Standardizing nomenclature in regional anesthesia: an ASRA-ESRA Delphi consensus study of upper and lower limb nerve blocks.

BACKGROUND: Inconsistent nomenclature and anatomical descriptions of regional anesthetic techniques hinder scientific communication and engender confusion; this in turn has implications for research, education and clinical implementation of regional anesthesia. Having produced standardized nomenclature for abdominal wall, paraspinal and chest wall regional anesthetic techniques, we aimed to similarly do so for upper and lower limb peripheral nerve blocks. METHODS: We performed a three-round Delphi international consensus study to generate standardized names and anatomical descriptions of upper and lower limb regional anesthetic techniques. A long list of names and anatomical description of blocks of upper and lower extremities was produced by the members of the steering committee. Subsequently, two rounds of anonymized voting and commenting were followed by a third virtual round table to secure consensus for items that remained outstanding after the first and second rounds. As with previous methodology, strong consensus was defined as ≥75% agreement and weak consensus as 50%-74% agreement. RESULTS: A total of 94, 91 and 65 collaborators participated in the first, second and third rounds, respectively. We achieved strong consensus for 38 names and 33 anatomical descriptions, and weak consensus for five anatomical descriptions. We agreed on a template for naming peripheral nerve blocks based on the name of the nerve and the anatomical location of the blockade and identified several areas for future research. CONCLUSIONS: We achieved consensus on nomenclature and anatomical descriptions of regional anesthetic techniques for upper and lower limb nerve blocks, and recommend using this framework in clinical and academic practice. This should improve research, teaching and learning of regional anesthesia to eventually improve patient care.

Feasibility of an ultrasound-guided approach to radiofrequency ablation of the superolateral, superomedial and inferomedial genicular nerves: a cadaveric study.

INTRODUCTION: Genicular nerve radiofrequency (RF)denervation appears to be a promising treatment for knee pain in patients with degenerative osteoarthritis of the knee, when candidates are not suitable for arthroplasty. This study aimed to assess the accuracy and reliability of ultrasound-guided placement of RF cannulas in cadavers for genicular nerve treatment, by measuringthe needle-to-nerve proximity. MATERIALS AND METHODS: Five soft-fix human cadavers were included in this study, totaling 10 knees (meanage 93.8 years). Using the ultrasound-guided technique,which we have described previously, RF cannulas were directed toward the superolateral genicular nerve(SLGN), the superomedial genicular nerve (SMGN) and the inferomedial genicular nerve (IMGN). Indocyaninegreen (ICG) dye (0.1 mL) was infiltrated. An anatomical dissection was performed and the distance from the center of the ICG mark to the genicular nerve concerned was measured. RESULTS: The mean distances from the center of the ICG mark to the SLGN, SMGN and IMGN were 2.33 mm(range 0.00-6.05 mm), 3.44 mm (range 0.00-10.59mm) and 1.32 mm (range 0.00-2.99 mm), respectively. There was no statistical difference in distances from the center of the ICG mark to the targeted nerve between the different nerves (p=0.18). CONCLUSION: The results of this study demonstrate that ultrasound-guided treatment of the genicular nerves is feasible. However, for RF ablations, there are some limitations, which mostly can be overcome by using appropriate RF ablation settings.

Fascia iliaca compartment blocks: Different techniques and review of the literature.

The fascia iliaca compartment block has been promoted as a valuable regional anesthesia and analgesia technique for lower limb surgery. Numerous studies have been performed, but the evidence on the true benefits of the fascia iliaca compartment block is still limited. Recent anatomical, radiological, and clinical research has demonstrated the limitations of the landmark infrainguinal technique. Nevertheless, this technique is still valuable in situations where ultrasound cannot be used because of lack of equipment or training. With the introduction of ultrasound, a new suprainguinal approach of the fascia iliaca has been described. Research has demonstrated that this technique leads to a more reliable block of the target nerves than the infrainguinal techniques. However, more research is needed to determine the place of this technique in clinical practice.

Supra-inguinal injection for fascia iliaca compartment block results in more consistent spread towards the lumbar plexus than an infra-inguinal injection: a volunteer study.

