OXYGENATION

Structure and Function of the Respiratory System

Structure

Upper Respiratory Tract (Upper Airway):
- Nose and nasal cavity
- Pharynx:
  - Oropharynx
  - Nasopharynx
  - Laryngopharynx
Lower Respiratory Tract (Lower Airway):
- Larynx or voice box
- Trachea
- Bronchi (left and right)
- Bronchioles (terminal and respiratory)
- Alveoli or air sacs

Function

Pulmonary Ventilation:
- Accomplished through breathing.
- Cycle includes inhalation (inspiration) and exhalation (expiration).
Factors Affecting Adequate Ventilation:
- Clear airways
- Cough reflex
- Ciliary action
- Edema/inflammation and spasms of the airway
- Intact CNS and respiratory center (medulla and brainstem)
  - Altered by trauma, opiates, or drugs
- Intact thoracic cavity in response to pressure changes
  - Intrapleural pressure: pressure in the pleural cavity surrounding the lungs
  - Intrapulmonary pressure: pressure within the lungs
  - Intactness of the diaphragm and use of accessory muscles for respiration
- Adequate pulmonary compliance and recoil
  - Lung compliance: the expansibility or stretchability of lung tissue; decreases with aging
  - Atelectasis: lung collapse
  - Lung recoil: the continual tendency of the lungs to collapse away from the chest wall
  - Surfactant: increases lung surface tension

Common Causes of Atelectasis

Hypoventilation
Compression
Airway Obstruction

Alveolar Gas Exchange

Diffusion: Transfer of solute particles from an area of higher concentration to lower concentration.
Transport of Oxygen and Carbon Dioxide:
- 97% of oxygen combines with hemoglobin to form oxyhemoglobin.
- Remaining oxygen is dissolved in plasma and cells.
- Factors affecting the rate of transport (from lungs to cells):
  - Cardiac output
  - RBC count and hematocrit
  - Exercise
Carbon Dioxide:
- 65% is carried by RBC as bicarbonate (HCO3).
- 30% combines with hemoglobin to form carboxyhemoglobin or carbaminohemoglobin.
- 5% is transported in plasma and as carbonic acid.
Regulation of Respiration:
- Neural and chemical control to maintain correct concentrations of O2 and CO2 in the blood.
- Respiratory centers: Medulla and pons.
- Chemoreceptors:
  - Central (Medulla): highly sensitive to increases in CO2 in blood; strongest stimulus.
  - Peripheral (carotid and aortic): sensitive to decreases in O2 in blood.

Factors Affecting Respiration

Age:
- Newborns: draining of fluids in lungs, increase in PCO2, first breath, full inflation by 2 weeks.
- Elderly: changes of aging that affect the respiratory function:
  - Chest wall and airway become rigid and less elastic.
  - Amount of exchanged air is decreased.
  - Cough reflex and ciliary action decrease.
  - Decrease in muscle strength and endurance.
  - Decrease in efficiency of immune system, more prone to infections.
  - GERD is more common, leading to aspiration.
Environment:
- Altitude: higher altitude = less oxygen = increased respiratory rate and depth.
- Heat and cold
- Air pollution
Lifestyle:
- Physical exercise and activity increases respirations.
- Sedentary lifestyle: lesser alveolar expansion and deep breathing patterns.
Health Status:
- Healthy: sufficient oxygen delivery and supply.
Medications:
- Decrease rate and depth of respirations: depressants, narcotics, anti-anxiety drugs.
Stress:
- May cause hyperventilation.
- Release of Epinephrine: bronchodilation.

Alterations in Respiratory Function

Respirations can be altered by conditions that affect:
- Movement of air in and out of lungs.
- Diffusion of oxygen and carbon dioxide between lungs and blood.
- Transport of oxygen and carbon dioxide via blood to and from the cells.
Hypoxia:
- Condition of insufficient oxygen in the body.
- Adequate O2 is needed for brain function.
- 3-5 minutes of hypoxia can be tolerated before permanent brain damage occurs.
- Hypercarbia/ hypercapnia: accumulation of CO2 in blood.
- Hypoxemia: decreased O2 in cells.
- Cyanosis: bluish discoloration of skin, nail beds, and mucous membranes.

Clinical Manifestations of Hypoxia

Rapid pulse
Rapid, shallow respirations and dyspnea
Increased restlessness or lightheadedness
Flaring of nares
Substernal or intercostals retractions
Cyanosis

Conditions That Can Lead to Hypoxia

Hypoventilation
Decreased diffusion of O2 and CO2 as in pulmonary edema
Problems with the delivery of oxygen such as anemia, heart failure, embolism

Altered Breathing Patterns

Refers to rate, volume, rhythm, and relative ease and effort in respirations.
Eupnea: normal; quiet, rhythmic, and effortless.
Tachypnea: increased rate.
Bradypnea: decreased rate.
Apnea: absence or cessation of respirations.
Hyperventilation: increased rate and depth.
Hypoventilation: decreased rate and depth.
Cheyne-Stokes respirations: marked rhythmic waxing and waning from very deep to very shallow to temporary apnea.
Biot's respirations: shallow breaths interrupted by apnea.
Kussmaul's respirations: fast and deep breaths like sighs with no expiratory phase.
Orthopnea: inability to breath except in upright position.
Dyspnea: difficulty of breathing.

