Surgical Pharmacology: DIURETICS – Flashcards
Unlock all answers in this set
Unlock answersquestion
What are diuretics?
answer
• Agents administered to reduce the amount of fluid accumulating in patients with renal, hepatic, or cardiac dysfunction as well as to relieve excessive intracranial or intraocular pressure. • Lowers blood pressure.
question
How are diuretics classified?
answer
By where and how they work.
question
What should you be on the look out for in regards to your patient and diuretics in the preoperative phase?
answer
• Some patients may have been on diuretics for a long time • There may be an increased risk of Hypokalemia (low potassium / K+) which would result in a cancelation of the surgery
question
Hyperkalemia
answer
• Too MUCH potassium / K+ • Can cause cardiac disarythmia
question
What can cause hyperkalemia?
answer
• Renal dysfunction such as the kidneys' inability to excrete excess amounts of K+ • When there is a decreased urine output • Renal failure.
question
Hypokalemia
answer
• Too LITTLE potassium / K+ • Can cause cardiac disarythmia
question
What can cause hypokalemia?
answer
• Excess vomiting and diarrhea • Severe trauma such as burns • Chronic renal disease • Excessive doses of cortisone • Long-term diuretic therapy for chronic conditions such as hypertension (high blood pressure)
question
How is minor hypokalemia treated?
answer
By replacing K+ with diet or an oral supplement .
question
How is severe hypokalemia treated?
answer
• Intravenous administration of K+ such as potassium chloride as an inpatient • Cardiac monitoring
question
Why would you be administered a diuretic in the intraoperative phase of surgery?
answer
To rapidly or temporarily lower body fluids. ie. craniotomy to prevent brain swelling, vascular surgery to keep fluid flowing through the kidneys
question
Who administers diuretics during surgery?
answer
The anesthesiologist
question
How are diuretics administered during surgery?
answer
Intravenously
question
What is the function of diuretics?
answer
• To prevent reabsorption of sodium and water by the kidney. • Causes excretion of large amounts of dilute urine. • Used to treat a number of fluid disorders.
question
What is the primary function of the kidney?
answer
To maintain homeostasis by • filtering blood and • removing water and solutes (K+ and Na+)
question
What is a nephron?
answer
A microscopic filtering unit in the kidney.
question
How does blood enter the nephron?
answer
Via the afferent arteriole.
question
What is the purpose of Bowman's capsule?
answer
To filter fluid and solutes through it's membrane.
question
How does blood exit the nephron?
answer
Via the efferent arteriole.
question
Where in the nephron is water and other needed substances reabsorbed?
answer
In the proximal convoluted tubule and the Loop of Henle.
question
What are some disease that require the use of diuretics?
answer
• Congestive Heart Failure (CHF): most common • Glaucoma: the increase of pressure within the eyeball (intraocular pressure) • Liver Failure • Kidney Failure • Generalized Edema: fluid accumulation that affects the whole body
question
What type of patient could you expect to be on long-term diuretic therapy?
answer
• Patients with chronic disease such as CHF • Hip fracture patients • Patients scheduled for vascular procedures • Elderly / geriatric patients
question
What is the impact of long-term diuretic therapy?
answer
• Lowers potassium (K+) levels = cardiac irritability • Cardiac irritability + anesthesia = increased risk of cardiac arrest and muscle weakness
question
How can long-term diuretic therapy affect a scheduled surgery?
answer
• It may delay or force rescheduling of the surgery. • K+ levels must be verified prior to opening the sterile field.
question
What is the normal range for potassium (K+) levels?
answer
3.5 to 5.0 mEq/L
question
What is the purpose of long-term diuretics?
answer
Chronic fluid management
question
What is the purpose short-term diuretics?
answer
• To decrease intraoperative swelling • To decrease postoperative swelling
question
What do short-term intraoperative diuretics require?
answer
• The insertion of an indwelling urinary catheter in the patient before surgery. • A urinary drainage bag with an accurate measuring device that's used to record urinary output at regular intervals.
question
What are the 5 diuretic classification classes?
answer
Loop diuretics Thiazide diuretics Potassium-sparing diuretics Carbonic Anhydrase Inhibitors Osmotic diuretics
question
What are the most common diuretics administered intraoperatively?
answer
• Mannitol (Osmitrol) - osmotic diuretic • Furosemide (Lasix) - loop diuretic
question
What is Flurosemide used for?
answer
• Decrease intracranial fluid / pressure. • Neuro surgery.
question
What is Mannitol used for?
answer
• As a osmotic diuretic. • To decrease intraocular fluid/pressure • To decrease intracranial fluid/pressure • To protect kidney function during aortic procedures
question
Name 4 Loop Diuretics
answer
• Bumetanide (Bumex) • Ethacrynic acid (Edecrin) • Furosemide (Lasix) • Torsemide (Demadex
question
What are Loop Diuretics used for?
answer
(Highly potent) • To remove fluid arising from renal, hepatic or cardiac dysfunction • To treat acute pulmonary edema • Decreases 20% of the K+ load • Example of a loop diuretic = Lasix
question
What are Thiazide Diuretics used for?
