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Relationship between severe obesity and depth to the cricothyroid membrane in third-trimester non-labouring parturients: a prospective observational study
Methods: In this prospective observational study, two anaesthetists performed airway ultrasonography on 15 severely obese (BMI >45 kg m-2) and 15 normal-weight (BMI ≤25 kg m-2) parturients in the third trimester, using the transverse and longitudinal planes, sniffing and extended head positions, and nil and firm transducer pressures. The primary outcome was CTM depth (millimetres) measured in the transverse plane with the head extended and nil transducer pressure. Secondary outcomes included CTM depth measurements using other factor configurations. Intra-class correlation coefficients assessed the inter-observer reliability.
Results: CTM depth measured in the transverse plane with head extended and nil transducer pressure was significantly greater in severely obese parturients, mean 18.0 mm (95% confidence interval 16.3-19.8), vs 10.6 mm (8.81-12.4) in non-obese (P<0.001); mean difference 7.4 mm (4.9-9.9; P<0.001). CTM depths were increased in the severely obese group regardless of scanning plane, head and neck position, or transducer pressure (all P<0.001). There was excellent inter-observer reliability.
Conclusions: Cricothyroid membrane depth is significantly increased in severely obese vs normal-weight parturients independently of scanning plane, head and neck position, or transducer pressure.
History
Publication title
British Journal of AnaesthesiaVolume
120Issue
5Pagination
1033-1039ISSN
0007-0912Department/School
Tasmanian School of MedicinePublisher
Oxford Univ PressPlace of publication
Great Clarendon St, Oxford, England, Ox2 6DpRights statement
© 2018 British Journal of Anaesthesia. Published by Elsevier Ltd. All rights reserved.Repository Status
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