Arterial Blood Gas Interpritation Mark Bromley PGY-2.

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1 Arterial Blood Gas Interpritation Mark Bromley PGY-2

2 Why ABGs? Important clinical info Quick other labs (i.e. faster than a CBC) Fun to interpret

3 Why Not? ABG analysis is not without drawbacks. It is painful! Complications Local hematoma Arterial dissection and thrombosis (rarely) Technically difficult, particularly in children and elderly patients, and several attempts may be required.

4 Normal ABG parameters pH 7.40 PCO2 40 mmHg [HCO3] 24 mmol/l Anion Gap < 12

5 3 Processes Ventilation (CO2) Oxygenation (02) Acid-Base

6 4 Equations 3 Physiologic Processes Equation Physiologic Process 1) PaCO 2 equation ------------------------------------- Alveolar ventilation 2) Alveolar gas equation ----------------------------- Oxygenation 3) Oxygen content equation ------------------------- Oxygenation 4) Henderson-Hasselbalch equation -------------- Acid-base balance

7 PaCO2 Equation VCO 2 x 0.863 PaCO 2 = ----------------- VA PaCO2 reflects ratio of metabolic CO2 production to alveolar ventilation VCO2 = CO2 production VA = VE – VD VE = minute (total) ventilation VD = dead space ventilation 0.863 converts units to mm Hg

8 PaCO 2 VCO 2 Ventilation (0.863) =

9 PaCO2 Blood Alveolar Ventilation >45 mm Hg ------- Hypercapnia ----- Hypoventilation 35 - 45 mm Hg –- Eucapnia ---------- Normal ventilation <35 mm Hg -------Hypocapnia ------- Hyperventilation

10 PaCO 2 CO 2 production Alveolar Ventilation

11 Hypercapnea The only physiologic reason for elevated PaCO 2 is inadequate alveolar ventilation (VA) for the body’s CO 2 production (VCO 2 ) Hypercapnia can arise from insufficient total ventilation, increased dead space, or a combination of the two

12 Case 54 yr female presents with acute SOB Post colon resection for a malignant bowel obstruction Shortly after returning home from hospital she experienced sudden chest pain worse with inspiration.

13 Arterial Blood GasSerum ChemistriesUrine Tests pH: 7.40 p O 2 : 80 [Na + ]: 136 mEq/L pCO 2 : 20 mm Hg[Cl - ]: 106 mEq/L [HCO 3 - ]: 15 mEq\L

14 Pulmonary Embolus PaCO 2 CO 2 production (↑ ↑ ventilation) – (↑dead space)

15 Alveolar Gas Equation PAO 2 = PIO 2 - 1.2 (PaCO 2 ) Alveolar O 2 = P Inspired O 2 – Arterial CO 2 PIO2 = FIO2 (PB – 47 mm Hg) PIO2 = Inspired O2 (Barometric Pressure – 47 mm Hg) water vapor pressure at normal body temperature

16 This describes the factors that influence O2 in the alveoli Almost always, Alveolar O2 is higher than Arterial O2

17 Alveolar O 2 = P Inspired O 2 – Arterial CO 2 PIO2 = Inspired O2 (Barometric Pressure – 47 mm Hg ) Thus, when PAO2 ↓, PaO2 ↓

18 Why do I care? If everything else is constant… as ↑PaCO2 both PAO2 and PaO2 will decrease (hypercapnia causes hypoxemia) as ↓FIO2 both PAO2 and PaO2 will decrease (suffocation causes hypoxemia) as ↓PB (e.g., with altitude) both PAO2 and PaO2 will decrease (mountain climbing causes hypoxemia)

19 P(A-a)O 2 the “A-a gradient” P(A-a)O 2 is the alveolar-arterial difference in pO2 It results from gravity-related blood flow changes within the lungs (normal ventilation-perfusion imbalance) PAO 2 is always calculated PaO 2 is always measured

