As Respiratory Therapists, we spend a lot of time focusing on mechanical ventilators. We often learn about the different modes, settings, and how they function.

With that said, unfortunately, we often overlook the process that entails the initiation of mechanical ventilation.

When setting up a patient on the ventilator, you must understand the indications, contraindications, and initial settings to use. Each, of which, may be different depending on a patient’s condition.

We created this study guide to help make the learning process easier for you. We also listed out some practice questions for your benefit as well. So, if you’re ready, let’s get into it.

What are the Goals of Mechanical Ventilation?

A mechanical ventilator in and of itself does not cure a patient of their initial underlying condition. However, it’s meant to provide breathing support until their condition is treated and reversed.

With that said, here are the primary goals of mechanical ventilation:

  • To improve gas exchange
  • To reverse hypoxemia
  • To reverse acute respiratory failure
  • To provide relief for respiratory distress
  • To reverse respiratory muscle fatigue
  • To improve pulmonary mechanics
  • To prevent or reverse atelectasis
  • To improve lung compliance
  • To prevent lung injury
  • To maintain lung and airway functionality
  • To prevent respiratory muscular dystrophy

Again, the goals of mechanical ventilation will be different for each and every patient. These are just a few of the most common examples.

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What are the Indications for Mechanical Ventilation?

As a general rule of thumb, mechanical ventilation is indicated whenever a patient’s spontaneous breathing is not adequate to sustain life. In such a case, a mechanical ventilator would be needed in order to support the patient until their underlying condition is reversed.

Here are some of the common indications for mechanical ventilation:

  • Insufficient oxygenation
  • Insufficient ventilation
  • Acute Lung Injury (ALI)
  • Severe asthma
  • Severe hypotension
  • Inability to protect the airway

Be sure to check out our Mechanical Ventilation Basics guide if you want more details on the indications for mechanical ventilation.

What are the Contraindications for Mechanical Ventilation?

A patient cannot survive without adequate ventilation and oxygenation. This means that there are no absolute contraindications for mechanical ventilatory support.

If a patient needs help breathing and requires full ventilatory support, they are likely going to need mechanical ventilation. There really is no way around it.

The only contraindication for mechanical ventilation is if the patient legally and specifically states that they do not wish to be intubated or receive life support.

This is referred to as a DNI order, or Do Not Intubate.

In such a case, the patient may receive Bilevel Positive Airway Pressure (BiPAP) instead as a form of Noninvasive Ventilation.

What are the Initial Ventilator Settings?

Once it has been determined that mechanical ventilation is indicated, you must know how to properly input the initial settings.

Each mechanical ventilator machine is different, so be sure to abide by the guidelines provided by the manufacturer. However, here are some general guidelines that you can use when determining a patient’s initial ventilator settings:

  • Mode – Any operational mode will work when setting up the initial ventilator settings. It’s important not to get too caught up deciding on the right mode. This is especially true for the TMC Exam. With that said, just as a reminder, you can select A/C in the patient needs full support or SIMV if they only need partial support.
  • Tidal Volume – The initial tidal volume setting should be 5 – 10 mL/kg of the patient’s ideal body weight (IBW).
  • Frequency – The initial frequency setting should be 10 – 20 breaths/min.
  • FiO2 – The initial FiO2 setting should be 30 – 60% unless the patient was previously receiving an higher percentage of oxygen before intubation. Then you would use that previous FiO2. Strive to provide the lowest concentration of oxygen that’s possible to maintain a normal PaO2. An FiO2 up to 100% as an initial setting is appropriate for patients with severe oxygenation issues.
  • Flow Rate – The initial flow setting should be 40 – 60 L/min.
  • I:E Ratio – The initial I:E ratio setting should be 1:2 – 1:4.
  • Sensitivity – The initial sensitivity setting should be between -1 and -2 cmH2O.
  • PEEP – The initial PEEP setting should be 4 – 6 cmH2O

Again, in order to understand the initiation of mechanical ventilation, it’s extremely important to learn about the initial setting to use when setting up a patient on the ventilator.

This book (in paperback format) has sample TMC Practice Questions on mechanical ventilation.

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Initiation of Mechanical Ventilation Practice Questions:

1. When initiating mechanical ventilation, what mode should you choose?
The mode doesn’t matter as long as you can set a respiratory rate for the patient. Any mode is acceptable for initiating mechanical ventilation.

