Comparison between PCO2 Gap, Lactate and Procalcitonin as Predictors of Clinical Outcome in ICU Septic Patients
Authors: Kamal Abd Allah Mohammed Mohammed , Mohammad Ahmad Elewa Gamal Eldin , Abd Elghaffar Ahmed Ahmed Othman , Ezzat Ahmed Wagih 
Published: November 2024

Abstract

Background
Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection, if not recognized early and managed promptly, it can lead to septic shock, multiple organ failure and death. Sepsis is associated with high mortality, and the early recognition of the signs of tissue hypo perfusion is crucial in its management.

Aim
The aim of the study was to compare between PCO2 gap, serum lactate and procalcitonin as predictors of clinical outcomes in ICU septic patients regarding 28 days mortality or developing septic shock or multiorgan failure (MOF).

Patients and Method
This prospective observational study was carried out in the ICU of Ain Shams university hospitals and Egypt air hospital. The study was done on 80 cases. Inclusion criteria: Adult septic patients ≥ 21 years old. Exclusion criteria: Patients with history of chronic obstructive pulmonary disease and bronchial asthma or died &lt;48 h of admission. Method: All patients were subjected to complete history taking and Physical examinations to exclude systemic diseases. Investigational Studies: Routine laboratory investigations: complete blood count (CBC), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), liver and kidney functions, PT, PTT and INR. Serum lactate: was done on admission then after 48 hours. PCO2 arterial and central venous (PCo2gap): was done on admission then after 48 hours. Procalcitonin: on admission then after 48 hours. APACHE ΙΙ and SOFA scores were recorded on admission.

Results
patients were classified in to 2 groups according to mortality: survivors group & non survivors group, survivors were n = 60(75%) and non survivors were n = 20(25%). Regarding serum lactate on 1st day of admission and after 48 h, it revealed that survivors group showed significant reduction in serum lactate level at 48 h compared to baseline (p &lt; 0.001). while in non-survivors group there was statistically significant increase in serum lactate after 48 h than at 1st day of admission (P &lt; 0.001), the cutoff point of s. lactate on 1st day was &gt;3.97 mmo/l showed sensitivity of 90% and specificity of 93.33%, while after 48 hours the cutoff point of s.lactate was &gt;2.68mmo/l showed sensitivity of 100% and specificity of 100%. Regarding PCO2 gap on 1st day of admission and after 48 h, it revealed that survivors group showed significant reduction in PCO2 gap after 48 h compared to baseline (p &lt; 0.001). However, non-survivors group showed an increase in PCO2 gap after 48 h compared to baseline with statistical significance (p &lt; 0.001), the cutoff point of PCO2 gap on 1st day was &gt;7.48 mmHg gave sensitivity of 90% and specificity of 90%. While the cutoff point of PCO2 gap after 48 h. was &gt;6.2 mmHg gave sensitivity of 95% and specificity of 95%. Regarding procalcitonin on 1st day of admission and after 48 h, it revealed that survivors group showed significant reduction in procalcitonin after 48 h compared to baseline (p &lt; 0.001). Non-survivors group showed significant increase in procalcitonin after 48 h compared to baseline (p &lt; 0.001), the cutoff point of procalcitonin on 1st day was &gt;2.336 ng/ml gave sensitivity of 90% and specificity of 81.67%. While the cutoff point of procalcitonin after 48h. was &gt;2.14 ng/ml gave sensitivity of 90% and specificity of 85%. Regarding APACHE II severity score on 1st day it revealed that survivors group ranged between 5-17, while in non survivors group ranged between 15-26, revealed that higher APACHE II score associated significantly with increased mortality in non-survivors compared to survivors group (P &lt; 0.0001). Regarding SOFA severity score on 1st day of admission in survivors group ranged between 1-13,while in non survivors group ranged between 10-17. SOFA score was significantly higher in non-survivors compared to survivors group (P &lt; 0.0001). MOF were 25(41.7%) in survivors group and 20(100%) in non-survivors group, there was statistical significant higher frequency of MOF in non-survivors group than survivors group (P &lt; 0.001). Patients who developed septic shock and required vasopressors were 43(71.7%) in survivors group and 20(100%) in non-survivors group, there was statistical significant higher frequency of vasopressors requirement in non-survivors group than survivors group (P = 0.007).

Conclusion
PCO2 gap, serum lactate and procalcitonin in addition to severity scores (APACHE II & SOFA scores) were identified as predictors of clinical outcome in ICU septic patients. Serum lactate followed by PCO2 gap then procalcitonin had comparable prognostic accuracy with severity scores (on admission and after 48 h).