Index: firmware/App/Controllers/PresOccl.c
===================================================================
diff -u -rd521a5bf7b77afeaf2b5593f8c287591cda3385c -r61e7d359d47a1f426153116e37f8fe5379c8b0f6
--- firmware/App/Controllers/PresOccl.c	(.../PresOccl.c)	(revision d521a5bf7b77afeaf2b5593f8c287591cda3385c)
+++ firmware/App/Controllers/PresOccl.c	(.../PresOccl.c)	(revision 61e7d359d47a1f426153116e37f8fe5379c8b0f6)
@@ -597,10 +597,18 @@
             {
                 SET_ALARM_WITH_2_F32_DATA( ALARM_ID_HD_VENOUS_PRESSURE_HIGH, venPres, venHighLimit );
             }
-            if ( TRUE == isPersistentAlarmTriggered( ALARM_ID_HD_VENOUS_PRESSURE_LOW, venPresLow ) )
+            // Cannot monitor for low venous pressure while venting air trap
+            if ( getValveAirTrapStatus() != STATE_OPEN )
             {
-                SET_ALARM_WITH_2_F32_DATA( ALARM_ID_HD_VENOUS_PRESSURE_LOW, venPres, venLowLimit );
+                if ( TRUE == isPersistentAlarmTriggered( ALARM_ID_HD_VENOUS_PRESSURE_LOW, venPresLow ) )
+                {
+                    SET_ALARM_WITH_2_F32_DATA( ALARM_ID_HD_VENOUS_PRESSURE_LOW, venPres, venLowLimit );
+                }
             }
+            else
+            {   // clear persistence if air trap valve is open
+                isPersistentAlarmTriggered( ALARM_ID_HD_VENOUS_PRESSURE_LOW, FALSE );
+            }
         }
         else
         {   // Reset persistence if alarm is out of scope