Mosby's Chapter 2 - Blood Studies Flashcards
Why do we obtain blood studies?
1) to establish a diagnosis
2) to rule out a clinical problem
3) to monitor therapy
4) to establish a prognosis
5) to screen for disease
6) to determine effective drug dosage and to prevent toxicity
What are the three general methods for blood collection?
Venous
Arterial
Skin Puncture
What are the characteristics of Arterial blood?
oxygenated
Uniform in composition throughout the body
What are the characteristics of venous blood?
deoxygenated
Not uniform throughout the body
What is the blood from a skin puncture?
a mixture of arterial and venous blood
and
intracellular and interstitial fluid
What is the primary source of blood collection?
Venous puncture
Which veins are the common sites of venous puncture?
Basilic
Cephalic
Median Cubital
Sometimes femoral
What is the order of tubes filled?
1) blood culture tubes
2) Nonadditive tubes (red)
3) Coagulation tubes (blue)
4) Heparin tubes (green)
5) EDTA-K3 tubes (lavendar)
6) Oxalate-fluoride tubes (gray)
What angle should the needle be at for a venous puncture?
15 degrees to skin
What are potential complications of venous puncture?
Bleeding
Hematoma
Infection
Dizziness and Fainting
Which arm should you use to collect venous blood from?
Those without an IV or dialysis arteriovenous fistula
What is arterial blood used to measure?
Oxygen
CO2
pH
= Arterial Blood Gases (ABGs)
Which arteries are used for arterial puncture?
Brachial and Radial
What should be performed before an arterial puncture?
the Allen test
What is a positive Allen test?
Flushing is observed immediately in the hand after releasing pressure on the ulnar artery
Why is the allen test important?
It ensures collateral circulation to the hand if thrombosis of the radial artery occurs during puncture
What angle should the needle be at for arterial puncture?
45-60 degrees to the skin
How long should you apply pressure to the site after arterial puncture?
3-5 minutes or longer if they are on anticoags
What are potential complications of Arterial Puncture?
Arterial Thrombosis
Hematoma Formation
Bleeding
What is a skin puncture also known as?
capillary puncture
Who are skin punctures most commonly performed on?
pediatric patients
What are the common sites of skin puncture?
Fingertips
Earlobes
Heel
What is the most common site of skin puncture in infants?
Heel
What are potential complications of skin punctures?
Infection
Hematoma
Bleeding
When should a lipoprotein draw be performed?
12-14 hours after fasting
How long should the patient be fasting for in order to obtain a fasting blood glucose test?
8 hours
When should specimens be tested after collection?
1 hour
What are the criteria for rejection of a sample?
1) Improper sample ID
2) Wrong collection tube used
3) Insufficient Blood Quantitiy
4) Hemolyzed Blood Sample
5) Improper transport of sample
6) Insufficient filling of anticoagulated blood
Who is Alanine Aminotransferases commonly higher in?
Elderly
Men and African Americans
Infants
What does the alanine aminotransferase represent?
Identifies hepatocellular diseases of the liver
Injury or disease affecting the liver, heart, or skeletal muscles will cause a release of this enzyme into the bloodstream and an increased level
What is the DeRitis ratio?
ALT/AST
Is < 1 in hepatocellular diseases
> 1 in hepatitis
What are significantly increased levels of ALT associated with?
Hepatitis
Hepatic necrosis
Hepatic ischemia
What are moderately increased levels of ALT associated with?
Cirrhosis Cholestasis Hepatic tumor Hepatotoxic drugs Obstructive jaundice Severe burns Trauma to striated muscle
What are mildly increased levels of ALT associated with?
Myositis Pancreatitis MI Infectious mononucleosis Shock
What does Alkaline phosphatase indicate?
Used to detect and monitor disease of the liver or bone
In what environment is Alkaline phosphatase increased in?
Alkaline (pH 9-10)
What are also used to distinguish between liver and bone diseases with ALP?
Isoenzymes ALP1 and ALP2
What is ALP1?
Heat stable isoenzyme of ALP that is associated with the liver
What is ALP2?
Inactivated by heat and associated with bone
What is 5’-nucleotide season?
Enzyme found predominantly in liver
If ALP and this are high = liver disease
What is significant about increased ALP levels in children?
These increased levels are normal due to children’s bones constantly growing and are especially high during the growth spurt
What normal findings can also cause ALP to increase?
Ingestion of a meal
What diseases are indicated by increased levels of ALP?
Primary cirrhosis
Intrahepatic or extrahepatic biliary obstruction
Primary or metastatic liver tumor
Metastatic tumor to the bone Healing fracture Hyperparathyroidism Osteomalacia Paget disease Rheumatoid arthritis Rickets Intestinal ischemia or infarction Sarcoidosis
What disease are indicated by decreased levels of ALP?
Hypophosphatemia Hypophophatasia Malnutrition Milk-alkali syndrome Pernicious anemia Scurvy
What does the amylase indicate?
