Renate Conradi

Efficacy of ultrasound imaging in obstetric epidural anesthesia

STUDY OBJECTIVE To assess the clinical use of ultrasonographic localization of the epidural space, and to evaluate the clinical efficacy of ultrasound diagnostics in obstetric anesthesia. DESIGN Randomized prospective study. SETTING University Clinic of Obstetrics and Gynecology. PATIENTS 300 parturients, 85 of whom had conventional delivery and 65 who underwent cesarean section. INTERVENTIONS Patients underwent ultrasonography for the identification of the intervertebral structures. Puncture depth and angle were measured to improve the placement of the Tuohy needle. MEASUREMENTS In the ultrasound group, additional puncture data, optimized puncture point, expected puncture depth, and angle were used to optimize the puncture technique. To control for side effects, we compiled data on the number of puncture attempts and the number of necessary puncture levels, visual analog scale (VAS) scores, the rate of side effects, and the patient acceptance of the technique. MAIN RESULTS The two groups were similar regarding demographic data. Using ultrasound for structure detection, the rate of puncture attempts were significantly (p < 0.013) reduced from 2.18 +/- 1.07 to 1.35 +/- 0.61. The mean rate of necessary puncture levels was 1.30 +/- 0.55 and with ultrasound detection 1.136 +/- 0.36 (p < 0.029). Complete analgesia was achieved in 147 patients with ultrasound detection versus 138 patients in the Control group (p < 0,03). The maximum VAS pain score in the control group was 1.3 +/- 2.1 versus 0.8 +/- 1.5 in the Ultrasound group (p < 0.006). The rate of side effects were reduced significantly: 99 patients in the Control group had no side effects compared with 120 patients from the Ultrasound group who were free of side effects. Patient acceptance of the technique in the Ultrasound group was significantly higher than in the Control group. CONCLUSION The clinical use of ultrasound for epidural catheter placement may improve regional anesthesia. The use of ultrasound resulted in superior quality in all measured endpoints.

Ultrasound imaging improves learning curves in obstetric epidural anesthesia: a preliminary study.

PurposeEpidural anesthesia may be difficult in pregnancy. We intended to evaluate the teaching possibilities of ultrasonography as a diagnostic approach to the epidural region.MethodsTwo groups of residents performed their first 60 obstetric epidurals under supervision. One proceeded in the conventional way using the loss of resistance technique (control group = CG). The other group proceeded in the same way but was supported by prepuncture ultrasound imaging, giving them information about the optimal puncture point, depth and angle (ultrasound group = UG). Success was defined as adequate epidural anesthesia requiring a maximum of three attempts, reaching a visual analogue scale score of less than I, while neither changing the anesthesia technique, nor starting at another vertebral level. In addition, intervention by the supervisor was defined as failure.ResultsIn the CG we observed asuccess rate of 60% ± 16% after the first ten attempts followed by a nearly continuous rise of the learning curve. Within the next 50 epidurals the rate of success increased to 84%. In the UG the rate of success started at 86% ± 15%. Wthin 50 epidural insertions it rose up to a level of 94%. The difference between the two groups remained significant (P < 0.001).ConclusionUsing ultrasound imaging for teaching epidural anesthesia in obstetrics we found a higher rate of success during the first 60 attempts compared to conventional teaching. We believe this shows the possible value of ultrasound imaging for teaching and learning obstetric regional anesthesia.RésuméObjectifL’anesthésie épidurale peut être difficile à réaliser pendant la grossesse. Nous avons voulu évaluer les possibilités d’apprentissage de l’échographie comme approche diagnostique de la région épidurale.MéthodeDeux groupes de résidents ont réalisé leurs 60 premières anesthésies épidurales sous supervision. Un premier groupe a procédé de manière traditionnelle selon la technique de perte de résistance (groupe témoin = GT). Lautre groupe a fait la même chose, mais bénéficiait de l’assistance de l’échographie qui donnait des informations sur les meilleurs site, profondeur et angle de ponction (groupe d’échographie = GE). La réussite était une anesthésie épidurale adéquate exigeant au plus trois essais, affichant un score de moins de I à l’échelle visuelle analogique et n’exigeant pas de modifier la technique anesthésique, ni de faire la ponction à un autre niveau vertébral. De plus, l’intervention d’un superviseur constituait un échec.RésultatsUn taux de un succès de 60% ± 16% a été noté dans le GT après les 10 premières tentatives suivies par une hausse presque continue de la courbe d’apprentissage. Pendant les 50 anesthésies suivantes, le taux est monté à 84 %. Dans le GE, le taux a été d’abord de 86 % ± 15 %, puis, pour les 50 anesthésies suivantes, il s’est élevé à 94 %. La différence intergroupe demeurait donc significative. (P < 0,001).ConclusionLutilisation de l’échographie dans l’enseignement de l’anesthésie épidurale obstétricale, comparée à la méthode traditionnelle d’enseignement, a montré un taux de succès plus élevé pendant les 60 premiers essais. Cette expérience démontre la valeur de l’échographie dans l’enseignement et l’apprentissage de l’anesthésie obstétricale régionale.

