Changes in intracranial pressure and epidural pulse waveform following cold injury

Summary Using anaesthetized spontaneously breathing cats, intracranial pressure (ICP) was monitored for twenty hours following the insult of cold injury; simultaneous recordings were also made of cerebral blood flow (CBF), epidural pulse waveform (EDP-WF), and systemic arterial pressure (SAP). Results could be divided into two groups depending on whether or not ICP exceeded 30 mmHg. In group one, in which marked increase in ICP including occasional episodes of pressure waves were observed, an initial increase in CBF and the changes in EDP-WF from polyphasic to monotonous at about 20 mmHg were characteristic. On the other hand, in group two, ICP never exceeded 30 mmHg, CBF slightly and continuously decreased and EDP-WF was polyphasic throughout the course. There were no significant differences in trends in SAP, in the extent of spread of oedema and in water content of the white matter between both groups. Therefore, the amount of cerebral blood volume (CBV) due to cerebral vasodilatation was considered to account for the further increase in ICP. Moreover, changes in EDP-WF were regarded as a useful indicator in predicting the trends in ICP since these changes could be observed in a relatively lower pressure range prior to a marked increase in ICP.     

Spread of epidural analgesia following a constant pressure injection

(1) The spread of epidural analgesia following injection of 15ml of 2% mepivacaine was 17.3 ± 0.6, 14.3 ± 0.4, and 13.3 ± 0.7 spinal segments in cervical, thoracic, and lumbar epidural analgesia, respectively. The patients age showed significant correlation with the spread of epidural analgesia in cervical (r = 0.5776, p < 0.001), thoracic (r = 0.3758, p < 0.01), and lumbar area (r = 0.8195, p < 0.001). The spread of cervical epidural analgesia was more caudad than cephalad (p < 0.05), but in lumbar epidural analgesia it was more cephalad than caudad (p < 0.05). There was no difference between the cephalad and caudad spread in thoracic epidural analgesia.(2) The epidural pressure immediately after injection of 15ml of 2% mepivacaine into the lumbar epidural space at a constant pressure (80mmHg) correlated to the patients age (r = –0.5714, p < 0.001) and the spread of analgesia (r = –0.3904, p < 0.05). The lower epidural pressure associated with higher age, the wider spread of analgesia. There was no significant correlation between the residual pressure at 60 seconds and the age or the spread of analgesia.(Hirabayashi Y et al.: Spread of epidural analgesia following a constant pressure injection: an investigation of relationships between locus of injection, epidural pressure and spread of analgesia. J Anesth 1: 44–50, 1987)     

Complications related to thoracic epidural analgesia: a prospective study in 1071 surgical patients

In a prospective study, the complications of 1071 patients scheduled for thoracic epidural catheterization for postoperative analgesia (TEA) were studied. All catheters were inserted preoperatively between segment Th 2/3 and Th 11/12 under local anesthesia. Balanced anesthesia with endotracheal intubation and TEA were combined. Postoperatively 389 patients (36.9%) were monitored on a normal surgical ward. Buprenorphine, 0.15 to 0.3 mg, and if needed bupivacaine 0.375% 3–5 ml h^-1 were given epidurally. Primary perforation of the dura occurred in 13 patients (1.23%). Radicular pain syndromes were observed in six patients (0.56%). In one patient (0.09%) respiratory depression was seen in close connection with the epidural administration of 0.3 mg buprenorphine. Although 116 patients (10.83%) showed one abnormal clotting parameter but no clinical signs of hemorrhage, there was no complication related to this group. No persisting neurological sequelae caused by the thoracic epidural catheters were found. In conclusion, continuous TEA with buprenorphine for postoperative pain relief after major abdominal surgery is a safe method without too high a risk of catheter-related or drug-induced complications, even on a normal surgical ward and when one clotting parameter is abnormal.     

