Lab Values and ICU Monitoring

A-aDo2: A-a gradient, norm 5-10 mmHg on .21, 30-60 on 100%,

>350mech support, <350 weaning. Represents potential to Oxygenate vs. the

amount of O2 in the artery. Every 50mmHg is approx. 2 percent shunt above norm of 2-5%

Increased A-a= SHUNT

A-a Gradient

a/A ratio: PaO2/PAO2 norm is 90%, >35%weaning, reflects efficiency of oxygenation as a percentage, <74% shunt, V/Q mismatch or diffusion defect

a/A ratio

Anion Gap= the difference in the measured cations and the measured anions in serum, plasma, or urine.

Used to assess Metabolic Acidosis or alkalosis, normal around 8-16 mEq/L. Use MUDPILES to determine cause of metabolic acidosis (high gap)

= ( [Na+] ) − ( [Cl−]+[HCO3−] ) without

potassium = ( [Na+]+[K+] ) − ( [Cl−]+[HCO3

−] ) with potassium

Anion Gap

CaO2: norm 20 vol% (Hbx1.34)SaO2 + (PaO2x.003) total amount

of O2 carried in 100ml of blood, combined content of O2 carried on Hb and dissolved in plasma,

(can be reduced by <Hb, anemia or <CO)

CaO2

CvO2: (Hb x 1.34)SvO2 + (PvO2 x .003) norm is 15 vol%, represents the value of O2

in blood returning to the right side of the heart after tissues have oxygenated.

C(a-v)O2 = arterial to mixed venous oxygen content difference

Determines how well the tissues take up O2

CvO2

VO2: O2 consumption, norm is 250mL/O2/L/min, [C(a-v)O2 x QT] x 10, the amount of O2

consumed by the body per liter of blood per minute.

Oxygen Consumption

DO2: O2 Delivery, (CaO2 x CO) x 10, norm is 1000mL/O2/min

The ability of oxygen to tissues based on cardiac output and Hb

DO2

No more than ½ the internal diameter of ETT or else improper entrainment.

French divided by 3.14 = size in mm. normal adult sizes 12 ‑ 14 fr

O.D. of catheter should not exceed 1/2 I.D.of airway

(1) to determine size of suction catheter for given ET tube: ETT size / 2 then x 3.14

(2) always round down – i.e. 7/2 x 3.14 = 10.99, use a 10 French

Suction Catheter to ET tube size

Cardiac Output (CO) = amt of blood ejected from the heart per minute

CO= Stroke Volume X heart ratenormal 4-8 L/min

QT = cardiac output

Cardiac Index (CI)= amount of blood pumps per minute based on body weight CI= CO/BSA, normal 2.4-4 L/min

Cardiac Output

QS/QT: Pulmonary Shunt equation (CcO2-CaO2)/(CcO2-CvO2) Norm 2-3%, >20% vent indication, <20% weaning, >30% is life threatening. Measures % of QT not exposed to ventilation, shunts

caused by atelectasis, edema, pneumonia, pneumothorax, obstructions

CcO2: Content of pulm capillary blood oxygen at 100% FIO2, (Hbx1.34)1 + (PAO2x.003) used in shunt equation

Shunt Equation

Order:◦ Creatine and BUN◦ Electrolytes◦ ABG◦ Vitals◦ Glucose Level◦ GRF◦ I/O◦ Specific gravity of urine◦ Albumin◦ Anion Gap◦ Renal ultrasound◦ CBC (Hb)

Renal Failure

A serum creatinine test measures the amount of creatinine in the blood and shows how well your kidneys are working. Creatinine is a breakdown product of creatine, which is formed when your body metabolizes food. Creatinine is taken out of your body by your kidneys and then passed out of your body in urine. Creatinine is produced in your body at a consistent rate, it is not affected by your diet or normal physical activities. If your kidneys are damaged, the level of creatinine in your blood increases.

Normal Results: .8 to 1.4 mg/dl

Creatine

BUN test is used to check kidney function. Urea nitrogen is what forms when protein breaks down. Urea is a waste product made when protein is broken down in your body. Urea is made in the liver and passed out of your body in the urine. Like creatinine, your BUN results can help your doctor determine how well your kidneys are working. For people with liver disease, the BUN level may be low even if the kidneys are normal. Kidney disease or blockage of the flow of urine from your kidney causes both BUN and creatinine levels to rise.

Normal Results: 7 to 20 mg/dl

BUN

A BUN-to-creatinine ratio can help your doctor check for problems, such as dehydration, that may cause abnormal BUN and creatinine levels. High BUN-to-creatinine ratios occur with sudden (acute) kidney failure, which may be caused by shock or severe dehydration. A low BUN-to-creatinine ratio may be associated with a diet low in protein, a severe muscle injury called rhabdomyolysis, pregnancy, cirrhosis or syndrome of inappropriate antidiuretic hormone secretion (SIADH).

