Pilot study of neuraxial imaging by ultrasound in infants and children

BACKGROUND: Ultrasonography is becoming an important adjunct in regional anesthesia. Epidural anesthesia may pose significant challenges in infants and children because of difficulties in identifying the epidural space. In addition, epidural catheters are sometimes difficult to advance. The present study was performed to evaluate an optimal ultrasound technique for direct visualization of neuraxial structures in children. METHODS: A total of 32 infants and children scheduled for minor surgery were prospectively included in a high-resolution ultrasound study. Scans were performed using either a sector or linear probe and views from a longitudinal paramedian, median and transversal angle at lumbar and thoracic levels of the spinal cord were analyzed. RESULTS: In all children investigated, the linear probe generated better images than the sector probe. Of the various scanning perspectives, the paramedian longitudinal approach offered the best views at both cord levels. Broken down by age groups, the best visibility was clearly obtained in neonates up to 3 months of age (P < 0.0001 Vs all other age groups). In older children, the quality of ultrasound decreased in an age-dependent manner. CONCLUSIONS: Paramedian longitudinal scans with linear probes are the most favorable method of imaging neuraxial anatomy at lumbar and thoracic cord levels in infants and children, with the best results in neonates up to 3 months of age. Based on these results, and using real time imaging, a practical technique for ultrasound-guided epidural anesthesia for neonates and infants at lumbar and thoracic levels of the spinal cord is planned.     

Epidural catheter placement in children: comparing a novel approach using ultrasound guidance and a standard loss-of-resistance technique

Background. We report a prospective, randomized study to evaluateultrasound guidance for epidural catheter placement in children0–6 yr of age. Methods. Epidural catheters were placed at lumbar or thoraciccord levels in 64 children undergoing major surgery, using eitherultrasonography or loss-of-resistance (LOR) for guidance. Usinga 5–10 MHz linear ultrasound probe, the neuraxial structureswere identified, the skin-epidural depth and epidural spacewas measured, the advancing epidural catheter visualized, andthe spread of local anaesthetic verifying catheter positionwas confirmed. Epidural placement procedures were analysed forbone contacts and speed of execution. Children under 6 monthswere analysed separately. Results. Epidural placement involved bone contacts in 17% ofchildren in the ultrasound group and 71% of children in theLOR group (P<0.0001). Epidurals were executed more swiftlyin the ultrasound group [162 (75) s vs 234 (138) s; P<0.01].Children under 6 months revealed a 0.9 correlation between skin-epiduraldepth and body weight. Conclusions. Ultrasonography is a useful aid to verify epiduralplacement of local anaesthetic agents and epidural cathetersin children. Advantages include a reduction in bone contacts,faster epidural placement, direct visualization of neuraxialstructures and the spread of local anaesthetic inside the epiduralspace. Ultrasound guidance requires additional training andgood manual skills, and should only be used once experiencein ultrasound-guided techniques of regional anaesthesia hasbeen acquired.     

Detection of epidural catheters with ultrasound in children

BACKGROUND: The aim of this study was to assess whether a noninvasive imaging technique such as ultrasound could visualize an epidural catheter in the epidural space in children. METHODS: Following local ethics committee approval and informed parental consent a pilot study of 12 cases was performed. Children undergoing major surgery requiring epidural analgesia were recruited. All catheters were introduced via the lumbar region. All children were scanned within 24 h of epidural insertion by consultant paediatric radiologists. If the catheter was identified in the epidural space then an attempt was made to visualize the entire length of the catheter. RESULTS: The epidural catheter was detected in nine of 12 patients. All of these were less than 6 months old. The entire length of the catheter was visualized in five of the nine patients. It was possible to estimate the most cephalad level of the catheter in seven of the nine patients. This was in the thoracic region in all cases and an appropriate level for the intended surgical procedure. It was not possible to precisely identify the tip of the catheter as a distinct entity using ultrasound. CONCLUSION: This study shows that it is possible to visualize an epidural catheter in the epidural space in children under 6 months of age using ultrasound.     

