Asthma drugs made EZ

Pharmacology is often considered a dirty word in nursing and medical school, and unfortunately the NCLEX and the USMLE loves to test you on this. One subject we recently tackled in our NCLEX review course was the treatment of Asthma. Here is a summary of what we talked about...


Obstructive Pulmonary Disease (Asthma, COPD)•Medications: Site of Action
1.Adrenergic Agonists (Albuterol, etc)
2.Anticholinergics (Ipratroprium Bromide)
3.Xanthines (Theophylline)
4.Corticosteroids (Beclomethasone, etc)
5.Mast Cell Stabilizers (Cromolyn)
6.Leukotriene Antagonists (Montelukast-Singulair)


key to above figure: Allergen+IGE causes Mast cell to release histamine and leukotrienes which then seep out of blood stream and cause immune cells to inflame bronchioles. Various drugs work at different steps of this process. Some stop mast cells from releasing their products, some stop the products from leaving the blood stream, and some stop the products from causing the inflammation in the bronchioles. All three of these work directly on the immune system. On the other side of that, some drugs directly open the airway, not effecting the immunity at all. See below for the most critical details on these drugs and when we use them...

Obstructive Pulmonary Disease: Bronchodilators
1.Adrenergic Agonists (Albuterol, etc)
•Selective B2 agonists directly dilate airway; DOC for acute attack
•Albuterol: PO, inhaled via MDI; NOT for maintenance therapy
•Levalbuterol (Xopenex): Possibly less cardiac SE
•Salmeterol: Long acting (12hrs) for night s/s
•Terbutaline: Also relaxes uterus, tocolytic for premature labor

2.Anticholinergics (Ipratroprium Bromide) *technically not a dilator
•Atrovent is often combined with Adrenergics to tx COPD, as scarred airways need extra help dilating
•Slow onset, long acting best used for prevention, not acutely
•SE: Dry mouth, GI distress

3.Xanthines (Theophylline)
•Similar to Caffeine, causes bronchodilation, CNS stimulation of the respiratory center, Inotropy/chronotropy → renal perfusion → urine
•Used in cases where overuse of other bronchodilators has caused decreased effectiveness, especially used with COPD
•Slow onset, long acting best used for prevention, not acutely
•Stimulant C/I with arrhythmias, SZ, hyperthyroid, PUD
•Monitor therapeutic levels (10-20)
•Aminophylline is IV form of Theophylline

Obstructive Pulmonary Disease: Inflammation Modulators
1.Corticosteroids (Beclomethasone, etc)
•Steroids prevent further inflammation of constricted airways
•Available IV, PO or inhaled; Inhaled have benefit of being used at site of constriction without systemic effects (Rinse after!)
•DOC for asthma prevention•Beclomethasone excellent antiinflammatory with few SE
•Patients have died from not being tapered off of systemic steroids when switching to inhaled forms
•Can be used WITH albuterol for acute attacks and is given IV (Solu-Medrol)

2.Mast Cell Stabilizers (Cromolyn)
•Used to prevent the release of inflammatory mediators
•Most effective for exercise or allergen induced bronchospasm
•Also useful to control perennial allergic rhinitis
•Available PO, inhaled, and opthalmic

3.Leukotriene Antagonists (Montelukast-Singulair)
•Leukotriene receptor blockade prevents inflammatory migration into bronchiole tissue
•Used for maintenance, with effects taking up to a week
•SE: Dyspepsia, insomnia, diarrhea, and liver dysfunction
•Other ex. Zafirlukast (Accolate), Zileuton (Zyflo)

Asthma Treatment Protocol (med first introduced)

• Step 1, Mild Intermittent S/S: Short acting B2 agonists prn
• Step 2, Mild Persistent: Inh steroid + short B2 ag prn; Cromolyn + B2 ag prn for children; Theophylline or Montelukast alternative agents if above protocol ineffective
• Step 3, Moderate Persistent: Med dose inh steroid + Salmeterol (long acting B2) + short B2ag prn
• Step 4, Severe Persistent: High dose inh steroid + Salmeterol + Systemic steroid + short B2 ag prn

Diagnostic Tests made EZ

I remember trying to answer questions about the care of patients before, during and after certain diagnositic tests, and having no clue, mainly because I didn't really know what the test really was. So I am posting some pictures with a common point or two related to that test, that the NCLEX and the USMLE frequently asks. Hope you find this makes it a bit EZer to grasp.


