Validation of non-invasive point of care blood content analysis using the TensorTip™ MTX device: a method comparison study

OBJECTIVES

The TensorTip™ MTX is a non-invasive device designed to determine several physiological parameters with additional analysis of haemoglobin, haematocrit and blood gas analysis by interpreting blood diffusion colour of the finger skin based on spectral analysis. The aim of our study was to investigate the accuracy and precision of the TensorTip MTX in a clinical setting in comparison with routine analysis of blood samples.

METHODS

Forty-six patients, scheduled for elective surgery, were enrolled in this study. Placement of an arterial catheter had to be part of the standard of care. Measurements were performed during the perioperative period. The measurements obtained with the TensorTip MTX were compared with the results of routine analysis of the blood samples as a reference using correlation, Bland-Altman analysis and mountain plots.

RESULTS

No significant correlation was present in the measurements. Measurement of haemoglobin with the TensorTip MTX had a mean bias of 0.4 mmol/L, haematocrit's bias was 3.0 %. Bias of partial pressure of carbon dioxide and oxygen was 3.6 and 66.6 mmHg, respectively. Calculated percentage errors were 48.2 , 48.9, 39.9 and 109.0 %. Proportional bias was present in all Bland-Altman analyses. Less than 95 % of the differences fell within the pre-set limits of allowable error.

CONCLUSIONS

Non-invasive blood content analysis with the TensorTip MTX device is not equivalent to and did not correlate sufficiently with conventional laboratory analysis. None of the parameters measured showed results within the limits of allowable error. Therefore, the use of the TensorTip MTX is not recommended for perioperative care.

Perioperative Validation of the TensorTip™ MTX Device for Noninvasive Arterial Pressure Measurement: A Method Comparison Study

Background

The noninvasive TensorTip™ MTX measures blood pressure by interpreting blood diffusion color of the finger skin. In addition to blood pressure, the device is able to measure various vital signs: heart rate, oxygen saturation, stroke volume, and cardiac output. Studies about accuracy and precision thus far available have only been conducted by the manufacturer. The aim of our study was to investigate the accuracy and precision of the TensorTip MTX in comparison to invasive radial artery blood pressure values.

Methods

Forty-one patients scheduled for elective surgery were enrolled in this study. Placement of the arterial catheter had to be part of the standard of care. Once hemodynamic stable conditions were achieved, blood pressure was measured. Three measurements with the TensorTip MTX were averaged and compared with one invasive blood pressure measurement using Bland-Altman plot and error grid analysis.

Results

Systolic, diastolic, and mean blood pressure had a bias of respectively 6.2, -6.9 and 4.4 mm Hg. Corresponding standard deviation were respectively 30.1, 17.0 and 22.2. Calculated percentage errors were 47.6%, 52.9% and 52.3%. Proportional bias was present in all Bland-Altman analyses. Error grid analysis showed 61.0% of systolic blood pressure measurements, and 46.3% of mean blood pressure measurements were in the clinical acceptable zone.

Conclusions

The TensorTip MTX was not able to reliably measure blood pressure compared to blood pressure obtained with an arterial catheter and therefore, the measurement performance is not clinically acceptable. Moreover, a high malfunction rate makes the device unsuitable for use in perioperative period.

Safety during interhospital helicopter transfer of ventilated COVID-19 patients. No clinical relevant changes in vital signs including non-invasive cardiac output

Background

During the COVID-19 pandemic in The Netherlands, critically ill ventilated COVID-19 patients were transferred not only between hospitals by ambulance but also by the Helicopter Emergency Medical Service (HEMS). To date, little is known about the physiological impact of helicopter transport on critically ill patients and COVID-19 patients in particular. This study was conducted to explore the impact of inter-hospital helicopter transfer on vital signs of mechanically ventilated patients with severe COVID-19, with special focus on take-off, midflight, and landing.

Methods

All ventilated critically ill COVID-19 patients who were transported between April 2020 and June 2021 by the Dutch ‘Lifeliner 5’ HEMS team and who were fully monitored, including noninvasive cardiac output, were included in this study. Three 10-min timeframes (take-off, midflight and landing) were defined for analysis. Continuous data on the vital parameters heart rate, peripheral oxygen saturation, arterial blood pressure, end-tidal CO₂ and noninvasive cardiac output using electrical cardiometry were collected and stored at 1-min intervals. Data were analyzed for differences over time within the timeframes using one-way analysis of variance. Significant differences were checked for clinical relevance.

