementation of specific interventions
7. Evaluate outcomes of specific interventions
Introduction
• Oxygenation
• Delivery of O2 to body’s tissues and cells
• Mechanisms of oxygenation
• Ventilation
• Alveolar Gas Exchange
• Oxygen Transport
• Delivery to tissues
• Cellular Respiration
Physiology of Oxygenation
• Ventilation
• 1st step
• Movement of air into and out of the lungs
• Regulated by pons and medulla oblongata
• Rate and depth of RR is dependent to concentration of H+
(pH) and CO2
Physiology of Oxygenation
• Alveolar gas exchange
• 2nd step
• Starts once air reaches the alveoli
• External respiration (O2 uptake) occurs
Physiology of Oxygenation
• Oxygen Transport & Delivery
• 3rd step
• Once oxygen diffuses into blood, it is delivered to each cell
(systemic circulation)
• 3 factors that influence the transport
• Amount of dissolved oxygen in plasma
• Amount of hemoglobin
• Tendency of the hemoglobin to bind with oxygen
Physiology of Oxygenation
• Oxygen in blood is measured in 2 ways
• O2 in plasma is expressed as Partial pressure of O2
• PaO2=80-100 mmHg
• O2 bound to Hgb is expressed as percentage of Hgb
saturated w/ O2
• SaO2=96-98%
• O2 bound to Hgb is delivered to cells of the body by
process of circulation!
Physiology of Oxygenation
• Circulation
• A function of the heart and blood vessels
• Cardiac cycle
• Produced by electrical and mechanical events
• Cardiac conduction system
• One cycle of atrial and ventricular contraction and relaxation
which occurs in sequence
Physiology of Oxygenation
• Cellular respiration
• 4th step
• Gas exchanged at the cellular level is the same w/ the
alveolar level
• Occurs via diffusion
• Internal respiration
Factors Affecting Oxygenation
• Age
• Older adults
• Barrel chest
• Respiratory infections
• Environmental and lifestyle
• Tobacco smoke, smog, dust, animal dander, toxic chemicals
• Disease process
Factors Affecting Oxygenation
• Disease process
• Obstructive pulmonary diseases
• Airway becomes partially or completely blocked
• Diminished airflow
• Decreased elastic recoil
• Results in air trapping and impaired exhalation
• COPD conditions
• Asthma, emphysema, chronic bronchitis
Factors Affecting Oxygenation
• Disease process
• Restrictive pulmonary diseases
• Impaired ability of the chest wall & lungs to expand during the
inspiratory phase
• Impaired breathing
• Impaired airflow to alveoli
• Pneumonia, pulmonary fibrosis
• Smoking, immunosuppressed, unconscious
• Traumatic injuries to the thorax
• Rib fractures
• Flail chest (inward chest mov’t during inhalation)
• Pleural defects
Factors Affecting Oxygenation
• Disease process
• Restrictive pulmonary diseases
• Pleural defects
Pleural Defect Description Symptoms
Pleural Effusion Fluid in pleural layers Cough, chest pain, DOB
Hemothorax Blood in pleural layers Dyspnea, hypotension
Pneumothorax Air in pleural layers Dry hacking cough, etc.
Tension Pneumothorax Lung & heart compression Tachypnea, Tachycardia, leading to shock
• Atelectasis
• Collapse of alveoli in the lungs
Factors Affecting Oxygenation
• Disease process
• Diffusion defects
• Decrease in efficiency of gas diffusion
• May occur w/ OLD or RLD
Circulatory Influences on Oxygenation
• Ventilation-perfusion mismatching
• Atherosclerosis
• Heart failure
Circulatory Influences on Oxygenation
• Ventilation-perfusion mismatching
• Also termed as V/Q mismatching
• Due to
• Alterations in position & the effect of gravity
• Better ventilation or perfusion in certain zones of lung tissue
• Vasoconstriction or bronchoconstriction as compensatory
mechanism for the V/Q mismatch
• If V/Q mismatch is not overcome by compensatory mechanism
• Deadspace
• Alveoli are well-ventilated by O2 but poorly perfused by blood
• Shunting
• Alveoli are poorly ventilated by O2 but well-perfused by blood
Circulatory Influences on Oxygenation
• Atherosclerosis
• Narrowing and eventual occlusion of the lumen of arteries
by lipid, fibrin and calcium deposits on the interior walls of
arteries
• This reduces blood flow and O2 to tissues which leads to
tissue ischemia and tissue necrosis
• Ex.