answer
(Low potency) • To treat essential hypertension and mild chronic edema • Decreases 5-10% of K+ load • Example of a thiazide diuretic = HydroDIURIL
question
Name 3 Thiazide Diuretics.
answer
• Bendoflumethiazide (Naturetin) • Chlorothiazide (Diuril, SK-Chlorothiazide) • Hydrochlorothiazide (Esidrix, HydroDIURIL, Oretic)
question
What are Potassium-sparing diuretics used for?
answer
(Low potency) • To treat edema and hypertension • To restore K+ levels in hypokalemic patients • Decreases 1-3% of K+ load • Example of a potassium-sparking diuretics = Aldactone
question
Name 4 Potassium-sparing diuretics.
answer
• Amiloride (Midamor) • Eplerenone (Inspra) • Spironolactone (Aldactone) • Triamterene (Dyrenium)
question
What are Carbonic Anhydrase Inhibitors used for?
answer
(Low potency) • To treat mild acute closed-angle glaucoma • To treat chronic open-angle glaucoma • Example of a Carbonic Anhydrase Inhibitor = Diamox
question
Name a Carbonic Anhydrase Inhibitor.
answer
Azetazolamide (Diamox)
question
What are Osmotic diuretics used for?
answer
(Mechanism of action unlike any other diuretic) • To increase blood pressure and volume by drawing fluid out of tissues and into the circulatory system rapidly. • Contraindicated in patients with hypertension and edema. • Example of a Osmotic diuretic = Osmitrol
question
Name a Osmotic diuretic.
answer
Mannitol (Osmitrol)
question
How does the hormone aldosterone affect kidney function?
answer
Increases reabsorption of sodium and water and the secretion of potassium in the kidneys.
question
Creatinine
answer
A chemical waste molecule that is generated from muscle metabolism.
question
Diuresis
answer
The elimination of large amounts of urine.
question
Dysrhythmia
answer
An abnormal heart beat.
question
Electrolytes
answer
• Minerals that are dissolved in body fluids. • Include sodium, potassium, calcium, chlorine, magnesium, bicarbonate, phosphate and sulfate • Found inside and outside of cells. • Acquired through food and water.
question
What is the electrolyte balance principle?
answer
Where the fluid goes, so go the electrolytes.
question
Homeostasis
answer
The balancing of fluids and electrolytes in the body by filtering blood and removing excess water and dissolved substances such as Na+ and K+.
question
Glaucoma
answer
An ocular disease, occurring in many forms, having as its primary characteristics an unstable or a sustained increase in the Intraocular Pressure which the eye cannot withstand without damage to its structure or impairment of its function.
question
Hypertension
answer
Persistently high systemic arterial blood pressure.
question
Ascites
answer
The accumulation of fluid in the abdominal cavity.
question
Congestive Heart Failure (CHF)
answer
• Aka. pump failure • The inability of the heart to pump sufficient blood to meet the body's demands. Back-pressure from stagnant blood slows down the venous blood return to the heart.
question
What happens to the body when the RIGHT ventricle fails during CHF?
answer
• Congestion of organs and extremities results • Legs become swollen • Liver becomes enlarged due to fluid retention • Enlarged liver presses on nerves causing pain and nausea. • Pressure in the abdominal veins can lead to accumulation of fluid in the abdominal cavity (ascites).
question
What happens to the body when the LEFT ventricle fails during CHF?
answer
• Pulmonary congestion and edema as fluid builds up in the alveoli • Accumulation of fluid in the lungs causes shortness of breath (dyspnea • Impaired function in major organs • Brain receives less blood which means less oxygen (hypoxia) • Confusion, loss of concentration and mental fatigue • Kidney function impaired resulting in less urine formation (oliguria) • Renal failure leads to abnormal retention of water and sodium thus leading to edema
question
Hypoxia
answer
Deficiency in the amount of oxygen reaching the tissues.
question
Oliguria
answer
The production of abnormally small amounts of urine
question
What natural mechanisms does the body have to adapt to decreased cardiac output?
answer
• Heart enlarges the pumping chambers to hold greater blood volume thus increasing the amount of blood pumped with each contraction. • Heart increases it's muscle mass • Sympathetic nervous system activates processes to increases the heart rate, redistribute peripheral blood flow and retain urine
question
What is the importance of potassium in cardiac function?
answer
• Primary intracellular electrolyte in the body. • Plays a vital role in nerve impulse conduction, acid-base balance, and promotion of carbohydrate and protein metabolism. • Every cell in the body, especially muscle, requires a high K+ content to function. • Even a slight deviation in levels can cause problems.
question
What can happen with an excess of potassium?
answer
Excess K+ alters the normal polarized state of cardiac muscle fibers.
question
What can happen with an increase of potassium?
answer
High levels can block conduction of cardiac impulses.
question
Tachycardia
answer
Rapid heart rate
question
Bradycardia
answer
Slow heart rate
question
What can abnormal K+ levels do?
answer
Diminish excitability and conduction rate of the heart muscle and lead to cardiac arrest.
question
Osmosis
answer
The process of water moving through a semipermeable membrane from an area of lesser concentration of solute to an area of greater concentration of solute.
