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Association of increased cardiothoracic ratio and intrauterine growth retardation
M E Bozynski1, F H Hanafy, R J Hernandez
1Department of Pediatrics, University of Michigan Medical Center, Ann Arbor 48109-0254.
Insights
Increased cardiothoracic ratio (CT) is strongly associated with intrauterine growth retardation (IUGR) in premature neonates. This finding highlights CT as a key indicator for identifying growth issues in vulnerable infants.
Area of Science:
- Neonatalogy
- Pediatric Cardiology
- Radiology
Background:
- Clinical observations suggest a link between elevated cardiothoracic ratio (CT) and intrauterine growth retardation (IUGR) in premature infants.
- This association requires further investigation to confirm its clinical significance.
Purpose of the Study:
- To investigate the hypothesis that an increased cardiothoracic ratio (CT) is associated with intrauterine growth retardation (IUGR) in premature neonates.
- To determine if CT ratio can serve as a predictor of IUGR in this population.
Main Methods:
- A case-control study was conducted with 23 IUGR and 55 appropriate for gestational age (AGA) premature infants (birthweight ≤ 2000 gm).
- Exclusion criteria included congenital heart disease and specific infections.
- The cardiothoracic ratio (CT) was calculated from the first chest radiograph (within 24 hours of birth) by a single radiologist unaware of growth status.
Main Results:
- IUGR infants had significantly lower mean birthweights and higher mean gestational ages compared to AGA infants.
- The mean cardiothoracic ratio (CT) was significantly higher in IUGR infants (0.57 ± 0.07) than in AGA infants (0.51 ± 0.04) (p < 0.001).
- 11 of 23 IUGR infants and only 1 of 55 AGA infants exhibited an increased CT ratio (p < 0.0001). Growth status remained the best predictor of CT even after controlling for birthweight and gestational age (p = 0.005).
Conclusions:
- There is a strong association between an increased cardiothoracic ratio (CT) and intrauterine growth retardation (IUGR) in premature infants weighing 2000 gm or less.
- Elevated CT ratio may serve as an early indicator for identifying growth-restricted premature neonates.
Abstract:
Clinical observation suggested an association between an increased cardiothoracic ratio (CT) and growth retardation (IUGR) in the premature neonate. To investigate this hypothesis, a case-control study was performed. Study subjects included 23 cases (IUGR) and 55 control (appropriate for gestational age [AGA]) premature infants with birthweights 2000 gm or less; Apgar scores greater than 5 at 5 minutes; no congenital heart disease; no polycythemia; no toxoplasmosis, rubella, cytomegalovirus, or herpes infection. In random order, the first chest radiograph of each infant (less than 24 hours) was reviewed by a single radiologist, unaware of the infant's growth status. The CT ratio was computed after measuring the widest internal width of the bony thorax and the cardiac diameter. Mean birthweight (+/- 1 SD) of the IUGR infants was 1161 +/- 289 g and of AGA infants was 1401 +/- 401 g (p less than 0.002); the mean gestational ages (+/- 1 SD) were 33.2 +/- 2.8 and 30.8 +/- 2.5 weeks (p less than 0.001). Mean CT for IUGR infants was 0.57 +/- 0.07 (+/- 1 SD) versus AGA infants, 0.51 +/- 0.04 (+/- 1 SD), p less than 0.001. When the infants were stratified by growth status and CT ratio, 11 of 23 IUGR and 1 of 55 AGA infants had an increased CT ratio p less than 0.0001. When birthweight and gestational age were covaried, growth status remained the best predictor of CT, p = 0.005. There is a strong association of increased CT and growth retardation in premature infants with birthweights 2000 gm or less.