Fascial plane blocks: TAP, ESP, and QL

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Why this is examined / the one-line answer

Fascial plane blocks dominate modern acute pain and ERAS vivas because they are common, high-volume, LAST-relevant, and often oversold as “epidural replacements.” Examiners want indications, coverage limits, volumes, LAST readiness, and a Plan B when the wall is numb but the patient still hurts.[3][4]

One-liner: I match TAP/QL/ESP to the surgical incision, inject dilute local anaesthetic under ultrasound within maximum dose, warn that visceral pain remains, and combine with systemic multimodal analgesia. [1]

Anatomy that changes the plan

TAP (transversus abdominis plane)

LA deposited between internal oblique and transversus abdominis. Targets thoracolumbar nerves supplying the abdominal wall. Landmark/US subcostal, lateral, and posterior approaches change cranial coverage. Classic evidence supports reduced opioid use after abdominal surgery when appropriately applied.[4]

Good for: lower abdominal wall (Pfannenstiel, open appendicectomy, some midline lower).
Limits: poor visceral cover; upper abdominal may need subcostal TAP or other techniques. [1]

QL (quadratus lumborum)

LA around quadratus lumborum (lateral/posterior/anterior approaches — exam: know that approach variants exist and may spread differently). Potential for wider coverage including some lateral cutaneous and possibly more paravertebral-like spread depending on approach — also deeper, with denser anticoagulation concern than superficial TAP. [1]

ESP (erector spinae plane)

LA deep to erector spinae muscle, superficial to transverse processes — described for thoracic neuropathic pain and widely used for rib fractures, thoracic and abdominal surgery as part of multimodal care.[1][3]

Mechanism viva: proposed craniocaudal fascial spread and possible paravertebral/epidural seepage — exact mechanism debated; clinical effect is real but variable. [1]

Indications matrix

Volumes, concentration, LAST maths

• Fascial planes are volume-dependent (often 15–30 mL per side of dilute long-acting LA such as ropivacaine 0.2–0.375% or equivalent, within maximum dose).
• Bilateral doubles the dose — recalculate mg/kg before drawing up.
• Count surgeon’s infiltration in the same daily maximum.
• Lower concentration, adequate volume is the plane-block philosophy; toxicity is still dose × absorption. [1]

LAST: large fascial volumes are a classic modern LAST setting. Know early CNS signs, cardiovascular collapse, and ASRA lipid emulsion pathway (20% lipid, airway, benzodiazepines for seizures, modified ACLS).[2]

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Anaesthetic goals

1. Match plane to incision.
2. Ultrasound visualisation of plane and spread.
3. Stay within maximum LA dose.
4. Realistic expectations (somatic > visceral).
5. Multimodal systemic cover.
6. Document drug, volume, laterality, time. [1]

Technique decision points

• In-plane US preferred for tip control.
• Hydrodissection confirms plane — watch for intraperitoneal or intramuscular pattern.
• Anticoagulation: apply ASRA-style timing — deeper QL/ESP catheters are not “risk free” because they are not neuraxial.
• Catheters: continuous infusions need LAST maths per hour and secure fixation. [1]

Monitoring and equipment

Ultrasound with appropriate probe; block needle; calibrated LA syringes; full monitoring; lipid emulsion accessible; resuscitation equipment; consent including failure and LAST. [1]

Intraoperative / PACU management

Assess block with cold/pinprick in expected dermatomes. If wall numb but pain severe → visceral pain, referred pain, or failed segment — add systemic multimodal/ketamine/PCA, do not only “top up” past toxic dose. Mobilise within ERAS if motor sparing (usually is). [1]

Crisis pivots

LAST suspected

Stop injection, call for help, ABC, 100% oxygen, benzodiazepine for seizures, lipid emulsion per ASRA checklist, prolonged CPR if arrest.[2]

Incomplete analgesia

Rescue multimodal; consider second technique only within dose limits; exclude surgical complication. [1]

Peritoneal / intravascular injection concern

Stop, reassess, observe for LAST, do not chase remaining volume if landmarks lost. [1]

Hypotension after large volume

Usually not epidural-like sympathectomy (variable with ESP/QL); consider absorption/sedation, bleeding, or anaphylaxis differentials. [1]

Postoperative / ERAS role

Plane blocks reduce opioid need and support mobilisation when combined with paracetamol/NSAID/early feeding pathways. They do not replace good surgical technique, PONV prophylaxis, or fluid discipline. Audit block success and LAST near-misses. [1]

Special populations

• Pregnancy: TAP for caesarean adjunct — dose carefully, aortocaval awareness when positioning.
• Obesity: deeper images, longer needles, dose on lean/IBW caution for LA mg/kg.
• Coagulopathy: prefer superficial techniques or avoid deep planes.
• Paediatrics: weight-based volumes strictly. [1]

SAQ answer scaffold

Outline the role of bilateral TAP blocks after open hysterectomy. [1]

1. Anatomy/indication (3): abdominal wall somatic cover; limited visceral.[4]
2. Technique (3): US plane, volume/concentration, max dose.
3. LAST (3): calculate dose, lipid ready.[2]
4. Multimodal (2): systemic analgesics for visceral pain.
5. Failure plan (2): PCA/APS, not endless LA.

