Pressure-Controlled Ventilation: Mode of Ventilation (2025)

Pressure-controlled ventilation is a commonly used mode in mechanical ventilation, especially in critically ill patients with compromised lung compliance. Unlike volume-controlled modes that guarantee a set tidal volume, pressure-controlled ventilation focuses on limiting airway pressure to reduce the risk of ventilator-induced lung injury.

In this article, we’ll explore how pressure-controlled ventilation works, when it’s used, its advantages and limitations, and what healthcare professionals must monitor to ensure safe and effective support.

What Is Pressure-Controlled Ventilation?

Pressure-controlled ventilation is a mode in which the ventilator delivers air until a preset pressure is reached, rather than delivering a fixed volume. The clinician sets the inspiratory pressure, respiratory rate, inspiratory time, and other parameters, and the ventilator delivers a breath that continues until the target pressure is achieved and maintained for the duration of inspiration.

In this mode, tidal volume is not guaranteed—it varies depending on the patient’s lung compliance, airway resistance, and effort. The primary goal is to minimize the risk of barotrauma by capping airway pressures, which is particularly important in patients with stiff or injured lungs.

How It Works

The key settings in pressure-controlled ventilation include:

• Inspiratory Pressure: The maximum pressure delivered during inspiration
• Inspiratory Time (Ti): The duration of the inspiratory phase
• Respiratory Rate (RR): Number of breaths per minute
• PEEP and FiO₂: Settings for oxygenation support

The ventilator delivers flow rapidly at the beginning of inspiration to reach the set pressure, then maintains that pressure until the inspiratory time ends. Expiration is passive.

Because tidal volume depends on the lung’s ability to expand under that pressure, close monitoring of exhaled tidal volume is essential.

Clinical Applications

Pressure-controlled ventilation is often used in:

• Patients with acute respiratory distress syndrome (ARDS)
• Patients with low lung compliance or high airway resistance
• Neonates and pediatric patients
• Lung-protective strategies to avoid high airway pressures
• Patients at risk for barotrauma or volutrauma

Note: This mode is also preferred when controlling pressures is more important than achieving a specific tidal volume.

Advantages of Pressure-Controlled Ventilation

• Limits Peak Airway Pressure: Reduces the risk of barotrauma
• Improved Distribution of Ventilation: May benefit patients with heterogeneous lung disease
• Customizable Inspiratory Time: Allows for prolonged time at pressure for improved gas exchange
• Useful for Lung-Protective Ventilation: Especially in ARDS or patients with fragile lungs

Limitations and Considerations

Because the ventilator does not guarantee a set tidal volume, hypoventilation can occur if compliance worsens or resistance increases. Some key limitations include:

 

• Variable Tidal Volume: Makes consistent minute ventilation harder to achieve
• Requires Frequent Monitoring: Clinicians must monitor exhaled tidal volume and adjust pressure as needed
• Not Ideal for All Patients: For those needing strict control of carbon dioxide, volume control may be more appropriate
• Risk of Hypoventilation: In cases of sudden compliance loss (e.g., pneumothorax, worsening edema), delivered volume may drop

Modes That Use Pressure-Controlled Ventilation

• Assist/Control (A/C) Pressure Control: Every breath, whether machine-triggered or patient-triggered, is delivered to the set inspiratory pressure, which provides full support.
• Synchronized Intermittent Mandatory Ventilation (SIMV) with Pressure Control: Mandatory breaths are pressure-controlled, while spontaneous breaths may be supported with pressure support.
• Pressure Support Ventilation (PSV): Spontaneous breaths are assisted by a set pressure above PEEP. Though not a full pressure control mode, it uses the same pressure-limited principle.

Patient-Ventilator Synchrony

Patient comfort and synchrony can be optimized in pressure-controlled ventilation, especially when inspiratory time and trigger sensitivity are properly adjusted. Benefits include:

• Reduced work of breathing
• Better tolerance during weaning
• Improved oxygenation with prolonged inspiratory times

Note: If the patient’s own respiratory pattern conflicts with the ventilator’s timing, discomfort or dyssynchrony may occur, requiring adjustments to settings or sedation.

