Ventilator Graphics Quiz
Questions: 16 · 10 minutes
1. During ventilation, the pressure waveform abruptly collapses and measured exhaled tidal volume falls markedly. Which event should be considered immediately?
A gradual improvement in respiratory-system compliance
A circuit disconnection or major airway-system leak
An isolated increase in inspiratory flow demand
A successful recruitment maneuver
2. During volume-controlled ventilation, the pressure-time waveform becomes concave or scooped during inspiration while the patient appears to demand more flow. What is the most likely interpretation?
The expiratory time is excessively long
Lung compliance has necessarily improved
The circuit is definitely disconnected
Available inspiratory flow may be insufficient for patient demand
3. Why is plateau pressure measured during an inspiratory hold when flow is approximately zero?
It measures the highest pressure generated by airway resistance
It reduces the resistive pressure component and better approximates alveolar pressure
It calculates intrinsic PEEP during active exhalation
It guarantees that all lung units have identical pressure
4. A volume-time scalar rises during inspiration but does not return to its prior baseline after expiration. Which issue should be considered first?
An excessive inspiratory flow setting
An inspiratory pause that is too long
A leak in the patient-airway or ventilator circuit system
A respiratory rate that is below the set value
5. The upper portion of a pressure-volume loop flattens and develops a beak-like appearance as pressure continues to rise. What does this suggest?
Possible overdistention at higher pressures or volumes
A leak that occurs only during expiration
Insufficient expiratory flow measurement
Improving compliance throughout inspiration
6. Small, repeated sawtooth-like oscillations appear on pressure and flow waveforms. What is the most appropriate initial interpretation?
They prove that lung compliance has suddenly improved
They confirm overdistention at end inspiration
They show that every breath is fully patient-triggered
Secretions, condensate, or another source of turbulent flow may be present and should be assessed
7. Which ventilator delivery pattern most directly creates a rectangular, constant inspiratory flow waveform?
A preset constant inspiratory flow
A decelerating pressure-targeted breath
An expiratory hold maneuver
An unsupported spontaneous breath
8. On the flow-time scalar, expiratory flow remains below zero when the next inspiration begins. What does this pattern indicate?
Complete exhalation with adequate expiratory time
A leak limited to the inspiratory phase
Incomplete exhalation with possible intrinsic PEEP
A successful inspiratory hold maneuver
9. Both peak inspiratory pressure and plateau pressure rise by similar amounts while tidal volume is unchanged. Which problem is most consistent with this pattern?
An isolated increase in endotracheal-tube resistance
A pure expiratory circuit leak
Reduced respiratory-system compliance
A lower-than-set respiratory rate
10. On a standard pressure-time scalar, what do the horizontal and vertical axes represent?
Time horizontally and airway pressure vertically
Airway pressure horizontally and volume vertically
Volume horizontally and flow vertically
Flow horizontally and airway pressure vertically
11. A flow-time scalar shows that exhalation is still occurring when each new mandatory breath begins. Which adjustment would most directly provide more time for exhalation?
Reduce respiratory rate or shorten inspiratory time, as clinically appropriate
Lengthen inspiratory time
Increase the respiratory rate while leaving other settings unchanged
Add a longer inspiratory pause
12. A patient is receiving pressure-controlled ventilation. The set inspiratory pressure is unchanged, but respiratory-system compliance worsens. What change is most likely?
Tidal volume rises while pressure remains constant
Delivered tidal volume decreases
Tidal volume remains fixed because pressure is fixed
Peak pressure falls below the set inspiratory pressure
13. A flow-volume loop has a distinctly scooped expiratory limb compared with the expected contour. Which mechanical pattern does this most strongly suggest?
Improved inspiratory compliance
Expiratory airflow obstruction or flow limitation
A prolonged inspiratory hold
An isolated failure to trigger inspiration
14. On a conventionally displayed flow-volume loop, which variable is plotted on the vertical axis?
Airway pressure
Time
Flow
Respiratory rate
15. What does a lower inflection point on the inspiratory limb of a pressure-volume loop most commonly represent?
The onset of upper-lung overdistention
The pressure at which expiratory flow reaches zero
The difference between peak and plateau pressure
A pressure range where substantial alveolar recruitment begins
16. Peak inspiratory pressure rises, but plateau pressure and delivered tidal volume remain nearly unchanged. Which change best explains this pattern?
Decreased set PEEP
Reduced respiratory-system compliance
Increased alveolar recruitment
Increased airway resistance