Arterial blood gas (ABG) analysis is among the most important diagnostic tests used in the treatment of critically ill patients, more than those with respiratory failure. It provides rapid and accurate assessment of oxygenation, ventilation, and acid-base balance, which are crucial in making therapeutic decisions in intensive care units [1,2].The presence of abnormalities in the ABG parameters pH, partial pressure of oxygen (PaO2), partial pressure of carbon dioxide (PaCO2) and levels of bicarbonate reflects the severity of respiratory and metabolic dysfunction and are commonly used in clinical practice to monitor disease progression and response to treatment [3,4].

Respiratory failure is one of the leading causes of ICU admission and is associated with high morbidity and mortality worldwide [5,6]. Early identification of patients at high risk of clinical deterioration is essential in the enhancement of clinical outcomes. A number of studies have reported the prognostic value of ABG parameters in critically ill patients, which show that the presence of abnormalities in the form of hypoxemia, hypercapnia, and acidosis is closely related to higher mortality and the need to use mechanical ventilation [7-9].In particular, metabolic acidosis and respiratory acidosis have been shown to reflect severe physiological derangements and poor prognosis [10].Besides the conventional parameters of ABG, serum lactate has become a significant biomarker in the critical care unit.

High lactate levels are evidence of tissue hypoxia and impaired perfusion and have consistently been linked to a higher mortality rate in patients under the ICU [11,12].Current research has reinforced the relevance of integrating the ABG parameters with lactate levels to increase the prognostic power and inform early interventions [13,14].The combined approach helps the clinicians to be more efficient in determining the severity of illness and in the optimal management approaches. Despite the widespread use of ABG analysis, there is still little information on its overall use in predicting clinical outcomes in the critically ill respiratory patients, especially in settings with resource limitations.

Knowledge about the prognostic value of ABG data can help to personally identify the risk of early disease and act accordingly, as well as provide better patient care results. Thus, the present study will focus on assessing how the arterial blood gas parameters can predict the clinical outcomes among the critically ill patients exhibiting the respiratory failure.

This analytical cross-sectional study was conducted in the intensive care units of Doctors Hospital and Farooq Hospital, Lahore over a six-month period. Consecutive sampling technique was used to enroll 170 patients diagnosed with respiratory failure. Patients aged ≥18 years diagnosed with respiratory failure were included in the study. The patients with incomplete records or patients who were discharged against medical advice were excluded. ABG parameters such as pH, PaO2, PaCO2, bicarbonate (HCO3 -), and lactate levels were taken at admission. Clinical outcomes such as ICU mortality, mechanical ventilation requirements and length of stay in the ICU were recorded. Data was analyzed using SPSS version 27. Continuous variables were represented as mean ± SD and categorical variables were represented as frequencies and percentages. Logistic regression and independent t-test were used. The p-value that was deemed to be statistically significant was below 0.05.

There were 170 patients. The average age was 59.8 ± 12.7 years old and males constituted 60% of the study population.

The ICU mortality rate was 37.6% (64 patients). Patients with abnormal ABG parameters demonstrated significantly poorer clinical outcomes.

Table 1: Baseline Characteristics

Table 2: ABG Parameters and Outcomes

Table 3: Predictors of Mortality

The results of the current research indicate that arterial blood gas markers are important predictors of clinical outcomes in patients with respiratory failure and who are critically ill. The association between severe acidosis and increased mortality observed in the present study is consistent with previous literature, and the association between acid-base imbalance and high mortality rates in patients has been recognized in the literature [7,10].Reduction of pH is an indicator of respiratory and metabolic dysfunction and is frequently related to multi-organ failure, thus contributing to the increase of mortality rates [15,16].In this research, high levels of lactate were found among the strongest predictors of death. This observation is consistent with several recent publications that have identified lactate as a valid biomarker of tissue hypoxia and systemic abnormalities in the perfusion of tissues [11,12].Elevated lactate levels indicate anaerobic metabolism and impaired tissue perfusion and have been linked to higher mortality in the ICU in a variety of critical conditions including sepsis and respiratory failure [17,18]. ABG parameters provide a more comprehensive evaluation of patient status, and they can have higher prognostic accuracy when combined with lactate levels. The results of the study also showed that hypoxemia (low PaO2) and hypercapnia (high PaCO2) were significantly correlated with a high need of mechanical ventilation. The recent evidence which confirms that impaired gas exchange is a significant parameter of disease severity in respiratory failure echoes these results [8,19].Patients with severe hypoxemia are more likely to require ventilatory support and early identification of patients in such conditions is mandatory towards preventing further complications [20]. Moreover, the results highlight the necessity to conduct early evaluation and frequent checkups of the ABG parameters in the critically ill patients. Early identification of these abnormalities may facilitate timely intervention, which can go a long way in improving the results. According to recent reports the incorporation of ABG analysis in early warning systems can enhance the quality of clinical decisions and reduce the number of deaths in the ICU [21,22]. In this way, the ABG parameters may be considered as important tools in terms of managing and prognosticating critically ill respiratory patients The present study was conducted in selected hospitals of Lahore, which may limit the generalizability of findings to other healthcare settings and populations. The cross-sectional study design restricts the ability to establish causal relationships between ABG abnormalities and clinical outcomes. In addition, the study relied on single-time admission ABG measurements and did not assess serial changes in ABG parameters during ICU stay. Certain confounding variables including treatment variability, comorbid conditions, and disease severity may also have influenced patient outcomes.

Arterial blood gas parameters, particularly pH and lactate levels, are important predictors of clinical outcomes among critically ill patients with respiratory failure. Early measurement of these parameters may assist in risk stratification and facilitate timely clinical decision-making in intensive care unit (ICU) settings.

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