Tumescent anaesthesia

Principles

• Tumescent = swollen; subcutaneous tissues distended with large-volume dilute LA solution.
• Pharmacokinetics: slow systemic absorption due to adrenaline-induced vasoconstriction → peak serum lidocaine ~12-14 hours post-infiltration; well below toxic threshold despite high total dose.
• Klein 1987: established safety of 35 mg/kg in liposuction; subsequent series support up to 55 mg/kg in selected patients.
• Benefits: extensive anaesthesia, near-bloodless field, hydrodissection of planes, ambulatory procedures, avoidance of general anaesthesia.

Standard Klein formula

Per 1000 mL bag of 0.9% normal saline (or Ringer's lactate):

• Lidocaine 1% — 50 mL (= 500 mg) → final 0.05% (500 mg / 1000 mL)
• Adrenaline 1:1000 — 1 mL (= 1 mg) → final 1:1 000 000
• Sodium bicarbonate 8.4% — 10 mL → final ~10 mmol/L (buffers pH; reduces injection pain)
• ± Triamcinolone 10 mg (some formulations)

Modified concentrations:

• 0.1% lidocaine for face / hands.
• 0.025-0.05% for trunk / limb / liposuction.
• 0.05-0.1% for axillary / inguinal lymphadenectomy.

Technique

1. Infiltrate using a long blunt-tipped tumescent cannula (3-4 mm) or 18-22G spinal needle.
2. Inject through multiple small skin entry points; multidirectional pattern; targeting subcutaneous plane.
3. Infiltrate until tissue is firm and pale (peau d'orange appearance).
4. Wait 10-20 minutes for full vasoconstriction effect (maximal vasoconstriction at 30 minutes).
5. Volumes vary: 500-3000 mL for liposuction; 200-500 mL for large WLE; 100-300 mL for lipoma; 500-1500 mL per limb for vein surgery.
6. For liposuction the wet ratio (mL infused : mL aspirated) defines:
   • Dry — 1:<1 (historical, high blood loss)
   • Wet — 1:1
   • Super-wet — 1:1 to 1:1.5
   • Tumescent — 1:2 to 1:3

Safety considerations

• Maximum total lidocaine: classically 35 mg/kg; up to 55 mg/kg in healthy patients with appropriate monitoring; reduce in elderly, hepatic / renal impairment, drug interactions.
• Drug interactions: lidocaine metabolised by CYP3A4 and CYP1A2; reduce dose if patient on amiodarone, clarithromycin, fluoxetine, fluconazole, itraconazole, beta-blockers.
• Peak serum lidocaine at 12-14 h — late LAST possible; counsel patient about delayed-onset toxicity warning signs; arrange next-day check.
• Fluid considerations: large volumes can cause pulmonary oedema in cardiac / renal compromise — particularly with high-volume liposuction.
• Hypothermia: room-temperature fluid in large volumes lowers core temperature; warming devices, blankets.
• Toxicity: same management as standard LAST (Intralipid available).
• Monitor pulse, BP, SpO2 throughout; have full resuscitation including Intralipid on site.

Practical points

• Document: total volume, total lidocaine in mg, total mg/kg, time of completion of infiltration.
• Schedule procedures to allow full vasoconstriction time before incision (20-30 min).
• Combine with regional / general anaesthesia for major liposuction / lymphadenectomy.
• Avoid intravascular injection — aspirate; use blunt cannula technique.
• Post-operative drainage of residual tumescent fluid common; counsel about pink drainage for 24-48 h.
• Ambulatory phlebectomy and many dermatologic procedures done under tumescent alone with conscious sedation.