Arterial Blood Gases
The Renal (Metabolic) Buffer Response
In an effort to maintain the pH of the blood within its normal range, the kidneys excrete or retain bicarbonate (HCO3-). As the blood pH decreases, the kidneys will compensate by retaining HCO3- and as the pH rises, the kidneys excrete HCO3- through the urine.
Convert the following values for arterial pH to [H+] concentration Arterial pH= 7.15
The [H+] is equal to 63nanoEq/L at a pH of 7.20 (40 X 1.25 X 1.25) and 80nanoEq/L at a pH of 7.10 ( 63 X 1.25). Thus, the [H+] at a pH of 7.15 is 72nanoEq/L [63 + 0.5 X (80-63)]
A patient with severe diarrhea has the following laboratory tests: Arterial pH = 6.98 PCO2= 13mmHg [HCO3-] = 3mEq/L What is the acid-base disorder?
This patient has a pure metabolic acidosis
What is the base excess? What is the reference range?
-The base excess indicates the amount of excess or insufficient level of bicarbonate in the system. -The normal range is -2 to +2 mEq/liter. Remember: A negative base excess indicates a base deficit in the blood
How long do the kidneys take to correct pH imbalance?
Hours to Days
What is the primary compensatory mechanism for metabolic acidosis?
Hyperventilation
What does hyperventilation do?
Hyperventilation enhances CO2 excretion and lowers the PCO2
Identify the equation shown below: pH = pK′ + log cHCO3- α x pCO2
Henderson-Hasselbalch equation
A patient with cirrhosis and ascites is admitted to the hospital with acute gastrointestinal bleeding due to ruptured esophageal varices. He is taken to surgery, where a portacaval shunt is performed. He is given a total of 19 units of blood before and during the surgery. Although the ascites was removed during the surgery, it begins to reaccumulate postoperatively. His laboratory tests were normal pre-operatively, but the following values are obtained 12hrs after surgery: Arterial pH = 7.53 PCO2= 50mmHg [HCO3-] = 40mEq/L 1) What is responsible for the development of the metabolic alkalosis? 2) What would you expect the urine pH and Na+ concentration to be?
1) The acute metabolic alkalosis is due to the citrate load from the multiple blood transfusions. 2) The urine Na+ should be less than 15mEq/L and the urine pH acid (due to maximum NaHCO3 re-absorption), since effective volume depletion persists. It is possible, however, that HCO3-reabsorptive capacity may not be sufficiently increased to reabsorb all of the marked increment in the filtered HCO3- load. In this setting, the urine Na+ concentration and pH may be elevated because of the obligatory NaHCO3 excretion. A low urine Cl- concentration will still be present, because the patient remains HypOvolemic.
What is the normal range for HCO3?
22-26 mEq/L
What is the reference range for pCO2 in arterial blood?
35-45 mmHg
What is the normal range of pO2 in arterial blood?
80-100 mmHg
What is the reference range for SaO2 aka arterial oxygen saturation?
95% to 100%.
A common cause of respiratory alkalosis is: a. hyperventilation. b. vomiting. c. emphysema. d. chronic obstructive pulmonary disease (COPD).
A
Carbonic acid concentration in blood plasma equals: a. 0.0307 mmol/L/mm Hg times the pCO2 value in mm Hg b. Apparent pKa of carbonic acid, 6.1, plus the pCO2 value in mm Hg c. pCO2 value in mm Hg plus HCO3 value in mmHg d. Bicarbonate concentration divided by the pCO2 value in mm Hg
A
Hypoventilation can compensate for: a. Nonrespiratory acidosis b. Mixed alkalosis c. Mixed acidosis d. Nonrespiratory alkalosis
A
The anticoagulant of choice for arterial blood gas measurements is ______ in the ______ state. a. Lithium heparin; dry b. EDTA; dry c. Potassium oxalate; liquid d. Sodium citrate; dry
A
Which of the following mechanisms is responsible for metabolic acidosis? a. Bicarbonate deficiency b. Diminished production of fixed acids c. Rapid and efficient elimination of organic acids d. Increased retention of HCO3-
A
Which of the following represents the body's compensation for metabolic acidosis? A) The patient hypoventilates and the kidneys respond in normal fashion. B) The patient develops a deep, rapid gasping type of respiration and the kidneys increase the conservation of bicarbonate. C) The patient develops a deep, rapid gasping type of respiration and the kidneys increase the conservation of bicarbonate. D) The patient's respiration slows dramatically and the kidneys conserve hydrogen ions.
