PE Exam Two (Part 4)

Carboxyhemoglobin (COHb)

Formed when carbon monoxide (CO) binds with hemoglobin.

CO vs. Oxygen Affinity

CO has an affinity 210x that of oxygen for hemoglobin.

COHb Levels in Smokers

5 to 7%

Methemoglobin Formation

Occurs from chemical ingestion or when O2 cannot combine with hemoglobin.

Methemoglobinemia Presentation

Looks like high oxygen saturation, low PaO2.

Nitric Oxide (NO) & Methemoglobinemia

Nitric oxide does not work well with this condition.

Methemoglobinemia Treatment

Methylene blue helps.

Sulfhemoglobinemia Causes

Formed when sulfur binds with Hb; can be triggered by medications like Imetrex for migraines.

Sulfhemoglobinemia Symptoms

Includes a blueish or greenish discoloration of the blood, skin, and mucous membranes.

Polycythemia

-Characterized by an increase in RBC count, Hb, and HcT.

-Secondary polycythemia is the most common.

Secondary Polycythemia

most common; associated with chronic hypoxemia in COPD & heavy smokers)

Polycythemia Mechanism

-CO binds with Hb =

-O2 carrying capacity reduced= Hypoxemia/Hypoxia = Stimulates kidney to produce erythropoietin =

-Bone marrow produces RBC

Reticulocyte

-Normal 1% of total RBC's

-Helpful in evaluating anemias

-Newborns have slightly higher values

Reticulocyte Immature RBC's

Immature RBC's indicate extreme stress on bone marrow to produce RBC's

Hemostasis

keeps blood function normal & ability to prevent hemorrhage.

Hemostasis clot time

Plasma to form a fibrin clot should be < 1 minute

Hemostasis Assessment Tests

Platelet count, APTT, and PT/INR, which should be checked before obtaining an ABG.

Platelet Count

Important for blood clot formation; natural source of growth factors involved in hemostasis.

Platelets

Circulate in the blood of mammals and are involved in hemostasis, leading to the formation of blood clots

Thrombocytopenia vs Thrombocytosis

Thrombocytopenia means low platelets, and thrombocytosis means high platelets.

Prothrombin Time (PT)

Evaluates time it takes extrinsic blood factors to form a clot as a defense against hemorrhage.

Normal Prothrombin Time (PT)

12-15 seconds.

Causes of Prolonged PT

-vitamin K deficiency

-hormone drugs

DIC (disseminated intravascular coagulation)

-liver disease

-warfarin use.

APTT

-Used to monitor heparin IV

-Initial test if bleeding problems are suspected.

APTT Time

Excessive bleeding or bruising 30-40 seconds clotting time

Electrolytes

-Free ions in body fluids and allow this fluid to conduct an electrical current.

-important when managing pt with fluid balance problems.

Sodium (Na+)

Major cation (+) of extracellular fluid

Normal Sodium Level

135 - 145 mmol/L

Sodium Regulation

Renal regulation, influenced by hormones

Adrenal Gland & Aldosterone

Involved in normal sodium loss

Insensible Sodium Fluid Loss

Normal 12 mL/kg

Sweat and Urine Sodium Fluid Loss

Sweat is variable; urine normal is 300-1500 mL/day

Hypothalamus

Produces antidiuretic hormone (ADH)

Hypernatremia (Na+) Level

> 147 mEq/L

Hypernatremia Causes

-Loss of water without loss of salt (profuse sweating, diarrhea, renal diseases, prolonged hyperpnea)

-Insufficient water intake

-Hormonal abnormalities.

Hypernatremia (Na+) Clinical Manifestation

Excessive thirst & dry, sticky mouth.

Hyponatremia Level (Na+)

< 137 mEq/L

Hyponatremia Causes

Excess sodium loss compared to water loss (diuretic therapy, diarrhea, nephrosis).

Severe Hyponatremia (Na+)

< 115 mEq/L (confusion, abnormal sensorium, muscle twitching, seizures).

Potassium (K+) Location

Major cation of intracellular fluid.

Normal Potassium (K+) Level

3.5 - 5.0 mEq/L (serum concentration).

Potassium (K+) Function & Acid-Base Balance

Normal K+ levels are necessary for adequate muscle contraction. Changes in K+ concentration are related to acid base balance.