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.

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.

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.

Calibrated versus uncalibrated arterial pressure waveform analysis in monitoring cardiac output with transpulmonary thermodilution in patients with severe sepsis and septic shock: an observational study.

BACKGROUND: Cardiac output (CO) measurement is often required in critically ill patients. The performances of newer, less invasive techniques require evaluation in patients with severe sepsis and septic shock. OBJECTIVES: To compare calibrated arterial pressure waveform analysis-derived CO (COap, VolumeView/EV1000) and the uncalibrated form (COfv, FloTrac/Vigileo) with transpulmonary thermodilution derived CO (COtptd). DESIGN: A prospective, observational, single-centre study. SETTING: ICU of a general teaching hospital. PATIENTS: Twenty consecutive patients with severe sepsis or septic shock requiring haemodynamic monitoring by VolumeView/EV1000 and receiving mechanical ventilation. INTERVENTION: Connection of FloTrac/Vigileo to radial artery catheter already in situ. MAIN OUTCOME MEASURES: Radial (COfv) and femoral (COap) arterial waveform-derived CO measurements were compared with COtptd with respect to bias, precision, limits of agreement and percentage error, and the percentage error in the course of time since the last calibration of COap by COtptd. RESULTS: In comparing COap with COtptd (n = 267 paired measurements), the bias was 0.02 and limits of agreement were -2.49 to 2.52 l min, with a percentage error of 31%. The percentage error between COap and COtptd remained less than 30% until 8 h after calibration. In comparing COfv with COtptd (n = 301), the bias was -0.86 l min and limits of agreement were -4.48 to 2.77 l min, with a percentage error of 48%. The biases of COap and COfv correlated with systemic vascular resistance [r = 0.13 (P = 0.029) and r = 0.42 (P < 0.001), respectively]. Clinically significant changes in COap and COfv correlated positively with COtptd at r = 0.51 (P < 0.001) and r = 0.64 (P < 0.001), respectively. CONCLUSION: There was moderate agreement when measuring CO with either arterial waveform analysis technique. Compared with the uncalibrated COfv, the recently introduced calibrated arterial pressure waveform analysis-derived COap was more accurate and less dependent on vascular tone for up to 8 hours after callibation when monitoring CO in patients with severe sepsis and septic shock. The COap and COfv methods have poor to moderate CO-tracking abilities.

Cardiac output measured by uncalibrated arterial pressure waveform analysis by recently released software version 3.02 versus thermodilution in septic shock.

To evaluate the 3.02 software version of the FloTrac/Vigileo™ system for estimation of cardiac output by uncalibrated arterial pressure waveform analysis, in septic shock. Nineteen consecutive patients in septic shock were studied. FloTrac/Vigileo™ measurements (COfv) were compared with pulmonary artery catheter thermodilution-derived cardiac output (COtd). The mean cardiac output was 7.7 L min(-1) and measurements correlated at r = 0.53 (P < 0.001, n = 314). In Bland-Altman plot for repeated measurements, the bias was 1.7 L min(-1) and 95 % limits of agreement (LA) were -3.0 to 6.5 L min(-1), with a %error of 53 %. The bias of COfv inversely related to systemic vascular resistance (SVR) (r = -0.54, P < 0.001). Above a SVR of 700 dyn s cm(-5) (n = 74), bias was 0.3 L min(-1) and 95 % LA were -1.6 to 2.2 L min(-1) (%error 32 %). Changes between consecutive measurements (n = 295) correlated at 0.67 (P < 0.001), with a bias of 0.1 % (95 % limits of agreement -17.5 to 17.0 %). All changes >10 % in both COtd and COfv (n = 46) were in the same direction. Eighty-five percent of the measurements were within the 30°-330° of the polar axis. COfv with the latest software still underestimates COtd at low SVR in septic shock. The tracking capacities of the 3.02 software are moderate-good when clinically relevant changes are considered.

Feasibility of HEMS performed prehospital extracorporeal-cardiopulmonary resuscitation in paediatric cardiac arrests; two case reports.