B
The Respiratory (Lungs) Buffer Response
A normal by-product of cellular metabolism is carbon dioxide (CO2). CO2 is carried in the blood to the lungs, where excess CO2 combines with water (H2O) to form carbonic acid (H2CO3). The blood pH will change according to the level of carbonic acid present. This triggers the lungs to either increase or decrease the rate and depth of ventilation until the appropriate amount of CO2 has been re-established.
Which of the following conditions is classified as normochloremic acidosis? a) Diabetic Ketoacidosis b) Chronic pulmonary obstruction c) Uremic acidosis d) Diarrhea
A) Diabetic Ketoacidosis Bicarbonate deficit will lead to hypERchloremia unless the bicarbonate is replaced by an unmeasured anion. In diabetic ketoacidosis, acetoacetate and other ketoacids replace bicarbonate. The chloride remains normal or low and there is an increased anion gap.
Factors that contribute to a pCO2 electrode requiring 60-120 seconds to reach equilibrium include the: A) diffusion characteristics of the membrane B) actual blood pO2 C) type of calibrating standard (ie liquid or humidified gas) D) potential of the polarizing mercury cell
A) diffusion characteristics of the membrane Blood gas instrumentation [Tietz 2015, p 427]
Severe diarrhea causes: A) metabolic acidosis B) metabolic alkalosis C) respiratory acidosis D) respiratory alkalosis
A) metabolic acidosis Excessive loss of bicarbonate [Tietz 2015, p695]
The expected blood gas results for a patient in chronic renal failure would match the pattern of: A) metabolic acidosis B) respiratory acidosis C) metabolic alkalosis D) Respiratory alkalosis
A) metabolic acidosis reduced excretion of acids [Tietz 2015, p695]
Select the anticoagulant of choice for blood gas studies. A. Sodium citrate 3.2% B. Lithium heparin 100 U/mL blood C. Sodium citrate 3.8% D. Ammonium oxalate 5.0%
B
What is the ratio of bicarbonate to carbonic acid at a blood pH of 7.4? a. 10:1 b. 20:1 c. 25:1 d. 50:1
B
At blood pH 7.40, what is the ratio of bicarbonate to carbonic acid? A) 15:1 B) 20:1 C) 25:1 D) 30:1
B) 20:1 Normal ratio of (bicarbonate) / (carbonic acid) [Tietz 2015, p689]
Specimens for blood gas determination should be drawn into a syringe containing: A) no preservative B) heparin C) EDTA D) oxalate
B) heparin Arterial specimens are best collected anaerobically with lyophilized heparin anticoagulant in sterile syringes [Tietz 2015, p426]
Most of the carbon dioxide in the blood is in the form of: A) dissolved CO2 B) carbonate C) bicarbonate ion D) carbonic acid
C
What is the most probable acid/base imbalance in the patient described below? 26 YOM presents with the following signs and symptoms: Extreme hysteria Hyperventilating Pulse 105 BPM Lab data for ABG's: pH = 7.60 pCO2 = 28 mmHg HCO3- =26 mmol/L pO2 = 100 mmHg a. Respiratory acidosis b. Metabolic alkalosis c. Respiratory alkalosis d. Metabolic acidosis
C
The reference range for the pH of arterial blood measured at 37C is: A) 7.28-7.34 B) 7.33-7.37 C) 7.35-7.45 D) 7.45-7.50
C) 7.35-7.45 Arterial pH reference range [Bishop 2018, p370]
Normally the bicarbonate concentration is about 24 mEq/L and the carbonic acid concentration is about 1.2; pK= 6.1, log 20 = 1.3. Using the equation pH = pK + log [salt]/[acid], calculate the pH. A) 7.28 B) 7.38 C) 7.40 D) 7.42
C) 7.40 Given the values of bicarbonate, carbonic acid, and the pK, the pH can be easily calculated using the Henderson-Hasselbach equation. The Henderson-Hasselbach equation describes the derivation of pH as a measure of acidity (using the acid dissocation constant, pKa) pH= 6.1 + log[24/1.2] pH=6.1 +1.3 =7.40 in biological and chemical systems. [Tietz 2015, p423]
The following blood gas results were obtained: pH: 7.18 pO2: 86mmHg pCO2: 60mmHg O2 saturation: 92% HCO3: 21mEq/L (21mmol/L) TCO2: 23mEq/L (23mmol/L) base excess: -8.0mEq/L (-8.0mmol/L) The patient results are consistent with which of the following? A) fever B) uremia C) emphysema D) dehydration
C) emphysema Disease causing respiratory acidosis. [Tietz 2015, p697]
What are conditions that cause HypOventilation resulting in Respiratory ACIDOSIS?