Monitoring and Reassessment

Since tidal volume is variable, clinicians must regularly evaluate:

• Exhaled Tidal Volume (VTe)
• Lung compliance and airway resistance
• Blood gases (especially CO₂ levels)
• Oxygenation and respiratory effort

Note: If the delivered volume becomes inadequate, increasing the inspiratory pressure or switching to a volume-controlled mode may be necessary. The patient’s condition, comfort, and ventilation goals should guide ongoing adjustments.

Pressure-Controlled Ventilation vs. Volume-Controlled Ventilation

While both pressure-controlled and volume-controlled ventilation are foundational modes in mechanical ventilation, they operate using fundamentally different principles and are selected based on the specific needs of the patient:

Pressure-Controlled Ventilation

In pressure-controlled ventilation, the clinician sets the inspiratory pressure and inspiratory time, and the tidal volume delivered depends on the patient’s lung compliance and airway resistance. This mode is often preferred in patients with conditions such as acute respiratory distress syndrome (ARDS), where protecting the lungs from high pressures is a top priority.

The primary advantage is that peak airway pressure is limited, thereby reducing the risk of barotrauma and volutrauma. However, the variable nature of tidal volume can make it more difficult to ensure consistent minute ventilation, and careful monitoring is required to prevent hypoventilation.

Volume-Controlled Ventilation

In contrast, volume-controlled ventilation guarantees a specific tidal volume with each breath, regardless of the pressure needed to deliver it. This mode is useful when precise control of carbon dioxide elimination is essential, such as in patients with metabolic acidosis or brain injuries.

However, because the ventilator increases pressure to meet the volume target, it can result in dangerously high airway pressures if lung compliance decreases, thereby putting the patient at risk for ventilator-induced lung injury.

The decision between these two modes involves weighing the importance of pressure limitation versus volume assurance. Patients with stiff, non-compliant lungs often benefit from pressure control, while those needing strict ventilation targets may require volume control.

Note: Clinicians must continuously assess the patient’s condition, response to therapy, and ventilator pressures to determine which mode is safest and most effective at any given time.

Pressure-Controlled Ventilation Practice Questions

1. What are common indications for pressure-controlled ventilation (PCV)?  
Increased peak inspiratory pressures (PIP), poor lung compliance (plateau >35 cmH2O), lung injury or surgery, persistent circuit leaks, and severe oxygenation issues.

2. What is a major disadvantage of pressure-controlled ventilation?  
Tidal volume delivery varies with changes in compliance and resistance, making ventilation less predictable.

3. How is tidal volume determined in pressure-controlled ventilation?  
It depends on patient effort and lung mechanics; it may be reduced if the inspiratory time (Ti) is too short.

4. How is pressure determined in pressure-controlled ventilation?  
The clinician sets the target pressure level for each breath.

5. What is the typical flow rate range provided by the ventilator in PCV?  
Usually between 70–100 L/min, but some ventilators can deliver up to 180 L/min.

6. What type of flow waveform is seen in pressure-controlled ventilation?  
A decelerating flow waveform.

7. True or False: In PCV, the patient can exceed the machine’s set flow rate.  
True — flow delivery varies based on demand.

8. How does PCV create an inspiratory pause?  
Flow decreases to zero while pressure continues for the remainder of Ti, resulting in an inspiratory hold.

9. What is the benefit of an inspiratory pause in PCV?  
It increases mean airway pressure (MAP) and promotes alveolar recruitment for better oxygenation.

10. How is pressure-controlled ventilation triggered?  
It can be triggered by time, patient effort, or manual initiation.

11. What is the cycle variable in pressure-controlled ventilation?  
Time — the breath ends once the set inspiratory time has elapsed.

12. What ventilator modes can use pressure-controlled ventilation?  
PCV can be used in CMV (controlled mandatory ventilation) and SIMV (synchronized intermittent mandatory ventilation).

13. Which of the following settings is specific to pressure-controlled ventilation?  
I-Time — it is set to enhance comfort and oxygenation.

14. True or False: PC and VC modes are available in spontaneous ventilation.  
False — PC and VC apply to control modes, not spontaneous modes.

