Correlation of Arterial and Venous Blood Gases in Patients Presenting with Acute Exacerbation of Chronic Obstructive Pulmonary Disease at Abbottabad

Abstract

  Background: Knowledge of arterial blood gases is necessary for the management of respiratory failure in patients with acute exacerbation of chronic obstructive pulmonary disease (COPD). Due to patient comfort issues, venous blood gas analysis may be considered as a less invasive potential alternative. Objective: The objective of our study was to determine the correlation between arterial and venous pH, PCO2 and HCO3 in patients presenting with acute exacerbation of COPD.     Methodology: This comparative cross-sectional study was carried out in the Department of Pulmonology, Ayub Teaching Hospital Abbottabad. Patients aged 18 to 80 years presenting to the Pulmonology Department from March 2022 to September 2022 with COPD exacerbation were included. Patients in shock, arrhythmia, diabetic ketoacidosis, renal failure and hepatic disease were excluded. Paired arterial and venous blood samples were obtained and analyzed on the spot via a blood gas analyzer. Data was entered into SPSS version 24.0 for analysis Correlation between arterial and venous PH, PCO and HCO were calculated via Pearson correlation. The correlation between arterial and venous PH, PCO and HCO was calculated via Pearson correlation.   Results: The mean age of the patients was 46.72±15.23 years ranging from 20 years to 75 years. The mean weight was 55.40±9.15 kg ranging from 38 kg to 70 kg. In arterial blood mean pH was 7.38±0.04 ranging from 7.31 to 7.46, PCO2 was 40.43±3.38 mmHg ranging from 35 mmHg to 45 mmHg, mean PO2 was 94.00±5.14 mmHg ranging from 85 mmHg to 100 mmHg, mean HCO3 was 24.97±2.02 mmol/L ranging from 22 mmol/L to 28 mmol/L. In venous blood mean pH was 7.35±0.04 ranging from 7.31 to 7.41, PCO2 was 46.17±3.77 mmHg ranging from 41 mmHg to 51 mmHg, mean PO2 was 35.17±5.04 mmHg ranging from 30 mmHg to 40 mmHg, mean HCO3 was 26.58±2.52 mmol/L ranging from 24 mmol/L to 29 mmol/L. There was a strong correlation between arterial and venous pH (r =0.71), PCO2 (r=0.53), PO2 (r=0.27) and HCO3 (r=0.27).    Conclusion: ABGs and VBGs are strongly correlated mutually in patients presenting with acute exacerbation of COPD. VBGs instead of ABGs can be used as a screening test for the detection of hypercapnia in hemodynamically stable patients presenting with acute exacerbation of COPD, and VBG indices can guide the severity of acid-base disturbance.