• CHD leads to myocardial infarction
• CVD leads to CVA or stroke
Circulatory Influences on Oxygenation
• Heart failure
• A condition in which the heart is unable to pump enough
blood to meet the metabolic needs
• Ex.
• Left-sided heart failure
• Shock or hemorrhage
• Pulmonary edema
Oxygen-carrying Capacity Of Blood Influences Oxygenation
• Alteration in hemoglobin
• A deficiency in Hgb decrease O2 carrying capacity
• Ex. Anemia
• Alteration in O2 uptake
• Certain conditions impair the ability of the cells to take up
and utilized O2
• Ex. Cyanide poisoning, sepsis
Physiological Responses to Reduced Oxygenation
• Increased O2 extraction • Tissue ischemia and cell
• Anaerobic metabolism death
• Response to high altitude • Carbon dioxide transport
• Less O2 in high altitude and excretion
• Acute response • Glucose metabolism will
• Increased ventilation rate and release CO2
depth • Lungs will release CO2 in the
• Irregular breathing patterns alveoli by diffusion
• Chronic response • CO2 will function in acid-base
• Increased production of balance
erythropoietin
• Reduced cellular O2 • CO2 will increase in tachypnea
requirement and hypercapnia
Respiratory Assessment
• Purpose fingers, chest configurations,
• To identify people who have signs of hypoxia, breathing
patterns
potential or actual alterations • Palpation
in oxygenation • Vocal fremitus, tracheal
• Basis of assessment displacement, cold, clammy
• Health hx (COLDSPA) skin
Cough, sputum, SOB, pain • Percussion
•
Hyperresonance, dull
PE
•
•
percussion tone, lung
• Inspection consolidations
• Effort at ventilation, • Auscultation
distressed appearance, • Adventitious sounds
flaring of nostrils, position
preferences, clubbing of
Diagnostic and Laboratory Data
• Ventilation Function Studies
• Measures person’s breathing
• Spirometry
• Measure the speed and ease of airflow through the airways
• Pulmonary function studies (PFS)
• Determine the volume of air in the lungs
Diagnostic and Laboratory Data
• Sputum
• Check for blood, particulate matter, malignant cells
Sputum Color Pathology
Mucoid, white Tracheobronchitis, Asthma, viral
infection
Yellow or Green Bacterial infection
Rusty or blood-tinged Pneumonia, TB
Black Lung disease
Pink Pulmonary edema
Diagnostic and Laboratory Data
• Hematology
• Lactic acid, Hgb and Hct
• Necessary in determining the effectiveness of oxygen
delivery to tissues & cells
• Venous blood gases
• Easy to obtain
• Also useful in assessing oxygenation
Diagnostic and Laboratory Data
• Blood enzymes
• Diagnose the degree of tissue damage
Isoenzyme Normal Ranges Tissue Source
CPK (BB) 0% Brain & Lung; elevation
(CVA & Lung Damage)
CPK (MB) 0-4% Myocardium; elevation
(MI)
CPK (UU) 96-100% Skeleton & Myocardium;
elevation (skeletal muscle
disorder)
Diagnostic and Laboratory Data
• Blood enzymes
• Diagnose the degree of tissue damage
Isoenzyme Normal Ranges Tissue Source
LDH1 17-27 Heart, kidneys, RBC
LDH2 29-39 Heart, kidneys, RBC
LDH3 19-27 Lungs, Pancreas, Thyroid,
Adrenal
LDH4 8-16 Liver, skeletal tissue
LDH5 6-16 Liver, skeletal tissue
Diagnostic and Laboratory Data
• Blood lipids
• Determine total blood cholesterol
• Helpful in diagnosing CVD’s and CHF’s
Lipid Normal
Cholesterol <5.17mmol/L
LDL Chole <3.36mmol/L
HDL Chole >1.03mmol/L
Triglyceride <2.82mmol/L
Diagnostic and Laboratory Data
• Arterial puncture
• Done to assess arterial blood gases (ABG)
• ABG
• Reveals ability of the lungs to exchange gases
• Partial pressure of O2 (PaO2)
• Partial pressure of CO2 (PaCO2)
• pH of arterial blood
Diagnostic and Laboratory Data
• ABG ranges
Measurement Normal Values Significance
pH 7.35-7.45 Acid-base balance
PaCO2 35-45mmHg Adequacy of alveolar
