See [Dunn - pressure gun injuries and tendon sheath infections](x-devonthink-item://04193935-249C-4D07-B6C2-4D8DADE35CC3) eg from airless spray guns (pressure 21,000 kN/m2), may be going 180m/sec, or grease guns (700kN/m2) - form of [[Weapons of Mass destruction#Blast injuries|blast injury]] - injects *noxious material* into pulm and flexor tendon sheaths causing *progressive necrosis* - due to pressure, injected fluid can travel a significant distance from the site of entry - chemical injury - soluble hydrolics are often alkali - hydrocarbon solvents (eg [[Toluene toxicity|toluene]]) are far more damaging than paint or grease injection - low MW hydrocarbons (eg white spirit, kerosene) may induce local anaesthesia due to dissolution of fat and myelin nerve sheaths - higher viscosity agents (eg hydrolic mineral oils) have less penetration but may be more difficult to remove - *tissue is under marked tension* → secondary ischaemia may occur **Assessment** - ==hand may initially look completely normal== with only small entry wound - XR - gas in the tissues - highly sensitive for lead based pain - 50% sensitive for grease - distal fingertip injuries a/w higher tissue tension and greater risk of necrosis - fuel and paint injuries a/w greatest inflammatory response → **70% amputation rate!** - low viscosity agents cause more toxicity because more tissue spread **management** - ==refer to hand surgeon ASAP== → higher risk of amputation if >10 hours before operative intervention - systemic analgesia → ==DO NOT== do local anaesthetic blocks as it may further increase tissue tension - local anaesthetics potentiate the myelinolytic effects of low viscosity hydrocarbons - splint and elevate hand - ADT booster - abx (cefazolin) - Surgical treatment involves: - open exoloration - remove foreign material - loose wound closure - post op steroids