Mechanics Of Ventilation Flashcards
Why does the absence of surfactant lead to pulmonary edema
The alveoli begin to collapse due to an inward increase in tension. This creates a vacuum that sucks in blood from the capillary
Do the small or large areas have the least resistance
Small
Obstructive diseases affect the _______ airways
Small
Helium is frequently added (in place of some N2 gas) water divers’ tanks because
Helium is less viscous than N2 and reduces therefore the main airway resistance
How come breathing helium is not beneficial in asthma
It does not reduce resistance in small airways
Forced expiration causes airway constriction and ______ airway resistance
Increase
You are in inspiration is the transairway pressure is ___________
Positive
The point in the airways where Paw = Ppl
Equal point pressure
Airway proximal to EPP can collapse during _____ _________
Forced expiration
Which of the following plays a role in the occurrence of expiratory wheezes in patients with COPD with emphysematous changes
Reduced elastic recoil
The difference in work for inspiration and expiration is called
Hysteresis
Does it cause more work to inflate or deflate the lung
Inflate
What does FEV represent
The amount of air that can be pushed out in one second
What is a normal FEV/FVC ratio
75-85%
What do you suspect if a patients FEV/FVC is 40%
Obstructive pulmonary disease
What do you suspect if a patents vital capacity is low
Restrictive lung disease
If a low flow is seen on FEF what is suspected
Obstruction
If low volume is seen on FEF what is suspected
Restriction
collapse of the airways is more likely to occur in forced _________
Expiration (seen in COPD patients)
A space where no exchange happens
Dead space
What is the equation of alveolar ventilation
Respiratory frequency x (tidal volume-dead space)
The amount of air reaching the alveoli over minute
Alveolar ventilation
At 30/min, Vt of 9L/min (compared to normal breathing 7.5 L/min, RR14/min) you expect his arterial Co2 (PaCO2) to
Increase above normal
VT =9000 mL/min / 30 RR = 300 tidal volume
Normal = 500
Hyperpnea
This is shallow air/breathing
What is the equation for calculating total dead space volume
VD= VT- (Peco2 x VT/ Paco2
