Hypovolemia: Causes, Symptoms & Treatment PDF

11/27/23, 4:38 AM Realizeit for Student Summary Hypovolemia is a decrease in the volume of blood in the body, which can be due to blood loss or loss of body fluids. Blood loss can result from external injuries, internal bleeding, or certain obstetric emergencies. Diarrhea and vomiting are common c...

11/27/23, 4:38 AM Realizeit for Student Summary Hypovolemia is a decrease in the volume of blood in the body, which can be due to blood loss or loss of body fluids. Blood loss can result from external injuries, internal bleeding, or certain obstetric emergencies. Diarrhea and vomiting are common causes of body fluid loss. Fluid can also be lost as a result of large burns, excessive perspiration, or diuretics. Inadequate fluid intake can also cause hypovolemia. At the onset of hypovolemia, the mouth, nose, and other mucous membranes dry out, the skin loses its elasticity, and urine output decreases. Initially, the body compensates for the volume loss by increasing the heart rate, increasing the strength of heart contractions, and constricting blood vessels in the periphery while preserving blood flow to the brain, heart, and kidneys. With continuing volume loss, the body loses its ability to compensate and blood pressure drops. At this point, the heart is unable to pump enough blood to vital organs to meet their needs and tissue damage is likely to occur. Treatment of hypovolemia depends upon its severity. The symptoms of hypovolemia and the symptoms of shock are very similar. As blood volume decreases, the body begins to compensate for the lack of volume by constricting blood vessels. Squeezing blood vessels makes the available space inside the cardiovascular system smaller, which means the relative volume of blood is adequate to create pressure and perfuse the tissues. These actions shunt blood away from the most distal parts of the body (which is usually the skin) and results in loss of color and less noticeable warmth (cool, pale skin). The heart rate increases to circulate available blood more quickly and to increase the blood pressure enough to offset the loss of volume (and pressure) in the vascular space. At this point, there is often very little change in measurable blood pressure. If the cause of the hypovolemia is not corrected and the body continues to lose fluid volume, the body responds by the following: Sweating (stress response to the loss of perfusion) Lightheadedness (as loss of perfusion affects the brain) Confusion Fatigue Decreased blood pressure If hypovolemia remains untreated and the cause is not corrected, the patient could become unconscious. The location of bleeding can be internal, such as abdominal bleeding, gastrointestinal or external. In cases of internal or gastrointestinal hemorrhage, sometimes the signs and symptoms of hypovolemia https://herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=0Dn26kXyU%2f6F5gOCz4%2f2IZsc2gfB3djkaGXwQ9ctgb2A3gz%2bCKrCW4cKwIi8CIqb… 1/6 11/27/23, 4:38 AM Realizeit for Student are the first indications of blood loss, rather than the observation of the bleeding itself. Shifting fluid out of the bloodstream can also cause hypovolemia. Severe dehydration can lead to hypovolemia as the tissues pull water out of the bloodstream to balance the loss. Even a patient with severe edema (swelling) in the extremities—such as a patient with congestive heart failure—can have hypovolemia. Even though the patient might have too much fluid in the body (resulting in swelling), they might not have enough in the cardiovascular system. This would result in hypovolemia. If the amount of fluid in the body is unchanged, but the size of the cardiovascular system expands, the patient can experience relative hypovolemia. In this case, there is no loss or shift of fluid, but the sudden increase in space in the blood vessels leads to the same loss of pressure and perfusion as hypovolemia. There is no definitive blood test for hypovolemia. Vital signs including blood pressure, pulse rate, capillary refill time, and respiratory rate all give clues about a patient's blood volume relative to his cardiovascular capacity. When doing a thorough history and physical exam, the nurse should ask the patient about fluid intake, history of vomiting or diarrhea, and urine output. The patient might also need to have orthostatic blood pressure testing. Changes in the vital signs between these positions could indicate the presence of hypovolemia. Treatment Fluid replacement is the treatment for hypovolemia. If the source is blood loss, a blood transfusion could be necessary for severe cases. Otherwise, an intravenous infusion may be required. The most important treatment is to correct the underlying cause of the hypovolemia. Fluid Volume Excess (FVE), or hypervolemia, refers to an isotonic expansion of the ECF due to an increase in total body sodium content and an increase in total body water. This fluid overload usually occurs from compromised regulatory mechanisms for sodium and water as seen in congestive heart failure (CHF), kidney failure, and liver failure. Excessive intake of sodium from foods, medications, IV solutions, or diagnostic dyes are also considered causes of FVE. Other