Fire
Fire related injuries can cause:

1. Thermal burns
2. Chemical injury

Thermal burn usually occurs at the skin or airway, the latter being the more serious referred to as thermal mucosal burn or edematous inhalation injury. When the extremely hot air is inspired, an inflammatory reaction happens around the airway. This swelling or constriction of the airway makes it difficult or sometimes impossible to breath. Thus the victim may show signs of dyspnea, stridor and hypoxia. Other clues may be a cough, a changed voice, burnt face, stinged eyebrows and nose hairs, carbon deposits around the mouth, carbonaceous sputum.

Chemical injury referred to as gas inhalation injury is also very serious. The severity depends on what toxin is inspired (dependant on what is burning) and the concentration in the bloodstream. There are 35000 known toxins including CO, SO2, HCN, CO2, HS, etc. CO is the most common. It is a systemic toxin produced by the incomplete combustion of carbon containing substances. It is dangerous because it's affinity for hemoglobin (Hb) on red blood cells is 250 times greater than that of oxygen. If inspired, the oxygen saturation curve shifts to the left (Bohr effect) thus leading to hypoxic injury. The heart and brain are especially vulnerable. At 20% CO-Hb victims may present with headache, nausea, vomiting, dyspnea, dizziness. At 20-40% CO-Hb they show visual disturbances, irritability, poor judgment. At 40-60% CO-Hb they show confusion, seizure, coma, ataxia, syncope. At levels greater than 60% victims usually cannot survive because the cardiovascular and respiratory systems collapse and they go into shock.

What to do as a rescuer if faced with fire at the scene? Call 911 and wait for the firefighters to clear the danger. Do not attempt to do so by yourself.

Wire
Highly charged wires are extremely hot and can cause very dangerous fires (this should always be kept in mind). Coming in contact with a wire can lead to:

1. Thermal burns
2. Electrical deregulation in the body

There are 5 critical factors that determine the severity of the electrical injury:

• Tissue resistance (proportional to the dryness of the skin)
• Current intensity (how many amps? often only the voltage is known, so you can approximate from that)
• AC (120V/240V found in house outlets) vs. DC (12V found in batteries and cars)
• Duration of contact
• Current path

Current travels in the path of least resistance. In the body, the most resistant organ is the skin and the least are the vessels. Therefore the path of least resistance is usually: skin - bones - muscles - nerves - vessels. The current path can be determined by looking for an entrance wound (looks like a bullet wound) and an exit wound. This can be helpful because it gives the rescuer a good idea as to what organs might be affected. If the heart is affected the victim may show an arrhythmia, ventricular fibrillation or asystole. If the brain is affect then the respiratory centers in the medulla are deregulated leading to respiratory failure. If the muscles are affected then there may be tetanic contractions.

What to do as a rescuer? Wait for a Hydro Quebec worker or other qualified person to remove the wire.

Gas
Noxious levels of gas are very difficult to detect and sometimes overlooked. They can be the result of:

1. A gas leak
2. Combustion (look for signs of fire)

Scenes were gas may be a serious danger include cars in closed environments, trains derailed, volatile metals burning, tires burning, insecticides burning. Insecticides are especially alarming because they release organophosphates that lead to a cholinergic syndrome characterized by salivation, lacrimation, urination, defecation and gastric emesis (S.L.U.D.G.E.).

Gases are classified into the following categories:

• Asphyxiants: target the lungs
  CO, HCN, hydrocarbons (methane, propane, common in barbeques)
• Systemic toxins: prevent oxygen transport or use by cells
  CO, HCN, CS2
• Simple irritants: cause inflammation
  NH3/4 (also know as ammonia), Cl
• Combined irritant and systemic toxin: H2S (smells like rotten eggs, similar to HCN), metallic oxides

CO and HCN are two important gases. CO's effect was discussed in the section about fire. HCN has a distinct smell like bitter almonds and is usually found around pest control products, photography equipment or metal polishing. Affected people present with dryness, air hunger, dyspnea, confusion, seizure, cardiovascular collapse, shock. The mechanism of action being that the CN binds Fe3 (ferric state) thereby inhibiting cytochrome oxidase and ultimately inhibiting oxidative phosphorylation.

Glass
With glass, you can cut yourself and…

1. Lose blood
2. Get an infection

Try to carefully clear the glass around the victim with a towel or other object before approaching.

Blood
If there is blood on or around the victim, first think to put on gloves before approaching. The actual risk of disease transmission during mouth-to-mouth ventilations is small with only 15 cases reported in scientific journals in the past 40 years. Of the 15 cases, there were no cases of HIV, hepatitis B/C or cytomegalovirus - arguably the most life threatening diseases. Still, according to one survey, only 5% of people would be willing to perform mouth-to-mouth ventilations on a stranger indicating that there is a prevalent fear of disease transmission. If the rescuer feels uncomfortable about performing mouth to mouth, then there are options.

Compression only CPR is one such option which has been proven to be a very effective alternative (see the physiology section in the CPR step for details). Also, rescuers can and should use facemasks whenever possible to prevent direct contact and fluid exchange. If you think that you may have been exposed to suspect blood, you can always visit the emergency department (the faster the better) and they'll check you out and take the appropriate course of action.

how well do you know your stuff?