PILBEAMS CHAPTER 1 QUESTIONS WITH
COMPLETE SOLUTIONS
Compliance Measurement
to describe the elastic forces that oppose lung inflation
C = V/P
compliance (L/cm H2O)
P = V/C
pressure (cm H2O)
V=CxP
Volume (L or mL)
1. posture
2. position
3. actively inhaling or exhaling
Compliance vary on person’s:
0.05 - 0.17 L/cmH2O or 50-70 mL/cmH2O
Normal Compliance
40-50 mL/H2O upto 100 mL/H2O
Normal compliance in Male intubated patients
35-45 mL/H2O upto 100 mL/H2O
Normal compliance in Female intubation patients
,ARDS
Kyphoscoliosis
Diseases that cause reduce compliance or increases thoracic
pressure:
Emphysema
Disease that causes increase compliance:
Static Compliance or Static Effective Compliance
patients receiving MV, compliance is measured during no flow
conditions (plateau pressure)
Cs = VT / (Pplateau - PEEP)
Calculating Static Compliance (L/cmH2O):
baseline pressure
EEP =
RESISTANCE
frictional forces that must be overcome during breathing
airway structure + tissue viscous resistance
frictional forces =
1. gas viscosity
2. gas density
3. length and diameter of the tube
4. flow rate of the gas though the tube
Resistance to airflow through conductive airways depends
on:
, 1. bronchospasm
2. increased secretions
3. mucosal edema
4. kink in the ET tube
Conditions decreasing airway lumen and gas flow:
Viscous Resistance
layers of gas flow over each other = resistance to flow
Raw = (PIP - Pplateau) / flow
Calculation of Airway Resistance (cm H2O/ [L/s]):
0.6-2.4 cm H2O/ [L/s] at 0.5 L/s flow
Normal resistance value
6 cm H2O/ [L/s] or higher
Normal resistance value for intubated patients:
5-7 cm H2O/ [L/s]
increase of airway resistance when ET tube size decreases
13-18 cm H2O/ [L/s]
Resistance value of unintubated patient with emphysema or
asthma:
Greater resistance
- decrease pressure in conducting airways
- less pressure to expand alveoli
- more force to maintain gas flow
TIME CONSTANTS
COMPLETE SOLUTIONS
Compliance Measurement
to describe the elastic forces that oppose lung inflation
C = V/P
compliance (L/cm H2O)
P = V/C
pressure (cm H2O)
V=CxP
Volume (L or mL)
1. posture
2. position
3. actively inhaling or exhaling
Compliance vary on person’s:
0.05 - 0.17 L/cmH2O or 50-70 mL/cmH2O
Normal Compliance
40-50 mL/H2O upto 100 mL/H2O
Normal compliance in Male intubated patients
35-45 mL/H2O upto 100 mL/H2O
Normal compliance in Female intubation patients
,ARDS
Kyphoscoliosis
Diseases that cause reduce compliance or increases thoracic
pressure:
Emphysema
Disease that causes increase compliance:
Static Compliance or Static Effective Compliance
patients receiving MV, compliance is measured during no flow
conditions (plateau pressure)
Cs = VT / (Pplateau - PEEP)
Calculating Static Compliance (L/cmH2O):
baseline pressure
EEP =
RESISTANCE
frictional forces that must be overcome during breathing
airway structure + tissue viscous resistance
frictional forces =
1. gas viscosity
2. gas density
3. length and diameter of the tube
4. flow rate of the gas though the tube
Resistance to airflow through conductive airways depends
on:
, 1. bronchospasm
2. increased secretions
3. mucosal edema
4. kink in the ET tube
Conditions decreasing airway lumen and gas flow:
Viscous Resistance
layers of gas flow over each other = resistance to flow
Raw = (PIP - Pplateau) / flow
Calculation of Airway Resistance (cm H2O/ [L/s]):
0.6-2.4 cm H2O/ [L/s] at 0.5 L/s flow
Normal resistance value
6 cm H2O/ [L/s] or higher
Normal resistance value for intubated patients:
5-7 cm H2O/ [L/s]
increase of airway resistance when ET tube size decreases
13-18 cm H2O/ [L/s]
Resistance value of unintubated patient with emphysema or
asthma:
Greater resistance
- decrease pressure in conducting airways
- less pressure to expand alveoli
- more force to maintain gas flow
TIME CONSTANTS
