Common learning issues Test 5. MOSBY’S Arterial blood gases (p. 114-119) Monitor patients on ventilators, monitor critically ill nonventilator patients,

Common learning issuesTest 5

MOSBY’S

Arterial blood gases (p. 114-119)

• Monitor patients on ventilators, monitor critically ill nonventilator patients, establish preoperative baseline parameters, and regulate electrolyte therapy

• pH –log[H+]• Acids normally found in blood: carbonic, dietary, lactic and

ketoacids• Elevated indicates alkalosis• Decreased indicates acidosis• Normal pH: 7.35-7.45 (slightly larger range in infants and

children)• pH (Venous): 7.31-7.41 - It is more acidic b/c it contains more CO2

Blood gases• PCO2• Measure of partial pressure of carbon dioxide in the blood• Measure of ventilation (faster and deeper breathing removes

more CO2) PCO2 is a major medullary drive for respiration.• 10% free floating in plasma, 90% carried by RBCs• Respiratory component of acid-base determination• Co2 and pH are inversely proportional• Normal PCO2 = 35-45 mmHg (again infants and v. young children

wider range)• PCO2 (venous) = 40-50 mmHg• This is a measure of partial pressure, don’t confuse with HCO3-

concentration.

Blood gases• HCO3- (or CO2 content) Concentration• Measure of the metabolic component of the acid-base equilibrium• Regulated by the kidney• Directly proportional to pH (CO2 would be an indirect measure of bicarbonate)• In alkalosis kidneys excrete more into the urine to lower pH (compensating)• Adult Normal HCO3-: 21-28 mEq/mL (infants lower)

• PO2• Pressure of oxygen dissolved in plasma• Indirect measure of O2 content• Determines effectiveness of oxygen therapy• Determines the force of oxygen to diffuse across the pulmonary alveoli

membrane • Low if O2 diffusion difficulties (eg Pneumonia, shock lung, congestive failure)• Low if ventilation/profusion rations are off (under ventilated or over perfused

alveoli)• Normal PO2 = 80-100 mmHg (newborns less)• PO2 (venous) = 40-50 mmHg

Blood gases• Oxygen saturation

• Percentage of hemoglobin saturated with oxygen• As PO2 decreases so does saturation of hemoglobin (think about the sigmoidal shape of the

disassociation curve >75% stat, things are going very badly for the patient)

• Normal Adult/Child O2 saturation = 95%-100%• Oxygen content

• The amount of oxygen in the blood• Nearly all of it is bound to hemoglobin• Arterial: 15-22 vol%• Venous: 11-16 vol %

• Base excess/deficit• Amount of anions in the blood, bicarbonate being the largest. Also hemoglobin, proteins,

phosphates. • Normal Base Excess = 0 +/- 2 mEq/L• Negative base excess indicates metabolic acidosis (eg lactic acidosis)• positive alkalosis (either metabolic or compensation to prolonged respiratory acidosis)

• Alveolar to Arterial O2 difference • Normally should be <10 mmHg

How to interpret ABG levels • 1. Evaluation the pH

• If the pH is < 7.4 acidosis is present• If the pH is > 7.4 alkalosis is present

• 2. Next look at the PCO2 (careful: text same, order different from book)

• A. If the PCO2 is high with acidosis = Respiratory acidosis (primary problem is with decreased breathing eg drugs or lung disease)

• B. If the PCO2 is low with acidosis = Metabolic acidosis (with increased ventilation to blow off of CO2)

• C. If PCO2 is high with alkalosis = Metabolic alkalosis (with compensatory retention of CO2, down ventilation)

• D. If PCO2 is low with alkalosis = Respiratory alkalosis (Primary problem is hyperventilation)• 3. Next look at the bicarbonate ion (HCO3-)

• Respiratory acidosis you would expect to see high HCO3- [kidneys compensating with increased reabsorption]

• Metabolic acidosis you would expect to see a low HCO3- [lack of bicarb is part of primary problem Ex: diabetes, renal failure]

• Metabolic alkalosis you would expect to see a high HCO3- [excess bicarb is part of primary problem Ex: prolonged vomiting]

• Respiratory alkalosis you would expect to see a low HCO3- [kidneys decrease reabsorption to compensate]

Blood Carbon Dioxide (p152 – 153)

• From peripheral venous blood• Routinely obtained with CHEM 7 [DO NOT CONFUSE with

PCO2]• Is an indirect measure of HCO3- (also measures the v. small

amounts of H2CO3 and dissolved CO2 in serum)• HCO3- plays a major role in acid-base balance• Levels of HCO3- are regulated by the kidneys• Normal CO2 content = 23-30 mEq/L (mmol/L) [lower in kids-

infants]• Diuretics can either increase or decrease this depending on

the class. [briefly ones that Increase: Loop diuretics Decrease: thiazide diuretics + triamterene]

