a) Simple asphyxiants displace oxygen from the breathing atmosphere primarily in enclosed spaces and result in hypoxemia. Air hunger, fatigue, decreased vision, mood disturbances, numbness of extremities, headache, confusion, decreased coordination and judgment, cyanosis, and unconsciousness may be noted.

a) Fluorocarbons lower the myocardial threshold to the arrhythmogenic action of injected epinephrine in experimental animals.

a) Peak concentration and average level of fluorocarbon exposure reported in the breathing zone were 3200 cm(3)/m(3) and 170 cm(3)/m(3), respectively.
b) One subject in the exposed group had an arrhythmic tendency (frequent unifocal ventricular ectopic beats that often occurred as bigeminy or trigeminy) susceptible to different arrhythmogenic agents such as fluorocarbons and alcohol. Medical examination prior to inclusion attempted to rule out preexisting cardiovascular disease.

a) In dogs, inhalation of fluorinated hydrocarbon vapors causes bradycardia followed by junctional or ventricular escape rhythms, with deterioration to asystole or ventricular fibrillation in some animals (Flowers & Horan, 1972a; Flowers & Horan 1972b).
b) This occurs despite maintenance of normal oxygen and carbon dioxide tensions, pH, base excess, and serum carbon dioxide.
c) Epinephrine doses that produced minimal ECG alterations when administered alone, produced ventricular tachycardia and fibrillation when administered to dogs pretreated with the fluorocarbon compound, bromochlorodifluoromethane (Beck et al, 1973).

a) Four adults who received accidental injections of Freon 113(R) in the hand, knee, elbow, and forehead experienced temporary local redness which progressed over 30 to 40 minutes to more widespread blotchy redness, and then subsided. No other manifestations were noted (Personal Communication, 1988).
b) Goetting et al (1992) report 4 cases of accidental Freon injection with edema, crepitance, and transient pain. All injuries healed with no lasting sequelae following conservative treatment.
c) High pressure injection of a mixture of isopropanol and freon into a finger resulted in initial pain from the injection site to the axilla, which resolved over several hours. There was minimal tissue injury (Craig, 1984).

a) The patient presented 14 hours after exposure with compartment syndrome of the volar forearm and the adductor and interosseous compartments of the hand. Necrosis developed despite fasciotomy, requiring amputation of the fourth and fifth digits and ulnar half of the hand (Wegener et al, 1991).

a) The patient presented 14 hours after exposure with compartment syndrome of the volar forearm and the adductor and interosseous compartments of the hand. Necrosis developed despite fasciotomy, requiring amputation of the fourth and fifth digits and ulnar half of the hand (Wegener et al, 1991).

a) Monitor ECG.

a) PULSE OXIMETRY INDICATIONS - To obtain continuous, noninvasive measurement of arterial saturation in patients with respiratory complaints and those requiring assisted or mechanical ventilation (Galdun et al, 1989; Jones et al, 1988; Rose & Wolfson, 1989).
b) ACCURACY - Accurate for oxygen saturations between 65% and 100% and correlates well with ABGs (Jones et al, 1988; Yelderman & New, 1983). Factors affecting accuracy include (Galdun et al, 1989; Rose & Wolfson, 1989; Bowes et al, 1989; Phillips et al, 1989):
c) DISADVANTAGES - Relative insensitivity to changes in oxygenation occurring in upper portion of oxyhemoglobin dissociation curve; less sensitive than ABGs for detecting changes in pO2, especially in higher ranges of pO2 values (Rose & Wolfson, 1989).

a) Consider administration of activated charcoal after a potentially toxic ingestion (Chyka et al, 2005). Administer charcoal as an aqueous slurry; most effective when administered within one hour of ingestion.

a) Use a minimum of 240 milliliters of water per 30 grams charcoal (FDA, 1985). Optimum dose not established; usual dose is 25 to 100 grams in adults and adolescents; 25 to 50 grams in children aged 1 to 12 years (or 0.5 to 1 gram/kilogram body weight) ; and 0.5 to 1 gram/kilogram in infants up to 1 year old (Chyka et al, 2005).
b) ADVERSE EFFECTS/CONTRAINDICATIONS

a) To minimize barotrauma and other complications, use the lowest amount of PEEP possible while maintaining adequate oxygenation. Use of smaller tidal volumes (6 mL/kg) and lower plateau pressures (30 cm water or less) has been associated with decreased mortality and more rapid weaning from mechanical ventilation in patients with ARDS (Brower et al, 2000). More treatment information may be obtained from ARDS Clinical Network website, NIH NHLBI ARDS Clinical Network Mechanical Ventilation Protocol Summary, http://www.ardsnet.org/node/77791 (NHLBI ARDS Network, 2008)

a) Rewarming of a localized area should only be considered if the risk of refreezing is unlikely. Avoid rubbing the frozen area which may cause further damage to the area (Grieve et al, 2011; Hallam et al, 2010).

