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Common learning issues

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1 Common learning issues
Test 2

2 Mosbys

3 Anion gap (pages 66-67) Assists in the evaluation of patients with acid-base disorders Attempts to identify cause of the disorder and also to monitor therapy for acid-base abnormality Test explanation: Difference between anions and cations in extracellular space (sodium + potassium) – (chloride + bicarbonate) Test should be adjusted downwards if potassium is eliminated from test Bicarb is actually venous CO2 not arterial bicarb Determines cause of metabolic acidosis The build up of ketoacids and lactic acid will cause increased AG Albumin is one of the leading factors in increasing AG Nephrotic syndrome ( decrease in anions) or increased calcium or magnesium will cause decreased AG Low anions causes increased bicarb Hypoproteinemia and increased immunoglobulins can lower AG Gives a complex metabolic picture along with ABG Interfering factors: Decreasing factors: hyperlipidemia, acetazolamide, lithium, polymyxin B, spironolactone, and sulindac Increasing factors: carbenicillin, carbonic anhydrase inhibitors (acetaloamide), diuretics, ethanol, methanol, penicillin, and salicylate

4 Blood glucose ( ) Direct measure of blood glucose used mainly for diabetic patients Test explanation: Glucose levels are low in the fasting state which causes glucagon release by pancreatic alpha islet cells Glucagon breaks glycogen down to glucose in the liver If fasting persists, proteins and fatty acids are broken down under glucagon stimulation Glucose levels are elevated after a meal causing a release of insulin from pancreatic beta cells Insulin causes up-regulation of insulin receptors and glucose uptake into mainly muscle, brain, and adipose tissue ACTH, adrenocorticosteroids, epinephrine, growth, and thyroxine affect glucose Must be evaluated for the time of day True glucose elevation is usually DM Hypoglycemia is inadvertent insulin overdose in patients with brittle diabetes Must monitor frequently in diabetes patients Finger stick blood glucose are performed before meals and at bedtime Interfering factors: Increased levels: Stress (trauma), general anesthesia, infection, burns, MI, caffeine, pregnancy, IV dextrose, antidepressants, beta blockers, corticosteroids, dextrothyroxine, diazoxide, diuretics, epinephrine, estrogens, glucagon, isoniazid, lithium, phenothiazines, phenytoin, salicylate, and triameterene Decreased levels: acetaminophen, alcohol, alpha glucosidase inhibitors, anabolic steroids, biguanides, clofibrate, disopyramide, gemfibrozil, incretin mimetics, insulin, MAOi, meglitinides, pentamidine, propanolol, sulfonylurea, and thiazolidinediones

5 Glucose, postprandial (270-271)
The 2 hour test is a measurement of the amount of glucose in the patient’s blood 2 hours after a meal is ingested (postprandial) Test explanation: The meal acts as a glucose challenge to the body’s metabolism Insulin is normally secreted after a meal in response to the high blood glucose In diabetes patients the glucose is usually still elevated 2 hours later If the levels are between then a glucose tolerance test must be obtained If the levels are greater than 200 then a diagnosis of DM is made 1 hour test detects gestational diabetes The detection of gestational diabetes prevents excessive fetal growth and birth trauma, fetal death, neonatal morbidity O’ Sullivan test gives a 50 g oral glucose dose and tests 1 hour later weeks gestation; a 3 hour test is ordered for levels above 140 Interfering factors Increasing factors: smoking during testing, stress, eating a snack or candy Falsely decreased if the person cannot eat the entire test meal or vomits

6 Glucose tolerance test (275-278)
Assists in the diagnosis of DM and the evaluation of patients with hyperglycemia Test explanation: Criteria to diagnose diabetes: Sufficient clinical symptoms ( polydipsia, polyuria, ketonuria, weight loss) plus random blood glucose > 200 Elevated FBG on more than one occasion 2 hour glucose > 200 Used when diabetes in expected (retinopathy, neuropathy, renal disease) but criteria for diagnosis can’t be met without GT May be used for the following Family history of diabetes Patients who are massively obese History of recurrent infections Delayed healing of wounds Women who have stillbirths or large babies Transient glycosuria or hyperglycemia during pregnancy, or following MI, surgery or stress The ability to tolerate glucose load is evaluated through serum and urine glucose levels at 30 minutes, 1, 2, 3, and 4 hours Normally there is a rapid insulin response that peaks in minutes and returns to normal in 3 hours, glucose shouldn’t spill into urine

