Plexus and peripheral nerve block anaesthesia – A step beyond ultrasound or full circle?

Krol, A.; De Andres, J.
doi:10.1016/j.redar.2015.12.003
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    "titulo" => "Plexus and peripheral nerve block anaesthesia &#8211; A step beyond ultrasound or full circle&#63;"
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        "titulo" => "Anestesia con bloqueo nervioso perif&#233;rico y del plexo&#58; &#191;Un paso m&#225;s all&#225; de la ecograf&#237;a o el cierre del c&#237;rculo&#63;"
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          "en" => "<p id="spar0005" class="elsevierStyleSimplePara elsevierViewall">Ultrasound imaging of brachial plexus of patient with high BMI &#40;57&#41;&#46; &#40;A&#41; Interscalene block &#40;IB&#41;&#46; Trunks of brachial plexus in interscalene groove&#46; Identification of plexus looks more challenging than in average patient Ant &#8211; anterior&#44; Post &#8211; posterior&#44; AS &#8211; anterior scalene muscle&#44; MS &#8211; Middle scalene muscle&#46; Arrows point at the upper trunk&#46; &#40;B&#41; Supraclavicular block&#46; Identification of plexus division within a sheath was only possible after dynamic scanning more proximally&#46; Circle A &#8211; subclavian artery&#46; Circle B &#8211; brachial plexus&#46; Note white hyper echoic lines of the first rib and pleura&#46; &#40;C&#41; Infraclavicular block&#46; Probe position directly under clavicle with medial end in slightly caudal orientation to get transection of axillary artery and clear view of pleura&#46; A &#8211; axillary artery AV &#8211; axillary vein&#46; Dotted line delineates the pleura&#46; Arrow points at hypothetical position of brachial plexus cords &#8211; not visible&#46; Note maximum possible depth reached by linear high frequency probe 8&#8211;13<span class="elsevierStyleHsp" style=""></span>MHz&#46; Use of 5&#8211;8<span class="elsevierStyleHsp" style=""></span>MHz would be more appropriate&#46;</p>"
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    "textoCompleto" => "<span class="elsevierStyleSections"><p id="par0005" class="elsevierStylePara elsevierViewall">High resolution&#44; portable ultrasound has become bedside stethoscope of XXI century and undoubtedly brought a new dimension to regional anaesthesia and interventional pain management&#46; Since Kapral and colleagues publication<a class="elsevierStyleCrossRef" href="#bib0245"><span class="elsevierStyleSup">1</span></a> in 1994&#44; more than 20 years ago describing ultrasound guided supraclavicular brachial plexus block and sonographic imaging of stellate ganglion block published a year later<a class="elsevierStyleCrossRef" href="#bib0250"><span class="elsevierStyleSup">2</span></a> the number of publications has exploded&#46; Authors Pubmed search on 13&#47;10&#47;2015 and using following Boolean operators&#58; &#8220;ultrasound guided peripheral nerve block&#8221;&#44; and &#8220;ultrasound guided chronic pain blocks&#8221;&#44; revealed 1684 and 398 publications respectively&#46;<a class="elsevierStyleCrossRef" href="#bib0255"><span class="elsevierStyleSup">3</span></a> At the author institution&#44; St George&#39;s Hospital one of the largest hospitals in the UK in 2005 there were only one ultrasound system for vascular access not suitable for peripheral nerve block&#46; Ten years later for 30 operating theatres there is more than 12 systems some dedicated for exclusive use for subspecialty service such as&#58; chronic pain&#44; paediatric&#44; obstetric etc&#46; Intuitively we may say that seeing is believing and safety and efficacy of ultrasound application in contemporary regional anaesthesia practice is so obvious like a parachute in widely cited systematic review of randomised control trial of jumping out of the plane with and without parachute&#46;<a class="elsevierStyleCrossRef" href="#bib0260"><span class="elsevierStyleSup">4</span></a> However&#44; at least 4 cases of transient neurological deficits after ultrasound guided peripheral nerve blocks without nerve stimulator or injection pressure monitoring has been reported in our institution in 2015 only&#44; and required further imaging and follow up&#46;</p><p id="par0010" class="elsevierStylePara elsevierViewall">In this editorial authors has critically looked at ultrasound&#44; nerve stimulator and injection pressure monitoring as a tools complementing each other and perhaps likely to produce better outcome and further reduce the risk of complications&#46;</p><span id="sec0005" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0005">Evidence based medicine and ultrasound</span><p id="par0015" class="elsevierStylePara elsevierViewall">Systemic reviews has shown that ultrasound guided blocks are not inferior to other techniques&#44; have similar success rate&#44; need less time to perform&#44; have faster onset&#44; longer duration&#44; reduce volume of local anaesthetics and decreased risk of vascular puncture&#46;<a class="elsevierStyleCrossRefs" href="#bib0265"><span class="elsevierStyleSup">5&#44;6</span></a> Ultrasound guidance however has not been associated with reduce rate of long term peripheral nerve injury and reported data claim range from 1&#58;2500 to 1&#58;5000 for both pre and ultrasound era&#46;<a class="elsevierStyleCrossRefs" href="#bib0275"><span class="elsevierStyleSup">7&#44;8</span></a> There might be various speculations to explain the phenomenon&#46; Landmarks&#44; paresthesia&#44; nerve stimulator techniques had been used by a narrow group of expert in the field and with increased ultrasound accessibility total number of performed blocks has risen significantly&#46; Therefore the same number of complications&#44; in fact indicates decrease in advert outcome&#46; Similarly fellowships in regional anaesthesia have become popular and numerous training centres offer such an opportunity&#46; Guidelines and recommendations for fellowship training in regional anaesthesia already exist<a class="elsevierStyleCrossRef" href="#bib0285"><span class="elsevierStyleSup">9</span></a> but with increased number of inexperienced hands the potential risk of complications could increase&#46; Clearly it is not the case confirming adequate supervision has been provided in teaching centres&#46;</p><p id="par0020" class="elsevierStylePara elsevierViewall">Although&#44; systems of reporting complications has become much easier and simplified with instant online access&#44; registry governed by regional anaesthesia national societies are not yet available worldwide&#46; Complications of plexus and peripheral nerve blocks have been rare events and we learn more from the case reports and case series than from randomised control trials&#46;</p><p id="par0025" class="elsevierStylePara elsevierViewall">In a search to improve a decision making process to justify some medical treatment and refute other the concept of evidence based medicine has been introduced by a group from McMaster University in Hamilton&#44; Ontario&#46;<a class="elsevierStyleCrossRefs" href="#bib0290"><span class="elsevierStyleSup">10&#44;11</span></a> They proposed the hierarchy of evidence with systematic review of randomised trials being on top and expert opinion and observation at the bottom&#46; RCT&#39;s have become a powerful tool&#44; medical writing has become a profession&#44; statistical techniques and jargon has become the base of academic career&#46; But even the creator of randomised trials&#44; the English statistician Sir Austin Bradford Hill had said&#58; &#8220;Any belief that the randomised controlled trial is the only way would mean not that the pendulum had swung too far but that it had come right off the hook&#8221;&#46;<a class="elsevierStyleCrossRef" href="#bib0295"><span class="elsevierStyleSup">11</span></a> Simple common sense and daily clinical practice incline to use US but