Upper Extremity Peripheral Nerve Blocks

Upper Extremity Peripheral Nerve Blocks

การทำ peripheral nerve block ของ upper extremity ใช้เพื่อ

• surgical anesthesia
• postoperative analgesia
  สำหรับการผ่าตัดแขน มือ ไหล่ และ forearm หลายชนิด

---

Anatomy ที่สำคัญ

Brachial plexus

เกิดจาก ventral rami ของ C5–T1
แบ่งเป็น:

• Roots
• Trunks
• Divisions
• Cords
• Terminal branches

Major terminal nerves

Musculocutaneous nerve

• motor: biceps, brachialis
• sensory: lateral forearm

Axillary nerve

• sensory: shoulder capsule, skin over deltoid
• motor: deltoid, teres minor

Radial nerve

• motor: extensor arm/forearm
• sensory: dorsum hand/forearm

Median nerve

• motor/sensory: forearm flexors + hand

Ulnar nerve

• motor/sensory: intrinsic hand + medial forearm/hand

Important non-brachial plexus nerve

Intercostobrachial nerve (T2)

• sensory: axilla + medial upper arm
• ต้อง block เพิ่มหากใช้ upper arm tourniquet

---

Brachial Plexus Blocks

1. Interscalene block

Indications

ดีที่สุดสำหรับ:

• shoulder surgery
• proximal humerus surgery

Coverage

• block mainly C5–C7
• อาจ block C8–T1 ไม่ครบ → ไม่เหมาะกับ ulnar side hand surgery

Important point

• มักเกิด phrenic nerve block → hemidiaphragmatic paresis
• ระวังใน COPD / severe pulmonary disease

---

2. Suprascapular nerve block (SSN block)

Uses

• shoulder analgesia
• alternative when interscalene contraindicated
• chronic shoulder pain

Often combined with

• axillary nerve block
  เพื่อ phrenic-sparing analgesia

Technique

Anterior approach

• probe แบบ supraclavicular view
• inject 5–10 mL LA

Posterior approach

• identify suprascapular notch
• inject 5–8 mL LA beneath supraspinatus fascia

Complications

• pneumothorax
• vascular injury
• nerve injury
• unintended radial nerve block if LA spread proximally

---

3. Axillary nerve block

Uses

มักทำร่วมกับ SSN block สำหรับ shoulder analgesia

Technique

• posterior humerus approach
• inject 5–7 mL LA รอบ circumflex artery/axillary nerve bundle

Complication

• intravascular injection

---

4. Supraclavicular block

Level

block ที่ trunks level

Advantages

• rapid onset
• dense anesthesia
• ครอบคลุม distal upper extremity ดีมาก
• เหมาะกับ hand surgery และ tourniquet surgery

Risks

• pneumothorax
• vascular puncture
• phrenic nerve involvement น้อยกว่า interscalene

---

5. Infraclavicular block

Level

cords level

Advantages

• ดีสำหรับ distal arm surgery
• reliably blocks:
• axillary nerve
• musculocutaneous nerve
• เหมาะกับ continuous catheter มากกว่า supraclavicular

---

6. Axillary block

Level

terminal nerves level:

• median
• radial
• ulnar
• musculocutaneous

Important point

• musculocutaneous nerve อาจต้อง inject แยก
• intercostobrachial nerve ไม่ถูก block → ต้อง block เพิ่มถ้ามี tourniquet

Advantages

• safest brachial plexus block
• low pneumothorax risk

---

Intercostobrachial Nerve Block

Indications

• medial upper arm surgery
• upper arm tourniquet analgesia

Technique

• subcutaneous infiltration ที่ medial upper arm
• ใช้ LA 5–10 mL

---

Wrist Blocks

ใช้ supplement incomplete plexus block หรือทำ hand/finger surgery เล็ก ๆ

General principles

• ใช้ LA เพียง 3–5 mL ต่อ nerve
• หลีกเลี่ยง epinephrine → risk hand ischemia

---

Radial nerve block

ตำแหน่ง:

• proximal to radial styloid
• inject subcutaneous field block

---

Median nerve block

ตำแหน่ง:

• ระหว่าง palmaris longus กับ flexor carpi radialis tendon

---

Ulnar nerve block

ตำแหน่ง:

