W. Gogarten

Regional anaesthesia and antithrombotic agents: recommendations of the European Society of Anaesthesiology

Background and objectives Performing neuraxial anaesthesia in patients receiving antithrombotic drugs is controversial due to the increased risk of spinal epidural haematoma. Strict adherence to the recommended time intervals between the administration of anticoagulants, neuraxial blockade and the removal of catheters is thought to improve patient safety and reduce the risk of haematoma. Appropriate guidelines have been prepared by a number of national societies of anaesthesiologists, but they do not have universal acceptance. The introduction of new anticoagulants together with recent reports of stent thrombosis in patients with perioperative cessation of antiplatelet drugs have considerably broadened the issue and made revision necessary. To overcome deficiencies in content and applicability, the European Society of Anaesthesiology has taken the initiative to provide current and comprehensive guidelines for the continent as a whole. Methods Extensive review of the literature. Results and conclusions In order to minimise bleeding complications during regional anaesthetic techniques, care should be taken to avoid traumatic puncture. If a bloody tap occurs when intraoperative anticoagulation is planned, postponing surgery should be considered. Alternatively, catheters can be placed the night before surgery. Regional anaesthesia in patients receiving full anticoagulation treatment continues to be contraindicated. Catheter manipulation and removal carry similar risks to insertion and the same criteria should apply. Appropriate neurological monitoring is essential during the postoperative recovery period and following catheter removal. The final decision to perform regional anaesthesia in patients receiving drugs that affect haemostasis has to be taken after careful assessment of individual risks and benefits.

Percutaneous Fetoscopic Patch Coverage of Spina Bifida Aperta in the Human – Early Clinical Experience and Potential

Objective: The current operative approach for fetal repair of spina bifida aperta requires maternal laparotomy and hysterotomy. Following technical feasibility studies in sheep, we performed percutaneous fetoscopic patch coverage of this lesion in 3 human fetuses between 23 + 4 and 25 + 3 weeks of gestation. Methods and Results: Whereas the patch detached in the first case 3 weeks after the procedure, it covered the exposed neural tissue in the 2 other fetuses beyond their delivery. Two of the three children survived, but 1 unexpectedly died from a ventilation problem in its 3rd week of life. In 1 of the 2 survivors, ventriculoperitoneal shunt insertion was delayed. Conclusions: Percutaneous fetoscopic patch coverage of spina bifida aperta is feasible in human fetuses and offers a substantial reduction of maternal trauma compared to open fetal repair. Further clinical experience is now required before the efficacy of the new approach to protect the exposed neural tissue from mechanical and chemical damage and to improve hindbrain herniation can be evaluated.

Postoperative analgesia after knee surgery: a comparison of three different concentrations of ropivacaine for continuous femoral nerve blockade.

BACKGROUND: The most effective ropivacaine concentration for femoral infusion after total knee arthroplasty is currently ill defined. We designed the present study to compare ropivacaine in three different concentrations (0.1, 0.2, and 0.3%) to evaluate analgesic quality, when administered as a continuous infusion with frequent infusion adjustments in patients receiving a combined femoral and sciatic nerve block. Secondary aims were to evaluate side effects such as motor blockade, rehabilitation indices, and ropivacaine plasma concentrations. METHODS: One hundred twenty-two patients undergoing total knee arthroplasty under combined general and regional anesthesia received femoral infusions of ropivacaine 0.1, 0.2, or 0.3%. Infusions were started after initial loading doses of 30 mL ropivacaine 0.5% into the femoral catheter and a sciatic catheter and were targeted to dynamic pain scores of 40 mm. Pain and side effects were assessed 1 h after tracheal extubation and on the first, second, third, fourth, and fifth postoperative days. Ropivacaine plasma concentrations were measured 24, 48, and 72 h after the start and 24 h after termination of femoral infusions in patients receiving ropivacaine 0.2% or 0.3%. RESULTS: Ropivacaine 0.1% provided ineffective analgesia. Ropivacaine 0.2% and 0.3% provided equivalent analgesia. Maximum infusion rates were 15.39 and 13.77 mL/h for ropivacaine 0.2% and 0.3%, respectively. There were no significant differences in motor blockade, mobilization, or ropivacaine plasma concentrations, which remained below toxic levels throughout the study period. CONCLUSION: Ropivacaine 0.2% and 0.3% were similar in terms of analgesic quality. Initial infusion rates should be adjusted to 15 mL/h to obtain effective analgesia.

