Application of standard bicarbonate/carbonic acid ratio in arterial blood gas analysis

Arterial blood gas (ABG) analysis is a challenging but clinically very important diagnostic test in intensive care unit patients but combined acid base disorders either due to compensatory mechanisms or mixed disorders are often difficult and sometimes confusing. The aim of the current research study is to find out the clinical significance of two newer ratios derived using standard bicarbonate, bicarbonate and carbonic acid values. The study included 176 arterial blood gas samples collected from I.C.U patients and ABG analysis were done which classified them into various acid base disorder groups. Bicarbonate/carbonic acid ratio and standard bicarbonate/carbonic acid ratio values were calculated for all the samples. These two values were divided to form a newer ratio 1 (HCO3 /H2CO3)/(Std HCO3 /H2CO3) and the difference between the two values form an another newer ratio 2 (HCO3 - Std HCO3)/H2CO3. The relation between pH, pCO2and the two newer ratios were graphically analysed. Mean ± standard deviation was calculated for both the ratios 1 and 2 in various acid-base disorder groups. One way ANOVA statistical test was applied and the two ratios are found to be statistically significant at p<0>2 values. The study concluded that the two newer ratios derived may provide some clues regarding the disturbances affecting the acid-base homeostasis which may be used as a discriminator between various acid-base disorders.