Normal Results: 10:1 to 20:1

BUN:Creatinine ratio

AlbuminThe albumin test measures the amount of albumin in serum, the clear liquid portion of blood and determines if the liver is making enough albumin. This test helps in determining if a patient has liver disease or kidney disease, or if not enough protein is being absorbed by the body. Albumin is one of the two major proteins in the blood, the other is Globulin.  Albumin also helps carry some medicines and other substances through the blood and is important for tissue growth and healing.  Because albumin is made by the liver, decreased serum albumin may result from liver disease.  It can also result from kidney disease which allows albumin to escape into the urine.  Decreased albumin may also be explained by malnutrition or a low protein diet.

Normal Results: 3.4 to 5.4 g/dl

Albumin

This test measures the amount of Calcium in your blood, not the calcium in your bones. The body needs it to build and fix bones and teeth, help nerves work, make muscles contraction, help blood clot, and help the heart to work. The Calcium test screens for problems with the parathyroid glands or kidneys, certain types of cancers and bone problems, inflammation of the pancreas (pancreatitis), and kidney stones.

Normal Results: 8.5 to 10.2 mg/dl

Calcium

The serum chloride test measures the amount of chloride in the fluid portion of the blood. Chloride is a negatively charged molecule known as an electrolyte. It works with other electrolytes, such as potassium, salt (sodium), and carbon dioxide (CO2), to help keep the proper balance of body fluids and maintain the body's acid-base balance. Most of the chloride in your body comes from the salt (sodium chloride) you eat.

  Chloride levels can be used to help monitor high blood pressure,

heart failure and kidney disease.  High levels of chloride, known as hyperchloremia, typically indicate dehydration, metabolic acidosis and other conditions.  Decreased levels of chloride, known as hypochloremia, can indicate kidney disorder, Addison's disease, congestive heart failure and other conditions.

Normal Results: 96 to 106 mEq/L

Chloride

This test measures the amount of potassium in the blood. Potassium is both an electrolyte and a mineral. It helps keep the water (the amount of fluid inside and outside the body's cells) and electrolyte balance of the body. Potassium levels often change with sodium levels. When sodium levels go up, potassium levels go down, and when sodium levels go down, potassium levels go up.

Abnormal potassium levels may cause symptoms such as muscle cramps or weakness, nausea, diarrhea, frequent urination, dehydration, low blood pressure, confusion, irritability, paralysis, and changes in heart rhythm.

High blood potassium levels may be caused by damage or injury to the kidneys. This

prevents the kidneys from removing potassium from the blood normally. The most common cause of high potassium levels is kidney disease. Because potassium is important to heart function, patients should order this test if they have signs of high blood pressure or heart problems.

Low levels of potassium cause increased heart muscle activity, which can lead to an irregular heartbeat. Both high and low levels can lead to a heart attack in some cases.

Normal Results: 3.7 to 5.2 mEq/L

Potassium

A sodium test determines the level of sodium within the blood. Sodium is both an electrolyte and mineral. It helps maintain the water (the amount of fluid inside and outside the body's cells) and electrolyte balance of the body. Sodium is also important in how nerves and muscles work. A small percentage is lost through stool and sweat.

Normal Results: 135 to 145 mEq/L

For greater-than-normal sodium levels: High levels of sodium can increase the chance of high blood pressure. 

  If your total body water is low, high sodium levels may be due to fluid loss from excessive

sweating, diarrhea, use of diuretics or burns.  

If your total body water is normal, high sodium levels may be due diabetes insipidus or too little of the hormone vasopressin.  

If your total body water is high, high sodium levels may indicate hyperaldosteronism, Cushing syndrome, or a diet that's too high in salt or sodium bicarbonate.

For lower-than-normal sodium levels: Low total body water and sodium levels may be due to dehydration, vomiting, diarrhea, over diuresis, or ketonuria.

Sodium

Lactic acidosis is a physiological condition characterized by low pH in body tissues and blood accompanied by the buildup of lactate

Considered a distinct form of metabolic acidosis. The condition typically occurs when cells receive too little

oxygen For example during vigorous exercise. In this situation,

impaired cellular respiration leads to lower pH levels. Simultaneously, cells are forced to metabolize glucose anaerobically, which leads to lactate formation.

Therefore, elevated lactate is indicative of tissue hypoxia, hypoperfusion, and possible damage.

Lactic acidosis is characterized by lactate levels >5 mmol/L and serum pH <7.35.

Lactic Acidosis

Causes, incidence, and risk factors The most common cause of lactic acidosis is intense exercise.

