Hemodynamic changes during endotracheal suctioning are mediated by increased autonomic activity

Area of Science:

• Neonatal Physiology
• Autonomic Nervous System Regulation
• Cardiovascular Hemodynamics

Background:

• Endotracheal suctioning in intubated infants causes significant cardiovascular and cerebral hemodynamic changes.
• The precise mechanisms, especially the role of the autonomic nervous system, remain incompletely understood.

Purpose of the Study:

• To investigate the role of the autonomic nervous system in regulating physiological changes during endotracheal suctioning.
• To determine the effects of endotracheal suctioning on heart rate (HR), mean arterial blood pressure (MABP), and renal sympathetic nerve activity (RSNA) in newborn lambs.

Main Methods:

• Studied nine ventilated newborn lambs, assessing cardiovascular and neural responses to endotracheal suctioning.
• Utilized interventions including vagotomy and atropine administration to elucidate autonomic pathways.
• Compared responses during interrupted ventilation versus a closed suction system with maintained ventilation.

Main Results:

• Suctioning caused significant decreases in HR and increases in MABP and RSNA.
• Atropine blocked the HR response, while vagotomy abolished all observed changes.
• Even with maintained ventilation, suctioning increased MABP and RSNA and decreased HR.

Conclusions:

• Suctioning stimulates sympathoexcitatory receptors in large airways with afferent fibers in the vagus nerve.
• Increased sympathetic activity leads to peripheral vasoconstriction and elevated MABP.
• The heart rate response is primarily mediated by parasympathetic activity, as indicated by atropine's effect.