20 P(A-a)O 2 the “A-a gradient” Normal P(A-a)O 2 ranges from @ 5 to 25 mm Hg ORA (it increases with age) A higher than normal P(A-a)O 2 means the lungs are not transferring oxygen properly from alveoli into the pulmonary capillaries An ↑P(A-a)O 2 signifies a problem within the lungs Exception: right to left cardiac shunts

21 NON-RESPIRATORYP(A-a)O 2 Cardiac right to left shuntIncreased Decreased PIO 2 Normal Low mixed venous oxygen content*Increased RESPIRATORY Pulmonary right to left shuntIncreased Ventilation-perfusion imbalanceIncreased Diffusion barrierIncreased Hypoventilation (increased PaCO 2 )Normal *Unlikely to be clinically significant unless there is right to left shunting or ventilation-perfusion imbalance

22 Ventilation-Perfusion imbalance A normal amount of ventilation-perfusion (V-Q) imbalance accounts for the normal P(A-a)O 2 By far the most common cause of low PaO 2 is an abnormal degree of ventilation-perfusion imbalance within the millions of alveolar-capillary units Virtually all lung disease lowers PaO 2 via V-Q imbalance i.e. asthma, pneumonia, atelectasis, pulm edema, COPD Diffusion barrier is seldom a major cause of low PaO 2 (it can lead to a low PaO 2 during exercise)

23 Case VQ Mis-Match

24 Case 34 Male presents with HA Working out of town – sleeping in the shop Awoken at 2-3am by an alarm but went back to sleep Found by his foreman at about 9am Drove back to Calgary but had difficulty staying awake

25 GAS Arterial Blood GasSerum ChemistriesOther Tests pH: 7.40 O 2 sat: 97% pO 2 : 80 mm Hg pCO 2 : 38 mm Hg [HCO 3 - ]: 24 mEq\L

26 How much oxygen is in the blood? PaO 2 vs. SaO 2 vs. CaO 2 OXYGEN PRESSURE: PaO 2 PaO 2 reflects only free oxygen molecules dissolved in plasma and not those bound to hemoglobin PaO 2 cannot tell us “how much” oxygen is in the blood OXYGEN SATURATION: SaO 2 The percentage of all the available heme binding sites saturated with oxygen is the hemoglobin oxygen saturation (in arterial blood, the SaO 2 ) How much hemoglobin is there? OXYGEN CONTENT: CaO 2 CaO 2 is the only value that incorporates the hemoglobin content (units ml O 2 /dl) Oxygen content can be measured directly or calculated by the oxygen content equation: CaO 2 = (Hb x 1.34 x SaO 2 ) + (.003 x PaO 2 )

27 Is pO2 the best measure of oxygenation in this case?

28 Case Continued Arterial Blood GasSerum ChemistriesOther Tests pH: 7.36 O 2 sat: 97% pO 2 : 79 mm Hg pCO 2 : 31 mm Hg SaO 2: 53% COHb: 46% [HCO 3 - ]: 24 mEq\L returned a few hours later with mental confusion this time both SaO 2 and COHb were measured

29 CO has a ‘double-whammy’ effect 1)decreases SaO 2 by the amount of COHb present 2)shifts the O 2 -dissociation curve to the left, retarding unloading of oxygen to the tissues CO does not affect PaO 2, only SaO 2 To detect CO poisoning, SaO 2 and/or COHb must be measured In the presence of excess CO, SaO 2 will be lower than expected from the PaO 2

30 Carbon Monoxide CO is colorless, odorless gas, a product of combustion; all smokers have excess CO in their blood, typically 5-10% CO binds 200x more avidly to hemoglobin than O 2, effectively displacing O 2 from the heme binding sites CO is a major cause of poisoning deaths world-wide Normal %COHb in the blood is 1-2%, from metabolism and small amount of ambient CO (higher in smokers and traffic-congested areas)

