Diffuse Reflectance Spectroscopy: Getting the Capillary Refill Test Under One's Thumb

Measurement of capillary refill time with a handheld prototype device: a comparative validation study in healthy volunteers

Validity and reproducibility of clinical capillary refill time (CRT) measurement depend on many factors in daily routine practice. We conducted a prospective validation study of an automatized handheld prototype device providing standardized CRT assessment (DiCART™) in 20 healthy volunteers. Three different methods of CRT measurement were compared before and during dynamic circulatory changes induced by venous and arterial occlusion tests at both upper and lower limb levels: CRT_CLIN corresponding to basic clinical assessment and considered as the reference method; CRT_VIDEO corresponding to off-line videos reviewed by investigators recorded by DiCART™; and CRT_DiCART corresponding to on-line videos analysed by a built-in proprietary mathematical algorithm included in DiCART™. Five subjects were excluded because of a DiCART™ dysfunction. ROC_AUC to detect arterial occlusion test changes at the upper limb level were 1.00 (95%CI 1.00; 1.00), 0.96 (95%CI 0.88; 1.00), and 0.92 (95%CI 0.79; 1.00) for CRT_CLIN, CRT_VIDEO, and CRT_DiCART, respectively. Precision of CRT_CLIN and CRT_VIDEO were significantly better than CRT_DiCART (0.18 and 0.20 vs. 0.28; P < 0.05). Percentages of error were 76% and 87% for CRT_VIDEO and CRT_DiCART, respectively. DiCART™ had an excellent discrimination to detect major changes in CRT induced by arterial ischemia. However, the perfectible precision, the poor agreement with clinical assessment and numerous device dysfunctions give leads to the development of a further version of the prototype before promoting its use in clinical practice.Trial registration clinicaltrial.gov. Identifier: NCT04538612.

Man versus machine: comparison of naked-eye estimation and quantified capillary refill

Background

Capillary refill (CR) time is traditionally assessed by ‘naked-eye’ inspection of the return to original colour of a tissue after blanching pressure. Few studies have addressed intra-observer reliability or used objective quantification techniques to assess time to original colour. This study compares naked-eye assessment with quantified CR (qCR) time using polarisation spectroscopy and examines intra-observer and interobserver agreements in using the naked eye.

Method

A film of 18 CR tests (shown in a random fixed order) performed in healthy adults was assessed by a convenience sample of 14 doctors, 15 nurses and 19 secretaries (Department of Emergency Medicine, Linköping University, September to November 2017), who were asked to estimate the time to return to colour and characterise it as ‘fast’, ‘normal’ or ‘slow’. The qCR times and corresponding naked-eye time assessments were compared using the Kruskal-Wallis test. Three videos were shown twice without observers’ knowledge to measure intra-observer repeatability. Intra-observer categorical assessments were compared using Cohen’s Kappa analysis. Interobserver repeatability was measured and depicted with multiple-observer Bland-Altman plotting. Differences in naked-eye estimation between professions were analysed using ANOVA.

Results

Naked-eye assessed CR time and qCR time differ substantially, and agreement for the categorical assessments (naked-eye assessment vs qCR classification) was poor (Cohen’s kappa 0.27). Bland-Altman intra-observer repeatability ranged from 6% to 60%. Interobserver agreement was low as shown by the Bland-Altman plotting with a 95% limit of agreement with the mean of ±1.98 s for doctors, ±1.6 s for nurses and ±1.75 s for secretaries. The difference in CR time estimation (in seconds) between professions was not significant.

Conclusions

Our study suggests that naked-eye-assessed CR time shows poor reproducibility, even by the same observers, and differs from an objective measure of CR time.

Wireless vitals-Proof of concept for wireless patient monitoring in an emergency department setting

Vital sign assessment is a common task in emergency medicine, but resources for continuous monitoring are restricted, data is often recorded manually, and entangled wires cause frustration. Therefore, we designed a small, wireless photoplethysmographic device capable of continuously assessing pulse, respiratory frequency and oxygen saturation on the sternum and tested the performance and feasibility in an emergency department setting. Fifty (56.3 ± 20.2 years), consenting emergency patients (29 male) were recruited. Heart rate, respiratory rate and oxygen saturation were recorded simultaneously using the device and standard monitoring equipment. Data was compared using Bland-Altman plotting (heart rate, respiratory rate) and mean difference (oxygen saturation). The bias for heart- and respiratory rate was 0.4 (limits of agreements -11.3, 12.2 and -6.1, 7.0). Mean difference for oxygen saturation was -0.21 ± 2.35%. This may be the first wireless device to use photoplethysmography on the sternum for vital sign assessment. We noted good agreement with standard monitors, but lack of standardization in data processing between monitoring systems may limit the generalizability of these findings. Although further improvements are needed, the feasibility of this approach provides proof of concept for a new paradigm of large scale, wireless patient monitoring.

Pediatric Dehydration Assessment at Triage: Prospective Study on Refilling Time

PURPOSE

Dehydration is a paediatric medical emergency but there is no single standard parameter to evaluate it at the emergency department. Our aim was to evaluate the reliability and validity of capillary refilling time as a triage parameter to assess dehydration in children.

METHODS

This was a prospective pilot cohort study of children who presented to two paediatric emergency departments in Italy, with symptoms of dehydration. Reliability was assessed by comparing the triage nurse's measurements with those obtained by the physician. Validity was demonstrated by using 6 parameters suggestive of dehydration. Comparison between refilling time (RT) and a validated Clinical Dehydration Score (CDS) was also considered. The scale's discriminative ability was evaluated for the outcome of starting intravenous rehydration therapy by using a receiver operating characteristic (ROC) curve.

RESULTS

Participants were 242 children. All nurses found easy to elicit the RT after being trained. Interobserver reliability was fair, with a Cohen's kappa of 0.56 (95% confidence interval [CI], 0.41 to 0.70). There was a significant correlation between RT and weight loss percentage (r-squared=-0.27; 95% CI, -0.47 to -0.04). The scale's discriminative ability yielded an area under the ROC curve (AUC) of 0.65 (95% CI, 0.57 to 0.73). We found a similarity between RT AUC and CDS-scale AUC matching the two ROC curves.

CONCLUSION

The study showed that RT represents a fast and handy tool to recognize dehydrated children who need a prompt rehydration and may be introduced in the triage line-up.