• medial to ulnar artery
• ใต้ flexor carpi ulnaris tendon

---

Drug Choices

Surgical anesthesia only

• 2% lidocaine
• 1.5% mepivacaine

Postoperative analgesia

• 0.25% bupivacaine
• 0.5% ropivacaine

Surgical anesthesia + prolonged analgesia

Rapid onset needed

mix:

• short-acting LA + long-acting LA

If onset delay acceptable

• 0.5% bupivacaine
• 0.5% ropivacaine

---

Continuous Peripheral Nerve Catheter

Infusion regimens

Inpatient

• 0.1% bupivacaine
• หรือ 0.2% ropivacaine
• 5–10 mL/hr

Ambulatory

• 0.2% ropivacaine
• 5–10 mL/hr

---

Intravenous Regional Anesthesia (Bier Block)

Uses

short procedures (<45 min):

• carpal tunnel release
• distal fracture reduction
• Dupuytren release

---

Technique summary

1.       IV catheter distal limb

2.       Exsanguinate arm (Esmarch)

3.       Inflate tourniquet

4.       Inject:

o   50 mL 0.5% lidocaine

o   forearm tourniquetใช้ ~30 mL

Important

• ห้ามใช้ bupivacaine → cardiotoxicity risk
• tourniquet ควร inflated ≥20 min ก่อนปล่อย

---

Complications of Upper Extremity Blocks

Common complications

• vascular puncture
• hematoma
• nerve injury
• infection
• local anesthetic systemic toxicity (LAST)

---

LAST (Local Anesthetic Systemic Toxicity)

Mild symptoms

• tinnitus
• circumoral numbness
• metallic taste
• dizziness

Severe symptoms

• seizure
• arrhythmia
• cardiac arrest

---

Block Selection (High-yield)

Surgery	Preferred block
Shoulder	Interscalene
Shoulder (pulmonary disease)	SSN + axillary
Elbow/forearm	Supraclavicular / infraclavicular
Hand surgery	Supraclavicular / axillary
Finger surgery	Wrist/digital block
Short distal procedure	Bier block

---

Pearls

• Interscalene → excellent shoulder block แต่ almost always affects phrenic nerve
• Supraclavicular → “spinal of arm” เพราะ dense reliable block
• Infraclavicular → best catheter stability
• Axillary → safest pneumothorax-wise
• อย่าลืม intercostobrachial nerve เมื่อใช้ upper arm tourniquet
• Avoid epinephrine in wrist/finger block
• Bier block: never use bupivacaine

Peripheral Nerve Blocks (PNB)

Peripheral Nerve Blocks (PNB)

Peripheral nerve block (PNB) คือการฉีด local anesthetic (LA) รอบ peripheral nerve หรือ plexus เพื่อให้เกิด surgical anesthesia หรือ analgesia โดยลด opioid requirement และหลีกเลี่ยงผลเสียของ GA/neuraxial anesthesia ได้ในหลายสถานการณ์

---

1. ข้อบ่งชี้ของ PNB

ใช้แทน General Anesthesia (GA)

เหมาะในผู้ป่วย:

• OSA
• severe obesity
• pulmonary disease
• difficult airway
• high PONV risk
• ต้องการหลีกเลี่ยง GA
• pregnancy

---

ใช้แทน Neuraxial anesthesia

เหมาะใน:

• anticoagulation/coagulopathy (เฉพาะ superficial/compressible block)
• severe aortic stenosis
• high urinary retention risk
• BPH
• elderly
• diabetes

---

Analgesia indications

เหมาะใน:

• opioid intolerance
• chronic opioid use
• ambulatory surgery
• severe acute pain
• respiratory compromise risk

---

2. Contraindications

Absolute contraindications

• patient refusal
• inability to cooperate
• LA allergy

---

Relative contraindications

• infection at injection site
• anticoagulation/coagulopathy
• preexisting neurologic deficit

---

3. Anticoagulation & Bleeding Risk

Risk สูงใน deep noncompressible blocks:

• lumbar plexus
• paravertebral
• quadratus lumborum
• proximal sciatic
• infraclavicular

หลักการ:

• superficial/compressible blocks → อาจทำได้
• deep blocks + anticoagulation → generally avoid

Complications:

