| Abstract |
Introduction: The acid-based balance of plasma is part of the homeostasis of the human organism, aiming at the balance between acids and bases which is reflected by plasma pΗ. When pΗ is out of acceptable limits then the physiological functions of the human body are affected. The assessment of the acid-based balance (OBI) of the plasma of severely ill patients is undoubtedly an examination that provides information on understanding the severity and pathophysiology of the disease. Methods of identifying and assessing these metabolic disorders are in principle the traditional approach based on the concentration of plasma bicarbonates (HCO3-), Base Excess (BE) and anion gap estimation (Anion Gap, AG) and secondly on the physicochemical approach, known as the Stewart method. The latter method identifies three independent variables that can determine acid base balance in the human organism, and these are: a. the partial pressure of CO2 (pCO2) b. the Strong Ion Difference (SID), and c. the total of non-volatile acid patients (mainly albumin and inorganic phosphorus). The dependent pH variables and bicarbonate concentration [HCO3-] change simultaneously if one of the independent variables changes. Metabolic acid bace balance disorders are common in severely ill patients and for this reason their understanding and monitoring is a critical point in Intensive Care practice. The traditional OBI assessment method is unable to deepen and accurately explain complex metabolic disorders occurring in severely affected patients. Studies have shown that the Stewart physicochemical approach statistically identifies more patients with metabolic disorders compared to the [HCO3-], BE and AG methods. However, when using the corrected AG value, the diagnostic ability is similar to both methods. Attempts have been made to correlate acid base balance and outcome parameters, while the superiority of one of the two OBI assessment methods over the other is questionable regarding prognostic predictive outcome.
Objectives: The purpose of the study is to calculate and evaluate the acid-based balance of children treated in the ICU of children using HCO3-, BE and AG-based calculation methods, as well as the Stewart physicochemical approach. These methods will be compared with each other in terms of clinical utility, early diagnostic ability, ability to detect metabolic disorders, and their predictive value in relation to the outcome of severely impaired children.
Material and Methods: This is a retrospective study of children hospitalized in pediatric ICUin University Hospital of Heraklion between 2013 and 2017. Patient demographics, diagnosis, co-morbidity, hospitalization time, duration of mechanical ventilation, fluid delivery and outcome were recorded. In addition, pH, pO2, pCO2, HCO3, Base Excess values were recorded, while from biochemical indices the values of Na, K, P, Ca, Mg, Cl, albumin and lactate. They were calculated based on the above anion gap (calculated and corrected), the difference of strong ions (SID) and the strong ion gap. Long-term correlations of the above-mentioned values were studied during the first three days of hospitalization, as well as correlations between methods of finding metabolic disorders, hospitalization time, mechanical ventilation time and the outcome of pediatric patients
Results: 415 severely pediatric patients, 61% boys, median age 5.5 years (1.5-11), median hospitalization 5 days (3-10) were studied. Mechanical ventilation was 51.7%. The causes of induction more related to metabolic disorders were in turn surgical, neurological, respiratory, metabolic and circulatory. Compared to BE and [HCO3-] based methods, the physicochemical approach was statistically significant more patients with metabolic disturbances (p <0.001). The most commonly found metabolic disorder was metabolic acidosis (p <0.001), which was recognized by all methods. Although a good linear correlation between SIDeff and BE (R2 = 0.607) and [HCO3-] (R2 = 0.875) was found, a discrepancy between physicochemical and traditional approaches (p <0.001) was noted. A series of metabolic disorders based on the physicochemical approach with normal acid base balance due to a physiological BE value and / or [HCO3-].P &lllt;0.001), where the initial pathological values showed a tendency to recover, except for the chloride that showed an anode trend (p = 0.002) and phosphorus and albumin that had a decreasing trend over time ( p <0.001). Survival was associated with all three methods, better with physicochemical (p = 0.008). The physicochemical approach was statistically significant in predicting mortality in patients with co-morbidity, and children with chronic disease and metabolic alkalosis (p <0.001) had a worse prognosis.
Conclusions: The most common metabolic disorder of severely ill children is metabolic acidosis, which was found by all three methods. All these methods were related to survival prognosis and better physicochemical. The physicochemical approach recognized more metabolic disturbances ("hidden") than traditional methods. Larger mortality risk was seen in patients with free booster and metabolic acidosis and patients with co-morbidity and metabolic alkalosis.
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Σύγκριση μεθόδων εκτίμησης οξεοβασικής ισορροπίας σε παιδιατρικούς ασθενείς σε Μονάδα Εντατικής Θεραπείας