BACKGROUND AND OBJECTIVES: Lumbar plexus block has been used to provide postoperative analgesia after lower limb surgery. The fascia iliaca compartment block (FICB) has been proposed as an anterior approach of the lumbar plexus targeting the femoral, obturator and lateral femoral cutaneous nerve. However, both radiological and clinical evidence demonstrated that an infra-inguinal approach to the fascia iliaca compartment does not reliably block the three target nerves.We hypothesized that a supra-inguinal approach of the fascia iliaca compartment results in a more consistent block of the three target nerves than an infra-inguinal approach. METHODS: We performed a randomized controlled, double-blind trial in 10 healthy volunteers. Both an infra-inguinal FICB (I-FICB) and a supra-inguinal FICB (S-FICB) were performed on the left or the right side in each volunteer. Forty milliliters of lidocaine 0.5% was injected with each approach. Sensory and motor block and spread of local anesthetics (LA) on MRI were assessed. RESULTS: After an S-FICB, 80% of the volunteers had a complete sensory block of the medial, anterior and lateral region of the thigh, compared with 30% after an I-FICB (p=0.035). There was an insignificant effect on motor function with both approaches. After an S-FICB, in 8 out of 10 volunteers there was spread of LA in the expected anatomic location of the obturator nerve on MRI compared with 1 out of 10 volunteers after an I-FICB (p=0.0017). The cranial spread of LA after an S-FICB on MRI was higher than after an I-FICB (p=0.007), whereas there was a more caudal spread of LA on MRI after an I-FICB than after an S-FICB (p=0.005). CONCLUSIONS: An S-FICB produces a more complete sensory block of the medial, anterior and lateral region of the thigh, compared with an I-FICB. Our study demonstrates that an S-FICB with 40 mL of LA more reliably spreads LA to the anatomical location of the three target nerves of the lumbar plexus on MRI than an I-FICB. An S-FICB also leads to a more consistent spread in a cranial direction under the fascia iliaca and around the psoas muscle. CLINICAL TRIAL REGISTRATION: This work was registered with the European clinical trial registry: Identifier Eudra CT 2015-004607-24.

Gamma-hydroxybutyrate (GHB), an unusual cause of high anion gap metabolic acidosis.

The causes of high anion gap metabolic acidosis (HAGMA) are well described in the literature. However, sometimes more frequent causes of HAGMA cannot explain its occurrence.In the case of HAGMA and severe neurological depression in the absence of other causes of HAGMA, clinicians should consider an intoxication with gamma-hydroxybutyrate (GHB) as a possible cause.GHB is endogenous to the mammalian central nervous system (CNS). Synthetic GHB was initially used as an anesthetic but is now only licensed for medical use in a limited number of indications such as the treatment of narcolepsy. Because of its euphoric effects, it became popular for recreational use under the street names: Liquid Ecstasy, Georgia Home Boy, and Liquid G.We describe the clinical case of a patient who suffered from severe neurological depression and HAGMA.

A Longitudinal Supra-Inguinal Fascia Iliaca Compartment Block Reduces Morphine Consumption After Total Hip Arthroplasty.

BACKGROUND AND OBJECTIVES: The role of a fascia iliaca compartment block (FICB) for postoperative analgesia after total hip arthroplasty (THA) remains questionable. High-dose local anesthetics and a proximal injection site may be essential for successful analgesia. High-dose local anesthetics may pose a risk for local anesthetic systemic toxicity. We hypothesized that a high-dose longitudinal supra-inguinal FICB is safe and decreases postoperative morphine consumption after anterior approach THA. METHODS: We conducted a prospective, double blind, randomized controlled trial. Patients scheduled for THA were randomized to group FICB (longitudinal supra-inguinal FICB with 40-mL ropivacaine 0.5%) or group C (control, no block). Standard hypothesis tests (t test or Mann-Whitney U test, χ test) were performed to analyze baseline characteristics and outcome parameters. The primary end point of the study was total morphine (mg) consumption at 24 hours postoperatively. Serial total and free ropivacaine serum levels were determined in 10 patients. RESULTS: After obtaining ethical committee approval and written informed consent, 88 patients were included. Mean (SD) morphine consumption at 24 hours postoperatively was reduced in group FICB compared to group C: 10.25 (1.64) mg versus 19.0 (2.4) mg (P = 0.004). Using a mean dose of 2.6-mg/kg ropivacaine (range, 2-3.4 mg/kg), none of the patients had total or free ropivacaine levels above the maximum tolerated serum concentration. CONCLUSIONS: We conclude that a high-dose longitudinal supra-inguinal FICB reduces postoperative morphine requirements after anterior approach THA.Clinical Trials Registry: EU Clinical Trials Register. www.clinicaltrialsregister.eu #2014-002122-12.