Neuraxial labor analgesia failure rates in women with a body mass index ≥50 kg/m2: a single-center retrospective study

BackgroundThe failure rate of neuraxial labor analgesia has not been investigated in super-obese women (body mass index ≥50 kg/m²).MethodsWe performed a retrospective study of neuraxial labor analgesia in super-obese women (January 2012 to August 2019). The primary outcome was the failure rate of the first neuraxial catheter. Secondary outcomes were failure rates by neuraxial technique, at cesarean delivery, and rate of catheter replacement.ResultsNeuraxial labor analgesia was used by 233 super-obese women: 153 epidural catheters placed using a combined spinal-epidural (CSE) or dural puncture epidural techniques with visualization of cerebrospinal fluid; 63 placed without dural puncture (including procedures without attempted dural puncture or attempted CSE or dural puncture epidural); and 17 intrathecal catheters (seven intentional). Thirty-two of 233 neuraxial catheters failed (13.7%, 95% Confidence Interval [CI] 9.9 to 18.7%). Epidural catheters placed using CSE or dural puncture epidural had a lower failure rate than those placed without dural puncture (9.2%, 95% CI 5.5% to 14.7%) vs 28.6% (95% CI 18.9% to 40.7%; P<0.001). Catheter migration was documented for 29.4% (95% CI 16.8 to 46.2%) of catheters that failed.ConclusionsEpidural catheters placed using CSE or dural puncture epidural techniques were more reliable than those placed without dural puncture in super-obese parturients. It is unclear whether the result was driven by grouping procedures without attempted dural puncture with those in which dural puncture was attempted but cerebrospinal fluid was not obtained. Catheter migration was a major source of failure.     

Is skin disinfection with 10% povidone iodine sufficient to prevent epidural needle and catheter contamination?

BACKGROUND AND OBJECTIVES: Epidural space infection is a potential complication of epidural catheter placement. In this study, we investigated the incidence of epidural needle and catheter contamination after skin surface disinfection with 10% povidone-iodine (PI). METHODS: Sixty seven patients having surgery under epidural anesthesia were enrolled in this prospective study. After preparation with 10% PI, skin swab cultures were taken from the site of catheter insertion. Epidural needles were cultured immediately after epidural catheters were placed. Catheters were removed at 48 hours and 2 to 3 cm of the distal tips were cultured as well. RESULTS: Fifty-six skin swabs, 52 epidural needles, and 48 catheters were cultured. Although only 3.5% (2) colonization was observed on skin surface cultures, 34.6% (18) of the epidural needles and 45.8% (22) of the catheters were colonized. No systemic or local infection was observed. CONCLUSIONS: Our results suggest that despite skin surface disinfection with PI, there is still significant risk for contamination of needles and catheters during epidural catheterization.     

Spread of local anaesthetic solution in epidural space visualisation with ultrasound in single shot caudals

Background: Ultrasonography is becoming an important adjunct in paediatric neuraxial blockade. Ultrasound guidance helps in visualisation of relevant neuraxial structures, predicting depth of epidural space from skin, reduction in bony contact and faster epidural placement. The visibility of neuraxial structures declines in patients as age increases. To date, there are no studies looking at the extent of spread of local anaesthetic solution in the epidural space and its correlation to the volume used, under ultrasound guidance. We report the results of our audit on spread of local anaesthetic solution in the epidural space in single shot caudal blocks. This abstract is based on the first 17 patients, the presentation will be based on all 50 patients. Methods: This audit was approved by the local audit committee. We aimed to follow the extent of the spread of local anaesthetic within the epidural space with real time ultrasonography. Patients were selected when the planned anaesthetic included a single shot caudal block. The anaesthetists performing the anaesthetic and the caudal block consented to our ultrasound visualisation. All patients were below 5 years of age. No attempt was made to standardise the technique, the dose, or the speed of injection. After the placement of the caudal cannula by the primary anaesthetist involved in patient care, a separate anaesthetist, experienced in using ultrasound, visualised the neuraxial structures and subsequent spread of the local anaesthetic solution with real time ultrasound. The spread was followed during the injection and for 10 s after the completion of the injection. A 5 cm 7.5–12 MHz linear array was used longitudinally with either midline or paramedian approach. Results: We are reporting the preliminary results from 17 patients. Patients were aged between 1 day and 1 year 10 months. They weighed between 3.3 kg and 14.6 kg. Either 22 gauge Jelco or Abbocath were used to perform the procedure; 0.25% or 0.20% L‐bupivacaine was used on all occasions. The volume administered per kg ranged between 0.33 and 1.27 ml. The visibility of neuraxial structures was good on all occasions. On calculating the Spearmans correlation coefficient, the extent of spread of local anaesthetic in the epidural space was positively correlated with the volume used by a correlation coefficient of 0.64, with a P value of 0.008. The postoperative pain score in recovery was 0 in 16 out of the 17 cases. The one failure occurred when the observed spread would not have been expected to provide analgesia for the performed operation. Conclusions: Among children below 5 years of age, there seems to be a positive correlation between the volume of local anaesthetic injected into the epidural space and the extent of its spread. This needs to be further investigated by a prospective randomised control trial. The utility of real time ultrasound to allow a reliable achievement of a desired level of sensory block, should be investigated i.e, whether the volume used in achieving a desired level of local anaesthetic spread, as guided by ultrasound, provides superior analgesia and fewer adverse effects compared with the volume calculated using the Armitage regimen. References 1 Rapp HJ, Folger A, Grau T. Ultrasound guided epidural catheter insertion in children. Anesth Analg 2005; 101 : 333–339. 2 Willschke H, Marhofer P, Bosenberg A, et al. Epidural catheter placement in children: comparing a novel approach using ultrasound guidance and a standard loss of resistance technique. Br J Anaesth 2006; 97 : 200–207. 3 Marhofer P, Bosenberg A, Sitzwohl C et al. Pilot study of neuraxial imaging by ultrasound in infants and children. Pediatr Anesth 2005; 15 : 671–676.     

