Prediction model of rhomboid major and pleura depth based on anthropometric features to decrease the risk of pneumothorax during dry needling.

Background: Although most common adverse events associated with dry needling can be considered minor, serious adverse events including induced pneumothorax cannot be excluded, and safety instructions for reducing the risk of pleura puncture are needed.

Objective: To investigate if anthropometric features can predict the rhomboid major muscle and pleura depth in a sample of healthy subjects to avoid the risk of pneumothorax during dry needling.

Methods: A diagnostic study was conducted on 59 healthy subjects (52.5% male) involving a total of 236 measurements (both sides in maximum inspiration and expiration), to calculate the accuracy of a prediction model for both pleura and rhomboid depth, as assessed with ultrasound imaging, based on sex, age, height, weight, body mass index (BMI), breathing and chest circumference. A correlation matrix and a multiple linear regression analyses were used to detect those variables contributing significantly to the variance in both locations.

Results: Men showed greater height, weight, BMI, thorax circumference and skin-to-rhomboid, rhomboid-to-pleura and skin-to-pleura distances (P < .001). Sex, BMI, and thorax circumference explained 51.5% of the variance of the rhomboid (P < .001) and 69.7% of pleura (P < .001) depth limit. In general, inserting a maximum length of 19 mm is recommended to reach the deep limit of rhomboid major decreasing the risk of passing through the pleura.

Conclusion: This study identified that gender, BMI and thorax circumference can predict both rhomboid and pleura depth, as assessed with ultrasonography, in healthy subjects. Our findings could assist clinicians in the needle length election in avoiding the risk of induced pneumothorax during dry needling.