Overview of Peripheral Nerve Blocks



The symptoms of a PDPH sometimes are not a classic headache but are instead dizziness, auditory changes, visual disturbances, or neck pain that are positional in nature.


 

2) Symptoms (2)


    a) Characteristics


  i) Onset is usually 12 to 48 hours after dural puncture.


  ii) PDPH is located in the frontal or occipital region.


  iii) Accompanying symptoms include neck pain, visual disturbances (which may be due to cranial nerve palsies), photophobia, nausea and vomiting, dizziness, and auditory changes.


(1) Double vision is possible due to traction on the VI cranial nerve.


    b) Positional changes


  i) The classic symptom of PDPH is that the headache (HA) is relieved upon assuming the supine position and worsened in the upright position.


1) Incidence of HA with dural puncture depends on several variables


    a) Needle size


  i) In general, the larger the needle, the higher the incidence of HA.


    b) Needle type


  i) Pencil-point needles (Whitacre, Sprotte, and Gertie-Marx) have a lower incidence of HA than cutting-point needles (Quincke).


(1) For example, a 26-g Quincke needle has a PDPH incidence of 5%, while a 25-g Whittacre needle has an incidence of approximately 1% (3).


    c) Bevel direction


  i) If a Quincke needle is used, care should be taken to orient the bevel of the needle with the longitudinal axis of the spine as this decreases the incidence of headache.


    d) Patient characteristics


  i) Female patients and/or those younger than 40 years have a higher incidence of PDPH than male patients and those over 60 years old.


  ii) Morbidly obese patients have a lower incidence of PDPH.


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Always consider the differential diagnosis of headache. Never assume that a headache is PDPH until other causes are ruled out by a thorough chart review, history, and physical exam.


4) Patient evaluation


    a) The patient must have a thorough history and physical examination.


    b) The onset, characteristics, severity, and exacerbating factors should be determined.


    c) A thorough chart review should focus on coexisting disease, vital signs (especially temperature and blood pressure), and laboratory evaluations such as the white blood cell count.


    d) Physical exam should be focused on ruling out neurologic deficits.


5) Differential diagnosis


    a) Preeclampsia


  i) Hypertensive disorders of pregnancy are often accompanied by HA.


    b) Musculoskeletal HA


  i) Patients may have muscle tension headaches from lying in bed.


  ii) Postpartum patients may experience muscle tension due to breast-feeding.


    c) Caffeine withdrawal


  i) Patients who regularly consume caffeine may experience HA when caffeine is withheld.


    d) Pneumocephalus


  i) Immediate onset of severe HA can be associated with pneumocephalus due to use of the loss of resistance to air technique for localizing the epidural space and subsequent unintended dural puncture.


(1) High inspired O2 concentration can result in improvement of symptoms (2).


    e) Subarachnoid hematoma


  i) Sudden onset of severe HA and/or accompanying neurological deficits may be the result of a ruptured of cerebral aneurysm and/or arteriovenous malformation (2).


    f) Venous sinus thrombosis


  i) Peripartum patients are at higher risk for this condition, and many will have undergone dural puncture for labor analgesia or cesarean delivery.


  ii) In these patients, the HA loses its positional nature and/or other neurologic signs/symptoms are present over time (4).


    g) Subdural hematoma


  i) Decreased CSF volume from dural puncture rarely may result in bleeding from cerebral vessels.


    h) Migraine


  i) In patients with a history of migraine HA, it is important to differentiate between his/her typical symptoms and PDPH.


  i) Meningitis


  i) The presence of fever and nuchal rigidity is an ominous sign in a patient with HA.


(1) Antibiotic therapy must be started in a timely manner.


6) Conservative treatment


    a) IV and/or oral hydration


  i) While widely prescribed for treatment of PDPH, there is no evidence supporting the benefit of hydration for PDPH (2).


    b) Caffeine


  i) The effectiveness of caffeine has been debated, but studies have shown a modest benefit to oral and IV caffeine (5,6).


(1) Caffeine is a central nervous stimulant with side effects of insomnia, arrhythmias, and seizures and should not be used for long-term therapy.


    c) Supine position


  i) Maintaining the supine position after dural puncture is not effective in preventing or treating PDPH (2).


    d) Other treatments


  i) The most consistently effective and well-studied treatment for PDPH is an epidural blood patch (EBP).