Central nervous system depression related to head injury Central nervous system depression related to medications such as narcotics, sedatives, or anesthesia Impaired respiratory muscle function related to spinal cord injury, neuromuscular diseases, or neuromuscular blocking drugs Pulmonary disorders such as atelectasis, pneumonia, pneumothorax, pulmonary edema, or bronchial obstruction Massive pulmonary embolus Hypoventilation due to pain, chest wall injury/deformity, or abdominal distension
What acid-base disorder is represented by the following sets of arterial blood tests: pH = 7.47 PCO2 = 20mmHg [HCO3-] = 14mEq/L
Chronic respiratory alkalosis--- high pH low PCO2 Compensatory reduction in [HCO3-] Note: a low [HCO3-] does not necessarily reflect a metabolic acidosis
What acid-base disorder is represented by the following sets of arterial blood tests: pH = 7.08 PCO2 = 49mmHg [HCO3-] = 14mEq/L
Combined respiratory and metabolic acidosis--- low pH high PCO2 low [HCO3-]
Oxygen content in blood reflects: a. pO2 value b. O2Hb only c. O2 dissolved in blood plasma only d. The patient's total hemoglobin value e. All of these
D
Which of the following is a cause of metabolic alkalosis? A) Late stage of Salicylate poisoning B) Uncontrolled diabetes mellitus C) Renal failure D) Excessive vomiting
D) Excessive vomiting Metabolic alkalosis may be caused by several conditions, of which one is excessive vomiting. Other causes are (1) loss of hydrogen ions in renal acid losses that exceed acid production from cellular metabolism, (2) disproportionate chloride loss compared with HCO3 loss (ie, the plasma concentration of HCO3 increases upon restriction to a smaller space of distribution), and (3) HCO3 administration (unusual because additional HCO3 is very quickly eliminated by the kidneys)
Unless blood gas measurements are made immediately after sampling, in vitro glycolysis of the blood causes a: A) rise in pH and pCO2 B) fall in pH and a rise in pO2 C) rise in pH and a fall in pO2 D) fall in pH and a rise in pCO2
D) fall in pH and a rise in pCO2 If not immediately analyzed, failure to adequately chill blood gas specimens will allow glucose metabolism, which increases carbon dioxide and lowers pH [Tietz 2015, p 426]
Compensatory mechanisms during acute hemorrhage include: A) decreased cerebral and coronary blood flow B) decreased myocardial contractility C) renal and splanchnic vasodilation D) increased respiratory rate E) decreased renal sodium resorption
D) increased respiratory rate Acute hemorrhage triggers the potent vasopressor activity of both angiotensin and vasopressin to increase blood flow to the heart and brain via selective vasoconstriction of the skin, kidneys, and splanchnic organs. Adrenergic discharge also results in selective vasoconstriction of skin, renal, and splanchnic vessels. Myocardial contractility and heart rate are increased, with the resultant increased cardiac output. Hyperventilation is the typical response to the metabolic (lactic) acidosis associated with hemorrhagic shock and hypoperfusion. Aldosterone release, with subsequent increased renal sodium resorption, is mediated by angiotensin 2 and ACTH, which prevents further intravascular depletion.
In respiratory acidosis, a compensatory mechanism is the increase in: A) respiration rate B) ammonia formation C) blood pCO2 D) plasma bicarbonate concentration
D) plasma bicarbonate concentration Compensatory mechanism in respiratory acidosis [Tietz 2015, p 697]
What is the differential diagnosis of metabolic acidosis?
