1. Ask for any allergic reaction to local anesthetics
<br>2. Check proper puncture location with ultrasonography. :
:*Strive to puncture close to the inferior rib border rather than the superior one, to avoid damage to intercostal nerves and vessels. The direction of the catheter should usually be toward the basal-dorsal parts.
:*If the fluid space is wide enough, the thickness of the thoracic wall can be measured in order to subsequently perform anesthesia and catheter insertion without ultrasound guidance.