Index: firmware/App/Modes/Dialysis.c
===================================================================
diff -u -r43d1739837a207e6d4d2960f3f0442af85b22a8c -r75e1ae332d1446dddf9b8d4ce6e8317449c57d67
--- firmware/App/Modes/Dialysis.c	(.../Dialysis.c)	(revision 43d1739837a207e6d4d2960f3f0442af85b22a8c)
+++ firmware/App/Modes/Dialysis.c	(.../Dialysis.c)	(revision 75e1ae332d1446dddf9b8d4ce6e8317449c57d67)
@@ -7,8 +7,8 @@
 *
 * @file    Dialysis.c
 *
-* @author  (last)      Dara Navaei
-* @date    (last)      01-Dec-2022
+* @author  (last)      Michael Garthwaite
+* @date    (last)      19-Jan-2023
 *
 * @author  (original)  Sean
 * @date    (original)  15-Jan-2020
@@ -620,6 +620,8 @@
  *************************************************************************/
 void execDialysis( void )
 {
+    DIALYSIS_STATE_T priorSubState = currentDialysisState;
+
     // Check ultrafiltration max rate and accuracy during dialysis (even when ultrafiltration is paused).
     checkUFAccuracyAndVolume();
 
@@ -642,6 +644,10 @@
     // Calculate UF measured volume and provide to dialysate outlet pump controller (watch UF regardless of dialysis state)
     updateUFVolumes();
 
+    if ( priorSubState != currentDialysisState )
+    {
+        SEND_EVENT_WITH_2_U32_DATA( HD_EVENT_SUB_STATE_CHANGE, priorSubState, currentDialysisState );
+    }
     // Publish saline bolus data at set interval (whether we are delivering one or not)
     publishSalineBolusData();
 }
@@ -657,6 +663,7 @@
 static DIALYSIS_STATE_T handleDialysisUltrafiltrationState( void )
 {
     DIALYSIS_STATE_T result = DIALYSIS_UF_STATE;
+    UF_STATE_T priorSubState = currentUFState;
     U32 preStop = getTreatmentParameterU32( TREATMENT_PARAM_HEPARIN_PRE_STOP_TIME );
     F32 minRem  = (F32)getTreatmentTimeRemainingSecs() / (F32)SEC_PER_MIN;
 
@@ -684,6 +691,11 @@
             break;
     }
 
+    if ( priorSubState != currentUFState )
+    {
+        SEND_EVENT_WITH_2_U32_DATA( HD_EVENT_SUB_STATE_CHANGE, priorSubState, currentUFState );
+    }
+
     return result;
 }
 
@@ -699,6 +711,8 @@
 {
     DIALYSIS_STATE_T result = DIALYSIS_SALINE_BOLUS_STATE;
 
+    SALINE_BOLUS_STATE_T priorSubState = currentSalineBolusState;
+
     switch ( currentSalineBolusState )
     {
         case SALINE_BOLUS_STATE_IDLE:
@@ -723,6 +737,11 @@
             break;
     }
 
+    if ( priorSubState != currentSalineBolusState )
+    {
+        SEND_EVENT_WITH_2_U32_DATA( HD_EVENT_SUB_STATE_CHANGE, priorSubState, currentSalineBolusState );
+    }
+
     return result;
 }