The effect of spinal hyperbaric bupivacaine–fentanyl or hyperbaric bupivacaine on uterine tone and fetal heart rate in labouring women: a randomised controlled study

The mechanism for fetal heart rate abnormalities following spinal opioids remains controversial. We evaluated uterine tone, using an intra‐uterine pressure catheter, and fetal heart rate abnormalities in 30 women in spontaneous labour with cervical dilation of 3–5 cm having combined spinal‐epidural analgesia. Women were randomly assigned to receive a spinal with 2.0 mg hyperbaric bupivacaine plus 15 μg fentanyl, or 2.5 mg hyperbaric bupivacaine. The primary outcome measure was an increase > 10 mmHg in baseline uterine tone in the 30‐min period following spinal injection. Only three (20%) women who had a bupivacaine–fentanyl spinal showed a > 10 mmHg increase in baseline tone vs. none who had bupivacaine (p = 0.63). The mean (SD) baseline uterine tone after the spinal injection was 13.3 (7.0) mmHg in the bupivacaine–fentanyl group and 7.7 (2.5) mmHg in the bupivacaine group (p = 0.01). Seven (47%) in the bupivacaine–fentanyl group showed new onset fetal heart rate changes during the 30‐min period after the spinal, compared with two (13%) in the bupivacaine group (p = 0.04); however, these were transient and responded to intra‐uterine resuscitation. Pain scores, sensory and motor block as well as neonatal outcomes were comparable between the groups. We found that raised baseline uterine tone was not more frequent when using bupivacaine–fentanyl rather than bupivacaine in the spinal component of combined spinal‐epidural, although absolute values of baseline tone were higher, and fetal heart rate changes more frequent, in the former group.     

Quantitative assessment of motor block in labouring women receiving epidural analgesia

The assessment of motor block associated with epidural analgesia is traditionally performed using the modified Bromage Score. However, it is a qualitative and quantitative measurement of both spread and intensity of motor block in the lower limbs, and it has been adapted from Bromage's original use as an assessment of the adequacy of epidural anaesthesia for abdominal surgery. A number of quantitative assessment methods exist but these are either laboratory based and/or impracticable in the clinical situation of labour. We therefore set out to devise a quantitative assessment method which would be easy to use and acceptable to labouring women receiving epidural analgesia. A force transducer was modified to enable power of hip adduction to be assessed quantitatively before and after epidural analgesia was established. These results were compared with the modified Bromage Scale and an extended scale which further subdivided the scores between 0 and 1. Our results show that there is a large variation in the quantitative measurement of motor block (as measured by adductor strength) that may not be detected by the sole use of the modified Bromage Score. We suggest that future studies to assess motor block in the clinical setting use an additional quantitative method of assessment.     

Epidural pressure and its relation to spread of epidural analgesia

The relationships between the epidural pressures following the injection of local anesthetic solution and the spread of epidural analgesia were investigated. In 46 patients, 15ml of 2% mepivacaine was injected into the lumbar epidural space at a constant rate (1ml/sec) using an electropowered syringe pump. Injection pressures and residual pressures were recorded and the spread of analgesia to pinprick was assessed. The changes of the epidural pressures during and following the injection of a volume of local anesthetic solution in old subjects were significantly smaller than those in young subjects (P < 0.05). The spread of analgesia closely correlated with the epidural pressures during and following the injection of local anesthetic solution. The most close correlation was found between the epidural pressure immediately after the completion of injection and the spread of analgesia (r = –0.5659, P < 0.001). In conclusion, the lower the terminal injection pressure and the residual pressures associated with higher age, the wider the spread of epidural analgesia.(Hirabayashi Y, Matsuda I, Inoue S et al.: Epidural pressure and its relation to spread of epidural analgesia. J Anesth 1: 168–172, 1987)     

Randomized study of intravenous fluid preload before epidural analgesia during labour

We performed a randomized controlled trial of the effect ofintravenous fluid preload on maternal hypotension and fetalheart rate (FHR) changes in labour after the first epiduralinjection. Group 1 (49 women) received 1 litre of crystalloidpreload. Group 2 (46 women) received no preload. No statisticallysignificant difference was shown between the two groups foreither of the outcomes. Hypotension was found in three womenin group 1 and five in group 2 (P=0.4). Deterioration in FHRpattern was found in four women in group 1 and 11 in group 2(P=0.08). This study has not shown a significant increase inthe incidence of hypotension when intravenous preload is omittedbefore epidural analgesia using a low concentration of bupivacaineduring labour. Because of the clinical importance of the differencein the rate of FHR deterioration between the two groups, wecontinue to administer preload for high-risk cases. Br J Anaesth 2000; 85: 311–3 Footnotes ^* Correspondingauthor     

Survey of epidural analgesia management in general intensive care units in England

