End-tidal and blood halothane and nitrous oxide in surgical personnel

Solid-phase microextraction gas chromatographic-mass spectrometric method for the determination of inhalation anesthetics in urine

Solid-phase microextraction (SPME) has been applied to the headspace sampling of inhalation anesthetics (i.e. nitrous oxide, isoflurane and halothane) in human urine. Analysis was carried out by gas chromatography-mass spectrometry using a capillary column with a divinylbenzene porous polymeric stationary phase. A SPME divinylbenzene-Carboxen-polydimethylsiloxane coated fiber, 2 cm long, was used, and its performances were compared with those of a Carboxen-PDMS in terms of sensitivity, extraction efficiency, extraction time, fiber coating-urine distribution coefficient. For both fibers, linearity was established over four orders of magnitude, limits of detection were below 100 ng/l for nitrous oxide and below 30 ng/l for halogenated. Precision calculated as %RSD was within 3-13% for all intra- and inter-day determinations. The method was applied to the quantitative analysis of anesthetics in the urine of occupationally exposed people (operating room personnel).

A clinical evaluation of an operational postanesthesia care unit source control system

Various air safety hazards in the PACU and a number of attempts to cope with the hazards have been addressed (see J Peri Anesth Nurs 11:207, 1996). This article presents a clinical evaluation of an operational source control system developed specifically for use in the PACU. The criterion for evaluation was the degree to which the source control system could reduce the concentration of waste anesthetic gases released into the environment by the patient. The N2O molecule is a thousand times smaller than droplet nuclei that carry infectious respiratory disease. Thus, containment of waste gases may also indicate containment of pathogens. Twenty-two postsurgical patients were studied. The control group was given routine care with supplemental oxygen by nasal prong. The experimental group was given supplemental oxygen and had exhalent scavenged via the source-control system. Waste gas concentrations were monitored, and a criterion was applied to the data to determine the effectiveness of the source control group when compared to nasal prong group. The nasal prong group exceeded the compliance criterion 58% of the time. The source control group exceeded the compliance criterion at no time during the study. From these results, the source control system is effective at reducing concentrations of waste anesthetic gases allowed into the atmosphere of a room. Application of the source control to the PACU environment could prove valuable in addressing air safety hazards.

An evaluation of air safety source-control technology for the post anesthesia care unit

A new source-control system designed specifically to address the most important air safety hazards in the post anesthesia care unit (PACU) is presented--the transmission of bloodborne and respiratory pathogens, and occupational exposure to waste anesthetic gases. The controversy arising from research in the 1970s, 1980s, and 1990s regarding waste anesthetic gases, government regulations that responded to air safety hazards, and the resulting de facto use of scavenging systems in almost all operating rooms across the United States is discussed. However, a similar concern does not apply to the PACU although its unique characteristics make it an especially high-risk environment for air safety hazards.

The post anesthesia care unit: unique contribution, unique risk

The environment in the postanesthesia care unit (PACU) is unique in the modern hospital. It was born of necessity and continues of necessity. The modern PACU has evolved from a simple room designed to house a single patient and a nurse to a modern, bustling room of great proportions. Today's PACU is an open ward, probably the only one left in the modern hospital, and contains many immunocompromised patients, including pediatric patients; knowledge of the patient's medical history may be sketchy or brief. Patients undergo cough-inducing procedures and exhale waste anesthesia gases. The PACU has a high ratio of health care workers (HCWs) to patients. HCWs, often in their childbearing years, function in close proximity to the patient's face. These environmental conditions coupled with the epidemic proportions of tuberculosis in the United States, the increase in incidence of hepatitis C virus, the consequences of human immunodeficiency virus, and the possible adverse effects of waste anesthesia gases result in a milieu that is a risk to both patients and HCWs that cannot be managed with air exchange controls alone. This article reviews the historical contribution of the PACU and the factors in the PACU environment that increase the vulnerability of HCWs and patients to respiratory diseases, bloodborne pathogens, and adverse effects of waste anesthetic gases.

Evaluation of exposure to isoflurane (Forane): environmental and biological measurements in operating room personnel

The concentration of isoflurane (Forane) in the ambient atmosphere was determined in 11 operating theaters of 5 hospitals in Italy. The concentration of isoflurane in the ambient air exceeds the recommended time-weighted average exposure levels (median value: 113 mumol/m3). Isoflurane was detected in the urine of 45 exposed subjects (anesthetists, surgeons, and nurses). A significant correlation was found between the isoflurane concentration in urine produced during the shift (Cu' nmol/l) and isoflurane environmental concentration (Cl' mumol/m3) (Cu = 0.243 X Cl + 3.712) (r = .90). The results show that the urinary isoflurane concentration can be used as an appropriate biological exposure index. The authors suggest a biological exposure index of 18 nmol/l (3.4 micrograms/l). This is the biological value obtained after 4 h of an average environmental exposure to 81 mumol/m3 (2 ppm).

Non-polluting dental analgesia

Three anaesthetic circuits for use in nose-piece application of inhalation analgesia are described. An ejector flowmeter is used for the scavenging of overspill gas.

Concentration elimination of anaesthetic gases in operating theratres. Influence of anaesthesia apparatus leakages

Halothane and nitrous oxide (N2O) concentrations were measured in operating theatres, in the areas corresponding to theinhalation zones of the anaesthetists and operating nurses. The measurements were performed in an operating theatre with a non-recirculating air exchange rate of 20/h. This was performed partly in model experiments and partly during the administration of anaesthesia by intubation. In the model experiments. the measurements were taken both with and without a specially constructed scavenging system. During anaesthesia, the measurements were taken exclusively with the scavenging system, although well-defined leakages were fitted into the otherwise gas-tight anaesthetic system. The results were supplemented by smoke experiments which showed the air distribution patterns. The investigation showed that the gases were concentrated over and around the operating table. Activities during surgery diluted this concentration. Furthermore, it was shown that leakage in the anaesthetic system significantly influences the achieving of a low gas-air mixture. Halothane concentrations in the inhalation zone of the anaesthetist and operating nurse can be reduced to 0.02 and 0.01 p.p.m. respectively, if the anaesthetic system is completely gas-tight.

The dumping valve and its clinical application

An open reservoir for the collection and evacuation of anaesthetic gases permits leakage to room air. The use of a closed reservior for the removal of overspill gas from anaesthetic circuits is described. Calibrated gas evacuation is carried out through an ejector flowmeter from the anesthetic circuit or from a closed reservoir, where the gas is collected via a relief valve. In order to eliminate the risk of high or low pressure in the reservoir employed, a relief valve and a dumping valve is included in the system.