Index: firmware/App/Modes/Prime.c
===================================================================
diff -u -rc68065fe2cfcfee46eae9d8a8af68b42b662661c -r130d76b56808975e8ba467a483bdb3a2e9899691
--- firmware/App/Modes/Prime.c	(.../Prime.c)	(revision c68065fe2cfcfee46eae9d8a8af68b42b662661c)
+++ firmware/App/Modes/Prime.c	(.../Prime.c)	(revision 130d76b56808975e8ba467a483bdb3a2e9899691)
@@ -62,8 +62,10 @@
 #define STEADY_VOLUME_COUNT_SEC                             ( 10000 / LOAD_CELL_STEADY_VOLUME_SAMPLING_TIME )  ///< Counter must be greater than 10 seconds before steady volume is true.
 #define STEADY_VOLUME_DIALYSATE_PRIME_TIME_LIMIT_MS         ( 90 * MS_PER_SECOND )                             ///< Time in msec for the reservoir volume to stabilize during dialysate prime state.
 #define STEADY_VOLUME_BYPASS_PRIME_TIME_LIMIT_MS            ( 62 * MS_PER_SECOND )                             ///< Time in msec for the reservoir volume to stabilize during bypass dialysate prime state.
-#define STEADY_VOLUME_DIALYSATE_PRIME_HISTERESIS_ML         ( 0.3F )                                           ///< mL of histeresis for the steady state check that determines when bypass line is primed.
-#define STEADY_VOLUME_BYPASS_PRIME_HISTERESIS_ML            ( 0.3F )                                           ///< mL of histeresis for the steady state check that determines when bypass line is primed.
+#define STEADY_VOLUME_DIALYSATE_PRIME_HISTERESIS_ML         0.3F                                               ///< mL of histeresis for the steady state check that determines when bypass line is primed.
+#define STEADY_VOLUME_BYPASS_PRIME_HISTERESIS_ML            0.3F                                               ///< mL of histeresis for the steady state check that determines when bypass line is primed.
+#define PRESSURE_OFFSET_DIALYSATE_PRIME_MMHG                50.0F                                              ///< +/- offset from start pressure that defines a range to keep PBo in during dialysate dialyzer prime state.
+#define DPO_RATE_STEP_PER_SEC_DIALYSATE_PRIME_ML_MIN        1                                                  ///< DPo rate step to maintain pressure during dialysate dialyzer prime state.
 
 #define VENOUS_PRESSURE_BUBBLE_CLEAR_MAX_MMHG               ( 200.0F )                                         ///< Maximum venous pressure reading (in mmHg) for bubble clear.
 #define BUBBLE_CLEAR_WAIT_TIME_INITIAL_MS                   ( 10 * MS_PER_SECOND )                             ///< Time in msec to wait for initial bubble clear pressure.
@@ -134,6 +136,8 @@
 static U32 primeSalineDialyzerStartTime;                        ///< Starting time of priming saline dialyzer circuit.
 static U32 primeSalineDialyzerBubbleClearStartTime;             ///< Starting time of priming saline dialyzer bubble clear.
 static U32 primeDialysateDialyzerStartTime;                     ///< Starting time of priming dialysate dialyzer circuit.
+static F32 primeDialysateDialyzerStartVenPres;                  ///< Starting venous pressure (mmHg) for dialysate dialyzer prime state.
+static U32 primeDialysateDialyzerDPoRate;                       ///< Record of last given DPo target rate for dialysate dialyzer prime state.
 static U32 primeDialysateBypassStartTime;                       ///< Starting time of priming dialysate bypass circuit.
 static U32 steadyVolumeSamplingStartTime;                       ///< Load cell steady volume sampling interval starting time.
 static F32 minimumReservoirVolume;                              ///< Minimum reservoir volume in mL.
@@ -731,13 +735,15 @@
             signalBloodPumpHardStop();
             setDialInPumpTargetFlowRate( DIALYSATE_PUMP_PRIME_FLOW_RATE_ML_MIN, MOTOR_DIR_FORWARD, PUMP_CONTROL_MODE_OPEN_LOOP );
             setDialOutPumpTargetRate( DPO_PUMP_PRIME_FLOW_RATE_ML_MIN, MOTOR_DIR_FORWARD, PUMP_CONTROL_MODE_OPEN_LOOP );
+            primeDialysateDialyzerDPoRate = DPO_PUMP_PRIME_FLOW_RATE_ML_MIN;
 
