Acid-base questions

Charles J. Foulks, M.D., FACPCharles J. Foulks, M.D., FACP

Professor of MedicineProfessor of Medicine

October 12, 2011October 12, 2011

A 16 yo type I diabetic is admitted to the A 16 yo type I diabetic is admitted to the ICU. Serum ketones are positive, glucose is ICU. Serum ketones are positive, glucose is 394 mg/dL, Na 134 mEq/L, K 5.2 mEq/L, 394 mg/dL, Na 134 mEq/L, K 5.2 mEq/L, Cl 98 mEq/L, HCO3 10 mEq/L, pH 7.17, Cl 98 mEq/L, HCO3 10 mEq/L, pH 7.17, pCO2 is 28 torr.pCO2 is 28 torr.

Is there compensation? Is there compensation? NONO

What is the primary acid-base disturbance and its What is the primary acid-base disturbance and its etiology? etiology?

DIABETIC KETOACIDOSIS.DIABETIC KETOACIDOSIS. If there wasn’t compensation, what is the other primary If there wasn’t compensation, what is the other primary

disorder? disorder? PRIMARY RESPIRATORY ACIDOSISPRIMARY RESPIRATORY ACIDOSIS

What is the anion gap?What is the anion gap? 2626

Is there compensation? Is there compensation? YESYES

A 67 yo man is 12 hours post-operatively from coronary A 67 yo man is 12 hours post-operatively from coronary artery bypass grafting. artery bypass grafting.

While being extubated, he aspirated, became septic, and While being extubated, he aspirated, became septic, and developed shock. His BP is 80/50 mm Hg. on multiple developed shock. His BP is 80/50 mm Hg. on multiple pressors. Na 145 mEq/L, Cl 98 mEq/L, K 4 mEq/L, ph pressors. Na 145 mEq/L, Cl 98 mEq/L, K 4 mEq/L, ph 7.14torr, pCO2 12.7.14torr, pCO2 12.

What is the primary acid-base disorder and its etiology?What is the primary acid-base disorder and its etiology? LACTIC ACIDOSIS SECONDARY TO EITHER LACTIC ACIDOSIS SECONDARY TO EITHER

SHOCK OR SEPSIS.SHOCK OR SEPSIS. Is there compensation? Is there compensation?

YES.YES. What is the anion gap? What is the anion gap?

4343

4. A 23 yo woman was admitted with nausea and 4. A 23 yo woman was admitted with nausea and vomiting for several days. Intake has been poor. vomiting for several days. Intake has been poor. Na 128 mEq/L, Cl 80 mEq/L, K 2.9 mEq/L, Na 128 mEq/L, Cl 80 mEq/L, K 2.9 mEq/L, HCO3 32 mEq/L, pCO2 44 torr, pH 7.47.HCO3 32 mEq/L, pCO2 44 torr, pH 7.47.

What is the primary acid-base disorder and its What is the primary acid-base disorder and its etiology? etiology?

PRIMARY METABOLIC ALKALOSIS PRIMARY METABOLIC ALKALOSIS SECONDARY TO VOMITING.SECONDARY TO VOMITING.

Is there compensation?Is there compensation?YesYes

5. A 60 yo male with chronic obstructive 5. A 60 yo male with chronic obstructive pulmonary disease has been on naso-pulmonary disease has been on naso-gastric suction for 3 days. You have been gastric suction for 3 days. You have been asked to see him for a diagnosis of asked to see him for a diagnosis of lethargy. Labs Na 142 mEq/L, Cl 88 lethargy. Labs Na 142 mEq/L, Cl 88 mEq/L, k 2.8 mEq/L, HCO3 40 mEq/L, mEq/L, k 2.8 mEq/L, HCO3 40 mEq/L, pCO2 62 torr, pH 7.42. pCO2 62 torr, pH 7.42.

What was the initial acid-base What was the initial acid-base disturbance and its etiology? disturbance and its etiology? PRIMARY METABOLIC PRIMARY METABOLIC

ALKALOSIS SECONDARY TO ALKALOSIS SECONDARY TO NASOGASTRIC SUCTION.NASOGASTRIC SUCTION.

Was there compensation? Was there compensation? NONO

If there wasn’t compensation, what is the If there wasn’t compensation, what is the other primary disorder? other primary disorder? PRIMARY RESPIRATORY PRIMARY RESPIRATORY

ACIDOSIS.ACIDOSIS.