• hematoma
• nerve compression
• occult blood loss

---

4. Types of Blocks

Single-shot block

• single injection
• duration:
• <1 hr → >24 hr
  ขึ้นกับ LA pharmacology

---

Continuous catheter block

• continuous infusion ผ่าน catheter
• prolonged analgesia
• ลด opioid use
• outpatient use ได้

---

5. Patient Preparation

ควรประเมิน:

• coagulation
• pulmonary disease
• neurologic deficits
• ability to ambulate after block

ผู้ป่วยควรทราบ:

• limb protection
• delayed complications
• fall precautions

---

6. Monitoring & Safety

ต้องมี:

• IV access
• ECG
• BP monitor
• pulse oximetry
• lipid emulsion 20%
• resuscitation equipment

---

7. Pre-procedure Checklist

Checklist สำคัญ:

• patient identity
• allergies
• coagulation status
• correct side
• surgical site marking
• block site marking

ช่วยลด wrong-sided block

---

8. Sedation

ควรให้ผู้ป่วย “awake but comfortable”

เป้าหมาย:

• ยังสื่อสารได้
• report paresthesia/injection pain ได้

Typical sedation:

• midazolam 1–2 mg IV
• fentanyl 25–100 mcg IV

---

9. Ultrasound Guidance

ปัจจุบันเป็น standard สำหรับหลาย blocks

ข้อดี:

• visualize nerve/vessel/needle
• increased success rate
• faster onset
• lower LA volume
• ลด vascular puncture
• ลด LAST
• ลด pneumothorax/phrenic nerve block

---

Ultrasound Techniques

In-plane

• เห็น entire needle
• safer
• preferred

Out-of-plane

• needle เห็นเป็น dot
• difficult tip visualization
• ใช้กับ deep blocks บางชนิด

---

10. Nerve Stimulator Guidance

หลักการ:

• electrical current → motor twitch
• current ต่ำลง = needle closer to nerve

Target:

• twitch at ≤0.5 mA
• disappear <0.4 mA

⚠️ diabetic neuropathy:

• stimulation threshold unreliable

⚠️ absence of twitch ≠ exclude intraneural placement

---

11. Continuous Catheter Technique

ข้อดี:

• prolonged analgesia
• ambulatory catheter possible

Outpatient catheter protocol ควรมี:

• written instructions
• 24h contact
• follow-up
• removal instructions

Catheter usually:

• sterile placement
• remove within 48–72 hr (infection risk starts rising)

---

12. Local Anesthetics (LA)

Short acting	Long acting
Lidocaine	Bupivacaine
Mepivacaine	Ropivacaine
	Levobupivacaine

หลักสำคัญ:

• higher concentration → faster onset
• long acting → prolonged analgesia
• mixing LA → unpredictable/intermediate effect

---

13. Adjuvants

Epinephrine

ช่วย:

• reduce systemic absorption
• prolong block
• detect intravascular injection

Typical:

• 1:200,000–1:400,000

---

Sodium bicarbonate

• faster onset
• evidence mixed

---

Dexamethasone

Most evidence-supported adjuvant

Benefits:

• prolong analgesia
• reduce PONV
• improve recovery

Dose:

• no clear benefit >4–5 mg

IV vs perineural:

• both effective
• perineural slightly longer in some studies
• perineural use = off-label

---

Alpha-2 agonists

Clonidine

ช่วย prolong block
แต่:

• hypotension
• bradycardia
• sedation

Dexmedetomidine

• improves block quality
• prolongs motor block
• bradycardia/hypotension risk

---

Opioids

• fentanyl/morphine in PNB → limited benefit

---

14. Rebound Pain

Definition:

• severe pain increase after block resolution

Incidence:

• up to ~80%

Prevention:

• educate patient
• start oral analgesics before block wears off
• avoid nighttime block resolution
• dexamethasone
• continuous catheter may help

---

15. Complications

Nerve Injury

Permanent injury:

• rare (~0.015–0.09%)

Transient symptoms:

• much more common

Mechanism:

• intrafascicular injection
• injection pressure
• neurotoxicity
• hematoma compression

Risk factors:

• diabetes
• preexisting neuropathy
• long-bevel needles

Warning signs:

• severe pain during injection
• paresthesia
• high injection pressure

Management:

• stop injection immediately

---

Hematoma

Riskสูงใน:

• anticoagulated patients
• deep blocks

---

LAST (Local Anesthetic Systemic Toxicity)

