by perinatologija | Okt 20, 2023 | cmcrf
Dihanje je homeostatski mehanizem, ki primarno nasprotuje spremembam pO2 in pCO2 v organizmu, ki jih povzroča okolje ali organizem, in vključuje izmenjavo plinov z okoljem (ventilacijo), prenos plinov skozi alveolokapilarno pregrado (difuzija), transport plinov v krvi in celično uporabo pO2 oziroma proizvodnjo pCO2. Dihanje je uravnavano na vseh teh ravneh, čeprav uravnavanje dihanja običajno enačimo z uravnavanjem ventilacije. Ventilacijo uravnava zapleten sistem, ki vključuje generator centralnega dihalnega ritma / vzorca in integrator v podaljšani hrbtenjači in ponsu. Ta avtomatično generira bazalni ritem za krčenje dihalnih mišic, ki ga nato, glede na informacije iz kemoreceptorjev in mehanoreceptorjev ter drugih struktur, prilagaja spreminjajočim se presnovnim potrebam, mehaničnim razmeram ali vedenju. Uravnavanje ventilacije je primarno nezavedno in avtomatično, vendar lahko nanj do neke mere vplivamo tudi z voljo, kar je je mogoče med budnostjo, ko lahko z voljo celo preglasimo avtomatično uravnavanje ventilacije. Med spanjem se dražljaji budnosti in volje umaknejo, tako da je dihanje odvisno predvsem od avtomatskega uravnavanja. Uravnavanje dihanja se razvije zgodaj v fetalnem obdobju in še naprej dozoreva po rojstvu. Sistem za uravnavanje ventilacije pri dojenčkih, zlasti pri nedonošenčkih, je nezrel in sam po sebi nestabilen, kar povzroča nepravilno dihanje, pogoste apneje in periodično dihanje, zaradi česar so dojenčki bolj dovzetni za dihalno odpoved. V tem prispevku obravnavamo fiziološke osnove zrelega uravnavanja ventilacije pri odraslih in razlike pri dojenčkih.
Physiological Principles of Ventilatory Control from Infants to Adults
Breathing is a homeostatic mechanism that primarily counteracts environment- or organism-induced changes in pO2 and pCO2 in the organism, and involves exchange of gases with the environment (ventilation), transfer of gases across the alveolocapillary barrier (diffusion), transport of gases in blood, and cellular utilization or production of pO2 and pCO2, respectively. Breathing is regulated at all these levels, although breathing regulation is usually equated with the ventilatory control. Ventilation is controlled by a complex system involving a central respiratory rhythm/pattern generator and integrator in the medulla oblongata and pons, which automatically generates the basic rhythm for contraction of the respiratory muscles and then adjusts this rhythm according to changing metabolic needs, varying mechanical conditions, and a range of episodic non-ventilatory behaviours, according to the inputs from chemoreceptors, mechanoreceptors, and other structures. It is primarily involuntary and automatic and can be, to some degree, also influenced by voluntary inputs that are prominent during wakefulness and can even override automatic ventilatory control. During sleep, however, wakefulness stimuli and voluntary influences are withdrawn, so that ventilation depends predominantly on automatic control. Breathing regulation develops early in foetal life and continues to mature after birth. The infantile ventilatory control system, especially in preterm infants, is immature and inherently unstable, resulting in irregular breathing, frequent apnoeas, and periodic breathing, making infants more susceptible to respiratory failure. The article aims to review the physiological principles of mature ventilatory control in adults and the differences in infants.
Katja Pavšič, Fajko F. Bajrović
by perinatologija | Okt 20, 2023 | cmcrf
Genetski vzroki dihalnih premorov pri novorojenčkih so zelo heterogeni. Geni, vpleteni v nastanek, večinoma nosijo zapis za beljakovine, ki so vključene v razvoj lobanjskih in obraznih kosti, razvoj in funkcijo osrednjega in perifernega živčnega sistema in mišic. V diagnostičnem procesu ima pomembno vlogo zgodnja genetska obravnava in genetsko testiranje. Opredelitev genetskega vzroka dihalnih premorov lahko omogoči usmerjeno zdravljenje, boljšo napoved poteka bolezni in reproduktivno svetovanje družini.
Genetic Causes of Apnoea in the Neonate
The genetic causes of neonatal apnoea are very diverse. Genes responsible for neonatal apnoea include, among others, those encoding proteins important for craniofacial development, proteins involved in the development and function of the central and peripheral nervous systems, and muscles. Genetic testing plays a significant part in the diagnostic process, as identifying the genetic cause of apnoea can provide important information for the treatment, prognosis, and reproductive counselling for the family.