However, it can also be caused by certain diseases, such as: AIDS Cancer Kidney failure Respiratory failure SepsisSymptoms Nausea Weakness Signs and tests Blood tests to check electrolyte levels Treatment The main treatment for lactic acidosis is to correct the

medical problem that causes the condition. Oxygen

Lactic Acidosis

Patients will require high levels of Oxygen, often requiring mechanical ventilation. They will also demonstrate with increase VA to compensate

Lactic Acidosis

The anion gap is the difference in the measured cations and the measured anions in serum, plasma, or urine.

The magnitude of this difference (i.e. "gap") in the serum is often calculated in medicine when attempting to identify the cause of metabolic acidosis. If the gap is greater than normal, then high anion gap metabolic acidosis is diagnosed.

Anion Gap

With potassium It is calculated by subtracting the serum

concentrations of chloride and bicarbonate (anions) from the concentrations of sodium and potassium (cations):

= [Na+] + [K+] − [Cl−] − [HCO3−]

Without potassium (Daily practice) However, the potassium is frequently ignored

because potassium concentrations, being very low, usually have little effect on the calculated gap. This leaves the following equation:

= [Na+] − [Cl−] − [HCO3−]

Anion Gap

In normal health there are more measurable cations compared to measurable anions in the serum; therefore, the anion gap is usually positive.

Because we know that plasma is electro-neutral we can conclude that the anion gap calculation represents the concentration of unmeasured anions.

The anion gap varies in response to changes in the concentrations of the above-mentioned serum components that contribute to the acid-base balance. Calculating the anion gap is clinically useful, as it helps in the differential diagnosis of a number of disease states.

Anion Gap

"Mudpiles" The mnemonic MUDPILES is commonly used to remember the

causes of increased anion gap metabolic acidosis M-Methanol U-Uremia (chronic renal failure) D-Diabetic ketoacidosis P-Propylene glycol ("P" used to stand for Paraldehyde but

substance is not commonly used today) I-Infection, Iron, Isoniazid L-Lactic acidosis E-Ethylene glycol (Note: Ethanol is sometimes included in this

mnemonic as well, although the acidosis caused by ethanol is actually primarily due to the increased production of lactic acid found in such intoxication.)

S-Salicylates

High Anion Gap

Another frequently used mnemonic is KARMEL.

K-Ketoacidosis A-ASA R-Renal failure M-Methanol E-Ethylene glycol L-Lactic acidosis

High Anion Gap

A 23-year-old woman with gastroenteritis experiences nausea and vomiting.  Aterial blood gas analysis is done 1 hour after the onset of symptoms.   Which of the following sets of blood gases is most likely.     

A  pH 7.30; PCO2 50; HCO3- 24

B pH 7.28; PCO2 40; HCO3- 18

C pH 7.56; PCO2 40; HCO3- 35

D pH 7.51; PCO2 50; HCO3- 35

Metabolic ABGS

Choice D is the best answer.  1. Vomiting causes loss of stomach acid

leading to metabolic alkalosis.  The rise in pH will inhibit the peripheral

chemoreceptor for pH located in the carotid bodies leading to hypoventilation (increased PCO2), which is compensatory.  

Answer

A 35-year-old man with type 1 diabetes is admitted to the emergency department after being found unconscious and unresponsive at home.  His breath has a "fruity" odor.  His wife told the EMTs that his diabetes had been "out of control" lately and that he has no other medical problems.  His breathing is deep and rapid.  An arterial blood sample is taken for analysis.  Which of the following sets of arterial blood gases is most likely.  

A  pH 7.00; PCO2 50; HCO3- 12

B pH 7.22; PCO2 30; HCO3- 12

C pH 7.56; PCO2 40; HCO3- 35

D pH 7.51; PCO2 45; HCO3- 35

Metabolic Acidosis

Choice B is the best answer.  The presentation is consistent with ketoacidosis (ketones are volatile acids that are eliminated via both kidneys and lungs).  The overutilization of fats for metabolism leads to ketoacidosis, a metabolic acidosis.  The low pH stimulates the carotid pH receptor leading to hyperventilation (lower PCO2) which is compensatory.  recall that according to the Henderson-Hasselbalch equation, pH = 6.1 + log [HCO3]/PCO2 x αlpha.  Compensation is always aimed at restoring the ratio HCO3/PCO2 back to a normal value, so if HCO3 decreases, PCO2 must decrease via hyperventilation to provide compensation.

