NURSING 201 Oxygenation Study Guide Complete
The Concept of Oxygenation
• Oxygenation: the process of providing oxygen to all cells of the
... [Show More] body
• Function of respiratory system:
o Obtain oxygen from atmospheric air
o Transport air through respiratory tract to alveoli
o Diffuse oxygen into the blood to be carried to all cells of the body.
• Respiratory system function achieved through ventilation:
o Inspiration (inhaling): oxygen carried to alveoli where exchanged for CO2
o Expiration (exhaling): CO2 is expelled from the body
• Respiration: exchange of oxygen and carbon dioxide at the cellular level
o Term is commonly used synonymously with ventilation
• Breathing is typically an autonomic process
o Alterations in breathing patterns should be immediately addressed
Physiology Review
• Upper respiratory system:
o Inlet for air into the body
o Nose is typically the primary entry for air
▪ Two nares, which warm, humidify, filter air as it is breathed into the nose
• Protective mechanisms:
o Sneezing
o Cilia
o Breathing through the mouth
• Lower respiratory tract:
o Enclosed in the neck, thoracic cavity
o Trachea: entrance for air into the lungs
o Muscular structures of neck relaxed during breathing
o Chest rises and falls effortlessly and symmetrically with each breath
• Trachea bifurcates into two bronchi to access right and left lungs
o Right bronchus shorter than left
o Bronchi divide into bronchioles
o Trachea, bronchi supported by cartilage rings
o Bronchioles supported by smooth muscles
• Alveolar ducts branch into alveolar sacs, made up of individual alveoli
• Alveoli are the sites for gas exchange:
o Oxygen diffuses across membranes into blood
o Carbon dioxide diffuses into the alveoli
o Surfactant keeps alveoli from collapsing
• Lungs:
o Right lung: three lobes
o Left lung: two lobes
o Inferior lobes are the largest
o Each lung has pleural lining:
▪ Aids respiration
▪ Separates lungs
▪ Two layers:
▪ Visceral pleura covers the surface of each lung
▪ Parietal pleura lines the inside of chest wall
▪ Pleural space: the region between them
• Drive to breathe depends on level of CO2 in arterial blood
o When level rises, receptor sites in medulla and pons stimulate increase in rate and/or depth of ventilation
• Eupnea: breathing within the expected respiratory rates
o Newborns: 20-80 bpm
o Infants: 30-60 bpm
o Toddlers: 20-40 bpm
o Preschoolers: 22-34 bpm
o School-age children: 12-25 bpm
o Adolescents: 12-20 bpm
o Adults: 12-20 bpm
o Older adults: 15-20 bpm
• Quality of breathing: effort involved in taking a breathe, sounds that are involved
• Effective breathing requires a patent airway
• Drive to breathe depends on CO2 in arterial blood
• Nature and quality of breath sounds:
o Bronchial sounds: loud, high-pitched, heard over trachea
▪ Longer on exhalation than inhalation
o Bronchovesicular sounds: medium in loudness and pitch, heard on each side of the sternum, between scapulae
▪ Equal in duration during inhalation and exhalation
o Vesicular sounds: soft, low-pitched, heard over peripheral lung fields
▪ Most prominently heard in lung bases
▪ Typically longer on inhalation than exhalation
• Receptor sites in aortic arch and carotid arteries monitor O2 levels
o Induce inspiration when level falls below normal
• Stretch receptor sites in lungs control volume of air inhaled with each breath
• Ability of respiratory system to deliver O2 depends on:
o Inflated, well-oxygenated alveoli
o Well-perfused capillaries
• Movement of O2 across alveolar-capillary membrane into capillary is represented by ventilation-perfusion (V-Q) ratio
o Concentration of O2 and CO2 that dictate movement of each gas
Alterations to Oxygenation
• Hypoxemia: decreased level of O2 in blood
o Left untreated, can result in hypoxia: decreased delivery of O2 to tissues
• Mild impairments in oxygenation can cause:
o Fatigue
o Irritability
o Discomfort
• More severe alterations can be fatal if left untreated
Alterations and Manifestations
• Alterations in oxygenation described in context of:
o Gas exchange: COPD, retractions, cyanosis, VQ abnormalities
o Airway patency: secretions, inflammation, obstruction
o Respiratory patterns: tachypnea, hyper/hypoventilation, dyspnea, orthopnea, respiratory depression, Kussmaul respirations, Cheyne-stokes
• Damage to supporting thoracic structures can interfere with effective respiration –
pneumothorax (spontaneous, tension)
• Irritation or inflammation of respiratory mucosa affects oxygenation
• Gas exchange:
o Respiratory drive primarily stimulated by concentration of H+ in arterial blood
o Concentration varies in direct response to arterial blood concentration of CO2
o Increase in H+ leads to increase in CO2
o Decrease in H+ leads to decrease in CO2
o Blood pH increases
o Healthy respiratory system compensates by increasing/decreasing rate and/or depth of respirations
o Chronic Obstructive Pulmonary Disease (COPD)
▪ Alveolar damage limits exchange of O2 and CO2
▪ CO2 retention, decrease in blood O2 levels
▪ Retractions, cyanosis
▪ Clubbed nail beds
• Alterations in V-Q ratios may result in inadequate oxygenation of body cells
o Airflows in alveolus blocked:
▪ Sputum
▪ Inflammation/swelling
▪ Atelectasis [Show Less]