15. PC can be used to help maintain an appropriate ____________ to prevent barotrauma.  
Peak Pressure — limiting peak pressure reduces the risk of pressure-related lung injury.

16. True or False: Pulmonary pathology plays no role in choosing between PC and VC.  
False — lung pathology strongly influences mode selection.

17. What is the main difference between CMV and SIMV in PCV mode?  
CMV delivers a full set breath with every trigger, including patient effort. SIMV allows patient-triggered spontaneous breaths without stacking.

18. If a pressure-control ventilator cycles into exhalation before flow reaches zero, what does this suggest?  
Inspiratory time is too short, and the lungs were still filling.

19. How can early exhalation in pressure-controlled ventilation be corrected?
By increasing the inspiratory time (Ti).

20. What happens when pressure is maintained throughout the entire inspiratory time?  
Tidal volume delivery increases as the lungs have more time to fill.

21. True or False: Rise time can be used in pressure-controlled ventilation.  
True — it adjusts how quickly the set pressure is reached.

22. What is rise time in mechanical ventilation?  
It is the time taken to reach the set inspiratory pressure after a breath begins.

23. What may occur if rise time is set too fast?  
Pressure builds too quickly, possibly causing early cycling or discomfort.

24. What may occur if rise time is set too slow?  
The patient may become air hungry, increasing the work of breathing.

25. How should pressure-controlled ventilation be initially set up?  
Start with inspiratory pressure 10–15 cmH2O above baseline, aiming for previous plateau pressures, and adjust to achieve target tidal volume.

26. In pressure-controlled ventilation, what key settings are typically adjusted by the clinician?  
Respiratory rate (RR), inspiratory time (Ti), pressure level, FiO₂, and PEEP.

27. What does a typical physician’s order for pressure control ventilation look like?  
Mode/Pressure/Ti/FiO₂/PEEP (e.g., CMV-PC/30/1/.40/+10).

28. What happens to tidal volume in pressure-controlled ventilation if lung compliance increases?
Tidal volume increases.

29. What happens to tidal volume in pressure control if air trapping or auto-PEEP develops?  
Tidal volume decreases.

30. True or False: Pressure-controlled ventilation does not lead to permissive hypercapnia.  
False; permissive hypercapnia can occur due to limited control over tidal volume.

31. Can the inspiratory time (Ti) be changed in PCV without a physician’s order?  
No, because changing Ti affects tidal volume and mean airway pressure (MAP), impacting oxygenation.

32. Can pressure support (PS) be used with PC-SIMV mode?  
Yes, PS can be added to assist spontaneous breaths in PC-SIMV.

33. In pressure control ventilation, what happens to tidal volume during air trapping?  
Tidal volume decreases due to reduced effective inspiratory time and lung filling.

34. Can you set the flow rate manually in pressure-controlled ventilation?  
No, the flow is variable and determined by patient demand and system pressure.

35. What type of flow waveform is associated with pressure-controlled ventilation?  
A decelerating flow pattern.

36. Can a patient draw in more flow than the ventilator delivers in PCV?  
Yes, the patient can exceed the machine-delivered flow if needed.

37. What are some causes of decreased tidal volume in PCV?  
Endotracheal tube kinking, obstruction, or water accumulation in the circuit tubing.

38. What is considered a safe peak inspiratory pressure (PIP) in pressure-controlled ventilation?  
A PIP ≤ 45–50 cm H₂O is considered safe.

39. What is the recommended maximum plateau pressure in PCV to avoid lung injury?  
<35 cm H₂O.

40. What is the target maximum mean airway pressure (MAP) to reduce the risk of barotrauma?  
<30 cm H₂O.

41. What is considered a safe PEEP setting to avoid overdistension in PCV?  
PEEP <10 cm H₂O.

42. How can you decrease PaCO₂ in pressure-controlled ventilation?  
Increase pressure (delta P), increase RR, or extend Ti if the flow waveform doesn’t reach baseline.

43. How can you increase PaCO₂ in pressure-controlled ventilation?  
Decrease the pressure or reduce the respiratory rate.

