No stupid questions

[ohbet]

Will some knowlegable nurses answer my 3 questions of the day? remember there are no stupid questions.

1.I know what a myocardial infaction is,but what is a Inferior MI?

2.I once heard a lecturer,she is a emergency dept. supervisor, say that giving a patient nitro.tab. sub.l.,for someone with chest pain,should give the patient a head ache,except of course if its old. Is this true in your practice? Should nitro give the patient a HA?

3.Ive read that D5W is a isotonic solution. But my question is: once infused and is in the vessels and the body isnt the sugar metabolized thus leaving a hypotonic solution?

[KRVRN, BSN, RN]

I knew D5W was hypotonic... Now for the life of me I can't remember about D10W. I learned that 5% of the D is metabolized immediately but then D5% plus W would be left.

So what about D10W? Isotonic?

[adrienurse, LPN]

[brushing up on her cardiovascular nursing and Fluid and Electrolyte readings] Obviously not my forte.

[Sleepyeyes]

D10 is hyPERtonic, i think...

[VickyRN, MSN, DNP, RN]

Sorry, l.rae, that it's taken me so long to get back to you. You had asked:

tell me more about the r side MI not tol MS ir NTG..l don't think l have heard this...but it makes sense......elaborate if you will please....

I have a nice article from Critical Care Nurse (February '95, pp22-27), entitled "Right Ventricular Myocardial Infarction: Detection, Treatment, and Nursing Implications," and I quote from this article:

"When the RCA becomes occluded, the area of myocardium distal to the occlusion becomes ischemic or even necrotic, if blood flow is not restored. Often the occlusion occurs in the proximal RCA and both the inferior left ventricle and the right ventricle are deprived of oxygen-rich blood. This condition results in MI.

"When right ventricular MI occurs, the infarcted area becomes stiff and noncompliant, and diminished contractility results. As contractility decreases, a smaller blood volume is ejected to the left ventricle, reducing stroke volume. Cardiac output is the product of stroke volume and heart rate; when stroke volume decreases, the heart rate must increase to maintain the same cardiac output.

"Systemic arterial pressure, measured as blood pressure, is directly dependent on cardiac output and systemic vascular resistance (SVR). As cardiac ouput decreases, arterial vasoconstriction occurs, increasing SVR, or afterload. The left ventricle now contracts against an elevated pressure gradient and must generate higher pressure in order to eject blood into the systemic circulation. Decompensation occurs when the left ventricle is unable to eject blood adequately against this high-pressure system. Cardiac output is further reduced, hypotension worsens, and if not promptly reversed, cardiogenic shock will ensue.

"Concurrently, the blood volume received by the failing right ventricle is greater than the volume it can eject; therefore, the pressure in the right ventricle rises. This increased pressure is reflected back throught the right atrium to the systemic ciruclation [central venous pressure].

"The patient with right ventricular MI may present with cool, clammy skin due to increased SVR, distended neck veins and peripheral edema as a result of increased central venous pressure, and hypotension secondary to decreased left ventricular cardiac output..... Changes in mentation or level of consciousness may occur and urine output will diminish...Lung sounds will be clear."

Any drugs which decrease central venous pressure (i.e., right ventricular end diastolic volume--right ventricular preload) are contraindicated---especially the cardiac staples NITROGLYCERIN, MORPHINE, and LASIX. (Also, afterload reduces are contraindicated.) Instead the patient is fluid bolused. By INCREASING volume status, the right ventricle distends, the systolic contraction is stronger, and stroke volume is increased. A larger blood volume is supplied to the left ventricle, which enhances cardiac output.

In COMBINED right ventricular MI and inferior left ventricular MI, fluid loading may not be tolerated due to the failing left ventricle. DOBUTAMINE increases contractility of both right and left ventricles and may be used instread.