7 Glucose tolerance test (275-278) cont.
Test explanation: Patients with diabetes won’t tolerate this load so their serum levels remain high; glucose spills into urine Some patients cannot tolerate oral dose (gastrectomy, short bowel syndrome, malabsorption) so they’re given an IV dose Cushing’s , pheocromocytoma, acromegaly, aldosteronism, or hyperthyroidism may all cause glucose intolerance Chronic renal failure, acute pancreatitis, myxedema, type IV lipoproteinemia, infection or cirrhosis cause abnormal GT test Contraindications Serious concurrent infections or endocrine disorders (glucose intolerance) Patients who vomit all or part of the meal Potential complications Dizziness, tremors, anxiety, sweating, euphoria, or fainting Interfering factors Increasing factors: smoking, eating, stress, exercise Fasting or reduced caloric intake before test can cause intolerance Drugs that cause intolerance: antihypertensives, antiinflammatories, aspirin, beta blockers, furosemide, nicotine, oral contraceptives, phenothiazines, psychiatric drugs, steroids, and thiazides

8 Glycosylated hemoglobin (280-282)
Used to monitor diabetes treatment because it provides accurate long-term index of patient’s average glucose index Test explanation: Glycosylation of hemoglobin A A1c combines the most with glucose The amount of GHb (glycohemoglobin) depends on the most of glucose available in the bloodstream This shows an average glucose concentration over days Usually the degree of glucose elevation results not from a transient high level but from persistent elevation Does not need to be drawn at a specific time Serum glycalated proteins (a different test) shows a more recent evaluation of elevated blood glucose because the are degraded faster than RBC

9 Glycosylated hemoglobin (280-282) cont.
Test explanation Good for determining: Evaluation of the success of diabetic treatment and patient compliance Comparing and contrasting the success of past and new forms of diabetic therapy Determining duration of hyperglycemia Providing sensitive estimate of glucose imbalance in patients with mild diabetes Individualizing diabetic control Providing a sense of reward for many patients Evaluating the diabetic patient whose glucose levels change significantly from day to day (brittle diabetes) Mean plasma glucose = (35.6 x GHb) – 77.3 Interfering factors Hemoglobinopathies affect results because quantity of hemoglobin A varies False elevation: when RBC life span is lengthened because the HBA1 has longer period for glycosylation Abnormal low levels of proteins may falsely indicate normal glycalated fructosamine levels despite reality of high glucose Ascorbic acid may cause false lows

10 Vitamin B12 ( ) Identify the cause of megoblastic anemia and evaluate malnourished patients Test explanation: B12 is needed for the conversion of folate to the active form Necessary for synthesis of nucleic acids and amino acids Most notable in the formation of RBC RBC are megoblastic in B12 deficiency so they cannot conform to the size of small capillaries RBC fracture and hemolyze causing shortened life span Giant, segmented neutrophils and large nucleated platelets are also seen May take 6-8 months (of absence of B12) to be seen Meat, eggs, and dairy are main source of B12 Intrinsic factor is needed for B12 absorption (pernicious anemia) Gastric acid separates B12 from its binding protein Malabsorption also causes decrease More prolonged deficiency is best measured by MMA (urinary methylmalonic acid) Elevated serum MMA and urinary excretion of MMA measure B12 activity The active form of B12 converts L-methylmalonyl CoA to succinyl CoA so without active B 12 larger quantities of MMA is seen in urine Urine MMA test is more accurate Mass spect measures MMA in urine Interfering factors Chloral hydrate increases B12 Drugs that decrease: alcohol, aminoglycosidesm aminosalicylic acid, anticonvulsants, colchicine, oral contraceptives

11 Electroneurography (581-582)
Normal findings show no peripheral nerve injury or disease Identifies peripheral nerve injury in patients with localized or diffuse weakness, to differentiate primary peripheral nerve disease from muscular injury, and to document the severity of injury in legal cases Monitors nerve injury and response to treatment Criteria for brain death Absence of hypothermia (meaning only determined if core temp has been restored) Absence of neuromuscular blockade administration Absence of possibility of drug or metabolic induced coma Absence of response to painful stimuli or other noxious stimuli Cerebral flow studies show no blood flow to brain Isoelectric EEG No attempt at respiration with PCO2 > 500 mmHg Fixed pupils No corneal reflexes