proving that ultrasound guided regional anaesthesia is superior and safer than nerve stimulator or even paresthesia might be extremely difficult as statistical tests will struggle to detect difference due to such a rare occurrence of nerve injury &#8211; 1&#58;2500&#46; Editorialists with grey hair calculated that more than 70&#44;000 per group would be required to prove a 50&#37; reduction in such an incidence &#8211; a study rather unlikely to be conducted&#46;<a class="elsevierStyleCrossRef" href="#bib0300"><span class="elsevierStyleSup">12</span></a></p></span><span id="sec0010" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0010">Limitations of ultrasound</span><p id="par0030" class="elsevierStylePara elsevierViewall">Even if perfect technique and training existed there would be obstacles related to limitations of ultrasound physics as well as patient anatomy and targeted structures&#46; Some neural structures can be identified easily regardless of body habits and others not&#46;</p><p id="par0035" class="elsevierStylePara elsevierViewall">Over the last decade enormous progress in ultrasound technology has been observed&#46; The resolution of systems has increased&#44; ultrasound systems have become portable and affordable&#46; However the trend to increase resolution to improve picture quality has its price&#46; Ultrasound waves travel through tissues in different speed&#58; 1450<span class="elsevierStyleHsp" style=""></span>m&#47;s in fat&#44; 1575<span class="elsevierStyleHsp" style=""></span>m&#47;s in muscles and blood tissues&#44; 2800<span class="elsevierStyleHsp" style=""></span>m&#47;s in bone and 380<span class="elsevierStyleHsp" style=""></span>m&#47;s in air&#46; US waves are transmitted to deeper structures but at the cost of loss of acoustic energy &#8211; attenuation&#44; transformation to heat&#44; refraction &#40;change of direction after passing through structures of different speeds of sound transmission&#41;&#44; scattering &#40;whenever hitting small or irregular object of different acoustic impedance&#41; and the most important reflected back to the transducer as an echo&#46; The intensity of reflected echo is proportional to the difference of acoustic impedance between two media sound wave travels through&#46; Acoustic impedance is an important ultrasound property of any material or tissue&#44; and is the product of the density and the sound velocity in the material&#44; expressed in units called the Rayl&#46; Acoustic impedance in &#40;10<span class="elsevierStyleSup">6</span><span class="elsevierStyleHsp" style=""></span>Rayls&#41; of bone&#44; muscle&#44; fat&#44; lung and air is 7&#46;8&#44; 1&#46;71&#44; 1&#46;34&#44; 0&#46;18&#44; and 0&#46;0004 respectively&#46; The wavelength and frequency are inversely related as per simple equation <span class="elsevierStyleItalic">C</span><span class="elsevierStyleHsp" style=""></span>&#61;<span class="elsevierStyleHsp" style=""></span>frequency<span class="elsevierStyleHsp" style=""></span>&#215;<span class="elsevierStyleHsp" style=""></span>wavelength&#46; The higher the frequency &#40;short wavelength&#41; the better resolution which is ability to distinguish one object from another&#46; High frequency transducers &#40;8&#8211;13<span class="elsevierStyleHsp" style=""></span>MHz&#41; are not able to reflect good image at depth more than 4&#8211;6<span class="elsevierStyleHsp" style=""></span>cm therefore in any case of target lying deeper as it is often in obese patients lower frequency transducer should be used at cost of ability to distinguish details such as intra or extraneural needle position&#46; Is there anything else but depth and frequency in getting good quality ultrasound imaging&#63; Adipose tissues have nonlinear relationship to frequency resulting in exaggerated attenuation&#46; Due to uneven speed of sound in irregularly shaped adipose layers phase aberration occurs&#46;<a class="elsevierStyleCrossRefs" href="#bib0305"><span class="elsevierStyleSup">13&#44;14</span></a> Marhofer and colleagues<a class="elsevierStyleCrossRef" href="#bib0315"><span class="elsevierStyleSup">15</span></a> designed feasibility study to help more systematic&#44; objective comparison of nerve structure&#46; The visibility of nerve depends on interface with surrounding tissues as difference in acoustic impedance determines reflection and grey-scale histogram on US machine screen&#46; They performed a prospective&#44; comparative&#44; blinded study to quantify nerve visibility differences in obese versus normal-weight patients&#46; 40 female patients were included in the study&#44; 20 in normal-weight group BMI 22 &#40;18&#8211;24&#41; and 20 obese BMI 40 &#40;31&#8211;57&#41;&#46; Median nerve at the mid-third of the forearm between the superficial and profound flexor digitorum muscle and sciatic nerve at the mid-femoral level between the biceps femoris&#44; semitendinosus&#47;semimembranosus and adductor muscles were identified and assessed&#46; The depth&#44; circumference and cross-sectional area &#40;CSA&#41; recorded&#46; Not surprisingly both nerves were located deeper in obese group but nerves diameter and CSA were similar in both groups&#46; Histogram grey-scale difference between median nerve and surrounding tissue in both group were similar&#44; whereas surrounding tissues around sciatic nerve displayed significant higher values in obese group making sciatic nerve significantly less visible&#46; Although use the histogram grey-scale to quantify US picture has been described previously this is the first description addressing peripheral nerve visibility&#46; More difficult visualisation of targeted structures in obese patients has been confirmed in clinical practice especially in regards of plexus anaesthesia&#58; interscalene block &#40;ISB&#41;&#44; supraclavicular &#40;SCB&#41;&#44; infraclavicular &#40;ICB&#41;&#44; sacral plexus &#40;SP&#41;&#44; fascial plane blocks with some examples shown in <a class="elsevierStyleCrossRef" href="#fig0005">Figure 1</a>&#46;<a class="elsevierStyleCrossRef" href="#bib0320"><span class="elsevierStyleSup">16</span></a></p><elsevierMultimedia ident="fig0005"></elsevierMultimedia><p id="par0040" class="elsevierStylePara elsevierViewall">In optimisation of ultrasound pictures following factors are to be taken into consideration&#46; The abilities of operator&#44; patient&#44; ultrasound system settings and needle visibility enhancement&#46; The first two has been discussed already&#46; The tips on pictures optimisation and basic US physics have been described in every recently published regional anaesthesia manuals&#46;<a class="elsevierStyleCrossRefs" href="#bib0325"><span class="elsevierStyleSup">17&#44;18</span></a> Choice of transducer frequency&#44; depth&#44; focus&#44; gain&#44; time gain compensation &#40;TGC&#41; has become bread and butter in daily anaesthetists practice&#46; The newer technical developments such as Compound Imaging and Tissue Harmonic has been built in many US systems&#46; For the former transducer emit ultrasound waves at different angles and then collected echoes are combined to produce a single higher quality image and reduce artefacts&#46; For the latter transducer selectively captures higher frequency echoes and in result produce better picture resolution and less artefacts such as phase aberration caused by fat tissue&#46;</p><p id="par0045" class="elsevierStylePara elsevierViewall">Obtaining simultaneous view of targeted structure as well as approaching needle often become challenging&#46; For shallow structures needle direction is almost perpendicular to US beam resulting in specular reflection and almost mirror view as long as needle is hold within 1<span class="elsevierStyleHsp" style=""></span>mm wide ultrasound beam&#46; For deeper structures echogenic needle proved to make a difference and newer ultrasound machines