Shock

When SHOCK occurs, generally there is an inadequate delivery of nutrients to critical tissues and organs, and also an inadequate removal of cellular waste products from the tissues. The cause of this inadequacy can be of cardio- / hypovolemic- / neurogenic- / anaphylactic-/ septic origin, however ultimately, lead to the deterioration of different body parts.

In the case of cell hypoxia, the non-progressive phase of shock then kicks in, in which our body’s negative feedback mechanisms attempt to return normal cardiac output and arterial pressure i.e. to recover from shock, by, namely, baroreceptors, renin-angiotensin system etc. However, when failing to recover from shock, shock proceeds to the progressive phase. The cause of shock and its resulting effects on, say, low systemic filling pressure, or reduced venous return etc., become a vicious circle that eventually leads to an irreversible deterioration of circulation and, to death.

Cadiogenic shock
i.e. body suffers from lack of nutrition and deteriorates due to inadequate cardiac pumping, in which, 1) often occurs after acute heart attacks or prolonged periods of slow progressive cardiac deterioration; 2) caused by a decreased venous return
- problem can be compounded by a low arterial pressure e.g. in circulatory shock, which reduces the coronary blood supply even more
- the condition thus becomes a vicious circle i.e. shock causes more shock
∴elevate arterial pressure!!! By infusion of whole blood / plasma, or blood-pressure raising drug

Hypovolemic shock
i.e. diminished blood volume caused by, most commonly, haemorrhage, which then decreases the filling pressure of the circulation and, as a consequence, decreases venous return; as the result, cardiac output falls, and shock comes after.

Neurogenic shock
When there is massive dilation of veins, mean systemic filling pressure decreases; thus, filling the circulatory system adequately had become incapable even with a normal amount of blood. Venous pooling of blood reduces cardiac output, therefore limits the gaseous and nutrition exchange around the body.

Anaphylactic shock
In anaphylaxis, basophils and mast cells release histamine, which causes dilation of veins and arterioles, as well as an increased permeability in capillaries. The effect of these is a great reduction in venous return, and shock.

Septic shock
A septic shock occurs when a blood-borne bacterial infection widely spread around the body, causing extensive damage. Signs of circulatory collapse often include marked vasodilation in patients with septic shock, while high fever from the infection is a possible cause. As the infection becomes more severe, the circulatory system deteriorates at the same time, and shock becomes more progressive.

Reference: Guyton