Spinal anaesthesia for obstetrics

For a long time, epidural anaesthesia has been considered the method of choice for Caesarean delivery. The increased incidence of hypotension by the rapid onset of sympathetic blockade under spinal anaesthesia has been associated with a decline in uteroplacental blood flow and significant fetal acidosis, which may compromise neonatal well-being. Nevertheless, a decrease in fetal pH has not been shown to reduce neonatal Apgar or neurobehavioural assessment scores. Maternal blood pressure can be preserved with little side effects with low doses of vasopressors. On the other hand, spinal anaesthesia conveys significant advantages over epidural anaesthesia such as the simplicity of its use and the speed of onset, which allows neuraxial anaesthesia in urgent Caesarean sections and thus reduces the necessity for general anaesthesia. The small doses of local anaesthetics required to perform spinal anaesthesia reduce the risks of systemic toxicity to zero. Spinal anaesthesia is now considered the method of choice for urgent Caesarean section. The use of intrathecal opioids has profoundly changed the quality of spinal anaesthesia, with improved analgesia, a reduction in local anaesthetic requirements and shorter duration of motor blockade. Preliminary studies indicate that spinal anaesthesia may be safely performed in patients with severe pre-eclampsia, in whom spinal anaesthesia was previously considered contraindicated.

Operative techniques and strategies for minimally invasive fetoscopic fetal cardiac interventions in sheep.

AbstractBackground: Recent efforts to develop procedures for fetoscopic fetal cardiac interventions have been prompted by the development of severe secondary damage to the fetal heart due to semilunar valvar obstructions and the poor outcome of therapy-refractory fetal arrhythmias. The purpose of our manuscript is to analyze and share our experience with the creation of an operative setup for these procedures in sheep. Methods: We studied a total of 48 fetal sheep between 81 and 106 days of gestation (term, 145 days). After entering the amniotic cavity by a percutaneous approach, we performed various fetoscopic fetal cardiac procedures. We analyzed the success of percutaneous fetal access, methods of trocar support, the incidence and management of trocar dislodgement or accidental insertion into the chorioamniotic space, problems related to amniotic insufflation and trocar placement, as well as techniques for fetal posturing and uterine closure. Results: Percutaneous fetal access was achieved in all sheep. The use of resterilizable trocars substantially decreased the costs of our procedures. Utilizing a percutaneous transuterine purse-string suture for trocar support helped to minimize the number of nonabsorbable T-fasteners remaining inside the uterus postoperatively. As complications such as trocar dislodgement, insertion of the trocar into the chorioamniotic space, and problems with intraamniotic insufflation and gas loss were mastered, conversion to an open operative approach was never required. A novel strategy that we devised for percutaneous fetal posturing permitted adequate fetal posturing with ease and minimal trauma to the fetal skin. Conclusion: As operative techniques have become more refined, the feasibility of performing fetoscopic fetal cardiac interventions in human fetuses now depends mainly on technical improvements in imaging and interventional catheters, as well as advances in pacemaker equipment.

A century of regional analgesia in obstetrics.

