Acid and base lecture 4

Nursing intervention for respiratory alkalosis

-Assess breathing pattern -Provide emotional support, stay with patient -Promote rest, and decrease sensory stimulation -Teach deep breathing, implement re-breathing measures -Assess temperature -Assess patient's heart rate and rhythm as hypokalemia may develop -Assess blood gases & electrolytes -Administer IV fluids & correct electrolyte imbalances

Signs and symptoms of metabolic alkalosis

-CNS: irritability, dizziness, agitation, confusion, hyperrelfexia, tingling or numbness around the mouth & toes, positive Chvostek's & Trousseau's signs -Neuro: convulsions, weak hand grips, difficulty standing, "charley horses" -CV: myocardial irritability, heart rate increases, pulse thready, patients on digoxin are at high risk for toxicity -Resp: try to compensate by slowing to shallow slow respirations which causes CO2 to be retained -Kidneys: compensate by retaining H ions & excreting bicarb to help restore balance *However, in presence hypokalemia kidneys conserve K and thus increase H ion excretion (these ions compete for renal excretion) thus a decrease in K will increase severity of metabolic alkalosis -Serum CL level is low due to an increase in bicarb causes decrease in CL

Nursing interventions for metabolic acidosis

-Treat the etiology -Correct & maintain the imbalance and neutralize the acid -Assess LOC -Assess vital signs -Assess safety risk: patient is at risk to fall due to weakness -Assess lab values *K levels increase as the body shifts K out of the cell trying to maintain electrical neutrality = hyperkalemia *ABG's -Assess I&O -Provide adequate rest -Maintain patent IV & administer IV solutions (isotonic & hypotonic) -Administer insulin therapy that helps to restore normal metabolism -Diet high in CHO to decrease in the body's utilization of fats and proteins for energy and resulting in ketoacidosis -Parenteral CHO provides fat free nutrition -Administer Na bicarb to neutralizes excessive acid -Meds to decrease diarrhea

Nursing intervention for metabolic alkalosis

-Treat the etiology and correct the imbalance -Assess LOC -Assess VS *Pulse - K changes affect cardiac activity *RR - decreased rate, apnea r/t compensatory responses of lungs as pt ​improves assess deeper and increases rate ventilation -Assess bowel sounds *May be paralytic ileus secondary to hypokalemia -Assess I&O -Assess lab data -Educate patient about *Diuretics K+ replacement *Taking excessive antacids

Acids

Acids: substances that release H+ ions when the substance is dissolved in H20, an acid in solution increases the concentration of free H+ in that solution. Stronger acids separate more readily in H2O than weaker acids.

base

Bases: substances that bind free H+ ions in solutions. Bases are H+ acceptors and act to reduce the concentration of free H+ in solutions. Stronger bases bind H+ more easily than weaker bases.

Signs and symptoms of metabolic acidosis

CNS: depression, headache, confusion, drowsiness, lethargy CV: bradycardia, heart block, delayed electrical changes, hypotension, and thready peripheral pulse Resp: Kussmaul respiration's - deep and rapid, not under voluntary control Neuro: hyporeflexia, skeletal muscle weakness, flaccid Skin: skin & mucous m

Metabolic acidosis

Condition of decrease in serum bicarbonate level The ratio of acid to base is altered with a decrease in bicarb Etiology of Metabolic Acidosis Overproduction of bicarb such as: Excessive oxidation of fatty acids: diabetic ketoacidosis & starvation Hypermetabolism: heavy exercise, seizure, fever, hypoxia Excessive ingestion of acids: ethanol, methanol, & salicylate intoxication Under elimination of hydrogen ions such as in kidney failure Underproduction of bicarb such as: kidney failure, pancreatitis, liver failure, dehydration Over elimination of bicarb such as with diarrhea or a GI fistula

Metabolic alkalosis

Condition of decreased H ions and high plasma bicarb The ratio of acid to base is altered with an increase in bicarb Etiology -Abnormal gain of bicarb or increase in base Excessive ingestion of antacids i.e. alka - seltzer, baking soda Parenteral administration: blood transfusion, sodium bicarb, TPN -Abnormal loss of hydrogen ions or decrease in acid: vomiting or GI suctioning -Renal H+ loss: use of diuretics (Lasix or thiazide) or if the fluid volume is low due to dehydration aldosterone is released leading to H and K excretion which effect Na, CL, and K concentration in ECF Factors Predisposing to Metabolic Alkalosis -Hypokalemia *R/T Diuretic Therapy: kidneys conserve K & excrete H+ ions. The K moves out of cell to maintain serum levels & H enters to maintain neutrality. *R/T Excessive Adrenal corticoid Hormones Hyperaldosteronism & Cushing's syndrome (adrenal hyperfunction = increase glucocorticoids) Cushing's syndrome can occur r/t-prolonged use of steroids or tumor hyperfunction anterior pituitary (aldosterone regulates H20 & electrolyte balance promotes retention of Na and excretion of K & H ions)

