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acid base balance
pathophysiology test 5
| Question | Answer |
|---|---|
| What are arterial blood gases used to determine? | 1. acid base balance 2. oxygenation status |
| Who draws ABG's? | 1. RN with special training 2. Person from the Lab 3. Respiratory Therapist |
| Where are the sites for drawing ABG's? | 1. radial artery 2. femoral artery 3. brachial artery 4. (infants) temporal artery |
| What is an Allen test and when is it done? | An Allen test is a test done to assess ulnar artery patency prior to doing a radial artery puncture. |
| What type of syringe do you need to do an ABG draw? | heparinized syringe |
| How much blood is needed for ABG draw? | 2.5 - 5 cc of arterial blood |
| What lab value must you check before doing an ABG draw? | platelet count to make sure they will clot appropriately after blood draw. |
| Why do you want to make sure you have no clots, no air bubbles and have the Arterial blood put on ice after when drawing up blood for ABG test? | to minimize the alteration of true O2 and CO2 values |
| When you are doing the ABG draw, how will you know if you have accessed the artery? | the blood will pulsate into the syringe |
| After drawing the ABG you must maintain firm pressure on the arterial site for how long? | at least 5 minutes (radial) 7 minutes (brachial) 10 minutes (femoral) (any problems with bleeding (heparin/coumadin) hold even longer) |
| If patient has any problem with bleeding and you have to obtain blood for ABG test, how long would you hold firm pressure on the artery after the draw? | at least 15 minutes |
| When holding the arterial site after a ABG draw you must have what two things? | sterile gauze and gloves on your hands |
| When doing an arterial blood draw you must include certain information on the Laboratory slip. What info should be included? | 1. T.P.R. 2. FIO2 3. ventilator settings 4. time drawn 5. Oxygen given (maske 5/Lmin or cannula 3L/min |
| What does FIO2 mean? | Fraction of inspired air - how much oxygen is being delivered in the room air (usually room air is about 21% oxygen) |
| Normal air contains how much oxygen? | about 21% with most of the gas being Nitrogen |
| What type of complications can occur when drawing up ABG's? | 1. wrong blood (venous blood) 2. Arterial thrombosis 3. Nerve Damage 4. Hematoma 5. Damage to artery with decreased peripheral perfusion 6. Bleeding |
| If you are drawing ABG's from a femoral artery and Pt develops a hematoma, why is this dangerous? | the patient can go into hypovolemic shock with a large femoral bleed |
| What symptoms would a patient have if you have damaged a nerve during ABG blood draw? | electric like pain, or numbness/paresthesia |
| When drawing blood for ABG's, one of the complications include arterial thrombosis. What are the symptoms of this condition? | 1. pallor 2. pain 3. pulselessness distal in puncture 4. temperature (cool) |
| Why is it important to check distal pulses prior to doing ABG draw? | to make sure the person has proper tissue perfusion and to compare after draw to make sure that you have not caused an arterial thrombosis |
| When you are taking blood from the radial artery for a ABG draw, what pulse would you check prior to drawing the blood? | Thenar pulse (below the thumb) |
| When drawing ABG blood from femoral artery what pulses would you check prior to the draw? | Pedal, post-tibial, and popliteal pulses |
| What is the FiO2 up in the mountains | about 19% (sea level is 21%) |
| What are the gas components of air? | 1. Nitrogen - 79% 2. Oxygen 21% 3. Carbon Dioxide .03% |
| What does partial pressure of gas mean? | each gas exerts a % of total air pressure |
| What does PaO2 mean? | Partial pressure of arterial oxygen |
| What does PA02 mean? | Partial pressure of Alveolar Oxygen |
| What does PaCO2 mean? | Partial pressure of arterial Carbon Dioxide |
| What does PACO2 mean? | Partial pressure of Alveolar Carbon Dioxide |
| What should you know about ABG PaO2 value for an elderly person? | for every year above the age of 60, a pt's "normal" PaO2 drops by 1 mm Hg. |
| what is the normal blood pH? | 7.35 - 7.45 |
| What is the normal ABG value for PaCO2? | 35-45 mm Hg |
| What are the "dead" ranges of blood pH? | 6.8 - 7.8 (anything between 6.9-7.7, still alive) |
| What is the normal ABG value for HCO3? | 22-26 mEq/L |
| what is HCO3? | Bicarbonate |
| What is the normal ABG values at sea level for PaO2? | 80-100 mm Hg. for an adult under 60 |
| a chemical (buffer) that keeps the pH of blood from becoming too acidic or too basic. | bicarbonate (HCO3) |
| (pulse ox) Oxygen saturation measures how much of the _________in the red blood cells is carrying oxygen (O2). | hemoglobin |
| What conditions may cause abnormal ABG values? | 1.Diabetes 2.Drug or alcohol overdose 3.kidney failure 4.Lung diseases 5. a blood clot in the lungs, or pneumonia 6.Severe dehydration from severe burns, vomiting, diarrhea, or taking water pills (diuretics)7.Severe infection (sepsis) |
| What does BE/BD (base excess/Base deficit mean) | refer to an excess or deficit in amount of base in the blood. BE is reported as a concentration in units of mEq/L, with positive numbers indicating an excess of base and negative a deficit. A typical reference range for base excess is −2 to +2 mEq/L.[1] |
