tion to avoid inhalational anaesthesia and use intravenous
agents instead [3], or use a separate anaesthetic induction
room before transferring the patient to the OR [33,34],
which is a traditional British anaesthetic practice [35].
However, according to Ref. [36] inducing patients in the
OR is not a problem, based on Canadian experience and
argues that the anaesthetic room is an expensive luxury and
a liability.
Air conditioning and an efficient pressure/exhaust
ventilation (412 ACH) together with efficient active
scavenging systems are sufficient to sustain N2O exposure
in ORs at levels below or within the OEL value of 180mg/
m3
[29]. However, even when scavenging systems and OR
air conditioning are used, N2O and volatile anaesthetic
pollution has been consistently detected in ORs [16].In
ORs with closed scavenging systems, N2O contamination
during mask anaesthesia frequently exceeds the maximum
recommended level of time-weighted concentration of
25 ppm (parts per million) by the US National Institute
for Occupational Safety and Health (NIOSH). In a
mechanical model of anaesthetic induction, turning the
gas flows off before intubation and leaving the vapourizer
on (the gas off practice) maintained postintubation end-
tidal drug concentrations close to preintubation equili-
brium and minimized OR pollution.
According to a literature review by Burm [22], typical
N2O concentrations measured in the 1970s in the breathing
zone of the anaesthetics were 1000–3000 ppm in ORs
without and 200–500 ppm in ORs with mechanical
ventilation. Corresponding halothane concentrations were
10–35 and 2–5 ppm, respectively. The use of scavenging
equipment systems reduced N2O concentrations to
100–300 ppm in unventilated and 15–35 ppm in ventilated
ORs, and corresponding halothane concentrations to 1–4
and 0.2–0.5 ppm, respectively. Nitrous oxide concentra-
tions, recently measured under different circumstances,
were generally below 100 ppm in scavenged mechanically
ventilated ORs and air-conditioned recovery rooms.
A study in 10 Japanese ORs where N2O was used in 402
cases [37], reported abnormally high N2O concentrations
(450 ppm) at some time during 25.9% of those cases, due
to: mask ventilation (40.4% of detected cases), uncon-
nected scavenging systems (19.2%), leak around uncuffed
paediatric endotracheal tube (12.5%), equipment leakage
(11.5%), and others (16.4%). An unconnected scavengingsystem led to the highest concentrations of N2O recorded.
Paediatric anaesthetists are at higher risk of exposure to
WAG, which often exceed set safety limits [38].
2.2. Disinfectants–sterilants
Aldehydic compounds (e.g. forlmadehyde and glutar-
aldehyde), which are used as disinfectants for cold
sterilization, may also have adverse health effects [28].
According to the World Health Organization (WHO) and
the Occupational Safety & Health Administration (OSHA)
[19], use or exposure to formaldehyde may cause acute
health effects including eye etching, headaches, nausea,
difficulty in breathing, dermal irritations and other
symptoms. High concentration of vapour inhaled for long
periods can cause chronic health effects including laryngi-
tis, bronchitis or bronchial pneumonia. Prolonged expo-
sure may cause conjunctivitis and it is a suspected
carcinogen. Glutaraldehyde can cause occupational asth-
ma, skin rashes, eye irritations, shortness of breath, chest
pain/discomfort, cough, fatigue, nausea and headaches.
Ethylene oxide, which is used as a disinfectant and
sterilant of surgery tools [28], is toxic and its acute health
effects include respiratory and eye irritation, vomiting, and 医院手术室室内空气英文文献和中文翻译(2):http://www.youerw.com/fanyi/lunwen_16710.html