Can I feed my patient when she is on high-flow nasal cannula (HFNC) with FiO2 of 65% and flow rate of 60 liters per minute (lpm)? I have concerns that the high airflow will increase the risk of aspiration.
There have been many similar questions in online discussion groups, especially during this 2020 COVID-19 pandemic.
“There is no rule of thumb for this question,” responded Dr. James Coyle, PhD, CCC-SLP, BCS-S in a November, 2020 post. Coghlan & Skoretz (2017, p78) also lamented about the “paucity of the literature” regarding starting oral feeding when someone is on a high-flow nasal cannula.
That makes us uncomfortable. Speech-language pathologists (SLPs) want evidence-based answers, and we want them now. We want to do what is best for our patients in intensive care units (ICU) around the world.
Let’s start with a description of the HFNC:
It is an oxygen delivery device with a wide-bore silicon nasal cannula (filling about 50% of the internal diameter of the nares per Parke, et al., 2009). It delivers high airflows of up to 60-70 liters per minute (lpm). This air is heated to body temperature (37°) and humidified (100% relative humidity / 44 mg H2O per liter and contains a percentage of oxygen gas (i.e., FiO2 or Fraction of Inspired Oxygen) (Parke, et al., 2011). Humidification can reduce discomfort, sinus pain, and airway dryness, which can all occur with traditional oxygen delivery through a standard plastic nasal cannula.
So, back to this lack of definitive answers to our clinical question about HFNC…
If you have reviewed just a few articles, you may see the following quotes:
- “HFNC’s value is not limited to ventilation and oxygenation, as it may also allow for oral feeding” (Alshuwaikhat, et al., 2020). Many articles refer to the availability of the mouth, as these systems do not require a face mask.
- “Among healthy adults, regardless of age, saliva swallow frequency was not significantly affected by HFNC at any flow.” (Alshuwaikhat, et al., 2020)
- “Nasal high-flow may allow continuation of oral intake without aspiration during oxygen therapy (p 915).” That last one was really a stretch of a conclusion by Sanuki and colleagues (2017), but more on research problems later.
Or, you may start getting confused when you read:
- HFNC is common, but the “impact on the respiratory-swallowing sequence has not been closely researched, and, therefore, its impact on initiation of safe oral intake is in question…,” per Kortney Eng and colleagues, 2019, p 1519.
- The “effects on swallowing are unclear,” (Flores, et al., 2019, p522).
- “HFNC may cause unwanted complications during eating and swallowing,” (Allen & Galek, 2020).
It becomes clear that we have to carefully analyze many research articles, thoroughly review the medical record, and we have to know our patients well. Then, we can try to apply a set of general criteria and guidelines to each person, knowing they are an individual. Can we come up with a rough set of guidelines by the end of this article? Read on, BUT do not stop asking questions!! For example, does the population tested in a particular piece of research even apply to my specific patient?
I hope this blog will start you on your journey. Our endpoint is to build a critical thinking framework in our SLP brains to apply to each individual who is on high-flow nasal cannula (HFNC) within a person-centered care process. The framework at the end of the blog is not a researched-validated tool, and it will certainly not direct you to a diet recommendation; rather, it will guide your thinking, questions, and further testing (e.g., instrumental evaluations) so that you can demonstrate caution with these individuals who are critically ill.
What other questions will you ask? I hope you will share thoughts, experiences, and questions in the comment section below. We are #AllinThisTogether…
But first, I must thank my SLP community for the inspirations for this blog (no financial disclosures with these shout-outs):
Inspiration #1: American Speech-Language & Hearing Association’s (ASHA) Special Interest Group 13: Swallowing and Swallowing Disorders (SIG13) has an online community page where you can ask questions and contribute. There are frequent questions about starting oral intake in someone on high-flow nasal cannula. Check out these community pages at https://community.asha.org/home. For more resources and answers to your dysphagia questions, become a SIG13 member, and find the “affiliates-only online community” here: https://www.asha.org/SIG/13/.
