ABG tests are frequent laboratory tests that are the gold standard for assessing respiratory failure and acid-base balance problems. (2), The arterial oxygen pressure (PaO2) value offers us information about the oxygenation state, while the arterial carbon dioxide pressure (PaCO2) value gives us information about the ventilation state (acute or chronic) and the acid-base condition. When analyzing arterial gases, the first thing that is noticed is the pH, which remains in the range of (7.37–7.42). A slight change in pH leads to a change in the concentration of hydrogen ions. Patients with covid-19 had lower PO2, and SO2 levels, and higher urea and creatinine levels in the current study which indicates the well-documented impact of Covid-19 on respiratory and renal systems(17).
Pneumonia is the most common symptom of COVID-19 and is almost always identified in hospitalized patients. It often presents as bilateral ground-glass opacities with or without consolidations(18). Extensive pneumonia is a potentially fatal infectious illness because it interferes with respiratory gas exchange and causes a shift in minute ventilation. As a result, acid-base abnormalities of respiratory origin were predicted complications in our COVID-19 group.
After respiratory alkalosis, metabolic alkalosis (20.7%) was the second most common alteration in the current study. The cause of this condition was difficult to detect in our patient population. The most likely theory would be dehydration caused by fever, dyspnea, and lack of appetite.
Despite the fact that no statistically significant variations in pulmonary gas exchange and diuretic were found when compared to patients with normal pH(19).
The average age of the subjects in our research was 61.58 years, and 54.5% of them were men. The first study on COVID-19 patients found 41 cases with a median age of 49 years and 73% males in the study group. In another study describing the clinical symptoms of COVID-19 in 710 patients, 52 patients were found to be severely sick. The severely sick patients had an average age of 59.7 years, were 67% male, and 40% had a comorbid illness. In this population, the fatality rate was 61.5% (20).
Two other studies compare admission ABG results with the degree of pulmonary inflammation as assessed by computer tomography and the prognosis of 79 emergency room patients with SARS-CoV-2 infection. These findings are consistent with the findings of the current study. They concluded that admission ABG results might indicate the degree of pulmonary involvement and a worse prognosis in COVID-19 patients (12). They also discovered higher pH values, which are consistent with our findings, but they did not compare these to the results. The pH and HCO3 values on the admission ABG analysis were higher in the survivor subgroup of our study compared to nonsurvivors. These results also agreed with the findings of the Wuhan No. 1 Hospital study (13).
Another finding of the current study is that the Hco3 level in non-survivor patients is significantly lower than in survivor. Patients with metabolic acidosis and low bicarbonate concentration should be assessed individually because they are connected to high mortality in severe COVID-19 patients and are caused by multiple organ failure(21).
An increased pH was found in 29.4% of patients in another study25 evaluating admission ABGs in 91 patients, 60 of whom were still admitted at the time of write-up. This study, however, concentrated on epidemiological and clinical characteristics and did not link ABG findings to patient outcomes(22).
It is unknown why such a high number of COVID-19 ICU patients had alkalemia, which is thought to be unusual in critical care (23). Certainly, alkalemia produced at the kidney level appears to be the most plausible cause, with increased mineralocorticoid activation (endogenous or exogenous) being a potential. COVID-19 is thought to upregulate the conventional RAS pathway and produce metabolic alkalemia.
The RAS is largely responsible for regulating blood pressure, hydration balance, electrolyte concentrations, and the body's acid-base condition. It has two well-defined arms: the conventional vasoconstrictive route and the protective pathway. Alternately, due to its impact on the mineralocorticoid system, corticosteroid medication could be a contributing cause. Dexamethasone has received a lot of attention for its usage in critically sick patients receiving ventilator support, where higher survival rates have been seen. 28 The activation of mineralocorticoids will cause hypertension, alkalemia, and hypokalemia(24).
It is interesting to note that in the current study 83.3% of the patients have high blood sugar levels and worse prognosis. In COVID-19, diabetes is linked to poorer outcomes, including a larger percentage of ICU admissions, ARDS, and mechanical ventilation(25).
The retrospective nature of the study, the small number of patients, and the lack of a control group limit the generalizability of these findings. Larger investigations, free of selection bias, are thus required to establish the distribution of acid-base abnormalities in COVID-19 patients and to confirm the potential link between metabolic acidosis and death risk in this subset of patients.