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In postpartum patients with PDPH, patient safety is an important concern as they often are sleep deprived and have children to care for at home.


7) Natural course of PDPH


    a) In most patients, the HA resolves after 1 to 2 weeks.


    b) However, performance of daily activities is impaired in many patients and can last up to 1 month. Rarely, symptoms can last much longer (years in some patients) (2).


  i) The importance of this in parturients cannot be emphasized enough, as this patient population expects to care for an infant and often other children.


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Epidural anesthesia, Chapter 31, page 237


Lumbar epidural placement, Chapter 161, page 1118


 

8) Epidural blood patch


    a) Effectiveness


  i) The reported success rate of EBP varies significantly. In one study, the success rate of EPB in a heterogeneous population that included parturients was 75% (7).


  ii) The rate of success depends on the type of needle used for dural puncture, with large bore needles resulting in lower success rates.


  iii) When the EBP is delayed for 24 hours after the dural puncture, it is more effective (8).


    b) Informed consent


  i) The patient should be counseled about the possibility of repeat dural puncture and worsening HA.


  ii) The most common complaint after EBP is back pain lasting up to 1 week.


  iii) Otherwise, the risks are equivalent to the risks of epidural placement.


    c) Performing EBP


  i) Meticulous sterile technique must be maintained.


  ii) Many patients are not comfortable in the upright position, so the lateral position may be used.


(1) However, especially in patients with potentially difficult EBP, the upright position can be used, with care taken to minimize the time the patient spends in this position.


  iii) The epidural space is localized.


  iv) Blood is obtained under sterile conditions by an assistant and passed to the person performing the epidural.


  v) After aspiration for blood and CSF, the blood should be injected in 5-ml increments to a total of 20 mL or until the patient experiences pressure in his/her head or back.


  vi) The patient should then lie flat for approximately one hour, after which he or she is reassessed for resolution of HA (9).


  vii) In the days following the procedure, the patient should be advised against heavy lifting and valsalva maneuvers, which may dislodge the clot.


  viii) Patient follow-up is extremely important in order to monitor for complications and ensure resolution of the HA.


    d) EBP through an epidural catheter


  i) The effectiveness of EBP performed through an epidural catheter in parturients with unintended dural puncture was recently examined. In this study, the duration of the HA was shortened, but the incidence and severity were unchanged (10).


  ii) Given this information, this author recommends EBP through an epidural catheter only for patients whose epidural catheters were extremely difficult to place and are at high risk for repeat dural puncture with EBP.


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Patient follow-up after PDPH diagnosis is essential.


 

Contraindications to EBP


    a) Immunosuppression, systemic infection, coagulation disorder, and patient refusal


10) 10) Other treatments


    a) Intrathecal catheter


  i) Recent evidence in parturients suggests that when an unintended dural puncture occurs and the anesthetic plan included an epidural catheter, placing the catheter in the intrathecal space may reduce the incidence of PDPH.


  ii) HA incidence is reduced most in patients whose catheter is left in place for 24 hours after delivery (11).


  iii) Extreme caution must be taken when an intrathecal catheter is in place.


(1) Communication to all staff (nursing, obstetrics, and anesthesia) about the presence of an intrathecal catheter is paramount.


(2) Clearly label the catheter as intrathecal in order to prevent administration of medications intended for intravascular or epidural administration.


(3) Care must also be taken to prevent infection.


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Patients with a perioperative or postpartum HA require a thorough evaluation to eliminate causes other than CSF leak from dural puncture.


 

11) Managing a patient with a PDPH in whom EBP has been ineffective


    a) In the vast majority of patients with PDPH, two blood patches will result in resolution symptoms.


    b) Indications for imaging studies and/or consultation with a neurologist include unresolved headache after two EBP, worsening HA severity, changing characteristics (including loss of positional nature), fever, and associated sensory or motor deficits.



Chapter Summary for PDPH and Epidural Blood Patch


 

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References


1. Gaiser R. Postdural puncture headache. Curr Opin Anaesthesiol 2006;19:249–253.


2. Weeks SK. Postpartum headache. In: Chestnut DH, ed. Obstetric Anesthesia: Principles and Practice. 3rd ed. Philadelphia, PA: Elsevier Mosby; 2004:562–578.