Incidence and characteristics of failures in obstetric neuraxial analgesia and anesthesia: a retrospective analysis of 19,259 deliveries

A retrospective analysis was performed on 19,259 deliveries that occurred in our institution from January 2000 to December 2002. Anesthesia records and quality assurance data sheets were reviewed for the characteristics and failure rates of neuraxial blocks performed for labor analgesia and anesthesia. The neuraxial labor analgesia rate was 75% and the overall failure rate was 12%. After adequate analgesia from initial placement, 6.8% of patients had subsequent inadequate analgesia during labor that required epidural catheter replacement. Ultimately 98.8% of all patients received adequate analgesia even though 1.5% of patients had multiple replacements. Six percent of epidural catheters had initial intravenous placement but 46% were made functional by simple manipulations without higher subsequent failure. Unintended dural puncture occurred in 1.2% of labor neuraxial analgesia. The incidences of overall failure, intravenous epidural catheter, wet tap, inadequate epidural analgesia and catheter replacement were lower in patients receiving combined spinal-epidural versus epidural analgesia. For cesarean section, 7.1% of pre-existing labor epidural catheters failed and 4.3% of patients required conversion to general anesthesia. Spinal anesthesia for cesarean section had a lower failure rate of 2.7%, with 1.2% of the patients requiring general anesthesia. The overall use of general anesthesia decreased from 8% to 4.3% over the three-year period. Furthermore, regional anesthesia was used in 93.5% of cesarean deliveries with no anesthetic-related mortalities. Future investigations should identify acceptable international standards, risk factors associated with failure and methods to reduce failure before cesarean section.     

Does epinephrine improve the diagnostic accuracy of aspiration during labor epidural analgesia?

Aspiration reliably detects almost all IV multiorifice epidural catheters. Although a supplemental epinephrine 15-microg test dose may detect the rare IV catheter that does not yield blood on aspiration, false-positive epinephrine responses may cause some women to unnecessarily undergo repeat epidural catheter insertion. We evaluated 532 consecutive eligible patients requesting neuraxial labor analgesia. Patients were excluded if they had a contraindication to epinephrine or if they received intrathecal sufentanil/bupivacaine. Multiorifice catheters were inserted 4-6 cm into the epidural space as part of an epidural (n = 305) or combined spinal-epidural (n = 270) technique. We used aspiration, a lidocaine/epinephrine test dose, and bolus injection or infusion of dilute bupivacaine/sufentanil solutions to systematically determine IV, intrathecal, or epidural catheter location. Aspiration alone detected 47 of 48 intravascular catheters. There were 10 positive epinephrine responses: 2 were true positives, 7 were falsely positive (subsequent local anesthetic injection/infusion produced bilateral sensory change and analgesia), and 1 catheter was removed without further testing. Aspiration detected almost all intravascular catheters. Although the epinephrine test dose did detect one catheter that proved to be in a blood vessel, 87.5% of positive responses occurred in women without intravascular catheters. IMPLICATIONS: Epidural catheters may enter a blood vessel. Many clinicians use epinephrine to detect these catheters. Because aspiration alone detects almost all IV multiorifice catheters in laboring women, a subsequent epinephrine test dose may be unnecessary.     