2. Name 2 full support ventilator modes in which you can set a respiratory rate:
Controlled Mandatory Ventilation (CMV); and Assist control (A/C)

3. Name 2 partial support ventilator modes in which you can set a respiratory rate:
Intermittent Mandatory Ventilation(IMV); and Synchronized intermittent mandatory ventilation(SIMV)

4. What are the 4 methods of full ventilatory support?
(1) Initiating mechanical ventilation (2) Maintenance of mechanical ventilation (3) Discontinuing/weaning mechanical ventilation (4) General considerations in mechanical ventilation

5. What two settings on the ventilator allow you to manage the patient’s CO2?
Respiratory rate and tidal volume

6. What should the initial setting for respiratory rate be for a new mechanical ventilation patient?
10-20 breaths per minute

7. What should the initial setting for tidal volume be for a new mechanical ventilation patient?
5-10 ml/kg of ideal body weight

8. What should the initial setting for pressure be for a new mechanical ventilation patient?
Less than or equal to 35 cmH2O

9. What should the initial setting for FiO2 be for a new mechanical ventilation patient?
40 – 60% (or set to the same level prior to ventilation)

10. What should the initial setting for PEEP be for a new mechanical ventilation patient?
2 – 6 cmH2O

11. Spontaneous tidal volume is driven by _____________ and should not be considered on the initiation of mechanical ventilation.
Pressure support

12. What two options on the ventilator allow you to manage the patient’s O2 (SaO2)?
FiO2 and PEEP

13. Which patients should be set at 40% FiO2 on initiation of mechanical ventilation?
Patient with non-cardiopulmonary issues

14. Which patients should be started at an FiO2 of 100% on the initiation of mechanical ventilation?
Patients with cardiopulmonary issues

15. What is the FiO2 exception rule for initiating mechanical ventilation?
A patient with a known FiO2 on a different device (i.e. CPAP or BiPAP) should be kept on that same FiO2 when put on the mechanical ventilator

16. All patients being set up on mechanical ventilation must have what done?
An ABG within 30 minutes of being placed on the ventilator

17. What should the tidal volume alarm be set at?
+/- 100 ml of the patient’s exhaled tidal volume; or +/- 10% of the patient’s exhaled tidal volume

18. What should the respiratory rate alarm be set at?
10 – 15 breaths per minutes above their observed rate

19. What should the minute ventilation alarm be set at?
> 10 L/min; or +/- 1 liter of the exhaled minute ventilation

20. What should the PIP alarm be set at?
+/- 10 – 15 cwp, but never greater than 50 cmH2O

21. What should the plateau pressure alarm be set at?
+/- 10, but never greater than 35 cmH2O

22. What are some indications for mechanical ventilation?
Apnea, acute ventilatory failure, impending respiratory failure, severe hypoxemia, surgery, prophylactic support for pulmonary complications

23. What constitutes acute ventilatory failure?
The patient cannot sustain spontaneous ventilation to provide adequate oxygenation and ventilation; pH < 7.25, PaCO2 > 50; COPD (uncompensated respiratory acidosis with PaCO2 above the patients normal value, which will be high)

24. For a patient with a NIF or MIP of less than 20 cmH2O, you should do what in this situation?
Intubate the patient

25. What is the criteria for impending respiratory failure?
Tidal volume < 5 mL/kg of ideal body weight, vital capacity < 10 mL/kg of ideal body weight, respiratory rate >35 or < 10, minute ventilation > 10 L/min, NIF < -20 cwp, RSBI > 105

26. What is an absolute contraindication for initiating mechanical ventilation?
An untreated tension pneumothorax

27. Why would you initially set tidal volumes lower than 8-12 mL/kg of ideal body weight?
Low compliance (ARDS 6 – 8mL/kg), increased compliance, air trapping; or the need for reduced lung volumes (pneumonectomy)

28. What type of ventilation only supports spontaneous breathing and is not needed during the initiation of mechanical ventilation?
Pressure support ventilation

29. What two things should you monitor when using PEEP?
The patient’s blood pressure and their ABG results

30. Why would you increase PEEP?
If the patient has refractory hypoxemia, or already at an FiO2 > 60%

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31. What is the most common method of I:E change?
Changing the flowrate

32. Changes in respiratory rate affect the length of what?
Exhalation

33. Complications of mechanical ventilation include?
Barotrauma/volutrauma, decrease in cardiac output, blood pressure changes; pulmonary infection, tracheal damage, respiratory muscle fatigue, poor nutrition

34. What causes mechanical ventilation failure?
(1) MIP < -20 cmH2O, (2) respiratory rate < 8, (3) minute ventilation < 10 L/min, (4) vital capacity < 10 mL/kg, (5) tidal volume < 5 mL/kg, (6) MEP < 40 cmH2O, (7) VD/VT > 60%, (8) QS/QT >20%

35. What is the other data that may collectively indicate the need for mechanical ventilation?
(1) No chest movement, (2) Absent breath sounds, (3) Hypoventilation (especially in the presence of a suspected drug overdose), (4) Persistent hypoxemia (regardless of the FiO2)

36. In adults, what are the 9 things needed for the initiation of mechanical ventilation?
(1) Rate. (2) Vt. (3) FiO2. (4) PEEP. (5) Mode. (6) Peak Flow. (7) Ideal body weight. (8) Best type of ventilator. (9) Complications associated with positive pressure ventilation.