12 Electroneurography (581-582) Cont.
Test explanation: Allows the detection and location of peripheral nerve injury or disease Initiate an electrical impulse at one site (proximal) of a nerve and record the time required for that impulse to travel to a second site (distal) of the same nerve The conduction velocity can be determined Done in conjunction with EMG (Electromyography = skeletal muscle eval) Normal values vary from nerve to nerve and among individuals Compare conduction velocity of the suspected side with the contralateral nerve conduction velocity Normal conduction velocity is m/sec Traumatic transection or contusion of a nerve will usually cause maximal slowing of conduction Neuropathies, both local and general, cause slowing Greater than normal values are not pathologic Primary muscle disorders can cause a slow conduction because conduction may require muscle contraction Muscular factor can be evaluated by measuring latency (time required for stimulation of distal end to cause muscular contraction) Conduction velocity = (distance (m))/ (total latency – distal latency) Interfering factors Patients in severe pain

13 Urine glucose (969-970) Part of a routine urinalysis
If present, reflects degree of glucose elevation in blood Monitors the effectiveness of therapy for DM Test explanation May indicate DM or other glucose intolerance disorders Normally blood glucose is filtered from blood by glomeruli and all the glucose is reabsorbed in proximal tubules Blood glucose exceeds capability of renal threshold to reabsorb and it spills into the urine Glucosuria may occur immediately after a high carb meal or in patients on IV dextrose or due to stress or injury Glucosuria can indicate diseases that affect renal tubule or genetic defects in metabolism and excretion of glucose In these disorders renal threshold for glucose is low so normal blood glucose cannot be reabsorbed GT test in these patients are usually normal Interfering factors Sugars can cause false positive Drugs that cause false positive: ASA, aminosalicylic acid, ascorbic acid, cephalothin, chloral hydrate, nitrofurantoin, streptomycin, and sulfonamides False negative: ascorbic acid (clinistix test), levodopa, and phenazopyridine Drugs that increase urine glucose: ASA, cephalosporins, chloral hydrate, chloramphenicol, dextrothyroxine, diazoxide, diuretics, estrogen, glucose infusions, isoniazid, levedopa, lithium, nafcillin, nalidixic acid, and nicotinic acid

14 Drugs to know

15 Therapeutic considerations
Drug Uses Side effects Contraindications Therapeutic considerations Alendronate Class: Bisphosphonate Mech: Decreases bone reabsorption by osteoclasts; blocks a step in the mevalonate pathway Indications: Osteoporosis prevention and treatment Paget’s disease Jaw osteonecrosis in cancer patients Cessation of bone remodeling Gastroesophageal pain Delayed gastric emptying Inability to sit up for 30 minutes after taking drug hypocalcemia Extended skeletal effects, unclear how to define overdose IV dose corrects hypercalcemia in days all secreted by kidney Calcitonin (Salmon) Mech: binds to and activates a G-protein coupled receptor on osteoclasts to decrease resorptive activity Hypercalcemia Postmenopausal osteoporosis Flushing Nausea Diarrhea Tachyphylaxis Hypersensitivity Nasal spray or subcutaneous Subcutaneous lowers blood calcium over hours Raloxifene Class: Selective estrogen receptor modulator (SERMs) Mech: Estrogen receptor agonist in bone, estrogen receptor antagonist against endometrium and breast Indication: Retinal vascular occlusion Venous thromboembolism Pulmonary embolism Hot flashes Leg cramps Pregnancy History or presence of venous thromboembolism Decreases breast cancer incidence

16 Insulin Drug Uses Side effects Contraindications
Therapeutic considerations Metformin Class: Insulin sensitizing - biguanides Mech: Activates AMP dependent protein kinase to block synthesis of fatty acids and to inhibit hepatic gluconeogenesis and glycogenolysis; increases insulin receptor activity and metabolic responsiveness of liver and skeletal muscle Indications: Type 2 diabetes Polycystic ovarian syndrome Lactic acidosis GI distress: diarrhea, dyspepsia, flatulence, nausea, vomiting, cobalamin deficiency Heart failure* Septicemia Alcohol abuse* Hepatic disease* Respiratory disease* Renal impairment* Iodinated contrast material if acute alteration of renal function is suspected which may further lactic acidosis Metabolic acidosis GI distress associated with metformin is usually transient and can be minimized by slow titration of dose Incidence of lactic acidosis is low and predictable; lactic acidosis typically occurs with metformin use in patients who have other conditions that predispose to metabolic acidosis Does not induce hypoglycemia Lowers serum lipids and decreases weight Insulin (Prandial bolus or Basal “long acting” insulins) Class: exogenous insulin Mech: Promotes carb metabolism and facilitates glucose, amino acid, and Tg uptake and storage in liver, cardiac and skeletal muscle, and adipose tissue Indication: Diabetes mellitus Hypglycemia Injection site reaction Lipodystrophy Hypoglycemia Not orally available, subcutaneous route Rapid acting analogues lispro, aspart, and glulisine offer flexibility and convenience Regular insulin is short acting must be give 30 minutes before meal NPH is intermediate acting contains protamine which prolongs time required for absorption Insulin glargine and detemir are long acting steady release without peak Hypoglycemia is a major danger especially without carb intake

