Acid-Base Imbalances and Compensatory Mechanisms

Fluid Compartments

• Body fluid divides into intracellular fluid (ICF) and extracellular fluid (ECF).
• ICF, contained within cells, makes up about two-thirds of total body water and includes electrolytes and glucose.
• ECF exists outside cells, making up about one-third of total body water, subdividing further.

Extracellular Fluid Subdivisions:

• Interstitial fluid resides between cells but not inside blood vessels.
• Intravascular fluid, also known as blood plasma, is the fluid inside blood vessels.
• Transcellular fluids exist in epithelial-lined cavities like cerebrospinal, synovial, pleural, and peritoneal fluids.
• The distribution and composition of these fluid compartments maintains cellular function, nutrient transport, waste removal, and an optimal internal environment.

Third Spacing

• Third spacing is the abnormal shift of fluid from the intravascular space into the interstitial space or body cavities.
• Conditions such as ascites, pleural effusions, intestinal obstructions, and severe burns can cause it.
• Despite consistent total body fluid, fluid becomes trapped or "third spaced" outside the vascular system.
• This results in decreased intravascular volume, potentially leading to hypovolemic shock.
• Clinically, third spacing presents as edema or fluid accumulation, particularly in areas like the abdomen or extremities.

Electrolytes and Albumin: Ranges and Abnormal Symptoms

• Sodium normal range is 135-145 mEq/L.
• Hyponatremia (less than 135 mEq/L) symptoms are nausea, confusion, fatigue, muscle cramps, and seizures.
• Hypernatremia (greater than 145 mEq/L) symptoms are extreme thirst, confusion, muscle twitches, and seizures.
• Calcium normal range is 8.5-10.2 mg/dL.
• Hypocalcemia (less than 8.5 mg/dL) symptoms are muscle cramps, numbness, seizures, and arrhythmias.
• Hypercalcemia (greater than 10.2 mg/dL) symptoms are nausea, vomiting, confusion, and kidney stones.
• Potassium normal range is 3.5-5.0 mEq/L.
• Hypokalemia (less than 3.5 mEq/L) symptoms are muscle weakness, cramping, and arrhythmias.
• Hyperkalemia (greater than 5.0 mEq/L) symptoms are muscle paralysis, peaked T-waves on ECG, and arrhythmias.
• Magnesium normal range is 1.8-2.4 mg/dL.
• Hypomagnesemia (less than 1.8 mg/dL) symptoms are muscle cramps, tremors, arrhythmias, and seizures.
• Hypermagnesemia (greater than 2.4 mg/dL) symptoms are nausea, vomiting, lethargy, and respiratory depression.
• Bicarbonate normal range is 22-28 mEq/L.
• Low levels of bicarbonate result in metabolic acidosis with symptoms like nausea, fatigue, and Kussmaul respirations.
• High levels of bicarbonate result in metabolic alkalosis with symptoms like confusion, arrhythmias, and muscle twitching.
• Albumin normal range is 3.5-5.0 g/dL.
• Hypoalbuminemia (less than 3.5 g/dL) symptoms are edema, ascites, and poor wound healing.
• Hyperalbuminemia (greater than 5.0 g/dL) symptoms are dehydration; rarely symptomatic.

Actions of Isotonic, Hypertonic, and Hypotonic Solutions

• Isotonic solutions share the same osmotic pressure as blood plasma and cells, causing no fluid shift between compartments, examples include 0.9% normal saline, 5% dextrose in water (D5W), Lactated Ringers (LR).
• Hypertonic solutions, with higher osmotic pressure than blood plasma and cells, pull water out of cells, causing cellular dehydration and shrinkage, examples include 3-5% saline solution, D10W, D5 in 0.9% NS, D5 in 0.45% NS, and D5 in LR.
• Hypotonic solutions have lower osmotic pressure than blood plasma and cells and cause water to move into cells, cellular swelling potentially leading to rupture if severe, exampless are 0.45% saline and LR.

Solution Administration

• Isotonic solutions are used to replace fluid losses and maintain intravascular volume without disrupting fluid balance.
• Hypertonic solutions like 3% saline treat severe hyponatremia by raising extracellular sodium concentration and pulling water out of cells, requiring cautious administration.
• Hypotonic solutions such as 0.45% saline treat hypernatremia by diluting extracellular fluid and allowing water to move into cells, also for fluid replacement in patients with elevated sodium levels.