44. How do you reduce PaO₂ in pressure-controlled ventilation?  
Lower the FiO₂ or decrease the delta pressure (pressure control level).

45. How can you increase PaO₂ in pressure-controlled ventilation?  
Increase FiO₂, lengthen inspiratory time (Ti), or use inverse ratio ventilation (IRV).

46. What is pressure-controlled ventilation commonly used to manage?  
ARDS, pneumothorax, atelectasis, and interstitial lung disease (ILD).

47. Why is the decelerating flow waveform beneficial in PCV?  
It allows for better gas distribution and improved oxygenation.

48. What type of flow pattern is most common and delivers the shortest Ti?  
Rectangular (square) flow pattern.

49. What flow pattern is used in pressure-controlled ventilation?  
Descending ramp waveform.

50. Why can resistance (Raw) not be calculated in PCV with descending ramp flow?  
Because the flow is variable and not constant, making Raw calculations inaccurate.

51. What are some advantages of pressure-controlled ventilation?  
It provides on-demand flow, reduces peak pressures, improves oxygenation, and limits overdistension.

52. How does pressure-controlled ventilation support lung healing?  
By reducing barotrauma and volutrauma through pressure limits and improved oxygenation.

53. What impact does pressure-controlled ventilation have on work of breathing and sedation needs?  
It reduces work of breathing (WOB), sedation requirements, and ventilator duration.

54. How does increasing inspiratory time affect mean airway pressure (MAP)?
It increases MAP, which can enhance oxygenation.

55. True or False: The patient cannot trigger additional breaths in pressure-controlled ventilation.
False; the patient may breathe above the set rate, especially in spontaneous or assisted modes.

56. What is one major disadvantage of pressure control ventilation?  
Initial high flow can cause shear trauma to the alveoli, and tidal volume varies with changes in lung compliance or resistance.

57. What is the formula for calculating mean airway pressure (MAP)?  
MAP = ½ (PIP – PEEP) × (Ti/TCT) + PEEP

58. In pressure control ventilation, which variable is considered variable?  
Tidal volume (VT) is variable.

59. In pressure control ventilation, which variable is considered constant?  
Peak inspiratory pressure (PIP) remains constant.

60. In pressure control ventilation, what determines the tidal volume delivered?  
Lung compliance and airway resistance.

61. What ventilation mode can pressure control be used with?  
It can be used as either CMV (Continuous Mandatory Ventilation) or SIMV (Synchronized Intermittent Mandatory Ventilation).

62. In pressure control ventilation, what happens to PIP and VT?  
PIP is fixed, while VT varies depending on impedance.

63. In which ventilation mode are mandatory breaths pressure-controlled and spontaneous breaths pressure-supported?  
SIMV with pressure support.

64. How is the flow pattern determined in pressure control ventilation?  
Flow is patient-demand driven and influenced by airway resistance, lung compliance, and inspiratory time.

65. What is PC-CMV (aka PCV) commonly used for?  
To reduce shear forces in the lungs when peak or plateau pressures exceed 35 cm H₂O and when permissive hypercapnia is desired.

66. How do shear forces damage the alveoli during mechanical ventilation?  
By repeated alveolar collapse and reopening, leading to structural damage over time.

67. What ventilation strategy is often used in the management of ARDS to minimize lung injury?  
Permissive hypercapnia.

68. What is permissive hypercapnia?  
A strategy allowing PaCO₂ to rise intentionally to reduce ventilator pressures and minimize barotrauma.

69. How is a gradual rise in PaCO₂ achieved in permissive hypercapnia?  
By reducing tidal volume through lower pressure settings without significantly impacting oxygenation.

70. What does PC-IRV (Pressure-Controlled Inverse Ratio Ventilation) involve?
An I:E ratio greater than 1:1 to prolong inspiratory time.

71. What are some physiological effects of PC-IRV?  
It increases mean airway pressure and may lead to intrinsic PEEP (auto-PEEP).

