Background: Previous research found that serum chloride is an independent predictor of hospital mortality, its increase within 48 hours of admission was linked to a higher percentage of 0.9% saline administration. Furthermore, the number of days that a patient survived was negatively connected with the extent of the serum chloride elevation. So we aimed to predict the outcome among critically ill patients admitted to surgical intensive care unit in Zagazig University Hospitals and its association with serum chloride fluctuations on admission and within 5 days of intensive care unit stay.

Methods: This prospective cohort study was conducted on 300 critically ill patients with age over 18 years old in Surgical Intensive Care Unit (SICU), Faculty of Medicine, Zagazig University hospitals. Chloride level was measured on admission,3rd day and 5th day. According to chloride level on admission the patients was classified to 3 groups: Group 1 included patients with chloride level <95 mEq/L, Group 2 included patients with chloride level 95-105 mEq/L and Group 3 included patients with chloride level > 105 mEq/L.

Results: Longer periods of stay in the intensive care unit were correlated with higher chloride levels at admission (24.33 ± 26.87 days). On ICU admission, patients with hypochloremia had high death rate (19.3%). Positive fluctuation of serum chloride after admission was linked to high mortality rate (11.4%).

Conclusion: Changes in the serum chloride level endanger the clinical outcome of critically ill patients in the form of longer periods of ICU stay and higher rates of mortality.