17 Drug Uses Side effects Contraindications Therapeutic considerations Enalapril Class: ACE Inhibitors Mech: Decreases conversion of angiotensin (AT) I to AT II, which decreases vasoconstriction of arterioles, aldosterone synthesis, renal proximal tubule NaCl reabsorption, and ADH release; also inhibit degradation of bradykinin, which increases vasodilation Indications: Hypertension heart failure diabetic nephropathy MI Angioedema (more frequent in black patients) Agranulocytosis Neutropenia Cough, Edema Hypotension Rash Gynecomastia Hyperkalemia Proteinuria History of angioedema Bilateral renal artery stenosis Renal failure Pregnancy Ester prodrug activated in plasma Bradykinin causes cough and edema; angioedema can be potentially life-threatening Delays progression of cardiac contractile dysfunction in HF and after MI; delay diabetic neuropathy Co-admin with allopurinol may predispose to hypersensitivity rxn including Steven Johnson syndrome Lisinopril Same as above Amlodipine (Dihydropyridine) Class: Calcium channel blocker Mech: Another calcium channel blocker Indication: Exertional angina Unstable angina Coronary spasm Hypertrophic cardiomyopathy Pre-eclampsia Increased angina, Rare MI Palpitations Peripheral edema Flushing Constipation Heartburn Dizziness Preexisting hypotension Arteriolar dilation greater than venous High vascular to cardiac selectivity Less depression of myocardial contractility, minimal effects on nodal conduction Higher bioavailability, longer time to peak plasma concentration, and slower hepatic metabolism

18 Therapeutic considerations
Drug Uses Side effects Contraindications Therapeutic considerations Cisplatin Class: Directly modify DNA structure Mech: Platinum compound that cross-links intrastrand guanine bases Indications: Genitourinary and 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 Ezetimibe Class: Inhibitors of cholesterol absorption Mech: Decreases cholesterol transport from micelles into enterocyte inhibiting NPC1L1 Primary hypercholesterolemia Familial hypercholesterolemia Sitosterolemia Elevated liver function tests Myopathy Dyspepsia Arthralgia Myalgia Headache Active liver disease Persistently elevated liver function tests when co-administered with statin Modest LDL reduction, small effect on HDL and Tgs Inhibition of hepatic cholesterol absorption causes compensatory increases in synthesis partially off setting; prevented by giving statin Rapidly absorbed Levels are increased by cyclosporines and fibrates Vincristine Class: Inhibit microtubule polymerization Mech: Binds tubulin subunits and prevents microtubule polymerization Leukemia Hodgkin’s disease Non-hodgkins lymphoma Rhadomyosarcoma Nephroblastoma Alopecia GI disturbances Diplopia Charcot-Marie Tooth syndrome Intrathecal use Peripheral neuropathy is dose limiting