Blood Carbon DioxideIncreases

• Severe vomiting • b/c loss of acid in gastric secretions

• Hyperaldosteronism • b/c aldosterone acts on intercalated

cells to stimulate proton secretion that acidifies the urine and alkalizes extracellular fluid

• COPD • b/c compensatory increase for

chronic hypoventilation, PCO2 is high

• Metabolic alkalosis • Note: this is the definition of

metabolic alkalosis – an increase of HCO3- anions in blood

Decreases

• Chronic diarrhea• b/c loss of bicarb in lumen

• Chronic use of loop diuretics • b/c increases loss of basic ions into urine

• Renal failure• b/c inability to alkalize extracellular fluid

• Diabetic ketoacidosis & Starvation• b//c Ketoacids are neutralized by bicarb

and it lowers the amount in serum

• Shock • b/c lactic acid that builds up is buffered

by bicarb

• Metabolic Acidosis • Note: this is the definition of metabolic

acidosis – a decrease of HCO3- anions in blood

Blood chloride (p164-165* pages provided were incorrect)

• Normal Cl- = 98-106 mEq/L (mmol/L) [Slightly wider range for children]

• Performed in a CHEM 7• Chloride is the major extracellular anion• It’s primary purpose is to maintain neutrality (it often replaces

HCO3- intracellularly if bicarbonate is needed to buffer carbon dioxide.

• Hypoclhloremia or hyperchloremia rarely occur alone and usually correspond to sodium or bicarbonate changes.

Blood ChlorideHypochloremia• Signs and symptoms:

• Hyperexcitablity of nervous system and muscles

• Shallow breathing • Hypotension• Tetany

• Causes:• Over hydration• SIADH• Congestive heart failure• Vomiting• Chronic diarrhea • Chronic respiratory acidosis• Metabolic alkalosis (b/c chloride is driven into the

cell to compensate for the HCO3- that leaves the cell to maintain blood pH)

• Salt-losing nephritis• Addison’s disease• Diuretic therapy• Hypokalemia• Aldosteronism• Burns (b/c sodium and chloride lost from burns can be

great)

Hyperchloremia • Signs and symptoms:

• Lethargy• Weakness• Deep breathing

• Causes:• Dehydration• Excess normal saline infusion• Metabolic acidosis• Renal tubular acidosis• Cushing syndrome• Hyperparathyroidism• Eclampsia (b/c chloride urinary excretion is

decreased)• Respiratory alkalosis (b/c Chloride is

driven out of the cell in place of HCO3-)

Cholesterol (p166 – 167)• Normal Findings:

Adult: <200 mg/dL• Needed for production of steroids, sex hormones, bile acids, and cellular

membranes • The main lipid associated with arteriosclerotic disease• Metabolized by the liver• 75% bound inside LDL and 25% is in HDL• Main component of LDL (minimal in HDL and VLDL)• Testing is typically part of a lipid profile (by itself is not an accurate predictor of heart

disease) [Ex: someone can have high cholesterol with high HDLs but low LDLs]• An Individual‘s cholesterol levels can vary daily by 15%. Positional changes affect

levels (15% decrease seen in lateral recumbent position, often seen in hospitalized patients)

• Repeat tests should be done for abnormal values and an average will be established• Used to predict risk of CHD within the Framingham Coronary Prediction algorithm

(determines overall risk of ischemic event)

Cholesterol • Increased levels:

• liver disease, pregnancy, oorophorectomy, postmenopausal status, familial hyperlipidemias or hypercholesterolemias, hypothyroidism, uncontrolled diabetes mellitus, nephrotic syndrome, xanthomatosis, hypertension, atherosclerosis, biliary cirrhosis, stress

• Drugs that increase levels:• adrenocorticotropic hormone, anabolic steroids, beta-adrenergic blocking agents,

corticosteroids, cyclosporine, epinephrine, oral contraceptives, phenytoin, sulfonamides, thiazide diuretics, and vit D

• Decreased levels: • liver disease, malabsorption, malnutrition, acute myocardial infarction (6-8 weeks following),

advanced cancer, hyperthyroidism, cholesterol-lowering medication, pernicious anemia, hemolytic anemia, sepsis, stress,

• Drugs that decrease levels:

• allopurinol, androgens, bile salt-binding agents, captopril, chlorpropamide, clofibrate, colchicine, colestipol, erythromycin, isoniazid, liothyronine, MAO inhibitors, niacin, nitrates, and statins

Blood Sodium (479 – 482)• Blood Sodium (measured in a CHEM 7)

Adult/Ederly/children: 136-145 mEq/L (mmol/L)Infant (134-150), and Newborn (134-144)Critical: <120 or >160 mEq/L

• Major cation of the extracellular space (values as above; intracellular value of only 5 mEq/L) Sodium salts are the major determinates of extracellular osmolality.