| What mainly determines the BE/BD reading in the blood? | bicarbonate |
| What is a normal BE/BD (base excess) | +2 to -2 |
| What would a +3 BE/BD mean? | alkalosis |
| What would a -1 BE/BD mean? | acidosis |
| When someone is on oxygen you should wait _____ minutes after changing oxygen setting before drawing an ABG to assess for changes in oxygen status | 15-20 minutes |
| What is a normal SpO2? | 95% on room air (21% oxygen) |
| What change in spO2 would be cause for concern? | a sudden drop in 5 or more points |
| _____ is the measure of hydrogen ion concentration in a fluid | pH |
| the higher the concentration of hydrogne ions in a solution the _____ the pH | lower (more acidic) |
| The lower the concentration of H+ in a solution the ______ the pH | higher (more alkaline) |
| pH scale is from what number to what number with what number being neutral? | 1-14 with 7 being neutral |
| Arterial blood is slightly alkalotic or acidotic? | alkalotic (7.35-7.45) |
| Why must the blood pH remain in a narrow range? | for cellular enzymes to function |
| A pH less than ______ will result in death | 6.8 |
| A pH more than ______ will result in death | 7.8 |
| List three normal pH homeostatic mechanisms | 1. buffering system 2. respiratory system 3. renal system |
| The pH buffering system within the body works in ______ | seconds |
| the respiratory system takes how long to regulate pH imbalances | works in minutes |
| What does the respiratory system use and how to help regulate pH? | uses carbonic acid to regulate CO2 concentration |
| How long does the renal system take to regulate pH imbalances? | takes hours to days |
| what does the renal system use to regulate pH? | H+ and HCO3 |
| What is the major organ that regulates pH | lungs (respiratory system) |
| When you combine water and carbon dioxide what does it form> | carbonic acid H2CO3 |
| True or False the body produces more acids than bases | true |
| If carbonic acid goes up we have respiratory _______ | acidosis |
| if carbonic acid goes down we have respiratory _______ | alkalosis |
| If you are breathing too rapidly you are likely to get respiratory ________. | alkalosis |
| If you are not breathing enough you are likely to get respiratory _______. | acidosis |
| List the 5 buffering systems | 1. Carbonic Acid-Bicarbonate system 2. Phosphate Buffer 3. Hemoglobin Buffer 4. Protein Buffer 5. Cellular Buffer |
| List 2 controls of ventilation | 1. brain chemoreceptors 2. peripheral chemoreceptors |
| What is the dominant control of ventilation in healthy people? | brain chemoreceptors in respiratory center in medulla |
| brain chemoreceptors are located where | in medulla |
| what stimulates the brain chemoreceptors in the medulla? | carbon dioxide and hydrogen ion concentrations (carbonic acid) |
| Where are the peripheral chemoreceptors located? | in aortic and carotid arteries |
| What do the peripheral chemoreceptors respond to? | oxygen levels in the arterial blood |
| People with COPD (emphysema) breath on ______ drive | hypoxic |
| What is hypoxic drive? | when you breath in response to lowered oxygen levels in the blood (copd people are not letting go of enough co2 and thus oxygen affinity is still strong on hemoglobin, reducing concentration of tissue o2) |
| Why do you have people with COPD do pursed lip breathing? | to get the cO2 out of the alveoli so that on the next inhalation a larger percent of oxygen can be ionhaled into the alveoli |
| What is the normal acid base balance? | 1 part carbonic acid to 20 parts of bicarbonate |
| True or False The body will not overcompensate. | true |
| Acidosis and Alkalosis (respiratory and metabolic) both cause symptoms that affect what system | CNS |
| What are symptoms of acidosis? | 1. lethargic 2. apathy 3. stupor 4. delirium 5. coma |
| Acidosis decreases normal vascular responses to _______ | catecholamines (epinephring/norepinephrine) |
| Acidosis _____ arterial sphincters which cause _______ and flushed face, with warm dry skin. | dilates; headache |
| Alkalosis symptoms include? | pt irritable, nervous, anxious, convulsions, tetany, numbness, tingling, laryngeospasms, skin cool and moist |
| Acidosis causes hemoglobin to have a _____ affinity for oxygen | decreased |
| Alkalosis causes hemoglobin to have a _____ affinity for oxygen | increased (doesn't want to let go so tissues become hypoxic) |
| During alkalosis neuromuscular functions become impaired because _____ becomes more protein bound causing tetany symptoms. | calcium |
| what is the most dangerous aspect of tetany? | possible development of laryngeospasms |
| What are the 4 types of H+ imbalances? | 1. respiratory acidosis 2. respiratory alkalosis 3. metabolic acidosis 4. metabolic alkalosis |
| Describe Respiratory acidosis | 1. pH below 7.35 2. carbon dioxide is not being "blown off" 3. carbonic acid is being retained |
| What are some causes of respiratory acidosis? | 1)decreased respirations 2)Neurological disease (Guillain-Barre)or injury to respiratory center 3) drug overdose 4) respiratory failure (COPD, pneumonia, airway obstruction) |
