Mechanical Ventilation Monitoring Overview vector

Mechanical Ventilation Monitoring: An Overview (2024)

by | Updated: May 16, 2024

Mechanical ventilation is a critical life-support technique used in medical settings to assist or replace spontaneous breathing in patients who are unable to breathe adequately on their own.

Mechanical ventilation monitoring is the continuous and detailed assessment of a patient’s respiratory status and the performance of the ventilator to ensure optimal respiratory support.

This article provides an overview of mechanical ventilation monitoring, exploring its importance, the various methods employed, and the key parameters that healthcare professionals must observe to ensure optimal patient care.

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What is Mechanical Ventilation Monitoring?

Mechanical ventilation monitoring involves tracking and adjusting a ventilator’s parameters to ensure optimal respiratory support for patients unable to breathe independently. It includes monitoring oxygen levels, airflow, pressure, and patient-ventilator interaction, crucial for patient safety and effective treatment.

Monitoring patient on the mechanical ventilator vector

Parameters to Monitor in Mechanically Ventilated Patients

In mechanically ventilated patients, various parameters are closely monitored to ensure effective and safe treatment.

These include:

Note: These parameters collectively provide a comprehensive view of the patient’s respiratory and overall health status while on mechanical ventilation.

Vital Signs

Monitoring vital signs in mechanically ventilated patients is crucial. It includes checking heart rate, blood pressure, temperature, and oxygen saturation levels.

These indicators provide essential information about the patient’s overall physiological state, helping healthcare professionals assess the effectiveness of ventilation and identify any acute changes requiring intervention.

Breath Sounds

Assessing breath sounds involves using a stethoscope to listen for normal and abnormal respiratory sounds.

This practice is vital for mechanically ventilated patients to detect issues like secretions, obstructions, or pneumothorax.

Regular monitoring helps ensure the ventilator is effectively supporting the patient’s breathing.

Chest Imaging

Chest imaging, such as x-rays or CT scans, is essential for evaluating lung conditions and ventilator effects in mechanically ventilated patients.

These images help detect complications like pneumothorax, pneumonia, or misplacement of the endotracheal tube, guiding adjustments in ventilation settings, or additional treatments.

Chest Movement

Observing chest movement provides insights into the mechanical ventilation’s effectiveness and the patient’s respiratory effort.

Symmetrical and adequate chest expansion indicates proper ventilator function and lung inflation, while asymmetrical or inadequate movement may signal issues requiring adjustments in ventilator settings or further evaluation.

Fluid Balance

Monitoring fluid balance in mechanically ventilated patients involves tracking intake and output to manage hydration and electrolyte levels.

This is crucial to prevent fluid overload, which can lead to pulmonary edema, and to ensure adequate hydration, which can affect lung function and mucus production.

Accurate fluid management is essential for optimal respiratory care and overall health, especially in patients with congestive heart failure (CHF).

Blood Gas Results

Blood gas analysis is critical in managing mechanically ventilated patients.

It measures oxygen and carbon dioxide levels in the blood, indicating how effectively the lungs are exchanging gases.

Results guide adjustments in ventilation settings and oxygen delivery, ensuring adequate oxygenation and carbon dioxide removal.


Capnography monitors the concentration of carbon dioxide in exhaled air, providing real-time feedback on a patient’s ventilatory status.

This noninvasive method is vital in mechanically ventilated patients to assess ventilation efficiency, detect respiratory changes quickly, and guide adjustments in ventilatory support.

Cerebral Perfusion Pressure

Monitoring cerebral perfusion pressure (CPP) is essential in mechanically ventilated patients, especially those with neurological concerns.

CPP assesses the pressure needed to ensure blood flow to the brain, helping to avoid conditions like ischemia or increased intracranial pressure, which can be impacted by ventilation settings.

Mechanical Ventilation Monitoring Practice Questions

1. What should a respiratory therapist do before a vent check while monitoring a patient on the ventilator?
Establish a baseline for the initial assessment.

2. What do you look for before a visual assessment?
Look at the patient’s chest x-ray, labs, medications, history, and previous vent checks. Make sure there is an ambu bag in the room, and if the settings have changed from your last vent check, see if the patient can tolerate those settings.

3. When should you do a vent check?
Timed checks, when there are changes (document the change and do another vent check), when there are problems or alarms after you obtain an ABG, and to monitor the patient’s hemodynamic values.

4. Why do we do a thorough vent check first thing in the morning?
To establish a baseline.

5. What should you think of when looking at the patient’s mean airway pressure?
Think oxygenation, because you can increase the MAP to improve the patient’s oxygenation status.

6. How can you increase the MAP?
Increase the level of PEEP

7. What is the apnea alarm typically set at?
20 seconds

8. What should the high/low respiratory rate be set at?
It should be set at 10 above/below the average but no more than 35 and no less than 8.

9. What should the high/low tidal volume be set at?
It should be set at 100 above/below the average tidal volume.

10. What should the high/low minute ventilation be set at?
It should be set a 2 L above/below the average minute ventilation.