Hope this helps. To diagnose a right sided MI, V1 will have ST elevation on a standard 12-lead EKG. Switch the anterior leads to right side these V-leads (V3R through V6R) should show elevation. (See attachment)

[VickyRN, MSN, DNP, RN]

Sorry, l.rae, that it's taken me so long to get back to you. You had asked:

tell me more about the r side MI not tol MS ir NTG..l don't think l have heard this...but it makes sense......elaborate if you will please....

I have a nice article from Critical Care Nurse (February '95, pp22-27), entitled "Right Ventricular Myocardial Infarction: Detection, Treatment, and Nursing Implications," and I quote from this article:

"When the RCA becomes occluded, the area of myocardium distal to the occlusion becomes ischemic or even necrotic, if blood flow is not restored. Often the occlusion occurs in the proximal RCA and both the inferior left ventricle and the right ventricle are deprived of oxygen-rich blood. This condition results in MI.

"When right ventricular MI occurs, the infarcted area becomes stiff and noncompliant, and diminished contractility results. As contractility decreases, a smaller blood volume is ejected to the left ventricle, reducing stroke volume. Cardiac output is the product of stroke volume and heart rate; when stroke volume decreases, the heart rate must increase to maintain the same cardiac output.

"Systemic arterial pressure, measured as blood pressure, is directly dependent on cardiac output and systemic vascular resistance (SVR). As cardiac ouput decreases, arterial vasoconstriction occurs, increasing SVR, or afterload. The left ventricle now contracts against an elevated pressure gradient and must generate higher pressure in order to eject blood into the systemic circulation. Decompensation occurs when the left ventricle is unable to eject blood adequately against this high-pressure system. Cardiac output is further reduced, hypotension worsens, and if not promptly reversed, cardiogenic shock will ensue.

"Concurrently, the blood volume received by the failing right ventricle is greater than the volume it can eject; therefore, the pressure in the right ventricle rises. This increased pressure is reflected back throught the right atrium to the systemic ciruclation [central venous pressure].

"The patient with right ventricular MI may present with cool, clammy skin due to increased SVR, distended neck veins and peripheral edema as a result of increased central venous pressure, and hypotension secondary to decreased left ventricular cardiac output..... Changes in mentation or level of consciousness may occur and urine output will diminish...Lung sounds will be clear."

Any drugs which decrease central venous pressure (i.e., right ventricular end diastolic volume--right ventricular preload) are contraindicated---especially the cardiac staples NITROGLYCERIN, MORPHINE, and LASIX. (Also, afterload reduces are contraindicated.) Instead the patient is fluid bolused. By INCREASING volume status, the right ventricle distends, the systolic contraction is stronger, and stroke volume is increased. A larger blood volume is supplied to the left ventricle, which enhances cardiac output.

In COMBINED right ventricular MI and inferior left ventricular MI, fluid loading may not be tolerated due to the failing left ventricle. DOBUTAMINE increases contractility of both right and left ventricles and may be used instread.

Hope this helps. To diagnose a right sided MI, V1 will have ST elevation on a standard 12-lead EKG. Switch the anterior leads to right side; these V-leads (V3R through V6R) should show elevation.

[Sleepyeyes]

Again, from the above-mentioned IVF article in a prior post:

http://www.findarticles.com/m3231/n10_v28/21224628/p1/article.jhtml

Sugar water

Dextrose fluids, which contain dextrose and free water, are available in concentrations of 2.5%, 5%, 10%, 20%, and 50%. Each percentage represents 1 gram of dextrose per 100 ml of fluid. For example, [D.sub.5]W provides 5 grams of dextrose per 100 ml of water, or 50 grams/ liter. The tonicity of [D.sub.5]W is 253 mOsm/liter.

Dextrose fluids also are available in combination with other solutions, such as sodium chloride or Ringer's solution.

Indications. Dextrose fluids provide calories for energy, sparing body protein and preventing ketosis, which occurs when the body burns fat. They also make it easier for potassium to move from the extracellular to the intracellular compartment. Dextrose fluids flush the kidneys with water, helping them excrete solutes, and improve liver function (glucose is stored in the liver as glycogen).

