Diaphragm Dimensions of the Healthy Preterm Infant

Abstract

ABSTRACT. Background. The diaphragm is the major inspiratory muscle in the neonate; however, human neonatal diaphragm development has not been extensively studied. We hypothesized that diaphragm thickness (t di ) would be positively related to postmenstrual age (PMA), body weight, body length, head circumference, and nutritional intake.Objectives. To evaluate the evolution of diaphragm growth and motion in the healthy, preterm infant.Methods. We used ultrasound to measure t di at the zone of apposition to the rib cage and diaphragm excursion (e di ) during inspiration. Thirty-four stable, preterm infants (16 males and 18 females) between 26 and 37 weeks' PMA were studied during quiet sleep at weekly intervals until the time of discharge or transfer from the neonatal intensive care unit. All infants were clinically stable and not receiving ventilatory support.Results. We found that 1) t di increased from 1.2 ؎ 0.1 to 1.7 ؎ 0.05 mm between 26 to 28 and 35 to 37 weeks' PMA; 2) t di was positively correlated with PMA (r ‫؍‬ 0.40), body weight (r ‫؍‬ 0.52), body length (r ‫؍‬ 0.53), and head circumference (0.49), but not with postnatal nutritional intake (r ‫؍‬ 0.09); and 3) e di decreased with increasing PMA.Conclusions. Our findings suggest that diaphragm development in premature infants scales with body dimensions. We speculate that the increase in t di with age is likely attributable to increased diaphragm muscle mass, and the reduced e di with age may be resulting from a reduction in chest wall compliance. Pediatrics 2001; 108(5). URL: http://www.pediatrics.org/cgi/content/full/ 108/5/e91; diaphragm, development, ultrasound.ABBREVIATIONS. t di , diaphragm thickness; FRC, functional residual capacity; ⌬t di , change in diaphragm thickness; PMA, postmenstrual age; BL, body length, HC, head circumference; NI, nutritional intake; GA, gestational age; e di , diaphragm dome excursion; BW, body weight.

Diaphragm dimensions of the healthy term infant

“…The latter finding may be due to the small range of gestational ages among our subjects (GA between 37 and 40 wk). The absence of any correlation between t di and GA in term infants is in contrast to our finding of a significant correlation between t di and GA (between 26 and 37 wk) in premature infants (20).…”

“…In support of this notion, we found that t di scaled with BW to the power of 0.57, i.e. t di $ BW 0.57 , which is similar to the relationship between t di and BW that we previously determined in preterm infants (t di $ BW 0.61 ) (postmenstrual age, 26-37 wk) (20).…”

“…The noninvasive feature of ultrasonography makes it well suited for the study of neonatal diaphragm (12,19,20). Our findings that 1) t di at end-expiration is positively associated with BW and BL and 2) calculated diaphragm strength is independent of length and weight are similar to what we previously found in adults.…”

Diaphragm ultrasound as a predictor of successful extubation from mechanical ventilation

“…We found that the ROC for tdi end-expiration was less than that for Δtdi% alone (0.79 for Δtdi% and 0.61 for tdi end-expiration). The failure of this model to improve extubation predictions may be related to the variability of tdi among individuals24 25 or the presence of ventilator induced diaphragm atrophy in some but not other patients 3. We reasoned that the product of Δtdi% and V T may be a better predictor of extubation success than Δtdi% alone.…”

Critical diaphragm failure in sudden infant death syndrome

“…Assuming the same relative organ proportions as in the adult, a normal neonate weighing 3000 g would have a diaphragm that weighs approximately 12 g and is approximately 2 mm thick (26). Indeed, roughly similar dimensions are observed in preterm infants weighing between 1260 g and 2100 g who have diaphragms that are between 1.09 (±0.08) and 1.74 (±0.04) mm thick (27). An increase in diaphragm size correlates directly with inspiratory force (28), and full-term infants reach adult levels of Pdi max at approximately 6 months of age (25).…”