Optimizing the safety and practice of ultrasound-guided regional anesthesia: the role of echogenic technology.

PURPOSE OF REVIEW: Significant improvements have been made in the quality of ultrasound imaging, and it is now much easier to see nerves. However, the key to safe ultrasound-guided regional anesthesia is to be able to direct the needle to the target. This relies on good needle visibility. We review the recent advances that have been made in this crucial area. RECENT FINDINGS: Echogenic needles can improve shaft and tip visibility independent of experience level, compensate for suboptimal scanning technique, allow steeper insertion angles, reduce technical difficulty, and increase both confidence and satisfaction by anesthesiologists. An echogenic needle encourages holding the probe in one place on the patient, only advancing the needle when it can be seen, hence reducing the likelihood of quality-compromising behaviors. The poor visibility of nonechogenic needles when inserted at steeper angles commonly causes the observer to underestimate the insertion depth of the needle. Significant differences in echogenicity are found when comparing the currently available needles. SUMMARY: Good echogenic needles should increase safety, efficacy, and simplicity, and hopefully further drive the adoption of ultrasound-guided techniques, to the benefit of our patients.

Patient perceptions of regional anesthesia: influence of gender, recent anesthesia experience, and perioperative concerns.

BACKGROUND AND OBJECTIVES: Anesthesiologists often find that patients would prefer a general anesthetic (GA) to a regional anesthetic (RA) for surgery. We surveyed patients' attitudes to RA in an Australian tertiary-care hospital, hoping to understand the reasons for acceptance or refusal. We explored how 3 main factors influence the patient's choice for subsequent RA: gender, type of anesthetic on the day of surgery, and perioperative concerns. METHODS: Consecutive patients at a single institution were interviewed on the first postoperative day by a research nurse, either as a face-to-face interview or by telephone after ambulatory surgery. A short description of RA and GA was given, and preferences for future anesthesia and concerns were recorded. RESULTS: Complete data were obtained from 1000 patients. More women preferred GA compared with men (76.3% vs 69.0%). Patients who received only RA during their surgery on the previous day were almost 3 times more likely to express a future preference for RA compared with those who received any GA, using hypothetical examples of arm or hip surgery (83.2% vs 21.1%, P = 0.00001). Patients expressed more concerns about hearing or seeing the surgery than experiencing a complication, and 84% preferred sedation. CONCLUSIONS: More patients, especially females, may accept RA if reassured appropriately about not hearing or seeing the surgery. Once patients have experienced RA, they are more likely to choose it in future. Modification of our discussion and consent process may increase the uptake of RA techniques.

A review of the benefits and pitfalls of phantoms in ultrasound-guided regional anesthesia.

With the growth of ultrasound-guided regional anesthesia, so has the requirement for training tools to practice needle guidance skills and evaluate echogenic needles. Ethically, skills in ultrasound-guided needle placement should be gained in a phantom before performance of nerve blocks on patients in clinical practice. However, phantom technology is varied, and critical evaluation of the images is needed to understand their application to clinical use. Needle visibility depends on the echogenicity of the needle relative to the echogenicity of the tissue adjacent the needle. We demonstrate this point using images of echogenic and nonechogenic needles in 5 different phantoms at both shallow angles (20 degrees) and steep angles (45 degrees). The echogenicity of phantoms varies enormously, and this impacts on how needles are visualized. Water is anechoic, making all needles highly visible, but does not fix the needle to allow practice placement. Gelatin phantoms and Blue Phantoms provide tactile feedback but have very low background echogenicity, which greatly exaggerates needle visibility. This makes skill acquisition easier but can lead to false confidence in regard to clinical ability. Fresh-frozen cadavers retain much of the textural feel of live human tissue and are nearly as echogenic. Similar to clinical practice, this makes needles inserted at steep angles practically invisible, unless they are highly echogenic. This review describes the uses and pitfalls of phantoms that have been described or commercially produced.

Echogenic technology can improve needle visibility during ultrasound-guided regional anesthesia.