T he evolution of obstetric anesthesia and analgesia has closely followed anesthesia for other subspecialties. In 1847, shortly after the first public demonstration of ether anesthesia for general surgery, James Young Simpson used diethyl ether for labor analgesia (1). Other methods followed, such as repeated injections of large doses of morphine and scopolamine. This technique, called “Dämmerschlaf” or “twilight sleep,” often led to severe maternal and neonatal respiratory depression (2). During the initial enthusiasm for alleviating maternal discomfort, proponents of obstetric analgesia gave little thought to the neonatal effects of maternal drug administration. This was, in part, because successful labor and delivery were essentially defined in terms of maternal and fetal survival, rather than physiological variables of the newborn. In 1847, Walter Channing stated that placental transfer of ether was negligible, as he could not detect an odor of ether after having cut the umbilical cord (3). Although the significance of placental drug transfer was recognized in 1877 when Paul Zweifel proved the presence of chloroform in umbilical vessels of newborns, this knowledge did not alter clinical practice over the next decades. One hundred years ago, in July 1900, the obstetrician Oscar Kreis, from Switzerland was the first to recognize the advantages of regional analgesia in obstetrics, when applying spinal cocaine to ameliorate labor pain in six parturients with a fully dilated cervix (4). Although the neonatal status was not mentioned, Kreis described the parturients as remarkably alert compared with women who received other available forms of labor analgesia. Major side effects in those early cases included a high incidence of postdural puncture headaches (PDPH) and vomiting, which occurred in half of the patients. In 1902, Hopkins subsequently performed the first cesarean delivery under spinal anesthesia in the United States. As early as 1923, the first reports on combined spinal-epidural anesthetics (CSE) in surgical patients appeared, initially as a combined single-shot technique (5). The basis of regional blocks for labor analgesia was founded on neuroanatomical principles, when Cleland (6) described the sensory innervation of the uterus in 1933. The following frequent use of spinal anesthesia by inexperienced personnel and the perception that monitoring was not necessary led to a frequent incidence of complications and brought discredit to the technique. At the time, mortality after spinal anesthesia was 1 in 1000 in surgical patients, a rate much more frequent than those observed for either local or general anesthesia (7). Mortality rates for cesarean deliveries performed under spinal anesthesia were reported to be 1 in 139 (8). Greenhill (9), engaged in obstetric anesthesia, therefore concluded that spinal anesthesia was the most dangerous of all forms of anesthesia for pregnant women. He repeatedly discouraged its use in obstetrics. The negative experiences with regional anesthesia resulted in an abandonment of pain relief in obstetrics until the 1950s, a period often described as the “dark ages of obstetric anesthesia” (1). It was during this time that “natural childbirth” and “psychoprophylaxis” were widely advocated to avoid serious anesthesia-related side effects (10). Major improvements in maternal safety were made between 1940 and 1950, when 24-hour obstetric anesthesia services were established throughout the United States. The first experiences with caudal anesthesia in obstetrics suggested that this technique might enhance safety for the parturient and the fetus, and it provided good labor pain relief (11). Parturients were more willing to accept caudal anesthesia than subarachnoid injections, as the high risk of PDPH was publicly known. In the following years, lumbar epidural analgesia gained more popularity because the success rate was more frequent, local anesthetic requirements were reduced, the onset of analgesia was faster, and the catheter was positioned in a place considered less prone for infection (12). Although the first cases of continuous lumbar epidural anesthesia were Accepted for publication June 13, 2000. Address correspondence and reprint requests to H. Van Aken, MD, PhD, FRCA, FANZCA, Klinik und Poliklinik für Anästhesiologie und operative Intensivmedizin, Westfälische Wilhelms-Universität, AlbertSchweitzer-Str. 33, D-48149 Münster, Germany. Address e-mail to hva@anit.uni-muenster.de.

A multicentre trial comparing different concentrations of ropivacaine plus sufentanil with bupivacaine plus sufentanil for patient-controlled epidural analgesia in labour

Background and objective: To determine the optimal concentration of ropivacaine for bolus-only patient-controlled epidural labour analgesia, three different doses of ropivacaine were evaluated in comparison with bupivacaine in a double-blinded multicentre study. Methods: Four hundred-and-fifty labouring parturients at term in three different academic institutions were randomized to four groups receiving bupivacaine 0.125% with sufentanil 0.75 μg mL−1, ropivacaine 0.125% or 0.175% with sufentanil 0.75 μg mL−1, or ropivacaine 0.2%. After an initial bolus of 10 mL of the study solution, and once visual analogue scores (VAS) were below 30 mm, patient-controlled epidural analgesia was initiated with a bolus of 4 mL, a lockout interval of 15 min and without a background infusion. Variables studied were the quality of analgesia, incidence of side-effects, the degree of motor blockade, and the mode of delivery. Results: Bupivacaine 0.125% and ropivacaine 0.125% with sufentanil proved equally effective in providing labour analgesia without a difference in local anaesthetic consumption (48.6 ± 23 mg bupivacaine vs. 52.1 ± 38 mg ropivacaine), motor blockade or mode of delivery. Ropivacaine 0.175% plus sufentanil enhanced the quality of analgesia of the initial loading dose, whereas ropivacaine 0.2% without sufentanil increased the consumption of local anaesthetics (80.2 ± 34 mg; P < 0.05) and the degree of motor blockade. Conclusion: Despite recent studies indicating that bupivacaine and ropivacaine may not be equipotent, both local anaesthetics provided equi-effective analgesia at equal doses without a difference in side-effects.

