HPA II EXAM 1QUESTIONS AND ANSWERS

HPA II EXAM 1QUESTIONS AND ANSWERS What is considered a normal plasma pH? - ANS-7.35-7.45 What is the pH range of plasma that is compatible with life? - ANS-6.8 to 7.8 What does a higher H+ concentration indicate? - ANS-Indicates increased acidity What does a lower H+ concentration indicate? - ANS-Indicates more alkalinity and an increased pH What are the buffer systems which maintain plasma pH? How do they work? - ANS-The kidneys and lungs are the major buffer systems within the body. Buffer systems prevent major changes by removing or releasing H+. There are normally 20 parts of bicarb to 1 part carbonic acid in plasma. How do the kidneys regulate pH? - ANS-Regulate the bicarb level in the extracellular fluid by regenerating bicarbonate ions as well as reabsorbing them from the renal tubular cells. They also can increase excretion of hydrogen ions and conserve biocarbonate ions to help restore balance When pH is alkalotic how can the kidneys work to help restore pH balance? - ANS-Through retainment of hydrogen ions and loss of bicarb ions When pH is acidotic how can the kidneys compensate to help restore pH balance? - ANS-Through excretion of hydrogen ions and retainment of bicarb Which type of compensation is faster: kidneys or lungs? - ANS-The lungs are faster while the kidneys usually take a matter of hours or days to correct a pH imbalance How do the lungs compensate when pH is altered? - ANS-Through retaining or blowing off of CO2. The lungs control the carbonic acid content of the ECF. When CO2 is increased, it increases the content of carbonic acid in plasma (CO2 dissolved in water becomes carbonic acid). In the reverse situation, when more CO2 is released through exhaling, the carbonic acid concentration decreases (thus increasing pH). In metabolic acidosis which system compensates? How does it do this? - ANS-The lungs compensate by blowing off more CO2 (increasing respiratory rate), in order to decrease carbonic acid presence and the kidneys excrete bicarb and retain H+. When the lungs are compensating in metabolic acidosis you will see a lower paCO2 level (below 35). In metabolic alkalosis which system compensates? How does it does this? - ANS-The lungs compensate by retaining CO2 (through decreasing the respiratory rate) and the kidneys compensate through increasing the retention of bicarb which increases the plasma level of carbonic acid. This causes paCO2 to rise (when the lungs are compensating in this condition you will see a paCO2 above 45). In respiratory alkalosis which system compensates? How does it do this? - ANS-The kidneys compensate by excreting more bicarb and retaining H+. This will cause the bicarb level to become lower when the kidneys are compensating (below 22) In respiratory acidosis which system compensates? How does it do this? - ANS-The kidneys compensate by excreting more H+ and retaining more bicarb ions. This will cause the bicarb level to become higher when the kidneys are compensating (above 26) How is acid-base balance measured? - ANS-Through an arterial blood gas (ABG) What should be done in preparation if a patient is to undergo an ABG? - ANS-1) Should explain to the patient what the test is (measures adequacy of oxygenation, ventilation, and perfusion) and that it requires an arterial puncture and collection of a blood specimen (can obtain from an arterial line) 2) Should perform an Allen test in order to determine that there is adequate perfusion (is done by compressing the radial and ulnar arteries simultaneously causing the hands to blanch while making a fist, once the patient opens their hand blood flow should be restored within 6 seconds) 3) Any supplemental oxygen or respiratory settings should be recorded on the specimen information 4) Arterial specimen must be immediately placed on ice when obtained and taken to the lab What test should be performed doing an ABG? How is this performed? - ANS-An Allen test should be done before an ABG in order to determine that there is adequate ulnar blood flow when taking an arterial sample from the radial artery. The hand is elevated and the patient is asked to make a fist for 30 seconds while the nurse compresses the radial and ulnar arteries simultaneously, causing the hand to blanch. After the patient opens their fist, the nurse should release pressure from the radial and ulnar arteries and the hand should turn pink within 6 seconds indicating adequate perfusion. What steps should be taken after obtaining an ABG sample? - ANS-1) Pressure should be applied for 5-10 minutes and the patient should be watched for evidence of bleeding 2) If the patient is on anticoagulants, pressure should be applied for longer 3) Supplemental O2 and respiratory settings should be recorded with the sample 4) The sample should be placed on ice and sent to the lab as soon as possible What is the normal value for pCO2? - ANS-35-45 mmHg What