PubMed · 7048693
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J V Warren. 1982. John Gorrie.. https://pubmed.ncbi.nlm.nih.gov/7048693/
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Epidemiologic studies have shown that trace concentrations of inhalation anaesthetics polluting the air of operating theatres could have deleterious effects on the personnel's health. Nitrous oxide (N2O) oxidises vitamin B12 and thus decreases DNA production by inactivation of methionine synthase. Therefore, the United States and most European health authorities recommend threshold values to protect against potential health risks. These values range from 25 to 100 ppm, expressed as time-weighted averages (TWA). There is a lack of data concerning measurements of trace concentrations under defined conditions. The aim of this study was to quantify levels of N2O in a recovery room (RR) with an air conditioning system. METHODS. Trace concentrations of N2O were determined in the main RR of the University Hospital of Regensburg (Germany). Measurements were taken for 5 days from 8:00 a.m. to 8:00 p.m. Trace concentrations of N2O were measured directly by means of a highly sensitive photoacoustic infrared spectrometry analyser. The lower detection limit was 0.03 ppm. Samples of room air were taken continuously from six different places in the recovery room, five of which had a distance of 50 cm to the patients' heads. One point represented the nurses' desk 5 m away from the patients. TWAs were calculated for each day and location. RESULTS. All values were below 5 ppm TWA at each location. Typical TWA (range) values recorded at day 2 were for point 1:3.5 ppm (0.4-8.9), point 2:3.2 (0.5-7.3), point 3:3.0 (0.5-5.4), point 4:3.7 (0.5-21.2), point 5:3.2 (0.6-6.6), and at the nurses' desk 3.3 (0.5-6.3). Peak concentrations of nearly 25 ppm were reached for at least 10 min. Significant differences between the days and locations could not be found (P < 0.05, Wilcoxon test). CONCLUSION. Exposure to N2O in a climatised RR is determined by several factors: (1) efficacy of air conditioning, with 10.7 changes per hour without recirculation; (2) recovery room size; (3) transport of the patients takes about 15 min, during which some quantities of N2O leave the patient; and (4) high numbers of patients staying 2 and more hours in the recovery room and exhaling smaller concentrations of N2O into the room air. Because of these factors, all measured values are significantly below the standard international threshold values. Under other conditions of room design, such as ventilation and size, measured values may be higher.
This study was done to measure the effect on inspiratory carbon dioxide (CO2) levels of infants exposed to the infant Crib Air (ICA) apparatus, a novel device which circulates room air within the infant's crib. Twenty-one healthy, sleeping infants and neonates (mean age = 14.7 weeks) were studied in a prospective crossover trial. All infants were studied lying face down or with the face placed passively to the side in their cribs. Inspiratory CO2 levels were recorded over a 30 minute period by measuring the concentration of CO2 immediately adjacent to the infants' nose and mouth. During the first 15 minute period, the baseline concentration of inspiratory CO2 was recorded. The infants were then exposed to the ICA apparatus in their cribs for 15 minutes and the concentrations of inspiratory CO2 were measured. Mean inspiratory CO2 levels in infants lying face down decreased from 8.5 to 1.4 mm Hg after ICA exposure (P < 0.001). Infants studied with their face placed passively to the side experienced a similar decrease in inspired CO2 concentrations. We conclude that the level of inspired CO2 by sleeping infants can be significantly reduced by the ICA regardless of the position of the infant's head.
Legionella pneumophila serogroup 1 strains isolated from a cooling tower during the investigation of an outbreak of Legionnaires' disease were shown previously to be related closely or indistinguishable by hybridisation-based restriction fragment length polymorphism analysis. However, these strains could be differentiated into five different MAb subgroups by comparison of their reactivity patterns with a recognised panel of monoclonal antibodies (MAbs). Pulsed-field gel electrophoresis (PFGE) of genomic fragments obtained after cleavage with rare-cutting restriction endonucleases also differentiated these strains. Four different restriction patterns were obtained with SfiI, EagI and SmaI, three restriction patterns with NotI, ApaI and SacII, and two patterns with NaeI. Generally, the restriction patterns were related closely, differing in only one or two bands. The combined results of the restriction endonuclease digestions allowed the strains to be differentiated into groups that correlated to the MAb subgroups. Both PFGE patterns and MAb subgroups were found to be stable markers. The findings demonstrated that the MAb variability seen amongst the L. pneumophilia serogroup 1 strains from this cooling tower was not solely phenotypic.