Clinical Management of Feedings and Complications in Preterm Infants

Complications of Preterm Birth: Medical and Developmental

• Preterm birth complications are categorized into two primary types: Medical and Developmental.

• Medical Complications: These result from immature or underdeveloped physiologic systems. Key systems affected include:

  • The pulmonary system (lungs).

  • The cardiac system (heart).

  • The digestive system (stomach).

  • The neurologic system (brain).

• Developmental Complications: These are negatively affected by the extra-uterine environment, particularly by excessive, poorly timed, and often painful stimuli.

• Infants in the neonatal intensive care unit (NICU) may miss critical periods of development due to medical treatments required for survival.

• Consequences of Missing Critical Periods:

  • Immature sucking patterns.

  • Poor coordination of the suck, swallow, and breathe sequence.

  • Increased risk for aspiration.

  • Difficulties with bottle feeding and a prolonged transition to full oral feeding.

• Observable Behaviors of Feeding Difficulty:

  • Respiratory distress.

  • Fatigue.

  • Inadequate weight gain.

  • Prolonged initial hospitalization.

  • Increased medical costs.

• Early identification and management of feeding difficulties can prevent cardiorespiratory compromise and chronic disease.

The Impact of the Environment on Neurologic Development

• The In-Utero Environment: In the womb, infants experience stimulation that is appropriate in timing, intensity, and duration. This environment facilitates optimal neurologic development and synchronized integration with other physiologic systems.

• The Extra-Uterine Environment (Preterm): Infants born prematurely experience harsh, irregular, and intense stimulation that overwhelms their systems. This disrupts the ‘wiring’ of the brain.

• Neurologic Maturity Requirements: Autonomic regulation and respiration require an intact nervous system capable of controlling the pulmonary and cardiovascular systems.

• Characteristics of the Preterm Brain:

  • Lacks neurologic complexity, leading to poor cardiorespiratory regulation.

  • Decreased velocity of neural impulses in sensory pathways of the peripheral nervous system.

  • Fewer white matter pathways to support the coordination of swallowing and respiration.

Chronology of Physiologic System Development

• Neurologic System:

  • Begins massive production of neurons at $8$ weeks gestation.

  • Significant neural growth occurs between $24$ and $37$ weeks gestation.

  • The system is not fully mature until $20$ years of age, when myelinization of the frontal lobes is complete.

• Pulmonary System:

  • Capable of supporting respiration at approximately $24$ weeks gestation.

  • Lacks surfactant at this stage, leading to risks such as Respiratory Distress Syndrome.

  • Matures around $8$ years of life.

  • Aspiration Warning: Aspiration of milk or formula during critical lung development periods causes irreversible changes in the alveoli, resulting in lifetime breathing difficulties.

• Cardiac System:

  • The heart is capable of circulating blood at $20$ weeks gestation.

  • Heart rate variability remains unstable until around $28$ weeks gestation due to cardiac immaturity.

• Digestive System:

  • Develops around $20$ weeks gestation.

  • Suck, swallow, and breathe coordination matures around $37$ weeks gestation.

  • Gastrointestinal motility matures around $40$ weeks gestation.

The Synactive Theory of Neurodevelopment

• This theory describes the hierarchical, interdependent organization of five subsystems used to describe an infant’s interaction with the environment:

  1. Autonomic System: Regulates cardiorespiratory activity and gastrointestinal peristalsis.

  2. Motor System: Governs muscle tone, movement, and posture.

  3. Organization System: Regulates the infant’s progression through stages of arousal.

  4. Attentional System: Governs response to visual and auditory stimuli during wakefulness.

  5. Regulatory System: Balances all other subsystems.

• Preterm infants must continually strive for balance across these systems. The subsystems influence each other and are influenced by the environment.

• Environmental Influence on Stability: Variations in infant behavior related to environmental stress affect energy consumption, oxygenation, calorie requirements, and stress levels.

Developmental Milestones for Successful Oral Feeding

• Successful feeding requires:

  • Maintaining attention.

  • Sustaining respiration.

  • Performing mature sucking patterns.

  • Coordinating sucking, swallowing, and breathing.

• Impact of Respiratory Difficulty:

  • Reduces energy, leading to fatigue.

  • Decreases oxygenation, leading to stress and reduced caloric intake.

  • Infants who are cyanotic (turning blue) will likely not feed well.

Mechanisms of Airway Protection

• Laryngeal Chemo Reflex (LCR):

  • Emerges at around $35$ weeks gestation.

  • Stimulated by receptors in the aryepiglottic folds that stimulate the superior laryngeal nerve.

  • Results in a swallow response, laryngeal closure, and an apneic period rather than a cough.

  • Protects term infants, but can cause life-threatening events (prolonged apnea) in preterm infants.

• Cough Reflex:

  • Develops around $44$ weeks gestation.

  • The LCR subsides as the cough reflex develops.

