LUMBAR PUNCTURE 



131 



soaked with lotion, and proceed to disinfect your hands. Lastly, 

 pour some alcohol on to the skin of the patient's back to wash off 

 the excess of the antiseptic. 



2. Operation — Position. — Get the patient (still lying on his left 

 side) to draw up his knees so as to flex his back somewhat, and to 

 turn partly over on to his face. 



Identify the processes of the third and fourth lumbar vertebrae, 

 and mark the centre of the space between them by means of the 

 index-finger or thumb of the left hand. If local anaesthesia is to 

 be employed freeze the skin round a point about \ inch to the 

 right of the middle line, opposite the spot marked by your 



Fig. 31. Operation of Lumbar Puncture with Patient in 



Sitting Position. 



left finger or thumb. Take the needle in the right hand, holding 

 it like a pen, and enter it at a point level with the centre of the 

 interspace, and i centimetre (a little less than i inch) to the 

 right of the middle line. Direct it forwards, slightly upwards, and 

 slightly inwards, and press it in with a steady and uniform pressure; 

 this must be applied accurately in the axis of the needle, or the 

 latter may bend and take a wrong direction. 



If the needle strikes against bone withdraw it almost completely, 

 and push it on again after changing its direction slightly. If bone 

 is again encountered it may be advisable to try again in the inter- 

 soace between the second and third processes. 



