Computed tomography lung volume estimation to facilitate protective mechanical ventilation in a patient with achondroplasia and spina bifida

• Published in: Anaesthesia and intensive care Vol. 47; no. 5; pp. 474 - 475
• Main Authors: Mackay, Fraser C, Roth, Robyn G, van Helmond, Noud, Ben-Jacob, Talia K
• Format: Journal Article
• Language: English
• Published: London, England SAGE Publications 01.09.2019; Sage Publications Ltd
• Subjects: Achondroplasia - diagnostic imaging; Humans; Lungs; Pneumonia; Respiration, Artificial - methods; Respiratory therapy; Spina bifida; Spinal Dysraphism - diagnostic imaging; Tidal Volume; Tomography, X-Ray Computed; Ventilators
• ISSN: 0310-057X; 1448-0271
• DOI: 10.1177/0310057X19873003

Dear editor “Lung-protective” mechanical ventilation may improve mortality from acute respiratory distress syndrome (ARDS),1 but compliance with lung-protective ventilation protocols is low.2 Calculating appropriate tidal volumes based on ideal body weight (IBW) is only defined for heights >152 cm, and extending protective ventilation, for example into paediatrics, has been shown to be complex. An arterial blood gas on high-flow nasal cannula showed hypercarbic and hypoxaemic respiratory failure, and he was converted to non-invasive bilevel positive airway pressure ventilation and admitted to our intensive care unit. Lung volume was calculated with an approach that is routinely used to characterise volumes in three-dimensional structures.5 Assuming that our patient’s lungs would be functionally normal,3,4 we calculated a ratio of CT-derived volume to ARDSnet recommended tidal volume1 in a normal-height adult and applied it to our case to estimate a functionally similar tidal volume.