A comparison of 7 types of epidural catheters

The stiffness on bending of 7 types of epidural catheters was measured with the help of a cantilever beam. 1415 patients scheduled for lithotripsy, requiring epidural anesthesia, were selected and randomly assigned to receive one of the catheters. The patients were divided into 2 groups according to the resistance to insertion. The incidence of intravenous insertion, subarachnoid location and paresthesia during catheter insertion were assessed. The position of epidural catheters was studied radiographically in 1276 of 1415 patients. There were no significant difference among 7 types of epidural catheters as far as the incidence of intravenous insertion, subarachnoid insertion or straight lying of catheter in epidural space were concerned. When the catheter was hard or pushed against the resistance to insertion, the incidence of paresthesia increased. When the catheter was hard and pushed against the resistance to insertion, transforaminal escape increased. A soft catheter should be chosen to minimize the incidence of paresthesia or transforaminal escape.     

Malposition of epidural catheter: an 8-year retrospective analysis on an incident reporting system at an urban university hospital

Epidural anesthesia is widely used in patients who undergo thoracic, abdominal or lower extremity surgeries and generally considered useful for perioperative analgesic management. Epidural catheterization is often associated with some complications including misplacement of the catheter. Epidural catheters are known to be misplaced or migrate into subarachnoidal space, subdural space, vessels and thoracic cavities ; however, frequency, predominant sites of misplacement, and the timing of detection are not fully understood regarding the misplacement of the catheters. In this retrospective study, our incident reporting system dealt with a period of 8 years (from 1999 to 2007) at our university hospital. Out of 8 patients who had misplacement of the catheter, 6 patients were male and 2 patients were female. Epidural catheters were misplaced to subarachnoid space in 6 cases and thoracic cavity in 2 cases. The misplacement of the catheters was found before the induction of general anesthesia in 2 patients, after induction of general anesthesia in 1 patient, during surgical procedure in 3 patients, and postoperatively in 2 patients. Since misplacement of epidural catheters can occur at any moment during perioperative period, continuous monitoring and observation of patients seem to be very important to prevent and minimize the adverse events related to the misplacement of epidural catheters.     

Administration of local anesthetic through the epidural needle before catheter insertion improves the quality of anesthesia and reduces catheter-related complications

Epidural catheter placement offers flexibility in block management. However, during epidural catheter insertion, complications such as paresthesia and venous and subarachnoid cannulation may occur, and suboptimal catheter placement can affect the quality of anesthesia. We performed this prospective, randomized, double-blind study to assess the effect of a single-injection dose of local anesthetic (20 mL of 2% lidocaine) through the epidural needle as a priming solution into the epidural space before catheter insertion. We randomized 240 patients into 2 equal groups and measured the quality of anesthesia and the incidence of complications. In the needle group (n = 100), catheters were inserted after injection of a full dose of local anesthetic through the needle. In the catheter group (n = 98), the catheters were inserted immediately after identification of the epidural space. Local anesthetic was then injected via the catheter. We noted the occurrence of paresthesia, inability to advance the catheter, or IV or subarachnoid catheter placement. Sensory and motor block were assessed 20 min after the injection of local anesthetic. Surgery was initiated when adequate sensory loss was confirmed. In the catheter group, the incidence of paresthesia during catheter placement was 31.6% compared with 11% in the needle group (P = 0.00038). IV catheterization occurred in 8.2% versus 2% of patients in the catheter and needle groups, respectively (P = 0.048). More patients in the needle group had excellent surgical conditions than the catheter group (89.6% versus 72.9; P < 0.003). We conclude that giving a single-injection dose via the epidural needle before catheter placement improves the quality of epidural anesthesia and reduces catheter-related complications.     