medical conditions that could contribute to FVE are hemodialysis, peritoneal dialysis, and myocardial infarction. Restriction of sodium and water intake is vital for the treatment for hypervolemia in order to return the extracellular compartment to normal. Ultrafiltration or dialysis may be required for acute cases. https://herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=0Dn26kXyU%2f6F5gOCz4%2f2IZsc2gfB3djkaGXwQ9ctgb2A3gz%2bCKrCW4cKwIi8CIqb… 2/6 11/27/23, 4:38 AM Realizeit for Student Hypervolemia is a medical condition when you have too much fluid in the body, also described as having excess water retention or fluid overload. Healthy people have a certain amount of fluid in their bodies. When you have too much excess fluid, it can cause health complications such as swelling, high blood pressure, heart problems and more. Hypervolemia is common among people with chronic kidney disease (CKD) and renal failure because their kidneys are not working to remove excess fluid like healthy kidneys would. Signs and symptoms of hypervolemia Symptoms of hypervolemia can cause discomfort, stress on the body and even organ trouble. Signs of fluid overload may include the following: Rapid weight gain Noticeable swelling (edema) in the arms, legs, and face Swelling in the abdomen Cramping, headache, and stomach bloating Shortness of breath High blood pressure Heart problems, including congestive heart failure Causes may include the following: Kidney failure - The kidneys are responsible for removing excess fluid from the body. When the kidneys are not working well, fluid can build up. Congestive heart failure - When the heart is not pumping enough blood, the kidneys are not able to work as well, leaving excess fluid in the body. Liver failure or cirrhosis - The liver processes nutrients and filters toxins. When the liver is not working as it should, fluid can build up in the abdomen. Hormonal changes - Women may experience mild fluid retention as a normal part of premenstrual syndrome (PMS) or pregnancy. Excessive fluid retention related to hormonal changes may be a sign of high blood pressure and should be checked out by a doctor. IV fluids - Receiving too much IV fluid, especially if there are other health conditions present, can lead to fluid overload and swelling. Treatment There are several approaches to treatment for hypervolemia. One of the most common treatments for hypervolemia is diuretics. Diuretics are drugs that increase the amount of urine the body produces. Another treatment is dialysis in extreme cases. Parenteral fluid therapy usually involves the intravenous administration of crystalloid solutions, colloidal solutions, and/or blood products. The choice of fluid, the amount of fluid to be infused, and the rate of infusion are determined by the indication for fluid therapy. Fluid therapy with crystalloid solutions is used to resuscitate patients who are hypovolemic, to correct free water deficits in the https://herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=0Dn26kXyU%2f6F5gOCz4%2f2IZsc2gfB3djkaGXwQ9ctgb2A3gz%2bCKrCW4cKwIi8CIqb… 3/6 11/27/23, 4:38 AM Realizeit for Student case of dehydrated patients, to replace ongoing fluid losses, and to meet the fluid requirements of patients who cannot take fluids orally. The use of colloidal solutions is now controversial. However, colloidal solutions (such as albumin solution) may be indicated either as a monotherapy or in combination with crystalloid solutions in severe cases of low oncotic pressure. In the case of severe bleeding, the use of blood products must be considered. All patients on fluid therapy should be closely monitored using a combination of clinical parameters and laboratory tests to determine the end-point of fluid therapy. When fluid is lost for any reason, electrolytes become imbalanced, body systems are stressed, and cognitive function in the brain is impaired. Blood becomes concentrated, signaling the kidneys to retain water. As a result, urine output is decreased. When blood is “thicker,” the heart has to work harder, causing the pulse to increase in order to maintain blood pressure. All of these compensatory actions by the body put an already-compromised patient at risk. Replacement of fluids intravenously resolves the imbalance and restores normal body functions. Which IV solution to administer is related to the reason for the fluid loss. The three types of crystalloids are the following: Hypotonic: When the extracellular fluid has fewer solutes (osmolarity) than the fluid in the cells. Water will move from extracellular space into the cells (0.45% saline (1/2NS), 0.225% Saline (1/4 NS), 0.33% saline (1/3 NS)). Watch out for depleting the circulatory system of fluid since you are trying to push extracellular fluid into the cell to re-hydrate it. Never give hypotonic solutions to patient who are at risk for increased cranial pressure (can cause fluid to shift to brain tissue), extensive burns, trauma (already hypovolemic) etc. because you can deplete their fluid volume. Hypertonic: When the extracellular fluid has more solutes (osmolarity) than within the cells, water flows out of the cells (3% Saline, 5% Saline). When hypertonic solutions are used (very