Used to detect and monitor the clinical course of pancreatitis
Often ordered when a patient presents with acute abdominal pain
When would values of amylase be normally slightly increased?
During pregnancy and in older adults
What can cause a false negative report of amylase?
IV dextrose
What cells are amylase found in?
Pancreatic Acinar cells
What diseases are associated with increased levels of amylase?
Acute pancreatitis Chronic relapsing pancreatitis Penetrating peptic ulcer into the pancreas GI disease Acute cholecystitis Parotiditis (mumps) Ruptured ectopic pregnancy Renal failure Diabetic ketoacidosis Pulmonary infarction After endoscopic retrograde pancreatography
What does the anion gap indicate?
Calculation is used to evaluate patients with acid-base disorders
Attempts to identify the potential cause of the disorder and can also be used to monitor therapy for acid-base abnormalities
What is the anion gap?
Difference between the cations and anions in the extra-cellular space that are routinely calculated in the lab
(Sodium + potassium) - (Chloride + Bicarbonate)
What is the bicarbonate in the anion gap actually a measurement of?
Venous CO2, not arterial bicarbonate
What diseases does does an increased anion gap occur in?
Lactic acidosis Diabetic ketoacidosis Alcoholic ketoacidosis Alcohol intoxication Starvation Renal failure Increased GI losses of bicarbonate (diarrhea or fistula) Hypoaldosteronism
What diseases do decreased anion gaps indicate?
Excess alkali ingestion Multiple myeloma Chronic vomiting or gastric suction Hyperaldosteronism Lithium toxicity
What does the arterial blood gases test for?
PH PCO2 HCO3- PO2 O2 saturation O2 content Base/Excess
What is the indication for arterial blood gases?
Provides valuable information in assessing and managing a patients respiratory and metabolic acid-base and electrolyte homeostasis
Also used to assess the adequacy of oxygenation
What is the mode of compensation for Respiratory acidosis?
Kidneys will retain increased amounts of HCO3- to increase pH
What is the mode of compensation for respiratory alkalosis?
Kidneys will excrete increased amounts of HCO3- to lower pH
What is the mode of compensation for metabolic acidosis?
Lungs “blow off” CO2 to raise pH
What is the mode of compensation of metabolic alkalosis?
Lungs retain CO2 to lower pH
What are arterial blood gases contraindicated in?
If there is no palpable pulse
Cellulitis or open infection is present in the area being considered for access
The Allen test is negative which indicates there is no ulnar artery and there is risk of using the radial artery
There is an AV fistula proximal to the site or proposed access
Patient has severe coagulopathy
What test must be performed before collecting an arterial blood gas?
Allen test
What is the indication for aspartame aminotransferase (AST)?
Evaluates patients with suspected hepatocellular diseases
What may cause normal increased levels of AST?
Exercise
What may cause normal decreased levels of AST?
Pregnancy
Where is AST found?
In highly metabolic tissues like the heart, liver, skeletal muscle cells
Also found in kidneys, pancreas, and RBCs
What diseases indicate increased levels of AST?
Hepatitis Hepatic cirrhosis Drug-induced liver injury Hepatic metastasis Hepatic necrosis Hepatic surgery Infectious mononucleosis with hepatitis Hepatic infiltration process Skeletal muscle trauma Recent noncardiac surgery Multiple traumas Severe, deep burns Progressive MD Recent convulsions Heat stroke Primary muscle disease Acute hemolytic anemia Acute pancreatitis
What diseases are indicated in decreased levels of AST?
Acute renal disease Beriberi Diabetic ketoacidosis Pregnancy Chronic renal dialysis
What is bilirubin indicated for?
Evaluates liver function
In adult patients it evaluates for hemolytic anemia and in infants for jaundice
What is delta bilirubin?
Form of bilirubin bound to albumin
Total bilirubin - (direct bilirubin + indirect bilirubin)
What diseases are associated with increased blood levels of conjugated bilirubin?
Gallstones Extrahepatic duct obstruction Extensive liver metastasis Cholecstasis from drugs Dubin-Johnson syndrome Rotor syndrome
What diseases are associated with increased blood levels of unconjugated bilirubin?
Erythroblastosis fetalis Transfusion reaction Sickle cell anemia Hemolytic jaundice Hemolytic anemia Pernicious anemia Large-volume blood transfusion Resolution of large hematoma Hepatitis Cirrhosis Sepsis Neonatal hyperbilirubinemia Critter-Najjar syndrome Gilbert syndrome
What disease are associated with increased urine levels of bilirubin?
Gallstones Extrahepatic duct obstruction Extensive liver metastasis Cholecstasis from drugs Dubin-Johnson syndrome Rotor syndrome
What blood type is considered a universal donor?
O
What blood type is considered a universal recipient?
AB
What is O blood type?
No A or B antigens
Yes anti-A and anti-B antibodies