Respiratory acidosis

Condition of excess serum C02 levels Related T to retention of C02 An increase in C02 causes excess carbonic acid & increase in H ion which leads to decrease the pH It can be classified as acute or chronic

Acute respiratory acidosis

Etiology: -Reduced alveolar-capillary diffusion r/t ventilation perfusion imbalance secondary to acute pulmonary edema or emboli, pneumonia, TB -Airway obstruction r/t-increased secretions (mucus), foreign object, edema, bronchoconstriction, lymph node enlargement -Respiratory depression r/t overdose of respiratory depressants (narcotics, sedatives), electrolyte imbalances, increased intracranial pressure -Inadequate chest expansion r/t muscle weakness from electrolyte imbalances, fatigue, or disease; obesity & ascites or tight scar tissue around the chest

Respiratory Alkalosis signs and symptoms

Hyperventilation caused by hypoxia, fear, fever, pain, exercise, anxiety, pulmonary embolus, mechanical over ventilation. Or over stimulation of the respiratory center due to septicemia, brain injury, encephalitis, drug overdose of aspirin (salicylates). Signs and Symptoms -Hyperventilation syndrome: tinnitus, palpitations, sweating, dried mouth, chest tightness, N&V, blurred vision -Lightheadedness, dizziness, inability to concentrate, confusion -Hypocalcemia- decrease in serum Ca due to more Ca combining to serum proteins -Neuromuscular irritability - paresthesias - tingling sensation toes, fingers, lips, dizziness -May develop hyper-reflexia, muscular twitch, tetany, convulsions, laryngospasms -Hypokalemia- decrease in K due to a temporary shift of K+ into cells and H+ shifts out Acute state of respiratory alkalosis the pH will elevate; PaCO2 will be low; & the HCO3 will be normal Renal response to decrease in PaCO2 begins almost immediately but it is not evident for 6 - 8 hours the pH will be normal; PaCO2 will be normal; & the HCO3 will decrease

Chronic respiratory acidosis signs and symptoms

Impaired gas exchange related to trapping of C02 2° pulmonary tissue destruction (COPD) Chronic respiratory conditions asthma, bronchitis, emphysema, bronchiectasis (chronic dilatation of a bronchus or bronchi secondary to chronic bronchitis) Signs and Symptoms Decrease in pH & oxygen level CV: tachycardia, weak & thread pulse, peripheral pulses are difficult to find, hypotension Hyperkalemia -causing tachycardia or a dysrhythmia as H+ enter cells the K+ leaks out CNS: headache, lethargy to confusion, as it worsens leads to unresponsiveness Neuro: decreased muscle tone & deep tendon reflexes, as it worsens leads to flaccid paralysis Resp: shallow & rapid to attempt to blow off CO2 Skin: warm flushed skin, mucous membranes are pale & cyanotic In the chronic condition the kidneys will eventually compensate for the imbalance. Therefore, chronic respiratory acidosis is different from acute by presence of and elevated PaCO2 with a normal pH level.

Chemical buffering mechanisms

The 1st line of defense Chemical buffers are substances that act as sponges to soak up or release H+ ions Major changes in the pH of body fluids are prevented by removing or releasing H+ ions The body's major buffer system is the bicarbonate (HCO3) and carbonic acid (H2CO3) system This system regulates hydrogen concentration by maintaining a ratio of 20 parts base bicarbonate to 1 part carbonic acid If the ratio changes, acidosis or alkalosis results The advantage of a chemical buffer system is that it reacts immediately. It can handle relatively small fluctuations in hydrogen ion production & elimination under normal metabolic & health conditions. The disadvantage is that it cannot sustain regulation. Proteins are also a source of buffers. They can either bind or release H+, albumin, hemoglobin & globulins are also examples that buffer acids.

Cells

The 3rd line of defense Cells are capable of admitting or releasing excess H+ ions In acidosis excess H+ ions move from the plasma into the cell and potassium moves from the cell into the plasma. The opposite occurs in alkalosis. Compared with the chemical buffer systems & the lungs the cells are slow regulators requiring 2 hours to control shifts in H+ concentration.

