Sedentary Work Exerting up to 10 pounds (4.5 kg) of force occasionally and/or a negligible amount of force frequently or constantly to lift, carry, push, pull, or otherwise move objects, including the human body. Sedentary work involves sitting most of the time, but may involve walking or standing for brief periods of time. Jobs are sedentary if walking and standing are required only occasionally and other sedentary criteria are met.

Light Work Exerting up to 20 pounds (9.1 kg) of force occasionally and/or up to 10 pounds (4.5 kg) of force frequently, and/or negligible amount of force constantly to move objects. Physical demand requirements are in excess of those for Sedentary Work. Light Work usually requires walking or standing to a significant degree. However, if the use of the arm and/or leg controls requires exertion of forces greater than that for Sedentary Work and the worker sits most the time, the job is rated Light Work.

Medium Work Exerting up to 50 (22.7 kg) pounds of force occasionally, and/or up to 25 pounds (11.3 kg) of force frequently, and/or up to 10 pounds (4.5 kg) of forces constantly to move objects.

Heavy Work Exerting up to 100 pounds (45.4 kg) of force occasionally, and/or up to 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Very Heavy Work Exerting in excess of 100 pounds (45.4 kg) of force occasionally, and/or in excess of 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Job Classification

In most duration tables, five job classifications are displayed. These job classifications are based on the amount of physical effort required to perform the work. The classifications correspond to the Strength Factor classifications described in the United States Department of Labor's Dictionary of Occupational Titles. The following definitions are quoted directly from that publication.

Sedentary Work Exerting up to 10 pounds (4.5 kg) of force occasionally and/or a negligible amount of force frequently or constantly to lift, carry, push, pull, or otherwise move objects, including the human body. Sedentary work involves sitting most of the time, but may involve walking or standing for brief periods of time. Jobs are sedentary if walking and standing are required only occasionally and other sedentary criteria are met.

Light Work Exerting up to 20 pounds (9.1 kg) of force occasionally and/or up to 10 pounds (4.5 kg) of force frequently, and/or negligible amount of force constantly to move objects. Physical demand requirements are in excess of those for Sedentary Work. Light Work usually requires walking or standing to a significant degree. However, if the use of the arm and/or leg controls requires exertion of forces greater than that for Sedentary Work and the worker sits most the time, the job is rated Light Work.

Medium Work Exerting up to 50 (22.7 kg) pounds of force occasionally, and/or up to 25 pounds (11.3 kg) of force frequently, and/or up to 10 pounds (4.5 kg) of forces constantly to move objects.

Heavy Work Exerting up to 100 pounds (45.4 kg) of force occasionally, and/or up to 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Very Heavy Work Exerting in excess of 100 pounds (45.4 kg) of force occasionally, and/or in excess of 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Inhalation Burns


Related Terms

  • Inhalation Injury
  • Smoke Inhalation

Differential Diagnosis

Specialists

  • Critical Care Internist
  • Emergency Medicine Physician
  • General Surgeon
  • Internal Medicine Physician
  • Medical Toxicologist
  • Pharmacologist
  • Plastic Surgeon
  • Preventive Medicine Specialist
  • Psychiatrist

Comorbid Conditions

Factors Influencing Duration

The duration of illness depends on the extent of the injury and the health status of the individual prior to the inhalation burn. Damage to the individual's respiratory system may prolong recovery. A combination of skin and inhalation burns increases morbidity and death rates.

Medical Codes

ICD-9-CM:
947.0 - Burn of Mouth and Pharynx; Gum; Tongue
947.1 - Burn of Larynx, Trachea, and Lung
947.2 - Burn of Esophagus

Overview

Inhalation burns can be caused by smoke, hydrofluoric acid, ammonia, chlorine, or other chemical agents after an individual inhales these toxic substances. Cyanide (CN) toxicity can come from exposure to the toxic debris of burning polyurethane, wool, or silk items. Upper airway edema, respiratory distress, and carbon monoxide (CO) toxicity are the hallmarks of injury from inhalation. These symptoms appear within 12 to 24 hours following the occurrence of the burn. Also, a rare condition may occur in which chemical toxicity or the heat from fire oxidizes lung hemoglobin, resulting in impaired oxygen transport (methemoglobinemia) and respiratory distress. Inhalation injury is more likely to occur in fires in enclosed areas.

