The High-Flow Oxygen and Swallowing Connection
High-flow nasal cannula (HFNC) therapy delivers a precise mixture of heated and humidified oxygen at high rates, often between 20 and 60 liters per minute. Unlike traditional oxygen masks, which must be removed for eating, HFNC leaves the mouth free, theoretically permitting oral intake. However, the high gas flow and pressure can significantly impact the precise coordination of breathing and swallowing, which share a common pathway.
Research on how HFNC affects swallowing function, or dysphagia, presents conflicting results. Some studies in healthy individuals have shown that higher flow rates can increase the sensation of choking or make swallowing more difficult. In contrast, other studies suggest that in some patients, HFNC might actually support swallowing by improving breath-swallow coordination. This uncertainty underscores the need for careful, individualized assessment rather than a one-size-fits-all approach.
Clinical Perspectives on Feeding with HFNC
A survey of healthcare professionals revealed differences in opinion on feeding practices for patients on HFNC. Many physicians, respiratory therapists, and dietitians felt that a stable patient not at imminent risk of intubation could safely have an oral diet. However, a significant majority of speech-language pathologists (SLPs), who specialize in swallowing disorders, were in favor of a bedside or instrumental swallow examination before initiating an oral diet. This highlights the importance of incorporating specialized swallowing expertise into the decision-making process.
Evaluating Safety: Who Can Eat While on High Flow Oxygen?
The decision to allow oral intake is not based solely on the presence of HFNC but on the patient's overall clinical presentation. A team of healthcare professionals, including doctors, nurses, dietitians, and SLPs, must consider multiple factors. A patient with improving respiratory function and a strong cough is a better candidate for oral feeding than a patient whose respiratory status is deteriorating.
Important Considerations for Eating with HFNC
- Overall Health Status: Assess the patient's underlying medical condition, frailty, and cognitive status. A clear and alert patient is better able to manage swallowing.
- Respiratory Stability: The patient should not be in significant respiratory distress. Their breathing should be stable, and their oxygen saturation should not drop significantly during meals.
- Risk Factors for Dysphagia: Evaluate any pre-existing swallowing difficulties or conditions that might increase aspiration risk.
- Instrumental Swallowing Assessment: For patients with known risks, an instrumental assessment like a Flexible Endoscopic Evaluation of Swallowing (FEES) can provide a definitive look at swallowing mechanics.
- Flow Rate and Subjective Experience: Pay attention to the patient's subjective feeling of difficulty. Healthy individuals have reported increased difficulty swallowing at higher flow rates.
Strategies for Safe Oral Intake on HFNC
If oral feeding is deemed safe, specific strategies can minimize risk and improve success. These adjustments are crucial for helping the patient meet their nutritional needs safely while conserving energy for breathing.
Practical Strategies for Eating
- Ideal Positioning: Ensure the patient is sitting fully upright (e.g., at a 90-degree angle) to aid in the passage of food and liquids and reduce the risk of aspiration.
- Small, Frequent Meals: Large meals can be fatiguing. Smaller, more frequent meals can be easier to manage and less taxing on the respiratory system.
- Texture Modification: The SLP may recommend a diet of soft, moist, and easy-to-chew foods, along with thickened liquids, to improve control and reduce aspiration risk.
- Chew Thoroughly: Encourage the patient to chew all food completely before swallowing to prevent large pieces from entering the airway.
- Close Monitoring: Watch for signs of distress during and after eating, such as coughing, choking, or a drop in oxygen saturation. If these occur, stop feeding immediately and alert the care team.
- Optimal Timing: Schedule meals during periods of the day when the patient feels most rested and stable.
Comparison of Feeding Methods with HFNC
| Feature | Oral Feeding | Enteral Feeding (via NGT) | Parenteral Nutrition (IV) |
|---|---|---|---|
| Method | Eating and drinking by mouth | Tube delivering nutrients to stomach | IV administration of nutrients |
| Best For | Stable patients with low aspiration risk | Malnourished, high aspiration risk, or poor oral intake | Prolonged starvation, severe GI issues, or other complications |
| Benefits | Psychological comfort, maintains oral motor function | Reliable and sufficient calorie/protein delivery | Bypasses swallowing and GI tract entirely |
| Drawbacks | Aspiration risk, requires significant patient effort | Potential for reflux, gastric insufflation, discomfort | Higher risk of infection, metabolic complications |
Alternatives When Oral Feeding Is Unsafe
If oral feeding is not safe or cannot provide sufficient calories, alternative nutritional support methods are necessary to prevent malnutrition, which can impede recovery.
Enteral Feeding (Tube Feeding)
Enteral nutrition involves delivering nutrients directly to the stomach or small intestine via a feeding tube, often a nasogastric tube (NGT). This is a common method for patients who are malnourished or have a high aspiration risk. However, some studies have raised concerns that high flow rates might increase the risk of gastric reflux and aspiration even with tube feeding. These potential issues must be managed by the healthcare team.
Parenteral Nutrition
For patients with prolonged swallowing difficulties or other contraindications for enteral feeding, parenteral nutrition may be considered. This involves administering liquid nutrients directly into a vein. It is often used when the gastrointestinal tract cannot be used or when other methods are inadequate. While effective, it carries risks and is generally reserved for more critical cases.
Conclusion
While high-flow oxygen does not automatically prohibit eating, it introduces significant considerations regarding patient safety and swallowing function. The ability to eat while on this therapy is highly individualized and requires a comprehensive assessment by the healthcare team, including a speech-language pathologist. Stable patients who pass a swallow evaluation may be able to eat, especially with modifications to diet and technique. For others, alternatives like enteral or parenteral nutrition are essential to ensure adequate calorie and protein intake for recovery. It is vital for patients and their families to work closely with their medical team to determine the safest and most effective approach to nutrition.
For a deeper dive into the relationship between High Flow Nasal Oxygen (HFNO) and dysphagia, particularly concerning patient assessments, clinicians can refer to narrative reviews available on platforms like the National Institutes of Health (NIH) website.