BACKGROUND: The management of epidural analgesia is controversial. Many intensive care unit (ICU) patients may benefit from this form of analgesia but have one or more contraindications to its use. Sepsis, coagulopathy, insertion in a sedated, ventilated patient, and lack of consent are common problems in ICU patients. Little has been published to help guide practice in this area. I wished to establish the current practice of the management of epidural analgesia in general ICUs in England when relative or absolute contraindications occur, in order to determine the current standard of care for placement and use of epidural analgesia in ICU patients. METHODS: A postal questionnaire survey of the management of epidural analgesia in critically ill patients was sent to the named clinical director of all (216) general ICUs in England. RESULTS: Responses were received from 159 (75%) units: 89% of responding units use epidural analgesia but only 51(32%) have a written policy covering its use. Anesthetists or intensivists with an anesthetic background sited all epidural catheters; 68% of units would not site an epidural in a patient with positive blood cultures; but only 52% considered culture negative sepsis (systemic signs of sepsis with no organism isolated) to be a contraindication. Neither lack of consent nor the need for anticoagulation after the catheter had been sited were considered contraindications to inserting an epidural catheter by the majority of respondents. Although 71% of the units would remove an epidural catheter if a patient developed positive blood cultures after it had been sited, the majority of the ICUs did not consider culture negative sepsis and the need for anticoagulation contraindications to maintain a previously sited epidural. CONCLUSIONS: Practice varied considerably with little consensus. Although all the respondents use epidural analgesia in critically ill patients, the indications and contraindications to epidural analgesia remain controversial, and further research is required to help define the role of epidural analgesia in this high-risk group.     

Efficacy of postoperative epidural analgesia in adolescent scoliosis surgery: a meta‐analysis

Background: Scoliosis surgery is one of the most painful operations performed. Postoperative pain management has been historically based on the use of intravenous opioids. Many of the adolescents who undergo these procedures are at increased risk for opioid‐related side effects because of underlying medical problems. Epidural analgesia has been demonstrated to provide superior pain control with fewer side effects for chest and abdominal surgery in children as well as adults. We aim to analyze the available literature for sufficient evidence to allow recommendations regarding the use of epidural analgesia with parenteral opioids vs. intravenous opioids only. Search strategy: Public Medline and the Cochrane database were searched (1966‐10/2008) using scoliosis‐related and epidural analgesia‐related terms. In Medline, the intersection of these results was combined with Phases 1 and 2 of a highly sensitive search strategy recommended for identifying randomized trials. No limits were used in any search. Additionally, professional journals and proceedings of meetings were screened, and nationally recognized experts in the field of pediatric pain management were asked for further sources of data. Selection criteria: Randomized, controlled trials comparing the use of a continuous infusion of epidural local anesthetics plus intravenous opioids vs. intravenous opioids only for postoperative pain management in adolescent scoliosis repair were eligible for inclusion in the meta‐analysis. All studies had to include at least the primary outcome of interest, postoperative pain scores. Data collection and analysis: After the development of a data collection and extraction form, two independent reviewers extracted all. No data conflicts were encountered. Data were analyzed with Review Manager when possible, significance for difference between relative rates between groups was analyzed by chi‐square tests. Main results: Average pain scores were lower in the epidural group than no epidural group at 24, 48 and 72 h after surgery. Pain scores (0–100) were lower on all first three postoperative days (POD) in the epidural group: ?15.2 on POD1, ?10.1 on POD2 and ?11.5 on POD3. Differences were significant in the summary analysis for all 3 days (P < 0.05). Authors’ Conclusion: Epidural analgesia is beneficial to patients in terms of improving pain control and reducing side effects. The influence on respiratory depression, length of stay in the intensive care unit, or mortality is not available in the literature at this time.     

A survey of epidural analgesia for labour in the United Kingdom

A postal survey of obstetric units throughout the UK was conducted to obtain information about the provision of epidural analgesia for labour. Ninety per cent of units offered a 24-h epidural service and the average epidural rate was 24%. The most commonly administered epidural test dose was 3 ml of bupivacaine 0.5% and bupivacaine 0. 25% was most often used as the initial epidural top-up. Continuous infusions of low-dose bupivacaine and opioid mixtures were the most popular method of maintenance epidural analgesia. Twenty-four per cent of units offered combined spinal-epidural analgesia in addition to standard epidural analgesia. Midwives played a prominent role in the administration of epidural bolus top-ups and also in the assessment and maintenance of continuous epidural infusions.     