11. What should the high-pressure alarm be set at?
It should be set as 10 above the PIP, and no more than 35.

12. What will happen if there is a loss of compressed air?
The patient will get 100% oxygen.

13. What type of trigger is best for reducing the work of breathing?
Flow trigger

14. Monitoring the functions of the ventilator system should be performed how often?
As frequently as the clinical situation dictates.

15. How often should most patient/ventilator systems be evaluated?
Every 2, 4, and 8 hours in acute care settings.

16. Who requires more frequent ventilator checks?
Unstable patients

17. Who requires evaluation only every 4 hours?
Chronic ventilator patients

18. What are the measurements that are taken when a patient is spontaneously breathing?
Tidal volume, respiratory rate, minute ventilation, vital capacity, MIP, and MEP.

19. What measurements are taken during mechanical ventilatory support?
Exhaled tidal volume, respiratory rate, inspiratory flow, alveolar minute ventilation, deadspace ventilation, and minute ventilation.

20. What is the actual volume delivered to the patient that will be lower than the set tidal volume?
Exhaled tidal volume

21. How is exhaled tidal volume calculated?
Minute ventilation + respiratory rate

22. How is minute ventilation calculated?
Respiratory rate x tidal volume

23. How is alveolar minute ventilation calculated?
(Vt – Vd) x RR

24. When calculating minute ventilation, what should be used as the Vd?
The actual weight of the patient (i.e., 1 mL per lb. of ideal body weight).

25. What is the best way to increase alveolar ventilation?
Increase the tidal volume

26. What is known as the amount of circuit tubing between the patient and the wye adapter in the ventilator circuit?
Mechanical deadspace

27. What are the two types of compliance that can be monitored in order to monitor airway pressures to detect changes in lung compliance and airway resistance?
Dynamic and static compliance

28. What is the formula for finding dynamic compliance?
Exhaled volume / PIP – PEEP

29. What is the formula for finding static compliance?
Exhaled volume / Plateau – PEEP

30. What is the normal value for static lung compliance?
60 to 100 mL/cm H2O

31. When and how is plateau pressure measured?
At the end of inhalation with a breath-hold maneuver.

32. What does increasing airway pressures indicate?
It indicates that the lung is becoming more difficult to ventilate.

33. What are two reasons that airway pressure increases during mechanical ventilation?
(1) Increasing airway resistance and (2) Decreasing lung compliance

34. What is the value for normal airway resistance?
0.6 to 2.4 cm H2O/L/min/sec

35. What is known as the frictional force that must be overcome during breathing?
Airway resistance

36. For an intubated patient, what may the airway resistance value reach?
6 cm H2O/L/sec

37. Increasing airway resistance does what to the PIP?
It increases

38. With increasing airway resistance, what does the plateau pressure do?
It stays constant.

39. With increasing airway resistance, how can it be calculated?
PIP – plateau pressure

40. What are two common causes of increased airway resistance, and what are their treatments?
(1) Secretions in the airway, which is treated by suctioning, and (2) Bronchospasm, which is treated with a bronchodilator.

41. With decreasing lung compliance, what will the PIP do?
It will increase.

42. With decreasing lung compliance, what will the plateau pressure do?
It will increase.

43. What are the common causes of decreasing lung compliance, and what are their treatments?
Atelectasis, pulmonary edema, ARDS, and pneumonia; treatment involves increasing the PEEP and treating the underlying causes.

44. What is the average pressure transmitted to the airway from the beginning of one breath to the beginning of the next?
Mean airway pressure (Paw)

45. What are the controls that directly affect Paw?
PIP, respiratory rate, inspiratory time, PEEP, peak flow, tidal volume, and inflation hold.

46. What is the most influential control that directly affects Paw?

47. What is the typical Paw value for a patient with normal compliance and resistance?
5 to 10 cmH2O

48. What is the typical Paw value for a patient with an obstructive disease?
10 to 20 cmH2O

49. What is the typical Paw value for a patient with ARDS?
15 to 30 cmH2O

50. What formula is used to calculate the work of breathing?
Change in pressure x change in volume

51. What two pieces of equipment can be used to measure the work of breathing?
Manometer or spirometer

52. What is the normal value for work of breathing?
0.5 + – 0.2 joules/L

53. Can the work of breathing be easily measured during spontaneous breathing?

54. What does Paw primarily affect?

55. Can the work of breathing be measured during mechanical ventilation?

56. Does the work of breathing increase or decrease when a patient has a pulmonary disease?
It increases

57. Increased work of breathing can be detected clinically by noting what three things?
Accessory muscle use, tachypnea, and retractions.

58. When inspiratory muscles tire, the tidal volume decreases, and what happens to the respiratory rate?
It increases

59. What are the early signs of hypoxia?
Tachycardia, dyspnea, shortness of breath, restlessness, tachypnea, and diaphoresis.

60. If left uncorrected, hypoxia in late stages will result in what?
Bradycardia, lethargy, fatigue, and cyanosis.

61. What is cyanosis?
A bluish discoloration of nail beds and mucus membranes caused by an excess in desaturated hemoglobin in the blood.