There are usually three phases for significant inhalation injuries. The first phase is marked by upper airway swelling and blockage, lower airway spasm, and effects of carbon monoxide poisoning. The second stage occurs after 3 to 4 days and consists of decreased oxygen levels and congestion within the lung tissue (diffuse lung infiltrates). The last phase starts about 3 to 10 days after the injury and consists of bronchitis and pneumonia. The focus of treatment differs from phase to phase.

Incidence and Prevalence: Among individuals in the US with burns over 5% of their total body surface area (TBSA), less than 10% have inhalation injuries; among those with burns over 85% of their TBSA, over 80% have inhalation injuries (Lafferty). In 2003, over 145,000 chemical burns were reported to the American Association of Poison Control Centers, of which 370 cases resulted in major chemical toxicity and 9,368 resulted in moderate chemical toxicity (Cox).

Source: Medical Disability Advisor



Causation and Known Risk Factors

Men are more likely than women to die from fire by a ratio of 3:2; both children and the elderly are also at increased risk for fire-related injury (Lafferty). Exposure rates for chemical burns are similar in adults and children, but burns from certain chemicals such as hydrofluoric acid are more common in men due to occupational exposure (Cox; Wilkes).

Source: Medical Disability Advisor



Diagnosis

History: Inhaling smoke or toxic chemicals can lead to burns in the upper and lower airway. After being trapped in a fire in an enclosed space, individuals may present with singed nasal hairs, wheezing with increased sputum, and burns to the inside of the nose, face, and oropharynx. Cough, dizziness, headache, pain in the chest, and vomiting (emesis) may all be present. These complaints may occur as late as 24 to 36 hours after the individual was caught in a fire. Individuals with chemical inhalation burns may present with laryngitis, shortness of breath (dyspnea), and chest pain, and may report having spilled a toxic chemical or use of inadequate protective gear while handling known caustic agents.

Physical exam: Airway, breathing, and circulation (ABCs) need to be checked in a fire or toxic chemical victim. A thorough neurological exam should be obtained. A lung exam may be positive for increased respiratory rate, wheezing, or crackling sounds (rales) and coarse gurgling sounds (rhonchi) in the lung that are associated with edema, all signs that the individual is having respiratory difficulty.

Tests: Electrolytes, lactate level, arterial blood gas (ABG), creatine kinase (CK), carboxyhemoglobin (COHb) level, and urine myoglobin are helpful tests if the individual has extensive burns. Fiberoptic bronchoscopy may be used in order to view the airway and assess the extent of injury. Imaging studies should include chest x-ray, as well as a xenon ventilation perfusion (VQ) scan, which can help identify lung pathology not visualized by bronchoscopy. Pulmonary function tests and electrocardiogram (ECG) can also be obtained.

Source: Medical Disability Advisor



Treatment

In individuals with trauma to the upper airway, intubation with mechanical ventilation is indicated. Intubation is needed in 50% of individuals with smoke inhalation. Positive end-expiratory pressure (PEEP) has been demonstrated to be associated with a positive outcome. Since carbon monoxide (CO) toxicity is a leading cause of death associated with fires, CO toxicity must be monitored by measuring the carboxyhemoglobin (COHb) level. The COHb level should be under 10%; 100% oxygen is given until that level is achieved. If an individual has neck burns, a tracheostomy may be necessary. Individuals with deep circumferential burns of the neck and / or trunk that can restrict breathing as tissues swell may require surgical incision and release of the soft tissues (escharotomy); if surgical bleeding is profuse, a blood transfusion may be performed. Hyperbaric oxygen is given if the individual's COHb is very high and if there is increased carbon dioxide and low blood pH secondary to hypoventilation of the lung (metabolic acidosis).

Intravenous (IV) fluids are very important. Generally, within the first 24 hours the healthcare professional should follow the Parkland formula, a protocol of infusing 4mL of fluid per kg body weight per percentage of the total body surface area (TBSA). However, with inhalation injury this formula may sometimes cause overhydration. IV fluids are needed if the burn covers over 20% of the TBSA.