is the normal value for pO2? - ANS-Greater than 80 mmHg What is the normal value for HCO3? - ANS-22-26 mmHg What values on an ABG would you see if respiratory acidosis was occurring? - ANS-1) PaCO2 would be greater than 45 2) pH would be lower than 7.35 3) If compensation occurs would see higher levels of bicarb above 26 Why does respiratory acidosis occur? - ANS-Occurs due to the inadequate excretion of CO2 from the lungs which causes retention of CO2 and in turn the rise of the carbonic acid level in the blood. It is due to hypoventilation and is usually accompanied by a low PaO2 also Which type of condition is associated with a condition that leads to hypoventilation (bradypnea)? - ANS-Respiratory acidosis Name some examples of situations in which respiratory acidosis occurs - ANS-1) Acute pulmonary edema 2) Aspiration of a foreign object 3) Atelectasis 4) Pneumothorax 5) Overdose of sedatives which causes hypoventilation 6) Sleep apnea 7) Administration of O2 to a patient with chronic hypercapnia (such as COPD patients) 8) Severe pneumonia 9) Acute respiratory distress syndrome 10) Diseases that impair respiratory muscles such as muscular dystrophy, multiple sclerosis, myasthenia gravis, and Guillain-Barre syndrome 11) CNS depression 12) Drowning 13) Bronchial spasms seen in asthma patients 14) Improper mechanical ventilation that results in hypercapnia due to a low ventilation rate (such as a patient who is intubated) What are some clinical manifestations associated with respiratory acidosis? - ANS-1) Sudden hypercapnia can cause increased pulse (tachycardia) and increased respiratory rate 2) Increased blood pressure 3) Mental cloudiness or confusion 4) Feeling of fullness in the head (due to cerebral vasodilation and increased cerebral blood flow) 5) Decrease in level of consciousness 6) Ventricular fibrillation (may be the first sign seen in anesthesized patients) 7) Hyperkalemia (in an attempt to move H+ into cells and reduce the level in the blood) 8) Hypoventilation (causes retainment of CO2) 9) Severe acidosis may lead to bradycardia What type of electrolyte imbalance can occur with respiratory acidosis and why? - ANS-Hyperkalemia can occur as potassium move out of the cells in order to try and bring H+ into the cells and lower acidity of the blood What will you see on an ECG with hyperkalemia? - ANS-Peaked T waves, ST segment depression, and a shortened QT interval What type of symptoms will you see with hyperkalemia? - ANS-Muscle weakness, dysrhythmias, paresthesia, diarrhea, colic, nausea, irritability and anxiety What is the normal level for potassium? - ANS-3.5-5 What may be the first sign of respiratory acidosis if a patient is anesthetized? - ANS-Ventricular fibrillation What are some signs of severe respiratory acidosis? - ANS-Increasing intracranial pressure due to vasodilation can cause papilledema and dilated conjunctival blood vessels. Hyperkalemia can also result as potassium moves out of the cells into blood in order to reduce the levels of H+ Why is there a concern with administering O2 to a patient that has chronic hypercapnia (such as a COPD patient)? - ANS-A patient that has PaCO2 chronically greater than 50 mmHg does not use high CO2 levels as a respiratory stimulant and instead relies on O2 levels as the major drive for respiration. Administering oxygen may raise O2 levels in the blood to where that respiratory stimulant is lost and the patient develops "carbon dioxide narcosis" What is the main treatment for a patient with respiratory acidosis? - ANS-Treating the underlying cause (ex. using bronchodilators to treat bronchial spasms in asthmatics, using thrombolytics to remove pulmonary emboli) How is respiratory acidosis managed? - ANS-1) Should treat the underlying cause 2) Pulmonary hygiene measures to clear the respiratory tract of mucus and purulent drainage 3) Adequate hydration to keep mucus membranes moist and facilitate secretion removal 4) Supplemental oxygen as necessary (use caution in those that are chronically hypercapnic) 5) Fixing inappropriate mechanical ventilation (however this should be done slowly in order to avoid alklosis) 6) Maintaining a patent airway (such as suctioning) 7) Enhancing gas exchange (through pulmonary hygiene measures and placing patient in a semi-fowlers position) If a patient has respiratory acidosis due to inappropriate mechanical ventilation how is this managed? - ANS-Elevated PaCO2 must be decreased slowly in order to avoid causing rapid excretion of CO2 to the point where the kidneys are unable to excrete bicarb fast enough and alkalosis and seizures could occur What will you see on an ABG in the case of respiratory alkalosis? - ANS-1) pH will be higher than 7.45 2) PaCO2 will be lower than 35 3) Bicarb may be lower than 22 if compensation is occurring How does respiratory alkalosis occur? - ANS-Is always caused by hyperventilation which causes excessive blowing off