Obstructed Airways

Complete: complete obstruction of any part of the airway.
- Heimlich maneuver (if client is conscious); chest or abdominal thrust (unconscious patient); chest thrust and back blows (infants).
Partial: partial obstruction of any part of the airway; assist the client to cough.

Assessment of Respiratory Function

Diagnostic Studies

Pulse Oximetry:
- Measures oxygen saturation of hemoglobin.
- Normal range: 90-100%.
Arterial Blood Gas Analysis:
- Measures concentrations of blood gases and identifies acid-base balance of the body.
- Requires arterial blood sample.
Pulmonary Function Test:
- Measures lung volumes and capacity.
- Performed by respiratory therapists; painless; client will breathe into a machine.

Lung Volumes and Capacities

Tidal volume (VT): volume of inhaled and exhaled during normal and quiet breathing.
Inspiratory reserve volume (IRV): maximum amount of air that can be inhaled over and above the normal breath.
Expiratory reserve volume (ERV): maximum amount of air that can be exhaled following a normal exhalation.
Residual volume (RV): amount of air remaining in the lungs after maximal exhalation.
Total lung capacity (TLC): total volume of lungs at maximum inflation; $VT + IRV + ERV + RV$
Vital capacity (VC): total amount of air that can be exhaled after a maximal inspiration; $VT + IRV + ERV$
Inspiratory capacity: total amount of air that can be inhaled following normal quiet respiration; $VT + IRV$
Functional residual capacity (FRC): volume left in the lungs after normal exhalation; $ERV + RV$
Minute volume (MV): total amount of air breathed in one minute.

Common Signs and Symptoms

Cough:
- Most common sign of respiratory disease.
- Caused by irritation of mucous membranes.
- Chief protection against accumulation of secretions and foreign body.
Chest pain:
- May indicate hypoxia or damage to lungs.
Cyanosis and Clubbing of fingers:
- Indicates hypoxia.
Hemoptysis:
- Blood expectorated from the respiratory tract; caused by trauma or break in the continuity of the respiratory tract.
Effort in breathing:
- Dyspnea or Orthopnea
Sputum production:
- Reaction of lungs to constantly recurring irritation.

Thoracic Sounds

Crackles: loud, low-pitched bubbling sound; results from air passing through fluid.
Wheezes: musical sound; caused by air passing through narrowed airways.
Stridor: loud, high-pitched crowing sound.
Friction rub: grating, loud harsh sound.
Ronchi: sounds like snores or moans.

Chest Configuration

Normal Adult AP: L= 1:2
Barrel chest: increase in AP diameter
Pigeon chest: increase in AP diameter; results from sternal displacement
Funnel chest: depression of lower portion of sternum

History

Current respiratory problems:
- Changes in breathing pattern
- Activities that may cause symptoms
- How many pillows used at night
History of respiratory disease
- Any respiratory diseases or infections
- Frequency of occurrence
- Exposure to pollutants
Lifestyle
- Smoking history
- Exposure to smoke and other respiratory irritants
- Alcohol use
- Exercise pattern
Presence of cough
- How often
- When does it occur
- Productive or dry
Description of sputum
- When it is produced
- Amount, color, thickness, odor
- Presence of blood
Presence of chest pain
- Location
- Description
- Does it occur with inspiration or expiration
- How long does it affect breathing
- Aggravating and alleviating factors.
Presence of risk factors
- History of respiratory diseases in the family
Medication History
- OTC prescriptions for breathing e.g. bronchodilators

Promoting Effective Respiratory Function: Promoting Oxygenation

Deep Breathing and Coughing
Hydration
Medications
Incentive Spirometry
Chest Physiotherapy
Oxygen Therapy

Promoting Oxygenation

Positioning the client to allow maximum chest expansion (Semi or High Fowler's position and Orthopneic position)
Encouraging or providing frequent changes in position
Encouraging ambulation
Implementing measures that promote comfort such as giving pain medications

Deep Breathing and Coughing

To remove secretions from the airways
Frequently indicated for clients with restricted chest expansion
- Breathing
  - Abdominal or Diaphragmatic Breathing
    - Permits deep full breaths with little effort
  - Pursed Lip Breathing
    - Helps client develop control over breathing

Instructions

Assume a comfortable position
Flex knees to relax abdominal muscles
Place both hands on abdomen
Breath deeply through the nose
Exhale through pursed lips counting to seven
- Coughing: Controlled and Huff coughing
  - After using bronchodilator, inhale deeply and hold breath for a few seconds
  - Cough twice (first: loosens secretions; Second: expels them)
  - Rest

Hydration

Maintains moisture of respiratory membranes
Inadequate hydration can cause the secretions to be thick and more difficult to expel
Humidifiers: add vapor to inspired air
Nebulizations: carries humidity and medications

Medications

Bronchodilators: Salbutamol
Anti-inflammatory drugs: Prednisone
Expectorants: Guaifenesin
Mucolytics: Carbocisteine
Cough suppressants (Antitussive): Codeine Sulfate

