This has always been a very confusing concept even during my work in the PICU , why always in a case suffering from intra-cranial hemorrhage, it's always recommended that after intubation and mechanically ventilate the patient , you have to keep the patient in a hypocapneic state where pCO2 tension should be between 30 and 35 mmHg ?
when there's a hemorrhage , there's - obviously - an Increase in the intra-cranial pressure (simple physics, "inelastic" "tough"'non-compliant" meninges, so any intracranial mass would compress the soft brain tissue)
so when there is an increase in the intra-cranial pressure there would be a consequent Increase in the interstitial hydrostatic pressure that opposes the normal capillary hydrostatic pressure responsible to maintain the perfusion of the brain tissue ! leading to more brain hypoxia!
So , to override this issue decreasing pCO2 tension would induce cerebral vaso-constriction , though it -sounds terrifying to say- but yet this would help to maintain the capillary hydrostatic pressure high enough to overcome the mass effect hydrostatic pressure and maintain enough cerebral perfusion.
when there's a hemorrhage , there's - obviously - an Increase in the intra-cranial pressure (simple physics, "inelastic" "tough"'non-compliant" meninges, so any intracranial mass would compress the soft brain tissue)
so when there is an increase in the intra-cranial pressure there would be a consequent Increase in the interstitial hydrostatic pressure that opposes the normal capillary hydrostatic pressure responsible to maintain the perfusion of the brain tissue ! leading to more brain hypoxia!
So , to override this issue decreasing pCO2 tension would induce cerebral vaso-constriction , though it -sounds terrifying to say- but yet this would help to maintain the capillary hydrostatic pressure high enough to overcome the mass effect hydrostatic pressure and maintain enough cerebral perfusion.
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