Posture and epidural block in pregnant women at term

Upper and lower limb blood flow was measured in 4 fullterm pregnant women in the left lateral and supine positions before and after epidural block. Radial artery mean blood pressure was recorded in 6 full term pregnant women under the same conditions. Before epidural block there was a much greater reduction in lower limb blood flow (39-1%) than in upper limb blood flow (13-5%) when women moved from the lateral to the supine position; this was probably the result of aortic compression. Mean radial artery pressure increased slightly by 4-6% due to maternal overcompensation in the upper part of the body. After epidural block, patients in the lateral position had a mean rise in lower limb blood flow of 25% and a reduction in upper limb blood flow of 37-2%. The mean arterial pressure remained unchanged. In the supine position there was no further reduction of upper limb blood flow; this was accompanied on average by a 9% fall in mean radial arterial pressure indicating decompensation in the mother. The leg blood flow fell less, 26-9% than before epidural block. In the supine position, a greater flow to the legs, associated with a decreased mean arterial pressure, would be expected to lead to a diminution in placental perfusion, which is the probable mechanism for foetal decompensation. Therefore the supine position should be avoided with an epidural block. In other patients it would be wise not to rely upon maternal compensatory mechanisms.     

Comparison of spread of epidural anesthesia in pregnant and nonpregnant women

Using a standardized epidural anesthetic technic, we compared levels of sensory anesthesia in patients undergoing cesarean section and in nonpregnant women undergoing elective surgery. When equal volumes of local anesthetic solutions were injected (either 15 ml or 20 ml of 0.75% bupivacaine without epinephrine), there was no statistically significant difference in sensory levels in pregnant and nonpregnant patients.     

The distribution of solutions in the epidural space

In 21 patients the distribution within the epidural space of epidurally injected 99mTc-DTPA was assessed. The gamma emissions from the epidural space were measured externally with the patients in supine position by use of a gamma camera. The recordings over the patient's back were stored in digital computer for 60 min. The results were as follows; 1) The spread of the radionuclide was mainly to cephalad direction, and seldom crossed the L5 level to sacral region. 2) The solution injected in the epidural space would distribute to less resistant compartments and the spread depends on the power of injection, negative pressure in the high epidural space and capillary pressure. 3) The elimination half-life of the injected radionuclide was between 1 to 17 min depending on the region in the epidural space. 4) The solution injected in the epidural space may penetrate dura mater at the ink cuff area and local anesthetic agents may affect the spinal nerve roots in the subarachnoid space rather than at the extra-dural space. 5) With continuous infusion technique the diffusion and penetration of the local agent through the dura mater are facilitated and more profound anesthetic effects would be expected. In clinical practice the utilization of the continuous infusion method should be considered along with the bolus injection.     

Liposarcoma in the epidural space

STUDY DESIGN: A patient with myxoid liposarcoma in the lumbar epidural space is reported. OBJECTIVE: The subject was treated with marginal resection and posterior instrumentation. SUMMARY OF THE BACKGROUND DATA: Liposarcoma is a malignant tumor of the soft tissues. It is commonly seen in the thigh. Lumbar extradural space is an unusual localization. Two cases have been reported with this localization in the literature. METHODS: The authors have treated a female patient with myxoid liposarcoma in lumbar extradural space with marginal resection and posterior instrumentation. RESULTS: The histopathologic examination showed myxoid liposarcoma. Two cases have been reported in the literature. CONCLUSION: Myxoid liposarcoma is a malignant tumor of the soft tissues. The extradural tumor was probably originated from the epidural fat tissue. Although wide resection is advised in the thigh localization, extradural localization of the tumor can be treated with marginal resection if there is no invasion to the surrounding tissue.     

Anatomy of the epidural space

Despite the importance of anatomical knowledge in the safe and effective conduct of thoraco-lumbar epidural anaesthesia there are widespread misunderstandings about the detailed anatomy of this complex region. Current textbooks and teaching continue to propagate misleading information.     

Cannulation of the epidural space

A group of 685 obstetric patients were randomly allocated to have their epidural block performed using either a 16-gauge or an 18-gauge Tuohy needle. Bleeding was noted from needle or catheter trauma in 18% of patients and it proved impossible to insert the catheter in 3%. The majority of mothers experienced little discomfort during the procedure but 2% found insertion to be very uncomfortable. There was no significant difference in the complication rate, ease of use, or patient discomfort between the 18- or 16-gauge needles. Epidural analgesia, although safe, is not without hazard. It may be difficult to perform and may, rarely, cause considerable discomfort.