Week 14: Shock

Anaerobic

Activity without Oxygen.

Arterial blood gases

Measures the level of oxygen and carbon dioxide in arterial blood. It's used to assess lung ventilation and to assess tissue oxygenation - how much oxygen oxygen cells in the body are receiving, as well as the pH status of the body.

Decompensate

Not being able to maintain the compensatory mechanisms of the body.

An example of a compensatory mechanism with hypovolemic shock - we're losing blood somewhere so the heart will beat faster and harder to get more oxygen out to the cells in the body. However, eventually, over time, the heart cannot sustain that and begins to decompensate.

Hypotension

A reduced blood pressure below normal range.

Multi-organ dysfunction syndrome (MODS)

The development of potentially reversible physiologic derangement involving two or more organ systems not involved in the disorder that resulted in ICU admission. It arises in the wake of a potentially life-threatening physiologic insult.

Perfusion

The passage of a fluid through a blood vessel of a specific organ or tissue, for example, say the kidneys or the liver. It's the process of delivering nutrients and oxygen from arterial blood into a capillary bed.

Systemic inflammatory response syndrome (SIRS)

Related to infections that have become severe and begin to spread throughout the body. Can occur because of ischemia, which is a decrease of blood flow to an area as well as infarction such as in the heart or the brain, or any kind of serious traumatic injury, such as with extensive burns or injuries.

The signs and symptoms include:

• Fever

• Edema

• Hypotension

• Tachycardia

• Tachypnea

• Impaired oxygenation

• Elevated leukocyte count

Third spacing

Shift of fluid into the interstitial space. And fluid leaves cells and leaves the vascular compartment and goes into the interstitial space. And then edema begins to develop and it's trapped in a 3D space.

Arterial blood gases

A group of tests used to measure the levels of oxygen and carbon dioxide in the blood, as well as the blood's pH and other parameters like bicarbonate levels. Blood must be taken from an artery. ABGs provide information about the respiratory and metabolic functions of the body.

Normal Values:

pH 7.35-7.45

PaCO2 35-45

HCO3 22-26

neurogenic shock

Also known as distributive or vasogenic shock. A type of shock caused by the sudden loss of the sympathetic nervous system signals to the blood vessels, leading to massive vasodilation and a drop in blood pressure.

It can result from spinal cord or head injuries, severe emotional stress, severely low blood glucose, and depressive action of some drugs, such as opioids.

Both anaphylactic shock and septic shock if left untreated can cause neurogenic shock.

Signs and symptoms that are different than other types of shock: dry, warm skin and bradycardia.

Septic shock

A severe systemic inflammatory response to a systemic infection throughout the body and the bloodstream. Severe sepsis is complicated by organ dysfunction (hepatic disease, renal failure etc.) as well and hypotension.

E coli, klebsiella pneumoniae and Pseudomonas are all bacterias that are known to cause severe vasodillation.

Risk factors for hypovolemic shock

• Burns

• Peritonitis - inflammation of the peritoneal cavity

• Dehydration

• Hemorrhage

• Excessive bleeding from cuts and other injuries, internal bleeding. For example, from the GI tract.

• Diarrhea

• Vomiting

• Excessive perspiration.

  The volume of blood loss to be considered hypovolemia is approximately 15 to 25%, which is approximately 750 to 1300 millilitres of blood.

Signs and Symptoms of shock

• blood pressure drop due to decrease blood volume or massive vasodillation

• heart rate - tachycardio initially as a compensatory mechanism then bradycardic when it can no longer sustain that.

• respiratory status - tachypeana as a compensatory mechanism

• neurologic status - initially anxious but LOC decreases as it progresses

• thirst - compsetaroy mechanism to try to increase fluids.

• Integumentary status - pale and cool and moist. due to peripheral vasoconstriction. The blood vessels of the skin begin to constrict to try and keep fluid in the body for essential organs

• Urinary output - initially a compensatory mechanism to try and retain fluid. Less oxygen going to kidney cells cause hypoxia and ischemia of the kidneys and will cause a decrease in urinary output further.

Antidiuretic hormone

Released by the pituitary in response to hypotension. Decreased blood pressure up against the artery walls stimulates the pituitary to release ADH which travels to the kidneys and tells them to retain fluid.

The electrical conduction system of the heart + shock

The cardiac center in the medulla stimulates the electrical conduction system of the heart (the SA node) to increase its impulses. This increases the heart rate which is a compensatory mechanism to try and increase oxygen perfusion to vital organs in the body.

The adrenal glands + Shock

• Release glucocorticoids, such as cortisol to stabilize the vascular system.

• Release aldosterone stimulates the kidneys to retain sodium and water and keep the fluid in to the body because fluid is lost with hypovolemic shock,

Anti-diuretic hormone + shock

A hormone that helps control water balance in the body by reducing the amount of water excreted by the kidneys, thus conserving water and preventing dehydration. It is made by the hypothalamus and is secreted into the blood by the pituitary. ADH acts on the kidneys during hypovolemic shock to help the body preserve water.

Rennin + shock

Causes peripheral vasoconstriction through the renin-angiotensin converting mechanism. It also causes aldosterone to be released from the adrenal glands as well.