Presentation:

• tinnitus
• circumoral numbness
• seizure
• arrhythmia
• cardiac arrest

ต้องมี:

• lipid emulsion ready always

---

Infection

Single-shot:

• infection rare

Continuous catheter:

• colonization common
• clinical infection low (0–3.2%)

Risk factors:

• ICU
• trauma
• immunocompromised
• prolonged catheter duration

---

Myotoxicity

Rare:

• prolonged/high concentration LA
• symptoms may last months

---

Secondary Injury

Insensate limb injury

ต้อง:

• protect extremity
• educate patient

Falls

โดยเฉพาะ lower extremity blocks
→ assisted ambulation required

---

16. High-Yield Clinical Pearls

• Ultrasound guidance is current preferred standard
• Keep patient responsive during block placement
• Never inject against high resistance
• Severe injection pain = stop immediately
• Deep blocks + anticoagulation = high bleeding risk
• Always have lipid emulsion available
• Rebound pain prevention improves patient satisfaction
• Continuous catheter provides superior prolonged analgesia
• Motor block after lower extremity PNB increases fall risk

Epidural and Combined Spinal-Epidural (CSE) Anesthesia

Epidural และ Combined Spinal-Epidural (CSE) Anesthesia

Epidural anesthesia เป็น neuraxial anesthesia ที่ฉีด local anesthetic (LA) เข้า epidural space เพื่อ block spinal nerve roots ใช้สำหรับผ่าตัดช่องท้อง เชิงกราน lower extremities และ postoperative analgesia โดยมักใส่ catheter เพื่อให้ยาอย่างต่อเนื่อง ส่วน CSE เป็นการรวมข้อดีของ spinal (rapid dense block) กับ epidural (continuous/titratable anesthesia)

---

1. Epidural vs Spinal vs CSE

Technique	จุดเด่น	ข้อจำกัด
Spinal	onset เร็ว, dense block	duration จำกัด
Epidural	titrate ได้, continuous	onset ช้ากว่า
CSE	onset เร็ว + maintain ต่อเนื่อง	เทคนิคซับซ้อนขึ้น

• Epidural/CSE เหมาะเมื่อ:
• ต้องการ prolonged anesthesia
• ต้องการ postoperative analgesia
• ต้องการ titrate block level ได้

---

2. Relevant Anatomy

Epidural space boundaries

• Anterior: posterior longitudinal ligament
• Posterior: ligamentum flavum
• Lateral: pedicles/intervertebral foramina

Important ligaments

1.       Supraspinous ligament

2.       Interspinous ligament

3.       Ligamentum flavum → landmark สำคัญก่อนเข้า epidural space

Surface landmarks

• Iliac crest line ≈ L4
• Inferior scapula ≈ T7
• C7 spinous process = vertebra prominens

⚠️ landmark alone inaccurate → ultrasound increasingly useful โดยเฉพาะ obesity/anatomical difficulty

---

3. Preoperative Evaluation

ต้องประเมิน:

• coagulation/anticoagulant use
• spine abnormality
• neurologic disease
• infection
• hemodynamic reserve

Preprocedure checklist:

• patient identity
• consent
• coagulation status
• resuscitation drugs/equipment ready

---

4. Positioning

ใช้ได้ทั้ง:

• sitting
• lateral decubitus

เป้าหมาย:

• flex spine
• เปิด interspinous space
• ลด spinal rotation

Sitting position:

• insertion มักเร็วกว่า

---

5. Equipment สำคัญ

Epidural needle

• 17–18G
• Tuohy/Hustead/Weiss
• curved tip ช่วย guide catheter

Loss of resistance (LOR) syringe

ใช้ saline/air/both ได้

• ไม่มีหลักฐานชัดว่า saline หรือ air ดีกว่า

Epidural catheter

• flexible catheter → paresthesia/intravascular placement น้อยกว่า
• multiorifice catheter → analgesia อาจดีกว่า single-orifice

---

6. เทคนิค Epidural

Midline approach

Needle path:
skin → supraspinous → interspinous → ligamentum flavum → epidural space

Technique:

1.       local infiltration

2.       advance epidural needle

3.       attach LOR syringe

4.       advance slowly with pressure on plunger

5.       sudden LOR = epidural space

⚠️ stop advancing immediately after LOR → prevent dural puncture

---

Paramedian approach

เหมาะ:

