Letter from Victor Chelewani, Alphonso Nundwe		Dear Reader
Answer by David Bogod

Dear Sir,

When giving 1.5mls (75mg) lignocaine 5% with dextrose for Caesarean section, aiming for a block to T4 dermatome, we have noticed that patients often complain of nasal congestion after the spinal has been given. Patients receiving 2.5 mls (12.5mg) bupivacaine 0.5% with dextrose for Caesarean section aiming for the same height of block do not complain of the same symptoms of nasal congestion.

The spinal anaesthetic technique is otherwise exactly the same. A 22 or 25gauge spinal needle is inserted into the L2/3 or 3/4 interspace with the patient sitting. After the spinal needle is removed, the patient lays down flat (we do not often see the supine hypotensive syndrome and so do not routinely use left lateral tilt), 1 - 2 litres crystalloid preload, ephedrine 3-5mg as required for hypotension <100 systolic.

Could you or one of your experts please explain this finding?

Yours sincerely,
Victor Chelewani, Alphonso Nundwe
Clinical Officer Anaesthetists
Queen Elizabeth Central Hospital
Blantyre
Malawi 

Nasal congestion occuring during regional anaesthesia for Caesarean section usually indicates an excessively high block, and is caused by blockade of the cervical sympathetic outflow. Most of these patients will also demonstrate unilateral or bilateral Horner's syndrome. I suspect the reason you are seeing it when you use lignocaine but not with bupivacaine is that your dose of the former (1.5 ml) is rather generous. 5% hyperbaric lignocaine is no longer available in the UK where I practice due to concerns about neurotoxicity, but when it was in use, 1.0 - 1.2 ml given as you describe would produce a rapid and reproducible block to T4. I suspect that, if you tested your patients, you would find sensory levels in the region of C7-T1.

A couple of other thoughts spring to mind. You may not think you are seeing supine hypotension but, even if the mother's blood pressure does not fall, the fetus will still be compromised by aortic compression diminishing placental blood flow; 15 degress of left lateral tilt is easily achieved and has been proven to be beneficial. It is worthwhile testing all blocks before Caesarean section; current thinking suggests that we should aim for a block to fine touch to T5 bilaterally to minimise the risk of intra-operative pain.

David Bogod
Consultant Obstetric Anaesthetist
Nottingham City Hospital
UK 

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