Respiratory System 4 Flashcards
What is spirometry?
This is a test used to assess pulmonary function
It provides information about lung volumes and capacities
This information can be used to identify patients with obstructive diseases, restrictive diseases or normal lung function
What is tidal volume?
The volume of air inhaled or exhaled with each normal breath
What is inspiration reserve volume(IRV)?
The volume of air inhaled at the end of a normal tidal inspiration
What is expiratory reserve volume(ERV)?
The volume of air within the lungs that can be exhaled after the end of a tidal exhalation
What is the residual volume?
The air remaining in the lungs after a maximal expiration (this volume of gas cannot be expelled, and cannot be measured by spirometry)
What are functional Residual Capacity( FRC)?
The total volume of air remaining in the lungs at the end of a tidal exhalation
What is the function of total lung capacity(TLC) ?
The volume of air in the lungs at the end of a maximal inspiration
What is a vital capacity(VC)?
The volume of air exhaled from maximal inspiration to maximal exhalation; maximum expiration. When done with force this volume is termed the forced vital capacity (FVC)
What is forced expiratory volume in 1 second (FEV1)?
The volume of air exhaled in the first second of a FVC second
What is an obstructive disorder?
- Expiratory flow rate is significantly decreased resulting in decreased FEV 1 and FVC
- The FEV1/FVC ratio is low
What is a restrictive diso4der?
- Lung inflation is decreased resulting in decreased FEV 1 and FVC
- The FEV1/FVC ratio is normal or increased
What is Forced expiratory flow (FEF25-75)?
Forced expiratory flow
- Represents the expiratory flow rate over the middle half of the FVC (between 25% and 75%)
- Small airway obstruction may be present even when the FEV1/FVC % is above the lower limit of normal
- FEF25-75 has the greatest sensitivity for the detection of early airflow obstruction
How much is FEV 1 normally?
Normally FEV 1 should be about 80% of total volume expired(FVC)
FEV1/FVC ratio= 4.5 L/5.5 L*100= 80%
Differentiate restrictive and obstructive in the flow/volume loop
Obstructive loop- scooped out appearance common in emphysema
Restrictive loop- steep expiratory limb
Differentiate restrictive and obstructive pulmonary diseases
Obstructive- expiratory flow rate is decreased,
Restrictive- lung inflation is decreased
Obstructive- airway occlusion, air trapping
Restrictive- intrinsic- lung tissue, extrinsic- chest wall, pleura or neuromuscular
Give examples of obstructive diseases
- Obstructive Bronchitis
- Emphysema
- Asthma
Give examples of restrictive disease
- pulmonary fibrosis
- IRDS
- Scoliosis
What is COPD?
Chronic obstructive pulmonary disease (COPD)
- Combination of chronic bronchitis, emphysema and asthma
- The most common chronic lung disease in the United States
- Commonly caused by cigarette smoking
- The classical feature is decreased airflow due to chronic obstruction of the small airways
- Results in a decrease in FVC, FEV1 and FEV1/FVC ratio
- In severe cases of air is trapped in the lungs during forced expiration
What is the partial pressure?
Atmospheric air= mixture of gases
Dalton’s law: total pressure exerted by gas mixtures is equal to the sum of partial pressures all the component gases
The pressure exerted by an individual gas in a mixture of known gases
Expressed in terms of its dry gas concentration
What is fractional concentration?
The percentage or concentration of a gas in a mixture of gases
Why is partial pressure of water vapor taken into consideration when calculating partial pressure in trachea?
Air is humidified in the conducting zone therefore, the partial pressure of water vapor (Ph2o) must be taken into consideration
Inspired Ph2o is not altered by altitude
What is Henry’s law and partial pressure?
- in venous blood the drop in PO2 is greater than the rise in PCO2
- Water vapor pressure depends on temperature, at 37 degrees Celsius max 47 mm Hg
How does air composition of air change with altitude?
With increasing altitude the composition of air remains the same but the barometric pressure decreases
Mount Everest is 8848 m high
The barometric is 253 mm Hg
PO2- 53 mm Hg
The fractional concentration of oxygen doesn’t change but, the PO2 decreases
What is minute ventilation?
Volume of air moved in or out lungs per unit time
Minute ventilate= total ventilation
Ve= Vt x f
Vt= tidal volume- typically~500 ml
f- breathing frequency -vtypically 12/min
Therefore minute ventilation= (0.5 liters)x12/min= 6 liters per minute
Air is distributed into two compartments…
- Dead space (VD) in which gas exchange cannot occur
- Alveolar space where there is gas exchange
Wasted air: air that does participates in gas exchange
What is dead space( Vd)
Volume 0f inhaled air that does not participate in gas exchange
Regions of no gas exchange include:
- Conducting airways: an atomic dead space
- Alveoli with no perfusion - alveolar dead space
Physiological dead space= anatomical dead space+ alveolar dead space
What is pulmonary embolism?
Emboli is lodged in a branch of the pulmonary artery
- Inadequate pulmonary blood flow (poor perfusion)
- Inadequate perfusion leads to inadequate exchange of gas (ventilation in excess of perfusion)
- Increased I; the physiological dead space
What is alveolar ventilation?
Volume of air delivered to the respiratory zone per minute
- The fraction of inspired air that participates in gas exchange
- Alveolar ventilation is dependent on depth of breathing (tidal volume) and rate of breathing(frequency)
- Increasing the depth of breathing is far more effective in elevating alveolar ventilation than is increasing the frequency or rate of breathing
How gas partial pressures and ventilation related?
Alveolar ventilation is usually evaluated in terms of arterial PCO2
- Increased alveolar ventilation beyond that required to meet metabolic needs is termed hyperventilation
- Hyperventillation leads to hypocapia (PaCO2 is below normal)
- Decreased alveolar ventilation below that required to meet metabolic needs is termed hypoventilation
- Hypoventilation leads to decrease in PaO2 and hypercapnia (e”levated in PaCO2)
What are the factors determining alveolar oxygen partial pressure( PAO2)?
Altitude- the fractional concentration of oxygen doesn’t change but, the PO2 decreases with an increase in altitude
Supplemental oxygen- providing a high PO2 increases PAO2
Metabolic activity- high metabolic activity uses oxygen and would push PAO2 down
Ventilation- increasing ventilation keeps PAO2 elevated
What are the factors affecting PACO2?
PACO2- alveolar partial pressure of CO2
PaCO2- arterial partial pressure of carbon dioxide
Carbon dioxide is a highly diffusable gas, alveolar PCO2 is assumed to be equal to arterial PCO2
-In the steady state, carbon dioxide excreted by the lungs equals that produced from metabolism
Therefore, PACO2 is inversely proportional to alveolar ventilation (PaCO2 is also inversely proportional to alveolar ventilation/VA)
What is hypocentilation?
Decreased alveolar ventilation with increased PaCO2
What is hyperventilation?
Increased alveolar ventilation with decreased PaCO2
What is hypercapnia?
Increased carbon dioxide in blood
What is Eupnia?
Normal breathing
What is hypopnea?
Decreased ventilation in response to lowered metabolic CO2 production
What is hyperpnea?
Increased ventilation in response to increased metabolic CO2 production
What is tachypnea?
Increased frequency of breathing. Ventilation may or may not change depending on tidal volume
What is Dyspnea?
Shortness of breath/ labored breathing (ill breathing)
What is apnea ?
‘A’ prefix= without
Temporary cessation of breathing