Differential Diagnosis: Increased Anion Gap Lactic acidosis (type A: cardiogenic, septic shock; type B: metabolic causes and toxins) Diabetic ketoacidosis Alcoholic ketoacidosis Uremic acidosis (usually at glomerular filtration rate <15-30 mL/min) Ethylene glycol toxicity Methanol toxicity Salicylate toxicity (mixed metabolic acidosis with respiratory alkalosis) Normal (Non-) Anion Gap GI HCO3- loss Defects in renal acidification (RTA types I, II, or IV)
Causes of Metabolic Alkalosis
Exogenous HCO3- loads Acute alkali administration Milk-alkali syndrome Effective ECFV contraction, normotension, K+ deficiency, and secondary hyperreninemic hyperaldosteronism Gastrointestinal origin Vomiting Gastric aspiration Congenital chloridorrhea Gastrocystoplasty Villous adenoma Renal origin Diuretics Posthypercapnic state Hypercalcemia/hypoparathyroidism Recovery from lactic acidosis or ketoacidosis Nonreabsorbable anions including penicillin, carbenicillin Mg2+ deficiency K+ depletion Bartter's syndrome (loss of function mutations of transporters and ion channels in TALH) Gitelman's syndrome (loss of function mutation of Na+-Cl- cotransporter in DCT) ECFV expansion, hypertension, K+ deficiency, and mineralocorticoid excess High renin Renal artery stenosis Accelerated hypertension Renin-secreting tumor Estrogen therapy Low renin Primary aldosteronism Adenoma Hyperplasia Carcinoma Adrenal enzyme defects 11β-Hydroxylase deficiency 17α-Hydroxylase deficiency Cushing's syndrome or disease Other Licorice Carbenoxolone Chewer's tobacco Gain-of-function mutation of sodium channel in DCT with ECFV expansion, hypertension, K+ deficiency, and hyporeninemic-hypoaldosteronism Liddle's syndrome
Fill in the Blank: The only 2 ways an alkalotic state can exist is from either too little pCO2 or too much ____________ .
HCO3
What is the most important extracellular buffer?
HCO3- which combines with H+ according to the following reaction: H+ + HCO3-(salt) <---> H2CO3(weak acid) <---> H2O + CO2
Metabolic alkalosis—respiratory acidosis
Key: PaCO2 higher than predicted; pH normal Example: Na+, 140; K+, 3.5; Cl−, 88; HCO3−, 42; AG, 10; PaCO2, 67; pH, 7.42 (COPD on diuretics)
What organ does HCO3 (bicarbonate) correlate with?
Kidneys
What are the laboratory findings in metabolic acidosis?
Laboratory Tests Blood pH, serum HCO3-, and Pco2 are decreased; hyperkalemia may be seen. Anion gap is increased (normochloremic), normal, or decreased (hyperchloremic). In lactic acidosis, lactate levels are at least 4 to 5 mEq/L but are commonly 10 to 30 mEq/L. The diagnosis of alcoholic ketoacidosis is supported by the absence of a diabetic history and no evidence of glucose intolerance after initial therapy. Urinary anion gap from a random urine sample (urine [Na+ + K+] - Cl-) helps differentiate between renal and GI etiologies of hyperchloremic (normal or nonanion gap) acidosis. The urinary anion gap is negative if the cause is GI HCO3- loss (diarrhea) since renal acidification remains normal and NH4Cl excretion increases. If the cause is distal RTA, the urinary anion gap is positive since the kidney cannot excrete NH4Cl.
What organ does pCO2 correlate with?
Lungs
A 43-year-old man with severe depression is brought into the emergency department after being found collapsed at home. His family states that he had been recently despondent, and they had not heard from him for 3 days. On physical examination, he is unresponsive and tachypneic with a respiratory rate of 41 breaths/min despite a normal lung examination. His chest radiograph is unremarkable. An arterial blood gas (ABG) shows a pH of 6.93, Paco2 of 20 mm Hg, Pao2 of 100 mm Hg, and an HCO3- of 4 mEq/L. Serum electrolyte tests show an anion gap of 35. What are the salient features of this patient's problem? How do you think through his problem?
