Interpret the following ABG values PaCO-40, HCO-55 mEq/L and pH-7.7:
Ans: (a) Uncompensated metabolic alkalosisRef: Harrison's Principles of Internal Medicine, 19th edition,Chapter 66 20.Step 1: Review the patientExamine the patient for clues as to the type of disturbance.Step 2: Analyse the oxygenationLook for signs of hypoxia, by assessing the PaO and SaO.Step 3: Assess the pH: Is there an acidosis or alkalosis?pH<7.35 is an acidosis; pH>7.45 is an alkalosisStep 4: Assess for respiratory disturbanceConsider the state of alveolar ventilation by evaluating the PaCO.Step 5: Assess for metabolic disturbanceExamine HCO and BE in relation to pH, to determine metabolic involvement.Step 6: Establish if the disturbance is compensatory or mixedObserve the pH to determine if the compensation is appropriate for the primary disturbance (complete or partial)DisorderPrimary ChangeCompensatory ResponseMetabolicAcidosis||pCO1.2mmHg for every 1mEq/L|OR pCO=last two digits of pHMetabolicalkalosis||pCO0.7mmHg for every 1mEq/L|RespiratoryAcidosis|pCO Acute will |0.1mmol/L per mmHg| in PaCOChronic will |0.4mmol/Lper mmHg| in PaCORespiratoryalkalosis|pCO Acute will |0.2mmol/L per mmHg| in PaCOChronic will |0.4mmol/L per mmHg| in PaCO Normal levels of blood pH,pCO and HCOBlood levels criteriaVenousArterialpH7.35-7.407.38-7.45PCO45-50torr35-45torrHCO24-25mEq/L23-27mEq/LNormal ABG valuesH+(35-45nmol/L)<35=alkalemia,>45=academiapH(7.35-7.45)<7.35=acidemia,>7.45=alkalemiaPO(>10.6kPaor>80mmHg in arterial blood on room air)PCO(4.7-6.0kPaor35-45mmHg in arterial blood)SpO(>96% on room air)HCO (22-28mmol/L)BE (-2 to +2)Lactate (0.4-1.5mmol/L)Stepwise approach for acid-base disorderspH<7.35=acidosis; pH>7.45=alkalosisPrimary change in HCO-metabolicIf the change in HCO is in keeping with the pH (i.e., acidosis + decreased HCO), the problem is metabolicIf the change in HCO is opposite with the pH (i.e., acidosis + increased HCO), the problem is compensatory metabolicPrimary change in CO-respiratoryIf the change in CO is in keeping with the pH (i.e., acidosis + increased CO), the problem is respiratoryIf the change in CO is opposite with the pH (i.e., acidosis + decreased CO), the problem is compensatory respiratoryMixed acid-base disordersPresent when compensation is not appropriateCompensation never overcorrects the primary disturbance Expected compensationLimit of compensationMetabolic acidosisPCO=1.5x+8+-2PCO does not fall below 10 mm HgMetabolic alkalosisPCO increases by 7 mm Hg for each 10 mEq/L increase in serum PCO does not rise above 55mmHgAcute respiratory acidosis increases by 1 for each 10 mm Hg increase in PCOHCO does not rise above 30mEq/LChronic respiratory acidosis increases by 3.5 for each 10 mm Hg increase in PCOHCO does not rise above 45mEq/LAcute respiratory alkalosis falls by 2 for each 10 mm Hg decrease in PCOHCO does not fall below 18mEq/LChronic respiratory alkalosis falls by 4 for each 10 mm Hg decrease in PCOHCO does not fall below 12mEq/L
Uncompensated metabolic alkalosis
Mixed respiratory and metabolic acidosis
Combined respiratory and metabolic acidosis
Compensated respiratory acidosis
Fluid & Electrolyte