31 SaO 2 and CaO 2 : test your understanding Below are blood gas results from four pairs of patients. For each letter pair, state which patient, (1) or (2), is more hypoxemic. Units for hemoglobin content (Hb) are gm% and for PaO 2 mm Hg. a)(1)Hb 150, PaO 2 100, pH 7.40, COHb 20% (2)Hb 120, PaO 2 100, pH 7.40, COHb 0 b)(1)Hb 150, PaO 2 90, pH 7.20, COHb 5% (2)Hb 150, PaO 2 50, pH 7.40, COHb 0

32 SaO 2 and CaO 2 : test your understanding Answers a)(1) CaO 2 =.78 x 15 x 1.34 = 15.7 ml O 2 /dl (2) CaO 2 =.98 x 12 x 1.34 = 15.8 ml O 2 /dl The oxygen contents are almost identical, and therefore neither patient is more hypoxemic. However, patient (1), with 20% CO, is more hypoxic than patient (2) because of the left-shift of the O 2 - dissociation curve caused by the CO b)(1) CaO 2 =.87 x 15 x 1.34 = 17.5 ml O 2 /dl (2) CaO 2 =.85 x 15 x 1.34 = 17.1 ml O 2 /dl A PaO 2 of 90 mm Hg with pH of 7.20 gives an SaO 2 of @ 92%; subtracting 5% COHb from this value gives a true SaO 2 of 87%, used in the CaO 2 calculation of patient (1). A PaO 2 of 50 mm Hg with normal pH gives an SaO 2 of 85%. Thus patient (2) is slightly more hypoxemic.

33

34 Acid-Base Normal serum pH is between 7.36-7.44 A pH outside 6.8 – 7.8 is incompatible with life pH is maintained by 3 systems 1)Physiologic buffers 2)Lungs 3)Kidneys Disorders in any of these systems leads to alterations in blood pH

35 Methanol poisoning example

36 Physiologic Buffers 1) Bicarbonate-carbonic acid H + + HCO 3 - ↔ H 2 CO 3 ↔ H 2 O + CO 2 2) Blood protein buffers Hemoglobin 3) Bone Reservoir of bicarb and phosphate

37 Lungs ∆ pH sensed by peripheral and central chemoreceptors Peripherally (carotid bodies) Centrally (medulla oblongata) ↓ pH Increased minute ventilation Lowers PaCO 2 ↑ pH Decreased ventilatory effort Increases PaCO 2

38 Kidneys Not involved in acute compensation After 6hrs of Alkalemia Excretion of HCO 3 - Retention of H + 6-12hrs Acidosis Excretion of H + Retention of HCO 3 -

39 Terminology Acidemia: blood pH < 7.35 Acidosis: a physiologic process that, occurring alone, tends to cause acidemia e.g.: metabolic acidosis from decreased perfusion (lactic acidosis); respiratory acidosis from hypoventilation If the patient also has an alkalosis at the same time, the resulting blood pH may be low, normal or high

40 Terminology Alkalemia: blood pH > 7.45 Alkalosis: a primary physiologic process that, occurring alone, tends to cause alkalemia i.e.: metabolic alkalosis from excessive diuretic therapy; respiratory alkalosis from acute hyperventilation If the patient also has an acidosis at the same time, the resulting blood pH may be high, normal or low.

41 Terminology Primary acid-base disorder: One of the four acid-base disturbances that is manifested by an initial change in HCO 3 - or PaCO 2. Compensation: The change in HCO 3 - or PaCO 2 that results from the primary event. Compensatory changes are not classified by the terms used for the four primary acid-base disturbances. i.e. a patient who hyperventilates (lowers PaCO 2 ) solely as compensation for MAc does not have a RAlk, the latter being a primary disorder that, alone, would lead to alkalemia. In simple, uncomplicated MAc the patient will never develop alkalemia.

42 [ H+ ] x [ HCO3- ]k1 x H2CO3k2 x [ CO2 ] x [ H2O ] [ H+ ] x [ HCO3- ] [ HCO3- ][ H+ ] X Henderson without Hassel(balch) X

43 Henderson without the Hassel(balch) [ H+ ] [ HCO 3 - ] [CO 2 ]

44 Henderson-Hasselbach Henderson's equation shows the relationship between [H+], [HCO3-], and PCO2 It performs the same function as the more Henderson-Hasselbalch Equation

45 Acid-Base Disorders Respiratory disorders Alter the serum PaCO 2 Metabolic disorders Alter the serum HCO 3 - Thanks Marc!