| What are some reasons someone may experience decreased respirations? | 1. incisional pain 2. pleuritic pain 3. fractured ribs 4. burn eschar on chest 5. splinting |
| What drugs will cause decreased respirations? | narcotics and barbituates |
| What is the compensatory mechanism for respiratory acidosis? | kidneys retain bicarbonate (HCO3) |
| What occurs when too much CO2 is being blown off and not enough carbonic acid is being retained | respiratory alkalosis |
| True or False Respiratory alkalosis is often an early subtle sign of the onset of serious illness or complications in a hospitalized patient | true |
| What are some causes of respiratory alkalosis? | 1. hyperventilation 2. hypoxemic states 3. as a compensation for metabo0lic acid states |
| Explain why hypoxic states can cause respiratory alkalosis? | low levels of oxygen in the body stimulate the carotid and aortic receptors and this results in increased respiratory rate and then more carbonic acid is excreted via the lungs |
| When a person is in a ketoacidotic coma they can develop Kussmaul respirations (deep blowing respirations) which can result in? | compensating for acidotic state and therefore cause respiratory alkalosis |
| Respiratory alkalosis compensatory mechanism is ? | kidney's excrete bicarb |
| When the body is in an alkalotic state more free _____ binds to albumin leaving the body hypocalcemic. | ca+ |
| symptoms of acidosis are: | lethargy, sleepy, headache, vasodilation (flushed and dry skin) |
| symptoms of alkalosis are: | irritable, anxious, severe could be seizures or convulsions |
| caused by an excess production or retention of metabolic acids or the loss of base (HC03) | metabolic acidosis |
| What are some causes of metabolic acidosis | 1. excessive production or organic acids (diabetic ketones, hyperthyroidism, starvation, lactic acidosis) 2. retention of acids (renal failure) 3. ingestion of acid salts (aspirin) 4. excessive loss of base (severe diarrhea or pancreatic fistula) |
| If you have a pancreatic fistula what acid base imbalance may result? | metabolic acidosis (pancreas secretes base into intestine and a fistula would reduce base in system) |
| Severe diarrhea may result in what acid base imbalance | metabolic acidosis (base from pancreas not able to be reabsorbed) |
| caused by a loss of acid, gain of alkaline or hypokalemia | metabolic alkalosis |
| What are some causes of metabolic alkalosis | 1. excessive loss of acid fluids (protracted vomiting - pyloric stenosis), continuous nasogastric suctioning 2. excessive intake of alkaline salts 3. hypokalemia |
| What is the compensatory mechanism for metabolic acidosis? | lung excretes more H2CO3 |
| what is the compensatory mechanism for metabolic alkalosis? | lungs retain more H2CO3 |
| Most calcium is in the bones and _____ | teeth |
| Most of the calcium (small percentage) that is found in the blood is _____ bound. | protein |
| Calcium that is protein bound is _____ physiologically active. | NOT |
| True or false Only free or unbound calcium (ionized) can be physiologically active. | true |
| In ______ more calcium becomes protein bound or physiologically inactive so patient has the symptoms of hypocalcemia. | alkalosis |
| What are the symptoms of hypocalcemia? | tetany a form of neuromuscular irritability |
| What are some early signs of tetany? | tingling and numbness of lips and fingertips |
| What is the greatest danger of low calcium levels | tetany that causes laryngospasms (stridor) |
| When someone hyperventilates and goes into respiratory _______, they become anxious and develop numbness and tingling of the lips and finger tips due to _________. | alkalosis; hypocalcemia |
| Hypocalcemia can lead to tetany which can be detected by ______sign. | Chvostek (tap on side of head and face twitches) |
| What is it called when you tape over the 7th cranial nerve and the face twitches? | this is the Chvostek Sign which detects hypocalcemia |
| What is Trousseau's Sign and what does it detect? | apply B/P cuff and inflate to over the systolic pressure, hold cuff at this pressure for 3 minutes and watch for carpopedal spasm (test for hypocalcemia) |
| Hydrogen and ____ will switch places with each other (intravasular to intercellular shifting) | potassium (K+) |
| to maintain electrical neutrality chloride may change places with ______ | bicarbonate (HCO3) |
| too much cl- can drop ______ and cause acidosis | HCO3- |
| The main intracellular cation is | potassium |
| the main intravascular cation is | sodium |
| A cell needs a certain concentration or constant state of cations so when cells receive H+ ions it kicks ____ out. | K+ |
| pH is being pushed in the same direction | Mixed ABG |
| Why is a mixed ABG dangerous | because the pH is rapidly moving on one direction (no compensation can occur) |
| What are the 3 steps to determine Blood gas results? | 1. look at pH. Does it indicate acidosis or alkalosis 2. is the cause of the pH imbalance respiratory(Co2) or metabolic (hc03-) 3. is there compensation for the imbalance |
| A large anion gap indicates what? | metabolic acidosis |
Created by:
kellyaem