A Panic Delta is a type of attribute used to alert RippleDown that a test value is abnormal in some respect.

The alert is generated if the current value is outside some defined range, or alternatively, if the value has increased or decreased from its previous value by an amount greater than what is allowed.

A Panic Delta will give a value of “true” if the alert has been triggered for the current case. If the Panic Delta is not triggered for the case, it simply will not show.

Once defined, the normal way to use a Panic Delta is to build a rule that gives an Internal comment if that Panic Delta triggers for the case. In this way, the case will not be autovalidated, but will be sent to the Validator for review.

To see in the Validator why a Panic Delta has triggered, select the “true” value of the Panic Delta in the case, and use the right-click popup “Display sample value”.

In summary, Panic Delta processing will take one of two paths:

  1. If there is just one episode in the case, or more than one episode but the previous episode is too long ago, then the Panic Delta will trigger if the test value is outside a reference range.
  2. Alternatively, if there are 2 or more episodes and the previous episode is recent, then the Panic Delta will trigger if the current test value is outside a panic range, or else, if it has increased or decreased more than an allowable amount (or percentage) from the previous episode.

The definition of “recent” is in terms of a number of days that you can specify. In more detail, to define a Panic Delta:

  • Start the Attribute Manager and select the test (i.e. attribute) that the Panic Delta should refer to.
  • Using the menu (or right-click popup, or tool bar), select “Add delta”.
  • Enter a name for the Panic Delta, and then [OK].
  • The main Panic Delta screen will then show, consisting initially of just 1 row.
  • Edit the elements in the row using the right-click menus.

Each row of the Panic Delta contains the following:

  • Constraints
    • These are criteria that must be satisfied for the panic delta processing to continue. Examples are, age > 50, sex is “F”.
    • Up to 2 constraints can be defined per row.
    • To edit or add a constraint, select a constraint cell and use the right-click menu “Edit Constraint”.
    • The constraints will normally refer to other attributes of the case, like age or sex, rather than the test attribute itself. Note that the constraints can refer to derived attributes such as list attributes, numeric ranges or calculated values.
    • All other ranges in the Panic Delta refer to the test attribute.
    • If you leave a constraint empty, then it is assumed to be satisfied.
    • If both constraints are satisfied by the current case, then the panic delta processing will continue, looking next at the Reference Range.
  • Reference range
    • The Panic Delta reference range is something you define for the test attribute – it may or may not correspond to the reference range supplied by the Laboratory Information System as part of the case.
    • If there is only 1 episode in the case, then the panic delta will trigger if the attribute is outside the reference range.
    • You should not leave the reference range blank, otherwise all single episode cases will trigger the panic delta.
    • To edit or add a reference range, select the reference range cell and use the right-click menu “Edit reference range”
    • If there are 2 or more episodes in the case, and they are sufficiently close in time, then the reference range is ignored and the panic / action range is used.
  • Panic / Action range
    • Used if there are 2 or more episodes in the case, and the time between the current test value and the previous test value is less than the specified number of days, then the panic delta will trigger if the attribute is outside the panic / action range.
    • This enables you to define a wider panic / action range than reference range, for those situations where you are closely monitoring the trend of a test value.
    • To edit or add a panic / action range, select the panic / action cell and use the right-click menu “Edit panic/action range”
    • If the test value is within the panic / action range (and we have the situation of the 2 episodes close in time), then the variation range and allowable delta processing is done.
  • Delta Check (variation range, allowable increase, allowable decrease, units, days)
    • A variation range defines the range of test values for which the allowable increase or decrease is checked.
    • This allows you to define different allowable increases or decreases depending on the absolute value of the test attribute.
    • To edit any of the delta check fields, select a delta check cell and use the right-click menu “Edit delta check fields”
    • By default, each allowable increase or decrease will be interpreted as being in absolute units . However, you can change this to percentage.
    • To add several variation ranges, each with a different allowable increase or decrease, use the right-click menu “Copy this row”, then change just the delta check fields for the new row.

Multiple rows can be defined if you require different reference ranges, panic / action ranges, or delta checks for different constraints, e.g. a new set of ranges if the patient is female, or over a certain age. To do this, use the right-click menu “Add a row”, then edit the constraints and ranges for the new row.

Rows in the Panic Delta can be re-ordered using the right-click menus “Move up”, “Move down”. They can also be removed if required.

When you have finished defining the Panic Delta, click the [Close] button. The new Panic Delta will appear as an attribute in all cases (including cornerstone cases) where it triggers.