Mechanics of ventilation Flashcards
volume of air in a container is inversely proportional to the pressure within that container
Boyle’s Law
an increase in pressure (more positive) will
decrease the volume of gas
a decrease in pressure (more negative) will
increase the volume of gas
What muscles work during Inhalation
- sternocleidomastoid muscles-lift sternum up
- Scalene muscles-elevates ribs 1 & 2
- Pectoralis minor muscles- elevate ribs 3 to 5
What muscles work during Exhalation
- Abdominal muscles
- Internal Intercostal muscles
the ease with which the lungs or chest wall expand
Compliance
the ease of airflow down through the tubes
Airway Resistance
two conditions that may require the use of accessory muscles to generate a greater force to fill & empty the lungs & higher airway resistance & poor compliance
Compliance & Airway Resistance
air in the pleural space causing collapse of the lungs
Pneumothorax
blood in the pleural space causing collapse of the lungs
Hemothorax
air & blood in pleural space
Hemopneumothorax
amount of air moved in 1 minute
minute ventilation
minute ventilation equation=
tidal volume(VT) x ventilation rate
Average tidal volume=
500mL x 12/min = 6,000mL
amount of air moved in & out of the alveoli in 1 minute
Alveolar Ventilation
no gas exchange occurs in what space?
Dead space
used when extra effort is needed for inhalation or exhalation
Accessory muscles
the ease of airflow into & out of the airway structures
Resistance
Negative pressure is maintained in the
Pleural space
Air that does not reach the alveoli, remaining in the trachea & bronchi, is called?
dead space air
Alveolar ventilation=
(tidal volume-dead air space) x frequency of ventilation/minute
Hypoxia can occur from:
- a low tidal volume
- a slow ventilator rate
- a fast ventilator rate
When the ventilator rate is too fast:
there is inadequate time between breaths to fill the lungs
Ventilatory rates of ___ per min. or greater in ADULTS are too fast to allow adequate time for normal tidal volume
40
Ventilatory rates of ___ per min. or greater in a PEDIATRIC are too fast to allow adequate time for normal tidal volume
60