Metabolic Acidosis Salient features: Severe depression with risk for suicide attempt; tachypnea without evidence of lung disease; acidemia with decreased Paco2 and increased anion gap How to think through: The emergency department team has obtained the most crucial test for a nonresponsive, tachypneic patient: the ABG. ABG interpretation is complex, and the test is typically obtained during inherently stressful clinical circumstances, necessitating a systematic approach. Is the patient hypoxic? (No.) Is he acidemic or alkylemic? (Acidemic.) Is the primary cause metabolic or respiratory? (Metabolic. He is hyperventilating, effectively reducing the Paco2 well below the normal value of 40 mm Hg.) Is there an anion gap? (Yes, the anion gap is 35.) The disorder can now be named: anion-gap metabolic acidosis with compensatory respiratory alkalosis. What is the differential diagnosis of this disorder? (Diabetic or alcoholic ketoacidosis, uremia, lactic acidosis, ethylene glycol or methanol ingestion, salicylate or paraldehyde intoxication, isoniazid or iron overdose.) The history of depression raises the concern for a suicide attempt by an ingestion. Which of the above should be prioritized, and what should be the next diagnostic steps? (An osmol gap would support methanol or ethylene glycol ingestion. The serum salicylate level should also be checked.) What is the treatment for methanol or ethylene glycol ingestion? (Fomepizole, a competitive inhibitor of alcohol dehydrogenase; hemodialysis.) When ingestion of any substance is suspected, coingestion should be considered (eg, a serum acetaminophen level should always be checked).
What are the symptoms and signs of metabolic acidosis?
Metabolic Acidosis Symptoms and Signs Symptoms are mainly those of the underlying disorder or toxicity. Compensatory hyperventilation may be misinterpreted as a primary respiratory disorder. When severe, Kussmaul respirations (deep, regular, sighing respirations indicating intense stimulation of the respiratory center) occur. Acid-base disorders may be mixed; mixed acid-base disorder occurs frequently in alcoholism. Three major types of renal tubular acidosis (RTA) can be differentiated by the clinical setting: urinary pH, urinary anion gap, and serum K+ level.
What are the essentials of diagnosis and general considerations regarding metabolic acidosis?
Metabolic Acidosis Essentials of Diagnosis Metabolic acidosis can be classified as either an increased or normal or decreased anion gap. Anion gap = Na+ - (HCO3- + Cl?). The hallmark of increased anion gap metabolic acidosis is that the low HCO3- is associated with normochloremia (normal serum Cl-), so that the anion gap increases. In contrast, in a normal (non-) anion gap metabolic acidosis, the low HCO3- is associated with hyperchloremia, so that the anion gap remains normal. General Considerations Calculation of the anion gap is useful in determining the cause of the metabolic acidosis. A normochloremic (increased anion gap) metabolic acidosis generally results from addition to the blood of organic acids such as lactate, acetoacetate, β-hydroxybutyrate, and exogenous toxins (eg, ethylene glycol, methanol, or salicylate). Most common causes of hyperchloremic, normal (non-) anion gap metabolic acidosis are gastrointestinal (GI) HCO3- loss and defects in renal acidification (renal tubular acidoses).
What are the treatments for metabolic acidosis?
Metabolic Acidosis Medications The underlying disorder should be treated (eg, restoration of tissue perfusion, volume resuscitation). In salicylate intoxication, alkali therapy helps convert salicylate to salicylic acid and thus prevent central nervous system damage. In methanol intoxication, fomepizole, ethanol, or both are used to inhibit alcohol dehydrogenase and mitigate toxicity. Treatment of RTA is mainly achieved by administration of alkali (as either bicarbonate or citrate). The addition of thiazides in RTA may reduce the amount of alkali required. Fludrocortisone may be effective in RTA cases with hypoaldosteronism.
What acid-base disorder is represented by the following sets of arterial blood tests: pH = 7.32 PCO2 = 28mmHg [HCO3-] = 14mEq/L
Metabolic acidosis--- low pH low [HCO3-] Compensatory reduction in PCO2
What acid-base disorder is represented by the following sets of arterial blood tests: pH = 7.51 PCO2 = 49mmHg [HCO3-] = 38mEq/L
Metabolic alkalosis--- high pH high [HCO3-] Compensatory elevation in PCO2
What are the classic signs and symptoms of Metabolic acidosis?
Neurological headache confusion restlessness lethargy stupor or coma Cardiovascular dysrhythmias warm, flushed skin Pulmonary Kussmaul's respirations Gastrointestinal nausea and vomiting
What are some signs and symptoms of Respiratory Alkalosis?
Neurological light-headedness numbness and tingling confusion inability to concentrate blurred vision Cardiovascular dysrhythmias palpitations diaphoresis Miscellaneous dry mouth tetanic spasms of the arms and legs
What conditions can cause hyperventilation resulting in respiratory alkalosis?
