In a pregnant female, there is decreased requirement of the spinal anaesthetic agent because of all of the following except:
Ans. a. Exaggerated lumbar lordosis In a pregnant female, there is decreased requirement of the spinal anaesthetic agent because of decreased volume of sub arachnoid space, engorgement of epidural veins and increased sensitivity of the nerves to anaesthetic agent (but not due to exaggerated lumbar lordosis). Spinal Anesthesia Spinal anesthesia blocks nerve roots as they course through the subarachnoid space. The spinal subarachnoid space extends from the foramen magnum to the S2 in adults and S3 in childrendeg. Injection of local anesthetic below Ll in adults and L3 in children helps avoid direct trauma to the spinal corddeg. Spinal anesthesia is also referred to a subarachnoid block or intrathecal injection Factors affecting the Level of Spinal Anesthesia Most impoant factors Other factors Baricity of anesthetic solutionQ Age Position of the patientQ CSF volumeQ During injectionQ Curvature of the spineQ Immediately after injectionQ Drug volumeQ Drug dosageQ Intra-abdominal pressureQ Site of injectionQ Needle directionQ Patient heightQ PregnancyQ CSF volume inversely correlates with level of anesthesia. Increased intra-abdominal pressure or conditions that cause engorgement of the epidural veins, thus decreasing CSF volume, are associated with higher blocksdeg. This would include conditions such as pregnancyQ, ascites, and large abdominal tumorsQ In these clinical situations, higher levels of anesthesia are achieved with a given dose of local anesthetic than would otherwise be expected. For spinal anesthesia on a term paurient, the dosage of anesthetic can be reduced by one-third compared with a non-pregnant patientQ. Age-related decreases in CSF volume are likely responsible for the higher than expected level, paicularly with a hypobaric technique or rapid injection. During pregnancy progesterone also increases sensitivity of nerves to local anesthetics thus decreasing the doseQ.
Exaggerated lumbar lordosis
Decreased volume of sub arachnoid space
Engorgement of epidural veins
Increased sensitivity of the nerves to anaesthetic agent