46 Respiratory Disorders ACIDOSIS Hypoventilation Pulmonary pathology Airway obstruction Decreased respiratory drive ALKALOSIS Hyperventilation CNS disease Hypoxemia Anxiety Toxic states Hepatic insufficiency Assisted ventilation Thanks Marc!

47 Metabolic Disorders ACIDOSIS 1)Wide gap metabolic acidosis 2)Non-AG metabolic acidosis ALKALOSIS 1)Saline responsive 2)Saline resistant Thanks Marc!

48 Anion Gap Metabolic Acidosis Addition of Acids or Creation of Acids CATMUDPILES Carbon monoxide/cyanide Alcohol/AKA Toluene Methanol Uremia DKA Paraldehyde INH/Iron Lactic Acidosis Ethylene glycol Salicylates Thanks Marc!

49 Normal AG Metabolic Acidosis Excessive loss of HCO 3 - OR Inability to excrete H + HARD UPS Hyperalimentation/Hyperventilation Acids/Addison’s/Acetazolamide RTA Diarrhea/Dehydration/ Diuretics Uterosigmoidostomy Pancreatic fistula or drainage Saline (large amounts) Thanks Marc!

50 Metabolic Alkalosis Saline Responsive Vomit → lose HCl Kidneys try to hang on to H+ …excrete Na+ instead Until, dehydration kicks in → Renin/Aldo If we rehydrate we allow the kidneys to work

51 Saline Responsive Vomiting/Gastric Suction Diuretics Ion-deficient baby formula Colonic adenomas (HCl) Saline shuts off Renin/Angiotensin/Aldo

52 Saline Non-Responsive Higher up in the cascade Primary aldosteronism Exogenous steroids Adenocarcinoma Bartter’s Syndrome Cushing’s disease Ectopic ACTH

53 Mixed Acid-Base Disorders In chronically ill respiratory patients In renal failure

54 Metabolic Compensation for Respiratory Disorders CompensationPaCO 2 : HCO 3 - Acute Resp Acidosis10:1 Acute Resp Alkalosis10:2 Chronic Resp Acidosis10:3 Chronic Resp Alkalosis10:4

55 Respiratory Compensation for Metabolic Disorders CompensationPaCO 2 : HCO 3 - Metabolic Acidosis1:1 Metabolic Alkalosis1: 0.75

56 “The Corey Slovis approach to acid-base abnormalities” Thanks again Marc!

57 Slovis 6-step approach to ABG 1)Check the numbers 2)Apply the ABG rules 3)Calculate the AG 4)If Acidosis apply the rule of 15 (+/- 2) 5)If Acidosis apply the delta gap (+/- 4) 6)Check the osmolar gap

58 Check the numbers Know your normal values Does the blood gas make sense? Are there any immediate hints to the diagnosis

59 The ABG rules 1) Is it an Acidosis or Alkalosis Look at the pH 2) Is it Respiratory or Metabolic Metabolic = pCO 2 + pH ∆ in same direction Resp = pCO 2 + pH ∆ in opposite direction 3) Is it a pure respiratory acidosis? ↑pCO 2 : ↓pH = 1:1

60 Calculate the AG Na – [HCO 3 + Cl] Normal = 5-12 Upper limit of normal is 15

61 What is the Anion Gap?

62 Na+ Cl- HCO3- K+ Acetate Hipurate Mg++ Ca++ Lactate

63 What elevates the Gap? Na+ Cl- HCO3- K+ Acetate HipurateMg++Ca++ Lactate

64 What lowers the Gap? Na+ Cl- HCO3- K+ Mg++ Ca++ Lactate lithium

65 Our blood is neutral ↑AG = unmeasured cations ↓AG = unmeasured anions

66 Rule of 15 HCO 3 + 15 = pCO 2 and pH (last 2 digits) Used in acidosis Derived from Henderson Hasselbalch equation It predicts what resp compensation will do to the pCO 2 and the pH If the Rule is broken then another process other than just resp compensation exists