Psychological responses, such as anxiety or fear Pain Increased metabolic demands, such as fever, sepsis, pregnancy, or thyrotoxicosis Medications, such as respiratory stimulants Central nervous system lesions
What are some signs and symptoms of Respiratory Acidosis?
Pulmonary dyspnea respiratory distress shallow respirations Neurological headache restlessness confusion Cardiovascular tachycardia dysrhythmias
What are some causes of increased acids resulting in Metabolic acidosis?
Renal failure Diabetic ketoacidosis Anaerobic metabolism Starvation Salicylate intoxication
If both the pCO2 and the HCO3 are abnormal, but the pH is in the normal range, look at the pH again.
We only use a single value of 7.40 as "normal" when both the pCO2and HCO3 are abnormal (indicating that some degree of compensation exists) and the initial pH is normal
How do you know when compensation is occurring?
When an acid-base disorder is either uncompensated or partially compensated, the pH remains outside the normal range. In fully compensated states, the pH has returned to within the normal range, although the other values may still be abnormal.
What is the formula for [H+]?
[H+] = 24 X (PCO2/ [HCO3-]) If the normal arterial PCO2 is 40mmHg and the [HCO3-] is 24mEq/L, then the normal [H+] is 40nanoEq/L
Convert the following values for arterial pH to [H+] concentration Arterial pH= 7.60
[H+]= 26nanoEq/L (40 X 0.8 X 0.8)
A 68-year-old man arrives in the emergency room with a glucose level of 722mg/dL (39.7mmol/L) and serum acetone of 4+ undiluted. An arterial blood gas from this patient is likely to be: a) low pH b) high pH c) low pO2 d) high pO2
a) low pH Interpretation of metabolic acidosis
Which of the following represents the compensatory response of the kidney and lungs to a patient whose is in metabolic acidosis?
a. The kidneys will increase bicarbonate reabsorption and the patient will begin to breathe very deeply and often gasp for air.
Which of the following correctly represents the mnemonic used to assess patients with possible metabolic acidosis?
a. MUDPILES
pCO2 >45 = ?
acidosis
HCO3 > 26 = ?
alkalosis
pH > 7.45 = ?
alkalosis
What is alkalemia?
an elevation in the blood pH (or a reduction in the H+ concentration)
A 43 YOF was arrived to the emergency department with altered level of consciousness. She complained of chronic but moderate severity acid indigestion. This was partially relieved by taking antacids. Her blood gases results are as follows: Results pH 7.60 pCO2 38 mm Hg HCO3- 40 mEq/L This patient demonstrates:
b. metabolic alkalosis.
What is HCO3 called?
bicarbonate
What is the most probable acid/base imbalance in the patient described below? 26 YOM presents with the following signs and symptoms: Extreme hysteria Hyperventilating Pulse 105 BPM Lab data for ABG's: pH = 7.60 pCO2 = 28 mmHg HCO3- =26 mmol/L pO2 = 100 mmHg a. Respiratory acidosis b. Metabolic alkalosis c. Respiratory alkalosis d. Metabolic acidosis
c
Which of the following compensatory mechanisms is correct for a patient in respiratory acidosis following? a. Decrease respiration rate b. Increase the movement of electrolytes such as Na+ and H+ out of the cells and into the blood while increasing K+ from blood into cells c. Decrease whole blood PCO2 d. Decrease plasma bicarbonate concentration
c
Primary respiratory disturbances (primary changes in PaCO2) invoke
compensatory metabolic responses (secondary changes in [HCO3−]),
primary metabolic disturbances elicit predictable
compensatory respiratory responses (secondary changes in PaCO2).
An arterial blood specimen submitted for blood gas analysis was obtained at 8:30 AM but was not received in the laboratory until 11AM. The technologist should: a) perform the test immediately upon receipt b) perform the test only if the specimen was submitted in ice water c) request a venous blood specimen d) request a new arterial specimen be obtained
d) request a new arterial specimen be obtained Arterial blood gases even maintained in ice water and anearobic conditions deteriorate within an hour due to diffusion through the plastic syringe. [Bishop 2018, p377]
A patient presents to the emergency department with diabetic ketoacidosis (DKA). The patient's blood glucose is 650 mg/dL and serum acetone is 3+. What would an arterial blood gas sample reveal? a. High pH and low bicarbonate b. Low pH and high bicarbonate c. High pH and high bicarbonate d. Low pH and low bicarbonate
d. Low pH and low bicarbonate
Which of the following descriptions accurately reflects the acid-base status of a patient's sample that was delivered to the laboratory on ice with bubbles present and was exposed to room air for 15 minutes? a. PCO2 increased, CO2 content increased, and pH increased b. PCO2 decreased and CO2 content increased c. PO2 decreased and bicarbonate increased d. PO2 increased and bicarbonate decreased
d. PO2 increased and bicarbonate decreased
Respiratory alkalosis can be seen in patients with: a. severe diarrhea. b. chronic obstructive pulmonary disease (COPD). c. mechanical hypoventilation. d. hysterical hyperventilation.
d. hysterical hyperventilation.
