wherein the second control unit increases the effect of the inflow liquid pump and the outflow device to rinse the surgical site so that flow of the inflow irrigation liquid is increased when the amount of debris is increased in the irrigation liquid in, or coming out of, the surgical site or the inflow liquid pump is regulated so that {HEAD ~ pressure} of the irrigation liquid is increased when {TAIL ~ the amount} of blood cells, red blood cells or haemoglobin is increased in the irrigation liquid in, or coming out of, the surgical site 
wherein the second control unit increases the effect of the inflow liquid pump and the outflow device to rinse the surgical site so that flow of the inflow irrigation liquid is increased when the amount of debris is increased in the irrigation liquid in , or coming out of , the surgical site or the inflow liquid pump is regulated so that { HEAD ~ pressure } of the irrigation liquid is increased when { TAIL ~ the amount } of blood cells , red blood cells or haemoglobin is increased in the irrigation liquid in , or coming out of , the surgical site
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