Should we feed NICU infants on HFNC? (high flow nasal cannula)

Should we feed NICU infants on HFNC?(high flow nasal cannula)

The question whether to feed infants in the NICU on HFNC was posted to the ASHA SIG 13 list serve. Dr. Gosa and Dr. Dodrill gave permission for their insightful answer to be reposted here.

Should we feed NICU infants on HFNC?

Dr. Pamela Dodrill and I have discussed this topic at length together, and with many other clinicians and clinical researchers in the NICU field. On the weight of existing evidence, our understanding of swallow and respiratory physiology, and our clinical experience, we do not support the practice of feeding infants on CPAP/ HFNC.

 

Positive airway pressure (as is delivered via CPAP) works by stenting open the airway.  We know that HFNC delivers some degree of positive pressure (we just can’t usually measure how much, as the set-up of HFNC doesn’t allow us to measure pressure actually delivered to the airway each time we use it) (see Wilkinson et al, 2008).

 

We also know to swallow safely, the airway needs to close during each swallow (deglutition apnea), which is more difficult to do when there is stenting via positive pressure keeping the airway open.

 

There is also a potential for the high airflow to passively blow part of the bolus into the airway.  Additionally, there is a potential for high airflow to cause desensitization of normal airway protective mechanisms.

 

Patients who require HNFC have lung disease, and are at increased risk of swallowing impairment from this alone.  When patients are still on positive pressure support, we need to consider both their underlying respiratory disease and the fact that the intervention (CPAP/ HFNC) may in itself affect swallow safety as we evaluate their suck-swallow-breathe coordination and overall swallowing function.

 

In the NICU, most of the infants we work with will have improved respiratory functioning with growth and maturation.  However, there is a risk that their lung disease will be prolonged or worsen if they have lung injury from aspiration on top of their existing lung disease.

 

Even with specialty training and much experience, it is difficult to identify aspiration risk in infants with clinical assessment alone. More overt clinical cues include increased congestion (wet vocalizations, fremitus), or physiological changes (SpO2 desaturation, apnea, bradycardia). However, we know that a very high proportion of infants who aspirate do so ‘silently’ (Arvedson et al in their 1994 paper suggested 94% of infants who aspirate do so silently – Dr. Dodrill and her colleagues are reviewing records from their pediatric MBS service (currently over 1200 MBS per year), and believe the proportions of silent aspiration observed in their facility are similar to the original reports from the Arvedson article).

 

Hence, clinically we often cannot observe overt signs of aspiration in infants, and have to make an assessment of risk based on symptoms (e.g. prolonged transition from supplemental O2 requirements, prolonged transition to full PO feeds) or case history (multiple studies show that infants with BPD are a population at high risk of suck-swallow-breath incoordination in the NICU, and ongoing feeding difficulties throughout infancy and childhood – see many papers by Gewolb & Vice, da Costa et al 2010, Radford et al 1995, etc).

 

We have both worked alongside staff members who have historically allowed PO feeding while on CPAP/ HFNC.  Clinically, we felt that the symptoms of aspiration were often attributed to the underlying lung disease. Hence, we began using MBS to determine swallow safety in these infants. However, after finding that the vast majority were silently aspirating while feeding, we have stopped the practice of feeding any infants on CPAP or HFNC.

 

None of us want to hold a baby back from eating – if they are medically ready. We would argue that it is better to keep patients safe while they are recovering from the lung disease and still requiring CPAP/ HFNC, and work on nutritive feeding later, when they are medically appropriate.

 

During the time when they are NPO, we obviously encourage non-nutritive sucking and swaddling/ holding infants during tube feeds, to promote sucking and infant-caregiver bonding.

 

In many cases, the length of time when infants are on HFNC is only days before they can transition to LFNC, and many are on LFNC by or before their due date, so we don’t feel the potential risk justifies pushing them early.

 

Having worked for years with older infants and children (post-NICU) with feeding difficulties, we feel that the aversion that often develops following repeated aspiration (or other adverse respiratory events during feeding – like apnea and tachypnea) is much harder to overcome than any potential set-back from waiting a few days (or even weeks in rarer cases) to start PO feeds when the infant is off positive pressure support.

 

As to the Leder et al. paper that was recently published in Dysphagia and referenced in this thread of online discussion:

 

None of the infants in the Leder et al. study appear to have a direct feeding evaluation (either formal clinical assessment or instrumental assessment) to confirm safety of PO feeding.  They report on their initial criteria for determining readiness to try PO feeds, but make no mention of direct feeding evaluation, and no mention of staff training (i.e. there do not appear to have been feeding therapists involved, and there is no mention of RN/ MD staff involved having any specific training in feeding assessment or management).

 

The authors state:

Decisions to initiate oral feeding and monitor oral feeding success were made jointly by neonatology and nursing using the following criteria: 1. Stable respiratory status on 2–3 l/min of HFO2-NC; 2. Corrected gestational age 32 weeks; 3. A demonstrated pattern of steady weight gain and growth with an attained weight of 1001–1300 g; 4. Cardio-respiratory stability; 5. Neurodevelopmental maturation including alertness for oral feeding; 6. Ability to tolerate bolus feeds; 7. Non-nutritive sucking; 8.  Demonstration of hunger cues; and 9. Inability to handle oral secretions as evidenced by coughing, excessive drooling, and wet/gurgly breathing or voice [2].

 

The Leder et al. study reports that 2/3 of the NICU infants on HFNC (33/50) were not deemed safe by staff to be offered oral feeds. Of the 1/3 (17/50) who were deemed ‘safe’ by staff, it appears all continued to require tube feeds.  Insufficient data is presented to determine if the practice of offering the infants oral feeds while on HFNC benefitted them in any way (e.g. lead to them reaching PO feeds at an earlier corrected gestational age).  Data presented also do not allow us to evaluate if offering the infants oral feeds while on HFNC harmed them in any way (e.g. if it lead to them reaching full oral feeds at a later corrected gestational age, or whether there was a higher rate of any adverse respiratory events, such as aspiration, apnea +/- bradycardia events during feeds).

 

The authors state: A total of 17 of 50 (34 %) neonates requiring HFO2-NC were deemed developmentally and medically appropriate to begin oral feedings by the neonatologist and nursing. All 17 (100%) were successful with initiating oral feedings supplemented by continued enteral tube feedings.

 

Given the observational nature of this study (i.e. it was not a RCT), and the fact it was cross sectional vs longitudinal (i.e. there was no long-term follow-up), we do not believe they produced enough data to support the claim that these infants had ‘oral feeding success’ or the claim that:

 

…it is not the use of HFO2-NC per se but rather patient-specific determinants of feeding readiness and underlying medical conditions that impact decisions for oral alimentation.

 

We believe that feeding therapists play an integral role in feeding management in the NICU.  NICU feeding management is a specialty area of practice that requires advanced skills and ongoing training. We highly encourage all health care professionals involved in assessing feeding safety in this population to utilize formal clinical assessment tools (e.g. the Early Feeding Skills Assessment, by Thoyre et al) and instrumental swallow assessments to guide their practices.

 

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Memorie Gosa

Tuscaloosa, AL