have various software&#39;s such as beam steering and other navigation systems to reduce scattering and increase needle visibility&#46;<a class="elsevierStyleCrossRefs" href="#bib0335"><span class="elsevierStyleSup">19&#8211;21</span></a> However&#44; operator has to be aware of the system capability and additional training is required to efficiently operate the software to optimise image&#46;</p><p id="par0050" class="elsevierStylePara elsevierViewall">It has become clear that despite of our anatomical knowledge&#44; in depth training&#44; supervision&#44; high resolution ultrasound images there are limitation related to human error&#44; anatomical variation as well as ultrasound physics&#46; Krediet and colleagues injected 0&#46;5<span class="elsevierStyleHsp" style=""></span>ml of dye extraneurally and intraneurally in cadavers imitating subgluteal sciatic nerve block&#46; Ultrasound video clips were reviewed by experts and novices&#46; Although recognition of extraneural injections was almost perfect in both groups&#44; 20&#8211;50&#37; of intraneural injections were overlooked in the novice group and 1 in 6 injection in expert group&#46;<a class="elsevierStyleCrossRef" href="#bib0335"><span class="elsevierStyleSup">19</span></a></p></span><span id="sec0015" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0015">Is your nerve stimulator still around&#63;</span><p id="par0055" class="elsevierStylePara elsevierViewall">As our vision might not be as sharp as we think<a class="elsevierStyleCrossRef" href="#bib0300"><span class="elsevierStyleSup">12</span></a> how we can in relatively simple way further reduce the complications&#44; especially intraneural injection and the risk of fascicular damage with persisting neurological deficits&#63; At the bottom drawer of almost every anaesthetic machine perhaps covered by dust and old anaesthetic charts lies nerve stimulator&#46; Not only grey haired but also bald ones still remember the exciting time when small box has appeared in anaesthetic rooms and has changed our practice forever following Montgomery and Raj describing the technique of nerve localisation using small&#44; portable battery generated nerve stimulator<a class="elsevierStyleCrossRef" href="#bib0340"><span class="elsevierStyleSup">20</span></a> Coulombs law describes the relationships between the minimal current required to elicit response and the distance from the nerve&#58; <span class="elsevierStyleItalic">E</span><span class="elsevierStyleHsp" style=""></span>&#61;<span class="elsevierStyleHsp" style=""></span><span class="elsevierStyleItalic">K</span> &#40;<span class="elsevierStyleItalic">Q</span>&#47;<span class="elsevierStyleItalic">r</span><span class="elsevierStyleSup">2</span>&#41; where <span class="elsevierStyleItalic">E</span> is current required&#44; <span class="elsevierStyleItalic">K</span> is a constant&#44; <span class="elsevierStyleItalic">Q</span> is minimal current&#44; <span class="elsevierStyleItalic">r</span> is the distance&#46; Although concept very attractive and simple soon has become apparent that current&#8211;distance relationship could not so easy be translated due to complexity of biological environment&#46; Needle isolation&#44; impedance of surrounding tissue&#44; motor and sensory neurons organisation within a fascicle&#44; short pulse width &#60;100<span class="elsevierStyleHsp" style=""></span>&#956;s necessary for activation of large A-Alpha motor fibres&#44; longer &#62;300<span class="elsevierStyleHsp" style=""></span>&#956;s to activate smaller&#44; sensory A-delta and C fibres are only few examples of complex interaction&#46; Nevertheless nerve stimulator has become ever present device for nerve location and motor response at 0&#46;5<span class="elsevierStyleHsp" style=""></span>mA and less considered satisfactory and indicating needle-nerve distance of 5<span class="elsevierStyleHsp" style=""></span>mm or less&#46;<a class="elsevierStyleCrossRefs" href="#bib0345"><span class="elsevierStyleSup">21&#44;22</span></a> Steinfeldt and colleagues<a class="elsevierStyleCrossRef" href="#bib0355"><span class="elsevierStyleSup">23</span></a> in animal studies using anaesthetised pigs performed 235 brachial plexus and femoral nerves localisation using low stimulating current threshold &#40;SCT&#41; &#8211; 0&#46;01&#8211;0&#46;3<span class="elsevierStyleHsp" style=""></span>mA or high SCT &#8211; 0&#46;8&#8211;1&#46;0<span class="elsevierStyleHsp" style=""></span>mA and 1&#46;8&#8211;2&#46;0<span class="elsevierStyleHsp" style=""></span>mA SCT as a control&#46; As low as 0&#46;3<span class="elsevierStyleHsp" style=""></span>ml of dye was injected after satisfactory stimulation followed by anatomical dissection&#46; For both high and low SCT dye spread was close to epineurium to provide clinical effect&#46; Almost 50&#37; injection in control group &#40;SCT 1&#46;8&#8211;2&#46;0<span class="elsevierStyleHsp" style=""></span>mA&#41; were out of range and distal to nerve epineurium&#46; Conclusion of these valuable studies would be another confirmation of Coulombs law with a wider range of stimulating current and higher SCT as an end point&#46; Intraneural injection appeared in 3 out of 235 &#40;1&#46;3&#37;&#41; punctures&#44; two in high SCT group and one in low SCT group&#46; High hopes of nerve stimulator as a sole instrument in nerve localisation to increase block reliability and reduce incidence of neurological complications has not been proven due to the complex interactions highlighted&#44; however the clinical value of the little device has been defended and nerve stimulator has become and likely to stay widely use alone or in combination with ultrasound&#46;<a class="elsevierStyleCrossRefs" href="#bib0360"><span class="elsevierStyleSup">24&#8211;26</span></a> In a new brave era of ultrasound clinical discovery that needle-nerve distance is not easy translated to motor response and observation that intraneural needle placement often fails to provoke motor response highlighted lack of nerve stimulator sensitivity and stipulated plethora of publications&#46;<a class="elsevierStyleCrossRefs" href="#bib0375"><span class="elsevierStyleSup">27&#8211;29</span></a> However enough animal and human data exists by now to say that motor response at current 0&#46;2<span class="elsevierStyleHsp" style=""></span>mA or less has been associated with intraneural needle placement or at least with direct needle-nerve contact&#46;<a class="elsevierStyleCrossRef" href="#bib0390"><span class="elsevierStyleSup">30</span></a> It has been demonstrated by Voelckel and colleagues that inflammatory changes occurred in 50&#37; of pig sciatic nerve block with bupivacaine if motor response was evoked at current 0&#46;2<span class="elsevierStyleHsp" style=""></span>mA or less&#46; No histological changes were observed at current between 0&#46;3 and 0&#46;5<span class="elsevierStyleHsp" style=""></span>mA&#46;<a class="elsevierStyleCrossRef" href="#bib0395"><span class="elsevierStyleSup">31</span></a> Tsai and colleagues studying as well pigs sciatic nerve response to stimulation in relation to needle to nerve distance showed that motor response at stimulation of current of 0&#46;2<span class="elsevierStyleHsp" style=""></span>mA and less was consistent and specific for intraneural needle placement&#46; They confirmed also lack of sensitivity of nerve stimulation demonstrating lack of motor response almost up to 2<span class="elsevierStyleHsp" style=""></span>mA despite of intraneural needle placement&#46;<a class="elsevierStyleCrossRef" href="#bib0400"><span class="elsevierStyleSup">32</span></a> Human data from Bigeleisen and colleagues experiment with supraclavicular brachial plexus block showed that motor response at 0&#46;2<span class="elsevierStyleHsp" style=""></span>mA and less could only be demonstrated when needle were through brachial plexus