3. Lambert DH, Hurley RJ, Hertwig L, et al. Role of needle gauge and tip configuration in the production of lumbar puncture headache. Reg Anesth 1997;22(1):66–72.


4. Lockhart E, Baysinger C. Intracranial venous thrombosis in the parturient. Anesthesiology 2007;2007(4):652–658.


5. Halker RB, Demaerschalk BM, Wellik KE, et al. Caffeine for the prevention and treatment of postdural puncture headache: debunking the myth. Neurologist 2007;13(5):323–327.


6. Camann WR, Murray RS, Mushlin PS, et al. Effects of oral caffeine on postdural puncture headache. A double-blind, placebo-controlled trial. Anesth Analg 1990;70(2):181–184.


7. Safa-Tisseront V, Thormann F, Malassine P, et al. Effectiveness of epidural blood patch in the management of post-dural puncture headache. Anesthesiology 2001;95(2):334–339.


8. Vilming S, Kloster R, Sandvik L. When should an epidural blood patch be performed in postlumbar puncture headache? A theoretical approach based on a cohort of 79 patients. Cephalgia 2005;25:523–527.


9. Martin R, Jourdain S, Clairoux M, et al. Duration of decubitus position after epidural blood patch. Can J Anaesth 1994;41(1):23–25.


10. Scavone BM, Wong CA, Sullivan JT, et al. Efficacy of a prophylactic epidural blood patch in preventing post dural puncture headache in parturients after inadvertent dural puncture. Anesthesiology 2004;101(6):1422–1427.


11. Ayad S, Demian Y, Narouze S, et al. Subarachnoid catheter placement after wet tap for analgesia in labor: Influence on the risk of headache in obstetric patients. Reg Anesth Pain Med 2003;28:512–515.



33

Combined Spinal-Epidural Technique


 

Andrea J. Fuller, MD


 


The combined spinal-epidural (CSE) technique involves administering a dose of medication in the intrathecal space and also placing an epidural catheter. It is widely used for labor analgesia and may be utilized for nonobstetric procedures.


1) Indications


    a) Labor analgesia


  i) Rapid onset of analgesia


  ii) Improved patient satisfaction in some studies (1)


  iii) Lower incidence of motor block, especially if intrathecal opioids are given without local anesthetic (e.g., “walking epidural” [1])


    b) Operative procedure of uncertain duration


  i) A CSE can be placed in patients who strongly desire a regional anesthetic but whose procedure length may exceed the duration of the local anesthetic chosen for a single injection spinal (1).


    c) Administration of long-acting epidural medication


  i) The CSE technique may be used when one prefers the rapid onset of a spinal anesthetic but would like to have an epidural in place for administration of long-acting epidural medications, such as sustained-release epidural morphine (DepoDur) (2).


2) Technique


    a) Needle-through-needle (Fig. 33-1)



Figure 33-1 Needle-Through-Needle Technique for CSE


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1. Epidural space is located with standard techniques; 2. Spinal needle is inserted through epidural needle and may cause tenting of the dura prior to puncture; 3. Dura is punctured and free flow of CSF confirmed. Intrathecal injection is now administered; 4. Epidural catheter is placed; 5. Epidural needle is removed and catheter is secured. Modified from Eisenach JC. Combined spinal-epidural analgesia in obstetrics. Anesthesiology 1999;91(1):299–302.


  i) Most common CSE technique


  ii) The epidural space is localized with the loss of resistance to saline or air technique.


  iii) A spinal needle is placed through the epidural needle.


  iv) A characteristic “pop” is felt and free flow of cerebrospinal fluid (CSF) observed.


  v) Spinal medication is administered and the spinal needle removed.


  vi) The epidural catheter is then placed and secured.


    b) Separate procedures


  i) When the epidural and spinal are performed separately, they can be done at the same or different interspinous spaces.


  ii) It is advisable to place the spinal portion first as it is theoretically possible to traumatize a previously placed epidural catheter when the spinal needle passes through the epidural space.


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When saline is used for the epidural portion of CSE, it is important to confirm free flow of CSF to avoid the possibility of mistaking saline for CSF, resulting in failed spinal block.


