Cold Liquids Fed to Preterm Infants: Efficacy and Safety After 10 Minutes of Exposure
Cold Liquids Fed to Preterm Infants: Efficacy and Safety After 10 Minutes of Exposure
A previous study revealed that dysphagia preterm infants show statistically significant
 improvements in their swallowing mechanism when fed cold liquid barium when compared to room
 temperature liquid barium. The previous study was the first to identify these positive
 effects, although, only assessed 5 cold liquid swallows, immediately after the room
 temperature condition. This limited data set restricts the efficacy and safety of using cold
 liquids in clinical practice, emphasizing the need for further information. The present study
 aims to objectively assess the influence of cold liquid on the pharyngeal swallow mechanism
 in preterm infants with dysphagia after 10 minutes of a cold liquid feeding. The
 investigators will utilize videofluoroscopic swallow studies (VFSS) to analyze the frequency
 and severity of pharyngeal swallowing deficits during room temperature swallows and compare
 it to cold liquid swallows at various time points within a 10 minute feeding. Safety measures
 will also be obtained, such as participant axillary body temperature and gastric content
 temperature, to identify indicators for the development of cold stress.
Swallowing dysfunction, medically defined as dysphagia, commonly occurs in infants born
 prematurely due to inadequate timing and coordination of the sensorimotor sequences required
 for safe swallowing. Approximately 70% of prematurely born infants will be diagnosed with
 oral, pharyngeal and/or esophageal phase dysphagia with an inverse relationship between
 severity and gestational age at birth.(1)

 Swallowing is extremely important for the infant and child to meet the nutritional
 requirements for growth and development. When swallowing is dysfunctional, the consequences
 can be devastating for the infant, possibly resulting morbidity, with complications including
 pneumonia, respiratory disease, growth compromise or failure to thrive.(1-6) The implications
 of swallowing difficulty are, therefore, of considerable medical importance to the medical
 team working with these infants.

 A videofluoroscopic swallow study (VFSS) is a widely used assessment for the diagnosis of
 neonatal dysphagia. VFSS is a definitive investigation to objectively assess the adequacy of
 airway protection during swallowing and allows simultaneous viewing of the bolus as it passes
 through the oral, pharyngeal and esophageal stages of swallowing.(7) For infants feeding from
 a bottle, the clinician relies on the VFSS to both identify and correct the swallowing
 dysfunction. Several therapeutic techniques or modifications are used during a VFSS to
 improve swallowing safety in infants, such as various nipple flow rates,(8,9) feeding
 positions,(10) or pacing the infant's sucking bursts.(11) The most frequently used
 modification is to thicken the infant's formula or breastmilk to a thicker
 consistency,(12-14) however, thickening causes some difficulty making it an undesirable
 option for young infants treated in the neonatal intensive care unit (NICU).(15) These
 difficulties have resulted in clinicians using alternate therapeutic techniques to treat
 dysphagia neonates. One alternate technique is to feed the infant cold liquids to stimulate a
 safer swallow.(16-20)

 Original findings obtained by these investigators was the first to indicate that cold liquid
 swallows reduce airway compromise in dysphagic preterm infants when compared to room
 temperature liquid. Specifically, the occurrence of deep penetration (p=0.029), aspiration
 (0.017), mild penetration (p=0.044) and nasopharyngeal reflux (p=0.006) decreased
 significantly in the cold swallow (CS) condition when compared to the room temperature
 swallow (RTS) condition during VFSS. Similar findings are documented in adults with
 dysphagia.(21-35) These positive effects are theorized to occur due to the cold liquid
 providing the sensory receptors within the pharynx increased sensory information which
 triggers more efficient swallowing movements.(12,13,21-23)

 The original study assessed 5 cold liquid swallows, which provided important information
 regarding the immediate effects of cold liquids on the pharyngeal swallowing mechanism in
 preterm infants with dysphagia. Further information regarding the duration of these positive
 effects is necessary to prove its reliability as a modification to be used at bedside. This
 study is designed to assess the swallowing mechanism of dysphagic preterm infants after
 feeding cold liquids for 10 minutes to objectively identify any changes over time.

 In addition to the paucity of evidence regarding improved swallowing function over time, the
 safety of feeding cold liquids remains questionable in the preterm infant population. The
 greatest concern for these infants is the development of cold stress or altered digestive
 functioning due to the cold temperature of the liquid. The effects of cold stress in infants
 are observed in all body systems, including cool skin, tachypnea, respiratory distress,
 desaturation, increasing episodes of apnea and bradycardia, increased gastric residuals, and
 emesis.(36) Several older studies have assessed the effects of cold feeds in healthy term and
 healthy pre term infants, however, study populations may not be representative of todays
 preterm infant population due to significant medical advances and increased survival rates of
 extremely preterm infants.

 Holt and colleagues(37) found no difference in sleep pattern, vocalizations, motility,
 intake, feeding behavior, weight gain, temperature or regurgitation in preterm infants with a
 weight of >1,500gm, when fed cold formula. Gonzalez and colleagues(38) found no significant
 differences in axillary temperature or gastric residuals in preterm infants fed cold (0-4°C)
 verses room temperature (25°C) milk. Participants included 14 preterm infants with a
 gestational age at birth (GAB) of 28-30w, and a mean corrected gestational age of 32 weeks.
 Anderson and Berseth(39) found no differences in infants' antral or duodenal motor activity
 as assessed via manometry, as well as gastric emptying among cold (6°C), room temperature
 (24°C), or body temperature (37°C) feeding groups. This study included preterm infants with
 GAB 25-36weeks, mean birth weights 915-2,455g. Corrected gestational age of 32-36 weeks at
 the time of the study. Feedings were given in random order for 3 liquid temperatures. Across
 all temperatures they found that all infants emptied approximately one third of the bolus
 feeding by 20 minutes. And across all temperatures approximately 10-20% of the bolus feeding
 remained in their stomach 2 hours post-prandially. The authors propose that thermo-receptors
 within the gastrointestinal tract do not appear to be functional in this age group.

 Blumenthal and colleagues(40) found no statistical differences between stomach emptying rate
 in cold (0-4°C), room temperature (25°C) or body temperature (37°C) formula in 20 healthy
 preterm infants with a mean birth weight of 2.75 ± 0-18 (range 1.49-3.38) kg, and gestation
 37-7 ± 0.6 (range 34-41) weeks. They also reported that in all infants the cold feeds were
 well tolerated and produced no obvious clinical effects.

 To assess the potential risks of cold stress, each participant's body temperature will be
 obtained pre and post cold liquid exposure. To assess digestive functioning, the temperature
 of each participant's gastric contents will be obtained pre and post cold liquid exposure by
 extraction of the gastric content via a naso-gastric tube (NGT). If the child does not have a
 naso-gastric tube in place at the time of the study, the subjects will be enrolled but no
 documentation of the stomach content temperature will be obtained.
Inclusion Criteria:

 -  Infants born prematurely, as defined by birth at less than 37 weeks gestational age,
 referred for a videofluoroscopic swallow study (VFSS) due to suspected pharyngeal
 phase dysphagia.

 Exclusion Criteria:

 -  Infants born prematurely with a corrected gestational age of 43 weeks or greater.