37. What is the normal FiO2 to initiate mechanical ventilation for an adult?
Use the same FiO2 as the previous if it available. Don’t put the patient on room air (21%). Use 30 – 60% if the previous FIO2 is not known or if they were on room air. Initiate with an FiO2 of 100% if it’s an emergency situation.

38. What is the normal PEEP to initiate mechanical ventilation for an adult patient?
For PEEP, you should use the same as previous (CPAP values/the expiratory side of BIPAP). Or if no previous PEEP then any PEEP under 10 cmH20 is ok.

39. What is the normal mode that should be used to initiate mechanical ventilation on an adult patient?
Any mode is acceptable for initiating mechanical ventilation. All modes will ventilate.

40 What is the normal peak flow to initiate mechanical ventilation on an adult patient?
For peak flow, you must calculate the appropriate flow.

41. What is the normal ideal body weight to initiate mechanical ventilation on an adult patient?
Use the given patient’s weight in kilograms. If it isn’t given, you can use this formula:
IBW = 50 kg + (2 x # of inches over 5 ft. tall)

42. When initiating mechanical ventilation, when should you use a volume-cycled ventilator?
If there is any problem with the lungs. For example; ARDS, pneumonia , COPD etc.

43. When initiating mechanical ventilation, when should you use a pressure-cycled ventilator?
If there is any problem other than with the lungs, that’s when you should use a pressure-cycled ventilator. For example; neurological cases, drug overdose, myasthenia gravis, etc.

44. What are the complications associated with positive pressure ventilation to initiate a mechanical ventilation?
Decreased venous return, decreased urine output, loss of dignity, development of ventilator dependency.

45. How do you monitor a patient receiving mechanical ventilation?
(1) Maintain the vital function of ventilation, (2) Oxygenation and ventilation requires the need to monitor its clinical and lab areas, (3) Watch for a decrease in cardiac function (4) Changes in blood pressure needs to be monitored.

46. What are the central objectives for a patient on mechanical ventilation?
(1) Get them off of the ventilator, (2) Ensure adequate ventilation and oxygenation

47. How do you monitor the readiness to wean or to stop mechanical ventilation?
The patient may be ready to ready to wean if: (1) All vital signs are stable, (2) ABGs are good, (3) Their spontaneous tidal volume is > 5 mL/kg, (4) Their vital capacity is > 10 mL/kg, Their MIP is > 20 cmH20, (6) the QS/QT is < 20%, (7) the Vd/VT is < 60%, (8) The underlying problem has been resolved.

48. What are the 7 Ventilator Modes?
(1) SIMV / IMV, (2) Assist/Control, (3) Control Mode, (4) Pressure Control Ventilation (PCV), (5) Inverse Positive Pressure Ventilation Mode (IPPV), (6) Inspiratory Plateau Mode, (7) High-Frequency Ventilation (HFPPV)

49. What is SIMV/IMV mode?
It is good for weaning, and also good for patients who breathe on their own to a small degree. This mode offers a less likelihood of barotrauma. Be sure to avoid hyperventilation. It is often used on anxious patients until sedation wears off, then a control mode can be used. It consists of a mandatory rate and also allows spontaneous breathing in between the mandatory breaths.

50. What is Assist/Control mode?
It provides a set tidal volume at a set rate. Also, the set tidal volume is delivered even when the patient spontaneously initiates breaths above the set rate. It’s a good mode and works with most patients. Alert patients tend to find it uncomfortable and may need sedation and anxiety controlling medications.

51. What is Control mode?
It is used for unconscious patients. It does not allow patients to determine the rate or tidal volume. For this mode, patients should be sedated or paralyzed. This mode is not common but will provide ventilation just as good as any other mode.

52. What is Pressure Control Ventilation (PCV) mode?
It is used when peak pressures are a primary concern above 50 cmH2O by volume ventilation. There is no tidal volume setting; only inspiratory pressure and inspiratory time. You must set exhaled tidal volume alarms. It is a good mode for high PIP and for hypoxemia patients. It is not a good initial ventilator mode.

