Acid-base questions Charles J. Foulks, M.D., FACP Professor of Medicine October 12, 2011

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

 Is there compensation?  NO  What is the primary acid-base disturbance and its etiology?  DIABETIC KETOACIDOSIS.  If there wasn’t compensation, what is the other primary disorder?  PRIMARY RESPIRATORY ACIDOSIS  What is the anion gap?  26  Is there compensation?  YES

A 67 yo man is 12 hours post-operatively from coronary artery bypass grafting. A 67 yo man is 12 hours post-operatively from coronary artery bypass grafting. While being extubated, he aspirated, became septic, and 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 7.14torr, pCO2 12. While being extubated, he aspirated, became septic, and 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 7.14torr, pCO2 12.  What is the primary acid-base disorder and its etiology?  LACTIC ACIDOSIS SECONDARY TO EITHER SHOCK OR SEPSIS.  Is there compensation?  YES.  What is the anion gap?  43

4. A 23 yo woman was admitted with nausea and vomiting for several days. Intake has been poor. Na 128 mEq/L, Cl 80 mEq/L, K 2.9 mEq/L, HCO3 32 mEq/L, pCO2 44 torr, pH A 23 yo woman was admitted with nausea and vomiting for several days. Intake has been poor. Na 128 mEq/L, Cl 80 mEq/L, K 2.9 mEq/L, HCO3 32 mEq/L, pCO2 44 torr, pH What is the primary acid-base disorder and its etiology? What is the primary acid-base disorder and its etiology?  PRIMARY METABOLIC ALKALOSIS SECONDARY TO VOMITING.  Is there compensation?  Yes

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

 What was the initial acid-base disturbance and its etiology?  PRIMARY METABOLIC ALKALOSIS SECONDARY TO NASOGASTRIC SUCTION.  Was there compensation?  NO  If there wasn’t compensation, what is the other primary disorder?  PRIMARY RESPIRATORY ACIDOSIS.

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

What is the primary acid-base disturbance and its etiology? What is the primary acid-base disturbance and its etiology?  PRIMARY METABOLIC ACIDOSIS SECONDARY TO EITHER METHANOL OR ETHYLENE 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?  THERE ARE TWO PRIMARY DISORDERS. EITHER CAN BE THE ANSWER HERE: PRIMARY METABOLIC ALKALOSIS (FROM NG SUCTIONING) OR PRIMARY RESPIRATORY ALKALOSIS (FROM PAIN).  Was there compensation:  NO

CASE 1 CASE 1 Objective: 1. Recognize data base items needed to diagnose and treat acid base abnormalities. Objective: 1. Recognize data base items needed to diagnose and treat acid base abnormalities. An asymptomatic patient is found to have the following laboratory values: An asymptomatic patient is found to have the following laboratory values: Na+ 138 mEq/L Cl- 112 mEq/L Na+ 138 mEq/L Cl- 112 mEq/L K+ 3.9 mEq/L HCO3- 14 mEq/L K+ 3.9 mEq/L HCO3- 14 mEq/L Intravenous NaHCO3 is infused to raise the plasma HCO3- concentration. Is this the correct form of therapy? Intravenous NaHCO3 is infused to raise the plasma HCO3- concentration. Is this the correct form of therapy?

CASE 2 Objectives: 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 pCO 2 37 torr HCO 3 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 , 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, fever, prod cough 85 yo male presents to ED with pneumonia, fever, prod cough Mod distress, 120/86, 74, 24, Mod distress, 120/86, 74, 24, Dec. breath sounds, L base Dec. breath sounds, L base Na 120 K 3.9 Cl 87 Bicarb 24 Na 120 K 3.9 Cl 87 Bicarb 24 Bun 10 Creat 0.8 Glu 90 Bun 10 Creat 0.8 Glu 90 Urine Na 60, K+ 30, Osmolality 500 Urine 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 vomiting over 4 days. BP 100/70, P 120, light headed. 44 yo man, hx chronic pancreatitis, adm for vomiting over 4 days. BP 100/70, P 120, light headed. What disorders do you predict? What disorders do you predict?  Na+  K+  Acid-base  Answers?

Hard Problems 54 yo female, cerv ca 20 years ago, rec. external beam irradiation. Has HTN, chronic kidney disease, weight loss over several months. Presents to ED with c/o severe dyspnea, RR 40, shallow. 54 yo female, cerv ca 20 years ago, rec. external beam irradiation. Has HTN, chronic kidney disease, weight loss over several months. Presents to ED with c/o 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 had spasm of her R had when BP taken RN tells you she can’t lift her head and she had spasm of her R had when BP taken

Hard Problems Exam: strength 0-1+/5, clear chest, no S3, loss of muscle mass in hands, cheeks, hair pulls out easily, loss of lunulae, tongue pale You repeat the BP and she has spasm of that hand. Lab?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%, mcv 70, pH 6.94 Ca 4.4 mg/dL, alb 3.0, Mg++ 0.8, hct 24%, mcv 70, pH 6.94 Predict the QT interval Predict the QT interval Why? Why? How to fix? How to fix?

Hard Cases 5 mo old male, normal birth, brought in by mom for lethargy. No fever, cough. Wets diapers, has been fussy for 5-6 days. 5 mo old male, normal birth, brought in by mom for lethargy. No fever, cough. Wets diapers, has been fussy for 5-6 days. Lethargic child, but not limp. BP 98/70, looks fat. Temp Remainder of exam totally normal. LP negative. No evidence of trauma. No focal findings Lethargic child, but not limp. BP 98/70, looks fat. Temp Remainder of exam totally normal. LP negative. No evidence of trauma. 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?