A company that supplies equipment to the University Hospitals fertility center said its storage tank did not malfunction. "The early stages of our investigation into this unfortunate incident indicate it was the result of human error," Custom Biogenic Systems said in a detailed statement sent to News 5.
In a letter to patients on March 26, University Hospitals said that a remote alarm system on a storage tank that was designed to alert a University Hospitals employee to changes like temperature swings was turned off. UH said that on the evening of Saturday, March 3, the temperature inside the tank, which contained thousands of eggs and embryos, rose. UH does not know when the alarm was turned off. During the period when the alarm was off, UH said it had been experiencing "difficulty with what is called the liquid nitrogen automatic fill on the storage tank" for "several weeks."
Liquid nitrogen is added to the storage tank to keep specimens frozen, and it can be added manually or automatically.
According to UH, "We had been working with the tank manufacturer who had previously provided instructions on the necessary maintenance to 'thaw' the storage tank to correct this difficulty. To do that required transferring all specimens to an extra storage tank previously provided by the manufacturer. This process takes several weeks, and had begun when this event occurred, though no eggs or embryos had yet been moved to the extra tank."
Custom Biogenic Systems, of Bruce Township, Mich., says the extra tank was available to UH on Aug. 15, 2017, UH finalized its arrangements for delivery of the tank on Oct. 27, 2017, and the tank was delivered on Nov. 2, 2017. That's almost four months to the day before 950 UH patients lost 4,000 eggs and embryos in an event the hospital would later call "catastrophic."
With the automatic fill not working on the original tank, UH added liquid nitrogen to the tank manually. This was done by connecting the storage tank with a line to a tank of liquid nitrogen from the Embryology Lab.
But, according to UH, "For several days prior to the weekend in question, a manual fill could not be done using the line in the Embryology Lab because there were no liquid nitrogen tanks available. So, containers of liquid nitrogen were obtained from the Andrology Lab. Those containers were then manually poured into the top of the tank, while amounts of liquid nitrogen and temperature were monitored."
Custom Biogenic Systems says its tank is not designed to be filled by liquid nitrogen poured into the top of the tank.
The company said its product manual states:
"IMPORTANT: It is not recommended to attempt to manually fill the Isothermal Storage Unit by opening the lid and placing a fill line over the edge into the vessel. This is an incorrect fill method and will cause liquid nitrogen to come into contact with the stored samples."
The manufacturer also said, "The CBS (Custom Biogenic Systems) unit at UH is not designed to detect or monitor liquid nitrogen levels for any amounts of liquid nitrogen 'poured into the top of the tank.' The liquid nitrogen level read-out on the tank does not measure the level of liquid nitrogen in the storage area of that tank because liquid nitrogen should not be poured into the storage area of the tank. Rather, the read-out measures the level of liquid nitrogen in the liquid nitrogen reservoir, which was bypassed by UH's use of the 'container filling' method."
This video from Custom Biogenic Systems explains how temperature is regulated in its Isothermal Storage Unit.
In its March 26 letter to patients, UH said, "We do not yet know if this fill process may explain the rise in temperature over the weekend."
University Hospital officials have taken responsibility for the outcome and say they are still investigating the cause.
In its statement, Custom Biogenic Systems said the following:
CBS does not provide or service liquid nitrogen tanks. Accordingly, CBS was not at fault for the absence of liquid nitrogen tanks in the Embryology Lab.
CBS did not design, manufacture, install, control, or monitor the remote alarm system that was reportedly "off" during the time of this incident.
When the temperature began to rise on Saturday night (March 3), the CBS unit functioned properly by indicating a high-temperature condition and activating a local alarm. CBS is not responsible for the alert not being sent to the UH employee or for staffing of the UH lab, both as referenced in the UH letter.
In its statement, the company said, "CBS continues to have the utmost confidence in our products and the people who serve our customers. We are working diligently to support the investigation of what occurred at UH."
News 5 Cleveland has reached out to University Hospitals for comment.