Welch Allyn Connectivity Server - Programmers guide - Manual (Page 27)

Programmer’s Guide WACS outbound HL7 protocols 23
Vital-sign numerics filters
One of the following vital-sign numerics filters must be configured for the WACS server:
Table 14. WACS vital-sign filters
Filter Function
Median For an odd number of sample points, WACS sorts the data in descending order and returns the middle
(median) data point. For example, for the values 56, 72, 96, 82 and 78, the returned value is 78.
For an even number of sample points, WACS returns either the average (mean) or one of the two
middle points. For example, for the values 56, 72, 70, 96, 82 and 78, the returned value is either the
mean value (76) or one of the middle values (72 or 78).
Closest Returns the data closest to the given reference point.
Example: Heart rate values are calculated every minute over a period of five minutes. For example,
heart rate values of 56, 72, 96, 82, and 78 are collected, and then the HL7 message is constructed at
the five-minute reference point. The HL7 message is contains only the heart rate value of 78, which is
the value closest to the reference point.