Index: firmware/App/Controllers/PresOccl.c
===================================================================
diff -u -r30f049651877229042e3f8700c8596e5b9a1e0f4 -r92f7cf45960398664518966bfaa2199f287cf2bd
--- firmware/App/Controllers/PresOccl.c	(.../PresOccl.c)	(revision 30f049651877229042e3f8700c8596e5b9a1e0f4)
+++ firmware/App/Controllers/PresOccl.c	(.../PresOccl.c)	(revision 92f7cf45960398664518966bfaa2199f287cf2bd)
@@ -56,6 +56,8 @@
 #define OCCLUSION_THRESHOLD                 25000                                           ///< Threshold above which an occlusion is detected.
 #define CARTRIDGE_LOADED_THRESHOLD          5000                                            ///< Threshold above which a cartridge is considered loaded.
 
+#define EMPTY_SALINE_BAG_THRESHOLD_MMGH     -200.0                                          ///< Threshold below which the saline bag is considered empty (in mmHg).  TODO - get real threshold from Systems
+
 #define PRES_ALARM_PERSISTENCE              ( 1 * MS_PER_SECOND )                           ///< Alarm persistence period for pressure alarms.
 
 /// Defined states for the pressure and occlusion monitor state machine.
@@ -151,6 +153,28 @@
     return result;
 }
 
+/*********************************************************************//**
+ * @brief
+ * The isSalineBagEmpty function determines whether the saline bag is empty.
+ * It is assumed that this function will only be called when pumping (BP) from
+ * the saline bag.  Determination is based on pressure going below a negative
+ * threshold.
+ * @details Inputs: arterial line pressure
+ * @details Outputs: none
+ * @return TRUE if arterial line pressure is below threshold, FALSE if not.
+ *************************************************************************/
+BOOL isSalineBagEmpty( void )
+{
+    BOOL result = FALSE;
+
+    if ( getMeasuredArterialPressure() < EMPTY_SALINE_BAG_THRESHOLD_MMGH )
+    {
+        result = TRUE;
+    }
+
+    return result;
+}
+
 /*********************************************************************//**
  * @brief
  * The execPresOccl function executes the pressure and occlusion monitor.