72. On which patients is PC-IRV typically used?  
Those with severe hypoxemia unresponsive to high FiO₂ and PEEP.

73. What does intrinsic PEEP in PC-IRV help accomplish?  
Alveolar recruitment and improved oxygenation.

74. What cardiovascular effect can result from increased mean intrathoracic pressure during PC-IRV?  
Decreased cardiac output, potentially reducing overall oxygen delivery.

75. Why must most patients on PC-IRV be sedated and paralyzed?  
Because it’s not a natural breathing pattern, requiring drugs like Diprivan or Norcuron for compliance.

76. What is the formula for calculating total oxygen content (CaO₂)?  
CaO₂ = (PaO₂ × 0.003) + (Hb × 1.34 × SaO₂)

77. What ventilation mode is similar to PC-IRV but allows for spontaneous breathing?  
APRV (Airway Pressure Release Ventilation).

78. How does APRV function during ventilation?  
It alternates between high (IPAP) and low (EPAP) pressures to facilitate gas exchange.

79. How long does the airway pressure release phase last in APRV?  
Usually 1.5 seconds or less to allow passive exhalation and CO₂ removal.

80. How does the I:E ratio in APRV differ from that in PC-IRV?  
Both have I:E ratios >1:1, but APRV permits spontaneous breathing throughout.

81. Why is less sedation typically needed with APRV?  
Because the patient can breathe spontaneously, leading to greater comfort and reduced sedation needs.

82. What type of airway pressure is usually lower in APRV compared to conventional modes?  
Peak airway pressure.

83. What condition was APRV originally developed to treat?  
Severe hypoxemia.

84. What is APRV more useful for improving: oxygenation or alveolar ventilation?  
APRV is more useful for improving alveolar ventilation.

85. In pressure-controlled ventilation, what are the set variables and what varies?  
The clinician sets inspiratory time or I:E ratio and respiratory rate; flow varies based on patient demand, and tidal volume varies with compliance and resistance.

86. What are two key advantages of pressure ventilation?  
Peak inspiratory pressure is kept constant, and flow adjusts to meet patient demand.

87. What is a primary disadvantage of pressure ventilation?  
Tidal volume varies with compliance and resistance, which may lead to unpredictable blood gas alterations.

88. What is the formula for mean airway pressure in constant pressure ventilation?  
MAP = (PIP – PEEP) × (Ti / Ttot) + PEEP

89. In volume ventilation, what causes changes in peak inspiratory pressure?
Changes in airway impedance, such as compliance and resistance.

90. In pressure-controlled ventilation, which variable is constant and which varies with impedance?
Peak inspiratory pressure is constant; tidal volume varies with impedance.

91. Who determines the flow pattern in volume-controlled ventilation?  
The clinician sets the flow pattern.

92. What are common flow patterns used in volume-controlled ventilation?  
Square (rectangular), ramp (accelerating or decelerating), or sinusoidal waveforms.

93. How does the waveform impact ventilation?  
It influences mean airway pressure.

94. What are the set parameters in volume-controlled ventilation?  
Tidal volume, flow rate and pattern, and respiratory rate.

95. In volume control, how are machine- and patient-triggered breaths delivered?  
Both are delivered with the same preset parameters.

96. In pressure control ventilation, what determines the flow delivery?  
Flow is variable and based on patient demand.

97. What are the main clinician-controlled settings in pressure control ventilation?  
Inspiratory pressure, inspiratory time or I:E ratio, and respiratory rate.

98. What does tidal volume depend on in pressure-controlled ventilation?  
It depends on patient lung compliance and airway resistance.

99. What type of flow waveform is associated with pressure-controlled ventilation?  
A decelerating flow waveform.

100. What is a key advantage of volume-controlled ventilation?  
It delivers a consistent tidal volume, ensuring stable alveolar ventilation.

Final Thoughts

Pressure-controlled ventilation is a valuable mode for managing patients with fragile lungs or conditions that require tight control of airway pressures. It prioritizes safety by capping inspiratory pressure, offering protection against ventilator-induced lung injury.

However, because it does not ensure a fixed tidal volume, it requires vigilant monitoring and frequent reassessment to prevent hypoventilation or under-support. For respiratory therapists and physicians, mastering this mode is critical for optimizing patient outcomes in complex and dynamic clinical environments.