Evaluation of arterial blood gases of patients with type 1-2 respiratory failure diagnosed in intensive care using the quantitative Stewart method
Authors: AYHAN Feyza , MENTEŞ Oral , YILDIZ Murat , ERASLAN DOĞANAY Güler 
Published: March 2022

Introduction: Arterial blood gases are tests that provide reliable information about the metabolic and respiratory status of patients. In traditional methods, arterial blood gases are evaluated by calculating the bicarbonate concentration and anion gap in the plasma. Since ICU patients almost always have protein and electrolyte disorders, a different method has been suggested instead of the traditional method that neglects electrolyte and protein in the evaluation. In the mathematical model described by Stewart and modified by Figge et al., 4 types of respiratory failure were defined according to their pathophysiology: hypoxemic (type 1), hypercapnic (type 2), perioperative (type 3), and hypoperfusion-induced respiratory failure in shock patients (type 4). The study aims to evaluate the arterial blood gases of intensive care patients with type 1 and type 2 respiratory failure with the Stewart method and compare them with the traditional method.

Material and Method: In the study, serum BUN (blood urea nitrogen), creatinine, glucose, sodium, chlorine, serum BUN (blood urea nitrogen) of 106 patients diagnosed with type 1-2 respiratory failure. Together with potassium, magnesium, albumin values, pH, pCO2, pO2, HCO3, base deficit, and lactate values studied in arterial blood gas sample were determined and evaluated according to the Stewart method.

Results: The length of stay of the patients in the intensive care unit was determined as 17.48±10.58 (minimum 6-maximum 68) days. It was determined that 74 (69.8%) of the patients were discharged and 32 (30.2%) died. When the blood gases and laboratory values of the patients were compared according to the clinical outcomes of the patients, no statistically significant correlation was found between the patients’ mean pH, pCO2, HCO3, base deficit, pO2, albumin, lactate, creatinine, glucose, potassium, and chlorine values and the patients’ discharge or death. BUN values of patients who died were found to be higher than those who were discharged. A statistically significant difference was found between the development of hypoalbuminemia and the length of stay in the intensive care unit. It has been determined that the treatment costs of patients with severe hypoalbuminemia are higher than other patients. The length of stay in the intensive care unit of the patients who did not develop acidosis was found to be statistically significantly lower than the patients who developed metabolic and respiratory acidosis.

Conclusion: While a significant relationship was found between albumin levels, which has an important place in the Stewart method, and the length of stay in the intensive care unit, no relationship was found between albumin levels or lactate levels and mortality. However, increased BUN values were associated with mortality. As the albumin value decreases in patients with hypoalbuminemia, treatment costs increase. There is a need for larger multicenter studies with a larger sample group that will evaluate metabolic status with the Stewart method and investigate its relationship with mortality.