At which point in the pressure-time curve of a spontaneous breath ...

[joe]

At which point in the pressure-time curve of a spontaneous breath should the transdiaphragmatic pressure be greatest?
 
  a. Mid-inspiration
  b. Mid-expiration
  c. End of exhalation
  d. Beginning of inspiration

Question 2

Calculate the airway resistance given the following clinical data: flow rate 60 L/min, peak inspir-atory pressure (PIP) 42 cm H2O, plateau pressure (Pplateau) 15 cm H2O, and positive end-expiratory pressure (PEEP) 5 cm H2O.
 
  a. 10 cm H2O/L/sec
  b. 30 cm H2O/L/sec
  c. 37 cm H2O/L/sec
  d. 42 cm H2O/L/sec

[reversalruiz]

Answer to Question 1

ANS: A
The transdiaphragmatic pressure is the difference between the gastric and esophageal pressures, as measured during the respiratory cycle. The greatest distance between these two pressures dur-ing the respiratory cycle is at the middle of inspiration, when the esophageal pressure is at its lowest point. At mid-expiration the gastric and esophageal pressure difference is at its smallest point. See Figure 10-25.

Answer to Question 2

ANS: B
60 L/min = 1 L/sec. Raw = (PIP  Pplateau)/(L/sec) = (42  15)/1 = 30 cm H2O/L/sec.

[joe]

Thank you

[reversalruiz]

No problemo