Index: firmware/App/Controllers/PresOccl.c
===================================================================
diff -u -r487d3524cbf3b50dad1308fc1f68b733cc00c4cd -r727f30438c094ec62abe1fad1f5a8962cd304a4d
--- firmware/App/Controllers/PresOccl.c	(.../PresOccl.c)	(revision 487d3524cbf3b50dad1308fc1f68b733cc00c4cd)
+++ firmware/App/Controllers/PresOccl.c	(.../PresOccl.c)	(revision 727f30438c094ec62abe1fad1f5a8962cd304a4d)
@@ -152,6 +152,8 @@
 static OVERRIDE_F32_T venousPressure = {0.0, 0.0, 0.0, 0 };                     ///< Measured venous pressure.
 static OVERRIDE_U32_T bloodPumpOcclusion = {0, 0, 0, 0 };                       ///< Measured blood pump occlusion pressure.
 static PRESSURE_LIMITS_STATES_T currPresLimitsState;                            ///< Current pressure limits state.
+static F32 arterialPressureOffset;                                              ///< Arterial pressure sensor offset (in mmHg).
+static F32 venousPressureOffset;                                                ///< Venous pressure sensor offset (in mmHg).
 static S32 stableArterialPressure;                                              ///< Arterial pressure that limit window is based on (in mmHg).
 static S32 stableVenousPressure;                                                ///< Venous pressure that limit window is based on (in mmHg).
 static S32 currentArterialMaxLimit;                                             ///< Maximum arterial pressure limit (in mmHg).
@@ -242,6 +244,7 @@
     stableArterialPressure                   = 0;
     stableVenousPressure                     = 0;
     venLowPresExemptAfterAirTrapFillTimerCtr = 0;
+    resetArtVenPressureOffsets();
     longFilteredArterialPressure             = 0.0F;
     shortFilteredArterialPressure            = 0.0F;
     longFilteredVenousPressure               = 0.0F;
@@ -254,6 +257,34 @@
 
 /*********************************************************************//**
  * @brief
+ * The resetArtVenPressureOffsets function resets the arterial and venous
+ * offsets to zero.
+ * @details Inputs: none
+ * @details Outputs: arterialPressureOffset, venousPressureOffset
+ * @return none
+ *************************************************************************/
+void resetArtVenPressureOffsets( void )
+{
+    arterialPressureOffset = 0.0F;
+    venousPressureOffset   = 0.0F;
+}
+
+/*********************************************************************//**
+ * @brief
+ * The setArtVenPressureOffsets function sets the arterial and venous
+ * offsets to current readings.
+ * @details Inputs: none
+ * @details Outputs: arterialPressureOffset, venousPressureOffset
+ * @return none
+ *************************************************************************/
+void setArtVenPressureOffsets( void )
+{
+    arterialPressureOffset = getMeasuredArterialPressure();
+    venousPressureOffset   = getMeasuredVenousPressure();
+}
+
+/*********************************************************************//**
+ * @brief
  * The isCartridgeLoaded function determines whether a cartridge has been
  * properly loaded by looking at the BP occlusion pressure sensor.
  * @details Inputs: BP occlusion pressure
@@ -634,18 +665,23 @@
 
     if ( ARTERIAL_PRESSURE_NORMAL_OP == artPresStatus )
     {
+        F32 artPresPSI;
+
         // If the arterial pressure status is normal, convert the counts to pressure in mmHg
-        arterialPressure.data = ( (F32)( artPres - ARTERIAL_PRESSURE_OFFSET ) *
+        artPresPSI            = ( (F32)( artPres - ARTERIAL_PRESSURE_OFFSET ) *
                                   ( ARTERIAL_PRESSURE_MAX_PSI - ARTERIAL_PRESSURE_MIN_PSI ) / (F32)ARTERIAL_PRESSURE_SCALE ) + ARTERIAL_PRESSURE_MIN_PSI;
-        arterialPressure.data = arterialPressure.data * PSI_TO_MMHG;
+        artPresPSI            = artPresPSI * PSI_TO_MMHG;
+        arterialPressure.data = artPresPSI - arterialPressureOffset;
     }
 
     if ( VENOUS_PRESSURE_NORMAL_OP == venPresStatus )
     {
+        F32 venPresPSI;
+
         // Convert venous pressure to PSI and then mmHg
-        F32 venPresPSI = ( (F32)( venPres - VENOUS_PRESSURE_OFFSET ) * ( VENOUS_PRESSURE_MAX_PSI - VENOUS_PRESSURE_MIN_PSI ) / (F32)VENOUS_PRESSURE_SCALE ) +
-                           VENOUS_PRESSURE_MIN_PSI;
-        venousPressure.data = venPresPSI * PSI_TO_MMHG;
+        venPresPSI          = ( (F32)( venPres - VENOUS_PRESSURE_OFFSET ) * ( VENOUS_PRESSURE_MAX_PSI - VENOUS_PRESSURE_MIN_PSI ) / (F32)VENOUS_PRESSURE_SCALE ) + VENOUS_PRESSURE_MIN_PSI;
+        venPresPSI          = venPresPSI * PSI_TO_MMHG;
+        venousPressure.data = venPresPSI - venousPressureOffset;
     }
 
     // Filter inline pressure readings