Intrathecal catheterisation after observed accidental dural puncture in labouring women: update of a meta-analysis and a trial-sequential analysis

BackgroundOur meta-analysis from 2013 showed that inserting a catheter intrathecally after an observed accidental dural puncture can reduce the need for epidural blood patch in labouring women requesting epidural analgesia. We updated our conventional meta-analysis and added a trial-sequential analysis (TSA).MethodsA systematic literature search was conducted to identify studies that compared inserting the catheter intrathecally with an epidural catheter re-site or with no intervention. The extracted data were pooled and the risk ratio (RR) and 95% confidence interval (95%CI) for the incidence of post-dural puncture headache (PDPH) was calculated, using the random effects model. A contour-enhanced funnel plot was constructed. A TSA was performed and the cumulative Z score, monitoring and futility boundaries were constructed.ResultsOur search identified 13 studies, reporting on 1653 patients, with a low risk of bias. The RR for the incidence of PDPH was 0.82 (95%CI 0.71 to 0.95) and the RR for the need for epidural blood patch was 0.62 (95%CI 0.49 to 0.79); heterogeneity of both analyses was high. The TSA showed that the monitoring or futility boundaries were not crossed, indicating insufficient data to exclude a type I error of statistical analysis. Contour-enhanced funnel plots were symmetric, suggesting no publication bias.ConclusionsConventional meta-analyses showed for the first time that intrathecal catheterisation can reduce the incidence of PDPH. However, TSA did not corroborate this finding. Despite increasing use in clinical practice there is no firm evidence on which to base a definite conclusion.     

Evaluation of the efficacy of elastic compression stockings in prevention of hypotension during epidural anaesthesia for elective caesarean section

The ability of graduated compression elastic stockings to prevent hypotension during elective epidural caesarean section was evaluated. Twenty women were randomly assigned to two groups of ten, one group being fitted with the stockings. The incidence and degree of hypotension were the same in both groups. Graduated compression elastic stockings are of no benefit in reducing the incidence of maternal hypotension during caesarean section.     

压力波形监测在硬膜外麻醉穿刺置管中的研究进展

在传统盲探穿刺的基础上,近年来提出一种新的压力波形监测方法用于硬膜外麻醉。相比较于临床普遍采用的阻力消失法以及超声引导、计算机断层扫描、介入造影等新兴的辅助硬膜外麻醉的穿刺方法,大量研究表明压力波形监测方法可作为硬膜外麻醉穿刺成功的客观指征,可全程实时监测硬膜外麻醉过程,安全可靠,简便实用。文章回顾压力波形监测方法在硬...     

Audit of epidural analgesia in children undergoing thoracotomy for decortication of empyema

Background: Uncertainty remains over the risk of epidural space infectionafter neuraxial blockade in the presence of systemic sepsis.For many years, we have provided epidural analgesia to childrenundergoing thoracotomy for the decortication of parapneumonicempyemas. Following recent publications asserting that epiduralanalgesia is absolutely contraindicated in this situation, weaudited our management. The purpose of this audit was to documentthe effectiveness and the incidence of complications after epiduralinsertion in children with active sepsis from empyemas. Methods: This is a retrospective single-centre audit over a 10-yr period. Results: Forty-six epidurals were performed in children with empyema,and three children were treated with systemic opioids. We foundno infective complications of the epidural space or insertionsites. The epidurals provided excellent analgesia. The incidenceof moderate–severe pain was 18%, and 2% for severe painin the first 24 h after surgery. Minor complications of epiduralanalgesia were uncommon. Two children receiving systemic opioidsfor pain relief suffered respiratory complications, one of whichresulted in a prolonged admission to the intensive care unit. Conclusions: Epidural analgesia provides excellent pain relief after thoracotomyin children with empyema, with a low complication rate. Untilevidence to the contrary emerges, it remains our technique ofchoice for thoracotomy, even in the presence of empyema.     

Retrospective evaluation of continuous epidural infusion for postoperative pain in children

BACKGROUND: The safety and efficacy of postoperative epidural analgesia (EDA) in children are not well documented in larger series of patients given routine postoperative care. The aims of this study were to evaluate the efficacy of pain relief, determine the incidence and type of complications during the entire period of epidural pain treatment in children, and assess the factors affecting efficacy METHODS: Children treated postoperatively with an EDA infusion during the period 18 September 1994 to 1 January 1999 were studied. Data regarding the age, gender, efficacy of analgesia, duration of epidural infusion, types of side-effects and complications, reasons for discontinuation, and types and duration of surgery were collected daily by the Acute Pain Treatment Service. The sensory dermatomal level of the surgical incision site was included retrospectively. RESULTS: Five hundred and eighteen epidural infusions were given to 476 children. Pain relief was rated as 'good' at 76% of visits. There were no major complications or sequelae. Thirty-seven per cent of the epidural infusions were prematurely discontinued, and 21% were discontinued because of unsatisfactory analgesia. Factors related to a higher percentage of unsatisfactory function were surgical incision site located above the umbilicus, gastroenterologic surgery, protracted surgery and age. Age and duration of surgery were significantly related to unsatisfactory function. CONCLUSION: This study shows that continuous epidural infusion for postoperative pain was satisfactory in most cases, and that no major side-effects or complications occurred in children nursed on regular wards. The early recognition of unsatisfactory function of an EDA is important for a child's well being.     