Regulatory systems

The 4 regulatory systems that control acid base (pH) balance in order of activation are: ​1. Chemical buffering ​2. Lungs ​3. Cells ​4. Kidneys

Assessment of PH values

The best way to evaluate acid-base balance is to measure arterial blood gases. Our body generates large amounts of H+ during metabolism. As a result the body must be able to control H+ ion concentration & maintain pH within a narrow range that is compatible with life. If there are alterations in acid-base balance cellular metabolism & enzymatic processes can be affected. Acid base balance is critical to the maintenance of homeostasis.

Kidneys

The kidneys are the 4th line of defense. The most powerful regulator of acid-base balance Responds to large or chronic fluctuations in hydrogen ion production or elimination. Slowest to respond (hours to days) but has the longest duration. To compensate for acid-base imbalances the kidneys alter the rate of excretion of H+ and bicarbonate ions in the urine The kidneys regulate the bicarbonate (HCO3) level To decrease pH an increased excretion of bicarbonate & reabsorption of hydrogen ions occurs. To increase pH a decreased excretion of bicarbonate & reabsorption of hydrogen ions occur. Bicarbonate (HCO3) concentration in plasma is 21-28mEq/L At the same time kidneys secrete H+ ions & eliminate lactic acid and all acids except carbonic acid Kidneys will attempt to compensate for respiratory & metabolic imbalances If metabolic acidosis secondary to kidney failure it cannot compensate

Lungs

The lungs constitute the 2nd line of defense. Primarily assist when the fluctuation of hydrogen ion concentration is acute. The lungs role in acid-base balance involves the regulation of CO2 Lungs control the H2CO3 (carbonic acid) component of the HCO3/H2CO3 buffer system. CO2 is easier to measure directly & since it's in balance with the amount of carbonic acid in solution the acid component of acid base is expressed in terms of the amount of CO2 present not the amount of carbonic acid The lungs can regulate CO2 levels by altering the rate and depth of respirations. *Increase in hydrogen ions or increase in carbon dioxide the central respiratory neurons stimulate which increase the rate & depth of breathing, causing more carbon dioxide to be lost (blow off) & decreasing hydrogen ion concentration. *Decrease in hydrogen ions or decrease in carbon dioxide inhibits the central respiratory neurons causing a decrease in the rate & depth of breathing causing carbon dioxide to be retained, increasing hydrogen ion concentration. *Base overload will cause the rate of respiration to decrease so that CO2 is retained & combines with water which increases the carbonic acid part of the ratio Partial pressure of CO2 (PaCO2) in arterial blood is 35-45mm Hg *"p" stands for partial pressure - it refers to the pressure or tension exerted by this dissolved gas in the blood. It is called partial pressure because CO2 is only one of several gases contributing to the total pressure exerted. In humans the PaCO2 in arterial blood is equal to the pressure of CO2 in alveolar which is 40-mm Hg at sea level. The partial pressure of CO2 in arterial blood is referred to as PaCO2. The "a" refers to arterial blood.

PH

The ratio of acid to base in the body is expressed in terms of pH (the concentration of hydrogen ions) P - Negative logarithm pH - negative logarithm of hydrogen This expression means the pH has an inverse relationship with the hydrogen ion concentration The fewer hydrogen ions present the higher the pH & the more alkaline the solution The more H+ ions present the lower the pH; the more acidic the solution

Chronic respiratory acidosis nursing intervention

Treatment is focuses on improving ventilation and lowering the CO2. If the condition occurs due to a neuromuscular or drug overdose the correction is to improve the underlying cause. Aim is the improvement of ventilation/perfusion ratio, maintaining a patent airway & enhancing gas exchange Drug Therapy: promotes openly airways & thins secretions-bronchodilators, anti-inflammatories, mucolytic, fluids to correct electrolyte imbalance, antibiotics, diuretics to help with CHF & fluid volume excess Oxygen Therapy: give O2 at 2 liters, promotes gas exchange, use cautiously with COPD increasing O2 can lead to respiratory depression & arrest due to retention of CO2, assess ABG's and lung sounds Pulmonary Hygiene: postural drainage, teach deep breathing & cough, upright position (mid-high Fowler's), increasing fluids to thing secretions, suction to clear secretions, Ventilation Support: may be needed for pt's unable to maintain oxygen saturation above 90% or who have respiratory muscle fatigue Assess LOC, vital signs, mucous membranes & skin, I&O

PH values of the body

• Normal pH of the body is 7.35 - 7.45 • If the balance becomes upset the body fluid becomes either acidic (increase in H+ ions) or alkaline (¯ in H+ ions) ❖ pH greater than 7.35 is acidosis ❖ pH less than 7.45 is alkalosis