 

1) Failures with the CSE technique (Fig. 33-2)



Figure 33-2 Possibilities for CSE Block Failure


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1. Length of spinal needle protruding through the epidural needle is too short to puncture dura; 2. Tip of spinal needle “tents” the dura but fails to pierce it; 3. Malposition of the epidural needle away from midline causing the spinal needle to miss the dural sac; 4. Correct position of epidural and spinal needles.Adapted from Hughes SC. Intraspinal analgesia in obstetrics, Part II: Clinical applications. In: Hughes SC, Levinson G, Rosen MA, eds. Shnider and Levinson’s anesthesia for obstetrics. 4th ed. Philadelphia, PA: Lippincott Williams & Wilkins, 2002:161.


    a) Failure of spinal portion of block


  i) “Tenting” of the dura—low dural pressure (3)


(1) More likely when the procedure is done in the lateral position due to lower CSF pressure


  ii) Off midline


(1) When the needle is not in the midline, it is possible for the spinal needle to be lateral to the dural sac (3).


  iii) Spinal needle not long enough to puncture dura (3,4)


  iv) Mistaken saline for CSF when LOR to saline technique is used


(1) Must confirm free flow of CSF in spinal needle before injection


    b) Failure of epidural


  i) Untested catheter


(1) It is advisable to avoid CSE in patients with a difficult airway if one must rely on the epidural catheter for surgery (e.g., cesarean section)


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For patients for whom the reliability of an epidural catheter is extremely important (severe preeclampsia, difficult airway, nonreassuring fetal heart rate tracing), it may be advisable to avoid the CSE technique in favor of epidural placement.


4) Complications


    a) Fetal bradycardia


  i) Association of fetal bradycardia with CSE labor analgesia is controversial and likely related to rapid onset of analgesia resulting in excess maternal circulating catecholamines affecting uterine tone (5).


  ii) Hypotension


  iii) Respiratory depression


(1) Estimated incidence of 0.01% to 0.1% with intrathecal fentanyl and/or sufentanil


(2) Higher incidence with higher doses


    b) Rates of other complications associated with neuraxial analgesia are similar (6,7).


  i) Postdural puncture headache


  ii) Intravascular catheter


  iii) Intrathecal catheter


(1) Concerns regarding epidural catheter migration through the dural hole have not been substantiated when studied (8).


  iv) Infection


(1) The incidence of infection is so low that the relative risk of meningitis for CSE versus epidural is unclear, but it appears to be similar with CSE as with other neuraxial techniques (7).


  v) Bleeding


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ALL epidural catheters should be aspirated for blood or CSF prior to dosing at any time.



Chapter Summary for CSE


 

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References


1. Collis RE, Davies DW, Aveling W. Randomised comparison of combined spinal-epidural and standard epidural analgesia in labour. Lancet 1995;345:1413–1416.


2. Carvalho B, Riley ET, Cohen SE, et al. Single-dose, sustained-release epidural morphine in the management of postoperative pain after elective cesarean delivery: Results of a multicenter randomized controlled study. Anesth Analg 2005;100(4):1150–1158.


3. Hughes SC. Intraspinal analgesia in obstetrics, part II: clinical applications. In: Hughes SC, Levinson G, Rosen MA, eds. Shnider & Levinson’s Anesthesia for Obstetrics. 4th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2002:155–188.


4. Riley ET, Hamilton CL, Ratner EF, et al. A comparison of the 24-gauge sprotte and gertie marx spinal needles for combined spinal-epidural analgesia during labor. Anesthesiology 2002;97(3):574–577.


5. Eisenach JC. Combined spinal-epidural analgesia in obstetrics. Anesthesiology 1999;91(1):299–302.


6. Norris MC, Fogel ST, Conway-Long C. Combined spinal-epidural versus epidural labor analgesia. Anesthesiology 2001;95(4):913–920.


7. Rawal N, Holmstrom B, Crowhurst JA, et al. The combined spinal-epidural technique. Anesth Clin North America 2000;18(2):267–295.


8. Holmstrom B, Rawal N, Axelsson K, et al. Risk of catheter migration during combined spinal epidural block: percutaneous epiduroscopy study. Anesth Analg 1995;80(4):747–753.



