Estimation of diaphragm depth based on waist circumference in the Thai population.

Introduction/aims: There is a potential risk of causing a pneumothorax during needle electromyography of the diaphragm. The diaphragm depth can be estimated from body mass index (BMI), but this may not be practical in bedbound patients. The objectives of this study were to formulate correlation equations to estimate diaphragm depth based on waist circumference (WC) and determine their validity.