Physiology masterclass: Extremes of age: newborn and infancy

Abstract

The first breath after birth is the most difficult in life. What happens before, during and after it?

The Consequences of Preterm Birth and Chorioamnionitis on Brainstem Respiratory Centers: Implications for Neurochemical Development and Altered Functions by Inflammation and Prostaglandins

“…Although the placenta is the site for respiratory gas exchange in utero , FBMs are detectable at 10 weeks gestational age (Boddy and Mantell, 1973 ; LoMauro and Aliverti, 2016 ). Whilst FBMs do not play a role in gas exchange, they do regulate the degree of lung liquid within the developing lungs, which is critical for normal tissue development and maturation, maintenance of intraluminal pressure and lung liquid volume, as well as the priming and entrainment of the respiratory muscles and neural circuitry for effective postnatal breathing (Harding, 1997 ; Baguma-Nibasheka et al, 2012 ; Koos and Rajaee, 2014 ).…”

“…Whilst FBMs do not play a role in gas exchange, they do regulate the degree of lung liquid within the developing lungs, which is critical for normal tissue development and maturation, maintenance of intraluminal pressure and lung liquid volume, as well as the priming and entrainment of the respiratory muscles and neural circuitry for effective postnatal breathing (Harding, 1997 ; Baguma-Nibasheka et al, 2012 ; Koos and Rajaee, 2014 ). Contractions of the diaphragm, intercostal, and laryngeal muscles carry out the physical task of FBMs, however, these muscles are under the control of the brainstem respiratory centers, which generate and coordinate breathing patterns (Dawes, 1984 ; Harding, 1997 ; Greer et al, 2006 ; LoMauro and Aliverti, 2016 ).…”

“…As in the adult, increases in the partial pressure of CO 2 (P a CO 2 ; hypercapnia) profoundly stimulate FBMs (Connors et al, 1988 ), while hypocapnia reduces FBMs (Connors et al, 1988 , 1989 ; Darnall, 2010 ). Acute hypoxia stimulates respiratory activity in adults, whereas it abolishes FBMs (Koos et al, 1986 ; LoMauro and Aliverti, 2016 ). Other factors which can influence FBMs include neurotransmitters, glucose (Natale, 1980 ), as well as inflammation and prostaglandins (Dong and Feldman, 1995 ; Herlenius et al, 1997 ; Olsson et al, 2003 ; Siljehav et al, 2014 ).…”

Respiratory muscle function in the newborn: a narrative review

“… 5 At birth, the contraction of the diaphragm develops an oesophageal pressure swing up to −70 cm H 2 O 6 and the newborn closes the glottis to maintain a positive intra-thoracic pressure and facilitate air distribution inside the lungs. 7 A study of eight infants born between 28 and 31 gestational weeks and supported by early nasal continuous positive airway pressure (nCPAP) reported that the median electrical activity of the diaphragm peak value was 19.2 μV at 20 min after birth, which decreased to 11.4 μV at 55 min of age. 8 The same study highlighted that preterm infants were capable of generating sufficient diaphragm tone during expiration to establish and maintain functional residual capacity (FRC).…”

Ontogenetic changes to bone microstructure in an archaeologically derived sample of human ribs

“…resorption spaces, secondary osteons) occurring near the pleural periosteo‐cortex and the cutaneous endocortex, and with large areas of primary lamellar bone observed in the pleural endocortex (Agnew et al ). Bone remodeling occurs early in the rib, possibly because of fetal respiratory movements that begin in the 10 th week of gestation (Burton et al ; LoMauro & Aliverti, ). Cortical porosities are greatest in infancy, decreasing to a minimum in middle adulthood, and substantially increasing in later adulthood (Sedlin et al ).…”