Inspiration #2: DysphagiaCafe’s Webinar (November, 2020) titled: “Room Air to Mechanical Ventilation and Everything In-between” by Aimee Cardoso, RRT, BSRT (@Breatheeasy_RRT on Instagram). It was so informative and organized, reviewing the least to the most invasive means of respiratory support. She smartly defined key terms for us speech-language pathologists, such as FiO2, which stands for Fraction of Inspired O2. It is the amount of oxygen concentration delivered as a gas in a particular respiratory support device. Did you know that we are all on an FiO2 of 21%, meaning that room air is 21% oxygen? Cardoso noted that 100% FiO2 is not common, as alveoli damage and oxygen toxicity can happen if you are on high percentages of FiO2 (e.g., 100% FiO2 for more than 24 hours)? She reviewed airflow and the ranges of liters per minute in the common respiratory support devices, for examples:
- Traditional O2 via nasal cannula, which can only go up to 6 lpm;
- Venturi mask, which has color-coded adapters for each specific FiO2 target and goes up to 15 lpm;
- Non-rebreather/NRB, which delivers up to 90% FiO2 and has flow rates from 10 to 15 lpm;
- High flow nasal cannula/HFNC, which can deliver up to 100% FiO2 and flow rates of up to 60-70 lpm).
To clarify, this blog is not about how much oxygen people are receiving with their respiratory support. Instead, we want to explore the effects of the amount of flow and how that may affect the person’s swallowing.
“It is the flow rate that is potentially problematic in terms of increasing pharyngeal airway pressure,” Coyle clarified in one recent post on SIG13 (2020). In order to get more information on that that issue and more, we need to take the following path:
A. Background on HFNC & Clarifications
1. Why so many labels and acronyms?
2. Why is HFNC needed?
3. Potential benefits of HFNC.
4. How much pressure is there?
B. Research on HFNC & Its Problems
1. Are study participants similar to my patient population?
2. Major problems with some prior research
- Just because it is published…
- Make sure to read the entire article.
C. Research on HFNC that Included Instrumental Evaluations
D. Are We Close to Guidelines?
To read the full article, please go to Swallowstudy.com HERE
References from the original article posted on Swallowstudy.com
Allen, K. & Galek, K. (2020). The influence of airflow via high-flow nasal cannula on duration of laryngeal vestibule closure. Dysphagia, published online https://doi.org/10.1007/s00455-020-10193-0
Alshuwaikhat, H., Scott, B. & LaGorio, L. (2020, October). The Impact of High-Flow Nasal Cannula on Swallow Function. Respiratory Care, 65 (Issue Suppl 10) 3440132.
http://rc.rcjournal.com/content/65/Suppl_10/3440132 — only available in this abstract form
Coghlan, K., & Skoretz, S. (2017). Breathing and swallowing with high flow nasal cannula therapy. Perspectives of the ASHA Special Interest Groups, 2(3), 74–81.
Coyle, J. L. (2010). Ventilation, respiration, pulmonary diseases, and swallowing. SIG 13 Perspectives on Swallowing and Swallowing Disorders (Dysphagia), 19(4), 91–97.
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Eng, K., Flores, M. J., Gerrity, E., Sinha, N., Imbeau, K., Erbele, L. & Yeh, C. (2019, December). Evaluation of Swallow Function on Healthy Adults While Using High-Flow Nasal Cannula. Perspectives of the ASHA Special Interest Groups, 4, 1516-1524. Downloaded from: https://pubs.asha.org
Flores, M. J., Eng, K., Gerrity, E., & Sinha, N. (2019). Initiation of oral intake in patients using high flow nasal Cannula: A retrospective analysis. Perspectives of the ASHA Special Interest Groups, 4, 522–531. Downloaded from: https://pubs.asha.org
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DOI https://doi.org/10.1007/s00784-016-1822-3
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