Bl Gas Analyzer

[email protected]

Blood gas analysis is for determine : • That the patient is well oxygenated • Acid-base status of the patient = respiratory acidosis/alkalosis = metabolic acidosis/alkalosis

Blood gas parameters : Arterial • pH • pO2 • pCO2

Venous

7.35-7.45 80-110 35-45

35-40 41-51

pH = the only way to tell if the body is acid or alkaline Normal pH (7.35- 7.45) Acidosis =an acid condition of the blood (acidemia, pH < 7.35) Alkalosis =an alkaline condition of the blood (alkalemia, pH > 7.45)

pO2 = partial pressue of oxygen in blood - Arterial blood (80-100 mmHg) = Lung oxygenation - Venous blood (35-40 mmHg) = Tissue transfer or being oxygenated

pCO2 = pressure (tension) of dissolved CO2 in blood

- gaseous, acid - controlled by lung

Normal ventilation = 35-45 mmHg pCO2 -Hypoventilation -Respiratory acidosis pCO2 -Hyperventilation -Respiratory alkalosis

HCO 3

base excess (BE) - non-respiratory parameter

- solution, basic - regulated mainly by kidney Metabolic

- HCO-3

acidosis alkalosis - HCO3

At pH 7.4 [HCO3/CO2] = 20:1

Henderson-Hesselbalch equation : pH = pKa + log

[A-]

[HA]

At pH 7.4 7.4 = 6.1 + log

[HCO3-]

[H2CO3] [HCO 3 ] 1.3 = log [H2CO3] 20 = [HCO3-] 1 [H2CO3]

Blood collection Arterial > Venous - site - anticoagulation - container - transportation / storage

BGA, BGE, BGA plus E Oxymeter(Co-oxymeter) measure the % of HbO2 & total Hb Tonometer mix the gas with sample or standard Other ISEs measure various parameters as needed

etc.

pH Metab. Acidosis Alkalosis

D I

Res. Acidosis Alkalosis

D I

pCO2 [HCO3-] D I I D

D I I D

Modified SiggaardAnderson Acid-Base Nomogram

Product information: TCM4

Neonatology

Sleep medicine

Wound care

Electrolytes Blood gas analysis Glucose, Urea Amylase Cardiac markers : CK, Troponin

etc.

แพทย์ทำำ gastric suction ทำำให้ผ้ป่วย เกิด Metabolic alkalosis หลังจำกนัน ้ แพทย์ได้ให้ HCl infusion ผล Lab ก่อน และหลังให้ HClSet เป็1นดังSet นี้ 2 Plasma Na K Cl TCO2 Urea Creatinine Anion gap (AG) Blood pH H+ pCO2 HCO3

151 2.8 92 52 7.5 0.14 10

7.54 28 59 53

152 mmol/L 6.0 mmol/L 134 mmol/L 12 mmol/L 12.9 mmol/L 0.18 mmol/L 12 mEq/L 7.18 66 mmol/L 33 mmHg 12 mmHg

ผ้้ป่วยชำย อำยุ 64 ปี มีประวัติกินยำ แก้ปวดเป็นประจำำ เป็ นเวลำนำน Plasma:

Blood :

Na 141 K 5.7 Cl 115 TCO2 17 Urea 21 Creatinine 0.2 Anion gap (AG) 15

pH 7.29 H+ 51 pCO2 36 pO2 98 HCO3 17 Urine pH 4.5 Creatinine clearance 26 ml/min

mmol/L mmol/L mmol/L mmol/L mmol/L mmol/L mEq/L mmol/L mmHg mmHg mmHg

(90-130)

Light-hearted clinical chemistry It was past 5 p.m. in the afternoon of Christmas Eve. I was on the PubMed making a last-minute attempt to unde rstand a clinical syndrome. The Duty Biochemist informed me that an innovative doctor in the Neonatal ICU had be en injecting faeces into the blood gas analyser on the war d, potentially putting the analyser out of use for the enti re holiday period and certainly adding and extra US$100 0 or so to our already strained departmental budget for the replacement of the 28-day cartridge. We thought that the instrument was foolproof….

Recollected by Chris Lam, Hong Kong