34

Overview of Peripheral Nerve Blocks


 

Russell Kinder, MD • Robert L. Hsiung, MD


 


A peripheral nerve block (PNB) involves the injection of local anesthetic medication in the vicinity of a target nerve to inhibit neural transmission, producing surgical anesthesia in the distribution of the peripheral nerve and/or postoperative analgesia in the same distribution. Excluded from the definition are neuraxial blocks and intravenous regional anesthesia techniques. Specific nerve block techniques are described in detail in their respective chapters.


1) Basics of peripheral nerve blocks


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Atlas of Peripheral Nerve Block Procedures Section 13 page 1171


 

    a) Basic peripheral nerve anatomy


  i) The upper extremity is innervated by the branches of the brachial plexus, formed from the anterior rami of the C5-T1 nerve roots (Figs. 34-1 and 34-2).


(1) Proximal blocks of the brachial plexus include the interscalene and supraclavicular approaches.


(2) Distal blocks of the brachial plexus include the infraclavicular and axillary approaches.



Figure 34-1 Illustration of the Brachial Plexus from Roots to Branches


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From Chelly JE, ed. Peripheral Nerve Blocks: A Color Atlas. 2nd ed. Philadelphia, PA, Lippincott Williams & Wilkins; 2009: 20



Figure 34-2 Innervation of the Upper Extremity by Individual Peripheral Nerve


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From Chelly JE, ed. Peripheral Nerve Blocks: A Color Atlas. 2nd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2009: 32.


  ii) The lower extremity is innervated by branches of the lumbar plexus (L1-4) (Figs. 34-3 and 34-4) and sacral plexus (L5-S3) (Fig. 34-5).


(1) The lumbar plexus and branches may be blocked posteriorly or anteriorly.


(2) The major branch of the sacral plexus, the sciatic nerve, may be blocked in a number of locations along its course.



Figure 34-3 Branches of the Lumbar Plexus Important in Lower Extremity Innervation


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From Chelly JE, ed. Peripheral Nerve Blocks: A Color Atlas. 2nd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2009: 76.



Figure 34-4 Branches of the Sacral Plexus Important in Lower Extremity Innervations


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From Chelly JE, ed. Peripheral Nerve Blocks: A Color Atlas. 2nd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2009: 79.



Figure 34-5 Innervation of the Lower Extremity by Individual Peripheral Nerve


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From Chelly JE, ed. Peripheral Nerve Blocks: A Color Atlas. 2nd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2009: 74.


    b) Local anesthetics and adjuncts used for peripheral nerve blockade (Table 34-1)



Table 34-1
Table of Common Local Anesthetics (LA) Used for Peripheral Nerve Blocks


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aConcentration and volumes used depend on desired effect (e.g., anesthesia vs. analgesia), location of the block, and nerve localization technique used. The lower concentrations are typically used for continuous infusions.
bOnset time and block duration depend on dose of LA, block location, and the use of adjuncts.
cActual plasma concentration can vary greatly, with toxicity being possible at much lower doses.


  i) Many local anesthetics can be used for peripheral nerve blocks with differing concentrations and volumes in order to achieve the anticipated density, onset, and duration of the block.


  ii) Individual characteristics are discussed in the local anesthetic chapter.


  iii) Vasoconstrictors such as epinephrine prolong block duration and delay systemic absorption of local anesthetics as well as help identify intravascular injection, but its addition may increase the risk of neuronal injury (1).


  iv) Sodium bicarbonate has been used to hasten block onset for intermediate-acting local anesthetics (2).


  v) Clonidine added to local anesthetics can prolong block duration for single-injection blocks only (2,3).


    c) Contraindications


  i) Absolute contraindications (4)


(1) Active skin infection over the site of planned needle placement


(2) Severe coagulopathy


(3) Allergy to local anesthetic medication


(4) Patient refusal


(5) Coagulopathy


   (a) The American Society of Regional Anesthesia has not released specific guidelines on peripheral nerve blocks in anticoagulated patients (5).


   (b) Certain peripheral nerve blocks in noncompressible areas (e.g., paravertebral and lumbar plexus blocks) should be considered high risk for bleeding complications and are best avoided in the anticoagulated patient.


  ii) Adverse outcomes have been reported from peripheral nerve blocks performed under general anesthesia, and this practice in adults remains controversial (6).