Needle tip visualization is fundamental to the safety and efficacy of ultrasound-guided regional anesthesia (UGRA). It can be extremely challenging especially at steep insertion angles. We assessed whether an echogenic needle improved tip visibility during UGRA by anesthesiologists performing their normal in-plane technique. The visibility of the Pajunk Sonoplex (echogenic) and the Pajunk Uniplex (control) needle were compared during 60 nerve blocks (30 femoral, 30 sciatic) in this randomized controlled trial. All ultrasound imaging was recorded for analysis. The anesthesiologist subjectively estimated the percentage time they had visualized the needle tip (5-point scale: 1 [0%-20%], 2 [20%-40%], 3 [40%-60%], 4 [60%-80%], 5 [80%-100%]). The actual time the tip was in view, angle of needle insertion, target depth, and procedure time were subsequently measured objectively by a single investigator. The Sonoplex group had both subjectively and objectively better tip visibility (P=0.002), despite having larger mean body mass index (29.0 vs 25.0 kg/m(2), P=0.01) and steeper mean insertion angle (31 vs 22 degrees, P=0.03). Objective percentage tip visibility, during in-plane UGRA, reduced by 12% for every 10-degree increase in insertion angle with the control. Tip visibility with the Sonoplex was independent of insertion angle over the range studied (0-57 degrees, P=0.95). This finding occurred when nonexpert anesthesiologists performed their standard UGRA technique. A needle that is visible for a greater percentage of time has potential safety and efficacy implications.

Sonographic identification of needle tip by specialists and novices: a blinded comparison of 5 regional block needles in fresh human cadavers.

BACKGROUND AND OBJECTIVES: Needle visibility using ultrasound remains problematic at steep insertion angles. Despite modified techniques, steep approaches are still needed, particularly in the obese, neuraxial anesthesia or pain blocks around the spine. We describe a novel technique for objective assessment of needle-tip identification and present data on a new needle. METHODS: Five needles were compared for accuracy of tip position identification. Pajunk facet-tipped, Tuohy-tipped, Polymedic Ultrasound, Hakko EchoStim, and a new intermittently textured needle (T). Static ultrasound images were obtained of the needles in first-thaw, unembalmed cadavers at shallow, moderate and steep angles. Actual tip position was defined. Images were presented in blinded, random order to 10 experienced and 10 novice anesthetists who estimated tip position. Distance between true tip position and estimated position was measured ("tip error"). Secondary objectives included subjective measures of visibility and differences between needles at shallower insertion angles and between novice and expert observers. RESULTS: At steep angles, study needles varied significantly with regard to tip error (P < 0.0001). Needle T scored highest for confidence and subjective visibility at moderate and steep angles. There was no significant difference between novice and experienced anesthetists for tip error or visibility. Experts were more confident in their estimates. CONCLUSIONS: Needle T demonstrated good properties even at steep insertion angles. Tip location was accurate, and observers rated it highly visible. Ability to identify needle-tip position can be objectively assessed.

Ketamine in chronic pain management: an evidence-based review.

Ketamine has diverse effects that may be of relevance to chronic pain including: N-methyl-D-aspartic acid, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, kainate, gamma-aminobutyric acid(A) receptors; inhibition of voltage gated Na(+) and K(+) channels and serotonin, dopamine re-uptake. Ketamine has been in clinical practice for over 30 yr; however, there has been little formal research on the effectiveness of ketamine for chronic pain management. In this review we evaluate the available clinical data as a basis for defining the potential use of ketamine for chronic pain. Literature referenced in this review was obtained from a computer search of EMBASE and MEDLINE from 1966 through August, 2002. Search terms included ketamine, ketalar, pain, painful, analgesic, and analgesia. Abstracts were screened for relevance and publications relating to chronic pain use were obtained. Levels of evidence were stratified according to accepted guidelines (level I-IV). For central pain, there is level II and level IV evidence of efficacy for parenteral and oral ketamine. For complex regional pain syndromes, there is only level IV evidence of efficacy of epidural ketamine. For fibromyalgia, there is level II evidence of pain relief, reduced tenderness at trigger points, and increased endurance. For ischemic pain, a level II study reported a potent dose-dependent analgesic effect, but with a narrow therapeutic window. For nonspecific neuropathic pain, level II and level IV studies reported divergent results with questionable long-term effects on pain. For phantom limb pain and postherpetic neuralgia, level II and level II studies provided objective evidence of reduced hyperpathia and pain relief was usually substantial either after parenteral or oral ketamine. Acute on chronic episodes of severe neuropathic pain represented the most frequent use of ketamine as a "third line analgesic," often by IV or subcutaneous infusion (level IV). In conclusion, the evidence for efficacy of ketamine for treatment of chronic pain is moderate to weak. However, in situations where standard analgesic options have failed ketamine is a reasonable "third line" option. Further controlled studies are needed.