Concentrations of [D.sub.2.5]W and [D.sub.5]W are used to treat a dehydrated patient and to decrease sodium and potassium levels; they're also suitable diluents for many medications. More concentrated (hypertonic) fluids such as [D.sub.10]W are used to correct hypoglycemia. [D.sub.20]W and [D.sub.50]W with electrolytes can provide long-term nutrition as a part of total parenteral nutrition.

Precautions. Never mix dextrose with blood--it causes blood to hemolyze. Prolonged therapy with dextrose in water can cause hypokalemia, hyponatremia, and water intoxication by diluting the body's normal level of electrolytes.

Severe hyponatremia can lead to encephalopathy, brain damage, and death; young women are at highest risk. Look for signs of confusion and other changes in mental status. Closely monitoring your patient and her lab results--particularly serum sodium and potassium levels--can prevent complications. (For more on the dangers of dextrose fluid overload, see "Focusing on the Dangers of [D.sub.5]W" in the October issue of Nursing97.)

Keep 'em coming! This is a great review for me!

[Peeps Mcarthur]

If the D5W is mixed with NS at 0.09% wouldn't that make its solute isotonic?..............over.......

I'm months from pharmacology classes,but I do have a complete library...........IF I was interested in extracurricular speculation,what would I look up for the theory?

[l.rae]

Thanks Vicky...that was very informative....l am not sure we have ever dx a r side MI on any of my pts........but, some of them must have been... however, most are not obviously st elevated and sometimes not dx till cardiac enzymes are done, but.. seems we have always given the standard...thanks so much for taking the time to post all of that!.....LR

[Youda]

Originally posted by ohbet

Well thanks again all you helpful and knowledgeable nurses.

Just one follow up question on the IV fluids. So I understand now that D5W is hypotonic,which means that once its in the vessels it will enter the cell by osmosis.

But what happens when a combo of D5W and NS is ordered together? Why is this combo solution ordered,is it for volume repacement and nutrition?

Hypo and Hyper refer to the concentration of the SOLUTES, not the water content, relative to the concentration inside the cell.

Isotonic: is a solution that has the same concentration of solutes in both the cells and the extracellular fluids.

Hypotonic: is a solution that the concentration of solutes is LOWER outside the cell. Less SOLUTES, more water. So, more WATER has to travel into the cell to achieve equilibrium of the SOLUTE. Remember that water is a TRANSPORT molecule of the solutes. This can cause lysis of the cell. But, also remember that as more water travels INTO the cells, less water is available OUTSIDE the cells.

Hypertonic: is a solution that the concentration of solutes is HIGHER outside the cell. More SOLUTES, less water. Water travels OUT of the cells because more water is needed OUTSIDE the cell to achieve equilibrium of the extracellular fluids. Hypertonic solutions can dehydrate the cell or cause it to plasmolyze.

OK. Now why would a MD order a combination of NS a (isotonic solution) with D5W (a hypotonic), you asked? The hyportonic solution would cause the cells to become filled with more water at the expense of total fluid volume. The D5W, then, would cause a fluid volume deficit or HYPOTONIC DEHYDRATION. Hypotonic dehydration is almost always accompanied by a sodium deficiet, because sodium is the chief extracellular ion (electrolyte). The combination of NS with D5W would help replenish fluids both inside and outside the cell.

This combination is often used with dehydration d/t diarrhea where a lot of sodium is lost. Also for hypovolemic shock.

The dextrose in the D5W isn't for nutrition (there isn't enough glucose there for that), but because glucose is necessary to provide the energy necessary for all the functional processes of the cell: metabolism, respiration, reproduction, etc. And that is another huge topic in itself. The glucose is to help the little cells do what they're suppose to be doing to keep the person (the cells, tissues, organs, etc.) alive.

Are you sorry you asked ???