19 Therapeutic considerations Dexamethasone
Drug Uses Side effects Contraindications Therapeutic considerations Dexamethasone Class: Glucocorticoid receptor agonist Mech: Mimic cortisol function by acting as agonists at glucocorticoid receptor Indications: Inflammatory conditions in many different organs Autoimmune diseases Immunosupression Cataracts Hyperglycemia Hypercortisolism Depression Euphoria Osteoporosis Growth retardation in kids Muscle atrophy Impaired wound healing Hypertension Fluid retention Inhaled may cause oropharyngeal candidiasis and dysphonia Topical causes skin atrophy Systemic fungal infection Doesn’t correct underlying etiology just limits inflammation Should be tapered when given chronically to avoid withdrawal and acute adrenal insufficiency Intranasal and inhaled greatly reduce systemic adverse effects Hydrocortisone Same as above Replacement therapy for primary and secondary adrenal insufficiency Verapamil (Phenylalkylamine) Class: Calcium channel blocker Mech: block voltage-gated L-type calcium channels & prevent influx of calcium that promotes actin-myosin cross-bridge formation Prinzmetal or variant angina or chronic stable angina A fib or flutter, paroxysmal SVT Rare cardiac arrhythmia AV block Bradyarrhythmia Exacerbation of heart failure Peripheral edema Syncope Gingival hyperplasia Dizziness IV is contraindicated in patients with ventricular tachycardia and patients receiving IV beta blockers Sick sinus syndrome or 2nd or 3rd AV block SVT associated with bypass tract Left ventricular failure Hypotension Acute MI Low ratio of vascular to cardiac selectivity Depresses both SA and AV node conduction velocity Raises serum carbamazepine levels which may cause toxicity Avoid using with beta blockers Greater suppressive effect on cardiac contractility

20 Drug Uses Side effects Contraindications Therapeutic considerations Glyburide Class: Insulin secretagogues; sulfonylureas and meglitinides Mech: Inhibit the beta K+/ATP channel at SUR1 subunit stimulating insulin release from beta cells Indication: Type 2 diabetes mellitus Hypoglycemia Rash Diarrhea Nausea Dizziness Diabetic ketoacidosis Major adverse effect is hypoglycemia from too much insulin Can cause weight gain secondary to increased insulin activity in adipose tissue – better for non obese people Mainstay treatment for type II diabetes Orally available and metabolized by the liver Ocreotide Class: Somatostatin analogue Mech: Inhibits GH release Indications: Acromegaly Flushing and diarrhea from carcinoid tumors Carcinoid crisis Diarrhea from vasoactive intestinal peptide secreting tumors TSH producing adenomas Esophageal varicies Arrthymias Bradycardia Hypoglycermia Gallstone formation Abdominal pain Constipation Vomiting Hypersensitivity Used to control GI bleeding and reduces secretory diarrhea Available in monthly depot formulation longer half life than somatostatin Lomustine Lomustine is used to treat certain types of brain tumors. Lomustine is also used with other medications to treat Hodgkin's lymphoma (Hodgkin's disease) that has not improved or that has worsened after treatment with other medications. Lomustine is in a class of medications called alkylating agents. It works by slowing or stopping the growth of cancer cells in your body. Nausea, vomiting, loss of appetite, sores in the mouth and throat tiredness or weakness, pale skin Fainting, hair loss, unsteady walk, slurred speech, difficulty breathing, shortness of breath, dry cough, wheezing, decreased urination; swelling of the face, arms, hands, feet, ankles, or lower legs. yellowing or eyes and skin Confusion sudden change or loss of vision Hypersensitivity, pregnancy breast feeding Taken orally Wear gloves so skin doesn’t contact drug

21 Bates

22 Abnormalities in rate and rhythm of breathing (134)

23 Pupils and extraocular muscles (215-218)
Miosis is pupillary constriction, mydriosis is dilation Inspect size, shape and symmetry of pupils (3-5 mm) Anisocoria is pupillary inequality of less than 0.5 mm, benign if reactivity is normal (20% of normal people, these values are slightly different from the cranial nerve section) Test reaction to light: direct (constriction in the same eye) consensual (constriction in opposite eye) If reaction is impaired test near reaction in normal room light testing one eye at a time Hold pencil 10 cm and alternate having the patient look at it then at a distant object, monitor constriction with near effort From 2 feet away test reflection of light in the cornea to test for deviation. Should be visible slightly nasal to the center of the pupil cover- uncover test may reveal slight or latent muscle imbalance Nystagmus is a fine rhythmic oscillation of the eyes; seen with neurologic conditions, if seen bring finger into binocular field of vision and look again Lid lag as eyes move up to down Move finger in the ‘H’ pattern to test EOM Lr6So4Ao3 (Pause during lateral gaze to test for nystagmus) Test for convergence as well by asking patient to follow finger, light, object as you bring it toward them Hyperthyroidism shows poor convergences and proptosis with lid lag

