Lumbar Epidural Pressure Research Articles

Comparison of Epidural Pressure Decrease Pattern According to Different Lumbar Epidural Approaches

Background: During lumbar epidural injection (LEI) using a midline approach, we might encounter failure of identifying the epidural space owing to an equivocal or absent loss of resistance (LOR) sensation. The reason for such absence of LOR sensation has been suggested as paucity of midline ligamentum flavum, paravertebral muscle, and cyst in the interspinous ligament of the lumbar spine. Despite its low specificity, LOR is the most commonly used method to identify the epidural space. Objectives: The purpose of this study was to analyze lumbar epidural pressure decrease patterns and identify factors contributing to this pressure decrease. Study Design: Prospective randomized trial. Setting: An interventional pain management practice in South Korea. Methods: This prospective study included 104 patients receiving LEI due to lumbar radiculopathy. A midline or paramedian approach of LEI was determined with randomization. Among various factors, gender, age, body mass index (BMI), and diagnosis were analyzed using a subgroup that included 60 cases of only a paramedian approach. Results: Grades I, II (abrupt decrease), and III (gradual decrease) were found as patterns of epidural pressure decrease. Abrupt pressure decrease was more frequently observed in the paramedian group (P < 0.001). Age, gender, BMI, and diagnosis did not show any significant difference in frequencies between abrupt and gradual pressure decrease. Limitations: We could not match LOR sensation with epidural pressure decrease shown in the monitor. Conclusions: This study demonstrates that abrupt pressure decrease occurs more frequently with the paramedian approach. However, age, gender, BMI, or diagnosis did not affect the incidence of epidural pressure decrease. Key words: Epidural, paramedian, midline, pressure decrease

Clinical application of a novel developed pressure bladder indicator in lumbar epidural puncture

Study ObjectiveA novel pressure bladder indicator was developed, and this study aimed to evaluate the clinical application of the pressure bladder indicator by measuring the epidural space pressure and bladder working pressure on patients undergoing lumbar epidural puncture. DesignRandomized, prospective, double-blinded study Patients130 patients SettingThe Second Hospital of Shandong University InterventionsIn this study, 60 patients undergoing surgical procedures under lumbar epidural anesthesia were enrolled to detect epidural pressure, and other 70 patients who were undergoing lumbar epidural anesthesia or combined spinal-epidural anesthesia were enrolled to evaluate the pressure bladder indicator. MeasurementsAfter successful breakthrough of ligamentum flavum by traditional methods, a pressure transducer was connected to an epidural needle tail and a monitor to measure the epidural pressure at L1-L5 in 60 patients. The working pressure of the bladder was also measured by a transducer. Then lumbar epidural puncture was performed with the pressure bladder indicator in other 70 patients. Main ResultsThe lumbar epidural pressure of the 60 patients was 9.8 ± 4.3 mm Hg, and the bladder working pressure of the pressure bladder indicator was 122 ± 15 mm Hg. All these 70 patients were confirmed with successful bladder indication and lumbar epidural puncture. Thus, the coincidence ratio was 100%. ConclusionsThe novel developed pressure bladder indicator was a reliable and useful technique to conduct successful lumbar epidural puncture.

Full-term pregnant women have higher lumbar epidural pressure than non-pregnant women: A preliminary report

The objective of this study was to compare the lumbar epidural pressure of full-term pregnant women with that of non-pregnant women. The epidural pressure of 20 full-term pregnant women and 15 non-pregnant women was measured during epidural needle insertion in the lateral position (T0), and at 30-s intervals following insertion (T1–T3), after the patient was turned supine (T4–T6), and after local anaesthetic injection (T7–T9). Results showed that the average epidural pressures following epidural insertion in the lateral position (average of T1–T3), in the supine position (average of T4–T6), and after local anaesthetic injection (average of T7–T9) were all significantly higher in the pregnant women compared with those who were not pregnant (p= 0.0293, 0.0109 and 0.0309, respectively). Epidural pressures increased significantly after women were turned supine (p < 0.001). Average epidural pressures were positive for all time points, T0–T9. It was concluded that the epidural pressure in the pregnant women was higher than in those who were not pregnant, both in the lateral and the supine position.

