Ultrasound determination of chest wall thickness: implications for needle thoracostomy.
OBJECTIVE
Computed tomography measurements of chest wall thickness (CWT) suggest that standard-length angiocatheters (4.5 cm) may fail to decompress tension pneumothoraces. We used an alternative modality, ultrasound, to measure CWT. We correlated CWT with body mass index (BMI) and used national data to estimate the percentage of patients with CWT greater than 4.5 cm.


METHODS
This was an observational, cross-sectional study of a convenience sample. We recorded standing height, weight, and sex. We measured CWT with ultrasound at the second intercostal space, midclavicular line and at the fourth intercostal space, midaxillary line on supine subjects. We correlated BMI (weight [in kilograms]/height(2) [in square meters]) with CWT using linear regression. 95% Confidence intervals (CIs) assessed statistical significance. National Health and Nutrition Examination Survey results for 2007-2008 were combined to estimate national BMI adult measurements.


RESULTS
Of 51 subjects, 33 (65%) were male and 18 (35%) were female. Mean anterior CWT (male, 2.1 cm; CI, 1.9-2.3; female, 2.3 cm; CI, 1.7-2.7), lateral CWT (male, 2.4 cm; CI, 2.1-2.6; female, 2.5 cm; CI 2.0-2.9), and BMI (male, 27.7; CI, 26.1-29.3; female, 30.0; CI, 25.8-34.2) did not differ by sex. Lateral CWT was greater than anterior CWT (0.2 cm; CI, 0.1-0.4; P < .01). Only one subject with a BMI of 48.2 had a CWT that exceeded 4.5 cm. Using national BMI estimates, less than 1% of the US population would be expected to have CWT greater than 4.5 cm.


CONCLUSIONS
Ultrasound measurements suggest that most patients will have CWT less than 4.5 cm and that CWT may not be the source of the high failure rate of needle decompression in tension pneumothorax.
Department of Emergency Medicine, University of New Mexico, Albuquerque, NM 87131-0001, USA. romclean@salud.unm.edu
A Robb
AR
McLean
Michael E
ME
Richards
Cameron S
CS
Crandall
Jonathan L
JL
Marinaro
D000328:Adult; D001827:Body Height; D015992:Body Mass Index; D001835:Body Weight; D016001:Confidence Intervals; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D011030:Pneumothorax / Q000601:surgery; D012016:Reference Values; D012737:Sex Factors; D035441:Thoracic Wall / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D013907:Thoracostomy / Q000379:methods*; D014463:Ultrasonography; D055815:Young Adult