24 Pupillary abnormalities (259)

25 Dysconjugate gaze (260)

26 The cranial nerves ( ) CN I olfactory: test smell by presenting patient with smells Smoking, parkinson’s, head trauma, aging, cocaine can eliminate sense Compress each nasal passage to test separately Have patient close eyes Avoid using noxious triggers as sample smells because this will stimulate CN V CN II optic Papilledema, disc pallor in atrophy by inspecting optic fundi Bitemporal hemianopsia from defects in optic chiasm Hemonymous hemianopsia means loss of peripheral vision seen with parietal lobe; findings of a stroke CN III oculomotor: Inspect size and shape of pupil - Anisocoria is a difference between pupils > 0.4mm, seen in 38% of normal individuals. Test reaction to light Check near response (Tests pupillary constriction, convergence and accommodation of the lens) Horners may lead to miosis = small pupil. CN III, IV, VI Occulomotor, Trochlear, Abducens Lr6So4Ao3 Test extraocular muscles in the six cardinal directions of gaze Diplopia means double vision binocular (M. gravis, trauma, thyroid opthalmopathy, internuclear opthalmoplegia) monocular ( glasses or contact problems, cataracts, astigmatism, ptosis) Check for convergence Nystagmus [ an involuntary jerking movement of the eyes with quick and slow components] seen in cerebellar disease with gait ataxia and dysarthria, vestibular disorders, internuclear othalmoplegia Ptosis is 3rd nerve palsy in horners and m. gravis

27 The cranial nerves (672-678) CN V Trigeminal CN VII Facial CN VIII
Motor: difficulty clenching the jaw or moving it to the opposite side in masseter and lateral pterygoid weakness Palpate temporal and masseter muscles and ask patient to clench teeth, move jaw side to side Bilateral weakness is cerebral hemisphere disease In stroke it’s ipsilateral face and contralateral body Sensory Test forehead, jaw and cheeks for pain sensation with patient’s eyes closed If you find an abnormality test it for temperature sensation Light touch sense with a wisp of cotton Corneal reflex Ask patient to look up and away from you approach other side lightly touch with a fine wisp of cotton ( Make sure you are touching the cornea not the conjuctiva) Absent blinking is CN V lesion CN VII Facial Look at face at rest and during conversation notice any asymmetry Drooping of eyelid and flattening of nasolabial fold Bell’s palsy affects both sides of lower face Patient should raise eyebrows, frown, close both eyes tightly, show upper and lower teeth, smile, puff out both cheeks CN VIII Assess hearing with whispered voice Conductive (air through ear) or sensorineural from cochlear CN VIII damage Rinne test for air and bone conduction Lateralization using weber test

28 The cranial nerves (672-678) IX and X Glossopharyngeal and Vagus
Hoarseness in voice, vocal cord paralysis Nasal voice in palate paralysis Pharyngeal or palate weakness Difficulty swallowing Have patient say “Ah” and watch the movement of soft palate and pharynx Deviation of uvula points to X damage Palate fails to rise in vagus injury, uvula pulled away from lesion Stick out tongue and test gag reflex ( elevation of tongue and soft palate and constriction of pharyngeal muscles) XI spinal accessory Trapezius weakness with fasciculations shoulder droops and scapula is displaced downward and laterally Fasciculations are fine flickering irregular movements of small groups of muscle fibers Patient shrugs both shoulders against resistance Turn head to each side against your hand, testing opposite side SCM XII hypoglossal Poor word articulation or dysarthria may mean tongue atrophy and fasciculations in amyotrophic lateral sclerosis, polio Have patient protrude tongue looking for asymmetry, atrophy or deviation Have patient move tongue from side to side Have patient push tongue against cheek, and dr pushes on it externally to palpate for strength Lick your wounds in unilateral cortical lesion

29 Exam of tympanic membrane (813-814)
In kids pull auricle upward, outward and backward Tips: use best angle of otoscope, use largest possible speculum, don’t apply too much pressure, insert speculum ¼-1/2 inch into canal, note whether tympanic membrane is abnormal, remove cerumen if blocking view using plastic curettes, moistened microtipped cotton swab, flushing of ears Hold the lateral aspect of your hand that has the otoscope against the child’s head to buffer against sudden movements Or, hold handle facing downward at feet and hold head with other hand Otitis media shows red, bulging tympanic membrane with dull or absent light reflex, purulent matter may be seen Pneumatic otoscope improves accuracy assess mobility of tympanic membrane (mobility is absent in effusion, can have temporal hearing loss) When air is removed the Tympanic Membrane moves towards you. When air is added its light reflex moves inwards. Otitis externa: movement of pinna causes pain Mastoiditis: auricle protrudes forward area over mastoid is swollen