Bronchoscopy (BAL)

• Definitive diagnosis of TB


• Lidocaine used intraoperatively to numb gag and cough receptors so assure patient has gag reflex back before feeding or giving fluids

Chest Xray

• Xray can be used for multiple diseases, and can be focused on chest, abdomen, cervical spine, extremeties, etc


• Portable xrays are frequently used for many respiratory complaints so prepare to see this ordered when you pass the boards and become an RN


• In any female inquire if there is any possibility they are pregnant, as xray is contraindicated if so


• Remove jewelry as will show up on xray and cover possible results
  
  

Thoracentesis

• In this procedure, a needle is inserted into the pleural space (membrane surrounding lungs) to draw out fluid


• May be a one time withdrawal, or may leave a drain in place


• Used for Pleural Effusions, Empyema, etc.


• Patient often placed on affected side, to allow good lung freedom to breathe


• Cardiocentesis, is similar procedure used for fluid around heart (Tamponade)

Pulmonary Angiography

• Definitive test used as gold standard diagnosis of Pulmonary Embolism


• Contrast material is inserted via a catheter, directly into lung vasculature (often entered through Femoral vein) and the flow of contrast is seen under fluoroscopy


• Expensive and time to test is often greater than desired, so CT or VQ scan often replace for PE


• Contrast material is used, so caution for allergies or kidney failure. As a general rule patients should receive more than normal fluids for 24 hours after contrast to help flush it ouf of system.

Arterial Blood Gas

• ABGs are often requested when acute respiratory or metabolic issues are occuring


• You may be on a unit very soon that will require you to perform this task


• Remember to do an Allen Test first (occlude radial/ulnar arteries, and release one then the other observing return of blood flow to hand in between)


• Do not suggest if your plan of care would not change with result possibilities


• When analyzing ABGs, look at pH first! High is alkalosis, low is acidosis. Then simply see if bicarb or CO2 has changed to determine what type is present (bicarb is metabolic, CO2 is respiratory)
  
  

Circular CT

• The most common type of test used for diagnosing Pulmonary Embolism, as well as a host of other diseases. This test produces picture slices through the body, like you were sliced in half.


• Contrast is usually used for circular CT, and can be seen in picture above as white material. Large circle on bottom of picture is the Aorta, and the smaller circles to the right are pulmonary arteries. Notice the dark circle in middle that resembles a donut? That is an embolus in the lung (PE)


• Remember all issues with contrast (allergies, kidney failure, patient on Metformin?)


• See pic below for what a circular CT looks like
  
  
  

MRI (magnetic resonance imaging)

• Similar results to a CT, but much prettier pictures. Due to the improved clarity are becoming gold standard for many diseases


• But test can take hours to perform, so not the best choice for rapidly deteriorating conditions.


• Since the test uses magnets, the patient can not have metallic heart valves or cochlear implants


• Contrast may also be used


• See below for image obtained by MRI, noticing the various slices we are able to obtain and use

CT (computerized tomagraphy)

• While the picture may not be as clear as an MRI, these images are actually better at seeing fluids, such as blood, and thus are usually first line for possible hemorrhagic strokes and other diseases


• Notice in picture above, to the right, contrast has been used which allows certain areas to become much brighter. In these pictures, the large tumor on the right is enhanced by contrast.


• All of the issues of contrast must be considered however


• See below for pic of CT,,,again

Lumbar Puncture


LP Indications
• Diagnosis of Meningitis
• Diagnosis of Subarachnoid bleed
• Diagnosis of Multiple Sclerosis
• Diagnosis of Malignancy
• Introduction of contrast or anesthetics

• LPs are taken with patient in fetal position (on side, legs drawn up, head on chest)
• Be on the alert for severe headache post procedure from drawing too much CSF out

Myelogram

• In this procedure, an LP is performed, and dye is injected under fluoroscopy.
• Xrays are then taken to measure flow of CSF and look for constrictions
• Dye may be oil or water based
• If an oil-based dye was used, the patient is kept flat in bed for approximately 8 hours
• If a water-soluble dye was used, bed rest is maintained, with the head of the bed elevated 30 degrees for 6 to 8 hours

OK...hope that helped a bit with getting a picture of certain diagnostics you will run across commonly in the hospital or on the NCLEX. Good luck!

TB made EZ

Tuberculosis is one of the world's most beatable disease, yet remains one of the biggest killers. It also can be a killer on the NCLEX or USMLE, as these tests commonly have questions related to this infectious disease. Common subjects include the diagnostic tests and antibacterial drugs used in treatment. Lets take a quick look at this subject, and see if we can make TB EZ.