Ultrasound-guided epidural block

Epidural block is performed with surface landmark guidance and loss of resistance technique. Ultrasound visualization of the spinal column and surrounding structures gives additional anatomical information, which could make the block easier and safer. Previous studies revealed that there is strong correlation between the depth of the epidural space measured using ultrasound and the depth of the needle inserted. In order to obtain an image of the spinal canal, the ultrasound probe is positioned at the interspace of spinous processes in transverse and longitudinal planes. The dura mater is identified as an echogenic structure inside the spinal canal. Prepuncture ultrasound examination offers useful information for epidural block such as puncture point and depth as well as angle to the epidural space.     

Neuraxial hematoma after combined regional anesthesia: conservative resolution

Epidural hematoma is a rare but serious neurological complication of neuraxial anesthesia. We report the case of a woman in whom this complication presented after knee replacement surgery under combined neuraxial anesthesia. No adverse events occurred during surgery. In the early postoperative period thromboembolic prophylaxis and continuous perfusion of ropivacaine were started through the epidural catheter. Lumbar pain along with sensorimotor alterations in the lower limbs developed on the first day after surgery. Epidural hematoma was suspected and the perfusion of local anesthetic was suspended. A computed tomography scan confirmed the presence of a hematoma with poorly defined margins. The patient was transferred to another hospital for dorsolumbar magnetic resonance, which revealed an extensive hematoma. Surgery was ruled out in favor of conservative treatment. Neurological symptoms resolved slowly over the following days and the patient was discharged partially recovered 51 days after surgery and recovery was complete within 6 postoperative months. We discuss the prevalence, etiology, and treatment of neuraxial hematoma related to local or regional anesthesia.     

Clinical signs of infection during continuous postoperative epidural analgesia in children: the value of catheter tip culture

BACKGROUND: Infection arising from the use of epidural catheters for postoperative analgesia is a major source of anxiety. METHODS: The routine culture of epidural catheter tips were studied in 100 consecutive children aged 1 day to 15 years. Epidural catheters were inserted aseptically in accordance with an agreed protocol. The catheter site was inspected regularly and the tip sent for microbiological culture following removal. RESULTS: Local signs of inflammation at the epidural site were seen in 16% of children, and bacteria were isolated from catheter tip culture in 32%. Positive catheter tip culture was found in 43% of children with local signs of inflammation and of the remaining children with no local signs, organisms were isolated from the catheter tip in 30%. Culture of skin swabs and catheter tips in two patients with purulent discharge at the epidural site yielded the same organism. No correlation between the number of attempts at catheter insertion and either local signs of inflammation or positive catheter tip cultures were found. CONCLUSIONS: Minor local signs of inflammation and infection are common in pediatric patients during continuous epidural infusion. Epidural catheter tips are also frequently culture positive in patients with and without local signs and who may not go on to develop further signs or symptoms of infection. Routine culture of catheter tips is unnecessary as it is not a good predictor of epidural space infection.     

Neuraxial blockade using image intensifier in patients after spinal instrumentation

There is scant information in the literature regarding central neuraxial blockade in patients with previous back surgery or severe kyphoscoliosis. This report describes a 58-year-old female and an 84-year-old female with spinal instrumentation who presented for orthopedic surgery under neuraxial blockade. In both cases, multiple attempts of needle insertion using standard technique were unsuccessful, whereas spinal combined with epidural anesthesia was performed successfully using image intensifier. The anatomical considerations and difficulties in achieving reliable neuraxial blockade after spinal instrumentation are reviewed. Neuraxial blockade using image intensifier may provide less technical difficulty and a more reliable result in such patients.     

Anesthesia and lumbar epidural anesthesia in an infant with third-degree burns

Epidural route is widely used in adults for injection of drugs, but it is not so often used in pediatric patients. We present the case of a 8 month old burned infant who received anesthesia and analgesia through a lumbar epidural catheter. The insertion of epidural catheter is described. Two surgical procedures were performed under epidural anesthesia with 0.5% bupivacaine an epinephrine 1:200.000 (2.5 mg/kg). 16 hours of postoperative analgesia was obtained with epidural morphine (0.05 mg/kg). No side effects were seen. We analyze the uses of epidural anesthesia in pediatric patients, the catheter care in the burned child, the hemodynamic changes observed during anesthesia and the results of peridural morphine.     