A 32 yo male was found comatose at home A 32 yo male was found comatose at home in his garage. He is a known heavy drinker. in his garage. He is a known heavy drinker. Lab values Na 138 mEq/L, Cl 96 mEq/L, K Lab values Na 138 mEq/L, Cl 96 mEq/L, K 3.2 mEq/L, HCO3 4 mEq/L, pCO2 16 torr, 3.2 mEq/L, HCO3 4 mEq/L, pCO2 16 torr, pH 7.00, BUN 20 mg/dL, glucose 122, pH 7.00, BUN 20 mg/dL, glucose 122, serum osmolarity 363 mosm/kg. serum osmolarity 363 mosm/kg.

What is the primary acid-base disturbance What is the primary acid-base disturbance and its etiology? and its etiology? PRIMARY METABOLIC ACIDOSIS PRIMARY METABOLIC ACIDOSIS

SECONDARY TO EITHER SECONDARY TO EITHER METHANOL OR ETHYLENE METHANOL OR ETHYLENE GLYCOL POISONING. GLYCOL POISONING.

Was there compensation? Was there compensation? YES.YES.

A46 yo male has undergone bowel resection for Crohn’s disease. He is now 5 days post-operative and is on nasogastric suction. Lab values Na 132 mEq/L, HCO3 26 mEq/L, pCO2 32 torr, pH 7.50.

What is the primary acid-base disturbance? What is the primary acid-base disturbance? THERE ARE TWO PRIMARY THERE ARE TWO PRIMARY

DISORDERS. EITHER CAN BE THE DISORDERS. EITHER CAN BE THE ANSWER HERE: PRIMARY ANSWER HERE: PRIMARY METABOLIC ALKALOSIS (FROM NG METABOLIC ALKALOSIS (FROM NG SUCTIONING) OR PRIMARY SUCTIONING) OR PRIMARY RESPIRATORY ALKALOSIS (FROM RESPIRATORY ALKALOSIS (FROM PAIN).PAIN).

Was there compensation: Was there compensation: NONO

  CASE 1CASE 1 Objective: 1. Recognize data base items needed to Objective: 1. Recognize data base items needed to

diagnose and treat acid base abnormalities.diagnose and treat acid base abnormalities. An asymptomatic patient is found to have the following An asymptomatic patient is found to have the following

laboratory values:            laboratory values:                                    Na+     138 mEq/L              Cl-        112 mEq/LNa+     138 mEq/L              Cl-        112 mEq/L                         K+      3.9 mEq/L              HCO3-  14 mEq/LK+      3.9 mEq/L              HCO3-  14 mEq/L Intravenous NaHCO3 is infused to raise the plasma Intravenous NaHCO3 is infused to raise the plasma

HCO3- concentration. Is this the correct form of therapy?HCO3- concentration. Is this the correct form of therapy?

CASE 2Objectives:       1. To diagnose an acid base disorder given necessary data. 2. To recognize this acid base disorder. A 64 year old disoriented woman is brought to the emergency room. No history is obtainable. She is tachypneic (respiratory rate 35/min) and confused, but physical examination is otherwise not remarkable. Laboratory studies include: Na+ 144 mEq/L  Arterial blood  pH 7.24   K+ 4.4 mEq/L    HCO3 9 mEq/L Cl- 107 mEq/L      pCO2    22 mmHg

 

1. What is her acid base abnormality?2. What are the possible causes? She has a normal serum creatinine concentration and plasma ketone level which is undetectable.3. What diagnoses are now plausible?4. What additional tests might you order to establish to correct diagnosis?5. What if her pCO2 were 16 torr?

            CASE 3

Objectives:  1. To review acid/base abnormalities with GI fluid loss.                      2. To calculate blood gas data. A 70 year old man has had repeated diarrheal stools for the past 3 days. Blood studies include:Na+      132 mEq/L         Arterial  pH   7.39 K+        2.7 mEq/L         HCO3 22 mEq/L Cl- 90 mEq/L pCO2 37 torrHCO3 9 mEq/L

  CASE 4

Objective: To recognize this acid base disturbance - its generation, maintenance, and therapy.

A 50 year old man is more successful as a lawyer than as a husband. His recent divorce and the financial settlement have pushed his cigarette and Cutty Sark consumption to unreasonable levels, and flared his long-standing peptic ulcer disease. "Doc, I've about had it. I've been vomiting for four days". You admit him to the hospital. His BP is 110/70, falling to 70/60 when he sits up. Resting pulse rate is 98/min. Skin turgor is poor, and he has obviously lost weight.