67 Rule of 15 Creates a new set point for the pCO 2 pCO 2 appropriate = normal compensation pCO 2 too low = superimposed primary resp alkalosis pCO 2 too high = superimposed primary resp acidosis Note: as HCO 3 falls below 10 you need to use the formula HCO 3 x 1.5 + 8 = expected pCO 2

68 Examples of rule of 15 1) HCO 3 =20, pCO 2 =35 pH= 7.35 Pure wide gap metabolic acidosis with an appropriate 2ndary resp alkalosis 2) HCO 3 =10, pCO 2 =20 pH= 7.32 pCO 2 is too low. Superimposed primary resp alkalosis 3) HCO 3 =10, pCO 2 =32 pH= 7.14 pCO 2 is too high. Superimposed primary resp acidosis

69 Delta Gap Checks for “hidden” metabolic process Based on the 1:1 concept that ↑AG = ↓HCO 3 Upper limit of AG = 15 Normal HCO 3 = 24 Bicarb too high = metabolic alkalosis Bicarb too low = Non-gap metabolic acidosis

70 What is the Delta Gap? Looks for other metabolic processes in an elevated AG acidosis What happens in an isolated AG acidosis?

71 Acid is added → Anion + H + H+ + HCO3- ↔ H2CO3 ↔ H2O + CO2 → Anion + H2O + CO2 ↑AG = ↓HCO 3

72 Bicarb too high = metabolic alkalosis Bicarb too low = Non-gap metabolic acidosis

73 Examples of delta gap AG=22 HCO 3 =17 ∆AG = 7 and ∆HCO 3 = 7 No hidden process AG=24 HCO 3 =8 ∆AG = 9 and ∆HCO 3 = 16 Bicarb too low = additional non-gap MAc AG=28 HCO 3 =20 ∆AG = 13 and ∆HCO 3 = 4 Bicarb too high = additional MAlk

74 Osmolar Gap 2Na + BUN + Glucose = calculated gap OG = Measured – calculated Upper limit of normal is ~10 If higher consider toxic alcohols Remember with EtOH 2Na + BUN + Glucose + [1.25 x EtOH]

75 Case 1 20 F presents with lethargy, polydipsia and polyuria Arterial Blood GasLytesUrine Tests pH: 7.24Na + : 130 mEq/LpH: 5.0 pCO 2 : 24 mm HgK + : 4.5 mEq/L HCO 3 - : 10 mEq/LCl - : 94 mEq/L Glucose: 32

76 Approach 1)Check the numbers 2)Apply the ABG rules 3)Calculate the AG 4)If Acidosis apply the rule of 15 (+/- 2) 5)If Acidosis apply the delta gap (+/- 4) 6)Check the osmolar gap

77 Case 2 43 F known diabetic, asymptomatic, managed with Glyburide. FHx of HTN. No personal Hx of HTN. OE: 180/100 Arterial Blood GasLytesUrine Tests pH: 7.49Na + : 142 mEq/LpH: 6.5 pCO 2 : 45 mm HgK + : 4.5 mEq/L HCO 3 - : 33 mEq/LCl - : 98 mEq/L Cr: 110 BUN: 14 mg/dL

78 Approach 1)Check the numbers 2)Apply the ABG rules 3)Calculate the AG 4)If Acidosis apply the rule of 15 (+/- 2) 5)If Acidosis apply the delta gap (+/- 4) 6)Check the osmolar gap

79 Case 3 22 M with a Hx of nephrolithiasis. Arterial Blood GasLytesUrine Tests pH: 7.29Na + : 138 mEq/LpH: 6.0 pCO 2 : 32 mm HgK + : 3.0 mEq/LNa + : 35 mEq/L HCO 3 - : 15 mEq/LCl - : 110 mEq/LK + : 45 mEq/L Cl - : 75 mEq/L

