6. Edema (swelling due to an increase in interstitial fluid) is a com- mon clini

Question

6. Edema (swelling due to an increase in interstitial fluid) is a com- mon clinical problem. On one of your first days of an introduc- tory clinical experience, you encounter four patients who all have severe edema for different reasons. Your challenge is to explain the cause of the edema. In each case, try to explain the edema in terms of either an increase or a decrease in one of the four pres sures that causes bulk flow at capillaries (see Figure 19.17) ) First you encounter Mrs. Taylor in the medical ward awaiting a liver transplant. What is the connection between liver fail- ure and her edema? (Hint: Think about the liver's role in pro- ducing plasma proteins.) (2) Next you follow a resident to the obstetric ward, where Mrs. So is experiencing premature labor. Which of the pressures that drive bulk flow might be altered here? (Hint: What might the expanded uterus be pressing on?) (3) Then you are called to emergency, where Mr. Herrera is in anaphylactic shock. In anaphylactic shock, the capillaries be- come leaky, allowing plasma proteins that are normally kept inside the blood vessels to escape into the interstitial fluid. Which of the pressures driving bulk flow is altered in this case and in what direction is the change? (4) Finally, you go to the oncology ward where Mrs. O'Leary is recovering from surgery for advanced breast cancer that had infiltrated her right breast and axillary lymph nodes. All of her axillary lymph nodes were removed and unfortunately this severed most of the lymphatic vessels draining her right arm. You notice that her right arm is quite edematous. Why? Mrs. O'Leary is given a compression sleeve to wear on this arm to help relieve the edema. Which of the pressures driving bulk flow at the capillaries will be altered by the compression sleeve? rcess everything you need to

Explanation / Answer

Edema occurs due to excess build-up of fluid in the tissues as a result of increase in the movement of fluid across the capillary.

Bulk flow is one of the mechanisms by which capillary exchange is facilitated. Through bulk flow small, lipid-insoluble solutes in water moves across the capillary wall. The movement occurs in both the directions and depends on two major opposing forces namely hydrostatic pressure and colloidal osmotic pressure as well as the blood pressure and interstitial fluid hydrostatic pressure.

(1) Severe liver disease may lead to liver failure causing the retention of fluid. Liver failure leads to lowering of the level of protein albumin as well as other proteins in the blood. Albumin is the most abundant protein in the blood plasma and hence maintains the volume of blood. Albumin prevents the fluid from leaking out of blood vessels. Hence, when the level albumin in the blood decreases, fluid leaks into the abdomen and result in edema.

(2) The expanded uterus of Mrs. So might be pressing on her kidneys and urinary bladder. The pressure caused due to this will lead to reduced filtration rate and hence increases the retention of water. Moreover, the expanded uterus will also lead to the compression of iliac veins that may lead to reduced blood flow and increased capillary hydrostatic pressure. Thus, the rate of blood flow returning to the heart gets reduced.

(3) During anaphylactic shock the fluid gets built up in the body tissues resulting in edema. This occurs due to low osmotic pressure in the tissues and high osmotic pressure in the capillaries. The high osmotic pressure in the capillaries prevents the blood to enter the capillaries leading to edema.

(4) Since all of Mrs. O’Leary’s axillary lymph nodes were removed severed her lymphatic vessels. Lymphatic vessels are thus no longer able to drain the excess fluid causing the accumulation of fluid in her arms. A compression sleeve can reduce edema, since it would increase the hydrostatic pressure of interstitial fluids and improve the fluid circulation and thus decrease the amount of fluid leaking into her right arm. They also help the tissues to flush excess fluid away.

Related Questions

Navigate

• Browse (All)
• Browse 6
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.