If the individual has cyanide (CN) toxicity, treatment includes giving an antidote to create an alternate binding site for the cyanide; typically, amyl and sodium nitrite and sodium thiosulfate will bind to cyanide and convert it into a nontoxic compound that may be excreted through the kidneys. Individuals that develop methemoglobinemia may require an additional antidote of methylene blue to regain normal hemoglobin function.

Individuals need to be admitted to the hospital if they have any of the following symptoms or findings: facial burns, bronchospasm, pain upon swallowing, acidosis, particles of soot in the sputum (carbonaceous sputum), COHb greater than 15%, inhalation of a known highly caustic acid or base chemical, or lengthy exposure time (>10 minutes) during the injury.

Source: Medical Disability Advisor



Prognosis

Recovery from smoke inhalation depends upon severity of inhalation burn, associated injuries, and speed of medical treatment. Usually, most smoke inhalation burns cause no lasting effects and will resolve within 48 to 72 hours, with an overall mortality of less than 10% (Lafferty). Of all deaths caused by fire, 75% are due to inhalation burns; individuals with inhalation injuries alone have a 7% death rate, but it rises to 29% if the individual has thermal burns plus inhalation injury (Lafferty).

Prognosis for chemical inhalation injury depends upon the type of chemical inhaled, length of exposure, and extent of injury. Of the more than 145,000 cases of chemical burns reported in 2003, 33 cases resulted in death (Cox). Prognosis following hydrofluoric acid inhalation is poor (Wilkes).

Source: Medical Disability Advisor



Complications

Complications include a narrowing of the airway below the epiglottis of the larynx (subglottic stenosis), long-term bronchiole dilation from the injury (bronchiectasis), pulmonary edema, pneumonia, atelectasis, asthma, bronchospasm, and extreme difficulty breathing. Individuals may have upper airway injury with runny nose (rhinitis), infection of the sinuses (sinusitis), or hole in the nasal septum (nasal perforation); reactive airways dysfunction syndrome (RADS); pharyngitis; laryngitis; narrowing of the airway (stricture); and fistulae (abnormal tissue that joins different parts of the body). Chronic respiratory problems may occur in individuals with prior pulmonary disease or asthma.

Source: Medical Disability Advisor



Ability to Work (Return to Work Considerations)

The severity of the injuries will determine whether the individual returns to work. Individuals may need to miss work for appointments with doctors or psychotherapists. If the toxic exposure was work-related, the workplace may need to be assessed for safety.

Source: Medical Disability Advisor



Failure to Recover

If an individual fails to recover within the expected maximum duration period, the reader may wish to consider the following questions to better understand the specifics of an individual's medical case.

Regarding diagnosis:

  • What agent caused the inhalation injury?
  • What type of burn did individual suffer, thermal or chemical?
  • What parts of the body did the burn affect?
  • If individual was in a fire, did he or she inhale smoke?
  • Was the place where the fire occurred open or closed?
  • What types of materials were in the fire?
  • Does individual have any comorbid medical conditions?

Regarding treatment:

  • Did individual receive mechanical ventilation or intubation?
  • Did individual receive 100% oxygen?
  • Did individual receive hyperbaric oxygen?
  • Was a tracheostomy or escharotomy performed?
  • Did individual receive IV fluids?
  • Was individual admitted to the hospital?
  • Has individual been seen by a surgeon?
  • Has individual been treated in the burn unit?

Regarding prognosis:

  • Does individual have chronic exposure to the agent that caused the injury?
  • What systems have been affected by the inhalation burns?
  • Has individual suffered complications such as respiratory difficulties that may prolong recovery?
  • Will individual benefit from seeing a psychotherapist for any psychological problems that may developed as a result of the injury?
  • Has individual been compliant with outpatient follow-up appointments and treatment?

Source: Medical Disability Advisor



References

Cited

Lafferty, Keith A. "Smoke Inhalation." eMedicine. Eds. Daniel J. Dire, et al. 1 Aug. 2001. Medscape. 3 Aug. 2004 <http://emedicine.com/emerg/topic538.htm>.

Source: Medical Disability Advisor






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