80 Approach 1)Check the numbers 2)Apply the ABG rules 3)Calculate the AG 4)If Acidosis apply the rule of 15 (+/- 2) 5)If Acidosis apply the delta gap (+/- 4) 6)Check the osmolar gap

81 Case 4 Case 4a. 72 F with a brain tumor (dx in April ’07), presents with an acute change in mental status. Presently comatose with Kussmals respirations. CT HEAD: Intracerebral Hemorrhage with shift! Arterial Blood GasLytesUrine Tests pH: 7.57Na + : 136 mEq/LpH: 7.0 pCO 2 : 20 mm HgK + : 4.0 mEq/L HCO 3 - : 18 mEq/LCl - : 103 mEq/L

82 Approach 1)Check the numbers 2)Apply the ABG rules 3)Calculate the AG 4)If Acidosis apply the rule of 15 (+/- 2) 5)If Acidosis apply the delta gap (+/- 4) 6)Check the osmolar gap

83 Case 5 A 20-year-old man is brought to the emergency room by his sister, who tells you he took a bottle of pills. Arterial Blood GasSerum ChemistriesUrine Tests pH: 7.35[Na + ]: 140 mEq/LpH: 5.0 pCO 2 : 15 mm Hg[K + ]: 3.5 mEq/L [HCO 3 - ]: 8 mEq\L[Cl - ]: 104 mEq/L

84 Approach 1)Check the numbers 2)Apply the ABG rules 3)Calculate the AG 4)If Acidosis apply the rule of 15 (+/- 2) 5)If Acidosis apply the delta gap (+/- 4) 6)Check the osmolar gap

85 Case 6 Case 6a: A 57-year-old patient with a long history of smoking presents to you in no distress, but he tells you he develops dyspnea on exertion. You send him for pulmonary function tests (PFTs) and an arterial blood gas (ABG). Arterial Blood GasSerum ChemistriesUrine Tests pH: 7.35[Na + ]: 143 mEq/LpH: 5.0 pCO 2 : 50 mm Hg[Cl - ]: 105 mEq/L [HCO 3 - ]: 27 mEq\L

86 Approach 1)Check the numbers 2)Apply the ABG rules 3)Calculate the AG 4)If Acidosis apply the rule of 15 (+/- 2) 5)If Acidosis apply the delta gap (+/- 4) 6)Check the osmolar gap

87 Case 6b Case 6b: The patient in Case 6a presents to the emergency room again 1 month later in respiratory distress. He is wheezing and his respiratory rate is 33 breaths/minute. Arterial Blood GasSerum ChemistriesUrine Tests pH: 7.29[Na + ]: 142 mEq/LpH: 5.0 pCO 2 : 61 mm Hg[Cl - ]: 100 mEq/L [HCO 3 - ]: 29 mEq\L

88 Approach 1)Check the numbers 2)Apply the ABG rules 3)Calculate the AG 4)If Acidosis apply the rule of 15 (+/- 2) 5)If Acidosis apply the delta gap (+/- 4) 6)Check the osmolar gap

89 Case 7 Case 7: A 45-year-old diabetic patient presents with obtundation. Arterial Blood GasSerum ChemistriesUrine Tests pH: 7.01[Na + ]: 138 mEq/LpH: 5.0 pCO 2 : 70 mm Hg[K + ]: 5.5 mEq/L [HCO 3 - ]: 18 mEq\L[Cl - ]: 97 mEq/L

90 Approach 1)Check the numbers 2)Apply the ABG rules 3)Calculate the AG 4)If Acidosis apply the rule of 15 (+/- 2) 5)If Acidosis apply the delta gap (+/- 4) 6)Check the osmolar gap

