Emergency Medicine

NEEDLE THORACENTESIS

472 Practical Procedures

2 Diagnostic tap

(i) Sit the patient on the edge of the bed, arms folded in front of the

body and leaning forward over a bedside tray table. Expose the

whole of the back.

(ii) Percuss down the chest to confirm the upper border of the

effusion (stony dull percussion), then auscultate (decreased

breath sounds, and decreased vocal resonance).

(iii) Infiltrate local anaesthetic down to the pleura on the

posterolateral aspect of the chest wall (mid-scapular or posterior

axillary line), one to two intercostal spaces below the percussed

upper border of the effusion (but no lower than the 8th

intercostal space).

(iv) Attach a 21-gauge needle to a 20 mL syringe and insert along the

anaesthetized track, bevel up, at 90° to the surface of the skin,

working ‘just above the rib below’.

(v) Maintain constant negative pressure on the syringe by drawing

back on the plunger as the needle is advanced.

(vi) Aspirate 10–20 mL sample. Remove the needle and press firmly

over the site with a gauze swab, then apply an occlusive dressing.

(vii) Send fluid for biochemistry (protein, glucose, lactate

dehydrogenase [LDH], pH and amylase), microbiology (M,C&S

and Gram stain) and for cytology.

3 Therapeutic tap (fluid)

(i) Position and infiltrate local anaesthetic as for a diagnostic tap.

(ii) Insert a 16-gauge cannula along the anaesthetized track, bevel

up, at 90° to the surface of the skin, working ‘just above the rib

below’.

(iii) When flashback is seen, hold the stylet steady and advance the

plastic cannula as far into the thorax as it will go. Remove the

stylet while the patient holds a breath in expiration, and place

your gloved thumb over the cannula.

(iv) Secure the cannula with tape and attach the three-way tap

and 50 mL syringe, again with the patient holding a breath in

expiration (reduces the risk of a pneumothorax).

(v) Once 1000–1500 mL of fluid have been drained, remove the

cannula and press firmly over the site with a gauze swab. Apply

an occlusive dressing.

COMPLICATIONS

1 Pneumothorax.

2 Haemothorax.

3 Hypotension due to a vasovagal response.

4 Re-expansion pulmonary oedema (large volume aspirated).