Obese parturients and the incidence of postdural puncture headache after unintentional dural puncture

6 Obese Parturients and the Incidence of Postdural Puncture Headache after Unintentional Dural Puncture Abstract Type: Original Research Feyce Peralta, M.D.1; Nicole Higgins, M.D.1; Laurie A. Chalifoux, M.D.1; Christian Stevens, M.D.1; Elizabeth Sanchez, M.D.2; Robert McCarthy, Ph.D.1 Northwestern University Feinberg School of Medicine1; Loyola University2Type: Original Research Feyce Peralta, M.D.1; Nicole Higgins, M.D.1; Laurie A. Chalifoux, M.D.1; Christian Stevens, M.D.1; Elizabeth Sanchez, M.D.2; Robert McCarthy, Ph.D.1 Northwestern University Feinberg School of Medicine1; Loyola University2 Background: An inverse relationship between body mass index (BMI) and postdural puncture headache (PDPH) incidence after unintentional dural puncture (UDP) has been suggested despite a lack of peer reviewed evidence. The proposed mechanism is based on the knowledge that lumbar epidural pressure is increased during term pregnancy while CSF pressure remains unchanged.1,2 It has also been shown that obese patients have decreased CSF volume compared to lean individuals.3 These findings suggest that a decreased intrathecal-epidural pressure gradient, Resulting in less CSF leak through the dural rent, may explain a lower incidence of PDPH. We hypothesized that parturients with a BMI>35 kg/m2 have a lower incidence of PDPH than those with BMI 35 kg/m2). The primary outcome was incidence of PDPH. Groups were compared using a chisquared statistic. Post hoc comparisons were made using the Bonferroni Method. P 35 group (P 35.4 Therefore, when managing these parturients, one can consider the placement of intrathecal catheters for labor analgesia/anesthesia.

Effect of airway pressure on lumbar epidural pressure during positive pressure ventilation

BackgroundThe purpose of this study was to measure lumbar epidural pressure (EP) during the insertion of a Tuohy needle under general anesthesia and to evaluate the influence of airway pressure on EP.MethodsLumbar EP was measured directly through a Tuohy needle during intermittent positive pressure ventilation in fifteen patients. Mean and peak EP were recorded after peak inspiratory pressures (PIP) of 0, 15, and 25 cmH2O.ResultsAll measured lumbar EPs were positive, with the pressure increasing during inspiration and decreasing during expiration. Median EP was 6.0 mmHg (interquartile range, 4.0-8.0) at 0 cmH2O of PIP, 6.5 mmHg (4.5-8.5) at 15 cmH2O, and 8.5 mmHg (6.0-10.5) at 25 cmH2O, increasing significantly at 15 cm H2O PIP, and further increasing at 25 cmH2O (P < 0.001).ConclusionsWe demonstrate the influence of increased airway pressure on lumbar EP measured directly through a Tuohy needle. Lumbar EPs were positive, and increasing PIP levels significantly increased lumbar EP.

Effect of Postural Change on Lumbar Epidural Pressure in Cattle

Effect of Postural Change on Lumbar Epidural Pressure in Cattle

How Changing Lumbar Epidural Pressure Affects the Distribution of Local Anesthetics and the Level of Spinal Anesthesia

Background: More than 20 factors including increased intra-abdominal pressure, as in term pregnancy or in patients with ascites, may alter spinal anesthetic block height unexpectedly. The object of this study was to observe the change of spinal anesthetic block height following the change of direct lumbar epidural pressure. Methods: Forty orthopedic patients (ASA physical status I or II) scheduled for spinal anesthesia with bupivacaine utilizing a combined spinal epidural set were divided into two groups randomly; Group C (control, n = 20) and Group S (saline, n = 20) Group S was injected with 10 ml saline to increase epidural pressure via an epidural needle after subarachnoid injection of bupivacaine. The change of epidural pressure was observed in the saline group and then the level of sensory block 5, 10, and 15 minutes after bupivacaine injection was measured in both groups. Statistical analysis was done using the Student's t-test. Results: There were significant changes in sensory block level between the two groups (P

Epidural anesthesia and acutely increased intracranial pressure. Lumbar epidural space hydrodynamics in a porcine model.