sheath in direct contact of divisions of the plexus&#46;<a class="elsevierStyleCrossRef" href="#bib0405"><span class="elsevierStyleSup">33</span></a></p><p id="par0060" class="elsevierStylePara elsevierViewall">Combination of at least two modalities&#58; ultrasound and nerve stimulator&#44; so called dual guidance has been advocated by experts in the field<a class="elsevierStyleCrossRefs" href="#bib0300"><span class="elsevierStyleSup">12&#44;34</span></a> Vassiliou and colleagues<a class="elsevierStyleCrossRef" href="#bib0370"><span class="elsevierStyleSup">26</span></a> demonstrated in animal studies after 235 punctures in 16 anaesthetised pigs that dual guidance ultrasound and nerve stimulator &#40;USNST&#41; were superior to nerve stimulator &#40;NS&#41; and ultrasound &#40;US&#41; alone in respect of nerve localisation 98&#46;5&#37;&#44; 90&#46;1&#37; and 81&#46;6&#37; respectively&#44; intraneural needle placement 0&#46;5&#37; of USNST&#44; 2&#46;5&#37; in NS&#44; 4&#37; US and inadvertent haematoma&#58; 1&#46;5&#37; in USNS group&#44; 2&#46;5&#37; in US group and as much as 10&#46;8&#37; in NS group&#46; Subsequently Orebaugh and colleagues shown that dual guidance reduced time for performing peripheral block in residents training programme&#46;<a class="elsevierStyleCrossRef" href="#bib0415"><span class="elsevierStyleSup">35</span></a></p></span><span id="sec0020" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0020">Opening injection pressure &#8211; watch out&#63;</span><p id="par0065" class="elsevierStylePara elsevierViewall">Concept of injection pressure monitoring has been around for some time and could be another safety factor easily introduced to the wide clinical practice&#46; Selander and Sjostrand as early as 1978 seeking for explanation of inadvertent spinal anaesthesia following sciatic nerve block in rats found it most likely to happen after intraneural needle placement and was associated with high injection pressure&#46;<a class="elsevierStyleCrossRef" href="#bib0420"><span class="elsevierStyleSup">36</span></a> For some reason the finding caused little echo in regional community until 26 years later Hadzic and colleagues demonstrated in dog&#39;s sciatic nerve model that perineural injection produced low injection pressure &#60;4<span class="elsevierStyleHsp" style=""></span>psi but intraneural&#44; intrafascicular injection were associated with high &#62;25<span class="elsevierStyleHsp" style=""></span>psi and corresponded with clinical and histological nerve injury&#46;<a class="elsevierStyleCrossRef" href="#bib0425"><span class="elsevierStyleSup">37</span></a> In the contrary another animal study on median nerve in pigs conducted by Lupu<a class="elsevierStyleCrossRef" href="#bib0430"><span class="elsevierStyleSup">38</span></a> and colleagues as well as Altermatt<a class="elsevierStyleCrossRef" href="#bib0435"><span class="elsevierStyleSup">39</span></a> and colleagues on porcine femoral nerve and brachial plexus were not able to show association with high injection pressure and evidence of nerve injury&#46; Importantly pressure recording was not a primary goal of investigation but ultrasonographic appearance of intraneural injection and visible nerve expansion which together with study methodology may explain the findings&#46;</p><p id="par0070" class="elsevierStylePara elsevierViewall">The only two human tissue cadaveric study were conducted by Orebaugh<a class="elsevierStyleCrossRef" href="#bib0440"><span class="elsevierStyleSup">40</span></a> and colleagues and the authors of this editorial&#46;<a class="elsevierStyleCrossRef" href="#bib0445"><span class="elsevierStyleSup">41</span></a> In the former 8 brachial plexus roots in unembalmed cadavers were injected and injection pressure and spread of mixture of local anaesthetic recorded&#46; The mean injection pressure were 48&#46;9<span class="elsevierStyleHsp" style=""></span>psi and in 1 out of 8 cases epidural spread were noted&#46; In the latter opening injection pressure were the primary objective of the study and small volume of 1<span class="elsevierStyleHsp" style=""></span>ml NaCl over relatively long period of 10<span class="elsevierStyleHsp" style=""></span>s were instilled to clearly identified on ultrasound median&#44; radial and ulnar nerve&#44; perineurally and intraneurally&#46; Intraneural injection produced significantly greater pressure than perineural injection did&#46;</p><p id="par0075" class="elsevierStylePara elsevierViewall">Methodological difference may explain the results of some of previous animal studies&#46;<a class="elsevierStyleCrossRefs" href="#bib0430"><span class="elsevierStyleSup">38&#44;39</span></a> Opening pressure to start the flow is giving feedback about a pressure needed to initiate injection but once the process is initiated recorded pressure will be affected by the rate of injection&#44; needle and syringe size and with large volume&#44; leakage of fluid once the barrier is broken&#46; False positive reading occurs even when injecting into non resisting compartment and rate of injection should be no more than 0&#46;3<span class="elsevierStyleHsp" style=""></span>ml&#47;s &#40;18<span class="elsevierStyleHsp" style=""></span>ml&#47;min&#41; to avoid an error&#46;<a class="elsevierStyleCrossRef" href="#bib0450"><span class="elsevierStyleSup">42</span></a> Even with extraneural needle position high injection pressure created by high flow rate might be a source of adverse outcome especially for plexus anaesthesia such as interscalene block&#44; lumbar plexus block or transforaminal nerve root block injections&#46; Gadsen and colleagues demonstrated in a clinical study of lumbar plexus block that high injection pressure &#40;&#62;20<span class="elsevierStyleHsp" style=""></span>psi&#41; resulted in contralateral spread and epidural block in 50&#37; of cases&#46;<a class="elsevierStyleCrossRef" href="#bib0455"><span class="elsevierStyleSup">43</span></a></p><p id="par0080" class="elsevierStylePara elsevierViewall">We have learned already that subjective individual feeling is not reliable enough to determine injection pressure&#46; In one study although anesthesiologists perceived an increase in the force required to inject&#44; 70&#37; used the pressure greater than 20<span class="elsevierStyleHsp" style=""></span>psi&#44;<a class="elsevierStyleCrossRef" href="#bib0460"><span class="elsevierStyleSup">44</span></a> in another only 30&#37; of anaesthesiologists rightly recognised intraneural needle position by syringe feel in provided animal model&#46;<a class="elsevierStyleCrossRef" href="#bib0465"><span class="elsevierStyleSup">45</span></a> There were few concepts how to more objectively measure injections pressure&#44; one to use standard syringe driver&#44;<a class="elsevierStyleCrossRef" href="#bib0470"><span class="elsevierStyleSup">46</span></a> another to use compressed air in the syringe&#46;<a class="elsevierStyleCrossRef" href="#bib0475"><span class="elsevierStyleSup">47</span></a></p><p id="par0085" class="elsevierStylePara elsevierViewall">In a busy clinical practice any additional piece of equipment&#44; set up will cost time and require training&#46; If pressure monitoring is to be adopted into wide clinical practice similar to nerve stimulator or ultrasound&#44; the device should be easy to use&#44; portable&#44; reliable&#44; and affordable&#46; Time will show if any device fulfil the criteria and get clinicians approval&#46;<a class="elsevierStyleCrossRef" href="#bib0480"><span class="elsevierStyleSup">48</span></a></p><p id="par0090" class="elsevierStylePara elsevierViewall">Regional anaesthesia effectiveness as well as minimal complication rate might be built like a ladder of safety&#46; It should include excellent in depth anatomical knowledge and no procedure to be undertaken before refreshed anatomy of surrounding structures&#46; Review