• Dietary intake must be balanced with renal excretion. Sodium lost from sweat is normally minimal.

• Aldosterone causes conservation of sodium through reabsorption in the kidneys• Natriuretic hormone is stimulated by high sodium levels and decreases renal

absorption• ADH controls the reasborption of sodium at the distal tubules of the kidney (dilution

or concentration)

• the 1st symptom of hyponatremia (signs begin <125) is weakness and may then progress to (<115) confusion, lethargy, stupor, or even coma

Blood Sodium• Causes of Hypernatremia:

• increased sodium intake• Excess sodium in IV fluids • Increased dietary intake

• decreased sodium loss • Cushing syndrome• Hyperaldosteronism

• excessive free body water loss • excessive sweating • thermal burns• diabetes insipidus• osmotic diuresis

• Drugs that may increase levels: anabolic steroids, antibiotics, carbenicillin, clonidine, corticosteroids, cough medicine, estrogens, laxatives, methyldopa, and oral contraceptives

• Also recent trauma, surgery, or shock may cause increased levels because renal blood flow is decreased

• Cause of Hyponatremia: • decreased sodium intake • increased sodium loss

• Addison disease• Diarrhea• Vomiting• nasogastric aspiration• intraluminal bowel loss• diuretic administration• chronic renal insufficiency

• increased free body water• excessive oral or IV H2O intake• Hyperglycemia• Congestive heart failure• peripheral edema• Ascites, peripheral edema, pleural effusion• Intraluminal bowel loss• SIADH – over secretion of ADH

• Drugs that may decrease levels: ACE inhibitors, captopril, carbamazapine, diuretics, haloperidol, heparin, NSAIDs, sodium free IV fluids, sulfonylureas, triamterene, tricyclic antidepressants, and vasopressin

Treatment of Hyponatremia: water restriction

Triglycerides (521 – 522) Adult: Male 40-160 mg/dL Female 35-135 mg/dLCritical: >400 mg/dL

• Produced in the liver using fatty acids and glycerol• Transported by VLDL and LDL• When levels are high, triglycerides are deposited in fatty tissues. Act as storage of energy.• Constitute most of the fat of the body • Measured as part of a lipid profile

• Interfering factors:• ingestion of fatty meals can cause elevated TG levels• ingesting alcohol causes increased VLDL levels, which increases TG• Pregnancy causes increased levels• Drugs causing increased TG levels: estrogen, oral contraceptives, cholestyramine• Drugs causing decreased TG levels: ascorbic acid (vit C), asparaginase, clofibrate, fibrates,

statins.

Children (yr) Male (mg/dL) Female (mg/dL)

0-5 30-86 32-99

6-11 31-108 35-114

12-15 36-138 41-138

16-19 40-163 40-128

Triglycerides, pp. 521-522 • Increased levels:

• Ingestion of fatty meals, alcohol, pregnancy• Glycogen storage disease

• Von Gierke disease (VLDL synthesis is increased and catabolism is decreased)• Apoprotein CII deficiency

• (can’t activate LPL to unload the apoproteins so they accumulate in blood)• Hyperlipidemias, familial hypertriglceridemia• Hypothyroidism• High carb diet• Poorly controlled diabetes

• (VLDL synthesis is increased and catabolism is decreased)• Nephrotic syndrome

• (the fall in oncotic pressure seems to stimulate the liver to produce VLDLs and LDLs)• Chronic renal failure

• (insulin is excreted by the kidney, so in these patients insulin is high and it stimulates lipogenesis)

• Decreased levels: • Malabsorption• Malnutrition• Abetalipoproteinemia• Hyperthyroidism (catabolism of VLDLs increases therefore TGs blood levels fall)

Secretin-Pancreozymin (701-702)• This is a corroborative test used in the evaluation of Cystic Fibrosis. It is

indicated in children with recurrent respiratory tract infections, malabsorption syndromes, or failure to thrive.

• Secretin and Pancreozymin are used to stimulate pancreatic secretions. The duodenal contents are then aspirated and examined for pH, bicarbonate, and enzyme levels. • Secretin can be expected to stimulate pancreatic water and bicarbonate

secretion• Pancreozymin can be expected to stimulate pancreatic enzyme (lipase, amylase,

trypsin, chymostrypsin) secretion

• Amylase is the most frequently measured enzyme

• Diminished values are suggestive of Cystic Fibrosis• Due to the development of mucosal plugs pancreatic enzymes, bicarbonate can

not be secreted from the pancreas.

