Elsevier

Burns

Volume 25, Issue 1, February 1999, Pages 49-52
Burns

On burn injuries related to airbag deployment

https://doi.org/10.1016/S0305-4179(98)00110-7Get rights and content

Abstract

Airbags have been shown as a vital, supplemental restraining device that save lives and reduce morbidity associated with motor vehicles crashes. However, as with any developing technology, airbags have also been identified in some instances, as the source of injuries which, have been well described in the literature. To a significantly lesser degree, burns due to airbag deployment (about 7–8% of these injuries) have been reported. These injuries will be seen more frequently as more vehicles are equipped with airbags and should be suspected in drivers and passengers involved in accidents in which airbags have been activated. This article, reviews the various types of burns and their pathogenesis, found in crashes involving airbag deployments.

Introduction

The effectiveness of the airbag as a safety device in decreasing fatalities and reducing morbidity is well established. Airbags reduce the fatal injuries by 45–55% if the driver is belted (lap-shoulder seatbelt) and by 20–40% if the driver is unbelted1, 2, 3.

In 1949, the first patent for the automobile airbag was applied for and was issued in 1953. Early systems were associated with many technical problems and did not gain acceptance until improvements were made. It was not until 1970 that the problems with release and detonation could be rectified[4]. Since 1980, vehicles in the USA have been increasingly equipped with the airbag. The Federal Motor Vehicles Safety Standard No. 208, “Occupants Crash Protection” requires that all passenger cars manufactured after September 1, 1989 be equipped with automatic crash protection.

Congress has required that dual airbags be installed in all new passenger cars by September 1, 1997 and in all vans, pickup trucks and utility vehicles by September 1, 1998[5]. It is estimated by the National Highway Traffic Safety Administration (NHTSA) that by the year 2000 more than 500,000 airbag deployments will occur each year in the USA[6]. Cumulative data from systemic studies indicate that airbag associated injuries occur frequently. About 30% of drivers sustained some sort of airbag injury to the head, erythema, minor skin abrasions to the face chin or neck as well as injuries and abrasions to the upper chest, hands, wrists and forearm7, 8. The general conclusion is that restraint systems are working to reduce many of the head chest and abdominal injuries suffered by unrestrained occupants[9]. However these injuries still occur among airbag protected occupants. Serious and fatal injuries were also reported, including: blow-out fracture of the orbit, blunt injuries of the abdomen, rupture of the right atrium and aortic transection and fatal craniocervical injuries10, 11, 12, 13, 14, 15, 16.

The airbag is a round inflatable, rubber-lined woven nylon bag with a diameter slightly larger than the size of the steering wheel and approximately 10 inches deep at its central point when fully inflated[6]. The airbag crush sensors, located within the forward portion of the vehicle or in the passenger compartment, detect the rapid deceleration associated with a frontal impact and are designed to inflate the airbag in response to sudden longitudinal deceleration similar to that which occurs when a vehicle travelling at 13–26 km/h collides with a barrier[17]. Approximately 70 g of sodium azide is ignited releasing nitrogen (96%), carbon dioxide (3%) and miscellaneous gases and particulates (1%), as well as a small amount of alkaline aerosol containing sodium hydroxide, sodium carbonate and metallic oxides, causing a 60-l airbag to inflate in about 0.01 of a second, propelling it out of the storage compartment at a speed greater than 160 kph (157–338 km/h). Passenger-vehicle airbags are de ployed by the rapid generation of a large volume of gas. This forms a transient cushion between the driver and the steering wheel, or between the passenger and the dashboard and the windshield. Within 2 s deflation then occurs as the hot gases are released into the passenger compartment under intense pressure 150–170 dB wave through two exhaust ports, or a porous panel, located on the back of the airbag module. (Table 1)4, 6, 17, 18.

A review of the pertinent literature4, 18, 19shows that airbag-induced injuries can be grouped in four general types according to the percentage of patients who sustained the different types of injuries: abrasions (68.6%), contusions (37.8%), lacerations (18.2%), burns (7.8%), fractures (3.2%) and retinal detachment (1.8%). Hallock[18]divided the airbag related burns into 3 main categories:

  • 1.

    thermal

      (a)

      direct burn from high-temperature gases

      (b)

      indirect burn due to melting of clothing

  • 2.

    chemical

      (a)

      alkaline corrosives, especially sodium hydroxide

      (b)

      particulate materials; effect yet unknown

  • 3.

    friction

Section snippets

Thermal burns

The combustion process releases a significant amount of heat. The heat of the gas released has melted lightweight polyester blouses and gloves causing minor burns to the respective parts of the body6, 20. Duma[19]described an exceptional case of thermal burns to the ocular region and face from the airbag. In this case the design failed (the exhaust vents were located at the nine and three o’clock positions on the rear of the airbag) and the inflation process burned two holes through the front

Chemical burns

By-products of combustion create a fine alkali aerosol containing sodium hydroxyide, sodium carbonate and other metallic oxides. This aerosol is considered to be highly corrosive (Table 2)[21]and has been implicated in the alkaline chemical keratitis, facial erythema and contact dermal burns. For this to occur the aerosol has to go into solution (sweat, tears, etc.)[22].

Of all burns related to airbags a special emphasis should be put on alkali keratitis because if not treated properly and

Friction burns

Friction burns caused by airbags are commonly found on the face, chin and neck (Fig. 1)[29]. It has been shown that these injuries are primarily the result of high velocity fabric impact, the inflation is forceful and the face is often the point of maximum airbag impact, which explains the tendency of increasing prevalence of airbag-related injuries of these areas. It has been calculated[30]that the pressure sufficient to breach the normal intact skin is about 7 atm (100 psi). It is believed

Conclusions

Burns attributed to the airbag are mostly light and superficial except for the alkali burns to the eye which can result in permanent visual impairment and are therefore potentially devastating. Immediate diagnosis and treatment (urgent ophthalmologic consultation is advised) are essential to a good prognosis.

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