acid base cases amuthavalli

Cases on acid base balanceDr.V.Amuthavalli : 

Cases on acid base balanceDr.V.Amuthavalli

Case 1 : 

Case 1 A 22 year old female with type I DM, presents to the emergency department with a 1 day history of nausea, vomiting, polyuria, polydypsia and vague abdominal pain. P.E. noted for deep sighing breathing, orthostatic hypotension, and dry mucous membranes. Labs: Na 132 , K 6.0, Cl 93, HCO3- 11 glucose 720, BUN 38, Cr 2.6. UA: pH 5 , SG 1.010, ketones negative, glucose positive . Plasma ketones trace. ABG: pH 7.27 HCO3- 10  PCO2 23 the acid base disorder : Elevated anion gap acidosis secondary to DKA, or Elevated anion gap acidosis secondary to lactic acidosis in the setting of vomiting and polyuria which may lead to hypovolemia, and/or Metabolic alkalosis in the setting of vomiting The pH is low, (less than 7.35) therefore by definition, patient is acidemic. 3. What is the process? Look at the PCO2, HCO3- .     PCO2 and HCO3- are abnormal in the same direction, therefore less likely a mixed acid base disorder but not yet ruled out.

Case 1 contd : 

Case 1 contd low HCO3- represents acidosis and is consistent with the pH, therefore it must be the initial change. To maintain the PCO2/HCO3-, the PCO2 is reduced in response. The low PCO2 must be the compensatory response. Since the primary change involves HCO3-, this is a metabolic process, i.e. Metabolic Acidosis. 4. The anion gap is Na - (Cl + HCO3-) = 132 -(93 + 11) = 28     Since gap is greater than 16, it is therefore abnormal. 5. Calculate the estimated PCO2.   Using Winter's formula; PCO2 = 1.5 × [HCO3-]) + 8 ± 2 = 1.5 ×11 + 8 ± 2 = 22.5 - 26.5. Since the actual PCO2 falls within the estimated range, we can deduce that the compensation is adequate and there is no separate respiratory disorder present. 6. Since anion gap elevated, Assessment: Compensated elevated anion gap acidosis most likely secondary to DKA. Note the absence of ketoses in the urine. This is sometimes seen in early DKA due to the predominance of beta-hydroxybutyrate. The dipstick test for ketoses detect acetoacetate but not beta-hydroxybutyrate.

Case 2 : 

Case 2 Case A 70 year old man with history of CHF presents with increased shortness of  breath and leg swelling.ABG: pH 7.24, PCO2 60 mmHg, PO2  52 HCO3- 27meq 1 Based on the clinical scenario, likely acid base disorders in this patient are: Acute respiratory acidosis secondary to acute pulmonary edema 2 hereThe pH is low, (less than 7.35) therefore by definition, patient is acidemic.

Case 2 : 

Case 2 3. What is the process?  .     PCO2 and HCO3- are abnormal in the same direction, therefore less likely a mixed acid base disorder but not yet ruled out. HCO3- is on the high side of normal and is not consistent with the pH. PCO2 is high and represents acidosis and is consistent with the pH. Therefore it must be the initial change. The high normal HCO3- must be the compensatory response. Since the primary change involves PCO2, this is a respiratory process, i.e. Respiratory Acidosis.. Assessment: Acute respiratory acidosis likely secondary to pulmonary edema.

Case 3 : 

Case 3 A 60 year old homeless man presents with nausea, vomiting and poor oral intake 2 days prior to admission. The patient reports a 3 day history of binge drinking prior to symptoms.  Labs : Serum chemistry: Na 132, K 5.0, Cl 104 , HCO3- 16 , BUN 25 , Cr 1.3, Glu  75 ABG: pH 7.30 , PCO2 29, HCO3- 16 , PO2 92          Serum albumin 1.0                      The patient is acidemic with a low bicarb and low PCO2, suggesting metabolic acidosis. The patient is hyponatremic with a history of nausea, vomiting and poor intake. In this scenario, the metabolic acidosis may either be due to normal anion gap acidosis secondary to vomiting and/or lactic acidosis ketoacidosis secondary to extreme volume loss and poor intake. To rule out lactic acidosis and ketoacidosis, we need to calculate the anion gap. Anion gap = (Na-(Cl +HCO3-) = 132 -(104 +16) = 12

Case 3 : 

Case 3 Assessment: This patient has an elevated anion gap metabolic acidosis which may be due to lactic acidosis or ketoacidosis.

Case - 4 : 

Case - 4 Farrah, a beautiful person, is concerned about her body image so she diets most of the time. Her food intake is erratic and consists mainly of vegetables and fruits; she consumes little meat or table salt. She jogs 60 Km per week and is asymptomatic. When she volunteered for a clinical research project, she was surprised to find that she was hypokalemic. She denied vomiting and the use of diuretics or laxatives. Her ECF is contracted

Discussion of case - 4 : 

Discussion of case - 4 ECF volume contraction, metabolic alkalosis with hypokalemia and high aldosterone level ECF volume contraction with 0 Cl in urine but high Na Positive urine net charge indicative of an anion other than Cl is present Low pH and high osmolal gap indicates that the anion is not HCO3 (bicarbonate is 0) Negative NaCl balance because of poor dietary intake and nonrenal loss, she has an unusual organic anion load from her diet

Case - 5 : 

Case - 5 Solly has episodes of abdominal pain and profuse diarrhea for months. More recently he has vomited on occasion and has suffered from episodic tingling and weakness. He took antacids to relieve his abdominal pain, but their beneficial effect was transitory. Each time his condition reverts to normal without therapy

Discussion of Case - 5 : 

Discussion of Case - 5 Metabolic alkalosis with hypokalemia Bicarbonate gain of non-renal cause secondary to gastric HCl secretion Most-likely HCl loss from GI Low rate of excretion of HCO3 due to decreased GFR ECF volume is not contracted due to Low GFR HCl reabsorption led to improvement in metabolic alkalosis Zollinger-Ellison syndrome

Expected Responses to Primary Acid-Base Disorders: : 

Expected Responses to Primary Acid-Base Disorders:

Case - 6 : 

Case - 6 56 year old man with CVA who is intubated for protection of airway. Placed on Assist Control mode with TV 700 & rate 16. Initial blood gas: pH = 7.56, paCO2 = 20, paO2 = 125 What is the first thing the intern on call needs to ask?

Answer - 6 : 

Answer - 6 Intern requests the patient’s actual respiratory rate. Respiratory rate = 16 Therefore, patient is not overbreathing the ventilator’s set rate and has a 1’ Respiratory alkalosis.

Answer - 6 : 

Answer - 6 Turn the respiratory rate down to 8. (Actual paCO2 x Current resp rate) = (Desired paCO2 x New resp rate) (20 x 16) = (40 x New resp rate) (20 x 16) / 40 = 8 = New resp rate

Thanks for patience : 

Thanks for patience Dr.V.Amuthavalli amuthamd@rediffmail.com