It is well known that people working in hospital-operating theatres are often exposed to anaesthetic gases. The system used to supply a mixture of anaesthetic gases to the patient consists of the anaesthetic machine and the anaesthetic breathing circuit. The amount of leaking anaesthetic gases contaminating the room can be traced back to a number of sources including the anaesthetist's work practice and anaesthetic equipment. Starting from the 1960s, adverse health effects were observed in medical personnel, mainly nurses, who had been working with anaesthetic gases particularly nitrous oxide and halothane. The associated health-risk was a result of inhaling the air, which has been contaminated by anaesthetic gases from air exhaled by patients and leakage from the equipment due to technical defects in the system. For this reason, many countries have imposed recommendations for the limits to exposure to nitrous oxide and other anaesthetic gases for already existing and for newly constructed or renovated operating theatres and stricter safety precautions at the beginning of the 1980s. In this paper, Nilsson et al. reviewed 31 scientific studies related to hazardous effects of exposure to volatile anaesthetic gases and found that currently used volatile anaesthetic agents have no conclusive mutagenic, carcinogenic, organ toxicity and adverse reproductive effects. The review conducted by Nilsson et al. provided further evidence that the health of workers exposed to volatile anaesthetic agents should not be adversely affected except for those who have been exposed to levels far exceeding the recommended levels in USA and Europe. However, some results seem to be inconsistent which may be due to insufficient exposure measure to determine dose–response relation (Hoerauf et al. 1999), absence of a more detailed measurement of exhaled air analysis to exclude accurately other interfering substances in the environment (Summer et al. 2003), uncontrolled confounding variables such as occupational stress, exposure to other contaminants including blood, radiation, drugs and aerosol sprays (McGregor 2000) and timing of biological monitoring such as blood, urine and breath samples (Raj et al. 2003).

Healthcare waste includes all the waste generated by healthcare establishments including its research facilities and laboratories. Generally, 75–90% of the waste products is considered non-risk while 10–25% is considered as hazardous health-risk. Of these health-risk waste products, only less than 1% is special waste including radioactive, cytostatic, and anaesthetic wastes (Prüss et al. 2001). Although the absolute risk of trace levels of waste anaesthetic agents remains unclear, certain symptoms such as general fatigue, exhaustion, loss of concentration, and headaches were found in some operating room personnel. In spite of this low health-risk and lack of conclusive evidence, healthcare facilities and administrators should not be complacent in developing occupational health and safety policies as there are possibilities that exposure even to trace concentrations of waste anaesthetic gases may cause health-risk of varying degrees. So far, research studies show that anaesthetic gases, particularly nitrous oxide, were found in higher concentration compared with other newer volatile gases such as isoflurane and sevoflurane. Raj et al. (2003) evaluated the exposure of paediatric anaesthetists to nitrous oxide and sevoflurane by monitoring their blood, urine and breath samples as well as environmental levels immediately after each induction, at middle of the operation lists and after the last induction. The operating room exposure value of nitrous oxide is 25 p.p.m. over an 8-hour period to prevent decrements in performance, cognition, audiovisual ability, and dexterity as recommended by the National Institute for Occupational Safety and Health (NIOSH), USA. Raj et al. found that exposure indices to sevoflurane were generally low compared with the control group. This result, however, contradicts with the findings of Summer et al. (2003), where they found that exhaled sevoflurane in the breath of 40-operating room personnel was significantly more at all times and more so after completion of duty as compared with 370 controls. This result was significant in that the effect was not only dose-dependent but also time-dependent indicating that the time span between cessation of duty and commencement of next duty period may not allow for complete elimination of inhaled anaesthetic agents from the circulation and more detailed measurement of exhaled air analysis was recommended.

Nilsson et al. recommended that occupational exposure to inhalation of anaesthetic gases should be minimized as it may lead to adverse health effects for the personnel exposed. The leaking of anaesthetic gases and pollution of the premises cannot be avoided. Other measurements have also shown that using a mask anaesthesia entails heavier exposure of personnel compared with exposure using insufflation anaesthesia. Many countries pay special attention to workers safety in operating theatres, which is leading to increased awareness of recommended exposure levels and measuring methods. The Centre for Disease Control and Prevention and the World Health Organization have published reports and guidance with regards to working with halothane, isoflurane, and other volatile gases. International agreements and legislative and regulatory principles have also been outlined in Prüss et al. (2001, p. 31) report especially with regards to health and safety precautions and the ‘duty of care’ principle that stipulates that ‘any person handling and managing hazardous substances or related equipment is ethically responsible for using the utmost care in that task’. There are, however, published general recommendations for safe work practices such as preventing gas leak by checking all rubber hoses, connections, tubing and breathing bags daily and replacing them when damaged or when recommended by the manufacturer. There should also be a well-designed waste anaesthetic gases scavenging system installed with the equipment with the outlet part of the scavenging system sufficiently large to impose the least possible load on the ejector. The Swedish Standard suggested a flow capacity not exceeding 50 l/minute measured at a flow resistance with a pressure drop of 1 kPa and not less than 25 l/minute measured at a pressure drop of 2 kPa. Panni and Corn (2002) suggested the use of anaesthetic scavenging hood that encloses the patient's head with a gas-impermeable flexible fabric bag. In testing its use, they found that it dramatically reduced the levels of anaesthetic contamination in the operating room well below the NIOSH standard level as well as conserved body heat. The use of intravenous Propofol in combination with low percentage of volatile anaesthetic via insufflation has also shown to decrease waste anaesthetic gas pollution in the operating room (Zestos et al. 2004).

The review presented by Nilsson et al. demonstrates the effectiveness of conducting a systematic review in providing evidence to what is little known about the phenomenon and the uncertainties that could trigger panic among operating room personnel. However, the review also highlighted the need for a more rigorous study on the effects of exposure to volatile anaesthetic gases taking into account the limitations in previous studies.


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  2. References
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  • Panni MK & Corn SB (2002) The use of uniquely designed anesthetic scavenging hood to reduce operating room anesthetic gas contamination during general anesthesia. Anaesthesia and Analgesia 95, 656660.
  • PrüssA, GiroultE, RushbrookP (eds) (2001) Safe Management of Waste from Health Care Activities. WHO Library – Cataloguingin Publication Data, Geneva.
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