New York City has its fair share of unusual calls, but one such recent call could have been disastrous for the patient.
Crews responded to an intoxicated male with the right side of his face swollen from an assault with a taxi cab mechanic at a West Side garage. The unlikely weapon -- a high pressure power washer used for degreasing livery cab engine compartments. Using the power tool to swat away the intoxicated assailant, the mechanic's helper sprayed the patient in the face from about a foot away at full blast, a hefty 1,000 psi at the tip, pushing him backward and causing soft tissue injuries.
The presentation was nothing out of the ordinary for a blunt force trauma assault. A pronounced area of swelling to the periorbital area was observed with no gross or unusual facial movement. A check of the eye showed extraocular movement to be intact. No evidence of hyphema or injection into the globe itself and no visual disturbances were reported. There was no evidence of subcutaneous emphysema to the face or orbit, but did that rule out air injection under the skin?
This would end up as a low priority transport to the local 9-1-1 receiving hospital. But this would turn out not to be in the patient's best interest.
High-Pressure Injection Injuries
Recently, a group from the University of Colorado described an estimated incidence of 1 in 600 hand injuries seen in their emergency department (ED). (1) These numbers suggest that high-pressure injection injuries (HPI) to the hand are relatively common, given the widespread use of pressure machinery in both industrial and domestic settings. According to an extensive study conducted by the Fluid Power Safety Institute, more than 99% of the people who service, repair and troubleshoot hydraulic systems have been subjected to the exact dynamics and forces that trigger an HPI. (2)
Some 60% of HPI are from paint, 25% from grease and 15% from any balance of hydraulic fluids. The typical presentation is in the young male in the industrial/service industry setting. Injures occur in the non-dominant hand in 75% of the cases.
HPI occur from devices that direct gasses and other substances under high pressures and even at high temperatures. They can be found in the home garage and industrial and construction sites. Devices and tools like grease guns, sandblasters, industrial paint sprayers, the high pressure hoses of the hydraulic rescue tools, hydraulic hoses on heavy construction machinery and aircraft can all exert pressures from several hundred pounds to several thousand pounds per square inch of pressure.
Some sources in the literature suggest forces less than 7,000 psi are of little prognostic value, yet at the same time, they suggest that values above 7,000 psi increase the likelihood of amputation, and they also note that a delay in care can mean an amputation rate increase of 50%. Also interesting to note in the literature is that any time definitive care is delayed, the rate of amputations increases.
Fluid and air under pressure can easily penetrate the skin and dissect deep tissues and compartments as they seek the path of least resistance. Generally, they'll track through the fascial planes and neurovascular bundles.Skin penetration has been recorded at distances of four inches from fluid source to skin. (3)
HPI to the hand have a unique prognostics profile associated with the point of entry -- injection into the digit and its tendon sheath can have a dramatically poor prognosis, whereas the palm's anatomy, which is not entirely governed by fascial planes, can have a better prognosis.
Not all injuries occur the in hands or in adults. There are reports in the literature of an adult patient suffering from a pneumocranium and a child sustaining from bicycle spoke puncture to the ankle with a pressurized air injection. (4,5)
Adding insult to injury, the substances being injected cause their own damage to tissues. Corrosives, solvents, paints, grease and hydraulic fluids all have corrosive or toxicological properties that can directly impact morbidity. Paints will generally have a necrotic effect on tissues, while grease will generally cause fibrosis. Water jets can inject skin flora and other bacteria in the tissue, creating serious infections, as well as septic arthritis. Cements are extremely problematic as they can have a pH as high as 13 and create a thermal injury because the curing process creates an exothermic reaction. Grease will create an oleoma in the acute phase of the injury and, if not treated, will result in a mass and fibrosis that can persist for years. (6)
Presentation & Treatment
Management is based on supporting the patient and maintaining a high index of suspicion. Compartment syndromes, vessel thrombosis, serious infections and tissue necrosis can develop rapidly after HPI. Initially, the patient may complain only of mild pain and may even continue working, leading to a delay in definitive care. The injured area may at first seem innocuous, presenting as a small pinprick. EMS providers and ED personnel who aren't familiar with this injury may regard it as insignificant, causing further delay in management, or worse, allow the patient to refuse care and leave. The injured area, particularly if it's a digit, can eventually become extremely painful before becoming insensate. The tissue compartment will become edematous, tense, pale and finally pulseless. Subcutaneous emphysema may or may not be present, so it's best not to make a diagnostic decision based on the presence or absence of this finding.
Care in the ED should include Doppler measurement of blood flow in the affected appendage, surgical exploration and debridement, as well wound culturing and antibiotic prophylaxis. (7) X-rays can be helpful in treating injuries with such products as dense lubricants and paints that are radiopaque. Air-filled cavities will also show up on x-ray.
Due to a high index of suspicion, our patient was transported to a Level 1 Trauma Center for evaluation by a trauma surgeon. He was subsequently treated and released with a follow-up scheduled at the maxillofacial clinic the next day to rule out the onset of periorbital cellulits.
Louis Cook, AS, EMT-P, is a 21-year veteran of EMS. He is a 9/11 survivor and is assigned to the FDNY Special Operations Command-Haz Tac Battalion. Lt. Cook is a certified rescue paramedic and Haz Mat Technician 2 and Diver Medical Technician. He is completing his BS degree in disaster and emergency management.
The author wishes to thank Rory McLaren of the Fluid Power Safety Institute (FPSI) for the gracious use of their photographs. FPSI will be releasing "Lethal Strike" an educational DVD from the FPSI in late summer 2008.
1. Schoo MJ, Scott FA, Boswick JA Jr.: "High-pressure injection injuries of the hand."Journal of Trauma. 20(3):229Ï238, 1980.
2. Fluid Safety Power Institute: "The Lethal Strike."www.fluidpowersafety.com
3. Scott AR: "Occupational high-pressure injection injuries: pathogenesis and prevention."The Journal of the Society of Occupational Medicine. 33(2):56Ï59, 1983.
4. Chu FY, Wu KC, Lin HJ: "Craniofacial high-pressure air injection injury."Annals of Emergency Medicine. 49(1):113Ï114, 2007.
5. Afshar A: "Pressurized air injection causing subcutaneous emphysema in a pediatric patient."The Journal of Foot and Ankle Surgery. 47(1):66Ï68, 2008.
6. Mason MK, Queen FB: "Grease gun injuries to the head: Pathology and treatment of injuries (oleomas) following the injection of grease under pressure."Quarterly Bulletin of Northwestern Medical School. 15:122, 1941.
7. Jungpal SA, William R, Turner RB, et al: "High-Pressure Injection Injuries."www.emedicine.com/orthoped/topic402.htm