Sweat electrolytes (711-713)

• Children: sodium: <70 mEq/L (abnormal >90)chloride: <50 mEq/L (abnormal >60)

• Sensitive and specific test used to diagnose Cystic Fibrosis• does not measure the severity of the disease

• Test is indicated in children with recurrent respiratory tract infections, chronic cough, early onset asthma, malabsorption issues, late passage of meconuim stool, or failure to thrive

• CF patients will have increased sodium and chloride contents in their sweat

• Sweat, induced by electrical current (pilocarpine iontophoresis), is collected, and the sodium and chloride contents are measuredThe• positive electrode is saturated with pilocarpine hydrochloride, a drug that induces sweating• The negative electrode is saturated with a bicarbonate solution• The electrical current flows for 5-12 mins• Then paper disks with a paraffin airtight seal are placed over the test site for 1 hr. Then the paper is analyzed.

• Test MUST be done multiple times to be useful as a diagnostic tool• In normal individuals, sweat produced at the bottom of a sweat duct is rich in sodium and chloride, but as it moves through the duct, the

chloride (followed by sodium)is transported through the cells lining the duct out of the sweat. This leaves behind water.• In CF patients, the epithelial lining cells in the sweat ducts fail to take up the electrolytes, leaving a high sodium and chloride content

• A screening test to detect chloride levels can be done by pressing paper containing silver nitrate against the child's hand for several seconds. A positive test occurs when the child leaves a white powder, "heavy" handprint on the paper. Positive screens are followed up by iontophoresis

• Other conditions that can have abnormal sweat tests include: • G6PD deficiency• Adrenal hypofunction• Glycogen storage diseases

• A cold room or dehydration can alter results. Adolescents going through puberty can have variable results and are not measured accurately.

Urine Osmolality (980-981)Urine Osmolality• 12-14 hr fluid restriction: >850 mOsm/ kg H2O• Random specimen: 50-1200 mOsm/ kg H2O (depending on fluid intake)

• This test is an accurate determination of the kidney's concentration capabilities

• Also used to evaluate ADH abnormalities and fluid and electrolyte balance• Measures the number of dissolved particles in the urine• Most commonly measured by determining the freezing point

• More exact measurement of urine concentration than specific gravity• because specific gravity depends on the weight and density of particles,

temperature, and requires correction for presence of glucose or protein

• Urine osmolality is more easily interpreted when the serum osmolality is simultaneously measured • Normal ratio of urine to serum osmolality of 1:3

Urine Osmolality• Increased levels:

• SIADH • ADH is inappropriately secreted despite factors normally would inhibit its secretion. As a result,

large quantities of water are reabsorbed by the kidney. (Low serum, high urine)• Shock

• The normal response minimizes the loss of free body water. The kidney therefore absorb all the free water possible.

• Hepatic cirrhosis and CHF• These illnesses are associated with water retention because of reduced perfusion of the kidneys.

• Paraneoplastic syndromes associated with carcinoma • Ectopic secretion of ADH.

• Decreased levels: • Diabetes insipidus

• Insufficient secretion of ADH in context of high serum osmolality, kidneys have diminished concentrating ability (high serum, low urine)

• Excess fluid intake• Renal tubular necrosis• Severe pyelonephritis

• When kidneys are damaged the concentrating ability can be diminished

Blood Culture and Sensitivity (p 747-749)• Bacteremia can be intermittent and transient, except in endocarditis or

suppurative thrombophlebitis. • Episodes of bacteremia are usually accompanied by chills and fever. Blood

drawn at times with these signs increases the likelihood of yielding bacteria on culture.

• Draw at least 2 samples from 2 different sites. This helps eliminate growth that may occur as a result of contamination. When both cultures grow the infecting agent, bacteremia exists and is a result of that organism.

• If the patient is currently receiving antibiotics, resin can be added to the culture medium to negate the antibiotic effect in the culture.

• Cultures ideally are drawn before initiating antibiotics. • Blood drawn from IV catheters are frequently contaminated. Only draw blood

from these in cases of suspected catheter sepsis to help identify the causative organism.

• Most organisms require 24hrs to grow. 48-72 hours are required for growth and identification of the organism. Anaerobic organisms may take longer to grow.

Sputum Culture and Sensitivity(p 802-804)• Indicated in patients with persistent productive cough, fever,

hemoptysis, or a chest x-ray picture compatible with a pulmonary infections.

• A gram stain is the first step in analysis• The sample is then plated on several plates, bacteria that grow

is later identified. Preliminary reports usually after 24 hours.• After 1-3 days of growth drug sensitivity testing is performed to

identify the most appropriate antibiotic treatment. Cultures require at least 48 hours for completion. • Antibiotic plugs (small infused disks) are put onto the plate. The

ring of inhibited growth around the disk indicates that the bug is sensitive to that drug.

Note: culture for Mycobacterium tuberculosis (TB) take 6-8 weeks.

Stool culture (p896-898)• Usually performed on patients with unrelenting diarrhea, fever and abdominal bloating. Especially if patient has traveled

outside the USA, has been drinking well water, or has been receiving prolonged course of antibiotics. • The normal stool flora can become pathogenic is bacterial overgrowth occurs as a result of antibiotics or

immunosuppression.