of pre-procedure scans in chronic pain and scout scanning before regional anaesthesia block would be an example of good practice&#46; Patient vigilance would feedback in case of needle misplacement but might not always be possible nor appropriate&#46; Ultrasound guidance has become benchmark of our practice and has encouraged more anaesthesiologists to introduce regional blocks to their daily armamentarium but additional information from nerve stimulator can be invaluable specifically in situation of anatomical obstacles due to swelling&#44; haematoma&#44; obesity or simply plexus anaesthesia where US is not able to distinguish clearly neural structures&#46; Motor response at 0&#46;2<span class="elsevierStyleHsp" style=""></span>mA&#44; inevitably indicates intraneural needle placement and response at 1<span class="elsevierStyleHsp" style=""></span>mA would be sufficient for effective block&#46; It would be up to an individual what range to apply and advice might be a dangerous gift but meticulous documentation is paramount&#46; Injection pressure monitoring may prove to be useful as high injection pressure &#62;15<span class="elsevierStyleHsp" style=""></span>psi amongst other causes of injection to confined compartment may indicate intraneural needle placement or at least contact with epineurium&#46; Keeping injection pressure below 15<span class="elsevierStyleHsp" style=""></span>psi may prevent too rapid injection and its consequences such as uncontrolled spread into epidural space example being interscalene&#44; lumbar plexus and transforaminal injections&#46; Injection to perineural tissue &#40;outside epineurium&#41; produce low pressure and no clinical complications have been reported with low injection pressure&#46; Clinical wisdom suggests to apply available modalities at once as we do in general anaesthesia gathering various clinical information from tissue colour to calculation of oxygen delivery&#46; Triple monitoring seems to be easy enough to set up in daily clinical practice and none of the three alone can stand in complex biological interactions&#46;</p></span><span id="sec0025" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0025">Conflict of interest</span><p id="par0095" class="elsevierStylePara elsevierViewall">The authors declare no conflict of interest&#46;</p></span></span>"
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          "identificador" => "sec0005"
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          "en" => "<p id="spar0005" class="elsevierStyleSimplePara elsevierViewall">Ultrasound imaging of brachial plexus of patient with high BMI &#40;57&#41;&#46; &#40;A&#41; Interscalene block &#40;IB&#41;&#46; Trunks of brachial plexus in interscalene groove&#46; Identification of plexus looks more challenging than in average patient Ant &#8211; anterior&#44; Post &#8211; posterior&#44; AS &#8211; anterior scalene muscle&#44; MS &#8211; Middle scalene muscle&#46; Arrows point at the upper trunk&#46; &#40;B&#41; Supraclavicular block&#46; Identification of plexus division within a sheath was only possible after dynamic scanning more proximally&#46; Circle A &#8211; subclavian artery&#46; Circle B &#8211; brachial plexus&#46; Note white hyper echoic lines of the first rib and pleura&#46; &#40;C&#41; Infraclavicular block&#46; Probe position directly under clavicle with medial end in slightly caudal orientation to get transection of axillary artery and clear view of pleura&#46; A &#8211; axillary artery AV &#8211; axillary vein&#46; Dotted line delineates the pleura&#46; Arrow points at hypothetical position of brachial plexus cords &#8211; not visible&#46; Note maximum possible depth reached by linear high frequency probe 8&#8211;13<span class="elsevierStyleHsp" style=""></span>MHz&#46; Use of 5&#8211;8<span class="elsevierStyleHsp" style=""></span>MHz would be more appropriate&#46;</p>"
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      "titulo" => "References"
      "seccion" => array:1 [
        0 => array:2 [
          "identificador" => "bibs0005"
          "bibliografiaReferencia" => array:48 [
            0 => array:3 [
              "identificador" => "bib0245"
              "etiqueta" => "1"
              "referencia" => array:1 [
                0 => array:2 [
                  "contribucion" => array:1 [
                    0 => array:2 [
                      "titulo" => "Ultrasound guided supraclavicular approach for regional anesthesia of the brachial plexus"
                      "autores" => array:1 [
                        0 => array:2 [
                          "etal" => false
                          "autores" => array:6 [
                            0 => "S&#46; Kapral"
                            1 => "P&#46; Krafft"
                            2 => "K&#46; Eibenberger"
                            3 => "R&#46; Fitzgerald"
                            4 => "M&#46; Gosch"
                            5 => "C&#46; Weinstabl"
                          ]
                        ]
                      ]
                    ]
                  ]
                  "host" => array:1 [
                    0 => array:1 [
                      "Revista" => array:6 [
                        "tituloSerie" => "Anesth Analg"
                        "fecha" => "1994"
                        "volumen" => "78"
                        "paginaInicial" => "507"
                        "paginaFinal" => "513"
                        "link" => array:1 [
                          0 => array:2 [
                            "url" => "https://www.ncbi.nlm.nih.gov/pubmed/8109769"
                            "web" => "Medline"
                          ]
                        ]
                      ]
                    ]
                  ]
                ]
              ]
            ]
            1 => array:3 [
              "identificador" => "bib0250"
              "etiqueta" => "2"
              "referencia" => array:1 [
                0 => array:2 [
                  "contribucion" => array:1 [
                    0 => array:2 [
                      "titulo" => "Ultrasound imaging for stellate ganglion block&#46; Direct visualization of puncture site and local anaesthetic spread"
                      "autores" => array:1 [
                        0 => array:2 [
                          "etal" => false
                          "autores" => array:5 [
                            0 => "S&#46; Kapral"
                            1 => "P&#46; Krafft"
                            2 => "M&#46; Gosch"
                            3 => "D&#46; Fleishmann"
                            4 => "C&#46; Weinstabl"
                          ]
                        ]
                      ]
                    ]
                  ]
                  "host" => array:1 [
                    0 => array:1 [
                      "Revista" => array:6 [
                        "tituloSerie" => "Reg Anesth"
                        "fecha" => "1995"
                        "volumen" => "20"
                        "paginaInicial" => "323"
                        "paginaFinal" => "328"
                        "link" => array:1 [
                          0 => array:2 [
                            "url" => "https://www.ncbi.nlm.nih.gov/pubmed/7577781"
                            "web" => "Medline"
                          ]
                        ]
                      ]
                    ]
                  ]
                ]
              ]
            ]
            2 => array:3 [
              "identificador" => "bib0255"
              "etiqueta" => "3"
              "referencia" => array:1 [
                0 => array:1 [
                  "referenciaCompleta" => "<a id="intr0005" class="elsevierStyleInterRef" href="http://www.ncbi.nlm.nih.gov/pubmed/">www&#46;ncbi&#46;nlm&#46;nih&#46;gov&#47;pubmed&#47;</a> &#91;accessed on 13&#46;10&#46;15&#93;&#46;"
