Quantitative capillary refill time predicts sepsis in patients with suspected infection in the emergency department: an observational study

Skin-color-independent robust assessment of capillary refill time

Capillary Refill Time (CRT) assesses peripheral perfusion in resource-limited settings. However, the repeatability and reproducibility of CRT measurements are limited for individuals with darker skin. This paper presents quantitative CRT measurements demonstrating good performance and repeatability across all Fitzpatrick skin phototypes. The study involved 22 volunteers and utilized controlled compression at 7 kPa, an RGB video camera, and cocircular polarized white LED light. CRT was determined by calculating the time constant of an exponential regression applied to the mean pixel intensity of the green (G) channel. An adaptive algorithm identifies the optimal regression region for noise reduction, and flags inappropriate readings. The results indicate that 80% of the CRT readings fell within a 20% range of the expected CRT value. The repetition standard deviation was 17%. These findings suggest the potential for developing reliable and reproducible quantitative CRT methods for robust measurements in patient triage, monitoring, and telehealth applications.

Association of Sublingual Microcirculation Parameters and Capillary Refill Time in the Early Phase of ICU Admission

OBJECTIVES

This observational study was conducted to investigate capillary refill time (CRT) during the early phase of ICU admission in relationship with microvascular flow alteration and outcome in critically ill patients.

DESIGN

Prospective, observational, pilot study.

SETTING

ICU in a university hospital.

PATIENTS

Two hundred eighty-two critically ill adult patients admitted to the ICU.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

All patients underwent simultaneous measurements by CRT and sidestream dark field imaging within 24 hours of ICU admission. Other clinical data such as demographic characteristics, hemodynamics, laboratory values, treatment, and physiologic parameters were also included simultaneously. Microcirculatory measurements were performed at 10.2 ± 5.7 hours after ICU admission. Of the 282 included patients, 106 (37.6%) were female, the median (interquartile range) age was 63 years (53-74 yr), and the median Sequential Organ Failure Assessment (SOFA) score was 5 (2-7). The primary finding was the association between CRT and simultaneous the condition of peripheral circulation (microvascular flow index [MFI]: r = -0.4430, p < 0.001; proportion of perfused vessels: r = -0.3708, p < 0.001; heterogeneity index: r = 0.4378, p < 0.001; perfused vessel density: r = -0.1835, p = 0.0020; except total vessel density: p = 0.9641; and De Backer score: p = 0.5202) in critically ill patients. In addition, this relationship was also maintained in subgroups. Microcirculatory flow abnormalities, 28-day mortality, and SOFA score appeared to be more severe for increasing CRT. In a multivariable analysis, prolonged CRT was independently associated with microvascular flow abnormalities (MFI < 2.6; odds ratio [OR], 1.608; 95% CI, 2.1-10.2; p < 0.001). Similarly, multivariable analysis identified CRT as an independent predictor of 28-day mortality (OR, 1.296; 95% CI, 1.078-1.558; p = 0.006).

CONCLUSIONS

In our ICU population, a single-spot prolonged CRT was independently associated with abnormal microcirculation and increased mortality.

Capillary Refill Time and Serum Lactate as Predictors of Mortality and Postoperative Extracorporeal Membrane Oxygenation Requirement in Congenital Heart Surgery

Multiple tissue perfusion markers are described to guide therapy in critically ill pediatric patients undergoing congenital heart surgery. Given the advantages of capillary refill time, our goal is to determine its predictive capacity for mortality and postoperative extracorporeal oxygenation requirements in congenital heart surgery and compare it to serum lactate. We conducted a prospective cohort observational study in a single high-complexity university hospital. Serum lactate and capillary refill time were measured at five predetermined time points: preoperative, immediate postoperative, 6, 12, and 24 h after the surgery. Prolonged immediate postoperative, 6 h, and 12 h capillary refill time measurements turned out to be independent risk factors for both outcomes. The capillary refill time area under the curve ranged between 0.70 and 0.80, while the serum lactate resulted between 0.79 and 0.92 for both outcomes. Both tissue perfusion markers resulted in mortality and extracorporeal oxygenation requirement predictors. Given the advantages of capillary refill time over serum lactate, a monitoring strategy including these two perfusion markers should be considered for congenital heart surgeries.