• Most common bacteria in stool: (in no particular order)• Enterococcus• Escherichia coli• Proteus• Pseudomonas• Staphylococcus aureus• Candida albicans (fungus)• Bacteroides• Clostridium

• Pathogenic Bacteria:• Salmonella• Shigella• Camplylobacter• Yersinia• Pathogenic E. coli, Clostridium, and Staphylococcus

• Common parasites in stool:• Ascaris (hookworm)• Strongyloides (tape worm)• Giardia (protozoans)• Cryptosporidium (esp in AIDs patients)

Note C. difficile normal in stool, problem when overgrown. H. Pylori can be found in stool, usually better cultured from stomach or determined by serologic blood test.

Stool Culture• Tape test:• Tests for Pinworms (Enterobius)• Clear tape in patient’s perianal region at night before bedtime.

Remove it in the AM before patient leaves bed. Female worm lays eggs at night around this region.

• Press sticky side directly onto a glass slide. • Can take up to 6 weeks to isolate.

• Parasitic enterocolitis:• These organisms can be grown on a special culture plates. Can

also be detected in smears of stool.

Urinalysis (p1000-1016)

• Normal: • Appearance: clear• Color: amber yellow• Odor: aromatic• pH: 4.6-8.0 (avg 6.0)• Protein: 0-8 mg/dL

• 50-80 mg/24 hr (at rest)• <250 mg/24 hr (during

exercise).• Specific gravity: Adult 1.005-

1.030 (usually, 1.010-1.025)• Elderly: values decrease with

age• Newborn: 1.001-1.020

• Leukocyte esterase: negative • Nitrites: none• Ketones: none• Bilirubin: none• Urobilinogen: 0.01-1• Crystals: none• Casts: none• Glucose: Fresh sample – none

• 24 hr spec – 50-300mg/24hr• WBCs: 0-4 low power field• RBCs: <2• RBC casts: none

Urinalysis • Indications: used as part of routine diagnostic and screening evaluations

can give info on kidneys, performed on essentially everyone• If UTI is suspected a clean-catch specimen is obtained and divided. Half is

sent to UA the other half is cultured.• Laboratory:

• Appearance: should be clear, cloudy indicates WBC, RBC or bacteria. Can also be cloudy due to some food.

• Color: color indicates concentration (urochrome) of urine and varies with specific gravity. Dilute is straw colored and concentrated is deep amber.• abnormal color may indicate bleeding from kidney (dark red) bleeding from

lower UT (bright red)• Dark yellow indicates urobilinogen or bilirubin• Pseudomonas could cause green urine• Beets cause red urine, rhumbarb causes brown urine• Porphyria can cause wine-colored or even dark brown urine• Chart on p 1002 goes over common drugs that change urine color.

• Ex (most commonly mentioned from all sources): Rifampin= red/orange urine

UA• Odor: normal odor caused by presence of volatile acids.

• Diabetic ketoacidosis have strong, sweet smell of acetone• UTI causes foul odor• Fecal odor could be a fistulas• Long standing if breaks down and begins to smell like ammonia• Some food have characteristic urine odors• Genetic disease: Maple syrup urine disease and Phenylketouria

• pH• Kidneys help maintain normal pH homeostasis. They assist in in acid-

base balance by resorbing sodium and excreting hydrogen. • Alkaline urine: indicates alkalemia, bacteria, UTI or citrus fruits or

vegetables, common after eating• Alkaline causes calcium carbonate, phosphate and magnesium

phosphate stones• Acidic urine: dehydration, high meats and cranberries,

UA• Protein

• Indicates if glomerular membrane is intact like in glomerularnephritis, protein then seeps into urine and can lead to hypoproteinemia which decreases capillary oncotic pressure causing edema called nephrotic syndrome

• Proteinuria indicates renal disease or preeclampsia • Indicates complications of DM, glomerularnephritis, amyloidosis, multiple myeloma• Most commonly lost protein is albumin• Over 24 hour period if protein lost is >3000mg/24hrs patient has nephrotic syndrome. • Compared to creatinine to control for other factors such as hydration status

• Normal protein/creatinine ration is less than 0.15

• Specific gravity• High indicates concentrated urine• Low is dilute urine• Weight of urine compared to that of pure water• Chronic diseases associated with low specific gravity measure of hydration status• Dehydration causes it to be really high

• Leukocyte esterase• Positive indicates UTI. Tests form WBCs in urine.

