The invention enables achievement of control over the pressure in, and flow through, the surgical site, the detection of blood cells, red blood cells, haemoglobin and debris from the surgical site, the detection of blood lost from the surgical site, and control of the flow and pressure through the surgical site by use of signals from {HEAD ~ detectors} detecting blood cells, red blood cells, {TAIL ~ haemoglobin} and debris from the surgical site 
detecting
The invention enables achievement of control over the pressure in , and flow through , the surgical site , the detection of blood cells , red blood cells , haemoglobin and debris from the surgical site , the detection of blood lost from the surgical site , and control of the flow and pressure through the surgical site by use of signals from { HEAD ~ detectors } detecting blood cells , red blood cells , { TAIL ~ haemoglobin } and debris from the surgical site
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