Evaluation of electronic measurement of capillary refill for Sepsis screening at ED triage

OBJECTIVE

To evaluate the association between capillary refill time (CRT) measured by a medical device and sepsis among patients presenting to the Emergency Department (ED).

METHODS

This prospective observational study enrolled adult and pediatric patients during ED triage when sepsis was considered a potential diagnosis by the triage nurse. Patients were enrolled at an academic medical center between December 2020 and June 2022. CRT was measured by a research assistant using an investigational medical device. The outcomes included sepsis and septic shock defined using sep-3 criteria, septic shock defined as IV antibiotics and a vasopressor requirement, ICU admission, and hospital mortality. Other measures included patient demographics and vital signs at ED triage. We evaluated univariate associations between CRT and sepsis outcomes.

RESULTS

We enrolled 563 patients in the study, 48 met Sep-3 criteria, 5 met Sep-3 shock criteria, and 11 met prior septic shock criteria (IV antibiotics and vasopressors to maintain mean arterial pressure of 65). Sixteen patients were admitted to the ICU. The mean age was 49.1 years, and 51% of the cohort was female. The device measured CRT was significantly associated with the diagnosis of sepsis by sep-3 criteria (OR 1.23, 95% CI 1.06-1-43), septic shock by sep-3 criteria (OR 1.57, 95% CI 1.02-2.40), and septic shock defined as receipt of IV antibiotics and a vasopressor requirement (OR 1.37, 95% CI 1.03-1.82). Patients with CRT >3.5 s measured by the DCR device had an odds ratio of 4.67 (95%CI 1.31-16.1) of septic shock (prior definition), and an odds ratio of 3.97 (95% CI 1.99-7.92) of ICU admission, supporting the potential for the 3.5-s cutoff of the DCR measurement.

CONCLUSIONS

CRT measured by a medical device at ED triage was associated with the diagnosis of sepsis. Objective CRT measurement using a medical device may be a relatively simple way to improve sepsis diagnosis during ED triage.

Fluids and vasopressors in septic shock: basic knowledge for a first approach in the emergency department

Much research, both pathophysiological and clinical, has been produced about septic shock during the last 20 years. Nevertheless, many aspects of treatment are still controversial, among these the approach to the administration of fluids and vasopressors. After the first clinical trial on Early goal-directed therapy (EGDT) was published, a liberal approach to the use of fluids and conservative use of vasopressors prevailed, but in recent years a more restrictive use of fluids and an earlier introduction of vasopressors seem to be preferred. Although both treatments are based on sound pathophysiological knowledge,  clinical evidence is still inadequate and somehow controversial.  In this non-systematic review, recent research on the hemodynamics of septic shock and its treatment with fluids and inotropes is discussed. As a conclusion, general indications are proposed for a practical approach to patients in septic shock.

Recent Advances in Bedside Device-Based Early Detection of Sepsis

Early detection of sepsis is challenging to achieve with current diagnostic methods, leading to expenditures of $27 billion annually in the United States with significant associated mortality. Various scoring systems have been proposed such as the sequential organ failure assessment (SOFA) and systemic inflammatory response syndrome (SIRS) criteria for identification of sepsis, but their sensitivities range from 60% to 70% when used in the emergency department triage. Other methods for the recognition of sepsis may rely on laboratory work, in addition to vitals monitoring, and are often outpaced by the development of sepsis. Automated alerts have not shown any reduction in mortality thus far. New technology may fill a critical gap in the early detection of sepsis. The ideal bedside screening device for would demonstrate rapid time to result, high portability, and high sensitivity to not miss cases, but also reasonable specificity to prevent provider fatigue from excessive false alerts. Non-invasive end-organ perfusion devices analyzing lactate and capillary refill time (CRT) tend to perform well in speed and portability, but may be less sensitive. Biomarker devices demonstrate a wider array of performance metrics. Those analyzing a single biomarker tend to be more sensitive but are less specific to the diagnosis of sepsis than technologies that assess multiple biomarkers, which in turn have lower sensitivity. Additionally, biomarker devices are generally invasive requiring blood samples, which may or may not be feasible in all patients especially when serial draws are needed. Sepsis is a complex disease process and most likely will require a combination of improved technology in addition to vital signs and high-risk patient history for better recognition. This review examines recent advances in the device-based early detection of sepsis between 2017 and 2020 with emphasis on bedside diagnostics, divided into markers of perfusion and biomarkers commonly implicated in sepsis.