Viva stem bank and model phrases

Stem 1: “TAP vs epidural for open colectomy?”
Model: “TAP helps wall pain and opioid sparing but does not match epidural visceral and thoracic coverage; I individualise within ERAS multimodal care.” [1]

Stem 2: “What is ESP?”
Model: “Local anaesthetic deep to erector spinae over transverse processes — used for thoracic and trunk analgesia with ultrasound; mechanism of spread is debated.”[1]

Stem 3: “Bilateral 25 mL of 0.375% ropivacaine — concern?”
Model: “Large total dose — I calculate mg/kg including any infiltration and keep lipid available.” [1]

Stem 4: “Patient still writhing with numb skin.”
Model: “Visceral pain or incomplete cover — treat systemically; plane blocks are not complete anaesthesia of the abdomen.” [1]

Stem 5: “QL on therapeutic anticoagulation?”
Model: “Deeper plane — I apply ASRA-style risk stratification; often avoid or delay.” [1]

Stem 6: “Why dilute large volumes?”
Model: “Planes need volume for spread; concentration trades density against mass dose and toxicity.” [1]

Stem 7: “Chest wall blocks literature?”
Model: “Fascial plane chest wall techniques are established adjuncts; I match block to incision and respect dose.”[3]

Common traps

• Overselling as epidural replacement
• Bilateral max-dose ignorance
• No lipid in room
• Expecting visceral silence
• Deep plane on full anticoagulation
• Not counting surgical infiltrate
• Injecting without seeing spread [1]

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Ultrasound landmarks — exam sequences

Lateral TAP: probe mid-axillary between costal margin and iliac crest; identify external oblique, internal oblique, transversus abdominis; needle in-plane to IO–TA plane; hydrodissect lens-shaped spread. [1]

Subcostal TAP: probe parallel to costal margin for upper abdominal wall coverage. [1]

QL: identify QL adjacent to transverse process/psoas/erector; approach-specific targets (lateral/posterior/anterior) — state your local preferred approach and risks (deeper, organ proximity). [1]

ESP: probe parasagittal paramedian; identify transverse processes and erector spinae; needle onto TP plane; craniocaudal hydrodissection.[1]

Worked dose example

80 kg patient, bilateral lateral TAP for lower midline: ropivacaine 0.25% 20 mL each side = 100 mg total (1.25 mg/kg) — within common max ranges if no other LA. If surgeon adds 20 mL 0.5% bupivacaine infiltration, you may exceed safe mass — coordinate before drawing up.[2]

Catheters and continuous infusions

Continuous TAP/ESP catheters can extend opioid-sparing into day 2–3 for laparotomy or rib fractures. Problems: dislodgement, leak, patchy coverage, cumulative LAST from infusion plus boluses, and infection. Label pumps clearly; use dilute concentrations; set hourly limits; review daily with APS. [1]

Examiner mental map

1. Match block to surgery.
2. Anatomy of each plane.
3. Volume/dose/LAST.
4. Coverage limits (visceral).
5. Anticoagulation depth risk.
6. Failure rescue within multimodal ERAS. [1]

Realistic plane-block talk scores higher than miracle claims. [1]

References

1. [1]Forero M, Adhikary SD, Lopez H, Tsui C, Chin KJ. The Erector Spinae Plane Block: A Novel Analgesic Technique in Thoracic Neuropathic Pain Reg Anesth Pain Med, 2016.PMID 27501016
2. [2]Neal JM, Barrington MJ, Fettiplace MR, et al. The Third American Society of Regional Anesthesia and Pain Medicine Practice Advisory on Local Anesthetic Systemic Toxicity: Executive Summary 2017 Reg Anesth Pain Med, 2018.PMID 29356773
3. [3]Chin KJ, Versyck B, Pawa A. American Society of Regional Anesthesia and Pain Medicine Local Anesthetic Systemic Toxicity checklist: 2020 version Reg Anesth Pain Med, 2021.PMID 33148630
4. [4]McDonnell JG, O'Donnell B, Curley G, et al. Ultrasound guidance in regional anaesthesia Br J Anaesth, 2005.PMID 15277302