| Measurement of Epidural Pressure. |
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Jae Kyu Cheun, Jin Mo Kim, Sae Yune Kim, Sang Mok Lee |
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Department of Anesthesiology, Keimyung University School of Medicine, Taegu, Korea. |
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| Abstract |
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The epidural space is located along the entire spinal column hetween the dural mater and the external dural (periosteal) layer. It contains fat, connective tissue and numerous vessels, primarily veins. It is known that epidural pressure is negative. Negative intrathoracic pressure is thus transfered via the paravertebral spaces to the thoracic epidural spaces and to a diminishing extent to the cervical and lumbar regions. The spread of the anesthetic solution within the epidural spacea is variable according to the patient's physical characteristics such as age, arteriosclerosis according to the patients physical character-sitics such as age, arteriosclerosis, pregnancy, venous circulation and extradural fat. Other factors are under the direct control of the anesthesiologist such as positioning the patient, choosing the site of epidural puncture, orientation of the needle bevel and determining the speed of injection, volume and concentration of anesthetic solution. The epidural pressure (initial negative pr flexion pr., pr. after 10ml lidocaine injection) was measured at the lumbar 3-4 interspace by the hanging drop method. The results were summarized as follows: 1) The negative pressure was meassured in 70 cases and was observed in 95.7 percent. The lowest value was -21 cm. of water in one case and no negative pressures were observed in 2 cases.
2) The pressures after 10 ml injection exhibited three successive components: the peak, the descent and the residual values which were scattered from the injection and were observed more frequently in patients under the age of 50. A slower rate of descent and higher residual pressures were found in older patients. 3) The relationship between height, weight and epidural pressure was not observed. 4) In older patients it was observed that epidural pressures were pulsated along with the heart beats and were moved up and down with the respiratory movement. |
| Key Words:
Epidural pressure; Initial negative pressure; Flexion negative pressure; Volume pressure; Residual pressure; Residual value |
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