Ultrasound control for presumed difficult epidural puncture

Background: The efficacy of epidural anaesthesia depends on the accurate identification of the epidural space (ES). Abnormal anatomical conditions may make the procedure difficult or impossible. The aim of this study was to investigate whether pre‐puncture ultrasound examination of the spinal anatomy might be beneficial in expected cases of difficult epidural anaesthesia.

Paramedian access to the epidural space: the optimum window for ultrasound imaging

STUDY OBJECTIVE To establish a useful ultrasonic approach to the epidural space so as to optimize pre-puncture diagnostics. DESIGN Prospective study. SETTING University clinic. PATIENTS 60 participants (19 to 34 years of age), 40 healthy volunteers (20 male, 20 female) and 20 parturients. INTERVENTIONS Ultrasound scanning of the lumbar spine was performed at the L(3)-L(4) vertebral interspace. Three ultrasound planes were employed: the transverse, median, and paramedian longitudinal approaches. MEASUREMENTS We compared the width of the ultrasound-permeable area in the median and paramedian planes and assessed the visibility of the epidural space and its surrounding structures. MAIN RESULTS In the paramedian plane, the permeable window was larger (p < 0.001) than in the median approach. The visibility of the ligamentum flavum (p < 0.0001), dura mater (p < 0.0001), and cauda equina (p < 0.0001) was significantly higher. Pulsation of epidural vessels could be observed more frequently (p < 0.0001) in the paramedian plane. CONCLUSIONS The longitudinal paramedian plane provided information about the epidural space depth in excellent imaging quality. The additional information might be beneficial in epidural anesthesia and in other clinical specialties (e.g., neurosurgery, trauma care).

Ultraschall und Periduralanästhesie : Technische Möglichkeiten und Grenzen einer diagnostischen Untersuchung des Periduralraums

ZusammenfassungDie Periduralanästhesie (PDA) ist heute das wichtigste geburtshilfliche Analgesieverfahren. Sie wird durch schwangerschaftsbedingte Bindegewebsveränderungen erschwert, die u. a. einen verfrühten “loss of resistance” vortäuschen können. Diagnostische Maßnahmen vor der PDA beschränken sich derzeit auf Inspektion und Palpation. Eine Etablierung diagnostischer Hilfsmittel ist anzustreben. Vor der Anlage einer geburtshilflichen Periduralanästhesie wurde bei 100 Schwangeren prospektiv eine Ultraschalluntersuchung der lumbalen Wirbelsäule durchgeführt. Die Erkennbarkeit aller anatomischen Strukturen wurde bewertet, und die sonographisch gefundenen Entfernungen wurden mit den bei der Punktion vorgefundenen Werten verglichen. Die Korrelation zwischen vor bzw. bei der Punktion gemessenen Werten war mit r2=0,79 hoch. Zwischen Ultraschall- und Punktionswinkel ergab sich jedoch nur eine geringe Abhängigkeit (r2=0,19). Der zeitliche Abstand von Ultraschalluntersuchung und Punktion bedingt eine unvermeidbare Unschärfe: jede Abweichung zwischen Schall- und Punktionsgegebenheiten verursacht Veränderungen der Punktionstiefe. Die Patientenakzeptanz des Verfahrens war sehr gut. Die Ultraschalldiagnostik bietet eine Möglichkeit, Punktionsrichtung und Abstand des Epiduralraums zur Haut noch vor dem Punktionsversuch festzulegen. Die ultraschallgesteuerte PDA für Schwangere lässt sich problemlos in den klinischen Alltag einfügen. Ultraschall kann damit eine wichtige diagnostische Lücke in der Regionalanästhesie füllen.AbstractEpidural anaesthesia (EA) is the most important analgesia technique in obstetrics for delivery. In pregnancy, hormonal adjustments lead to an alteration of tissue consistency, which often causes an early, untimely loss of resistance. Apart from mere inspection and palpation, no useful diagnostic method prior to EA performance has been established yet. In this prospective study, we examined 100 pregnant women, who had been admitted for childbirth and were undergoing epidural block (level L3–L4) for delivery. Sonotopography of the lumbar epidural structures was performed directly before epidural puncture and childbirth. We evaluated the visibility of all anatomical structures and compared all distances measured by ultrasonography and during puncture. The correlation between distances measured by ultrasound and by puncture needle was high (r2=0.79). No obvious dependency was found between ultrasonic and puncture angle (r2=0.19). The temporal distance from ultrasonic examination and puncture causes unavoidable differences: each deviation between ultrasound and puncture conditions causes a modification of the puncture depth. The patient acceptance of the procedure was very good. Ultrasonography offers the possibility to determine site and direction of epidural puncture and distance of the epidural space to the skin even before the puncture attempt. The ultrasound controlled EA for delivery can easily be inserted into the clinical routine. Ultrasonography can fill an important diagnostic gap in regional anaesthesia.