His Hct is 46%, BUN 28 mg/dl, serum creatinine 1.4 mg/dl. Urinalysis shows S.G. 1.028, no protein, and a normal sediment. Other laboratory studies include:

 Na+    135  mEq/L            arterial  pH   7.60   K+     3.0 mEq/L                    HCO3    42 nEq/L            Cl-       83 mEq/L                    pCO2  42 torr                             

 

Hyponatremia

85 yo male presents to ED with pneumonia, 85 yo male presents to ED with pneumonia, fever, prod coughfever, prod cough

Mod distress, 120/86, 74, 24, 101.8Mod distress, 120/86, 74, 24, 101.8 Dec. breath sounds, L baseDec. breath sounds, L base Na 120 K 3.9 Cl 87 Bicarb 24Na 120 K 3.9 Cl 87 Bicarb 24 Bun 10 Creat 0.8 Glu 90Bun 10 Creat 0.8 Glu 90 Urine Na 60, K+ 30, Osmolality 500Urine Na 60, K+ 30, Osmolality 500

Hyponatremia

1. What is hyponatremia?1. What is hyponatremia? 2. Is it synonymous with hypo-osmolality?2. Is it synonymous with hypo-osmolality? 3. What is the calc osm?3. What is the calc osm?

4. What is pseudohyponatremia?4. What is pseudohyponatremia?

5. Cause of his hyponatremia?5. Cause of his hyponatremia?

6. Why?6. Why?

Hard Problems

44 yo man, hx chronic pancreatitis, adm for 44 yo man, hx chronic pancreatitis, adm for vomiting over 4 days. BP 100/70, P 120, light vomiting over 4 days. BP 100/70, P 120, light headed.headed.

What disorders do you predict?What disorders do you predict? Na+Na+ K+K+ Acid-baseAcid-base Answers?Answers?

Hard Problems

54 yo female, cerv ca 20 years ago, rec. 54 yo female, cerv ca 20 years ago, rec. external beam irradiation. Has HTN, external beam irradiation. Has HTN, chronic kidney disease, weight loss over chronic kidney disease, weight loss over several months. Presents to ED with c/o several months. Presents to ED with c/o severe dyspnea, RR 40, shallow.severe dyspnea, RR 40, shallow.

Exam: 88/60, 130, 40, 97.7, O2 sat 96%Exam: 88/60, 130, 40, 97.7, O2 sat 96% RN tells you she can’t lift her head and she RN tells you she can’t lift her head and she

had spasm of her R had when BP takenhad spasm of her R had when BP taken

Hard Problems

Exam: strength 0-1+/5, clear chest, no S3, Exam: strength 0-1+/5, clear chest, no S3, loss of muscle mass in hands, cheeks, hair loss of muscle mass in hands, cheeks, hair pulls out easily, loss of lunulae, tongue palepulls out easily, loss of lunulae, tongue pale

You repeat the BP and she has spasm of that You repeat the BP and she has spasm of that hand.hand.

Lab?Lab?

Diagnoses?Diagnoses?

Hard Cases

Na 122, K 1.4, Cl 86, Bicarb 12, Phos 0.6,Na 122, K 1.4, Cl 86, Bicarb 12, Phos 0.6, Ca 4.4 mg/dL, alb 3.0, Mg++ 0.8, hct 24%, Ca 4.4 mg/dL, alb 3.0, Mg++ 0.8, hct 24%,

mcv 70, pH 6.94mcv 70, pH 6.94 Predict the QT intervalPredict the QT interval Why?Why? How to fix?How to fix?

Hard Cases

5 mo old male, normal birth, brought in by 5 mo old male, normal birth, brought in by mom for lethargy. No fever, cough. Wets mom for lethargy. No fever, cough. Wets diapers, has been fussy for 5-6 days.diapers, has been fussy for 5-6 days.

Lethargic child, but not limp. BP 98/70, Lethargic child, but not limp. BP 98/70, looks fat. Temp 98.4. Remainder of exam looks fat. Temp 98.4. Remainder of exam totally normal. LP negative. No evidence of totally normal. LP negative. No evidence of trauma. No focal findingstrauma. No focal findings

Hard Cases

What lab tests do you want and why?What lab tests do you want and why? Any more history needed?Any more history needed?