Indications and Contraindications for Spontaneous Modes
Indications
The most important indication for a spontaneous mode is a spontaneously breathing patient. Once that baseline has been satisfied, spontaneous modes can be used for two different ways:
- Weaning: A way to decrease ventilator support to work towards getting the patient off mechanical ventilation, the weaning process is started as soon as the patient is starting to improve. Sedation is decreased and patients are encouraged to start triggering breaths to change to a more spontaneous mode. This weaning will continue with slow decreasing of settings until the patient is on minimal settings. Once the patient is on minimal settings, they will be removed from the ventilator and the endotracheal (breathing) tube is removed. This is referred to as extubation.
- More comfortable ventilation: Spontaneous ventilation is a less invasive ventilation mode that will allow for better mimicking of physiologic breathing that the patient can control. This is a less common and more secondary indication for a spontaneous mode.
A spontaneous mode, because it is patient-driven, is not as good as control modes are at fixing imbalances in CO2 or oxygen levels. Control modes are used to “fix” these imbalances prior to weaning. Therefore, CO2 and O2 levels are the primary indications for a spontaneous mode.
Key Concept
Contraindications
The most important consideration to remember is that most patients that require ventilation are very sick. Their oxygenation is low, and they are not getting rid of CO2 well enough, causing their organs to start shutting down. When patients are that sick, they need to be stabilized first with a lot of support and treatment before they can start taking over their breathing and breathing on their own again. Spontaneous modes only “help” patients take in breaths on their own terms. If the patient is not stabilized and has abnormal arterial levels of CO2 or O2 (described more in Chapter 8 and 9) they are not a candidate for a spontaneous mode.
A good rule of thumb for mode choice is to stabilize them first on control modes, and then, once the patient is stable, decrease sedation enough for them to trigger breaths consistently, and change them over to spontaneous modes.
The presence of any one of the following conditions precludes the use of spontaneous mode:
- No drive to breathe.
- Very poor oxygen status/high CO2 levels requiring full control of the breathing.
- Unstable vitals requiring advanced medical support—patient should be sedated and control ventilated.
Assessing work of breathing (WOB) is a key factor is ventilation. Many healthcare practitioners probably are already skilled in this area. Practicing this skill will improve your eye for key factors to assess work of breathing. WOB is mostly a subjective assessment based on how a patient looks when they breathe, trying to answer questions like:
- How fast are they breathing?
- Are they taking smaller breaths than they should?
- Can you see muscles contracting with every breath?
A helpful mnemonic to assess difficulty breathing is DiapHRaGM (Diaphoresis, Hypoxia, Respiratory rate, Gasping, accessory Muscle use).
Normal breathing is very rhythmic and gentle with very few external changes to a person other than chest and/or belly expansion. In patients who are working, you will see visual signs of distress: diaphoresis, increased respiratory rate, small or sharp breaths similar to gasping, and additional or accessory muscle use for every breath. Additional muscles can be recruited by the patient to try to assist them in taking breaths in. This is a key finding if they are working to breathe.
Increased WOB is noted if the patient’s RR is above physiologic normal (usually >28 bpm for an adult) and they have any of the following:
- intercostal indrawing
- substernal retractions
- scalene muscle use
- sternocleidomastoid muscle contractions
- paradoxical breathing—belly and chest moving in a see-saw pattern
To learn more about spotting accessory muscle use for respiration, watch “Use Accessory Muscles of Respiration” from Doctor’s Hub:
If you require a transcript for this video, please click Watch on YouTube to view the video source. Then, you can access the written transcript from this page.
Start watching people breathing around you. Watch your patients! More practice will help you recognize increased WOB immediately.
Case Studies
We have discussed some indications and contraindications for spontaneous mode use. Now, let’s put it into practice with a few examples where spontaneous modes would likely be used. For each example, ask yourself whether spontaneous modes are being used for (1) weaning or (2) increased comfort.
- Patient A has been ventilated on volume control for three days. His vitals are stable, the health care providers have started decreasing his sedation, and he is breathing above the set Respiratory Rate (RR) on the ventilator. His bloodwork shows normal CO2 levels. The doctor wants to start weaning, or decreasing ventilation support, and work towards extubating him.
Weaning or comfort? A spontaneous mode is indicated here for weaning. This is the most common reason a spontaneous mode is chosen.
- Patient B was intubated yesterday, and her CO2 levels and vital signs are within normal limits. She has started waking up and is asynchronous with the ventilator in pressure control mode. The respiratory therapist has tried to change the settings in pressure control, but cannot fix the patient double-triggering breaths and fighting the ventilator.
Weaning or comfort? A spontaneous mode could be used here for both weaning and comfort. Vitals and bloodwork is good. There is no reason to sedate this patient for a control mode. Change to spontaneous and start weaning!
- Patient C is awake and alert, but tachypneic (or labouring) with increased work of breathing shown with accessory muscle use while breathing. Blood work is showing slightly elevated CO2 levels in the blood. Patient C might be a candidate for a spontaneous mode of ventilation since they are breathing on their own but need a little extra “help” to take away that increased work of breathing. If the blood work did not improve with a spontaneous mode, then a control mode might need to be used.
Weaning or comfort? A spontaneous mode could be tried here for comfort. This patient may not be stable enough on a spontaneous mode. Monitoring and bloodwork should be done, and if the results are worse, the patient will need to be sedated and fully ventilated on a control mode.
