Comparison Of Arterial and Venous Blood Gas Values Among Critically Ill Patients

Background and objectives: Arterial blood gas analysis evaluates metabolic and ventilation conditions. Nevertheless, the procedure is characterized by intense discomfort and technical intricacy. In contrast, central venous sampling is a safer and more readily available option for patients with a central line. This research evaluates the agreement between central venous and arterial blood gas measurements in critically ill patients. Methods: In this single-center cross-sectional study, data was collected from May to August of 2023 in the intensive care unit of Shar Hospital in Sulaymaniyah City, Iraq. One hundred pairs of arterial and central venous blood gases were obtained from 100 adult patients. All were mechanically ventilated; the mean age was 54, and 60% of patients were male. For each pair of arterial and central venous samples, pH, partial pressure of carbon dioxide standard bicarbonate, extracellular base excess, lactate, and ionized calcium were recorded using a single point-of-care blood gas analyzer. Results: Using the Bland–Altman method, arterial and central venous blood gas values showed high levels of agreement, with mean arteriovenous differences of pH 0.036 ± 0.033, partial pressure of carbon dioxide −4.10 ± 3.581, bicarbonate 0.46 ± 1.542, base excess −0.38 ± 2.625, Lactate −0.172 ± 0.624, and ionized calcium −0.022 ± 0.224. Conclusions: The pH, partial pressure of carbon dioxide, standard bicarbonate, extracellular base excess, lactate, and ionized calcium levels in central venous blood can be used instead of arterial blood gas measures in the intensive care unit.