                ]
              ]
            ]
            3 => array:3 [
              "identificador" => "bib0260"
              "etiqueta" => "4"
              "referencia" => array:1 [
                0 => array:2 [
                  "contribucion" => array:1 [
                    0 => array:2 [
                      "titulo" => "Parachute use to prevent death and major trauma related to gravitational challenge&#58; systematic review of randomised controlled trials"
                      "autores" => array:1 [
                        0 => array:2 [
                          "etal" => false
                          "autores" => array:2 [
                            0 => "G&#46;C&#46;S&#46; Smith"
                            1 => "J&#46;P&#46; Pell"
                          ]
                        ]
                      ]
                    ]
                  ]
                  "host" => array:1 [
                    0 => array:1 [
                      "Revista" => array:5 [
                        "tituloSerie" => "Br Med J"
                        "fecha" => "2003"
                        "volumen" => "327"
                        "paginaInicial" => "1459"
                        "paginaFinal" => "1461"
                      ]
                    ]
                  ]
                ]
              ]
            ]
            4 => array:3 [
              "identificador" => "bib0265"
              "etiqueta" => "5"
              "referencia" => array:1 [
                0 => array:2 [
                  "contribucion" => array:1 [
                    0 => array:2 [
                      "titulo" => "Ultrasound guidance compared with electrical neurostimulation for peripheral nerve block&#58; a systematic review and meta-analysis of randomized controlled trials"
                      "autores" => array:1 [
                        0 => array:2 [
                          "etal" => false
                          "autores" => array:4 [
                            0 => "M&#46;S&#46; Abrahams"
                            1 => "M&#46;F&#46; Aziz"
                            2 => "R&#46;F&#46; Fu"
                            3 => "J&#46;L&#46; Horn"
                          ]
                        ]
                      ]
                    ]
                  ]
                  "host" => array:1 [
                    0 => array:2 [
                      "doi" => "10.1093/bja/aen384"
                      "Revista" => array:6 [
                        "tituloSerie" => "Br J Anaesth"
                        "fecha" => "2009"
                        "volumen" => "102"
                        "paginaInicial" => "408"
                        "paginaFinal" => "417"
                        "link" => array:1 [
                          0 => array:2 [
                            "url" => "https://www.ncbi.nlm.nih.gov/pubmed/19174373"
                            "web" => "Medline"
                          ]
                        ]
                      ]
                    ]
                  ]
                ]
              ]
            ]
            5 => array:3 [
              "identificador" => "bib0270"
              "etiqueta" => "6"
              "referencia" => array:1 [
                0 => array:2 [
                  "contribucion" => array:1 [
                    0 => array:2 [
                      "titulo" => "Ultrasound-guided regional anesthesia and analgesia&#58; a qualitative systematic review"
                      "autores" => array:1 [
                        0 => array:2 [
                          "etal" => false
                          "autores" => array:3 [
                            0 => "S&#46;S&#46; Liu"
                            1 => "J&#46;E&#46; Ngeow"
                            2 => "J&#46;T&#46; Yadeau"
                          ]
                        ]
                      ]
                    ]
                  ]
                  "host" => array:1 [
                    0 => array:2 [
                      "doi" => "10.1097/AAP.0b013e3181933ec3"
                      "Revista" => array:6 [
                        "tituloSerie" => "Reg Anesth Pain Med"
                        "fecha" => "2009"
                        "volumen" => "34"
                        "paginaInicial" => "47"
                        "paginaFinal" => "59"
                        "link" => array:1 [
                          0 => array:2 [
                            "url" => "https://www.ncbi.nlm.nih.gov/pubmed/19258988"
                            "web" => "Medline"
                          ]
                        ]
                      ]
                    ]
                  ]
                ]
              ]
            ]
            6 => array:3 [
              "identificador" => "bib0275"
              "etiqueta" => "7"
              "referencia" => array:1 [
                0 => array:2 [
                  "contribucion" => array:1 [
                    0 => array:2 [
                      "titulo" => "Ultrasound-guided regional anesthesia and patient safety&#58; an evidence-based analysis"
                      "autores" => array:1 [
                        0 => array:2 [
                          "etal" => false
                          "autores" => array:1 [
                            0 => "J&#46;M&#46; Neal"
                          ]
                        ]
                      ]
                    ]
                  ]
                  "host" => array:1 [
                    0 => array:2 [
                      "doi" => "10.1097/AAP.0b013e3181ccbc96"
                      "Revista" => array:6 [
                        "tituloSerie" => "Reg Anesth Pain Med"
                        "fecha" => "2010"
                        "volumen" => "35"
                        "paginaInicial" => "S59"
                        "paginaFinal" => "S67"
                        "link" => array:1 [
                          0 => array:2 [
                            "url" => "https://www.ncbi.nlm.nih.gov/pubmed/20216027"
                            "web" => "Medline"
                          ]
                        ]
                      ]
                    ]
                  ]
                ]
              ]
            ]
            7 => array:3 [
              "identificador" => "bib0280"
              "etiqueta" => "8"
              "referencia" => array:1 [
                0 => array:2 [
                  "contribucion" => array:1 [
                    0 => array:2 [
                      "titulo" => "Serious complications related to regional anesthesia&#58; results of a prospective survey in France"
                      "autores" => array:1 [
                        0 => array:2 [
                          "etal" => false
                          "autores" => array:6 [
                            0 => "Y&#46; Auroy"
                            1 => "P&#46; Narchi"
                            2 => "A&#46; Messiah"
                            3 => "L&#46; Litt"
                            4 => "B&#46; Rouvier"
                            5 => "K&#46; Samii"
                          ]
                        ]
                      ]
                    ]
                  ]
                  "host" => array:1 [
                    0 => array:1 [
                      "Revista" => array:6 [
                        "tituloSerie" => "Anesthesiology"
                        "fecha" => "1997"
                        "volumen" => "87"
                        "paginaInicial" => "479"
                        "paginaFinal" => "486"
                        "link" => array:1 [
                          0 => array:2 [
                            "url" => "https://www.ncbi.nlm.nih.gov/pubmed/9316950"
                            "web" => "Medline"
                          ]
                        ]
                      ]
