CPAP caps are associated with head growth restriction and altered skull morphology in newborn infants

Sebastian Jacob^1,2,3*Nancy Wetzel⁴Annett Bläser¹Ulrich Herbert Thome^1*Rudolf Georg Ascherl¹

• ¹Division of Neonatology, Department of Women’s and Children’s health, University Hospital Leipzig, Leipzig, Germany
• ²Department of Pediatrics, University Hospital of Halle-Wittenberg, University Hospital in Halle, Halle, Saxony-Anhalt, Germany
• ³Institute of Infectious Diseases and Infection Control, University Hospital Jena, Jena, Thuringia, Germany
• ⁴Department of Child and Adolescnet Psychiatry, Psychosomatic Medicine and Psychotherapy, University Hospital Jena, Jena, Thuringia, Germany

Background: CPAP devices for preterm infants are commonly affixed by snug-fitting caps. Monitoring of head growth is standard-of-care in preterm infants and stagnant head growth has been associated with impaired neurodevelopmental outcome. However, a stagnant head circumference may not mean stagnant head growth since vertical head distortion has been repeatedly observed. Previously established centiles for ear-to-ear distances and head volume indices allow the evaluation of three-dimensional head growth. We hypothesized that CPAP duration may be associated with restricted head circumference gain, altered skull morphology, and possibly neurodevelopment. Patients and methods: All 4590 infants treated with CPAP on the neonatal wards of the Leipzig University Medical Center between 2009 and 2020 were included in our study. Body weight and length, occipitofrontal head circumference (OFC) as well as transvertical (vEED) and transfontanellar ear-to-ear (fEED) distances were measured repeatedly. Head eccentricity (ECC) (a measure of disproportional head growth and head volume indices (HVI) were calculated. Anthropometric data were z-transformed. 367 infants were followed up for assessment of neurodevelopmental outcome by Bayley Scales of Infant and Toddler Development (third edition). Associations between cumulative cap time and anthropometric data were assessed by unconditional growth models with linear mixed effects. Associations between head growth development and neurodevelopmental outcome were assessed by correlating individual regression slopes of anthropometric data and Bayley scores. Results: Cumulative cap time was negatively associated with z-scores of OFC (β=–1.32×10–2, p<0.005), vEED (β=–6.65×10–3, p<0.005], fEED (β=–1.05×10–3, p>0.05) and HVI (β=–1.59×10–2, p<0.005), while it was positively associated with ECC (β=5.18×10–3, p<0.005). Individual OFC z-score slopes show low correlation with cognition (R=0.07), language (R=0.06) and motor (R=0.01) Bayley scores. Individual vEED z-scores slopes show low correlation with cognition (R=-0.10), language (R=-0.08) and motor (R=-0.07) Bayley scores. Conclusion: CPAP caps are associated with vertical and horizontal head growth restriction and altered infant head morphology by increasing eccentricity. The correlation of the altered growth pattern with neurodevelopmental outcome was negligible. Our findings have clinical implications for the assessment of head growth development during CPAP therapy.