91 Case 8 A 78-year-old nursing home patient has been vomiting for several days and has rapidly developed a fever and increasing shortness of breath over the past several hours. Her respiratory rate is 35 breaths/minute, and she has consolidative signs in the right base of the lung. Arterial Blood GasSerum ChemistriesUrine Tests pH: 7.69[Na + ]: 138 mEq/LpH: 8.0 pCO 2 : 20 mm Hg[Cl - ]: 97 mEq/L [HCO 3 - ]: 28 mEq\L

92 Approach 1)Check the numbers 2)Apply the ABG rules 3)Calculate the AG 4)If Acidosis apply the rule of 15 (+/- 2) 5)If Acidosis apply the delta gap (+/- 4) 6)Check the osmolar gap

93 Case 9 A 20-year-old diabetic patient presents with nausea and vomiting for several days, and with fever and shortness of breath that have developed over the past 8 hours. Arterial Blood GasSerum ChemistriesUrine Tests pH: 7.59[Na + ]: 140 mEq/LpH: 8.0 pCO 2 : 25 mm Hg[Cl - ]: 95 mEq/LKetones: postive [HCO 3 - ]: 24 mEq\L[Glucose]: 34 BUN: 9.3

94 Approach 1)Check the numbers 2)Apply the ABG rules 3)Calculate the AG 4)If Acidosis apply the rule of 15 (+/- 2) 5)If Acidosis apply the delta gap (+/- 4) 6)Check the osmolar gap

95 Case 10 A 47-year-old man with alcoholism presents with vomiting after binge drinking for the past 2 days. He is brought to the emergency room by his friend, who tells you he took a large number of diazepam pills 1 hour prior and became “very sleepy”. His respiratory rate is 8 breaths/minute and he is unresponsive. Arterial Blood GasSerum ChemistriesUrine Tests pH: 7.27[Na + ]: 135 mEq/LpH: 5.0 pCO 2 : 62 mm Hg[Cl - ]: 85 mEq/L [HCO 3 - ]: 28 mEq\LBUN: 7.5

96 Approach 1)Check the numbers 2)Apply the ABG rules 3)Calculate the AG 4)If Acidosis apply the rule of 15 (+/- 2) 5)If Acidosis apply the delta gap (+/- 4) 6)Check the osmolar gap

97 Case 11 A 65-year-old man with chronic obstructive pulmonary disease (COPD) and congestive heart failure (CHF) presents with increasing shortness of breath and wheezing for the past 4 hours. He is currently on furosemide. Arterial Blood GasSerum ChemistriesUrine Tests pH: 7.40[Na + ]: 140 mEq/LpH: 5.0 pCO 2 : 60 mm Hg[Cl - ]: 90 mEq/L [HCO 3 - ]: 37 mEq\L

98 Approach 1)Check the numbers 2)Apply the ABG rules 3)Calculate the AG 4)If Acidosis apply the rule of 15 (+/- 2) 5)If Acidosis apply the delta gap (+/- 4) 6)Check the osmolar gap

99 Case 12 A 27-year-old diabetic patient presents with 1 hour of acute shortness of breath. He has been nauseated and has had increased urination over the past 2 days. Because of his nausea, he decided not to take his insulin and has been bedridden the past 2 days. In the emergency room, you discover he has a family history of hypercoagulable disorder. Arterial Blood GasSerum ChemistriesUrine Tests pH: 7.40[Na + ]: 140 mEq/LpH: 5.0 pCO 2 : 20 mm Hg[Cl - ]: 102 mEq/LKetones: positive [HCO 3 - ]: 12 mEq\L[Glucose]: 35

100 Approach 1)Check the numbers 2)Apply the ABG rules 3)Calculate the AG 4)If Acidosis apply the rule of 15 (+/- 2) 5)If Acidosis apply the delta gap (+/- 4) 6)Check the osmolar gap

101 Case 13 You receive a 67 M with post polio lung disease in handover. He presents to the ER with increased WOB and decreased LOC. Been in the department for some time. Arterial Blood GasSerum ChemistriesUrine Tests pH: 7.60 pCO 2 : 40 mm Hg pO2: 60 mm Hg Sat 90% [HCO 3 - ]: 30 mEq\L

102 Thanks!