Reference Intervals for Venous Blood Gas in Healthy Adults: A One-Year Prospective Study

Background Venous blood gas (VBG) investigation is a widespread option for arterial blood gas analysis because it is easier to draw and has a lower risk of complications during phlebotomy. This study aimed to establish reference intervals for the accurate analysis of VBG results as there is a lack of published data. Method Dr. Ziauddin Hospital hosted the study, which involved 182 healthy adults (96 female participants) between the ages of 20 and 76 years. They comprised 118 medical students (aged 20-32 years) and 64 volunteers (aged 20-76 years), the latter of whom were enrolled following the fulfillment of a health questionnaire. To avoid coagulation, a pre-heparinized syringe was used to draw venous blood from the dorsal or cubital vein (peripheral). The samples were sent directly to the laboratory, where the EasyBloodGasTM analyzer (Medica Corporation, Bedford, MA, USA) completed the analysis of the blood samples in 30 min. Results pH, pO2 (partial pressure of oxygen), pCO2 (partial pressure of carbon dioxide), bicarbonate, and electrolytes i.e. sodium (Na⁺), potassium (K⁺), chloride (Cl^-), and calcium (Ca⁺²) were among the parameters included in non-parametric statistical analysis. The results established VBG reference intervals as follows: pH (7.29-7.43), partial pressure of oxygen (25-70 mmHg), partial pressure of carbon dioxide (35-59 mmHg), bicarbonate (22-30 mmol/L), Na⁺ (134-144 mmol/L), K⁺ (3.1- 4.6mmol/L), Cl^- (101-110 mmol/L) and ionized calcium (1.12-1.30 mmol/L). Conclusion This prospective study determined reference ranges for VBG measurements in healthy persons over one year, addressing the lack of published data from Pakistani institutions. Our research offers significant insights into the standard ranges for pH, pO2, pCO2, bicarbonate, electrolytes, and ionized calcium. The reference intervals established in this study can function as a dependable standard for doctors to appropriately interpret VBG data.