Lung Volumes Flashcards
what is Functional Residual Capacity?
FRC = the amount of air left in the chest after normal expiration
what 2 volume make up functional residual capacity?
residual volume + expiratory reserve volume
what determines FRC?
the balance of the inwards and outwards pull on the thoracic cage/lungs
what causes a decrease in FRC?
Increased inward pull (atelectasis/fibrosis)
AND
Decreased outward pull (obesity/ spinal and thoracic deformity)
what are the consequences of reduced FRC?
Problems with
- gas exchange
- ventilation perfusion (V/Q) matching
what is Tidal Volume?
TV = the amount of air inhaled and exhaled during a normal breath
what is the normal TV for a healthy adult?
500 mL
what causes loss of TV?
- Decreased lung and chest compliance
- Weak respiratory muscles
- Increased airway resistance
what are the consequences of a reduced TV?
- Hypoventilation
- CO2 retention
- Acidosis
- Hypoxia
name some treatments for reduced TV
Thoracic Expansion Exercises
Intermittent Positive Pressure Breathing
Incentive spirormetry
NIV
What is forced vital capacity?
FVC = the amount of air a person can forcefully exhale after taking their deepest breath possible
what causes decreased FVC?
- Impaired inspiratory capacity
- Impaired exspiratory capacity
describe the consequences of decreased FVC
- FVC <1 = ineffective cough
- Retained secretions
- Decreased O2
- CO2 retention
list some treatments for reduced FVC
- IPPB
- NIV
- Breath stacking / SNIFF
- Thoracic mobility
- Positioning
- Breathing exercises
what is expiratory reserve volume?
ERV = the additional amount of air that can be exhaled forcefully after normal TV
what is inspiratory reserve volume?
IRV = the additional amount of air that can be inhaled forcefully after normal TV
what is residual volume?
the amount of air remaining in the lungs after maximal exhale, which cannot be expelled
why is residual volume important?
it helps to keep the alveoli open and prevents lungs from collpasing
what is V/Q matching?
= the relationship between ventilation (V) and perfusion (Q) in the lungs.
Ventilation is the process of air moving in and out of the lungs, while perfusion is the flow of blood through the pulmonary capillaries to exchange gases.
what are the signs/ symptoms of volume loss
- decreased air entry on auscultation
- increased RR
- altered ABG’s
- decreased TV
what are the main things we see in ABG’s?
pH
SpO2
SpCO2
HCO3
Be
H+
what are the normal values for ABG’s?
pH =7.35-7.45
SpO2 = 11.3-13.3
SpCO2 = 4.7-6
HCO3 = 22-26
Be = -2 +2
H+ = 35-45
how would you tell the difference between respiratory and metabolic issues?
if PaCO2 is off = Respiratory
if HCO3 is off = metabolic
how would you tell the difference between respiratory and metabolic issues? (*both values are off)
if pH moves OPPOSITE to CO2 = resp.
if pH moves SAME to CO2 = metabolic