Tuberculosis

•Most common cause of death due to infection worldwide
•Bacteria are unique for their ability to form granulomas in oxygen rich areas of lungs (often the apices due to the higher O2 levels) to protect themselves from elimination
•May stay dormant for years, becoming active w/any insult to immunity
•Spread by droplets (droplet precaution taken) and only contagious when active
•S/S: Fever, night sweats, weight loss, malaise, and hemoptysis (bloody cough)
•DX:

1. • PPD: (+) if above or = 10cm in at risk or above or = 5cm in HIV, transplant, contacts (indicates exposure); The only patients that are + with above 15mm are those that shouldn't have been tested (no risk); Send for CXR if (+)
2. • CXR: (-) take INH 9 mos; Send for BAL if (+) CXR (indicates previous infection)
3. • BAL: (-) take INH 9 mos; (+) start 4 drug treatment protocol as resistance severe with Mycobacterium (indicates active infection)

•Treatment Protocol: (with most common side/adverse effect)

• Drug susceptibility test should be performed initially with culture

1. Isoniazid (INH): Hepatotoxicity
2. Rifampin: Red urine/tears/sputum/sweat
3. Pyrazinamide (PZD): Uricemia/Stones in P
4. Ethambutol: Blindness in Eyes (OR) Streptomycin: Ototoxic, Nephrotoxic

•Length of treatment can be long (up to 2 years) so patient compliance is a HUGE issue and number one cause of Antibiotic resistance present today.
•Stress to patient the fact that compliance to full regime has more than 90% cure rates, but must take meds everyday at same time!

PPD: Measure induration (redness) not just swollen area to detect if exposure has occurred.
Bottom picture shows Chest Xray with Granulomas (cavities) caused by previous TB infection


BAL: Bronchoalveolar lavage or bronchoscopy is the ONLY way of truly diagnosing TB. Think of Bigfoot...no matter how many pictures we have seen of someone that supposedly saw bigfoot, the only way to prove he exists is to capture him. Same way for infectious disease...the only truly positive diagnosis is to capture the bugs and grow them on a culture plate. So don't let them trick you on the test by saying a Positive ppd or chest xray means the patient has TB. Only then do we treat them with the 4 drug combo.

Renal Patho made EZ

Ahh the kidneys. Quite a complicated subject, but one that is very fascinating if you really understand it. Before you really dive into those NCLEX or USMLE Review books, check this out...

Lets take the Nephron apart and look at some of the components...

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Proximal Convoluted Tubule
• Approximately 2/3 of the filtered water and Na are reabsorbed into the blood in the PCT
• All Glucose (up to 300 level in blood) is reabsorbed in the PCT, as are some BUN, Phos, Mg, Ca, etc.
• PCT plays an important role in pH balance of both blood and urine
• PCT damage is a common cause of Acute Renal Failure (ATN-discussed later)


Key to Image:
1.Because protein is concentrated in blood of efferent arteries, osmotic pressure in arteries is high and water follows
2.Na flows out of filtrate into cell, down gradient, with water following. This flow generates power that opens channels to allow other solutes to follow. An Na-K pump at the cell/artery boundary keeps intracellular Na low maintaining gradient.
3.If blood is acidic, H acumulates intracellularly and exchanges for additional Na, thereby lowering the body pH and acidifying the urine. H can also be pumped out of cell where it combines with filtered HCO3, forming H2CO3, which is excreted. One other method of lowering acid levels is to pump out NH3 from cell in addition to H, which when combined, forms NH4 and is excreted.

Loop of Henle• Approximately 20% of filtered water and Na are reabsorbed in the Loop
• Water is absorbed in the D-loop, while Na is absorbed in the A-loop
• Reabsorbed Na plays a major role in creating a gradient for descending water to leave the filtrate: the more Na reabsorbed, the more water is reabsorbed
• Reabsorbed Na also powers the reabsorption of other electrolytes by opening channels specific to their transport


Pharm Tip: Loop Diuretics (Lasix, Bumex, Ethacrinic acid) block Na reabsorption here which leads to no absorption of water or other electrolytes, and moderate diuresis. The diuresis is a bit too much for daily treatment of HT, but plays a role in the acute excretion of fluids in cases of volume overload like Congestive Heart Failure and Pulmonary edema. Since other electrolytes are excreted you must be cautious for electrolyte abnormalities such as hypokalemia and hypocalcemia.