Ultraschall und Regionalanästhesie

ZusammenfassungDie diagnostische Anwendung von Ultraschall mit der Darstellung der Punktionsebene und des Epiduralraumes hat Auswirkungen auf den Ablauf und die Qualität einer Periduralanästhesie.Die vorliegende Arbeit zeigt einen Überblick über die bisherigen Erfahrungen mit Ultraschall im Rahmen der Periduralanästhesie und gibt einen Ausblick auf die Möglichkeiten bildgebender Verfahren in der Regionalanästhesie.Die verschiedenen Arbeitsgruppen, die sich mit Ultraschall und Periduralanästhesie beschäftigen, fanden Korrelationen von 0,79–0,98 zwischen der vorhergesagten und der effektiv gemessenen Punktionstiefe; die Präzision lag zwischen 5,7 mm und 7,7 mm.Die Bestimmung des erwarteten Punktionswinkels ergab eine nur geringe Korrelation zwischen 0,07 und 0,31; die Präzision der gemessenen Werte lag zwischen 10° und 13,4°.In allen Studien konnte eine positive Beeinflussung der Periduralanästhesie durch die Anwendung von Ultraschall im Sinne einer signifikanten Erniedrigung (p<0,03) der Punktionsversuche gezeigt werden.Darüber hinaus konnte durch dieses Verfahren die Anzahl notwendiger Punktionsebenen signifikant (p<0,05) reduziert werden.Die ultraschallunterstützte Punktion ermöglicht einen idealeren Punktionsablauf und eine exaktere Applikation des Periduralkatheters.In Untersuchungen konnte eine signifikante Verbesserung der Analgesie (p<0,035) und der Patientenzufriedenheit (p<0,006) gezeigt werden.Die Metaanalyse der verschiedenen Untersuchungen zur Punktionsqualität bei ultraschallunterstützter Periduralanästhesie ergab einen deutlichen Vorteil zugunsten der Anwendung bildgebender Methoden.AbstractThe use of ultrasound as a diagnostic tool for the visualisation of the epidural space has effects on the quality and the performance of epidural anesthesia.This work presents an overview of the recent experiences with ultrasound for epidural anesthesia and on the possibilities for ultrasound imaging techniques.The results of visualisation of the epidural space and its limiting structures obtained by various working groups are presented.We review all presently available data on the prediction of the puncture depth.The various working groups found correlations between predicted and effective puncture depth between 0.79 and 0.98 and the precision of the measurement was 57–7.7 mm.Regarding the prediction of the puncture angle there was a poor correlation ranging between 0.07 and 0.31.The precision between the measured and the punctured angles was found to be 10–13.4°. In all available prospective randomised studies on the puncture effects in the lumbar epidural space, the influence of ultrasound showed a significant reduction (p<0.03) of the puncture attempts,and we found a significant (p<0.05) reduction in the number of puncture levels.The ultrasound-guided puncture allowed an ideal needle trajectory and a more precise application of the catheter. A significant improvement of analgesia quality (p<0.035) and patient satisfaction (p<0.006) could be achieved.The metaanalysis of the different studies regarding puncture quality by ultrasound-guided peridural anaesthesia showed a clear advantage for the use of imaging techniques.

The Treatment of Hypercatabolic Acute Renal Failure by Adequate Nutrition and Haemodialysis

Despite all therapeutic advances, the management of acute renal failure in surgical cases still involves many unsolved problems. In our dialysis unit, 100 surgical patients aged from 9 weeks to 82 years, had to be dialysed for established acute renal failure. Tubular necrosis developed within posttraumatic crush syndromes, haemorrhagic shock or following extensive abdominal, cardiovascular or urological surgery, in many cases complicated by septicaemia. Hypercatabolism with a daily plasma urea increment exceeding 60 mg/100 ml played a dominating role in the course of most of the severely ill patients.