Background: During septic shock management, the evaluation of microvascular perfusion by skin analysis is of interest. We aimed to study the skin capillary refill time (CRT) in a selected septic shock population.
Methods: We conducted a prospective observational study in a tertiary teaching hospital. After a preliminary study to calculate CRT reproducibility, all consecutive patients with septic shock during a 10-month period were included. After initial resuscitation at 6 h (H6), we recorded hemodynamic parameters and analyzed their predictive value on 14-day mortality. CRT was measured on the index finger tip and on the knee area.
Results: CRT was highly reproducible with an excellent inter-rater concordance calculated at 80% [73-86] for index CRT and 95% [93-98] for knee CRT. A total of 59 patients were included, SOFA score was 10 [7-14], SAPS II was 61 [50-78] and 14-day mortality rate was 36%. CRT measured at both sites was significantly higher in non-survivors compared to survivors (respectively 5.6 ± 3.5 vs 2.3 ± 1.8 s, P < 0.0001 for index CRT and 7.6 ± 4.6 vs 2.9 ± 1.7 s, P < 0.0001 for knee CRT). The CRT at H6 was strongly predictive of 14-day mortality as the area under the curve was 84% [75-94] for the index measurement and was 90% [83-98] for the knee area. A threshold of index CRT at 2.4 s predicted 14-day outcome with a sensitivity of 82% (95% CI [60-95]) and a specificity of 73% (95% CI [56-86]). A threshold of knee CRT at 4.9 s predicted 14-day outcome with a sensitivity of 82% (95% CI [60-95]) and a specificity of 84% (95% CI [68-94]). CRT was significantly related to tissue perfusion parameters such as arterial lactate level and SOFA score. Finally, CRT changes during shock resuscitation were significantly associated with prognosis.
Conclusion: CRT is a clinical reproducible parameter when measured on the index finger tip or the knee area. After initial resuscitation of septic shock, CRT is a strong predictive factor of 14-day mortality.