Pneumoperitoneum Does Not Influence Spread of Local Anesthetics in Midaxillary Approach Transversus Abdominis Plane Block: A Descriptive Cadaver Study.

BACKGROUND AND OBJECTIVES: The transversus abdominis plane (TAP) block can be used as part of a multimodal analgesia protocol after abdominal surgery. This study investigated whether a pneumoperitoneum during abdominal surgery influences the spread of local anesthetics. METHODS: Nine fresh frozen cadavers were used for the study. Using an ultrasound-guided midaxillary technique, a unilateral TAP block-like injection with 20 mL of methylene blue dye was performed. After the injection, a pneumoperitoneum was immediately installed for 1 hour. After desufflation, this ipsilateral side was dissected, and a TAP block-like injection was performed on the contralateral side. One hour after injection, the contralateral side was also dissected. The anatomical dissection was used to determine the extent of dye spread and the nerves stained by the dye. RESULTS: In none of the specimens did the dye reach the posterior origin of the transverse abdominal muscle. There was no statistically significant difference in the number of stained nerves and spread of the dye in the insufflated side compared with the noninsufflated side. In 4 of 9 cadavers, we found a variant course of a nerve preventing staining of that nerve. CONCLUSIONS: The stretch of the abdominal wall caused by the insufflation of the abdomen does not influence the spread of dye in the abdominal wall. Because of the absence of posterior spread, regardless of the timing of a midaxillary ultrasound-guided approach, we believe that a posterior approach should be chosen if posterior spread is desired.

Speckle tracking for the intraoperative assessment of right ventricular function: a feasibility study.

OBJECTIVES: Speckle tracking is an ultrasound method that assesses B-mode features to measure tissue displacement and derive deformation parameters. The objective of this study was to assess the feasibility of using speckle tracking in the measurement of right ventricular (RV) longitudinal strain during cardiac surgery using transesophageal echocardiography (TEE). DESIGN: This was a prospective, observational cohort study. SETTING: A single university hospital setting. PARTICIPANTS: Twenty-one patients without valvular disease referred for coronary artery bypass graft surgery were studied. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: After the induction of anesthesia and mechanical ventilation, transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) were used to obtain tricuspid annular plane systolic excursion (TAPSE), RV fractional area of change (FAC), and 2-dimensional strain analysis (speckle tracking) on 3 consecutive heart beats. There was a larger percentage of measurable segments achieved when using TEE. All segments could be analyzed per cardiac cycle in 73% of loops when using TEE and 38% when using TTE. The global strain value was similar using both methods (TEE: -20.4%, TTE: -20.1%). The TAPSE could be measured in only 52% of the segments using TTE and 100% using TEE. The FAC could be measured in 90.5% of the loops using TEE and in only 33.3% of the loops using TTE. CONCLUSIONS: Perioperative measurements of RV strain using TEE in ventilated patients is feasible. The success rate was higher using TEE in ventilated patients under anesthesia. Differences between the 2 methods were likely the result of differences in 2-dimensional image quality.

Ventricular unloading with a miniature axial flow pump in combination with extracorporeal membrane oxygenation.

OBJECTIVE: ECMO for acute cardiorespiratory failure is an established therapeutic option. Persistent insufficient unloading of the left ventricle (LV) can compromise recovery of ventricular function. We decided to insert a miniature rotary blood pump (Impella) for decompression of the LV. In contrast to previous experience with this new device, where it was generally used for postcardiotomy heart failure or cardiogenic shock and inserted in the operating room or the catheter laboratory, this is the first report describing the potential of this technology in the intensive care unit, in a patient on ECMO and the value of echocardiography guidance. PATIENT: A 13-year-old boy with a history of congenital heart disease was admitted to the ICU with acute cardio-respiratory failure. INTERVENTIONS: On day 2 venoarterial ECMO was instituted because of worsening cardiorespiratory insufficiency refractory to conventional treatment. On day 5 a percutaneous rotary blood pump was inserted to decompress the LV. CONCLUSIONS: A percutaneous miniature rotary blood pump can be an alternative to decompress a failing LV in the setting of VA-ECMO. Echocardiography can avoid the use of fluoroscopy and the transport to a catheter laboratory to insert the rotary pump.