ventilation
HCO3 22-26mEq/L Metabolic component
PaO2 80-100mmHg Oxygen dissolved in
plasma
SaO2 96-98% Saturation of Hgb with O2
Diagnostic and Laboratory Data
• Pulse oximeter study
• Uses light waves to measure • Determine abnormalities of
arterial blood oxygen thoracic structures
saturation • Endoscopic procedures
• Radiologic studies • Bronchoscopy
Examines the bronchus and
(‘roentgenogram’)
•
bronchial tree
• Uses external beams to • Aspiration studies
examine hard and soft tissues • Thoracentesis
of the body • Aspiration of fluid from the
• Chest xray pleural cavity
• The most common radiologic
Problem Identification
• Ineffective airway clearance of O2 to tissues
• Exists when the person has • Ineffective tissue perfusion
difficulty maintaining a patent • Widespread condition in the case of
airway decreased CO
• Ineffective breathing patterns • Activity intolerance
• A common problem in pts w/ RLDs, • Impact of illness on the person’s
CNS disorders, neuromuscular ability to perform ADLs
diseases, underwent a major • Anxiety
abdominal or thoracic surgery • A prominent finding in individuals
• Impaired gas exchange experiencing breathing difficulties
• Occurs as a result of V/Q mismatch
• Decreased cardiac output
• This condition impairs the delivery
Implementation
• Interventions to promote airway clearance
• Teach effective coughing
• To prevent pulmonary complications
• Huffing
• Initiate postural drainages and CPT
• To promote drainage secretions from lungs
• Involves positioning, percussion, vibration
• Monitor hydration
• Promote thinning of secretions to easily expectorate
Implementation
• Interventions to promote airway clearance
• Administer Medications
• Assists in airway clearance
• Expectorants, mucolytics, bronchodilators
Medication Type Examples Actions
Beta-Adrenergic Epinephrine, albuterol, Causes bronchial relaxation
Terbutaline
Corticosteroid Beclomethasone, Prednisone Anti-inflammatory
Mast cell Stabilizer Spinhaler Prevents histamine release
Methylxanthine Aminophylline Bronchodilator
Implementation
• Interventions to promote airway clearance
• Introduce artificial airways
• Used in people w/ significant airway obstruction
• Nasal airways, Guedel’s oral airway, ET tubes
• Suction Airways
• May be necessary to clear secretions
Implementation
• Interventions to improve O2 uptake and delivery
• Oxygen administration
• Increase O2 concentration can increase O2 uptake in the
pulmonary capillary
• Administration of blood components
• Indicated on pts w/ decreased circulating blood volume,
decreased Hgb, hemorrhage
Implementation
• Interventions to increase CO and tissue perfusion
• Manage fluid balance
• Cornerstone in the care of pts w/ reduced CO
• Fluid and Na restrictions, I&O monitoring, daily weight monitoring
• Activity Restrictions
• To reduce the workload of the heart
• Proper Positioning
• To decrease the fluid load to the heart, prevent pulmonary edema
• Ie. Elevated head and upper body
• Administer medications
• Improve CO and perfusion
• Increase cardiac oxygen supply and reduce myocardium’s demand
for O2
Implementation
Medication Examples
Diuretic Furosemide, Spironolactone
Cardiac Glycoside Digoxin
Inotropic agent Dobutamine
Antihypertensive ACE inhibitors, beta blockers,
calcium channel blockers
Vasodilators Hydralazine
Nitrate Isosorbide dinitrates
Implementation
• Emergency interventions
• Remove airway obstruction
• Back blows or chest thrusts
• Initiate CPR
• Artificial support of circulation and ventilation
References:
DeLaune, Sue, Ladner, Patricia, Mctier, Lauren, Tollefson, Joanne,
2024, Fundamentals of Nursing, Cengage Learning Asia Pte. Ltd.
(Philippine Branch), pages 813-848
