Almost one in four pieces of hospital medical equipment that could be paralysed by the millennium bug is potentially life-saving, it was revealed yesterday. The Hospital Authority needs to spend $258 million to make equipment used in vital surgery bug-proof, a paper to be discussed by its planning committee today reveals. A study by the authority and government experts shows about 18,000 of the 80,000 pieces of equipment performed potentially life-saving functions. Among the equipment which the bug could paralyse were a physiological monitoring system and an electrocardiograph which have built-in microprocessors, it said. The authority has classified the risk level for equipment into four categories - Level I (fatal) is life threatening, causing immediate and direct harm to a patient, while Level II (critical) is potentially life-threatening, producing incorrect results which could lead to a wrong treatment decision. The others are Level III (marginal) and Level IV (no impact). All equipment falling into the Level I category is scheduled to be dealt with by the first quarter of next year, and Level II by the end of next year. Contingency plans will be drawn up for unforeseen and uncontrollable events that will affect the authority's core functions during the Y2K roll-over - exactly 500 days from yesterday. The authority has been criticised for delayed action in tackling the problem, raising fears critical services will be compromised. But it has put the blame on the lack of information globally and poor response to requests for help from equipment sellers.