• Aspiration in Preterm Infants:

  • Preterm infants are predisposed to aspiration due to lack of neurologic maturation of the swallow-respiratory mechanism and the lack of a cough reflex.

  • Silent Aspiration: Aspiration occurring without overt signs like coughing.

• Clinical Markers of Aspiration (Term Infants/Children):

  • Coughing.

  • Color change.

  • Drooling.

  • Wet breathing.

  • Desaturation.

• Medical Comorbidities Linked to Aspiration:

  • Neurologic insults and injury.

  • Gastrointestinal disease.

  • Cardiac disease or illness.

  • Respiratory disease or illness.

Clinical Markers for Identification and Documentation

• Behavioral Clinical Markers (Disorganization):

  • Gulping: Audible loud bolus swallow.

  • Drooling: Loss of liquid from the mouth during nutritive sucking (often requires a cloth or napkin to catch spillage).

  • Muscle Tone Change: The infant may go limp or flaccid in response to feeding.

• Physiological Clinical Markers (Hypoventilation):

  • Apnea: Absence of breathing for approximately $20$ seconds without recovery; respiratory rate drops to $0$.

  • Bradycardia: Decrease in heart rate below $100$ beats per minute (bpm).

  • Color Change/Cyanosis: Turning blue due to lack of oxygen circulation, particularly around the mouth and eyes.

  • Desaturation: Drop in blood oxygen levels below $90\% \text{ SpO}_2$.

  • Tachypnea: Rapid breathing greater than $60$ breaths per minute (bpm).

• Disengagement and Stress Cues:

  • Shutdown: Pretending to be asleep (playing possum) to avoid the work of feeding.

  • Finger splay, arching, or limb extension (putting up ‘stop signs’).

  • Hyper-alert states or overt gaze aversion.

  • Slack jaw, sighing, yawning, or tongue thrusting.

  • Regurgitation or facial grimacing.

  • Mottled skin.

The Oral Feeding Skills (OFS) Assessment

• An objective approach to measure feeding ability in premature infants.

• Proficiency: Measures feeding skill during the first $5$ minutes to assess skill before fatigue sets in.

  • $\text{Proficiency} = \left( \frac{\text{mL consumed in first 5 minutes}}{\text{Total mL prescribed by physician}} \right) \times 100\%$

  • Low feeding skill is defined as a proficiency calculation less than $30\%$.\n* Endurance: Measures the rate of milk transfer during the entire feeding.

  • $\text{Endurance} = \frac{\text{Total mL consumed during feeding}}{\text{Total minutes taken to consume volume}}$

  • Low endurance is defined as a rate less than $1.5\, \text{mL/min}$.

• Feeding Skill Levels:

  • Level 1: Low Skill (< 30\% ) and Low Endurance (< 1.5\, \text{mL/min} ).

  • Level 2: Low Skill (< 30\% ) and High Endurance (> 1.5\, \text{mL/min} ).

  • Level 3: High Skill (> 30\% ) and Low Endurance (< 1.5\, \text{mL/min} ).

  • Level 4: High Skill (> 30\% ) and High Endurance (> 1.5\, \text{mL/min} ). No intervention usually needed.

Simulation Case Study and Documentation

• Infant History:

  • Born at $28$ weeks gestation.

  • Weight: $1260\, \text{grams}$.

  • Diagnosis: Prematurity, Patent Ductus Arteriosus (PDA), Reflux, and Necrotizing Enterocolitis (NEC).

• Feeding Performance (Calculations):

  • Physician ordered $10\, \text{mL}$.

  • Intake in first $5$ minutes: $0\, \text{mL}$.

  • Total intake: $3\, \text{mL}$ in $15$ minutes.

  • Proficiency Calculation: $\frac{0\, \text{mL}}{10\, \text{mL}} = 0\%$.

  • Endurance Calculation: $\frac{3\, \text{mL}}{15\, \text{min}} = 0.2\, \text{mL/min}$.

  • Interpretation: Skill Level 1 (Low skill and low endurance).

• Clinical Observations from Simulation:

  • Cyanosis, apnea, bradycardia, desaturation.

  • Initially flaccid/limp; later tachypneic during recovery.

• Impression Statement and Recommendations:

  • The infant exhibits difficulty bottle feeding as a result of poor feeding skill and poor endurance (Level 1).

  • Physiologic decline (apnea, bradycardia, desaturation, cyanosis) was observed during trials.

  • Action Plan: Recommend tube feeding without oral trials; referral for a feeding and swallowing evaluation to assess aspiration risk.

  • Communication: Notify the physician of physiologic events and concern for aspiration (reflux or prandial/during feeding) which may lead to respiratory illness.

Summary of Clinical Goals

• Understand the effects of preterm birth on physiologic subsystems.

• Recognize infant stress behaviors during bottle feeding.

• Modify expectations based on infant cues.

• Base clinical judgments on sound rationales (behavioral and objective assessments).

• Relate behavior back to the risks of illness and physiologic decline.