Neurophysiology of pain in surgical patients

Prema Svjetskoj zdravstvenoj organizaciji (SZO) definicija boli glasi: ,,Bol je neugodno osjetno i emocionalno iskustvo povezano uz stvarnu ili moguću ozljedu tkiva ili opisom u smislu te ozljede’’. Bolni podražaj može se podijeliti prema duljini trajanja na akutnu i kroničnu bol; prema mehanizmu nastanka na organsku i psihogenu, prema uzroku na nocicepcijsku i neuropatsku bol, prema mjestu nastanka na viscelarnu i parijetalnu te prema općem uzroku na benignu i malignu. Bolni put se na osnovi anatomije neurofiziologije sastoji od četiri procesa, a to su podražaj (transdukcija), kondukcija, prijenos (transmisija), percepcija osjeta boli. Neurotransmiteri u koje ubrajamo noradrenalin i acetilkolin na simpatičnim živčanim završetcima te dopamin u SŽS-u. Drugu, veću skupinu čine prilagođivači (modulatori) transmiterske djelatnosti i to su, primjerice, histamin, glutamat i aspartat, gama-aminomaslačna kiselina (GABA) u SŽS-u. Nociceptivni bihevioralni odgovori koji se promatraju u životinja mogu biti refleksni (povlačenje), dobrovoljni i kronično bolni. Dva glavna alata korištena za procjenu boli u životinja su sustavi bodovanja boli i algezimetri.According to the World Health Organisation (WHO), pain is defined as “an unpleasant sensational and emotional experience related to real or potential tissue injury”. Painful stimuli can be classified according to their duration (acute or chronic), mechanism of onset (organic or psychogenic), cause (nociceptive or neuropathic) and location (visceral or parietal) or according to general cause (benign or malignant). Anatomy and physiology recognise four stages of pain: transduction, conduction, modulation and perception. Neurotransmitters, such as noradrenalin and acetyl-colin, are located at the synaptic nerve endings, whereas dopamine is found in the central nerve system. The second group of neurotransmitters are transmission modulators such as histamine, glutamate and aspartate in the nerve endings, and GABA and endogenous opioids in the central nervous system. The nociceptive behavioural response produced by animals can be a reflexive or voluntary response, or chronic pain. Two basic tools for pain assessment in animals are subjective evaluation of pain and algesimeters