Advanced Trauma Life Support guidelines recommend the use of a cannula
3 to 6 cm long to perform needle thoracocentesis for life-threatening
tension pneumothorax. The chest wall thickness in the 2nd intercostal
space, mid-clavicular line, was determined by ultrasound in 54 patien
ts aged 18 to 55 years, and ranged from 1.3 to 5.2 cm (mean 3.2 cm). I
n thirty-one patients (57 per cent) the chest-wall thickness (CWT) was
greater than 3 cm, the minimum recommended cannula length, although i
n only two (4 per cent) was it greater than 4.5 cm, the length of cann
ula commonly used in the UK. As a 3 cm cannula would fail to reach the
pleural cavity in over half of patients, we suggest that the recommen
ded shortest length be increased to 4.5 cm. Unsuccessful needle thorac
ocentesis using a 4.5 cm cannula should be followed immediately by ins
ertion of a longer cannula or a definitive chest drain. (C) 1996 Elsev
ier Science Ltd.