Nitrous oxide antinociception in rats was evaluated by the warm water tail withdrawal test following central pretreatment with blockers of various opioid receptor subtypes. The analgesic dose, 50% (AD50) value for nitrous oxide antinociception was significantly elevated by MR-2266 (which is relatively selective for kappa-opioid receptors) and increased to a lesser degree by ICI-174,864 (which is selective for delta-opioid receptors). However, pretreatment with beta-funaltrexamine (which is selective for mu-opioid receptors), even at extremely high doses, was ineffective in altering the AD50 for nitrous oxide antinociception. According to these findings, nitrous oxide antinociception, as evaluated in this paradigm, appears to be mediated by kappa- and possibly delta- but not mu-opioid receptors.

Animals↗

PubMedDate not supplied

The effects of various dental procedures and patient behaviors upon nitrous oxide scavenger effectiveness.

This prospective study of 36 children, ages 44-93 months, receiving nitrous oxide-oxygen under standardized conditions during routine dental procedures was conducted to determine what influence eight selected dental procedures and three patient behaviors had on ambient nitrous oxide (N2O) levels in the dentist's breathing zone. Half the children received nitrous oxide-oxygen via a scavenging nasal mask. An infrared spectrophotometer analyzed the ambient N2O level continuously throughout the procedure and the time-weighted average (TWA) for consecutive 15-sec intervals was recorded by a microprocessor. A video camera was used to synchronize the coded dental procedures and patient behaviors to the TWA ambient N2O levels recorded. The results demonstrated that scavenging significantly reduced the dentist's exposure to ambient N2O (P less than 0.05, nonscavenged mean = 284.7 ppm; scavenged mean = 36.6 ppm), but the mean TWA N2O concentration remained significantly higher, P less than 0.05, than the 25-ppm level recommended by the National Institute for Occupational Safety and Health (NIOSH). Supplemental oral evacuation was the only dental procedure capable of reducing ambient N2O to below NIOSH's recommendation when scavenging was employed. The administration of local anesthesia consistently created a significant increase in ambient N2O levels. Patient behaviors of talking, crying, and movement also resulted in significant increases from baseline ambient N2O levels.

Air Pollutants, Occupational↗

PubMedDate not supplied

Pediatric dental emergencies.

Odontogenic infections and orofacial trauma are the most common types of pediatric dental emergencies. The avulsion of a child's permanent tooth or spread of an odontogenic infection through facial planes present serious medical problems requiring expedited care to achieve a favorable prognosis.

Child↗

PubMedDate not supplied

Ambient nitrous oxide levels during pediatric sedations.

Various studies have implicated generalized health problems with chronic exposure to trace levels of nitrous oxide. Recent investigations have reported that higher-than-recommended levels of nitrous oxide exist in the breathing zone of the dental staff. This study was undertaken to accurately determine waste nitrous oxide levels during pediatric sedations and to evaluate the effect of scavenging in reducing environmental exposure. Conscious sedations were performed on 20 uncooperative 2-4-year old children. Each child was assigned randomly to one of two groups, a scavenged group and a nonscavenged control. Sedations were accomplished with oral administration of chloral hydrate and hydroxyzine. All patients received nitrous oxide (40%) in oxygen throughout the procedure. Waste nitrous oxide levels were monitored 22-24 in from the dentist's nose using an infrared spectrophotometer and recorded by a microprocessor. Results indicate that environmental levels of nitrous oxide exceed the National Institute for Occupational Safety and Health (NIOSH) recommendations by 12 times, regardless of whether a scavenging system was employed or not. It is concluded that the scavenging system tested in this investigation may not be as efficient as previously thought at complying with NIOSH recommendations.

Air Pollutants, Occupational↗