 2. Two or more criteria for the systemic inflammatory response syndrome SIRS: i heart rate greater than 90 beats per minute; ii respiratory rate greater than 20 breathes per minute, or a PaC02 less than 32 mm Hg, or mechanically ventilated; iii temperature greater than 38 or less than 36 degrees Celsius; iv or a white blood cell count greater than 12,000 x 109L or less than 4,000 x 109L, or more than 10 bands on the differential. 