IMPACT OF NOREPINEPHRINE DOSAGE INCREASE AND VOLUME EXPANSION ON CAPILLARY REFILL TIME IN SEPTIC SHOCK PATIENTS

Abstract

Background: When evaluating patients with acute circulatory failure, one clinical feature that may be quickly determined at the bedside is the capillary refill time (CRT).Objective: The objective of this observational study was to describe the changes in CRT that occur as a result of volume expansion and increased dosages of norepinephrine, along with related macro-circulatory variables, in patients suffering from septic shock. Study Design: This was an observational study. Setting: The study was conducted at Bahria Town International Hospital Lahore and Services Institute of Medical Sciences. Duration of Study: The study was conducted over six months from January 2, 2023, to July 30, 2023. Methods: We measured mean arterial pressure (MAP), cardiac index (CI), and five consecutive CRT readings in 40 septic shock patients. These measurements were taken before and after a 500 mL saline infusion in 20 patients and before and after an increase in norepinephrine dosage in another 20 patients. Results: The "norepinephrine" group had lower SAPS II and SOFA scores than the "volume expansion" group. When all patients were assessed together, volume expansion significantly lowered heart rate while increasing MAP, diastolic arterial pressure, CI, CVP, and CRT. Fluid-induced increases in CI of  ≥ 15% were observed in 11 patients (55%). In fluid responders, fluid infusion significantly raised MAP by 31% (11-49%) and CI by 26% (20-42%). Increased norepinephrine levels may lower CRT in patients with a baseline value of fewer than 3 seconds. Increasing norepinephrine has a low possibility of decreasing CRT in patients with baseline CRT  ≥  3 seconds if the MAP increase is <15%. However, the decrease in CRT is inconsistent in patients with baseline CRT ≥ 3 seconds when norepinephrine increases MAP by  ≥ 15%. Univariate regression analysis revealed a correlation between the absolute value of CRT and lactate levels, heart rate, norepinephrine dosage, gender, SAPS II, and ICU mortality. In a multivariate analysis that included all physiological parameters with a p-value <0.1 in univariate linear regression, only lactate upon admission had a significant association with the absolute value of CRT. Conclusion: CRT uncommonly improves with therapy in individuals with septic shock and prolonged CRT when volume expansion raises cardiac output by <15% and increasing the dosage of norepinephrine increases MAP by <15%. CRT's response varies when there are significant effects of fluid infusion on cardiac output and norepinephrine on MAP; in some patients, it decreases while remaining consistent in others. CRT functions as an indicator of microcirculation in this context.