UA• Nitrites

• Screening for UTI, bacteria produce reductase converting nitrates to nitrites

• Ketones• Poorly controlled diabetes and hyperglycemia, massive fatty acid

catabolism• Bilirubin and urobilinogen

• Conjugated bilirubin is water soluble, indicates disease affecting bilirubin affecting bilirubin metabolism after conjugation or defects in excretion indicate previously suspected liver disease, gallstones, or drug toxicity

• Crystals• Indicate renal stone formation is imminent• Can be with high serum uric acid levels• Parathyroid causes high phosphate and calcium crystals

Urinanalysis: Casts• Casts

Rectangular clumps that form renal distal and collecting tubules, pH must be acidic and urine concentrated. Always indicate renal origin.• Hyaline

• Conglomerations of protein, proteinuria• Cellular

• Conglomerations of degenerated cells• Granular

• After exercise and renal disease, result from disintegration of cellular material into granular particles within a WBC

• Fatty• Some diseases epithelial cells desquamate into renal tubule fatty droplets become free oval fat bodies or

incorporated into proteins associate with nephrotic syndrome or nephrosis, fatty emboli or bone fractures• Waxy

• Cell, hyaline, renal failure or further degeneration of granular casts, associated with chronic renal disease and renal failure or diabetic nephropathy, malignant hypertension, and glomerularnephritis

• Epithelial• Shed from bladder from tumor, infection, or polyps• Tubule epithelial casts indicate glomerulonephritis

• WBC• Five or more indicate UTI involving bladder, kidneys, or both• Inflammatory nephritis, glomerulonephritis • pyelonephritis

• RBC• Bladder, urethral, and ureteral disease, tumor, trauma stones infection, glomerloneprhitis, renal infarct,

goodpasture, vasculitis, sickle cell, interstitial nephritis, tubular necrosis, pyelonephritis

Urinalysis: quick associations• Bilirubin: Jaundice, hepatitis, fecal contamination of sample• Blood: Stones, BPH, infection, Foley cath• Glucose: DM, pancreatitis, steroids• Ketones: Starvation, high fat diet, diabetic ketoacidosis,

vomiting, diarrhea, aspirin overdose• Leukoesterase: UTI• Leukoesterase plus nitrates: 75% of UTI• Neither LE or nitrates: 92% not UTI

• Protein: Renal failure, CHF

• Glucose, Ketones, Leukoesterase and bilirubin in urine is never normal

Arteriography (p1039-1043)• Injection of radiopaque contrast material (usually iodinated

CO2 can be used and an alternative) into arteries, blood vessels can be visualized to determine arterial anatomy, vascular disease or neoplasms.

• Catheter femoral or brachial artery and injected while x-ray films are being obtained.

• Can see:• Blood flow dynamics• abnormal blood vessels• vascular anomalies• Normal and abnormal vascular anatomy • Tumors

Arteriography• Digital subtraction angiography (DSA)

• Allows bony structures to be removed from images, this enables better visualization of arteries especially the carotid and cerebral arteries

• Renal Angiography• Differentiate cysts from hypervascular cancers (Highly vascular tumors can produce a “blush” of

contrast material)• Evaluate blood flow dynamics

• Adrenal Angiography• Hyperplasia, benign or malignant neoplasms can be detected • Risk of hemorrhage leading to adrenal insufficiency• With pheochromocytomas risk or hypertensive crisis

• Cerebral Angiography• Injected into carotid or vertebral arteries • To ID: Aneurysms, occlusions, stenosis, AVMs, vascular and non-vascular tumors, abscesses,

hematoma• Lower-Extremity Angiography

• Allows identification and location of occlusions within the abdominal aorta and lower-extremity arteries. Also Aneurysmal dilations, arterial trauma such as intimal tearing, emboli.

• Some vasculitis show up as characteristic “beading”

Note that iodinated contrast is nephrotoxic

DRUGS TO KNOW

Drug Uses Side effects Contraindications Therapeutic considerations

CaptoprilPg 349

Class: ACE inhibitorMech: decreases conversion of AT I to AT II decreasing arteriolar vasoconstriction, aldosterone synth, renal proximal tubule NaCl reabsorp. and ADH release. Also inhibit degradation of the vasodilator, BradykininIndications:• Hypertension• Heart failure• Diabetic Nephropathy• Myocardial Infarction

• Angioedema (more frequent in black patients)

• Agranulocytosis• Neutropenia• Cough• Edema• Hypotension• Rash• Gynecomastia• hyperkalemia