cautiously….most likely to be given in the ICU due to quickly arising side effects of pulmonary edema/fluid over load). In addition, it is prefered to give hypertonic solutions via a central line due to the hypertonic solution being vesicant on the veins and the risk of infiltration. Isotonic: Both the extracellular and intracellular fluids have the same osmolarity, so there is no movement of water between them (0.9% saline, 5% dextrose in Water). Isotonic solutions are used: to increase the EXTRACELLULAR fluid volume due to blood loss, surgery, dehydration, and fluid loss that has been loss extracellularly. Isotonic crystalloids should be used with caution in patients with cardiac or renal disease, as there is a risk of fluid overload. Patients’ sodium and chloride levels need to be monitored regularly to avoid hypernatraemia and hyperchloraemia. Blood needs the right balance of acidic and basic (alkaline) compounds to function properly. This is called the acid-base balance. The kidneys and lungs work to maintain the acid-base balance. Even slight variations from the normal range can have significant effects on the vital organs. https://herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=0Dn26kXyU%2f6F5gOCz4%2f2IZsc2gfB3djkaGXwQ9ctgb2A3gz%2bCKrCW4cKwIi8CIqb… 4/6 11/27/23, 4:38 AM Realizeit for Student The human body experiences four main types of acid-based disorders: metabolic acidosis, metabolic alkalosis, respiratory acidosis, and respiratory alkalosis. If one of these conditions occurs, the human body should induce a counterbalance in the form of an opposite condition. Acid-base balance in the human body is one of the most paramount physiological processes. The clinical significance of acid-base balance is one, which is hard to deny. Some of the most common admissions to hospitals are due to diseases that can dangerously affect the acid-base balance. This is why it is important for clinicians to understand basic principles, which govern this portion of human homeostasis. Lungs and Acid Base A constant amount of CO2 in blood, essential for normal acid-base balance, reflects a balance between that produced as a result of tissue cell metabolism and that excreted by the lungs in expired air. By varying the rate at which carbon dioxide is excreted, the lungs regulate the carbon dioxide content of blood. Most of the carbon dioxide diffuses into red cells, where it combines with water to form carbonic acid. The acid dissociates with production of hydrogen ions and bicarbonate. Hydrogen ions combine with deoxygenated hemoglobin (hemoglobin is acting as a buffer here), preventing a dangerous fall in cellular pH, and bicarbonate diffuses along a concentration gradient from red cell to plasma. Thus most of the carbon dioxide produced in the tissues is transported to the lungs as bicarbonate in blood plasma. At the alveoli in the lungs, the process is reversed. Hydrogen ions are displaced from hemoglobin as it takes up oxygen from inspired air. The hydrogen ions are now buffered by bicarbonate which diffuses from plasma back into red cell, and carbonic acid is formed. As the concentration of this rises, it is converted to water and carbon dioxide. Finally, carbon dioxide diffuses down a concentration gradient from red cell to alveoli for excretion in expired air. Respiratory chemoreceptors in the brain stem respond to changes in the concentration of carbon dioxide in blood, causing increased ventilation (breathing) if carbon dioxide concentration rises and decreased ventilation if carbon dioxide falls. Kidneys and acid-base balance Normal cellular metabolism results in continuous production of hydrogen ions. We have seen that by combining with these hydrogen ions, the bicarbonate buffer in blood minimizes their effect. However, buffering is only useful in the short term, and ultimately hydrogen ions have to be removed from the https://herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=0Dn26kXyU%2f6F5gOCz4%2f2IZsc2gfB3djkaGXwQ9ctgb2A3gz%2bCKrCW4cKwIi8CIqb… 5/6 11/27/23, 4:38 AM Realizeit for Student body. Furthermore, it is important that the bicarbonate that is used to buffer hydrogen ions is continuously replaced. These two tasks, elimination of hydrogen ions and regeneration of bicarbonate, are accomplished by the kidneys. Renal tubule cells are rich in the enzyme carbonic anhydrase, which facilitates formation of carbonic acid from carbon dioxide and water. Carbonic acid dissociates to bicarbonate and hydrogen ions. The bicarbonate is reabsorbed into blood and the hydrogen ions pass into the lumen of the tubule and are eliminated from the body in urine. This urinary elimination is dependent on the presence in urine of buffers, principally phosphate and ammonia ions. Most acid-base disturbances result from the following: disease or damage to organs (kidney, lungs, brain) whose normal function is necessary for acidbase homeostasis disease which causes abnormally increased production of metabolic acids such that homeostatic mechanisms are overwhelmed medical intervention (e.g. mechanical ventilation, some drugs) https://herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=0Dn26kXyU%2f6F5gOCz4%2f2IZsc2gfB3djkaGXwQ9ctgb2A3gz%2bCKrCW4cKwIi8CIqb… 6/6