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Biomedical subjects

J L Shah

Publications and source records attributed to J L Shah.

17 recordsLinked to original sources
PubMed1994

Positive lumbar extradural space pressure.

Specially selected soft Macintosh balloon indicators were attached to needles during five extradural and five spinal punctures. When the needle point entered the extradural space, the mean balloon pressure decreased suddenly from 24.9 (range 14-37) to 12.3 (10-16) mm Hg in the five extradural punctures and from 22.3 (17-28) to 13.7 (10-17) mm Hg in the five spinal punctures. In the five spinal punctures, the balloon pressure did not alter when the needle was advanced from the extradural to the subarachnoid space. Contrary to expectation, none of the balloons deflated when the needle point entered the extradural or subarachnoid spaces. The balloon pressure varied rhythmically in synchrony with respiration and cardiac pulsations. The final balloon pressure, extradural space pressure and subarachnoid pressure were equal. The results suggest that the extradural pressure is positive and of the same magnitude as the prevailing lumbar cerebrospinal fluid pressure. Jugular venous compression, ventilation with carbon dioxide and positive end-expiratory pressure (PEEP) produce a rapid increase in cerebrospinal fluid (CSF) pressure. These stimuli also produced a measurable increase in the lumbar extradural pressure. Jugular venous compression increased the mean lumbar extradural pressure by 6.8 (3-10) mm Hg and ventilation with carbon dioxide increased it by 10 (5-12.5) mm Hg. PEEP values of 5, 10, 15 and 20 cm H2O produced an immediate increase in extradural pressure of 1-2 mm Hg for every 5 cm H2O of PEEP. The lumbar extradural pressure increased rapidly with stimuli known to increase CSF pressure. Changes in spinal CSF pressure may be detected by measuring extradural pressure.

Adult↗
PubMed1993

Epidural pressure and postdural puncture headache in the parturient.

Forty patients in whom the dura had been punctured accidentally and 10 patients who had received spinal anaesthesia required epidural blood patching for relief of severe postdural puncture headache (PDPH). Before injecting blood, the epidural pressure was measured, using an epidural catheter as a manometer. Mean epidural pressure in the left lateral position was 6.4 cm H(2)O (range 0.5-12 cm H(2)O). Epidural pressure was not related to the size of needle hole or prophylactic infusion of saline into the epidural space. In 5 patients with inadvertent dural tap, there was a statistically significant decrease (P<0.02) in epidural pressure from 14.9 cm H(2)O (range 11-22 cm H(2)O) before PDPH to 6.9 cm H(2)O (range 5-8.5 cm H(2)O) when they developed PDPH. The benefits of performing an epidural blood patch through a catheter placed in the epidural space are discussed.

Journal Article↗
PubMed1993

Epidural pressure during infusion of saline in the parturient.

Epidural pressure was measured in 17 post-partum patients who were receiving prophylactic infusion of saline into the epidural space after an inadvertent dural tap. During the infusion, the mean (+/-SD) epidural pressure was 19.1 (+/-4.3) cm H(2)O. Four patients complained of severe interscapular pain during the infusion. The epidural pressure in these patients was higher than 24 cm H(2)O. Prophylactic infusion of saline into the epidural space failed to prevent postdural puncture headache in 10 patients.

Journal Article↗
PubMed1991

Severe headache following an epidural 'top-up'.

Half an hour after a normal delivery under epidural analgesia, a patient was given a top-up of 10 ml 0.25% bupivacaine for suture of a small vaginal tear. The patient developed severe headache, nausea and vomiting immediately after the top-up. Initially these symptoms were attributed to a complication of epidural analgesia. However, a raised epidural pressure led to a diagnosis of hypertensive encephalopathy.

Journal Article↗
PubMed1985

Resin injection studies of the lumbar extradural space.

Two resin injection studies of the lumbar extradural space were performed to elucidate its size and shape. To counteract the lack of cerebrospinal fluid pressure in the cadaver, the subarachnoid space was filled with water. In group 1, the extradural injection of resin caused an immediate increase in subarachnoid pressure. The casts produced varied in thickness, but were situated predominantly in the dorsomedial and dorsolateral regions of the spinal canal. Thin anterior spread occurred in 40% of cases. In group 2, resin was injected to the subarachnoid space before the extradural injection of dyed resin. The resulting extradural casts were thinner than in group 1, but the distribution of resin was similar. The problems of interpreting resin casts are discussed in relation to the results obtained, with reasons for suggesting that the extradural space is only potential.

Aged↗
PubMed1985

Epidural blood patch using a catheter. Diagnosis of an unrecognised dural tap.

Twenty five patients were treated with an epidural blood patch for persistent headache, following a known or suspected dural puncture. Fifteen to 20 ml blood was injected into the epidural space through a catheter inserted one space away from the dural puncture. The catheter technique was useful in confirming the clinical diagnosis of previously unrecognised dural tap in six patients with severe headache. It was possible to perform the blood patch single-handed.

Adolescent↗
PubMed1984

Effect of posture on extradural pressure.

Extradural pressure was measured in the lateral and the supine positions in three groups of patients using the extradural catheter as a manometer. The groups consisted of 20 pregnant patients at or near term, 10 patients in the period after childbirth and 10 male surgical patients. In every patient, the extradural pressure in the supine position was greater than that in the lateral position. The mean extradural pressures in the lateral and the supine positions were similar in the three groups. It is suggested that the difference between the extradural pressures in the lateral and the supine positions is physiological and occurs irrespective of vena caval compression. Extradural pressure changes are probably the result of postural changes in the cerebrospinal fluid (CSF) pressure. The influence of CSF pressure on extradural pressure was confirmed further by measuring the extradural pressure in the prone position in five pregnant patients.

Adolescent↗
PubMed1981

Influence of cerebrospinal fluid on epidural pressure.

The pressure in the epidural space was measured with a water manometer in 40 women receiving elective epidural for pain relief in labour, and in three patients who were undergoing lumbar puncture. Injection of a small volume of fluid in the epidural space produced a positive pressure in all subjects, with a mean of 14 cmH2O (range 6.5-20 cmH2O). Pressure varied with posture, respiration, cough and jugular venous compression. The variations in pressure agreed closely with those reported for cerebrospinal fluid (CSF) pressure. It is suggested that in the lumbar region the dura fills the vertebral canal and is both compressible and expansile. When fluid is injected into the epidural space, the dura acts as a movable membrane and pressures on either side of it tend to equalise. Measurement of epidural pressure may provide a less traumatic way of estimating CSF pressure than traditional methods.

Adolescent↗