The effects of epidural injection on intracranial pressure (ICP), lumbar epidural pressure, cerebral blood flow (CBF), and spinal cord blood flow (SCBF) were studied after acutely increased ICP in swine. Twenty pigs, anesthetized with isoflurane and mechanically ventilated to maintain normocarbia, had two Tuohy needles placed in the lumbar epidural space. The ICP, lumbar epidural pressure, heart rate, mean arterial pressure, and central venous pressure were monitored. All animals had a Fogarty catheter placed in the parietal epidural space. Six pigs were randomized to a normal ICP group (group N) and eight pigs to an increased ICP group by inflation of the Fogarty catheter balloon (group R). Each pig had 0.33 ml.kg-1 of 2.0% carbonated lidocaine injected over 20 s via an epidural needle placed at L3. The ICP and lumbar epidural pressure were then monitored continuously for 30 min. Pressure-time data were fit to traditional compartmental models. Epidural elastance and resistance were calculated using a derivation of the Windkessel theory. An additional six pigs had ICP elevated as in group R and CBF and SCBF measured using radioactive microspheres at five time periods: baseline, 0-60 s, 100-160 s, 200-260 s, and at 30 min after epidural injection. The animals did not differ with respect to heart rate, central venous pressure, or mean arterial pressure at baseline. The ICP was 10 +/- 2 mmHg in group N, and 24 +/- 2 mmHg after balloon inflation in group R. After epidural injection, peak ICP was significantly greater in group R (76 +/- 22 vs. 54 +/- 17 mmHg) but not different by 30 min (17 +/- 5 vs. 11 +/- 1 mmHg). Epidural elastance in group N was 8.3 +/- 3.1 mmHg.ml-1 and 12.8 +/- 3.0 mmHg.ml-1 in group R (P = 0.045). Epidural resistance was 1,330 +/- 590 mmHg.s.ml-1 in group N and 2,220 +/- 600 mmHg.s.ml-1 in group R (P = 0.038). The CBF and SCBF were less than 10% of baseline during the 0- to 60-s time period after epidural injection. Thereafter, CBF and SCBF did not differ from baseline values. In this porcine model, epidural injection increased ICP. With increased ICP at baseline, more pronounced increases in ICP followed epidural injection. With increased baseline ICP, both epidural elastance and resistance increased compared with controls. The CBF and SCBF were markedly reduced immediately after local anesthetic injection into the epidural space.

Estimation of cerebrospinal fluid pressure via lumbar epidural space by equilibration method.

By introducing water into the lumbar epidural space from a vertically held tube under gravity, we measured lumbar epidural pressure (EDP) when the water meniscus no longer declined. In principle, the pressure of either side of dura mater had become equal at this time which is referred to as the equilibrium point. EDP measured in this way was consistently 1-3 mmHg lower than lumbar cerebrospinal fluid pressure (CSFP) not only immediately after the equilibrium point, but also for 5 min after the equilibrium point had been reached. Both EDP and CSFP responded sensitively to the manipulations of CSFP during this period. We suggest that this method may provide a means to continuously monitor CSFP by EDP.

Experimental investigation of lumbar epidural pressure measurement.

