Poorly Ventilated Research Articles

One-stage revision surgery for pediatric cholesteatoma: long-term results and comparison with primary surgery

Objective: Few studies report on revision surgery for pediatric cholesteatoma, even if most studies of primary surgery show high recurrence rates. We present independently evaluated long-term results of revision surgery and compare the results with those of primary surgery. Methods: The series consisted of 42 consecutive pediatric (age <16 years) cholesteatoma revision operations in the Helsinki University ENT Department. The primary and revision surgery was non-staged, all mastoids were obliterated and the bony ear canals were reconstructed. The preoperative, surgical and annual control data were recorded in a database. The last control was independently performed (J.S.) with an average follow-up of 4.3 years and 87% attendance. Results: The recurrence rate for revision operations was 38%. A retraction process developed in 38% of the ears and 67% of these retractions turned into active cholesteatomas. There was a non-significant difference for these figures as compared with primary surgery. Postoperative discharge and poor middle ear ventilation were associated with recurrence. The following factors showed significant differences between primary and revision surgery: increased number of bare facial nerve in the revision group, lower recurrence rate for experienced surgeons (as for both groups together) and improved hearing results for ears without recurrence in the revision group. Conclusions: Recurrent disease after revision surgery appears either in the attic or in the mesotympanum, or develops from a retraction pocket in a similar manner as was seen in patients receiving primary surgery. Recurrence is associated with discharging and poorly ventilated ears. Pediatric cholesteatoma surgery should be done or be supervised by experienced surgeons. The present operation methods result in many recurrences after primary and revision surgery. New surgical methods are needed to create additional aeration pathways to the epitympanum in order to improve middle ear aeration and to prevent some of the retractions.

Emission testing and inhalational exposure-based risk assessment for candles having Pb metal wick cores

Segments of seven candles with wicks having a Pb metal core have been tested in a purpose-built combustion chamber to assess air Pb emissions. Emissions were collected on glass fibre filters that have been digested in concentrated HNO 3 and analysed by flame atomic absorption spectroscopy (FAAS). Despite an indication of a bimodal distribution in Pb emission rates, and a range from 450 to 1130 μg Pb/h, the mean rate from the seven candles was 770 μg Pb/h. The 38-cm long candles are, on average, capable of emitting 104 000 μg of Pb into the air over ∼127 h. A mean value of 20% of the Pb metal in the wick consumed by the candle is emitted into the air, the remainder appears to accumulate at the base of a molten wax-pool adjacent to the wick. Individual Pb-bearing particles from the combustion of candles were observed in a field emission scanning electron microscope (FESEM) to have a diameter of 1 μm or less. The emission from the candles has been analysed by X-ray diffraction (XRD) and identified as Sodium Lead Carbonate Hydroxide [NaPb 2(CO 3) 2OH]. This compound, being a Pb carbonate, is likely to be easily absorbed in the lungs and gastrointestinal tract. Risks associated with inhalational exposure have been assessed after determining indoor lead in air (PbA) concentrations. Given a lack of information on the duration of use of candles, a range of scenarios from worst possible case to daily and weekly burning regimes are evaluated. Detailed evaluations of PbA are based on the emission from a single candle at rates of 500 and 1000 μg Pb/h, room volumes of 25 and 50 m 3, durations of emission of 1.5, 3 and 6 h and air infiltration rates of 0, 0.25, 0.5, 0.75 and 1.0 air volume changes per hour (ACH). A candle burnt for 3 h at 1000 μg/h in a 50 m 3 room having poor ventilation at 0.25 ACH is estimated to yield a 24-h average lead in air concentration of 9.9 μg/m 3 with a peak PbA value of 42.1 μg/m 3. Daily exposure to such candle burning where children spend 80% of their time indoors is likely to elevate PbB in children by a minimum of 24 to 40 μg/dl, according to the PbB:PbA relationship of Brunekreef, 1984 (The relationship between air lead and blood lead in children: a critical review). Estimating child Pb uptake from first principles using a range of exposure factors, a child would obtain some 85 to 127% of the provisional tolerable weekly Pb intake (PTWI) from such daily exposure. Child blood lead levels could readily exceed levels of 10 μg/dl, largely due to exposure to emissions from burning Pb wick core candles for several hours once per week. The regular burning of multiple candles in small, poorly ventilated spaces could readily be associated with clinical Pb poisonings and death. High levels of exposure could occur with Pb metal core wick candles in less developed countries where candles are used on a daily basis for indoor lighting purposes in small dwellings. Prolonged burning of candles may occur in religious and in ceremonial circumstances or restaurants where they may be of particular concern. On the basis of the limited investigation carried out, candles having a wick with a Pb metal core have the potential to present highly unacceptable and avoidable risks to human health.

Effect of Formaldehyde Exposure in the Hatcher and of Ventilation in Confinement Facilities on Broiler Performance

Broiler embryos and chicks were exposed to formaldehyde vapors (up to 130 ppm) during the final 3 days of incubation. Bacterial load was significantly lower in a formaldehyde-fumigated hatcher than in an unfumigated hatcher. Hatchability was not affected. To determine if exposure to formaldehyde vapors in the hatcher would affect broilers' ability to tolerate variations in air quality, chicks were placed in either adequately or poorly ventilated confinement facilities for 45 days. Total and respirable dust particles (< or = 5 microns in diameter) increased to a greater extent between 5 and 6 weeks of broiler age in the poorly ventilated facility than in the facility with adequate ventilation. Mortality at 6 weeks of age was significantly higher in broilers exposed to formaldehyde in the hatcher and housed with poor ventilation than in broilers exposed to formaldehyde and raised with adequate ventilation. Six-week body weight, feed conversion, and septicemia/toxemia condemnations were adversely affected by poor ventilation. This study found that the quality of air in the confinement facility had a greater influence on broiler productivity than did exposure to formaldehyde vapors in the hatcher.