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The environmental impact of anesthetic gases

May 22, 2012

Civil & Environmental Engineering Assistant Professor Matthew Eckelman is determining what type of effect that the anesthetic gases used in the healthcare industry have on the environment. Dr. Eckelman's research uses modeling tools to evaluate the life cycle effects of new materials, technologies, and policies on the environment and human health. He presented at the 2012 International Symposium on Sustainable Systems and Technology showing that even small amounts of anesthetic gases have a detrimental effect on global warming.

Source: News @ Northeastern

The poten­tial health impacts of cli­mate change are far reaching. Car­dio­vas­cular dis­ease, heat-​​related asthma and mal­nu­tri­tion due to com­pro­mised food secu­rity are just a few of the asso­ci­ated risks. The health-​​care system in which patients are even­tu­ally treated is respon­sible for 8 per­cent of the nation’s green­house gas emis­sions. According to civil and envi­ron­mental engi­neering assis­tant pro­fessor Matthew Eck­elman, this all raises the inter­esting ques­tion of how the health-​​care industry itself is affecting our health through direct and indi­rect changes in our environment.

Eck­elman looks at the life cycle of var­ious prod­ucts and processes — from pro­duc­tion to destruc­tion — to deter­mine their overall envi­ron­mental impact on a sys­tems level. In a recent paper in a spe­cial issue of the journal Anes­thesia & Anal­gesia, Eck­elman and col­leagues at Yale Uni­ver­sity per­formed life-​​cycle assess­ments of the major anes­thetic gases used in the health-​​care industry: nitrous oxide (laughing gas), des­flu­rane, isoflu­rane and sevoflu­rane, as well as a liquid anes­thetic alter­na­tive, propofol.

“Any life-​​cycle assess­ment, Eck­elman said, is a series of trade­offs. The health-​​care system is designed to reduce human mor­tality and mor­bidity, but it is also impor­tant to under­stand the indi­rect or unin­tended effects that health care has on the envi­ron­ment and public health. “The health-​​care sector is increas­ingly con­cerned with sus­tain­ability issues,” he said.

Life cycle green­house gas (GHG) emis­sions of anes­thetics, including waste anes­thetic gas emis­sions of halo­genated drugs and nitrous oxide (N2O).

During a talk at the Inter­na­tional Sym­po­sium on Sus­tain­able Sys­tems and Tech­nology in Boston last week, Eck­elman deliv­ered the paper’s results, showing the rel­a­tive envi­ron­mental pro­file of each anes­thetic alter­na­tive, and the impor­tant con­clu­sion that the com­bined envi­ron­mental impact of pro­duc­tion, trans­porta­tion, waste dis­posal and other life-​​cycle events pales in com­par­ison to the impact of the anes­thetic gases alone.

“Anes­thetic gases like nitrous oxide and the three halo­genated ethers are green­house gases them­selves,” said Eck­elman, who chaired a por­tion of the sym­po­sium, “and they’re quite potent.” Des­flu­rane, for example, has a global warming poten­tial more than 2,500 times that of carbon dioxide, he said.

Only small amounts of the gases are actu­ally metab­o­lized by the body. “The rest are usu­ally vented out of the top of the hos­pital.” In addi­tion to the anes­thetic itself, these agents require a car­rier gas, which can be oxygen com­bined with either air or nitrous oxide, said Eck­elman. In cases where nitrous oxide is used, a large por­tion of the impact comes from emis­sions of the car­rier gases.

Based on the research results, which put des­flu­rane at the top of the list in terms of life-​​cycle green­house gas emis­sions, Eck­elman and his team made a series of rec­om­men­da­tions for both doc­tors and hos­pi­tals. Within med­ical and cost con­sid­er­a­tions, they sug­gest doc­tors should avoid des­flu­rane where pos­sible; use oxygen as a car­rier gas instead of nitrous oxide; min­i­mize fresh gas flow rates; and employ IV anes­thetic alter­na­tives in applic­able cases — propofol’s envi­ron­mental impacts are neg­li­gible com­pared to the inhaled anesthetics.

The paper, which links health and sus­tain­ability, two of the university’s cen­tral research themes, is part of a gen­eral inter­na­tional effort to bring life-​​cycle assess­ment to bear on var­ious aspects of health-​​care prac­tice. Civil and envi­ron­mental engi­neering pro­fessor Matthew Eck­elman deliv­ered the results of an anesthetic-​​drug life-​​cycle assess­ment to the Inter­na­tional Sym­po­sium on Sus­tain­able Sys­tems and Tech­nology last week.

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