Colloids and Crystalloids

• Colloids, including albumin, are hyper-oncotic and expand plasma volume by about four times their volume.
• Crystalloids are aqueous solutions of electrolytes or water-soluble molecules and are used to replace fluid losses, maintain fluid balance, and deliver medications, normal saline, Ringer's lactate, and dextrose solutions are examples
• Crystalloids are administered for fluid resuscitation in conditions like dehydration, hypovolemia, and shock.
• Colloids contain larger insoluble molecules like proteins or starches in a crystalloid solution, albumin, dextran, and hydroxyethyl starches are examples.
• Colloids are generally used when plasma volume expansion is required for hypovolemic shock, burns, or during surgery; colloids pull fluid into the vascular space from the interstitial space due to higher oncotic pressure.
• When albumin is administered intravenously, it increases osmotic pressure causing fluid to be pulled from the interstitial spaces into the vascular space, effectively expanding the plasma volume approximately 4 times the volume of albumin.

Albumin Effects

• Intravenously administered albumin expands plasma volume, increasing venous return to the heart, increasing cardiac output and blood pressure.
• Over-administration of albumin can cause pulmonary edema if excessive fluid enters the pulmonary vasculature, increasing hydrostatic pressure and leading to fluid leakage into the lung interstitium and alveoli.
• Albumin draws fluid into the vascular space, leading to increased renal perfusion, increased glomerular filtration rate, and resulting in increased urination.

Fluid Volume Deficit

• Symptoms of fluid volume deficit are thirst and dry mucous membranes and decreased skin turgor and dry skin.
• Other symptoms may include sunken eyeballs, orthostatic hypotension, rapid heart rate, fatigue, weakness, headache, and muscle cramps.
• Reduced urine output and concentrated urine can indicate a fluid deficit, along with elevated BUN and hematocrit levels.
• Severe cases include cool, clammy skin, altered mental status, oliguria or anuria, and hypotension, often progressing to hypovolemic shock; prompt fluid replacement is needed to prevent complications.

Fluid Volume Excess

• Symptoms of fluid volume excess includes edema in the legs, feet, hands, and shortness of breath.
• Other symptoms are distended neck veins, crackles or wheezing in the lungs, jugular venous distension, and ascites.
• Additional symptoms including increased blood pressure and decreased hematocrit and plasma protein levels.
• Severe fluid overload can lead to pulmonary edema with pink, frothy sputum and severe shortness of breath; fluid overload can also lead to congestive heart failure if the heart cannot handle the increased volume where prompt treatment with diuretics and fluid restriction is necessary.

Types of Edema:

• Edema as the accumulation of excessive fluid in the interstitial spaces between cells or body tissues.
• Localized edema is confined to a specific area, often due to injury, inflammation or obstruction.
• Generalized edema involves widespread swelling throughout the body, often seen in conditions like heart, liver or kidney disease. (called anasarca).
• Pitting edema leaves an indentation after pressing the swollen area.
• Non-pitting edema is firm, but not indented with finger pressure, as seen in lymphedema.
• Peripheral edema targets extremities like legs, ankles, and feet. Pulmonary edema involves fluid buildup in the lungs.
• Cerebral edema is an excess of fluid in the braing tissue which can be life threatening.
• Edema can be classified based on the underlying cause, such as cardiogenic, renal, or lymphatic edema.

Hormonal Regulators

• Hormones regulate fluid intake through various mechanisms.
• ADH increases water reabsorption by the kidneys, released from the posterior pituitary in response to changes in blood osmolarity.
• Aldosterone release from the adrenal cortex acts as a potent sodium conserver for the kidneys.
• The renin-angiotensin-aldosterone (RAA) system combats hypovolemia by increasing sodium and water retention through angiotensin II and aldosterone effects.
• Atrial natriuretic peptide (ANP) released by the heart promotes excretion of sodium and water by the kidneys reducing blood volume and blood pressure is promoted.

Organs Regulating Hormonal Balance

• The hypothalamus produces ADH, which is stored in and released from the posterior pituitary gland, increasing water reabsorption by the kidneys.
• The kidneys release renin, which initiates the renin-angiotensin-aldosterone system (RAAS), converting angiotensinogen to angiotensin I, which is further converted to angiotensin II, stimulating aldosterone release.
• The adrenal cortex releases aldosterone in response to angiotensin II, causing the kidneys to reabsorb more sodium and water, increasing blood volume.
• The heart atria releases ANP, countering RAAS by promoting excretion of sodium and water by the kidneys, reducing blood volume.
• Homeostasis in the integration of hormones from different organs for precise regulation of body fluid levels and blood pressure.

Fluid and Electrolyte Diagnostic Tests

• Included are serum electrolytes, serum hematocrit, hemoglobin, BUN, creatinine, renal function test, and liver function test.
• Serum electrolyte measure sodium, potassium, chloride, and bicarbonate levels, with comparisons to normal ranges detecting imbalances.
• The serum hematocrit measures the percentage of red blood cells which can indicate dehydration or overhydration.
• Hemoglobin, a protein in red blood cells that carries oxygen, low levels suggest anemia or fluid imbalance.
• BUN(blood urea nitrogen), a waste product filtered by the kidneys, elevated levels may indicate dehydration or kidney dysfunction.
• Creatinine, another waste product eliminated by the kidneys, rising levels signal impaired kidney function.
• Tests measuring BUN, creatinine, and GFR assess how well the kidneys are filtering wastes and maintaining fluid balance.
• The liver's role in fluid regulation and protein production are evaluated in liver function tests.
• Total solute concentration are measured in serum osmolality indicating fluid balance.
• Abnormal substances like protein or glucose that can alter fluid balance are checked for in urinalysis.
• Acid-base status impacting fluid and electrolyte regulation are assessed in arterial blood gasses.

