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A pilot study of quantitative capillary refill time to identify high blood lactate levels in critically ill patients
  1. Naoto Morimura1,
  2. Kohei Takahashi1,
  3. Tomoki Doi1,
  4. Takahiro Ohnuki2,
  5. Tetsuya Sakamoto2,
  6. Yasuyuki Uchida2,
  7. Hiroki Takahashi2,
  8. Takashi Fujita2,
  9. Hiroto Ikeda2
  1. 1Department of Emergency Medicine, Yokohama City University Graduate School of Medicine, Yokohama, Japan
  2. 2Department of Emergency Medicine, Teikyo University School of Medicine, Tokyo, Japan
  1. Correspondence to Professor Naoto Morimura, Department of Emergency Medicine, Yokohama City University Graduate School of Medicine, 4-57 Urafunecho, Minami-Ku, Yokohama, Kanagawa 232-0034, Japan; molimula{at}, molimula{at}


Introduction We developed a new device to quantify capillary refill time (CRT) by applying the pulse oximeter principle, and evaluated the correlation between quantitative CRT (Q-CRT) and hypoperfusion status, as represented by blood lactate levels, in critically ill patients.

Methods A pilot study was undertaken in the intensive care unit (ICU) in a tertiary emergency medical centre. While the pulse oxygen saturation sensor was placed on the finger of the patients, transmitted light intensity (TLI) was measured with a pulse oximeter (OLV-3100; Nihon Kohden, Tokyo, Japan) before and during compression of the finger. Q-CRT was defined as the interval from the release of compression to the time when TLI reached 90% of baseline.

Results Q-CRT was analysed in a total of 57 waveforms among 23 patients and statistically correlated with lactate levels (Spearman's rank correlation coefficient, 0.681; p<0.001). The cut-off value of Q-CRT for predicting a lactate level of ≥2.0 mmol/L was 6.81 s (area under the curve (AUC) (95% CI 1.000 (1.000 to 1.000), p<0.001), and the value for predicting a lactate level of ≥4.0 mmol/L was 7.27 s (AUC=0.989 (95% CI 0.954 to 1.000), p<0.001).

Conclusions Q-CRT correlated with blood lactate levels in this pilot study. The most useful threshold for Q-CRT was ∼6–8 s. Further study is needed to investigate the potential role of this modality as a non-invasive predictor of hypoperfusion in the emergency department, ICU and operating room settings.

  • Assessment
  • Intensive Care
  • Research, Clinical
  • Clinical Assessment
  • Equipment Evaluation

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