Diarrhea and intestinal fistulas may cause ______________ levels of base.
decreased
What is Acidemia?
defined as a decrease in the blood pH (or an increase in the H+ concentration)
If the pH is between 7.35-7.45, the condition is ___________ compensated.
fully
Hypercapnia(excess CO2) is usually the result of ____________________ rather than of increased CO2 production
hypoventilation
______________ ventilation will correct respiratory acidosis
increasing
What is Respiratory alkalosis?
is defined as a pH greater than 7.45 with a PaCO2 less than 35 mm Hg.
What is Metabolic acidosis?
is defined as a bicarbonate level of less than 22 mEq/L with a pH of less than 7.35. caused by either a deficit of base in the bloodstream or an excess of acids, other than CO2
What is Respiratory acidosis?
is defined as a pH less than 7.35 with a PaCO2 greater than 45 mm Hg.
The only 2 ways an acidotic state can exist is from either too much _______ or too little HCO3.
pCO2
Jane Doe is a 55-year-old female admitted to your nursing unit with sepsis. Here is her arterial blood gas result: pH 7.31 pCO2: 39 HCO3: 17 What is the ABG abnormality for each parameter? What organ is implicated as dysfunctional? What is the Final Diagnosis?
pH = Acidosis PaCO2 =Normal HCO3 = Acidosis Kidney (Metabolic) Dx: Metabolic Acidosis
Roxanne is a 54-year-old female admitted to your nursing unit. Here are the last ABG results: pH 7.29 (7.35-7.45) pCO2: 30 (35-45) HCO3: 18 (22-26)
pH = Acidosis pCO2 = Alkalosis HCO3= Acidosis = Kidneys Condition Kidneys (metabolic) + Acidosis= Metabolic Acidosis. Compensatory state Partially Compensated (b/c pH w/in 7.35-7.45)
John Doe is a 55 year-old male admitted to your nursing unit with recurring bowel obstruction. He has been experiencing intractable vomiting for the last several hours despite the use of antiemetics. His arterial blood gas result is as follows: pH 7.50 (7.35-7.45) PaCO2: 42 (35-45) HCO3: 33 (22-26) What is the ABG abnormality for each parameter? What organ is implicated as dysfunctional? What is the Final Diagnosis?
pH = Alkaline PaCO2 =Normal HCO3 = Alkaline Kidney (Metabolic) Dx: Metabolic Alkalosis
Rhianna is a 34 year-old female admitted to your nursing unit with thyrotoxicosis. Her blood gas results are as follows: pH 7.50 (7.35-7.45) pCO2: 30 (35-45) HCO3: 24 (22-26) What is the ABG abnormality for each parameter? What organ is implicated as dysfunctional? What is the Final Diagnosis?
pH = Alkalosis PaCO2 =Alkalosis HCO3 = Normal Lungs (Respiratory) Dx: Respiratory Alkalosis
Wonder Woman is admitted to your nursing unit. Her admission lab work reveals an arterial blood gas with the following values: pH 7.45 (7.40) pCO2: 48 (35-45) HCO3: 28 (22-26) What are the two matching values which determine what the problem is? What is the problem? For the two matching values, determine if the abnormality is due to the kidneys (metabolic) or the lungs (respiratory) What is the condition? Is the condition partially or completely compensated?
pH = Alkalosis pCO2 = Acidosis HCO3= Alkalosis = Kidneys Condition Kidneys (metabolic) + Alkalosis = Metabolic Alkalosis. Compensatory state Fully Compensated (b/c pH w/in 7.35-7.45)
what type of electrode measures the blood pH?
pH Electrode
If the pH is outside the range of 7.35-7.45, the condition is only___________ compensated.
partially
A patient that overdoses with acetylsalicylic acid first develops:
respiratory alkalosis.
