EVE, intrathecal drug baricity and patient position
The interplay between the baricity of the intrathecal drug and gravity is an important determinant of the extent of subarachnoid block (31).
Whether the extent of increase in sensory level due to EVE also depends on the initial interplay between intrathecal drug baricity and patient position has not been specifically evaluated, but inferences can be drawn regarding its role.
Factors affecting the spread of the local anaesthetic solution Factor Mechanism Baricity
of the local Blocks can be better controlled with anaesthetic solution hyperbaric solutions Position of the Level of the block may change if the patient patient's position is altered Concentration of and A higher concentration produces a denser volume injected block; a larger volume produces a block over a larger area Speed of injection Rapid injection produces eddy currents within the CSF and a less predictable spread Increased abdominal Leads to engorgement of the epidural pressure veins and reduction in CSF volume
Alterations in the baricity of a solution to the extent of 0.
The effect of posture and baricity on the spread of intrathecal bupivacaine for elective cesarean delivery.
of the solution also influences intrathecal spread of local anaesthetics.
Besides the drug dose, the position of the patient at the time of injection and thereafter, together with the baricity
of the anaesthetic, are the most important factors affecting the level of subarachnoid anaesthesia (10,15).
Much new material relating to new spinal medications, dosage regimens, adjunctive agents, posture and baricity
and mechanisms of failure of neuraxial blockade is included in this textbook.
As addition of opiate to local anaesthetic solution has been shown to alter the volume, baricity
and hence spread of the solution (14,15), this technique is also less likely to modify the final block obtained as a much smaller volume is added.