HOSPITAL staff yesterday attacked the Red Cross for using an inferior alarm system on its fridges, leading to two days' supply of donated blood being thrown away. Some hospitals have altered their models from the one the Red Cross uses because of fears that a power loss could disable the alarm. The alarm - which should have alerted Red Cross staff to a change in temperature because the power had failed - was connected to the same power source as the fridge. Blaming the machine was 'an unacceptable excuse', said Kwong Wah Hospital chief of service and Public Doctors Association president Dr Yip Wai-chun. But Hospital Authority spokesman Dr Ko Wing-man said the guidelines simply demanded a temperature alarm in a 'proved blood refrigerator'. Dr Yip said: 'Looking at our fridges, I cannot understand how the Red Cross got itself into this situation. 'The chances of problems are minimal [at Kwong Wah]. 'I find it quite amazing, unless it's sabotage,' he said. Blood Transfusion Service hospital chief of service Dr Lin Che-kit said on Tuesday the police had ruled out sabotage. During the night of February 5, a fuse leading to two fridges at the Red Cross headquarters was tripped, cutting the power to both the fridges and the temperature alarm. A computer alarm also failed to sound. Dr Yip said temperature alarms on Kwong Wah machines had emergency power supplies and staff members checked the temperature every two hours. 'A 24-hour temperature chart means we can see immediately if there have been fluctuations of temperature in the fridge. 'For medicine we can't afford to have errors. They can blame the machine but we are in control of the machines. 'I think they should really think about whether there are problems of policy or procedures,' he said. Dr Lin admitted on Tuesday that 'one fault - if there is one - might be relying too much on machines and not enough on manual checking'. Queen Mary Hospital senior clinical pathologist Gregory Cheng Yin-ming, who is in charge of the blood bank, said the hospital was changing some of its fridges to an independent alarm system. The new system would work irrespective of the power supply to the fridge. 'I think it's better,' he said. The fridges which had an integral alarm were used almost hourly in the main blood bank, which operated 24 hours, he said. The Blood Transfusion Service does not operate round the clock.