Pathophysiology of Asphyxia
(a) With asphyxia there will be hypoxia/ anoxia and hypercarbia.
- The hypercarbia will cause increased secretion of fibrinolysin by the vascular endothelium.
The fibrinolysin will cause:
(i) increased fluidity of blood
(ii) neck veins and right heart distended with blood
(iii) increased hypostatic blood
- The blood will contain increased levels of reduced haemoglobin and this accounts for bluish discoloration (cyanosis) seen both externally and internally. The hypostatic areas will be show deep blue discoloration soon after death.
(b) The anoxia will cause capillary dilatation resulting in increased blood in the tissues. This results in congestion.
(c) The anoxia also caused increase in the capillary permeability resulting in transudation of plasma from the vessels to the tissues. This results in the tissue oedema.
(d) The loss of fluid also causes haemoconcentration which in turn retards the blood flow and stasis. This results in a rise in the intra-capillary pressure leading to rupture. This results in the petechial haemorrhages.
(e) Anoxia also causes disruption of the capillary endothelium which also contribute to the petechial haemorrhages
(f) With anoxia there will be dysfunction of organs / tissues / cells / according to their degree of specialization and cessation of activity of cells / tissues / organs one by one resulting in death.