This is a practice dilemma for all NICU SLPs. The pressure to get infants out of the NICU often drives care decisions, especially when it comes to PO feeding.
Many neonatologists incorrectly assume that there is a window within which our preterms must “experience” PO feeding or they will “miss that critical window and never learn”. So, despite co-morbidities and often respiratory needs that are paramount, infants are being asked to feed. That well-intentioned paradigm is based on writings from Gesell back in the 60s that talked about a “critical window” for learning to eat. Those times were different in many ways as was the population being described. Early intervention now in NICUs to support readiness, neonatal care that is neuro-protective and promotes positive overcomes, and recognition of safety issues inherent in the complex task of PO feeding even when weaned from CPAP and HFNC clearly call for reconsideration of that paradigm, which, perhaps to a large part, underlies the thinking that leads to “pushing PO” and orders to PO on CPAP and HFNC. Many of our former preterms do indeed learn to feed orally at later ages, once weaned, and from my experience do so with much less stress and much more safely.
Advocating for safety for these infants is a critical one for SLPs in the NICU and PICU. Current NICU technology has advanced to the point that more infants are surviving and yet many are requiring extended periods of CPAP and HFNC. Many extremely preterm infants in our NICU with CLD at post-term (41 weeks PMA +) remain dependent on CPAP or HFNC. MY NICU team has had good collaborative conversations about the benefits of ST being involved to maintain a positive oral-sensory environment, promoting the oral-sensory-motor components that are the underpinnings for future PO feeding, beginning early to foreshadow for parents the swallowing, breathing and postural skills needed, and helping families also support those components, versus attempting PO feeding when the infant clearly is struggling with respiratory stability. Clearly, medical co-morbidities predispose an infant in the NICU to PO feeding problems. Multiple papers have studied that. Those infants with the greatest respiratory comorbidities, often those born < 28 weeks’ gestation and BW < 1000 grams, are most likely to require CPAP and/or HFNC at those post-menstrual ages when PO feeding is often attempted. Sick newborns may also present similar issues, secondary to their co-morbidities.
If the infant has such respiratory needs that he requires CPAP, or a HFNC, one must ask if PO feeding is really a priority for that infant at that time. The ability to reconfigure the pharynx from a respiratory tract and back to an alimentary tract with precise timing and coordination surrounding each swallow is a concern. When we look objectively in radiology during an instrumental assessment of swallowing physiology, even infants with CLD stable on RA have altered or impaired swallowing physiology as a direct result of their CLD. The bolus mis-direction and resulting aspiration we often observe is typically silent. In the adult population in the most recent information I have seen (Garon et al, 2009 Journal of Neuroscience Nursing) reported that of 2000 adults studied with a variety of co-morbid conditions, including COPD, 54.5% of those who aspirated did so silently. The data I have collected thus far for NICU infants suggests strongly to me that even the data from Arvedson et al in 1994 likely underestimated the tendency for infants to silently aspirate. In addition, her study population was not only less involved from a respiratory perspective back in 1994 than the population we see today, but it also was a population composed of not just infants. The need for an “urgent breath” often can predispose an infant with increased work of breathing to silently mis-direct the bolus into the airway during the swallow. The ability of the infant to close the glottis against the driving force of the respiratory support, while breathing with increased effort or with an increased respiratory rate, which effectively creates air hunger, and yet still maintain glottic closure throughout the duration of the swallow, would likely be precarious. Given the infant’s likelihood of baseline tachypnea and increased WOB, the dynamic adjustments of the airway surrounding the swallow are likely to be disrupted, and create uncoupling of swallowing and breathing. Without objective data on the impact of CPAP or HFNC on swallowing physiology we cannot conclude that feeding under these conditions is “safe”. Indeed, infants for whom we do not necessarily capture aspiration during a dynamic swallow study may indeed show alterations in swallowing physiology that may indeed predispose them to aspiration under “the right conditions” during PO feeding (changes in nipple flow, changes in position, changes in respiratory support for example) so it isn’t even just about aspiration but the potential impact of CPAP and HFNC on swallowing physiology. The fact that the infants “eat” and “are fed” and “transferred volume” does not equate to “safe feeding”.
We must of course consider the physiologic stress likely to occur when the infant experiences “feeding” when they still require NCPAP and or HFNC. It is highly possible the stress of trying to breathe and coordinate a swallow may lay down neural pathways that move the infant away from wanting to eat, by wiring those sensory-motor pathways that lead to current and/or future maladaptive feeding behaviors. We know that studies looking at stress in preterms have shown an association with adverse changes in brain structure on MRIs.
In the NICU seminars I teach, this body of evidence and our dilemma are always part of our problem-solving discussions. I am fortunate after 32 years in the NICU to be part of a team that is looking beyond “getting them to eat” and looking to partner with ST to guide practice while the evidence-base is emerging. NICU SLPs are in a key role to dialogue, problem-solve and focus on safety and neuroprotection as essential part of this practice issue which confronts every neonatal team.
Jim Coyle has said: “There is one rule of thumb: there is no single parameter that qualifies or disqualifies a patient for anything or that confirms or refutes risk in and of itself. It is the combination of parameters that the clinician uses to estimate risk and to form a diagnostic impression and complete a differential. That is what we teach students and trained clinicians should be emphasizing. Grab your water bottle and go for a 2-3-mile run. After 15 minutes when at your aerobic steady state and RR is up, try to take a drink of water and observe what you need to do to orchestrate the whole thing. Yet you are healthy and mature and not recovering from respiratory issues. Very illuminating.”
The dialogue needs to continue and we need measures of oral feeding that go beyond intake, and methods of assessment that capture critical variables, including objective assessment of physiology.
I hope this is helpful.