of CO2 and lowering of carbonic acid levels in the blood. Name some conditions that can result in respiratory alkalosis - ANS-1) Extreme anxiety which causes hyperventilation 2) Hypoxemia 3) Early phase of salicylate (aspirin) intoxication 4) Gram-negative bactermia (sepsis, fever increases metabolic needs causing increased breathing) 5) Inappropriate ventilator settings which results in hyperventilation 6) Asthma with hyperventilation 7) Pain 8) Chronic respiratory alkalosis can occur due to chronic hepatic insufficiency and cerebral tumors and are usually asymptomatic What are some clinical manifestations of respiratory alkalosis? - ANS-1) Light-headedness as a result of cerebral vasoconstriction and decreased blood flow 2) Inability to concentrate 3) Numbness and tingling due to decreased calcium ionization 4) Tinnitus 5) Possible loss of consciousness 6) Tachycardia 7) Ventricular and atrial dysrhythmias 8) Hypokalemia (H+ is pulled out of cells to raise blood levels of acid in exchange for potassium) 9) Decreased calcium level due to inhibition of calcium ionization 10) Decreased phosphate levels as condition causes an increased uptake of phosphate by the cells What electrolyte levels are affected by respiratory alkalosis? - ANS-1) Potassium (can cause hypokalemia as potassium is pulled into cells in exchange for moving H+ into the blood as a way to compensate) 2) Calcium (can cause low calcium levels due to inhibition of calcium ionization) 3) Phosphate (can cause low phosphate levels due to phosphate being pulled into cells) What are some signs of hypokalemia? What ABG condition might you see this with? - ANS-May see fatigue, anorexia, nausea and vomiting, muscle weakness, polyuria, paresthesias, leg cramps, abdominal distention, paralytic ileus and flattened T waves and prominent U waves on an ECG. It is seen with respiratory alkalosis, as potassium moves into the cells in order to move H+ into the blood in order to compensate What are some signs of hypocalcemia? What ABG condition might you see this with? - ANS-Chvostek sign (twitching of muscles in the face) and trousseau sign when blood pressure cuff is inflated which causes carpal spasm. It can also present with seizures, stridor, carpopedal spasm, hyperactive reflexes, tetany, tingling of finger and around mouth, mental changes such as depression, confusion, delirium, prolonged QT interval, dyspnea, and laryngospasm. It can also present with hyperactive bowel sounds. It is seen in respiratory alkalosis as more calcium is bound to albumin and not ionized What is the normal lab range for calcium? - ANS-8.6 to 10.2 How is respiratory alkalosis managed? - ANS-1) Want to treat the underlying cause (for example if cause is anxiety want patient to breathe more slowly in order to allow CO2 to accumulate or treat with antianxiety agent) 2) Instructing patient on proper breathing techniques in order to slow down breathing 3) Monitoring electrolytes (can cause low potassium, phosphorus, and calcium) 4) Adjusting ventilator settings to slow down breathing What are signs of hypophosphatemia? What condition may you see this in? - ANS-May see in alklalosis as when the pH rises it causes phosphorus to move into the cells. It presents with muscle weakness, muscle pain, acute rhabomyolysis, insulin resistance (possible hyperglycemia), and bruising and bleeding from platelet dysfunction What are the normal lab ranges for phosphorus? - ANS-2.5 to 4.5 Why does metabolic acidosis occur? - ANS-Common clinical disturbance characterized by a low pH (increased H+ concentration) or a loss of bicarb. It is divided into two forms which are classified according to the values of the serum anion gap: high anion gap acidosis and normal anion gap acidosis. What values on an ABG would you expect to see with metabolic acidosis? - ANS-1) pH below 7.35 2) Bicarb below 22 (is the cardinal sign of metabolic acidosis) 3) PaCO2 is normal or low (depending on if respiratory system is compensating) What does the anion gap measure? - ANS-Refers to the difference between the sum of all measured positively charged electrolytes (cations) and the sum of all negatively charged electrolytes (anions). The sum of measured cations is typically greater than the sum of measured anions creating a gap. This gap reflects normally unmeasured anions (phosphates, sulfates, and proteins) in plasma which can increase the gap through replacement of bicarbonate. A higher anion gap suggests excessive accumulation of unmeasured anions and indicates high anion acidosis as the metabolic acidosis type (results from excessive accumulation of a fixed acid which occurs in ketoacidosis, lactic acidosis, late phase of salicylate poisoning, uremia, etc) What is the normal range for anion gap - ANS-8-12 mEq/L What level is considered high anion gap acidosis? - ANS-An anion gap over 30. Indicates metabolic acidosis is present regardless of pH or HCO3 level