pH disorders and mortality in surgical intensive care unit patients

Abstract

Background:The pH determines the presence of acidemia or alkalemia. If the body has compensated for the disorder, the pH may be in the normal range. Human blood normally has a pH of 7.35-7.45 (H+ = 35-45 nmol/L), so is slightly alkaline. If blood pH is below the range of <7.35, there is acidemia. If it is above the normal range of >7.45, there is an alkalemia. The objective of this study was to investigate association of mortality with the acid-base disorders in surgical ICU patients.

Methods: The study was a prospective, observational study, conducted on the 167 patients admitted in Surgical ICU over a period of eighteen months (January 2014 to June 2015) in Department of Surgery, Mathura Das Mathur Hospital attached to Dr. S. N. Medical College, Jodhpur, Rajasthan, India. pH values were noted at different times. Acidemia and alkalemia were compared in survivors and non survivors.

Results:At admission, acidemia was seen in 26.3% patients and alkalemia in 15% patients. During ICU stay, the prevalence of acidosis and alkalosis increased. In non survivors, before death, acidemia was present in 41.9% and alkalemia in 26.9% patients.

Conclusions:Focusing on pH, in surgical ICU, mortality was shown to be had a U-shaped relationship with pH. Both acidemia and alkalemia are independently associated with high mortality in surgical ICU patients. Mortality is not affected by type (respiratory or metabolic) of acid base disorders. Further studies are needed to find if this association is causal or merely a reflection of differences in severity of illness.