Shock

Postoperative complications

Cardiovascular complications

1. systemic imbalances

2. cellular dysfunction

3. tissue perfusion inadequate

Shock

1. inadequate cellular metabolism & inadequate perfusion & oxygenation (can lead to death)

2. inadequate blood flow & inadequate oxygen results in inadequate oxygen & nutrients to cells,

cellular starvation, cell death, and eventually death

3. blood flow depends on pressure changes – greater to lesser pressure

4. mean pressure is highest in the aorta & lowest in the right atrium (to keep blood circulating)

Shock Results from three aspects of circulation

1. heart pump

2. peripheral resistance; resistance to passage of blood through small vessels (capillaries),

effective vascular & circulatory system with good tone (for vasoconstriction & dilation)

will constrict to ↑BP and dilate to ↓BP. With shock the sympathetic NS will constrict blood

3. blood volume: if pt hemorrhages, have↑risk for shock. The tissues are unable to extract &

use O₂ delivered. Body responds by sympathetic NS activation to constrict blood vessels.

Stroke volume = blood pumped out of aorta 60 ml is normal

Cardiac output = Stroke volume x heart rate (CO= SV x HR)

Mean arterial pressure (MAP) = CO x SVR. *you can use BP to figure out MAP which measures systemic vascular resistance

formula is: (Systolic + 2(Diastolic)) / 3 = MAP

example: for BP of 125/70 formula is (125 + 2(70)) / 3 = 88.33

Three Major types of shock

1. hypovolumic: ↓volume ( ↓intravascular volume)

2. cardiogenic: problem with heart's pumping ability

3. distributive: circulatory or vasoactive shock – alterations in vascular smooth muscle tone (problems

with peripheral resistance)

a. neurogenic: NS injury or reaction to drug (epidural) anesthetic

b. septic: infection

c. anaphylactic: hypersensitivity to drug

Shock involves:

1. hypoperfusion of tissues

2. hypermetabolism by cell

3. activation of inflammatory response to try to get back to homeostasis

Cellular Response – active transport, muscle contraction, & conduction of impulses makes cell more permeable

1. 1. ↓O₂ causes ↓ATP and ↑acid production

2. ↓ATP causes malfunction of Na⁺ and K⁺ pump (Na enters cell and K leaves)

3. ↑Na & water in cell causes cellular edema & further interferes with cell function

4. ↑cellular hypoxia causes ↑release of acid end product causes intracellular acidosis which causes lysosomal membranes to rupture and lytic enzymes to be released

5. lytic enzymes degrade protein, CHO, and fat; and cause death of cell

6. cellular death causes multiple substances to be released in blood stream

cellular response – con't (glucose primary substance used by ATP. glycogen stores depleted)

1. causes hyperglycemia an insulin resistance to mobilize for cellular metabolism

2. activates glycogenesis

3. glycogen stored in liver is converted to glucose through glycogenesis

4. increases the amount of glucose in the bloodstream

5. hyperglycemia

6. continued stress causes depletion of glycogen stores

7. resulting in increased proteolyis & cell death & organ failure