Point-Of-Care Capillary Refill Technology Improves Accuracy of Peripheral Perfusion Assessment

Background: Peripheral perfusion assessment is used routinely at the bedside by measuring the capillary refill time (CRT). Recent clinical trials have shown evidence to its ability to recognize conditions with decreased end organ perfusion as well as guiding therapeutic interventions in sepsis. However, the current standard of physician assessment at the bedside has shown large variability. New technology can improve the precision and repeatability of CRT affecting translation of previous high impact research.

Methods: This was a prospective, observational study in the intensive care unit and emergency department at a quaternary care hospital using a non-invasive finger sensor for CRT. The device CRT was compared to the gold standard of trained research personnel assessment of CRT as well as to providers clinically caring for the patient.

Results: Pearson correlations coefficients were performed across 89 pairs of measurements. The Pearson correlation for the device CRT compared to research personnel CRT was 0.693. The Pearson correlation for the provider CRT compared to research personnel CRT was 0.359.

Conclusions: New point-of-care technology shows great promise in the ability to improve peripheral perfusion assessment performed at the bedside in the emergency department triage and during active resuscitation. This standardized approach allows for better translation of prior research that is limited by the subjectivity of manual visual assessment of CRT.

Cutting-Edge Technology for Rapid Bedside Assessment of Capillary Refill Time for Early Diagnosis and Resuscitation of Sepsis

Sepsis currently affects over 30 million people globally with a mortality rate of ~30%. Prompt Emergency Department diagnosis and initiation of resuscitation improves outcomes; data has found an 8% increase in mortality for every hour delay in diagnosis. Once sepsis is recognized, the current Surviving Sepsis Guidelines for adult patients mandate the initiation of antibiotics within 3 h of emergency department triage as well as 30 milliliters per kilogram of intravenous fluids. While these are important parameters to follow, many emergency departments fail to meet these goals for a variety of reasons including turnaround on blood tests such as the serum lactate that may be delayed or require expensive laboratory equipment. However, patients routinely have vital signs assessed and measured in triage within 30 min of presentation. This creates a unique opportunity for implementation point for cutting-edge technology to significantly reduce the time to diagnosis of potentially septic patients allowing for earlier initiation of treatment. In addition to the practical and clinical difficulties with early diagnosis of sepsis, recent clinical trials have shown higher morbidity and mortality when septic patients are over-resuscitated. Technology allowing more real time monitoring of a patient's physiologic responses to resuscitation may allow for more individualized care in emergency department and critical care settings. One such measure at the bedside is capillary refill. This has shown favor in the ability to differentiate subsets of patients who may or may not need resuscitation and interpreting blood values more accurately (1, 2). This is a well-recognized measure of distal perfusion that has been correlated to sepsis outcomes. This physical exam finding is performed routinely, however, there is significant variability in the measurement based on who is performing it. Therefore, technology allowing rapid, objective, non-invasive measurement of capillary refill could improve sepsis recognition compared to algorithms that require lab tests included lactate or white blood count. This manuscript will discuss the broad application of capillary refill to resuscitation care and sepsis in particular for adult patients but much can be applied to pediatrics as well. The authors will then introduce a new technology that has been developed through a problem-based innovation approach to allow clinicians rapid assessment of end-organ perfusion at the bedside or emergency department triage and be incorporated into the electronic medical record. Future applications for identifying patient decompensation in the prehospital and home environment will also be discussed. This new technology has 3 significant advantages: [1] the use of reflected light technology for capillary refill assessment to provide deeper tissue penetration with less signal-to-noise ratio than transmitted infrared light, [2] the ability to significantly improve clinical outcomes without large changes to clinical workflow or provider practice, and [3] it can be used by individuals with minimal training and even in low resource settings to increase the utility of this technology. It should be noted that this perspective focuses on the utility of capillary refill for sepsis care, but it could be considered the next standard of care vital sign for assessment of end-organ perfusion. The ultimate goal for this sensor is to integrate it into existing monitors within the healthcare system.