                    ]
                  ]
                ]
              ]
            ]
            8 => array:3 [
              "identificador" => "bib0285"
              "etiqueta" => "9"
              "referencia" => array:1 [
                0 => array:2 [
                  "contribucion" => array:1 [
                    0 => array:2 [
                      "titulo" => "Guidelines for fellowship training in regional anesthesiology and acute pain medicine&#58; third edition&#44; 2014"
                      "autores" => array:1 [
                        0 => array:2 [
                          "etal" => true
                          "autores" => array:6 [
                            0 => "S&#46;L&#46; Kopp"
                            1 => "M&#46;J&#46; Hargett"
                            2 => "G&#46;A&#46; Liguori"
                            3 => "J&#46;M&#46; Neal"
                            4 => "L&#46; Le-Wendling"
                            5 => "E&#46;G&#46; Votta-Velis"
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                      "titulo" => "The philosophy of evidence-based medicine"
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                    0 => array:2 [
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                        "link" => array:1 [
                          0 => array:2 [
                            "url" => "https://www.ncbi.nlm.nih.gov/pubmed/20588150"
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                        "tituloSerie" => "Anesth Analg"
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                        "volumen" => "109"
                        "paginaInicial" => "993"
                        "paginaFinal" => "994"
                        "link" => array:1 [
                          0 => array:2 [
                            "url" => "https://www.ncbi.nlm.nih.gov/pubmed/19690282"
                            "web" => "Medline"
                          ]
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                ]
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              "identificador" => "bib0310"
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                0 => array:2 [
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                    0 => array:2 [
                      "titulo" => "Limitations and technical considerations of ultrasound-guided peripheral nerve blocks&#58; edema and subcutaneous air"
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                            4 => "G&#46; Kostopanagiotou"
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                        "paginaInicial" => "353"
                        "paginaFinal" => "356"
                        "link" => array:1 [
                          0 => array:2 [
                            "url" => "https://www.ncbi.nlm.nih.gov/pubmed/18675747"
                            "web" => "Medline"
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                      "doi" => "10.1007/s11695-013-0958-3"
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                        "tituloSerie" => "Obes Surg"
                        "fecha" => "2013"
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                        "paginaInicial" => "1309"
                        "paginaFinal" => "1314"
                        "link" => array:1 [
                          0 => array:2 [
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                0 => array:2 [
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                    0 => array:2 [
                      "titulo" => "Regional anaesthesia with US in obese patient"
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                0 => array:2 [
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                    0 => array:2 [
                      "titulo" => "Essential knobology for ultrasound-guided regional anesthesia and interventional pain management"
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                    ]
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              "referencia" => array:1 [
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                    0 => array:2 [
                      "titulo" => "A pocket guide to ultrasound-guided regional anaesthesia &#8211; UK"
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                  "host" => array:1 [
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                    0 => array:2 [
                      "titulo" => "Intraneural or extraneural&#58; diagnostic accuracy of ultrasound assessment for localizing low-volume injection"
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                          "etal" => false
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                        "tituloSerie" => "Reg Anesth Pain Med"
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                        "paginaInicial" => "409"
                        "paginaFinal" => "413"
                        "link" => array:1 [
                          0 => array:2 [
                            "url" => "https://www.ncbi.nlm.nih.gov/pubmed/25068413"
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                0 => array:2 [
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                    0 => array:2 [
                      "titulo" => "The use of the nerve stimulator with standard unsheathed needles in nerve blockade"
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                            3 => "M&#46;T&#46; Jenkins"
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                        "tituloSerie" => "Anesth Analg"
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                        "paginaInicial" => "827"
                        "paginaFinal" => "831"
                        "link" => array:1 [
                          0 => array:2 [
                            "url" => "https://www.ncbi.nlm.nih.gov/pubmed/4738206"
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              "identificador" => "bib0345"
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                0 => array:2 [
                  "contribucion" => array:1 [
                    0 => array:2 [
                      "titulo" => "Use of the nerve stimulator for peripheral blocks"
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                    ]
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                  "host" => array:1 [
                    0 => array:1 [
                      "Revista" => array:5 [
                        "tituloSerie" => "Reg Anaesth"
                        "fecha" => "1980"
                        "volumen" => "5"
                        "paginaInicial" => "7"
                        "link" => array:1 [
                          0 => array:2 [
                            "url" => "https://www.ncbi.nlm.nih.gov/pubmed/7071395"
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                0 => array:2 [
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                    0 => array:2 [
                      "titulo" => "Peripheral nerve stimulation in regional anesthesia"
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                          0 => array:2 [
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                      "titulo" => "High or low current threshold for nerve stimulation for regional anaesthesia"
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                    0 => array:2 [
                      "titulo" => "Inability to consistently elicit a motor response following sensory paresthesia during interscalene block administration"
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                        "paginaFinal" => "554"
