[Pain response and measurement in infants].

Medical recognition of infant pain has been based on several complex misunderstandings. It should be no longer controversial that newborns in manner similar to other infants, have the ability to recognize painful insults and respond to them. Now it is accepted that a functional response to various stimuli by several neuropathways and both anatomic and physiologic, peripheral and central connections between sensory neurons and central nervous system occur relatively early in fetal life. Incoming painful stimuli may be influenced by several different neuromediators. It is accepted that three broad areas of pain measurement in the infant can be used. Behavioural responses, i.e. a marked change in the facial expression and crying, have been described as part of the infant response to noxious stimuli. They are related to the degree of stress and pain. The infants have the same as adults neurochemical disturbances associated with physiologic stress. Hormonal responses may perturb developmentally fragile glucose homeostasis and increase protein catabolism. The physiological consequences are changes in heart rate, respiration, blood pressure, peripheral and central vascular perfusion and various gastrointestinal functions. Because pain is associated with a risk of several physiologic changes these adverse effects should be blunted by appropriate analgesia.