             // Calculate the time out value that must passed prior to checking for the steady state volume in the reservoir
-            primeDialysateDialyzerTimeLimit = (U32)( ( ( DIALYSATE_DIALYZER_TUBE_VOLUME_ML + dialyzerDialysateVolume ) * SEC_PER_MIN * MS_PER_SECOND ) / DIALYSATE_PUMP_PRIME_FLOW_RATE_ML_MIN );
-            minimumReservoirVolume = getLoadCellWeight( LOAD_CELL_RESERVOIR_1_PRIMARY );
-            steadyVolumeCount = 0;
-            steadyVolumeSamplingStartTime = getMSTimerCount();
-            primeDialysateDialyzerStartTime = getMSTimerCount();
+            primeDialysateDialyzerTimeLimit     = (U32)( ( ( DIALYSATE_DIALYZER_TUBE_VOLUME_ML + dialyzerDialysateVolume ) * SEC_PER_MIN * MS_PER_SECOND ) / DIALYSATE_PUMP_PRIME_FLOW_RATE_ML_MIN );
+            minimumReservoirVolume              = getLoadCellWeight( LOAD_CELL_RESERVOIR_1_PRIMARY );
+            steadyVolumeCount                   = 0;
+            steadyVolumeSamplingStartTime       = getMSTimerCount();
+            primeDialysateDialyzerStartTime     = getMSTimerCount();
+            primeDialysateDialyzerStartVenPres  = getFilteredVenousPressure();
 
 #ifndef _RELEASE_
             if ( SW_CONFIG_ENABLE_VALUE == getSoftwareConfigStatus( SW_CONFIG_DISABLE_PRIMING ) )
@@ -782,8 +788,21 @@
     {
         if ( TRUE == didTimeout( steadyVolumeSamplingStartTime, LOAD_CELL_STEADY_VOLUME_SAMPLING_TIME ) )
         {
-            F32 const currentReservoirVolume = getLoadCellWeight( LOAD_CELL_RESERVOIR_1_PRIMARY );
+            F32 currentReservoirVolume = getLoadCellWeight( LOAD_CELL_RESERVOIR_1_PRIMARY );
+            F32 venPres                = getFilteredVenousPressure();
 
+            // Adjust DPo speed to maintain venous pressure if necessary
+            if ( venPres > ( primeDialysateDialyzerStartVenPres + PRESSURE_OFFSET_DIALYSATE_PRIME_MMHG ) )
+            {
+                primeDialysateDialyzerDPoRate += DPO_RATE_STEP_PER_SEC_DIALYSATE_PRIME_ML_MIN;
+                setDialOutPumpTargetRate( primeDialysateDialyzerDPoRate, MOTOR_DIR_FORWARD, PUMP_CONTROL_MODE_OPEN_LOOP );
+            }
+            else if ( venPres < ( primeDialysateDialyzerStartVenPres - PRESSURE_OFFSET_DIALYSATE_PRIME_MMHG ) )
+            {
+                primeDialysateDialyzerDPoRate -= DPO_RATE_STEP_PER_SEC_DIALYSATE_PRIME_ML_MIN;
+                setDialOutPumpTargetRate( primeDialysateDialyzerDPoRate, MOTOR_DIR_FORWARD, PUMP_CONTROL_MODE_OPEN_LOOP );
+            }
+
             if ( currentReservoirVolume >= ( minimumReservoirVolume - STEADY_VOLUME_DIALYSATE_PRIME_HISTERESIS_ML ) )
             {
                 if ( ++steadyVolumeCount >= STEADY_VOLUME_COUNT_SEC )
@@ -1011,8 +1030,6 @@
     else if ( TRUE == doesAlarmStatusIndicateStop() )
     {
         setupForPrimePause();
-        state = HD_PRIME_PAUSE;
-        setCurrent4thLevelState( NO_SUB_STATE );
     }
 
     return state;