Karin Writzl
by perinatologija | Okt 20, 2023 | cmcrf
Razvoj človeških pljuč je razdeljen na pet stopenj: embrionalno, psevdoglandularno, kanalikularno, sakularno in alveolarno. Pri rasti in razvoju pljuč sodelujejo številni fizikalni, biokemični, cirkadiani in genetski dejavniki. Razvoj nevronskih povezav s pljuči, ki omogočajo ritmično dihanje, še ni razjasnjen.
Before the first breath
The development of the human lung is divided into five stages: embryonic, pseudoglandular, canalicular, saccular, and alveolar. Numerous physical, biochemical, circadian, and genetic factors are involved in the growth and development of the lung. However, the development of neural connections with the lung, which allows for rhythmic breathing, remains to be fully elucidated.
Tanja Premru-Sršen
by perinatologija | Okt 20, 2023 | cmcrf
Za novorojenčke je med spanjem značilna ranljivost dihal s posledično občasno hipoksijo. Ta je globlja pri nedonošenčkih in doseže vrh v drugem do tretjem tednu postnatalnega življenja, česar še vedno ne znamo povsem pojasniti. Sodobni pulzni oksimetri, ki vsebujejo algoritme za zavrnitev artefaktov in kratke čase povprečenja, so zelo učinkoviti pri zaznavanju kratkih desaturacij. Kljub temu pa lahko etiologijo desaturacij določimo le z bolj natančnim nadzorom, kot je srčno-dihalna poligrafija (CRP), ki razlikuje med obstrukcijskimi in centralnimi dogodki. Normalna referenčna območja za obstrukcijske in centralne dihalne premore ter indekse hipopneje so omejeni na manj kot 5 raziskav, ki so vse vključevale majhen vzorec otrok. Vse te raziskave so pokazale širok spekter normalnih vrednosti, bodisi zaradi majhnega števila vključenih otrok, združevanja otrok ob hitrih spremembah ali dejansko heterogene populacije. Definicija normalnosti je pomembna za usmerjanje vodenja otrok, predvsem tistih, ki so odpuščeni z neonatalnih enot. Raziskave CRP pri dojenčkih predstavljajo izziv, vendar potrebujemo več raziskav, da bi lahko določili referenčni spekter vrednosti. Razumevanje spektra motenj dihalnih vzorcev bi lahko predstavljalo podlago za raziskave vpliva dihalnih vzorcev na nevrokognitivne izide in prehrano.
Normal Sleep Patterns and Sleep Disturbances in Preterm and Term Neonates – the Role of Cardiorespiratory Sleep Studies
Neonates demonstrate respiratory vulnerability during sleep with resultant intermittent hypoxia. This is more profound in preterm infants and appears to peak in the second to third week of postnatal life the cause of which is unclear. Modern pulse oximeters which contain artefact rejecting algorithms and short averaging times are very effective at detecting brief desaturations. However, the aetiology of desaturations can only be determined by more detailed monitoring such as cardiorespiratory polygraphy (CRP) that discriminates between obstructive and central events. Normal reference ranges for obstructive and central apnoea and hypopnoea indices are limited to less than five studies all of which have recruited small numbers of babies. These studies all demonstrate a wide range of normal values due either to the small numbers of babies included in the studies, grouping babies together at times of rapid change, or a genuinely heterogenous population. Defining normality is important for guiding management of infants particularly those discharged from neonatal units. CRP studies in infants are challenging but more research is needed to determine reference ranges. Additionally, understanding the spectrum of respiratory pattern disturbance might support research into the impact of this on neurocognitive outcomes and nutrition.
Hazel Evans
by perinatologija | Okt 20, 2023 | cmcrf
Centralna apneja (CA) je opredeljena kot prenehanje toka zraka za vsaj 20 sekund ali za vsaj dva vdiha in povezana s prebujanjem ali desaturacijo ali bradikardijo (pri dojenčkih). CA je pogosto fiziološka, vendar je lahko povezana s številnimi etiologijami. Navadno imamo za normalnega indeks centralne apneje (CAI) do 5 epizod na uro. S starostjo povezane referenčne vrednosti, predvsem za zgodnje obdobje dojenčka, so še vedno redke in praga za prepoznavo patoloških znanj še vedno ne poznamo. V tem prispevku smo povzeli trenutna spoznanja in priporočila.
Central Breathing Disorders – Role of Polygraphy in the Diagnosis and Follow-up
Central apnoea (CA) is defined as a cessation of airflow for at least 20 seconds or the duration of 2 breaths in association with arousal or oxygen desaturation or bradycardia (in case of infants). CA is frequently a physiological finding, however, various medical aetiologies could be underlying. Generally, a central apnoea index (CAI) up to 5 episodes/hour is considered as normal. Age-related normative values, especially regarding early infancy, are still rare, and the threshold value to identify a pathological condition is still unclear. This article summarizes the current findings and recommendations.
Astrid Sonnleitner