2) Benefits of peripheral nerve blocks


    a) Peripheral nerve blocks can be used by themselves as an anesthetic technique or in conjunction with general anesthesia.


  i) As a primary anesthetic technique, peripheral nerve blockade may bypass many of the potential dangers of general anesthesia such as difficult airways, nausea and vomiting, hemodynamic instability, and malignant hyperthermia.


  ii) Studies suggest that the use of peripheral nerve blocks, especially continuous peripheral nerve catheters, provides better analgesia compared to opioids, greater patient satisfaction, decreased pruritus, decreased nausea vomiting, improved sleep, and decreased length of hospitalization (4).


  iii) To date, however, no mortality studies have demonstrated a conclusive advantage in favor of peripheral nerve block (PNB) anesthesia, nor has there been convincing evidence that suggests perioperative peripheral nerve blocks improve quality of life and rehabilitation (7).


    b) Placement of a peripheral nerve catheter can allow for continuous perineural infusion or repeated boluses of local anesthetic, providing a longer duration of analgesia than can be obtained with a single-shot nerve block


1) Risks of peripheral nerve blocks


    a) Specific risks associated with axillary, infraclavicular, interscalene, distal elbow and wrist, supraclavicular, popliteal, femoral, sciatic, and ankle blocks are discussed in their respective chapters


    b) These risks may include infection, neurologic injury, local anesthetic toxicity, pneumothorax, and ipsilateral diaphragmatic paralysis.


    c) General techniques to decrease the risks of peripheral nerve blocks (discussed individually), include performing a good history and physical, performing these blocks only when indicated, checking coagulation status or assessment for bacteremia when indicated, using sterile technique, performing incremental injection and aspiration, and using a “test dose” of epinephrine-containing local anesthetic to avoid intraneural or intravascular injection.


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Continuous peripheral nerve blocks, Chapter 35, page 256


Overview of Peripheral Nerve blocks, Chapter 34, page 256


 

  i) Preventing infection


(1) The risk of infection from a peripheral nerve block (PNB) is low but may be increased with the use of indwelling catheters.


(2) Infection rate is decreased by the use of sterile technique, and the risks and benefits of performing the block should be reassessed in the setting of bacteremia or overlying skin infection.


  ii) Minimizing neurological injury


(1) A meta-analysis of 32 studies over a 10-year period found 3% rate of any neurological event after peripheral nerve blocks (interscalene > axillary > femoral nerve blocks) and only one case of permanent neuropathy (8).


(2) There have been no randomized clinical studies that clearly demonstrate nerve stimulation or ultrasound-guided peripheral nerve block (PNB) to have lower complication rates compared to transarterial or paresthesia techniques.


(3) However, many practitioners believe that direct visualization under ultrasound may minimize needle-to-nerve trauma, as motor response may not be elicited even if the needle is intraneural (9).


(4) Other possible factors that may lead to increased neurologic injury are the injection of local anesthetics after paresthesia elicitation and injection of local anesthetics under high pressure or resistance (10,11).


  iii) Detecting systemic toxicity


(1) Toxicity from local anesthetics primarily affects the central nervous system (CNS) and the cardiovascular system.


   (a) CNS toxicity symptoms progress from oral numbness, dizziness, and visual disturbances to seizures and coma.


   (b) If allowed to evolve unimpeded, local anesthetic systemic toxicity may progress to cardiovascular toxicity, manifesting as an arrhythmia or a complete cardiovascular collapse.


(2) Most cases of systemic toxicity have been attributed to inadvertent intravascular injection of local anesthetic.


(3) The maximum doses of specific local anesthetics with and without epinephrine are discussed separately


  iv) Minimizing the risk of bleeding


(1) Unlike the risk of anticoagulation in neuraxial blocks, the risk of vascular injury for peripheral nerve blocks in anticoagulated patients is not well defined (5).


(2) While placement of nerve blocks in severely coagulopathic patients should be avoided, peripheral nerve blocks are generally considered relatively safe compared to neuraxial blocks.


(3) Hematomas may be more common with the use of continuous catheters than with single-injection techniques due to the larger gauge catheter-introducing needle (2).


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Local anesthetics, Chapter 37, page 282

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