To evaluate the usefulness of lumbar intraspinal epidural pressure (ISEDP) measurements for the estimation of intracranial pressure, we studied the relationship between ISEDP and intracranial epidural pressure (ICEDP) in 25 adult mongrel dogs. ICEDP and ISEDP were measured simultaneously with Gaeltec catheter-tip pressure transducers placed in the parietal epidural space and in the lumbar epidural space. Groups 1 and 2 dogs served as normal cerebrospinal fluid condition models. Group 1 received sequential steady-state normal saline infusions (0.5, 1.0, and 1.5 ml/min) into the cisterna magna. ISEDP and ICEDP measurements exhibited a linear correlation, and ISEDP was 80 to 90% of ICEDP at any pressure level. There was no significant difference in the pressure curves obtained at the different infusion rates. Group 2 dogs were subjected to rapid pressure changes by a cisternal bolus injection. Although compliance calculated from the change in ISEDP was slightly greater than that from ICEDP at resting pressure, the compliance calculated from both ISEDP and ICEDP decreased at 20 and 30 mm Hg of ICEDP and the values became almost equivalent. Groups 3 and 4 dogs were mild and severe experimental subarachnoid models, respectively. The ISEDP and ICEDP measurements also showed a linear correlation; however, ISEDP was about 70% of ICEDP in Group 3 and about 50% of ICEDP in Group 4. Although there are varying degrees of discrepancy between ISEDP and ICEDP in the normal or subnormal pressure range and in the presence of severe spinal block, our findings suggest that ISEDP measurements can be used to estimate intracranial pressure in a clinical practice.

Analysis of human epidural pressures.

During performance of epidural injection, entry into the epidural space has traditionally been determined by identification of negative pressure to the advancing needle by indirect means such as hanging drop; loss of resistance to air, saline, or water; or use of a MacIntosh balloon. Confusion in the literature regarding entry pressures versus postentry (baseline) pressures and zero reference pressure was noted. Baseline epidural pressure changes were examined using a closed system zeroed to the dorsal spine during and after injection of local anesthetics in 39 patients referred to the Pain Treatment Center, located at SUNY Health Science Center, Syracuse, New York, for epidural injections. The course of epidural pressure changes after injection and the temporal relation of epidural pressure waves to the arterial and venous wave forms were examined. In contrast to previous investigations, subatmospheric pressure was found in the epidural space in only one patient. Baseline pressure for all patients was 7.7 +/- 3.9 mmHg. There were significant differences in baseline pressure in patients who had undergone back surgery compared with patients who had not undergone such surgery: 11.8 +/- 3.4 as opposed to 7.0 +/- 3.5 mmHg, respectively (p less than 0.005). Three minutes after a 2-ml injection of local anesthetic into the epidural space, the pressure returned to baseline. This contrasted to the effects of a 6-ml injection, which resulted in the pressure remaining above baseline after 3 minutes. The epidural pressure wave forms more closely paralleled the radial artery wave form than the central venous pressure. Lumbar epidural pressure is greater than atmospheric pressure when referenced to zero at the dorsal spine level.

The Usefulness of Lumbar Epidural Pressure as an Index of Intracranial Pressure

The reliability of lumbar intraspinal epidural pressure (ISEDP) as an index of intracranial pressure was investigated in seven patients with high intracranial pressure following neurosurgery. ISEDP and intracranial epidural pressure (ICEDP) were measured simultaneously, the latter by the conventional method. ISEDP was measured with a Gaeltec catheter-tip pressure transducer placed percutaneously in the lumbar epidural space via Touhy's needle. In five of seven patients, the ISEDP value was consistently 70 to 100% of the ICEDP value. In all patients, ISEDP always fluctuated in parallel with ICEDP, and the time courses of both were quite similar in response not only to normal cardiac pulsation but also to various manipulations, such as neck compression, coughing, breath holding, mannitol administration, and compression at the cranial defect. In one patient with communicating hydrocephalus following subarachnoid hemorrhage, the relationship between ISEDP and cerebrospinal fluid (CSF) pressure was studied. Upon gradual withdrawal of CSF, ISEDP decreased in parallel with CSF pressure until the latter reached 8 mmHg. Below 8 mmHg CSF pressure, ISEDP did not correlate with CSF pressure. This phenomenon was attributed to slackness of the dural sac due to lowering of CSF pressure, which severed contact between the spinal dural theca and the sensor. Although the discrepancy between ISEDP and ICEDP was prominent in some patients, especially those with low intracranial pressure or blockage of the subarachnoid space, in this study ISEDP reliably reflected ICEDP. The results suggest that ISEDP measurement is useful in monitoring intracranial pressure in patients with increased intracranial pressure. Also, the procedure is simple and relatively noninvasive.