Mottling in Septic Shock: Ethnicity and Skin Color Matter

Abstract

Background: Skin mottling as a clinical perfusion marker in septic shock is significantly associated with severity and outcome in white-skinned population and its validity as a clinical sign in dark-skinned population is not known. The objectives of this study were to evaluate mottling in septic shock in the Indian ethnic population who has different skin color as compared to the white-skinned population and to assess mottling as an outcome predictor with capillary refill time (CRT) and other biochemical parameters which are the established clinical markers of perfusion in septic shock.

Materials and methods: We conducted a prospective observational study of patients with skin color categories 21-34 on the von Luschan scale or Fitzprick type IV-VI who had septic shock needing a high dose of norepinephrine ≥0.2 μg/kg/min after fluid optimization. The study was conducted in a mixed medical-surgical ICU over 12 months. Two blinded experts (a Dermatologist and a plastic surgeon) independently classified the skin type, validated the occurrence of mottling, and scored mottling in our patients. We recorded the demographics, hemodynamic variables, and mottling score and observed the incidence of mottling and its correlation with predictors of the severity of septic shock. We also compared CRT, arterial lactate, central venous oxygen saturation, and venoarterial PCO₂ gap with occurrence of mottling in septic shock patients.

Results: We included 108 patients with age 61 ± 16 years. Mean Sequential Organ Failure Assessment (SOFA) and Acute Physiology and Chronic Health Evaluation (APACHE) II scores at enrolment were 10.3-21.9, respectively. Incidence of mottling was 20.3% (22/108). CRT >3 seconds was observed in 50.9% (55/108). Development of mottling was significantly associated with 90-day mortality; 20/22 (90.9%) patients died in the mottling group versus 58/86 (65.1%) in the non-mottling group (p = 0.028). Capillary refill time >3 seconds did not corelate with mortality; 40/55 (72.7%) Patients with CRT >3 seconds died versus 32/53 (60.4%) patients died in CRT ≤3 seconds group. Occurrence of mottling could predict mortality; positive predictive value of 90.9% which was comparable to positive predictive value of lactate levels >4 mmol/L, i.e., 94.1%.

Conclusion: The incidence of mottling in septic shock is much less in patients of Indian ethnicity with brown skin color than in white-skinned population. Occurrence of mottling and not delayed CRT, is a better predictor of outcome in this setting.

How to cite this article: Jog SA, Narasimhan VL, Rajhans PA, Akole PV, Pawar B, Bhurke B, et al. Mottling in Septic Shock: Ethnicity and Skin Color Matter. Indian J Crit Care Med 2023;27(12):902-909.

Keywords: Capillary refill time; Non-white skin colored patient population; Outcome; Septic shock; Skin mottling.

Figs 1A to H

Composite figure showing different stages of mottling with mottling score. (A) Normal skin area without mottling–Fitzpatrick scale IV; (B) Grade 1 mottling; (C) Grade 2 mottling; (D) Grade 3 mottling; (E) Grade 4 mottling; (F) Grade 5 mottling extending up to upper limbs; (G) A close-up view of mottled skin; (H) Mottling score: GRADE 0 – Indicates no mottling; GRADE 1 – A small mottling area (coin size) localized to the center of the knee; GRADE 2 – A mottling area that does not exceed the superior edge of the knee cap; GRADE 3 – A mottling area that does not exceed the middle thigh; GRADE 4 – A mottling area that does not go beyond the fold of the groin; GRADE 5 – An extremely severe mottling area that goes beyond the fold of the groin

Flowchart 1

Patient enrollment flowchart

Figs 2A to E

Bar graphs depicting comparison of mottling, lactate levels, CRT, ScVO₂ and V-A PCO₂ gap with 90-day mortality CRT, capillary Refill Time; ScVO₂, central venous oxygen saturation; V-A PCO₂ gap, venoarterial PCO₂ gap