INTRODUCTION: A broad range of pathophysiologic conditions can lead to cardiopulmonary arrest in children. Some of these children suffer from refractory cardiac arrest, not responding to basic and advanced life support. Extracorporeal-Cardiopulmonary Resuscitation (E-CPR) might be a life-saving option for this group. Currently this therapy is only performed in-hospital, often necessitating long transport times, thereby negatively impacting eligibility and chances of survival. We present the first two cases of prehospital E-CPR in children performed by regular Helicopter Emergency Medical Services (HEMS). CASE PRESENTATIONS: The first patient was a previously healthy 7 year old boy who was feeling unwell for a couple of days due to influenza. His course deteriorated into a witnessed collapse. Direct bystander CPR and subsequent ambulance advanced life support was unsuccessful in establishing a perfusing rhythm. While doing chest compressions, the patient was seen moving both his arms and making spontaneous breathing efforts. Echocardiography however revealed a severe left ventricular impairment (near standstill). The second patient was a 15 year old girl, known with bronchial asthma and poor medication compliance. She suffered yet another asthmatic attack, so severe that she progressed into cardiac arrest in front of the attending ambulance and HEMS crews. Despite maximum bronchodilator therapy, intubation and the exclusion of tension pneumothoraxes and dynamic hyperinflation, no cardiac output was achieved. INTERVENTION: After consultation with the nearest paediatric E-CPR facilities, both patients were on-scene cannulated by regular HEMS. The femoral artery and vein were cannulated (15-17Fr and 21Fr respectively) under direct ultrasound guidance using an out-of-plane Seldinger approach. Extracorporeal Life Support flow of 2.1 and 3.8 l/min was established in 20 and 16 min respectively (including preparation and cannulation). Both patients were transported uneventfully to the nearest paediatric intensive care with spontaneous breathing efforts and reactive pupils during transport. CONCLUSION: This case-series shows that a properly trained regular HEMS crew of only two health care professionals (doctor and flight nurse) can establish E-CPR on-scene in (older) children. Ambulance transport with ongoing CPR is challenging, even more so in children since transportation times tend to be longer compared to adults and automatic chest compression devices are often unsuitable and/or unapproved for children. Prehospital cannulation of susceptible E-CPR candidates has the potential to reduce low-flow time and offer E-CPR therapy to a wider group of children suffering refractory cardiac arrest.

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.

Hemodynamic changes during a combined psoas compartment-sciatic nerve block for elective orthopedic surgery.

BACKGROUND: Hemodynamic variables can theoretically be influenced by a combined psoas compartment-sciatic nerve block (CPCSNB) owing to a relatively high systemic absorption of local anesthetics and extended vasodilatation in the anesthetized limb (hemisympatectomy). In this study we assessed and documented hemodynamic changes during CPCSNB for elective orthopedic surgery. METHODS: Twenty consecutive patients scheduled for a total hip arthroplasty revision surgery were subjected to a CPCSNB with 150 mg bupivacaine (with epinephrine 1:200.000) 90 minutes before surgery (2 separate single-injection blocks: 30 mg bupivacaine for the sciatic nerve block and 120 mg bupivacaine for the psoas compartment block). Cardiac index, invasive arterial blood pressure, and heart rate were measured at baseline and 60 minutes after puncture using a minimally invasive cardiac output monitoring device (FloTrac/Vigileo™ system (Edwards Lifesciences, Irvine, CA)). RESULTS: Cardiac index did not change after a CPCSNB (preblock cardiac index 2.98 ± 0.54 l · min(-1) · m(-2) versus postblock cardiac index 2.99 ± 0.60 l · min(-1) · m(-2)). There was a significant reduction in mean arterial blood pressure (108 ± 16 mm|Hg vs. 99 ± 16 mm|Hg (P < 0.001)) and diastolic blood pressure (75 ± 9 mm|Hg vs. 68 ± 10 mm|Hg (P = 0.001)). Heart rate increased significantly (68 ± 9 beats · min(-1) vs. 73 ± 10 beats · min(-1) (P = 0.001)). CONCLUSION: CPCSNB did not affect cardiac index. Changes in arterial blood pressure and heart rate, although statistically significant, remained within an acceptable clinical range (<10% variation). CPCSNB does not appear to induce clinically significant hemodynamic changes in this group of patients.

