Classic 02-N20 Pipe Switch Causes 2 Deaths Before Problem Caught
Medical gas supply to the anesthesia machine from a hospital pipeline still represents a hazard to patients.
A 77-year-old female was scheduled for orthopedic surgery to repair a broken leg on 21 December 1987 at a Japanese national hospital in Kyushu, Japan. A spinal anesthetic was given and during the intraoperative period she developed hypotension. She was given oxygen by mask as part of the usual cardiovascular support. Shortly thereafter, the patient developed the rapid onset of severe shock, did not respond to medications, and died of “acute heart failure.” An autopsy faded to reveal any pathological change to support the diagnosis of acute heart failure
Two days later, 23 December 1987, a nine-year old male was given a mixture of nitrous oxide and oxygen for urological surgery in the same room. The patient went into severe shock after the nitrous oxide was turned off. Death was attributed to “acute heart failure”.
The next day, 24 December 1987, a patient was scheduled for surgery in the same room (OR 2) under local anesthesia. When the surgeon asked for oxygen to be administered, the patient objected to the mask and refused. The attending physician then sniffed the gas to see if there was an odor and noted sensations which turned out to be nitrous oxide induced.
Police investigation of the deaths revealed a misconnection of the oxygen and nitrous oxide hospital pipelines. The hospital had remodeled OR I adjoining the previously remodeled and now active OR 2 and had failed to notify the Department of Anesthesiology of & intent to work on the hospital medical gas pipelines. New air conditioning ducts were installed in the ceiling and the medical gas pipelines had to be cut to facilitate installation (see diagram). The pipelines in question were not color-coded or identified in any fashion as containing oxygen or nitrous. Upon completion of remodeling, no tests were done at the OR 2 delivery site for nitrous oxide or oxygen. In addition, the anesthesia machines of the hospital did not have oxygen analyzers in use
A small company had contracted the remodeling construction. Inquiry found that the subcontractor for the welding of the pipelines had been given drawings by the hospital of the pipelines without identification of their contents. Those who provided the drawings did not recognize the critical nature of the gases contained within the pipelines and did not tell the subcontractor or the Department of Anesthesiology.
These deaths and subsequent investigation had a major impact throughout Japan. The Ministry of Health and Welfare immediately began to draft a Japanese Industrial Standard which, after its 1990 adoption, sets standards for medical gas pipelines.
Anesthesiologists must recognize the importance of observing what is happening in and around the operating room. Ask questions about remodeling and new construction. We cannot depend on the contractor, welding company, or hospital to inform us of intentions to tamper with the oxygen, nitrous oxide, compressed air, and/or suction lines. If there is any question, test each medical gas outlet to be sure the gas delivered is the gas intended. A simple oxygen analyzer will prevent a major catastrophe. Oxygen analyzers in the patient breathing system are essential but must be turned on! Hospital medical gas pipelines and cylinders must always be viewed with some degree of suspicion.
Patient safety must be foremost in our minds as we administer anesthesia. The two deaths described in this report emphasize the outcome which can result from unobserved factors outside our control when we are not sufficiently vigilant.
Dr. Sato is from the Department of Anesthesiology, School of Medicine, Tottori University, Tottod-ken, 683, Japan. Dr. Sato thanks Dr. Clayton Petty of the National Naval Medical Center in Bethesda, MD for his assistance.