Comparative Evaluation of Perfusion Index With Lactate and Base Deficit for Assessing Resuscitation Response in...

Introduction  Traumatic shock is a life-threatening condition characterized by inadequate tissue perfusion following severe injury. Early recognition of impaired perfusion and monitoring of the response to resuscitation are essential to prevent organ dysfunction. Although lactate and base deficit are commonly used biochemical markers of tissue hypoperfusion, their measurement requires invasive blood sampling. The perfusion index provides a continuous, non-invasive assessment of peripheral perfusion. This study aimed to compare the perfusion index with lactate and base deficit as indicators of resuscitation response in traumatic shock patients who did not require blood transfusion in the emergency department. Methodology A cross-sectional observational study was conducted from March 2025 to February 2026 involving adult patients with traumatic hemorrhagic shock (Class I-III). A total of 55 patients (n=55) meeting the inclusion and exclusion criteria were recruited through convenience sampling. The perfusion index was measured using a pulse oximeter, and arterial blood gas analysis was performed to assess lactate levels and base deficit at baseline, one hour, and two hours after the initiation of resuscitation. Data were analyzed to evaluate the relationship between the perfusion index and biochemical markers in assessing the response to resuscitation using correlation analysis, kappa statistics, receiver operating characteristic (ROC) curve analysis, and multivariable logistic regression. Results Among 55 patients, the perfusion index (PI) showed a progressive increase during resuscitation, while lactate and base deficit declined significantly. PI increased by +0.67 units per hour, and lactate decreased by -2.28 mmol/L per hour (p<0.001). PI demonstrated moderate negative correlations with lactate (r=-0.42 at baseline to -0.61 at two hours) and base deficit (r=-0.39 to -0.53). Agreement between PI-based and lactate-based response classifications improved over time, with the kappa value increasing from 0.42 at baseline to 0.72 at two hours, and overall agreement rising from 37/55 patients (67.3%) to 46/55 patients (83.6%). Lactate clearance ≥10% per hour was observed in 42/55 patients (76.4%) at one hour and 48/55 patients (87.3%) over 0-2 hours, while a PI increase ≥10% per hour occurred in 46/55 patients (83.6%) at one hour and 48/55 patients (87.3%) over 0-2 hours. ROC analysis demonstrated that PI at two hours had an area under the curve (AUC) of 0.88, with sensitivity 82%, specificity 85%, positive predictive value 80%, and negative predictive value 86%, comparable to lactate clearance (AUC 0.91). A PI value >2.5 at two hours emerged as the strongest independent predictor of an adequate resuscitation response (adjusted odds ratio 3.8, p=0.002). Conclusion The perfusion index demonstrated significant improvement during resuscitation and showed a clear inverse relationship with lactate levels and base deficit, indicating recovery of tissue perfusion. These findings suggest that the perfusion index correlates with established biochemical markers and may serve as an adjunctive bedside parameter during early resuscitation. Overall, the perfusion index may serve as a useful, non-invasive bedside adjunct for monitoring resuscitation response in patients with traumatic shock and may assist clinical decision-making during trauma resuscitation.