Correlation between Arterial and Venous Blood Electrolytes in Acute Exacerbation of Chronic Obstructive Pulmonary Disease: A Cross-sectional Study

Acute Exacerbation of Chronic Obstructive Pulmonary Disease (AECOPD) is a common health problem coupled with huge mortality and morbidity across the world. Acute exacerbation in COPD patients leads to electrolyte disturbances. Routinely, electrolytes are measured from venous blood. Electrolytes can also be measured from whole blood by blood gas analyser along with blood gases measurement. Aim: To study the correlation between venous and arterial blood electrolytes in AECOPD patients. Materials and Methods: The cross-sectional study was conducted at Clinical Biochemistry Laboratory, Government Medical College and Sir Takhtsinhji General Hospital, Bhavnagar, Gujarat, India, from December 2013 to May 2014. Arterial and venous blood were taken at same time from 150 patients of AECOPD and analysed for electrolytes (sodium, potassium and ionised calcium) in arterial blood gas analyser. Correlation of arterial and venous blood electrolyte levels was done by Pearson’s correlation. Results: This study comprised 109 (72.67%) male and 41 (27.33%) female AECOPD patients. Mean age of subjects was 59.01±11.42 years. Mean level of arterial sodium was 143.1±8.81 mmol/L and venous sodium was 144.8±8.47 mmol/L (p-value=0.0973). Mean level of arterial potassium was 3.53±0.73 mmol/L and venous potassium was 3.19±0.56 mmol/L (p-value <0.0001). Mean level of arterial ionised calcium was 0.83±0.13 mmol/L and venous ionised calcium was 0.76±0.17 mmol/L (p-value <0.0001). Correlation coefficient values for sodium, potassium and ionised calcium were 0.878, 0.762 and 0.537, respectively. Conclusion: Arterial sodium and potassium can be used as a substitute of venous sodium and potassium in management of AECOPD patients, while arterial ionised calcium should not be used in place of venous ionised calcium in management of such patients.