62. Mental alertness and pupillary response are signals of what?
They are signals that cerebral perfusion is adequate.

63. Breath sounds that were diminished in an area where they were previously normal may indicate what?
Right mainstem intubation, plugged ET tube, mucus plugging, or a pneumothorax.

64. What is a right mainstem intubation?
It occurs when the endotracheal tube is pushed in too far, resulting in no gas flow to the left lung. Breath sounds will be absent on the left side.

65. What is a pneumothorax?
A medical condition characterized by the accumulation of air in the pleural space, causing the lung to collapse.

66. What is the purpose of a ventilator circuit change?
To limit the occurrence of nosocomial infection, to maintain circuit integrity, and to provide a clean circuit appearance.

67. What can changing ventilator circuits too frequently cause?
Ventilator-associated pneumonia (VAP)

68. How often should you change the ventilator circuit?
Only as needed (i.e., PRN), when it is damaged, or when it’s visibly soiled.

69. What is the first immediate response to hypoxemia?

70. What is the late response to hypoxemia?

71. Cyanosis may be seen with what?
Hypoxemia or decreased cardiac output.

72. How can you increase the oxygenation of a patient with ARDS who is on the ventilator?
Increase the PEEP

73. What are the disadvantages of PEEP?
Barotrauma, decreased cardiac output, hypotension, decreased renal perfusion, decreased urinary output, and increased intracranial pressure.

74. What should you monitor once a mechanically ventilated patient has a PEEP of 10 cmH2O?
It is critically important to monitor their hemodynamics, including arterial blood pressure, Qt, PA pressure, and PCWP.

75. You should begin treating a patient’s auto-PEEP once the level is what?
10.0 cmH2O or higher

76. An FIO2 greater than 0.5 to 0.6 can lead to what?
Oxygen toxicity

77. Too much PEEP can cause what?
Barotrauma and hemodynamic instability.

78. You should increase PEEP in increments of what?
Increase PEEP in increments of 2 until it reaches 10.0 cmH2O.

79. You should increase PEEP incrementally until what occurs?
A hemodynamic deficit occurs.

80. Increased oxygenation will be attained by increasing what?
By increasing the FiO2 above 50%.

81. PEEP increases the FRC by raising what?
By raising the patient’s baseline.

82. If a patient has atelectasis, you can suspect that FRC is what?

83. Auto-PEEP is an important and sometimes serious type of air trapping that is exhibited by what type of patient?
By patients who are not allowed adequate exhalation time.

84. Why is auto-PEEP often seen in the over-compliant lungs of COPD patients?
The COPD lung has lost elasticity (i.e., elastic recoil) and requires a longer time to deflate to its baseline.

85. COPD lungs contain obstructed airways due to what?
Due to secretion retention and bronchospasm; therefore, the expiratory flow is decreased.

86. What patients should be evaluated for auto-PEEP risk factors?
Patients with increased airway resistance, narrowing, and collapse; patients with overly compliant lungs (i.e. emphysema); and patients with a long inspiratory time, short expiratory time, high frequency, and large tidal volumes.

87. How is auto-PEEP eliminated?
By increasing the inspiratory flow rate, increasing the set PEEP, decreasing the mechanical tidal volume, decreasing the mechanical frequency, and changing the inspiratory flow rate waveform.

88. What five vital signs should be monitored during mechanical ventilation?
Heart rate, respiratory rate, oxygen saturation, blood pressure, and temperature.

89. If bradycardia is present during mechanical ventilation, what is the most likely cause?

90. What condition causes hypertension during mechanical ventilation?
Fluid overload (i.e., hypervolemia)

Final Thoughts

Mechanical ventilation monitoring is an essential aspect of patient care in critical situations, playing a pivotal role in the safety and effectiveness of ventilatory support.

Through diligent observation of a range of parameters and the careful adjustment of ventilator settings, healthcare professionals can significantly improve patient outcomes.

This article has outlined the key facets of this complex yet vital process, highlighting its significance in modern medical practice and the critical role it plays in managing patients on the ventilator.

John Landry, BS, RRT

Written by:

John Landry, BS, RRT

John Landry is a registered respiratory therapist from Memphis, TN, and has a bachelor's degree in kinesiology. He enjoys using evidence-based research to help others breathe easier and live a healthier life.


  • Chang, David. Clinical Application of Mechanical Ventilation. 4th ed., Cengage Learning, 2013.
  • Rrt, Cairo J. PhD. Pilbeam’s Mechanical Ventilation: Physiological and Clinical Applications. 7th ed., Mosby, 2019.
  • Faarc, Kacmarek Robert PhD Rrt, et al. Egan’s Fundamentals of Respiratory Care. 12th ed., Mosby, 2020.
  • “Settings and Monitoring of Mechanical Ventilation during Physical Therapy in Adult Critically Ill Patients: Protocol for a Scoping Review.” PubMed Central (PMC), 2019.
  • Rackley CR. Monitoring During Mechanical Ventilation. Respir Care. 2020.

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