53. What is Inverse Positive Pressure Ventilation (IPPV)?
It’s not a good initial mode. It can be used on the same patients as those eligible for pressure control ventilation (ARDS). It may be useful for patients requiring high peak pressures due to low lung compliance.

54. What is Inspiratory Plateau mode?
It helps to improve gas distribution. Also, it can significantly increase mean airway pressure.

55. What is the High-Frequency Ventilation (HFPPV) mode?
Includes a rate at a high frequency. The main controls are drive pressure, inspiratory time, rate, injector line, PEEP, and FiO2. You can use the drive pressure, rate, and %IT to change ventilation.

56. HFPPV Is used on what patients?
Typically use with ARDS patient or other problems with markedly decreased lung compliance

57. What are the ventilator controls that affect the patient’s PaCO2?
Mechanical deadspace, tidal volume and respiratory rate

58. What should we do if PaCO2 is between 35 – 45mmHg, which is the normal range?
Do not make any changes if the PaCO2 is in the normal range

59. What should you do if PaCO2 is high?
First, you should remove deadspace if the PCO2 is only off by 1 point. Second, you should increase the tidal volume, but be sure to stay in the correct range. Third, you should increase the rate, which is the most common, but only choose it if first two are not options, or if the PaCO2 is 4 mmHg more than the target

60. What should you do if PaCO2 is low?
First, add deadspace if PCO2 is only off by 1 point. Second, you should decrease the rate. Third, you should decrease the tidal volume, but stay in normal range.

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61. What should you do if PaO2 is high?
You should decrease the FiO2 until it’s below 60%, then begin lowering the PEEP. If the FiO2 is 60% or below, then immediately focus on the PEEP. You should decrease the PEEP by decrements of 5 cmH2O. Then you can move the FiO2 by 5 – 10% at a time.

62. What does it mean to add Pressure support?
Pressure support helps to overcome the resistance of the circuit tubing during spontaneous breathing. Pressure support helps spontaneous breathing patients accomplish larger tidal volumes. It also helps to wean patient and keep their tidal volume above 5 mL/kg.

63. What are the two types of ventilator alarms?
High-pressure alarm and low-pressure alarm

64. During an intubation for a patient that needs full ventilatory support, what are the three medications that should be given to this patient?
(1) Anectine, (2) Pavulon, and (3) Curare

65. If the patient is under full ventilatory support, in order to relieve pain and anxiety, what are the three medications that should be given?
(1) Morphine, (2) Valium, (3) Versed

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66. While in full ventilatory support, how should you position the patient?
Semi-fowler’s position is the best for gas distribution during mechanical ventilation

67. What are the most common diagnoses requiring mechanical ventilatory support?
Acute respiratory failure, COPD exacerbation, coma, and neuromuscular disease.

68. A brief inspiratory hold may improve what?
The distribution of ventilation and oxygenation.

69. Lung injury is caused by?
It is caused by repetitive opening and closing of unstable lung units. PEEP stabilizes in the open position reducing the likelihood of injury.

70. Which ventilator mode MUST be used when setting up a patient with their initial ventilator settings?
Any operational mode is fine when setting up the initial ventilation settings.

Final Thoughts

As you can see, the initiation of mechanical ventilation is an important topic in the field of respiratory care. Hopefully, you can use this guide to develop a better understanding of the indications, contraindications, and initial settings of mechanical ventilation.

We have separate guides that cover the different Ventilator Settings and Modes of Mechanical Ventilation as well. I think you will find them to be useful.

Thank you so much for reading and as always, breathe easy my friend.

References

The following are the sources that were used while doing research for this article:

  • Chang, David. Clinical Application of Mechanical Ventilation. 4th ed., Cengage Learning, 2013. [Link]
  • Rrt, Cairo J. PhD. Pilbeam’s Mechanical Ventilation: Physiological and Clinical Applications. 7th ed., Mosby, 2019. [Link]
  • Faarc, Kacmarek Robert PhD Rrt, et al. Egan’s Fundamentals of Respiratory Care. 12th ed., Mosby, 2020. [Link]
  • Orebaugh, S. “Initiation of Mechanical Ventilation in the Emergency Department.” PubMed, Jan. 1996, pubmed.ncbi.nlm.nih.gov/8630160.
  • “Mechanical Ventilation.” National Center for Biotechnology Information, U.S. National Library of Medicine, 22 Apr. 2020, www.ncbi.nlm.nih.gov/books/NBK539742.

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