• thoracic epidural
• calcified interspinous ligament
• inability to flex spine

Needle:

• 1 cm lateral
• contact lamina first
• redirect medially + cephalad

---

7. Epidural Catheter Placement

หลัง confirm epidural space:

• thread catheter
• leave catheter 4–6 cm in epidural space

⚠️

• <3 cm → dislodgement risk
• 7 cm → unilateral block/malposition risk

ตรวจ:

• aspiration ไม่มี blood/CSF
• secure dressing

---

8. Epidural Test Dose

เป้าหมาย:

• detect intravascular placement
• detect intrathecal placement

Standard test dose:

• 3 mL lidocaine 1.5% + epinephrine 1:200,000

Positive test:

• tachycardia within 1 min → intravascular
• dense motor block within 5 min → intrathecal

⚠️ beta-blocker อาจไม่มี tachycardia

---

9. Common Complications/Troubleshooting

Bone contact

• shallow = spinous process
• deep = lamina

แก้:

• withdraw slightly
• redirect cephalad/medial

---

False LOR

เกิดจาก:

• syringe leak
• exiting interspinous ligament into soft tissue

---

Difficult catheter threading

แก้:

• deep breath maneuver
• steeper needle angle
• inject saline

⚠️ ห้าม withdraw catheter ผ่าน needle → catheter shearing risk

---

Paresthesia

• stop advancing
• redirect away from symptomatic side

---

Blood aspiration

→ suspect intravascular placement

---

Unintentional dural puncture

Options:

1.       replace epidural elsewhere

2.       continuous spinal anesthesia (lumbar only)

⚠️ thoracic intrathecal catheter ไม่แนะนำ

---

10. Combined Spinal-Epidural (CSE)

ข้อดี:

• rapid dense spinal block
• maintain via epidural catheter

Technique:

1.       place epidural needle

2.       insert long spinal needle through epidural needle

3.       inject intrathecal drug

4.       remove spinal needle

5.       insert epidural catheter

---

11. Local Anesthetics

Drug	Onset	Duration	Notes
Lidocaine	5–15 min	90–120 min	rapid onset
Bupivacaine	15–25 min	2–4 hr	cardiotoxicity risk
Ropivacaine	15–20 min	1.5–3 hr	less motor block
Chloroprocaine	10–15 min	45–60 min	urgent cesarean

⚠️ 0.75% bupivacaine contraindicated in obstetric anesthesia

---

12. Epidural Adjuvants

Opioids

Fentanyl

• onset 5–15 min
• duration 1–2 hr

Morphine

• duration up to 24 hr
• delayed respiratory depression 6–18 hr ⚠️

Hydromorphone

• duration up to 18 hr

---

Epinephrine

ช่วย:

• prolong block
• reduce systemic absorption
• reduce LAST risk

Usual concentration:

• 1:200,000 (5 mcg/mL)

---

Clonidine

ช่วย prolong sensory block
แต่:

• hypotension
• bradycardia
• sedation

---

13. Hemodynamic Effects

คล้าย spinal แต่ onset ช้ากว่า

Hypotension

Management:

• IV crystalloid co-load
• phenylephrine
• ephedrine

Bradycardia

รักษา:

• atropine
• glycopyrrolate
• ephedrine

Severe:

• epinephrine + ACLS

---

14. Inadequate/Patchy Block

Management:

• increase LA volume
• repeat incremental dosing
• add opioid/epinephrine
• withdraw catheter 1 cm if unilateral block

ถ้ายัง failed:

• replace catheter
• spinal anesthesia
• convert GA

---

15. Maintenance

Methods:

• intermittent bolus
• continuous infusion

Typical infusion:

• bupivacaine 0.5%
• ropivacaine 0.75%
• ± fentanyl/hydromorphone

⚠️ inject incrementally always → reduce LAST/high spinal risk

---

16. Key Clinical Pearls

• LOR = most important procedural endpoint
• stop advancing immediately after LOR
• always aspirate before dosing
• all epidural doses should be incremental
• unilateral block often = catheter malposition
• high spinal risk increases after failed epidural followed by spinal
• neuraxial morphine requires delayed respiratory monitoring
• ultrasound increasingly valuable in obesity/difficult anatomy