• History of angioedema• Bilateral renal artery

stenosis• Renal failure• pregnancy

• Given as active drug and processed to active metabolite

• Cough and angioedema caused by bradykinin action

• Hyperkalemia risk increased when used with potassium-sparing diuretics

• First-dose hypotension more common in patients with bilateral renal stenosis

FurosemidePg 351

Class: Loop diureticMech: reversibly and competitively inhibit Na+/K+/Cl- co-transporter in apical membrane of thick ascending limbIndication: • Hypertension• Acute pulmonary edema• Edema from heart failure,

hepatic cirrhosis, or renal dysfunction

• Hypercalcemia• Hyperkalemia

• Hypotension• Pancreatitis• leukopenia• Volume contraction

alkalosis• Hypokalemia• Hyperuricemia• Hypomagnesemia• Hyperglycemia• Glycouria

• Co-admin with aminoglycosides increases ototoxicity and nephrotoxictiy

• Sulfonamide derivative• Front-line therapy for

listed indications• Can counteract

hypercalcemic and hyperkalemic states


Cefazolin

First Aid:1st GenCephalosporinsGram (+) and “PEcK”

Class: Cephalosporins have a six-membered accessory ring attached to the Beta-lactam ring.Mech: Beta-lactams inhibit transpeptidase by forming a covalent (“dead-end”) acyl enzyme intermediateIndication: •Proteus mirabilis•E. Coli•Kiebsiella pneumoniae

•Skin and soft-tissue infections•Surgical prophylaxis

• Pseduomembranous enterocolitis

• Leukopenia• Thromobocytopenia• Hepatotoxicty• Nausea• Vomiting• Diarrhea• Rash

• Hypersensitivity to cephalosporins (rarely crose-react with penicillins)

• First-generation cephalosporins

• Relatively good Gram-positive coverage

• Sensitive to many beta-lactamases

Ciprofloxacin pg596

Class: Quinolones: inhibitor of topoisomeraseMech: inhibit bacterial type II topoisomerases; causing dissociate of Top II (DNA gyrase) from cleaved DNA, leading to double stranded breaksand cell deathIndication: • Gram (-) infections• Common Upper Resp

Infections• UTI• GI infections

• Cartilage damage• Tendon rupture• Periph. Neuropathy• Increased Intracranial

pressure• Seizure• Severe hypersensitivity

reaction• Rash• GI disturbance

(Nausea/ Vomiting, diarrhea)

• Co-admin with tizanidine• Hypersensitivity

• Resistance: thru chromosonal mutations in genes that encode type II tops, or thru alterations in expression of membrane porins and efflux pumps that determine drug lvls in bacteria

• Bacteriostatic at low conc. • Bactericidal at high conc.


Metronidazole

From first aid(used for anaerobes below the diaphragm)

Pharm 1-liners(DOC for pseudomembranous enterocolitis – C. diff)

Class : NitroimidazoleMech: activated by enzymes in parasites and anaerobic bacteria to form reduced cytotoxic compounds (ROS) that damage microbial proteins, membranes, and DNA. Indication: • Anaerobic bacteria• Amebiasis• Giardiasis• Trichomoniasis

• Leukopenia• Thrombocytopenia• Ototoxicity• Disulfiram-like effect

with alcohol• gastrointestinal

disturbance• Handache,• Neuropathy• Metallic taste• Vaginitis

• Hypersensitivity to metroniazole or other nitromidazole agents

• Hypersensitivity to parabens (gel formulation)

• First trimester of pregnancy• Concomitant alcohol

administration leads to disulfiram-like reaction

• Active against E. histolytica trophozoites in tissues, but much less active against intraluminal ameba

• Individuals with invasive amebiasis are typically treated first with mitronidazole and then with a second agent such as iodoquinol or paromomycin

ClonidinePg 144

Class: alpha2 adrenergic agonistMech: selectively activate central alpha2-adrenergic auto-receptors to inhibit sympathetic outflow from CNSIndication: • Hypertension• Opioid withdrawal• Cancer pain

• Bradycardia• Hypotension• Heart failure• Hepatotoxicity• (side effects related

to depressed sympathetics and increased vagal response)

• Not listed • Used for HTN and symptoms of opioid withdrawal


Linezolid Class: OxazolidinonesMech Exact mechanism remains uncertainIndications:• Gram-postive bacterial infectionsEspecially • vancomycin-resistant enterococcus• Methicillin-resistant S. aureus

(MRSA)• S. agalactiae• S. pneumoniae (including multidrug

resistant strains)• S. pyogenes• Nosocomial pneumonia• Complicated diabetic foot infections

• Myelosuppression• Peripheral

neuropathy• Optic neuropathy• Gastrointestinal

disturbances• Headache

• Hypersensitivity to linezolid

• Linezolid is available in both oral and IV formulations

CisplatinPg 696

Class: Directly modify DNA structure Mech: Platinum compound that cross-links intrastrand guanine basesIndications:• Genitourinary • Lung cancer

• Nephrotoxicity• Myelosuppression• Peripheral

neuropathy• Ototoxicity• Electrolyte

imbalance

• Severe bone marrow depression

• Renal or hearing impairment

• Can be injected intraperitoneally for treatment of ovarian cancer

• Co-administration of amifostine can limit nephrotoxicity

Etoposide aka VP-16Pg 691 & 697

Class: Antineoplastic agent: Topoisomerase inhibitorMech: bind topoisomerase II and DNA, trapping the complex in its cleavable stateIndications:• Lung cancer• Testicular cancer• Leukemia

