Spinal anaesthesia is a commonly practiced anaesthetic technique in patients  undergoing elective or emergency lower segment caesarean sections. It is a safe, cost effective and easy to perform technique which provides a denser block and so more preferred. It also avoids  the various complications of general anaesthesia like stress response, airway management, post-operative nausea and vomiting and thereby facilitates earlier resumption of feeding and mobilization. Spinal anaesthesia has a quick onset and provides satisfactory sensory and motor blockade. Administration of the appropriate choice and dose of local anaesthetic into the  subarachnoid space results in rapid onset of deep spinal anaesthesia with a greater degree of success .The rapidity of onset of spinal block is advantageous in cases where delivery of the foetus needs to be hastened  due to compromised fetal state.¹

The required dosage of effective block for LSCS has been associated with maternal arterial hypotension of 60-90% with maternal and neonatal morbidity². The haemodynamic stability and prolonged duration of analgesia were observed by injecting the local anaesthetic drug in divided doses into the subarachnoid space.^3-5

Spinal anaesthesia(SA) has rapid onset and is associated with various problems e.g. bradycardia , hypotension . Maternal hypotension may lead to decrease in uteroplacental perfusion which may result in fetal acid base imbalance, maternal nausea and vomiting and may be an important contributory factor for maternal morbidity related to regional anaesthesia.¹ Maternal hypotension and subsequent consequences are reduced to some extent by various measures like preloading or coloading of crystalloids or colloids , low dose local anaesthetic, left uterine displacement, prophylactic use of vasopressors etc but with reduction in incidence and severity of hypotension.^.

Several factors like height, weight, pregnancy and anatomical changes influence the dose of local anaesthetic drug for  its intensity and duration of spinal block. Many physiological and anatomical changes during pregnancy affect spinal anaesthesia. The hormonal and mechanical factors make pregnant women require less local anaesthetic than non-pregnant women to attain same level of spinal anaesthesia.⁶

Levobupivacaine is an effective long acting amide local anaesthetic and is an S enantiomer of racemic bupivacaine , since it does not conatin R isomer , cardiotoxicity and neurotoxicity is lesser than bupivacaine. 

In this regard, in addition to above mentioned measures, fractionated doses of local anaesthetic for spinal anaesthesia has been used to assess its effect on haemodynamic parameters in caesarean section.

In these studies, a fraction of two-third of calculated dose of local anaesthetic followed by one-third was used for spinal anaesthesia, with the incidence of hypotension during spinal anaesthesia in about 16 % patients as compared to 46% patients who had hypotension with non fractionated doses (bolus doses).

Extensive search of literature did not show any study comparing the two fractionated doses (one -third followed by two-third versus two-third followed by one-third) of local anaesthetic agent for spinal anaesthesia in the patients of caesarean section.

In the present study, haemodynamic parameters will be compared in spinal anaesthesia induced with either of two regimes of fractionated doses (one -third followed by two-third versus two-third followed by one-third ) or single bolus dose of Levobupivacaine 0.5% Heavy  in patients of caesarean section.