Nitrous oxide exposures during cryosurgical procedures

Details

• Corporate Authors:
  National Institute for Occupational Safety and Health
• Description:
  The results of NIOSH surveys of nitrous-oxide (10024972) exposures during cryosurgical procedures were presented. Environmental surveys were conducted at two facilities that used nitrous-oxide as the cryogenic gas in their surgical instruments. These instruments consisted of one or two 20 pound D-type cylinders connected to cryogenic probes by way of appropriate tubing and fitting. Neither instrument was vented. Nitrous-oxide exposures were measured during simulated and actual cryosurgical procedures using a portable infrared analyzer. The simulations were based on observed or reported work practices. Nitrous-oxide concentrations during a simulated procedure at the first facility (facility-A) that used a 4 minute freeze, followed by an 8 minute thaw and another 3 minute freeze peaked at 17,000 parts per million (ppm). This was equivalent to a 25 minute time weighted average (TWA) exposure of 7500ppm and was well above the NIOSH recommended standard of 25ppm. Assuming that no other nitrous-oxide exposures occurred, this exposure was equivalent to an 8 hour TWA exposure of 390ppm. At the second facility, a simulated procedure using a 3 minute freeze produced a peak nitrous-oxide exposure of 13,000ppm. This was equivalent to a 15 minute TWA exposure of 4000ppm and an 8 hour TWA exposure of 130ppm. Nitrous-oxide migrated into adjacent areas at both facilities. During two actual procedures at facility-A, nitrous-oxide concentrations of 195 and 140ppm were measured at a nurses station a short distance away. Measurements taken in an examination room after an actual procedure was performed at facility- A indicated nitrous-oxide concentrations still above 25ppm 70 minutes later. The author concludes that extremely high short term exposures to nitrous-oxide can occur during cryosurgery procedures. These exposures can be reduced by using local exhaust ventilation. [Description provided by NIOSH]
• Subjects:
  Health Personnel Nitrogen Oxides Occupational Exposure Occupational Health Safety
• Keywords:
  Compressed-gases Cryotherapy Health-care-personnel NIOSH-Author Nitrogen-oxides Occupational-exposure Simulation-methods Surgery
• ISSN:
  1047-322X
• Document Type:
  Text
• Genre:
  Journal Article
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  7
• Issue:
  11
• NIOSHTIC Number:
  nn:00211680
• Citation:
  Appl Occup Environ Hyg 1992 Nov; 7(11):721-723
• CAS Registry Number:
  Nitrous oxide (CAS RN 10024-97-2)
• Editor(s):
  Tharr D
• Federal Fiscal Year:
  1993
• Peer Reviewed:
  True
• Source Full Name:
  Applied Occupational and Environmental Hygiene
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:b8e080820d1fa345244deb97b03486a8284e0d3aa75333abeae4cbfd0b82767254002aac926590d03d470c0dc24401ba1d7868150f2ad415eb2176c2730b5c9a
• Download URL:
  https://stacks.cdc.gov/view/cdc/205202/cdc_205202_DS1.pdf
• File Type:
  [PDF - 431.64 KB ]