• Heart failure• Myelosuppression• Alopecia (hair loss)• Rash• GI disturbance

• hypersensitivity • Class breakdown:• Antineoplastic->

topoisomerase inhibitors-> epipodophyllotoxin

• Action is specific to late S and G phases of cell cycle


Vancomycin pg614

Class: Inhibitor of murein polymer synthesisMech: Bind to D-Ala-D-Ala terminus of the murein monomer and inhibit PGT preventing addition of murein units to the growing chainIndication: • MRSA (IV admin)• Serious skin infections

involving staph or strep (IV admin)

• C. Difficile enterocolitis(oral)

• Neutropenia• Ototoxicity• Nephrotoxicity• Anaphylaxis• “Red-man syndrome”

(flushing and erythroderma)

• Drug fever• Hypersensitivity rash

• Co-admin with Gentamycin• Solutions containing

dextrose in patients with known corn allergy

• Increased nephrotox with aminoglycosides

• “red-man syndrome” can be avoided by slowing infusion rate or preadministering antihistamines

• Resistance: arises thru acquisition of DNA encoding enzymes that catalyze formation of D-Ala-D-lactate

• Used for Gram (+) rods and cocci

• Gram(-) rods are resistant

MethicillinPg 615

Class: Penicillins: inhibitors of polymer cross-linkingMech: Beta-Lactams inhibit transpeptidase by forming a covalent (“dead-end”) acyl enzyme intermediateIndication: • Skin and soft tissue

infections or systemic infection with B-lactamase- producing methicillin-senstive S. aureus

• All side effects listed are for the other drugs in this class

For boards this drug is important because of the resistance of MRSA. Methicilin is actually quite toxic (acute interstital nephritis) and rarely used clinically.• MRSA has the gene

mecA which changes the binding site.

• Hypersensitivity to penicillins

• Beta-lactamase resistant (staphlococcal)

• Narrow-spectrum antibacterial activity

• Gram (+) only• Is a hydrophobic

substance• Penicillins have a 5-

membered ring attached to the beta-lactam ring


TrimethoprimPg 579

• “Bactrim” =Trimethoprim/Sulfamethoxazole

Class: Antimicrobial dihydrofolate reductase inhibitorMech: folate analogue; competitively binds microbial DHFR to prevent regeneration of tetrahydrofolate from dihydrofolateIndications:• Urinary Tract Infection

• Stevens-Johnson syndrome

• Leukopenia• Megaloblastic anemia• Rash• pruritus

• Megaloblastic anemia due to folate deficiency

• Used with medication below to limit resistance development

• Excreted unchanged into urine

SulfamethoxazolePg 579

• “Bactrim” =Trimethoprim/Sulfamethoxazole

TMP/SMX is an acceptable appreivation

Class: Antimircrobial dihydropteroate synthase inhibitorMech: PABA analogue that competitively inhibit microbial dihydropteroate synthase and thereby prevent the synthesis of folic acidIndications: • Pneumocystis carinii

pneumonia (CD4<200)

• Shigellosis • Traveler’s diarrhea• UTI• Granuloma inguinale• Acute otitis media

• Kernicterus in newborns

• Brain damage in newborns

• Crystalluria• Stevens-Johnson

syndrome• Agranulocytosis• Aplastic anemia• Hepatic failure• GI disturbance• rash

• Infants less than 2 months old

• Pregnant women at term• Breastfeeding• Megaloblastic anemia due

to folate deficiency• Co-administration with

PABA

• Used with medication above to limit resistance development

• Indications listed for TMP/SMX combinations

• Compete with bilirubin for binding sites on serum albumin and can cause kernicterus in newborns; can also cause brain damage

Mietzner guide to bacterial tests Directly from his powerpoint

4/16/2013

Catalase Test

• Detects the presence of catalase, and enzyme the converts hydrogen peroxide to water and oxygen. The liberated oxygen causing bubbles.

Differentiates

-Streptococci (-) from Staphylococci (+)

-Clostridia (-) from Bacillus (+)

4/16/2013

Catalase Test

Rod

Gram Positive

Cocci

Staphylococcus

Catalase Test

Positive PositiveNegative

Clostridia

Negative

BacillusStreptococcus

4/16/2013

COAGGULASE Test• Detects the presence of coagulase. This enzyme acts with a

plasma factor to convert fibrinogen to a fibrin clot• Used to differentiate Staphylococcus aureus (pos) from

Staphylococcus epidermidis (neg)

Documents

Common learning issues Test 5. MOSBY’S Arterial blood gases (p. 114-119) Monitor patients on ventilators, monitor critically ill nonventilator patients,