Theodore Dassios1, Paul Dixon2, Ann Hickey1, Sotirios Fouzas3, Anne Greenough4,5. 1. Neonatal Intensive Care Centre, King's College Hospital NHS Foundation Trust, London, United Kingdom. 2. Individual Consultant, London, United Kingdom. 3. Paediatric Respiratory Unit, University Hospital of Patras, Patras, Greece. 4. Division of Asthma, Allergy and Lung Biology, MRC & Asthma UK Centre in Allergic Mechanisms of Asthma, King's College London, London, United Kingdom. 5. NIHR Biomedical Centre at Guy's and St Thomas NHS Foundation Trust and King's College London, United Kingdom.
Abstract
OBJECTIVES: To compare the anatomical (VD-Ana ) and alveolar dead space (VD-Alv ) in term and prematurely born infants and identify the clinical determinants of those indices. WORKING HYPOTHESIS: VD-Ana and VD-Alv will be higher in prematurely born compared to term born infants. STUDY DESIGN: Retrospective analysis of data collected at King's College Hospital NHS Foundation Trust, London, UK. PATIENT SELECTION: Fifty-six infants (11 term, 45 preterm) were studied at a median age of 8 (IQR 2-33) days. METHODOLOGY: VD-Ana was determined using Fowler's method of volumetric capnography. VD-Alv was determined by subtracting VD-Ana from the physiological dead space which was determined by the Bohr-Enghoff equation. VD-Ana and VD-Alv were related to body weight at the time of study. RESULTS: The median VD-Ana /kg was higher in prematurely born infants [3.7 (IQR: 3.0-4.5) mL/kg] compared to term infants [2.4 (IQR: 1.9-2.9) mL/kg, adjusted P = 0.001]. The median VD-Alv /kg was not higher in prematurely born infants [0.3 (IQR: 0.1-0.5)] compared to term infants [0.1 (IQR: 0.0-0.2) mL/kg] after adjusting for differences in respiratory rate and days of ventilation (P = 0.482). VD-Ana /kg was related to postmenstrual age (r = -0.388, P < 0.001), birth weight (r = -0.397, P < 0.001), and weight at measurement (r = -0.476, P < 0.001). VD-Alv /kg was related to postmenstrual age (r = -0.254, P < 0.001), birth weight (r = -0.291, P = 0.002), and weight at measurement (r = -0.281, P = 0.003) and related to days of ventilation (r = 0.194, P = 0.044). CONCLUSIONS: VD-Ana /kg and VD-Alv /kg increased with decreasing weight and gestation. VD-Alv was higher in infants that have undergone prolonged mechanical ventilation.
OBJECTIVES: To compare the anatomical (VD-Ana ) and alveolar dead space (VD-Alv ) in term and prematurely born infants and identify the clinical determinants of those indices. WORKING HYPOTHESIS: VD-Ana and VD-Alv will be higher in prematurely born compared to term born infants. STUDY DESIGN: Retrospective analysis of data collected at King's College Hospital NHS Foundation Trust, London, UK. PATIENT SELECTION: Fifty-six infants (11 term, 45 preterm) were studied at a median age of 8 (IQR 2-33) days. METHODOLOGY: VD-Ana was determined using Fowler's method of volumetric capnography. VD-Alv was determined by subtracting VD-Ana from the physiological dead space which was determined by the Bohr-Enghoff equation. VD-Ana and VD-Alv were related to body weight at the time of study. RESULTS: The median VD-Ana /kg was higher in prematurely born infants [3.7 (IQR: 3.0-4.5) mL/kg] compared to term infants [2.4 (IQR: 1.9-2.9) mL/kg, adjusted P = 0.001]. The median VD-Alv /kg was not higher in prematurely born infants [0.3 (IQR: 0.1-0.5)] compared to term infants [0.1 (IQR: 0.0-0.2) mL/kg] after adjusting for differences in respiratory rate and days of ventilation (P = 0.482). VD-Ana /kg was related to postmenstrual age (r = -0.388, P < 0.001), birth weight (r = -0.397, P < 0.001), and weight at measurement (r = -0.476, P < 0.001). VD-Alv /kg was related to postmenstrual age (r = -0.254, P < 0.001), birth weight (r = -0.291, P = 0.002), and weight at measurement (r = -0.281, P = 0.003) and related to days of ventilation (r = 0.194, P = 0.044). CONCLUSIONS: VD-Ana /kg and VD-Alv /kg increased with decreasing weight and gestation. VD-Alv was higher in infants that have undergone prolonged mechanical ventilation.