There is this idea of a feeding “window” for the infants in our NICU, where PO trials ideally need to happen within this “window” or there could be longer-term feeding issues. This idea is perpetuated by nurses, physicians, and our developmental care specialist but as an SLP I am not only puzzled but can’t find any research refuting or supporting it. I think the way in which its used by other staff is that this “window” exists around 40-43 weeks and that it is important that if PO hasn’t already happened, that trials at least need to happen during this timeframe.
Does anyone have any research for or against this “window”? Or know the origin of this idea?
Unfortunately, today many of our preterm infants are being asked to feed much earlier/younger and that can readily cause more stress, unless the approach is infant-guided and not volume-driven. Today, the pressure to get infants out of the NICU often drives many care decisions, especially when it comes to PO feeding.
It’s not uncommon for neonatologists to assume that there is a window within which our preterms must “experience” PO feeding or they will “miss that critical window and never learn”. There needs to be reconsideration of that paradigm to consider instead, individualized readiness to PO. This is why.
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. NICUs were just being developed, there were no therapists as part of the neonatal team, as the need for therapy support, much less feeding support, was not well understood. Many NICU infants did not survive or did so back then with enduring developmental concerns. NICU infants, though they weren’t asked to PO feed as early back then, they eventfully were PO fed. Prior to initiating PO, the infants did not have developmental support for the system-based underpinnings to support that future PO feeding and avert maladaptive sensory, sensory-motor and oral-motor patterns that often evolved. At that same time community in Early Intervention, and even in the early 80s when I first started out, we rarely saw former preemies who had survived the NICU until they were often 4 or 5 years old. Can you even imagine? And they came with horrific stories back then, and complex maladaptive behaviors. The fragile marginal subsystems that underpinned PO feeding had been dormant all that time, and the infants developed maladaptations from motor learning environments that were not therapeutic; but the nurses in the NICU had done the best they could without therapeutic collaboration/insights, and then parents, after discharge, did the best they could without support of therapists. You can see how “not missing a window” might have been seen as the key, to avert such outcomes, when actually, it was the need to provide the right kind of environment to nurture the prerequisites, individualize care, and then further support emerging PO skills. That was then. This is now.
Today with the advent of neonatal interdisciplinary teams that include PT/OT and ST, we can better support readiness by maintaining those systems for future PO when co-morbidities safely permit. “Readiness” that is not determined based on an arbitrary date or age, but infant-guided readiness based on clinical signs/behaviors in the context of that unique infant’s GA (age at birth) and history/co-morbidities. That is the gestalt that, when considered thoughtfully, can set the stage for success, or, if not considered, create the perfect storm for risk. That gestalt benefits from neonatal care that is neuro-protective and promotes positive overcomes and recognizes safety issues inherent with some co-morbidities and clinical presentations that should suggest caution.
Concern for “missing that critical window” has led perhaps to team decisions to PO with “let’s see what happens” or “let’s let him practice”. But as a thoughtful nurse once said tome, “why do we ask them to PO when they are not ready? Practice doesn’t make perfect. Practice makes permanent.” I, of course, hugged her!
The concept that preterms must “experience” PO feeding or they will “miss that critical window and never learn” has led to the well-intentioned “pushing PO” and orders to PO on CPAP and HFNC. Many of our former preterms can learn to feed orally at later ages, once weaned in the level of respiratory support, and from my experience, do so with less stress and more safely. Amaizu (2008) reported that gestational age at birth (GA) influences the ex utero development of oral feeding skills more than PMA (post-menstrual age) at which PO is started. So the age, i.e., PMA (post-menstrual age) at which you start to offer PO is not the key to focus on. It is the bigger picture, which means individualizing readiness considerations.
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. Sadly, this is often the group that gets the most “pressure” to feed and go home. Does the team ask them to PO feed to not “miss a critical window”? Or does the team maintain their readiness with therapy support, to optimize safety and neuroprotection, by individualizing readiness?
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 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 prolonged NIPPV, CPAP and/or HFNC at those post-menstrual ages when PO feeding is typically 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. 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. Indeed, infants for whom we do not necessarily witness aspiration during a dynamic swallow study may indeed show alterations in swallowing physiology that may predispose them to airway invasion under “the right conditions” during PO feeding (changes in nipple flow, changes in position, changes in respiratory support or work of breathing at that moment, for example). The fact that NICU infants “eat” and “are fed” and “transferred volume” does not equate to “safe or neuroprotective feeding”. Ferrara and colleagues (2017, 2020) and Ferguson (2015) have contributed greatly to our understanding of this risk.
We must of course remember the physiologic stress likely to occur when the infant experiences “feeding” when the infant is not “ready”. 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 dilemma is always part of our problem-solving discussions. After 35 years as an NICU SLP, I so appreciate and always advocate for our key role in dialoguing with the team, problem-solving and focusing on safety and neuroprotection as the essential part of this practice issue which confronts every neonatal team.
I hope this is helpful.
Amaizu, N., Shulman, R. J., Schanler, R. J., & Lau, C. (2008). Maturation of oral feeding skills in preterm infants. Acta Paediatrica, 97(1), 61-67.
Dumpa, V., Kamity, R., Ferrara, L., Akerman, M., & Hanna, N. (2020). The effects of oral feeding while on nasal continuous positive airway pressure (NCPAP) in preterm infants. Journal of Perinatology, 40(6), 909-915.
Ferguson, N. F., Estis, J., Evans, K., Dagenais, P. A., & VanHangehan, J. (2015). A Retrospective Examination of Prandial Aspiration in Preterm Infants. SIG 13 Perspectives on Swallowing and Swallowing Disorders (Dysphagia), 24(4), 162-174.
Ferrara, L., Bidiwala, A., Sher, I., Pirzada, M., Barlev, D., Islam, S., … & Hanna, N. (2017). Effect of nasal continuous positive airway pressure on the pharyngeal swallow in neonates. Journal of Perinatology, 37(4), 398.