Results

Ninety-eight patients were included in the analysis. During take-off, an increase was noticed in cardiac output (from 6.7 to 8.2 L min⁻¹; P < 0.0001), which was determined by a decrease in systemic vascular resistance (from 1071 to 739 dyne·s·cm⁻⁵, P < 0.0001) accompanied by an increase in stroke volume (from 88.8 to 113.7 mL, P < 0.0001). Other parameters were unchanged during take-off and mid-flight. During landing, cardiac output and stroke volume slightly decreased (from 8.0 to 6.8 L min⁻¹, P < 0.0001 and from 110.1 to 84.4 mL, P < 0.0001, respectively), and total systemic vascular resistance increased (P < 0.0001). Though statistically significant, the found changes were small and not clinically relevant to the medical status of the patients as judged by the attending physicians.

Conclusions

Interhospital helicopter transfer of ventilated intensive care patients with COVID-19 can be performed safely and does not result in clinically relevant changes in vital signs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-02177-5.

Non-invasive electrical cardiometry cardiac output monitoring during prehospital helicopter emergency medical care: a feasibility study

Purpose

Introducing advanced hemodynamic monitoring might be beneficial during Helicopter Emergency Medical Service (HEMS) care. However, it should not increase the on-scene-time, it should be easy to use and should be non-invasive. The goal of this study was to investigate the feasibility of non-invasive cardiac output measurements by electrical cardiometry (EC) and the quality of the EC signal during pre-hospital care provided by our HEMS.

Methods

A convenience sample of fifty patients who required HEMS assistance were included in this study. Problems with respect to connecting the patient, entering patient characteristics and measuring were inventoried. Quality of EC signal of the measurements was assessed during prehospital helicopter care. We recorded the number of measurements with a signal quality indicator (SQI) ≥ 80 and the number of patients having at least 1 measurement with a SQI ≥ 80. Furthermore, the SQI value distribution of the measurements within each patient was analysed.

Results

In the experience of the attending HEMS caregivers application of the device was easy and did not result in increased duration of on-scene time. Patch adhesion was reported as a concern due to clammy skin in 22% of all cases. 684 measurements were recorded during HEMS care. In 47 (94%) patients at least 1 measurement with an SQI ≥ 80 was registered. Of all recorded measurements 5.8% had an SQI < 40, 11.4% had an SQI 40–59, 14.9% had a SQI between 60 and 79 and 67.8% had SQI ≥ 80.

Conclusion

Cardiac output measurements are feasible during prehospital HEMS care with good quality of the EC signal. Monitoring was easy to use and quick to install. In our view it is an promising candidate for the prehospital setting. Further research is needed to determine its clinical value during clinical decision making.

Accuracy and precision of non-invasive cardiac output monitoring by electrical cardiometry: a systematic review and meta-analysis

Cardiac output monitoring is used in critically ill and high-risk surgical patients. Intermittent pulmonary artery thermodilution and transpulmonary thermodilution, considered the gold standard, are invasive and linked to complications. Therefore, many non-invasive cardiac output devices have been developed and studied. One of those is electrical cardiometry. The results of validation studies are conflicting, which emphasize the need for definitive validation of accuracy and precision. We performed a database search of PubMed, Embase, Web of Science and the Cochrane Library of Clinical Trials to identify studies comparing cardiac output measurement by electrical cardiometry and a reference method. Pooled bias, limits of agreement (LoA) and mean percentage error (MPE) were calculated using a random-effects model. A pooled MPE of less than 30% was considered clinically acceptable. A total of 13 studies in adults (620 patients) and 11 studies in pediatrics (603 patients) were included. For adults, pooled bias was 0.03 L min^-1 [95% CI - 0.23; 0.29], LoA - 2.78 to 2.84 L min^-1 and MPE 48.0%. For pediatrics, pooled bias was - 0.02 L min^-1 [95% CI - 0.09; 0.05], LoA - 1.22 to 1.18 L min^-1 and MPE 42.0%. Inter-study heterogeneity was high for both adults (I² = 93%, p < 0.0001) and pediatrics (I² = 86%, p < 0.0001). Despite the low bias for both adults and pediatrics, the MPE was not clinically acceptable. Electrical cardiometry cannot replace thermodilution and transthoracic echocardiography for the measurement of absolute cardiac output values. Future research should explore it's clinical use and indications.