Phlegm Colors

White: may mean allergies or viral infection
Green: may mean bacterial infection
Red: may mean lung injury
Brown: may indicate lung disease or malignancy

Incentive Spirometry

Sustained Maximal Inspiration Devices
Measure the flow of air inhaled through a mouthpiece
Uses:
- Improve pulmonary ventilation
- Counteract the effects of anesthesia or hypoventilation
- Loosen respiratory secretions
- Facilitate respiratory gas exchange
- Expand collapsed alveoli

Chest Physiotherapy: Percussion, Vibration and Postural Drainage

Dependent functions
To remove secretions
Sequence: positioning, percussion, vibration, removal of secretions by coughing or suction
Important Nursing Considerations:
- Auscultate lungs before and after the procedure
- Administer bronchodilators before procedure
- Document color, amount and character of expectorated sputum
Best time: before breakfast, before lunch, in the late afternoon and before bedtime
- If done after meal (can be tiring and can induce vomiting)
Nursing considerations:
- Assess stability of vital signs (PR and RR)- to ensure tolerance of the patient
- Note for signs of intolerance such as pallor, diaphoresis, dyspnea, nausea
- Make appropriate adjustments to the positions as necessary

Percussion or Clapping

Forceful striking of the skin with cupped hands
Can mechanically dislodge tenacious secretions

Steps

Cover the area with a towel or gown to reduce discomfort
Ask the client to breathe slowly and deeply to promote relaxation
Alternately flex and extend the wrists rapidly to slap the chest
Percuss each affected lung segment for 1-2 minutes

Vibration

Series of vigorous quiverings produced by hands that are placed against the client's chest wall
Used after percussion to increase the turbulence of the exhaled air
Done alternately with percussion

Steps

Place hands, palms down, on the chest area to be drained, one hand over the other with the fingers together and extended
Ask the client to inhale deeply and exhale slowly through the nose and pursed lips
During exhalation, tense all the hand and arm muscles, and using mostly the heel of the hand, vibrate the hands, moving them downward. Stop when client inhales
Vibrate during five exhalations over one affected lung
After each vibration, encourage client to cough and expectorate secretions

Postural Drainage

The drainage by gravity secretions from various lung segments
Bronchodilators or nebulization therapy may be given before postural drainage
Scheduled 2 or 3 times a day depending on degree of lung congestion
Each position is usually assumed for 10-15 minutes

Oxygen Therapy

Prescribed by the physician; but can be given without order in emergency cases
Physician specifies method of delivery, liter flow per minute (LPM) and concentration of oxygen (Fi02: fraction of inspired oxygen)
Indications:
- Difficulty ventilating all areas of the lungs
- Impaired gas exchange
- Heart failure (MI)
- Hypoxia/ hypoxemia
Hazards or complications:
- Ventilatory depression
- Oxygen toxicity (Retrolental Fibroplasia: O2 toxicity in newborns) this can occur if the FiO2 given is >50% in a 24-hour duration
- Bacterial contamination: contaminated humidification system
- Skin irritation from device material
- Drying effect on the mucous membranes of respiratory tract: use humidifiers
Oxygen supply:
- Wall outlets
- Tanks and cylinders
- Portable oxygen cylinders

Types of O2 Delivery Systems

Low flow systems: will not meet the entire flow demand of the patient
- Nasal Cannula/ Nasal Prongs and Nasal Catheter
  - O2 concentration: 24-45% at flow rates 2-6L per minute
  - Advantages:
    - Most common and inexpensive device
    - Easy to apply
    - Does not interfere with the client's ability to talk or eat
    - Comfortable and allows freedom of movement
  - Disadvantages:
    - Inability to deliver higher concentrations of 02
    - Drying and irritating to mucous membranes
    - Can be easily dislodged
- Simple Face Mask
  - Covers the client's nose and mouth
  - 40-60% concentration at 5-8L per minute
- Partial rebreather mask
  - Same as non-rebreather mask but without valves
  - Allows the client to rebreathe about the first third of the exhaled air (the reservoir bag)
  - Increases the FiO2 by recycling oxygen
  - O2 concentration of 60-90% at 6-10L per minute flow
  - Nurse should not let the bag be totally deflated; if this occurs increase the flow rate
- Non-rebreather mask
  - Delivers highest O2 concentration as possible
  - Contains one-way valves which prevents the air room and client's expired air from entering the reservoir bag
  - Only oxygen in the bag is inspired again
  - Should not be totally deflated during inspiration to prevent CO2 build up; if it occurs increase flow rate
  - 95-100% concentration at 10-15L per minute flow
High flow systems: will meet the entire flow need of the patients
- Venturi mask
  - Has wide bore tubing and color coded jet adapters
  - Delivers 24-40% or 50% at 4-10L pr minute flow
  - Color coded adapters:
    - Blue- 24%
    - Yellow- 28%
    - Green- 35%
    - Peach-40%
    - White-31%
    - Orange- 50%

Nursing Considerations for Oxygen Therapy

Humidifiers as needed. Do not give at liter flows of less than 2
Fire safety: oxygen is highly combustible
- Place