Medications Causing Electrolyte Disturbances

• Depending of the type of diuretic drug, diuretics can cause metabolic alkalosis(high ph of blood or hypokalemia(decrease serum potassium), or, conversely, hyperkalemia(increased rate serum potassium.
• Steroids like prednisone can lead to metabolic alkalosis.
• Potassium supplements may cause gastrointestinal upset, ulcers, or diarrhea if taken in excess.
• Respiratory depressants that decrease respiratory rate and depth can result in respiratory acidosis.
• Antibiotics of nephrotoxicity, and certain antibiotics like vancomycin can cause hyperkalemia, while others like zosyn (piperacillin/tazobactam) may lead to hypernatremia.
• Calcium carbonate antacids can cause mild metabolic alkalosis with nausea and vomiting.
• Magnesium hydroxide (milk of magnesia) laxatives can deplete potassium levels, causing hypokalemia.
• Stimulant laxatives like dulcolax can disturb fluid and electrolyte balance if overused.

Common Medications

• Diuretics such as Lasix/furosemide, a loop diuretic, increases excretion of sodium, chloride, and water by inhibiting reabsorption in kidney tubules, side effects are hypokalemia, hyponatremia, dehydration and metabolic alkalosis, patients at risk for electrolyte imbalance and deficient fluid volume. Nursing Interventions.
• Monitor input/output, weight, electrolytes, encourage fluid and electrolyte replacements and patient teaching which includes weighting daily and reporting excessive thrist or urination,
• The classification for steroids such as prednisone includes glutocorticoid, and effects are anti-inflammatory and immunosuppressive. Side effects, and therefore a risk for fluid retention, hypokalemia, hyperglycemia and osteoporosis. To treat, monitor weight, blood glucose and potassiusm levels, and possibly administors potassium supplements with patients at risk of electrolyte imbalance and impaired glucose tolerance. Patient teaching will include instructions for dietary guidance, and swellings should be reported as well as an increase in thrist and/or urination.
• calcium carbonate (Tums) function is to neutralize an acid while producing constipation metabolic alkalosis and hypercalcemia. Nursing diagnosis includes risk for electrolyte imbalance, with interventions used to check calcium levels and monitor bowel movements Laxatives (Kayexalate) work by preventing potassium from being absorbed, with nursing interventions used to moniter levels and encourage hydration.

Nurses Abnormal Assessments

• Nurses need to assess the electrolyte balance and pay attention to intake and output. Additionally, the nurses need to assess the respiratory, integumentary, and circulatory function to understand what kind of fluid balance the patient is maintaining.

Acidosis and Alkalosis

• Acidosis causes can be metabolic are are associated with diabetic ketoacidosis, lactic acidosis, due to poor per-fusion, renal failure due to acid retention, respiratory causes, including hypoventilation, and carbon dioxide retention.
• Alkalosis causes can be metabolic and are associated with vomitting, and loss of hydrochloric acid, diuretic use, hyopkalemia, respiratiory uses are hyperventilation and exessive carbon dioxide loss.

Signs and Symptoms: Acidosis

• Symptoms include headaches, lethargy, confusion and commas are other symptoms. Kussmaul respirations, nausea vomiting and diarrhea. Fatigue ad cramping can also happen in acidosis

All the Signs and Symptoms: Alkalosis

• Headaches, diziness and seizure can be related to alkalosis. Twitching or cramping in Alkalotic patients has been documented. Aritmia can can be expected in these patients

Arterial Blood Gasses:

• The blood can be compenstated alkalotic or acidotic, or even uncompensated in patients with disorders. A detailed anaylsis is detailed in the file and easy to interpret.

Fluid and Electrolyte Imbalance:

• Excessive fluid losses can lead to dyhydration and electrolyte deficits, as well as kidney and liver disease, can all lead to an electrolite imbalance. It is the nurses job to provide the proper care by montering vital changes, and checking patients lab work for any indicators leading to an imbalance.

Lung Assessment

• Vesicular is normal, while crackling rales indicate fluid.

Primary Signs and Symptoms: COPD

• Cough and sputum as indicated by COPD has symptoms will indicate any underlying medical conditions that could exasberate and electrolyte imblance for any older adults. These issues need to be closely monitored for any serious complications.

Sleep Apnea

• Obstructions in the air way can be caused by having a narrow air way, and or a dysfunctional diaphram.