What will happen if no diffusion for 1 hour during dialysis ,is harmful to patient?

Do you mean ultrafiltration or removing of fluid for one hr?

To put it simply, the patient did not have his blood cleaned for the first hour. Instead he or she was only getting fluid removed, therefore did not receive adequate removal of waste. It is essentially the same as shortening their time by an hour. They could experience increased symptoms of itchiness, difficulty sleeping, loss of appetite, tiredness. This happened in a clinic I worked in- we kept the pt an extra hour with the UF off.