Chapt 1 & 2 (RTH 162) Flashcards
What is the most common cause of increased airway resistance?
COPD. (Chronic obstructive pulmonary disease like emphysema chronic bronchitis chronic asthma and bronchiectasis)
What is one of the most frequent use of mechanical ventilation?
Management of postoperative patients recovering from anesthesia and medications.
Explain the Poiseuille’s law:
The work of breathing increases by a factor of 16 fold when the radius of the airway is reduced by half its original size.
What is the normal airway resistance in healthy adults?
Between 0.5 and 2.5 cm H2O/liter/second
Airway resistance :
Airway resistance varies directly with the length and inversely with the diameter of the airway or ET tube.
What is the equation of airway resistance, how is it calculated?
Pressure change / flow
Airway resistance and flow in the equation are inversely related.
What is the equation for pressure change?
Peak inspiratory pressure - plateau pressure.
When does ventilatory failure occur?
When the patients minute ventilation cannot keep up with CO2 production.
In the pressure/volume loop what does an increase bowing of the pressure/volume loop suggest?
And overall increase in airflow resistance.
What is lung compliance?
Volume change (lung expansion) per unit pressure change (work of breathing)
C= volume change / pressure change
What is the equation for static compliance?
Corrected tidal volume / (plateau pressure - peep)
What is the equation for dynamic compliance?
Corrected tidal volume / (peak inspiratory pressure - Peep)
What is a normal static compliance?
40 to 60 cm H2O
What is normal dynamic compliance?
30 to 40 cm H2O
In the pressure to volume slope what does a shift of the slope towards the pressure axis indicate?
A decrease in compliance.
In the pressure to volume slope what does a shift towards the volume axis indicate
An increase in compliance.