Effects of thoracic epidural analgesia on lower urinary tract function in women

Aims: The need for an indwelling transurethral catheter in patients with postoperative thoracic epidural analgesia (TEA) is a matter of controversy. Subjective observations are ambivalent and the literature addressing this issue is scarce. As segmental blockade can be achieved with epidural analgesia, we hypothesized that analgesia within segments T4–T11 has no or minimal influence on lower urinary tract function. Thus, we evaluated the effect of TEA on lower urinary tract function by urodynamic studies. Methods: In 13 women with no preoperative lower urinary tract symptoms undergoing open kidney surgery by lumbotomy under TEA, we prospectively assessed changes in urodynamic parameters the day before and 2–3 days after surgery with the patients under TEA. Results: Before versus during TEA, there was a significant increase in postvoid residual (median, 5 ml vs. 220 ml, P < 0.001) and a significant decrease in maximum detrusor pressure (median, 23 cmH₂O vs. 5 cmH₂O, P = 0.001), detrusor pressure at maximum flow rate (median, 18 cmH₂O vs. 5 cmH₂O, P = 0.001), maximum flow rate (median, 12 ml/sec vs. 3 ml/sec, P < 0.001), and voided volume (median, 250 ml vs. 40 ml, P < 0.001). In addition, maximum urethral closure pressure at rest decreased significantly under TEA from median 75 cmH₂O to 56 cmH₂O (P = 0.002). Bladder sensation, maximum cystometric capacity, compliance, and functional profile length at rest were not influenced by TEA. Conclusions: TEA has a significant effect on bladder emptying with clinically relevant postvoid residual (PVR) necessitating (indwelling or intermittent) catheterization or monitoring of PVR. Neurourol. Urodyn. 30:121–125, 2011. © 2010 Wiley‐Liss, Inc.     

A comparison of different methods of lubrication of glass syringes used to identify the epidural space

Measurement of loss of resistance in glass syringes is a method widely used to locate the epidural space in epidural anaesthesia. Static and dynamic forces were measured under four experimental conditions in new glass syringes: unpolished, dry; polished, dry; unpolished, saline lubricated; and polished, saline lubricated. The unpolished saline lubricated syringes had a mean (SD) static force of 53.18 (15.0) g and dynamic force of 40.88 (15.2) g. These values were significantly greater than for polished dry syringes where the values were 5.27 (2.1) g and 4.38 (0.94) g, respectively. The results show that the least amount of resistance to plunger movement is obtained by dry polishing glass syringes.     

Ten ml bupivacaine 0.125% with 12.5 μg epinephrine is a reliable epidural test dose to detect inadvertent intravascular injection in obstetric patients. A double-blind study

A double-blind study was designed in order to determine the specificity and sensitivity of an epidural test dose to detect inadvertent intravenous injection in obstetric patients undergoing epidural analgesia. Forty unselected obstetric patients were given an intravenous injection of 10 ml bupivacaine 0.125% with 12.5 micrograms epinephrine (test dose) or 10 ml normal physiologic saline. The maternal heart rate was monitored by the direct ECG mode of a fetal monitor and registered simultaneously with the tocogram. The primary investigator was blinded to the solution he injected into an antecubital vein. After the injection was given, he recorded his judgment of which solution he had administered. Eight other anesthesiologists made similar judgments on the basis of the recordings plus various levels of additional information (presence or absence of epidural analgesia, time of injection, subjective signs and symptoms). In contrast to the primary investigator, the blood pressure values were not given to them. For the primary investigator, the specificity of the test dose was 100% and the sensitivity 97.5%. The judgments of the 8 other anesthesiologists resulted in an excellent specificity (99.1%) and a good sensitivity (91.9% with information on time of injection and subjective signs and symptoms). The better performance of the primary investigator is probably due to the availability of blood pressure data.