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    Product reviews: Pro-Nox and Alexis CES



    The views of the author are personal opinions and do not necessarily represent the views of Contemporary Ob/Gyn. Dr. Greenberg personally tests all the products he reviews. He has no conflicts of interest to report with respect to the content of this article.



    Like sushi, cappuccino and The Office, many ideas need to be foreign standards for a long time before Americans cotton to them. Such was the case in obstetrics with inhaled anesthetics for relief of labor pain. Use of nitrous oxide for analgesia during childbirth was first described by Dr. Stanislav Klikovich in Russia in 1881.1 Although inhalational N2O for parturients has been in wide use in the UK for well over 100 years, it was almost nonexistent in the United States until recently. In July 2013, the Pro-Nox Nitrous Oxide Delivery System was cleared by the FDA for sale in the United States and it is now readily available for American women.


    The Pro-Nox Nitrous Oxide Delivery System is a patient-controlled inhaled analgesia system that delivers a 50% oxygen and 50% nitrous oxide mixture for the relief of pain and anxiety. While at first glance the system’s tanks and tubing give it the appearance of a miniature petrochemical refinery, the system is actually fairly simple and has several important safety features built in. First, the system is 100% pneumatically driven, which means that it is fully portable without the need for plug-ins and can be easily moved as needed. Second, it is designed with a single-patient-use circuit that attaches to an internal demand valve to ensure minimal risk of infection between patients. Third, it comes with a variety of options (such as an active or passive scavenger system or wall mounts) to accommodate different labor settings. And, most importantly, it has an automated safety shut-off system that prevents improper gas mixtures in the event that either the oxygen or nitrous oxide tanks are empty or fail.

    In use on our labor floor, the Pro-Nox has pretty much been a winner. For the right patient, it is great and provides the labor analgesia option that we had been lacking (something between intravenous/intramuscular narcotics and an epidural). It is portable and easy to set up in cases such as the multip with active labor. It is safe and, it is effective for the right person. The only real complaints surround the tanks and valves, which can be persnickety to change over. But, the system is pretty gas-frugal so these changeovers are not too frequent.


    It seems a bit awkward to call a technology introduced in 1881 innovative in 2015 but the people at CAREstream do deserve some “attaboys” for building a system that fits comfortably on a modern labor floor governed by rigorous patient-safety and Occupational Safety and Health Administration regulations. Although Pro-Nox is far from the first system to deliver nitrous oxide for analgesia, it has lowered the bar sufficiently to encourage universal use of this option in the United States.


    James Greenberg, MD
    Dr. Greenberg is Chief, Division of Gynecology, Brigham & Women’s Faulkner Hospital, and Associate Professor, Harvard Medical School, ...


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