Answer

CXR BNP ABG Cholesterol EKG/Echocardiogram Electrolytes CBC Vitals Tx: O2, Bipap, Diuretics, Inotropics

CHF

BNP BNP is a substance secreted from the

ventricles or lower chambers of the heart in response to changes in pressure that occur when heart failure develops and worsens. The level of BNP in the blood increases when heart failure symptoms worsen, and decreases when the heart failure condition is stable. The BNP level in a person with heart failure – even someone whose condition is stable – is higher than in a person with normal heart function.

Typically associated with CHF, depending on the patient often requires positive pressure for associated pulmonary edema. Typically non-invasive ventilation

Increased BNP

Vitals MONA EKG Echo Cardiac Enzymes Electrolytes CBC Tx: Stent, O2, CABG, Fibrolytic therapy

MI

Cardiac enzyme studies measure the levels of the enzyme creatine phosphokinase (CPK, CK) and the protein troponin in the blood.

Low levels of these enzymes and proteins are normally found in your blood, but if your heart muscle is injured, such as from a heart attack, the enzymes and proteins leak out of damaged heart muscle cells, and their levels in the bloodstream rise.

Because some of these enzymes and proteins are also found in other body tissues, their levels in the blood may rise when those other tissues are damaged. Cardiac enzyme studies must always be compared with your symptoms, your physical examination findings, and electrocardiogram (EKG, ECG) results.

Cardiac Enzymes

A liver (hepatic) function panel is a blood test to check how well the liver is working. This test measures the blood levels of total protein, albumin, bilirubin, and liver enzymes. High or low levels may mean that liver damage or disease is present.

The liver serves several important functions in the body, including changing nutrients into energy for the body and breaking down toxic substances.

Liver Failure

Elevated liver enzymes may indicate inflammation or damage to cells in the liver. Inflamed or injured liver cells leak higher than normal amounts of certain chemicals, including liver enzymes, into the bloodstream, which can result in elevated liver enzymes on blood tests.

The specific elevated liver enzymes most commonly found are: ◦ Alanine transaminase (ALT)◦ Aspartate transaminase (AST)

Elevated liver enzymes may be discovered during routine blood testing. In most cases, liver enzyme levels are only mildly and temporarily elevated. Most of the time, elevated liver enzymes don't signal a chronic, serious liver problem.

Liver Enzymes

Liver Failure

Acites, decreased sensorium

Albumin is a protein made specifically by the liver, It is the main constituent of total protein; the remaining fraction is called globulin (including the immunoglobulins).

Albumin levels are decreased in chronic liver disease, such as cirrhosis. It is also decreased in nephrotic syndrome, where it is lost through the urine.

Poor nutrition or states of impaired protein catabolism, may also lead to hypoalbuminaemia.

Albumin

Since the Prothrombin time test or PT test evaluates the ability of blood to clot properly, it can be used to help diagnose bleeding. When used in this instance, it is often used in conjunction with the PTT to evaluate the function of all coagulation factors.

Occasionally, the test may be used to screen patients for any previously undetected bleeding problems prior to surgical procedures.

The International Normalized Ratio (INR) is used to monitor the effectiveness of blood thinning drugs such as warfarin (COUMADIN®).

These anti-coagulant drugs help inhibit the formation of blood clots. They are prescribed on a long-term basis to patients who have experienced recurrent inappropriate blood clotting. This includes those who have had heart attacks, strokes, and deep vein thrombosis (DVT).

INR/PT

Metabolic encephalopathy is temporary or permanent damage to the brain due to lack of glucose, oxygen or other metabolic agent, or organ dysfunction. Most cases occur when the liver cannot act normally to remove toxins from the bloodstream during an acute illness, but it can also be caused by a toxic overdose, or other systemic disease.

Causes Metabolic encephalopathy occurs during significant metabolic

derangements, after some types of poisoning, and during diseases such as cirrhosis or hepatitis that slow or stop liver function, or diabetes, heart or renal failure.

It can also happen during medical conditions that cause blood circulation to bypass the liver. These problems keep the liver from removing toxins like ammonia, which build up in the blood as part of normal metabolism. High levels of these toxins can temporarily or permanently damage the brain, causing metabolic encephalopathy.

Metabolic encephalopathy

Patients will require intubation for airway protection

Risk for Sepsis

Metabolic encephalopathy

Disseminated intravascular coagulation (DIC)

Disseminated intravascular coagulation (DIC) is not a specific diagnosis, and its presence always indicates another underlying disease.

Disseminated intravascular coagulation (DIC) is characterized by a systemic activation of the blood coagulation system, which results in the generation and deposition of fibrin, leading to microvascular thrombi in various organs and contributing to the development of multiorgan failure.

Consumption and subsequent exhaustion of coagulation proteins and platelets, due to the ongoing activation of the coagulation system, may induce severe bleeding complications, although microclot formation may occur in the absence of severe clotting factor depletion and bleeding.

DIC