The Science Journal of the American Association for Respiratory Care
Background: As an essential hospital facility, the central oxygen supply system should be designed with features allowing back-up and/or redundancy in the event of system failure. For example, the availability of a back-up supply would be especially important if the main supply line from the bulk liquid storage to the main hospital were a single feed line at risk of being disrupted by mishaps such as road construction, natural disasters, etc. As part of an organized institutional review of The Cleveland Clinic Hospital in-patient central oxygen supply system, we undertook a survey of all hospitals in two Ohio cities (Cleveland and Columbus) to determine the characteristics of hospital central supply systems in 1999.
Methods: The questionnaire was developed and completed by structured telephone interview during calls placed to managers of facilities engineering departments in all hospitals in the greater Cleveland and Columbus (Ohio) metropolitan areas. To encourage candid responses to the phone interview, respondents were assured that institutional identifiers would not be presented in published reports. The questionnaire addresses the type of primary and reserve oxygen sources in the hospital, whether a back-up system exists, and if so, in what configuration. The questionnaire also addresses whether any unplanned interruption or other problem (such as contamination of the piped-in oxygen supply) had ever occurred in the facility. When the manager of the hospital facilities department could not be reached, follow-up calls for questionnaire completion were placed to the hospital directors of respiratory care.
Results: Of the 35 eligible hospitals, surveys have been completed in 23 (66%) to date. The mean number of beds in the hospital surveyed was 336 (± 191 SD) and the original construction dates of the surveyed hospitals ranged from 1887 to 1982. Of the 23 hospitals, all have central oxygen supplies that rely on a bulk oxygen system consisting of a primary liquid reservoir with an additional liquid reservoir or manifolded gas cylinders functioning as a reserve. Eighteen (78%) of those surveyed have the reserve supply, liquid or manifolded cylinders, at the same location as the primary liquid vessel. The supply lines of these contiguous primary and reserve containers join proximal to entering the hospital structure, so that the main and the reserve supply of these eighteen hospitals are dependent upon a single length of pipe. In the remaining 5 institutions, 4 have manifolded cylinders that have a physically separate feed line and 1 has no on-line back-up but relies on portable cylinders. Presented with the possibility of an interruption of service of the liquid bulk supply, many of the hospitals surveyed (14/23, 61%) depend on the ability of their liquid oxygen supplier to provide a portable tanker and evaporator to be connected to an interface on the facility exterior. Respondents estimated that it would take 45 minutes to 2 hours before a tanker could be in place and on-line. Finally, of the 23 hospitals surveyed, 4 (17%) reported having experienced temporary interruption in service from the bulk liquid supply. In each of these incidents, a contractor had damaged the incoming supply line.
Conclusions: 1. Most of the hospitals in these two urban areas use bulk liquid oxygen systems as the main central supply source, with some providing manifolded cylinders as back up. 2. Mishaps regarding the bulk oxygen central supply system were reported by 17% of responding institutions and all involved interruption of the incoming supply line. 3. The fact that most main and reserve tanks were contiguous and fed through a single line to the hospital facility suggests ongoing risk for interruption of an oxygen supply by line mishaps (e.g., construction). 4. Contingency planning to lessen the risk of an interrupted supply should involve back-up systems with physically separated feed-lines, as well as banks of manifolded cylinders along the course of the main hospital oxygen circuit line.