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                        "tituloSerie" => "Acta Anaesthesiol Scand"
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                        "link" => array:1 [
                          0 => array:2 [
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                0 => array:2 [
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                    0 => array:2 [
                      "titulo" => "An ultrasonographic and histological study of intraneural injection and electrical stimulation in pigs"
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                          0 => array:2 [
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                    0 => array:2 [
                      "titulo" => "Intraneural injection with low-current stimulation during popliteal sciatic nerve block"
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                            4 => "J&#46; Gadsden"
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                        "link" => array:1 [
                          0 => array:2 [
                            "url" => "https://www.ncbi.nlm.nih.gov/pubmed/19608846"
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                      "titulo" => "Intraneural injection during nerve stimulator-guided sciatic nerve block at the popliteal fossa"
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                          0 => array:2 [
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                      "titulo" => "Minimal current intensity to elicit an evoked motor response cannot discern between needle-nerve contact and intraneural needle insertion"
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                        "paginaFinal" => "686"
                        "link" => array:1 [
                          0 => array:2 [
                            "url" => "https://www.ncbi.nlm.nih.gov/pubmed/24284806"
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                      "titulo" => "Signs of inflammation after sciatic nerve block in pigs"
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                        "paginaFinal" => "1846"
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                          0 => array:2 [
                            "url" => "https://www.ncbi.nlm.nih.gov/pubmed/16301271"
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                      "titulo" => "Intensity of the stimulating current may not be a reliable indicator of intraneural needle placement"
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                        "tituloSerie" => "Reg Anesth Pain Med"
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                        "paginaInicial" => "207"
                        "paginaFinal" => "210"
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                          0 => array:2 [
                            "url" => "https://www.ncbi.nlm.nih.gov/pubmed/18433670"
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                      "titulo" => "Extraneural versus intraneural stimulation thresholds during ultrasound-guided supraclavicular block"
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                      "titulo" => "Pathophysiology and etiology of nerve injury following peripheral nerve blockade"
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                        "tituloSerie" => "Reg Anesth Pain Med"
                        "fecha" => "2015"
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                          0 => array:2 [
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                        "link" => array:1 [
                          0 => array:2 [
                            "url" => "https://www.ncbi.nlm.nih.gov/pubmed/17961845"
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                    0 => array:2 [
                      "titulo" => "Longitudinal spread of intraneurally injected local anaesthetic"
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                        "tituloSerie" => "Acta Anaesthesiol Scand"
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                        "paginaInicial" => "622"
                        "paginaFinal" => "634"
                        "link" => array:1 [
                          0 => array:2 [
                            "url" => "https://www.ncbi.nlm.nih.gov/pubmed/726868"
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                    0 => array:2 [
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                        "link" => array:1 [
                          0 => array:2 [
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                0 => array:2 [
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                    0 => array:2 [
                      "titulo" => "Nerve expansion seen on ultrasound predicts histologic but not functional nerve injury after intraneural injection in pigs"
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                          0 => array:2 [
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                    0 => array:2 [
                      "titulo" => "Ultrasonographic appearance of intraneural injections in the porcine model"
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                          0 => array:2 [
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                        "tituloSerie" => "Anesth Pain Med"
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                          0 => array:2 [
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                    0 => array:2 [
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                        "paginaFinal" => "688"
                        "link" => array:1 [
                          0 => array:2 [
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                      "titulo" => "Injection pressure by anesthesiologists during simulated peripheral nerve block"
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                    0 => array:1 [
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                        "paginaFinal" => "205"
                        "link" => array:1 [
                          0 => array:2 [
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                0 => array:2 [
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                      "titulo" => "An animal model of syringe feel during peripheral block"
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                  "host" => array:1 [
                    0 => array:1 [
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                        "paginaFinal" => "332"
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                          0 => array:2 [
                            "url" => "https://www.ncbi.nlm.nih.gov/pubmed/19585700"
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                ]
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              "identificador" => "bib0470"
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                0 => array:2 [
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                    0 => array:2 [
                      "titulo" => "A simple low-cost way of measuring injection pressure during peripheral nerve block"
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                    0 => array:2 [
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                        "tituloSerie" => "Anaesthesia"
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                        "paginaInicial" => "956"
                        "link" => array:1 [
                          0 => array:2 [
                            "url" => "https://www.ncbi.nlm.nih.gov/pubmed/21916878"
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