Postnatal ventilatory response to CO₂ in awake piglets.

Area of Science:

• Physiology
• Developmental Biology
• Respiratory Science

Background:

• Abnormal ventilatory responses to elevated carbon dioxide (CO₂) during postnatal development are a potential risk factor for Sudden Infant Death Syndrome (SIDS).
• A critical developmental period for ventilatory control has been previously suggested in piglets between 10 and 15 days of age.

Purpose of the Study:

• To investigate the hypothesis that the ventilatory response to hypercapnia (elevated CO₂) is attenuated in awake piglets between 10 and 15 postnatal days.
• To determine if repeated exposure to CO₂ affects the ventilatory response during early development.

Main Methods:

• Ventilatory response to 5% inspired CO₂ was measured in piglets from postnatal day 1 to 28.
• Piglets were exposed to CO₂ daily, every 3rd day, or only after postnatal day 20 to assess the impact of exposure frequency.
• Ventilation was normalized to body weight (V˙(E), ml/min/kg).

Main Results:

• Room air ventilation normalized to body weight declined with increasing postnatal age in all groups.
• The ventilatory response to 5% inspired CO₂ was present from birth and showed no significant age-dependent change between postnatal days 1 and 28 (p > 0.1).
• Neither daily nor every-3rd-day exposure to 5% inspired CO₂ altered the ventilatory response during the studied developmental period.

Conclusions:

• The previously suggested critical developmental period in piglets (10-15 days) is not characterized by an attenuated ventilatory response to 5% inspired CO₂.
• These findings indicate that changes in CO₂ responsiveness are not the primary factor explaining SIDS risk during this specific developmental window in piglets.