30 Babinski and Brudzinski signs (701-703)
Dorsiflexion of the big toe is a positive babinski response from a CNS lesion in corticospinal tract (upper motor neuron) May also been seen in unconscious states from drug or alcohol intoxication or postictal period following a seizure Can be accompanied by reflex flexion of hip and knee Preformed by stroking from the lateral aspect of the sole from the heat to the ball of the foot, curving medially across the ball. Normal (NEGATIVE babinski) big toe will plantar flex Brudzinski As you flex the neck, watch the hips and knees in reaction to your maneuver. Normally they should remain relaxed and motionless Flexion of the knees and the hips is a positive Brudzinski sign and suggests meningeal inflammation

31 Radiology 101

32 Radiography, CT, and MRI (2-11)
Common views are posterioranterior, anteriorposterior, oblique, and lateral PA means beams travel back to front Lateral means side to side AP is sitting, upright or supine Density determines how much beam will be absorbed Air and fat black, water gray, bone or metal white Muscles, organs, or soft tissue appear different shades of gray depending on water density Radiographic screens are on bold sides of the film and they emit light flashes and fluoresce which becomes the exposure Digital or computed radiography Producing a digital image by scanning the phosphor plate with a laser beam that causes light to be released from phosphor plate The intensity of emitted light depends on local radiation exposure A photomultiplier tube amplifies the light and converts it into an electron stream, the electron stream is digitized and then converted into an image

33 Radiography, CT, and MRI (2-11) cont.
Contrast media Using pharmaceuticals to differentiate between normal and abnormal tissues, to define vascular anatomy, and to improve visualization of some organs Iodine molecules bound to chemicals that absorb varying degrees of x-ray absorption More uptake of contrast = enhancement With the high osmolar contrast there were reactions of vomiting, pain at injection site, respiratory symptoms, urticaria, and generalized burning Low osmolar contrast agents have replaced high ones and improve comfort but there is still a risk of nephropathy Arthography: inject contrast media or air into a joint Myelography: places it in spinal subarachnoid space usually with lumbar puncture diagnosing diseases around cord Orally ingested tablets are metabolized by liver and concentrated in gall bladder providing information about function, calculi, and tumors Barium used for GI usually with air to provide double contrast, but if perf or serious damage suspected use water based MRI uses gadolinium or other metals with unpaired electrons it changes T1 useful in imaging tumors, infections and acute cerebral vascular accidents, can cause NSF (nephrogenic sclerosing fibrosis) if patient on dialysis or has creatinine clearance less that 30 mg/dL

34 CT Sagittal, coronal, and axial
Originally created exclusively for brain Looking at slices of a loaf of bread 1-10 mm slices. Usually 10mm cuts for lung because of large tissue X ray beams pass through and eventually meet detectors Intracerebral hemorrhage or fracture: contrast not needed Contrast increases density of blood vessels, vascular soft tissue, organs and tumors High resolution uses thinner slices 1-2 mm Useful in parenchymal lung disease Helical or spiral patient continuously moves while beams encircle the patient improving images in thorax and abdomen Multislice/dynamic: multiple detectors that yield multiple tomographic slices

35 MRI Coronal and sagittal
Small changes within contrast and MRI soft tissue Exposure to magnetic fields and radio frequency waves Not recommended during first trimester Bad for those with claustrophobia and loud Imaging of protons (hydrogen) which have a spin frequency Compares spin frequency Short bursts of radio-frequency waves are broadcast and protons absorb wave energy and become energized or resonate The intensity of radio wave signal detected by coil determines number and locations of resonating hydrogen Many in fat so it will be bright, less in bone If radio receivers listen early in the decay following discontinuance of radio wave broadcast it is T1 weighted where fat is white and gray soft tissue detail is excellent, good for anatomy Late listening is water in soft tissue a lighter gray and fat is gray is T2; better for pathology Angiography: image vessels without catheters, iodine blood appears bright fMRI: identifying activity by oxygenated and deoxygenated blood Can be used for heart too Infarcted areas appear white Diffusion weighted Ischemic stroke Abnormal motion is detected Spectroscopy Assessing protons in acetyl aspartate, choline, creatinine, and lactate Evaluate cancerous lesions since they have increased choline and reduced NAA Stroke has increased lactate Disorders of metabolism

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