Worsening SOB while on dialysis

A 46yo female presented with worsening SOB over 2 weeks. She had decreased exercise tolerance and difficulty sleeping which was becoming progressively worse. No cough, chest pain or fevers. She had had a viral illness 3 weeks ago but had no residual Sx from this. 

PHx nightly peritoneal dialysis for the last 3 years post GN renal failure. This has been going well. nil issues, nil abdo pain. HT on usual meds, nil recent change. 

On Ex HR 100, sats 100% on air, BP 110/60, afebrile. She had fine crackles bibasally and normal HS, no calf swelling or peripheral oedema. Abdomen soft and NT.

This is her CXR

The CXR was interpreted as overloaded and the patient was referred to renal for fluid overload ? inadequate dialysis.

What ultrasound would you like to do at the bedside to clarify this?

What further investigations would you like to order?