Fetal Plasma Concentrations after Intraamniotic Sufentanil in Chronically Instrumented Pregnant Sheep

Background Rapid progress is being made in fetal surgery. Because the fetus is capable of pain perception after the 26th week of gestation, adequate postoperative fetal pain management is essential. The preferred approach would provide fetal analgesia without affecting the mother. Intraamniotically administered sufentanil may be an interesting option if it achieves therapeutic plasma concentrations (PCs) in the fetus but not the mother. Methods After approval of the study, 25 or 50 &mgr;g sufentanil was administered intraamniotically in 10 chronically instrumented pregnant ewes. Maternal and fetal vital signs, arterial blood gases, and uterine blood flow were recorded over 120 min. Sufentanil PCs were determined before and 1, 3, 5, 10, 15, 30, 45, 60, 90, and 120 min after injection. Statistical analysis was performed using one- or two-way analysis of variance followed by Dunnett or Tukey test, as appropriate (P < 0.05; data presented as median [95% confidence interval]). Results After 25 &mgr;g sufentanil, fetal PC stabilized at 134 ± 89 pg/ml (after 10 min), and maternal PCs stabilized at 44 ± 11 pg/ml (after 15 min). After 50 &mgr;g sufentanil, fetal PCs stabilized at 134 ± 35 pg/ml (after 15 min), and maternal PCs reached 80 ± 25 pg/ml (at 30 min). Injection of 25 &mgr;g sufentanil intraamniotically did not affect maternal or fetal hemodynamics, uterine blood flow, or arterial blood gases. Fetal heart rate increased after administration of 50 &mgr;g sufentanil (maximum change at 10 min: +16 ± 12%). Conclusion The sheep fetus absorbs sufentanil after intraamniotic instillation. Significantly greater PCs were obtained in the fetal lamb as compared with the ewe. This suggests that investigation of intraamniotic opioids for fetal analgesia might be worthwhile.

Efficacy of intravenous paracetamol compared to dipyrone and parecoxib for postoperative pain management after minor-to-intermediate surgery: a randomised, double-blind trial.

Background and objective Paracetamol has a well established pharmacological profile, but its postoperative efficacy is in question. This double-blind, placebo-controlled study was designed to compare the efficacy of intravenous paracetamol with other intravenous non-opioids as part of a multimodal concept for perioperative pain therapy. Methods Patients undergoing minor-to-intermediate surgery under general anaesthesia were randomly assigned to receive infusions of paracetamol (1 g every 6 h), dipyrone (1 g every 6 h), parecoxib (40 mg every 12 h) separated by infusions of physiological saline 0.9%, or placebo (0.9% saline every 6 h), respectively, for at least 48 h as part of a multimodal pain concept. Patient-controlled piritramide was administered as rescue medication. Dependent variables were recorded 1, 6, 18, 30 and 42 h after extubation and 1 week after surgery. Surgical and associated pain was scored as the primary outcome on a visual analogue scale. Additionally, time to first dose and total piritramide dosage, satisfaction, respiratory depression, nausea, vomiting, sedation, itching and sweating were recorded. Results A total of 196 patients were recruited. The efficacy of paracetamol was similar to that of the other non-opioid analgesics. Surgical pain was reduced with all non-opioids compared to placebo; there was no effect on associated pain. Piritramide dosage and incidence of side effects were not reduced. Conclusion Intravenous paracetamol has equivalent efficacy to non-opioids dipyrone and parecoxib that improves postoperative pain therapy when used as part of a multimodal concept after minor-to-intermediate surgery.

Fetoscopic Transesophageal Electrocardiography and Stimulation in Fetal Sheep A Minimally Invasive Approach Aimed at Diagnosis and Termination of Therapy-Refractory Supraventricular Tachycardias in Human Fetuses

BACKGROUND Therapy-refractory supraventricular tachycardia commonly results in hydrops and death in human fetuses. The purpose of this study in fetal sheep was to assess the feasibility of a minimally invasive fetoscopic approach for fetal transesophageal electrocardiography and stimulation aimed at diagnosis and termination of these tachycardias. METHODS AND RESULTS We studied a total of 10 fetal sheep (87 to 103 days of gestation; term=145 days). We entered the amniotic cavity using a percutaneous fetoscopic approach and placed various electrophysiology catheters into the fetal esophagus. We recorded the number of animals in which fetoscopic transesophageal electrocardiography and stimulation were successful and assessed pacing success and thresholds for different catheters. In addition, we monitored for potential adverse effects from stimulation and for other complications of the operation. Recording of transesophageal electrocardiograms was successful in all fetal sheep. Capture during stimulation was successfully documented by additional fetal bipolar surface electrocardiograms in 7 fetuses. In fetuses in which fetal surface electrocardiograms were not recorded, pacing stimulus artifacts interfered with documentation of capture. Although stimulation thresholds were high, the maternal rhythm was not affected by fetal stimulation. CONCLUSIONS Fetoscopic fetal transesophageal electrocardiography and stimulation are feasible in fetal sheep. This minimally invasive approach might have the potential to improve diagnosis and management of therapy-refractory supraventricular tachycardias in human fetuses.