<prompt> Interpret the following ABG values PaCO-40, HCO-55 mEqL and pH-7.7:Uncompensated metabolic alkalosisMixed respiratory and metabolic acidosisCombined respiratory and metabolic acidosisCompensated respiratory acidosis  <response>: Ans: a Uncompensated metabolic alkalosisRef: Harrisons 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?pH7.35 is an acidosis; pH7.45 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 partialDisorderPrimary ChangeCompensatory ResponseMetabolicAcidosispCO1.2mmHg for every 1mEqLOR pCOlast two digits of pHMetabolicalkalosispCO0.7mmHg for every 1mEqLRespiratoryAcidosispCO Acute will 0.1mmolL per mmHg in PaCOChronic will 0.4mmolLper mmHg in PaCORespiratoryalkalosispCO Acute will 0.2mmolL per mmHg in PaCOChronic will 0.4mmolL per mmHg in PaCO Normal levels of blood pH,pCO and HCOBlood levels criteriaVenousArterialpH7.35-7.407.38-7.45PCO45-50torr35-45torrHCO24-25mEqL23-27mEqLNormal ABG valuesH35-45nmolL35alkalemia,45academiapH7.35-7.457.35acidemia,7.45alkalemiaPO10.6kPaor80mmHg in arterial blood on room airPCO4.7-6.0kPaor35-45mmHg in arterial bloodSpO96 on room airHCO 22-28mmolLBE -2 to 2Lactate 0.4-1.5mmolLStepwise approach for acid-base disorderspH7.35acidosis; pH7.45alkalosisPrimary 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 acidosisPCO1.5x8-2PCO does not fall below 10 mm HgMetabolic alkalosisPCO increases by 7 mm Hg for each 10 mEqL 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 30mEqLChronic respiratory acidosis increases by 3.5 for each 10 mm Hg increase in PCOHCO does not rise above 45mEqLAcute respiratory alkalosis falls by 2 for each 10 mm Hg decrease in PCOHCO does not fall below 18mEqLChronic respiratory alkalosis falls by 4 for each 10 mm Hg decrease in PCOHCO does not fall below 12mEqL 