The impact of open versus closed format ICU admission practices on the outcome of high risk surgical patients: a cohort analysis.

BACKGROUND: In the year 2000, the organizational structure of the ICU in the Zaandam Medical Centre (ZMC) changed from an open to a closed format ICU. The objective of this study was to evaluate the effect of this organizational change on outcome in high risk surgical patients. METHODS: The medical records of all consecutive high risk surgical patients admitted to the ICU from 1996 to 1998 (open format) and from 2003 to 2005 (closed format), were reviewed. High-risk patients were defined according to the Identification of Risk in Surgical patients (IRIS) score. Parameters studied were: mortality, morbidity, ICU length of stay (LOS) and hospital LOS. RESULTS: Mortality of ICU patients was 25.7% in the open format group and 15.8% in the closed format group (p = 0.01). Morbidity decreased from 48.6% to 46.1% (p = 0.6). The average length of hospital stay was 17 days in the open format group, and 21 days in the closed format group (p = 0.03). CONCLUSIONS: High risk surgical patients in the ICU are patients that have undergone complex and often extensive surgery. These patients are in need of specialized treatment and careful monitoring for maximum safety and optimal care. Our results suggest that closed format is a more favourable setting than open format to minimize the effects of high risk surgery, and to warrant safe outcome in this patient group.

An Approved Landing Site (ALS) improves the logistics of interhospital transfer of critically ill patients by helicopter.

The COVID-19 pandemic limited hospital resources and necessitated interhospital transport of ICU-patients in order to provide critical care to all patients in the Netherlands. However, not all hospitals have an approved landing site. The ICU-transport operation was executed under HEMS-license and landing on non-aerodrome terrain was permitted. This allowed the search for an ad-hoc landing site in the direct vicinity of the ICU. The following characteristics were judged: slope, obstacles, size, soil conditions and the presence of foreign objects.Before the start of this transport operation, in two days, all hospitals in the Netherlands were visited and presumed landing sites explored, described, photographed and recorded in the electronic flight bag. At 71 (87,6 %) of the hospitals it was possible to install a temporary approved landing site in the direct vicinity of the ICU. 110 landings were made on these landing sites and 114 landings on approved heliports. Only 11 patients required secondary transport to or from the helicopter landings site. This occurred only in two patients from a heliport to a receiving hospital.The construction of pre-explored approved landing sites in the vicinity of hospitals allows safe transportation of patients by helicopter to hospitals without a heliport.

Four different methods of measuring cardiac index during cytoreductive surgery and hyperthermic intraperitoneal chemotherapy.

BACKGROUND: Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) are high-risk extensive abdominal surgery. During high-risk surgery, less invasive methods for cardiac index (CI) measurement have been widely used in operating theater. We investigated the accuracy of CI derived from different methods (FroTrac, ProAQT, ClearSight, and arterial pressure waveform analysis [APWA], from PICCO) and compared them to transpulmonary thermodilution (TPTD) during CRS and HIPEC in the operative room and intensive care unit (ICU). METHODS: Twenty-five patients scheduled for CRS-HIPEC were enrolled. During nine predefined time-points, simultaneous hemodynamic measurements were performed in the operating room and ICU. Absolute and relative changes of CI were analyzed using a Bland-Altman plot, four-quadrant plot, and interchangeability. RESULTS: The mean bias was -0.1 L/min/m2 for ClearSight, ProAQT, and APWA and was -0.2 L/min/m2 for FloTrac compared with TPTD. All devices had large limits of agreement (LoA). The percentage of errors and interchangeabilities for ClearSight, FloTrac, ProAQT, and APWA were 50%, 50%, 54%, 36% and 36%, 47%, 40%, 72%, respectively. Trending capabilities expressed as concordance using clinically significant CI changes were -7º ± 39º, -19º ± 38º, -13º ± 41º, and -15º ± 39º. Interchangeability in trending showed low percentages of interchangeable and gray zone data pairs for all devices. CONCLUSIONS: During CRS-HIPEC, ClearSight, FloTrac and ProAQT systems were not able to reliably measure CI compared to TPTD. Reproducibility of changes over time using concordance, angular bias, radial LoA, and interchangeability in trending of all devices was unsatisfactory.