Advances in the Approaches Using Peripheral Perfusion for Monitoring Hemodynamic Status

Measures of peripheral perfusion can be used to assess the hemodynamic status of critically ill patients. By monitoring peripheral perfusion status, clinicians can promptly initiate life-saving therapy and reduce the likelihood of shock-associated death. Historically, abnormal perfusion has been indicated by the observation of pale, cold, and clammy skin with increased capillary refill time. The utility of these assessments has been debated given that clinicians may vary in their clinical interpretation of body temperature and refill time. Considering these constraints, current sepsis bundles suggest the need to revise resuscitation guidelines. New technologies have been developed to calculate capillary refill time in the hopes of identifying a new gold standard for clinical care. These devices measure either light reflected at the surface of the fingertip (reflected light), or light transmitted through the inside of the fingertip (transmitted light). These new technologies may enable clinicians to monitor peripheral perfusion status more accurately and may increase the potential for ubiquitous hemodynamic monitoring across different clinical settings. This review will summarize the different methods available for peripheral perfusion monitoring and will discuss the advantages and disadvantages of each approach.

Pulse oximetry-based capillary refilling evaluation predicts postoperative outcomes in liver transplantation: a prospective observational cohort study

Background

Capillary refill time (CRT) is a non-invasive technique to evaluate tissue perfusion, and quantitative CRT (Q-CRT) adapted to pulse oximetry was developed with patients with sepsis and compared to blood lactate and sepsis scores. In post liver transplantation, large amounts of fluid administration are necessary for maintaining tissue perfusion to grafted liver against intravascular hypovolemia. This study aimed to evaluate whether Q-CRT can predict poor outcomes by detecting peripheral tissue perfusion abnormality in patients with liver transplantations who were treated with massive fluid administration.

Methods

In this single-center prospective cohort study, we enrolled adult patients with liver transplantations between June 2018 and July 2019. Measurement of Q-CRT was conducted at intensive care units (ICU) admission and postoperative day 1 (POD1).

Results

A total of 33 patients with liver transplantations were enrolled. Significant correlations of Q-CRT and ΔA_b, a tissue oxygen delivery parameter calculated by pulse oximetry data, at ICU admission with the postoperative outcomes such as length of ICU and hospital stay and total amount of ascitic fluid discharge were observed. Quantitative CRT and ΔA_b at ICU admission were significantly associated with these postoperative outcomes, even after adjusting preoperative and operative factors (MELD score and bleeding volume, respectively). However, quantitative CRT and ΔA_b at POD1 and changes from ICU admission to POD1 failed to show significant associations.

Conclusions

Q-CRT values were significantly associated with postoperative outcomes in liver transplantation. Although the mechanisms of this association need to be clarified further, Q-CRT may enable identification of high-risk patients that need intensive postoperative managements.

Capillary refill time as part of an early warning score for rapid response team activation is an independent predictor of outcomes

BACKGROUND

Capillary refill time (CRT) is easy, quick to perform and when prolonged in critical illness, correlates with progression of organ failure and mortality. It is utilized in our hospital's early warning score (EWS) as one of 11 parameters. We sought to define CRT's value in predicting patient outcomes, compared to the remaining EWS elements.

METHODS

Five-year prospective observational study of 6480 consecutive Rapid Response Team (RRT) patients. CRT measured at the index finger was considered prolonged if time to previous-color return was >3 s. We analyzed the odds ratio of normal vs prolonged-CRT, compared to the other EWS variables, to individual and combined outcomes of mortality, cardiac arrest and higher-level of care transfer.

RESULTS

Twenty-percent (N = 1329) of RRT-patients had prolonged-CRT (vs normal-CRT), were twice as likely to die (36% vs 17.8%, p < .001), more likely to experience the combined outcome (72.1% vs 54.2%, p < .001) and had longer hospital length of stays, 15.3 (SD 0.3) vs 13.5 days (SD 0.5) (p < .001). Multivariable logistic regression for mortality ranked CRT second to hypoxia among all 11 variables evaluated (p < 001).

CONCLUSIONS

This is the first time CRT has been evaluated in RRT patients. Its measurement is easy to perform and proves useful as an assessment of adult patients at-risk for clinical decline. Its prolongation in our population was an independent predictor of mortality and the combined outcome. This study and others suggest that CRT should be considered further as a fundamental assessment of patients at-risk for clinical decline.