Changing Pattern of Serum Chloride as Prognostic Indicator for Response to Respiratory Support in Cases of Respiratory Failure – An Observational Study

OBJECTIVES: Primary objective was to study the correlation between serum chloride levels at admission and at regular intervals with the mode and degree of respiratory support provided in cases of respiratory failure. Correlation between the serum chloride levels and patient's outcome over next 48 hours in the form of improved, progressed or died was the secondary objective. MATERIALS AND METHODS: After informed consent and approval from Institutional Ethics Committee, patients presenting with respiratory failure (requiring oxygen support for spo2 >92% or partial pressure of oxygen (PaO2) <60 mm Hg or partial pressure of carbon dioxide (PCO(2)) > 50 mm Hg) on room air were enrolled. Patients with chronic kidney disease, chronic liver disease, recent myocardial infarction, stroke, peripheral motor neuropathy, patients intubated prior to arrival in the Emergency Department, diabetic ketoacidosis, traumatic brain injury were excluded. Serum chloride levels were measured at admission and at regular intervals (2 hours, 6 hours, 12 hours, 24 hours, 36 hours and 48 hours) post admission to the hospital. Additional clinical data, including type and degree of respiratory support and outcomes, were documented to assess the relationship between serum chloride dynamics and patient response to treatment. Any patient who got intubated within 2 hours were excluded from the study. Initial choice of respiratory support was on clinician's discretion depending on clinical parameters and arterial blood gas analysis. RESULTS: A total of 139 patients were enrolled, out of which 48 were females. Fifteen patients got intubated within 2 hours of presentation to emergency and were excluded. Mean age of patients enrolled were 46.04 ± 12.34 years [95% CI = 43.86 – 48.22]. Mean chloride levels all patients presenting with respiratory failure were on the lower side 95.29 ± 4.81 mEq/L [95% CI = 93.1-97.47]. Two factor ANOVA showed no significant effect of chloride on the mode of ventilatory support (p= 0.744), but increasing trend of chloride levels at 36 hours (normalisation of initial hypochloremia) was significantly associated with improved outcome (OR 1.35, 95% CI =1.2- 1.52, p<0.001). On Spearman correlational analysis, there was significant small positive correlation between chloride levels at admission and improved outcome of patient [r(124) = 0.27, p = 0.001] and medium negative correlation between chloride levels at 36 hours and improved outcome of patient [r(124) = -0.5, p = 0.01]. CONCLUSION: There was a significant interaction between chloride levels over time and the outcome of patient. It provides insights into the potential temporal influence of chloride levels on patient outcomes, highlighting the need for further investigation in clinical settings to validate these associations. Thus, by identifying high-risk patients based on serum chloride trends, healthcare systems can optimise resource allocation.