Ans. c (90) (Ref H-17th/l590-91; pg. A-15)In a normal healthy person the arterial oxygen is considered satisfactory if SP02 is more than 90.Arterial O2 tensionPaO212.7 +- 0.7 kPa (95 +- 5 mm Hg)Arterial CO2 tensionPaCO25.3 +- 0.3 kPa (40 +- 2 mm Hg)Arterial O2 saturationSaO20.97 +- 0.02 (97 +- 2%)Arterial blood pHpH7.40 +- 0.02Arterial bicarbonateHCO3-24 + 2 mEq/LBase excessBE0 +- 2 mEq/LDiffusing capacity for carbon monoxide (single breath)DLCO0.42 mL CO/s/mm Hg (25 mL CO/min/mm Hg)Dead space volumeVD2 mL/kg body wtPhysio dead space; dead space-tidal vol ratioVD/VTKnow at rest & exercise(a) Rest < 35% VT(b) Exercise < 20% VTAlveolar-arterial difference for O2P(A -a) O2< 2.7 kPa (20 mm Hg)Educational Point# Alveolar hypoventilation exists by definition when arterial PC02 (PaC02) increases above the normal range of 37-43 mm Hg, but in clinically important hypoventilation syndromes PaC02 is generally in the range of 50-80 mm Hg.# A decrease in the Anion Gap can be due to:- an increase in unmeasured cations;- the addition to the blood of abnormal cations, such as lithium (lithium intoxication) or cationic immunoglobulins (plasma cell dyscrasias);- a reduction in the major plasma anion albumin concentration (nephrotic syndrome); (A fall in serum albumin by 1 g/dL from the normal value decreases the anion gap by 2.5 mEq/L).- a decrease in the effective anionic charge on albumin by acidosis; or- hyperviscosity and severe hyperlipidemia.