Novel use of ultrasound-visible needle when performing thoracocentesis for low volume pleural effusion

Sir,

We would like to suggest an alternative method of performing thoracocentesis following our recent experience while attempting to perform diagnostic needle aspiration of pleural fluid in a critically ill patient.

Ultrasound assessment was performed which demonstrated a low volume effusion when scanned over the safe triangle and across the thorax. Throughout ventilation, there was only a small window of pleural fluid visible.

The British Thoracic Society, recommend using a 21-gauge hypodermic needle attached to a syringe to aspirate pleural fluid. ¹ Furthermore, it is widely accepted that aspirate should be obtained under ultrasound guidance in order to minimise the risk of pneumothorax and samples should be obtained at the time of ultrasound rather than mark an area for subsequent aspiration. Use of real-time guidance and a hands-free approach are recommended for small or loculated effusions. ²

Having attempted this technique initially, we encountered a number of issues; visualisation of the needle was poor and simultaneously positioning the probe, guiding the needle and aspirating, was technically challenging. We proceeded to use a 50-mm 22G Braun Stimuplex™ Ultra 360 needle, used in our trust for performing regional anaesthesia. Immediately, the visualisation of the needle was clearer, we had greater tactile feedback as we passed through tissues and fascial planes, and the syringe attached to the port enabled a second operator to easily aspirate the sample, ensuring both the probe and needle remained in position. Aspirating using this method was easier, as there was less tension on the needle, and retracting the plunger on the syringe did not cause movement of the needle.

Echogenic needles are far easier to visualise than non-echogenic needles and provide a greater feedback of tissue structure, which in turn can increase overall operator confidence and skill in the technique. ³

Overall, current guidance recommends the use of non-echogenic needles, whilst performing real time assessment. However, real time application of this technique can be difficult and our experience suggests that utilisation of echogenic needles (already established in practice) provides a superior alternative when accessing small or loculated effusions.