The risk of vertebral canal complications in 2837 cardiac surgery patients with thoracic epidurals

BACKGROUND: Recent communications in the medical press have suggested that the rate of vertebral canal complications following epidural catheter placement is increasing in frequency, in particular the incidence of epidural abscess (Hearn M. Epidural abscess complicating insertion of epidural catheters. Br J Anaesth 2003; 90 (5): 706-7; Govasi C, Bland D, Poddar R, Horst C. Epidural abscess complicating insertion of epidural catheters. Br J Anaesth 2004; 92 (2): 294-5). We wished to investigate this in our population of cardiac surgical patients. METHODS: We performed a retrospective review of the data from all patients who had undergone coronary artery bypass grafting or valve replacement surgery in our hospital over the past 8 years. This involved a review of computer databases, logbooks, radiology records, admission records, intensive care transfers, pain team ward round data and follow-up outpatient data referrals. RESULTS: In total, 2837 patient admissions were examined and reviewed by the authors. No episodes of vertebral canal haematoma or abscess were observed. CONCLUSIONS: Retrospective analysis of our working practice indicates that thoracic epidural anaesthesia and analgesia are safe in patients receiving cardiac surgery. We found no epidural haematoma or abscess in 2837 patients.     

Effects of epidural anesthesia on sympathetic nerve discharge to the skin

Direct intraneural recordings of skin sympathetic activity (SSA) were performed to determine the magnitude of blockade of sympathetic fibers to the lower extremities during epidural anesthesia. Lumbar epidural catheters were inserted in nine volunteers. Multiunit postganglionic sympathetic activity was recorded in a skin fascicle of the peroneal nerve before and after injection of 4 ml of mepivacaine 2% epidurally, followed by an additional 12-16 ml after 5 min. Arousal stimuli such as sudden loud noises and noxious electrical skin stimulation were used to elicit transient sympathetic activation. Epidural anesthesia with upper level of sensory blockade at T4-T8 (n = 7) completely blocked spontaneous SSA and no detectable skin sympathetic activity could be provoked by arousal stimuli later than 14 min after the test dose. Sympathetic blockade was accompanied by marked increases in foot skin blood flow and loss of skin resistance responses to arousal. Epidural anesthesia with sensory blockade up to T10-11 (n = 2) only produced a partial sympathetic blockade. The result shows that epidural anesthesia with sensory blockade at T8 or above is equally as effective as injections of local anesthetics directly at postganglionic nerve fibers or ganglionic blockade in producing a complete sympathetic blockade of intraneurally recorded SSA. This neural blockade was paralleled by skin vasodilatation and a loss of sudomotor responses in the foot.     

Practice advisory on the prevention and management of complications of pediatric regional anesthesia

Study objectivesTo develop evidence-based recommendations for prevention and management of infections, bleeding, and local anesthetic toxicity in children undergoing regional anesthesia.DesignA joint committee of the European Society of Regional Anesthesia and Pain Therapy (ESRA) and the American Society of Regional Anesthesia and Pain Medicine (ASRA) studied electronic literature databases of pediatric regional anesthesia to construct evidence-based recommendations.Main resultsFor epidural anesthesia lumbar or thoracic placement is preferred. Skin preparation prior to block placement with chlorhexidine is preferred to povidone iodine. A tunneled catheter technique is suggested when using the caudal route or if the epidural catheter placement is kept in situ for more than 3 days. Inspection of the epidural catheter insertion site should be performed at least once a day as part of the postoperative management. When medical and physical examination is normal, coagulation tests are usually unnecessary but if coagulation tests are abnormal, neuraxial and deep peripheral nerve blocks are contraindicated. For patients receiving Low Molecular Weight Heparin thromboprophylaxis, a safety interval of two half-lives plus the time required for heparin to reach maximal levels is considered an adequate compromise between bleeding risk and thrombosis risk when removing epidural catheters. Ultrasound-guided peripheral nerve blocks reduce the risk of vascular puncture and thus the risk of local anesthetic toxicity is reduced.ConclusionsIn children undergoing regional anesthesia the incidence of infection, hematoma, and local anesthetic toxicity is low. The ASRA/ESRA joint committee proposes a practice advisory to prevent and treat these complications.