Background and aims Thoracic paravertebral block (TPVB) is an established regional anaesthesia method technique. TPVB can be performed using either landmark- or ultrasound- guided techniques (UG).

Recommended patient position for the landmark-based technique is sitting straight-back position. There is however no recommended patient position for the optimal ultrasound visualization of the thoracic paravertebral space (TPVS). During ultrasound- guided TPVB, the pleura represents the deepest boundary of TPVS. Performing UG PVTB is easier when the pleura is closer to the body surface.

The aim of this study is to investigate if two different patient positions – straight vs curved back – yield different pleural depths, and if one patient position therefore should be preferred over the other during TPVS scanning.

Methods After ethic committee approval 51 healthy adult (age: 19–71) volunteers (31 females; 20 males) were included in the study. TPVS was identified bilaterally and pleura depth was measured at T2 and T7 levels in sitting straight-back (figure 1) and sitting curved-back position (figure 2), using a GE Venue™ 50 ultrasound machine. the difference in pleural depth between the two positions was statistically evaluated using Student’s paired t-test.

Results The mean difference in pleural distance was for T2 left(L) 4.1±0.4, right(R) 4.3±0.4 and for T7 (L) 3.4±0.3, (R) 4.2±0.3 mm (mean± SEM]. the results were statistically significant with p<0.0001 for each position comparing straight and curved back.

Conclusions Positioning a patient with a curved back offers a more superficial location of the pleura during TPVS ultrasound scanning.