Distal Convoluted Tubule
• Approximately 7% of Water and Na reabsorption occur in the DCT
• Na once again powers the reabsorption of Cl
• Ca excretion occurs here (in exchange for Na) under the control of Parathyroid hormone (PTH)

Pharm Tip: Thiazide diuretics (Hydrochlorothiazide: HCTZ) blocks Na reabsorption here which subsequently leads to mild diuresis. Because of reduced amount of water reabsorbed here, loss of this water through the use of thiazides carries less risk of dehydration and hypokalemia, while effectively reducing fluids enough to have decent effects on BP. For this reason, HCTZ is often the first line medication in the treatment of Hypertension.
But Thiazides, while blocking the Na channel from reabsorbing urine Na also block the excretion of Ca through that channel, which while useful in someone with Ca stones or Osteoporosis, is dangerous in someone with already high levels of Ca.
This blockage of Ca channels also means vascular smooth muscle can not contract as well leading to slight vasodilation, further enhancing their anti-hypertensive effect.


Collecting Duct•Only 5% of Na and Water reabsorption occurs here so only minor diuresis occurs with drugs that target the CD
•Important for more than just diuresis…
1.Aldosterone, released by the adrenal glands, opens Na channels which leads to some increase in water reabsorption and increased blood volume. A Na-K pump keeps intracellular Na low to maintain the gradient, as well as K high for exchange with filtrate Na.
2.When the blood is acidic, H enters cell in place of K. The blood becomes hyperkalemic, and Na now exchanges for H, which is excreted in the urine.
3.ADH, released by the pituitary, opens aquaporins in the CD, which allows reentry of free water. Alcohol stops this hormone from working.

Pharm Tip: Spironalctone and Amiloride block Na reabsorption and subsequent K excretion, which is why they are K-sparing diuretics that can lead to hyperkalemia. They are often used in combo with K-wasting diuretics to offset the K loss. Ace Inhibitors also have an effect by blocking release of Aldosterone.

The role of Albumin...made EZ

Whether you are studying for the NCLEX or the USMLE, albumin can be a difficult subject to grasp. Check this lecture piece out to hear it made EZ

Cardiac Output made EZ

A guaranteed subject that you will be tested on during your NCLEX or USMLE examination is basic physiology of the heart. It is so important that we spent 2 straight weeks on this subject at my medical school during our cardiology module. So before diving into those NCLEX and USMLE review books, check this out...

Cardiac Output

• The cardiac output (CO) is the result of the stroke volume x HR/min
• Stroke volume (SV) is never 100% of the volume in the ventricle at the end of diastole, but is usually an ejection fraction of 60-80%
• The stroke volume and subsequent CO depends upon four parameters

1. Preload (PL)• Amount of blood in the left ventricle at the end of diastole
   • It is determined by the compliance of the ventricle and the amount delivered by the venous system
   • Constriction of the venous system causes blood to be delivered faster, increasing preload
   • When preload is higher, the ventricles get stretched more: Think of a bow and arrow; the more you stretch the string, the more forceful the ejection of the arrow
   • Thus with more stretching (preload), you get a more forceful contraction, up until a critical point, when the heart is overstretched. Again think if you pull the bow and arrow string too far and it breaks; no ejection of the arrow



2. Contractility
   • The ability of the heart to contract and the force at which it does so
   • The force of contraction is determined by how much Ca is stored in the SR
   • Contractility can be increased by flooding the cell with more Ca (beta agonist) or by keeping more Ca in the SR and not letting it escape outside of the cell (Digoxin)
   • Contractility can be decreased by the opposite effect on Ca or by damage to the myocytes (myocardial infarction)


3. Afterload
   • Essentially equivalent to aortic back pressure that the heart must pump against
   • Afterload is actually controlled by the resistance in the capillaries
   • As afterload increases it takes longer for the pressure in the ventricle to become higher than aortic pressure, and only when this happens does the aortic valve open and allow blood to flow out (remember things always go from high to low pressure)
   • Therefore there is less time to expel blood during systole, so CO decreases with increased afterload


4. Heart Rate
   • Remember CO = HR x SV
   • Do the math and see that an increase in HR also increases CO
   • Increased HR also increases amount of blood in the vasculature, which stretches the arteries resulting in an increased BP
   • This increase in CO continues to a point at about 140 bpm, when diastolic filling time gets too short and SV begins to decrease, causing an eventual decrease in CO

Summary:
• Think of a bucket with a faucet filling and a pump and hose draining
• The faucet = Preload or amount filling heart
• Pump = Heart contractility
• Hose = Diameter of hose is Afterload