a) Do not institute rewarming unless complete rewarming can be assured; refreezing thawed tissue increases tissue damage. Place affected area in a water bath with a temperature of 40 to 42 degrees Celsius for 15 to 30 minutes until thawing is complete. The bath should be large enough to permit complete immersion of the injured part, avoiding contact with the sides of the bath. A whirlpool bath would be ideal. Some authors suggest a mild antibacterial (ie, chlorhexidine, hexachlorophene or povidone-iodine) be added to the bath water. Tissues should be thoroughly rewarmed and pliable; the skin will appear a red-purple color (Grieve et al, 2011; Hallam et al, 2010; Murphy et al, 2000).
b) Correct systemic hypothermia which can cause cold diuresis due to suppression of antidiuretic hormone; consider IV fluids (Grieve et al, 2011).
c) Rewarming may be associated with increasing acute pain, requiring narcotic analgesics.
d) For severe frostbite, clinical trials have shown that pentoxifylline, a phosphodiesterase inhibitor, can enhance tissue viability by increasing blood flow and reducing platelet activity (Hallam et al, 2010).

a) Digits should be separated by sterile absorbent cotton; no constrictive dressings should be used. Protective dressings should be changed twice per day.
b) Perform twice daily hydrotherapy for 30 to 45 minutes in warm water at 40 degrees Celsius. This helps debride devitalized tissue and maintain range of motion. Keep the area warm and dry between treatments (Hallam et al, 2010; Murphy et al, 2000).
c) The injured extremities should be elevated and should not be allowed to bear weight.
d) In patients at risk for infection of necrotic tissue, prophylactic antibiotics and tetanus toxoid have been recommended by some authors (Hallam et al, 2010; Murphy et al, 2000).
e) Non-tense clear blisters should be left intact due to the risk of infection; tense or hemorrhagic blisters may be carefully aspirated in a setting where aseptic technique is provided (Hallam et al, 2010).
f) Further surgical debridement should be delayed until mummification demarcation has occurred (60 to 90 days). Spontaneous amputation may occur.
g) Analgesics may be required during the rewarming phase; however, patients with severe pain should be evaluated for vasospasm.
h) IMAGING: Arteriography and noninvasive vascular techniques (e.g., plain radiography, laser Doppler studies, digital plethysmography, infrared thermography, isotope scanning), have been useful in evaluating the extent of vasospasm after thawing and assessing whether debridement is needed (Hallam et al, 2010). In cases of severe frostbite, Technetium 99 (triple phase scanning) and MRI angiography have been shown to be the most useful to assess injury and determine the extent or need for surgical debridement (Hallam et al, 2010).
i) TOPICAL THERAPY: Topical aloe vera may decrease tissue destruction and should be applied every 6 hours (Murphy et al, 2000).
j) IBUPROFEN THERAPY: Ibuprofen, a thromboxane inhibitor, may help limit inflammatory damage and reduce tissue loss (Grieve et al, 2011; Murphy et al, 2000). DOSE: 400 mg orally every 12 hours is recommended (Hallam et al, 2010).
k) THROMBOLYTIC THERAPY: Thrombolysis (intra-arterial or intravenous thrombolytic agents) may be beneficial in those patients at risk to lose a digit or a limb, if done within the first 24 hours of exposure. The use of tissue plasminogen activator (t-PA) to clear microvascular thromboses can restore arterial blood flow, but should be accompanied by close monitoring including angiography or technetium scanning to evaluate the injury and to evaluate the effects of t-PA administration. Potential risk of the procedure includes significant tissue edema that can lead to a rise in interstitial pressures resulting in compartment syndrome (Grieve et al, 2011).
l) CONTROVERSIAL: Adjunct pharmacological agents (ie, heparin, vasodilators, prostacyclins, prostaglandin synthetase inhibitors, dextran) are controversial and not routinely recommended. The role of hyperbaric oxygen therapy, sympathectomy remains unclear (Grieve et al, 2011).
m) CHRONIC PAIN: Vasomotor dysfunction can produce chronic pain. Amitriptyline has been used in some patients; some patients may need a referral for pain management. Inability to tolerate the cold (in the affected area) has been observed following a single episode of frostbite (Hallam et al, 2010).
n) MORBIDITIES: Frostbite can produce localized osteoporosis and possible bone loss following a severe case. These events may take a year or more to develop. Children may be at greater risk to develop more severe events (ie, early arthritis) (Hallam et al, 2010).

a) The peak blood level occurs immediately after inhalation of many fluorocarbons. Within 15 minutes, the blood fluorocarbon is almost completely gone. The significance of blood levels in relationship to catecholamine-induced arrhythmias is unknown.