Portable Blood (Gas) Analyzer in a Helicopter Emergency Medical Service

Utilization of Multi-Parameter Blood Gas Analysis in Prehospital Emergency Medicine-A Scoping Review

BACKGROUND

Prehospital blood gas analysis (BGA) is an evolving field that offers the potential for early identification and management of critically ill patients. However, the utility and accuracy of prehospital BGA are subjects of ongoing debate.

OBJECTIVES

We aimed to provide a comprehensive summary of the current literature on prehospital BGA, including its indications, methods, and feasibility.

METHODS

We performed a scoping review of prehospital BGA. A thorough search of the PubMed, Embase, and Web of Science databases was conducted to identify relevant studies focusing on prehospital BGA in adult patients.

RESULTS

Fifteen studies met the inclusion criteria. Prehospital BGA was most frequently performed in patients in out-of-hospital cardiac arrest, followed by traumatic and nontraumatic cases. The parameters most commonly analyzed were pH, pCO2, pO2, and lactate. Various sampling methods, including arterial, venous, and intraosseous, were reported for prehospital BGA. While prehospital BGA shows promise in facilitating early identification of critical patients and guiding resuscitation efforts, logistical challenges are to be considered. The handling of preclinical BGA is described as feasible and useful in most of the included studies.

CONCLUSION

Prehospital BGA holds significant potential for enhancing patient care in the prehospital setting, though technical challenges need to be considered. However, further research is required to establish optimal indications and demonstrate the benefits for prehospital BGA in specific clinical contexts.

GFAP point-of-care measurement for prehospital diagnosis of intracranial hemorrhage in acute coma

BACKGROUND

Prehospital triage and treatment of patients with acute coma is challenging for rescue services, as the underlying pathological conditions are highly heterogenous. Recently, glial fibrillary acidic protein (GFAP) has been identified as a biomarker of intracranial hemorrhage. The aim of this prospective study was to test whether prehospital GFAP measurements on a point-of-care device have the potential to rapidly differentiate intracranial hemorrhage from other causes of acute coma.

METHODS

This study was conducted at the RKH Klinikum Ludwigsburg, a tertiary care hospital in the northern vicinity of Stuttgart, Germany. Patients who were admitted to the emergency department with the prehospital diagnosis of acute coma (Glasgow Coma Scale scores between 3 and 8) were enrolled prospectively. Blood samples were collected in the prehospital phase. Plasma GFAP measurements were performed on the i-STAT Alinity® (Abbott) device (duration of analysis 15 min) shortly after hospital admission.

RESULTS

143 patients were enrolled (mean age 65 ± 20 years, 42.7% female). GFAP plasma concentrations were strongly elevated in patients with intracranial hemorrhage (n = 51) compared to all other coma etiologies (3352 pg/mL [IQR 613-10001] vs. 43 pg/mL [IQR 29-91.25], p < 0.001). When using an optimal cut-off value of 101 pg/mL, sensitivity for identifying intracranial hemorrhage was 94.1% (specificity 78.9%, positive predictive value 71.6%, negative predictive value 95.9%). In-hospital mortality risk was associated with prehospital GFAP values.

CONCLUSION

Increased GFAP plasma concentrations in patients with acute coma identify intracranial hemorrhage with high diagnostic accuracy. Prehospital GFAP measurements on a point-of-care platform allow rapid stratification according to the underlying cause of coma by rescue services. This could have major impact on triage and management of these critically ill patients.

A Multichannel Portable Platform With Embedded Thermal Management for Miniaturized Dielectric Blood Coagulometry

This article presents a standalone, multichannel, miniaturized impedance analyzer (MIA) system for dielectric blood coagulometry measurements with a microfluidic sensor termed ClotChip. The system incorporates a front-end interface board for 4-channel impedance measurements at an excitation frequency of 1 MHz, an integrated resistive heater formed by a pair of printed-circuit board (PCB) traces to keep the blood sample near a physiologic temperature of 37 °C, a software-defined instrument module for signal generation and data acquisition, and a Raspberry Pi-based embedded computer with 7-inch touchscreen display for signal processing and user interface. When measuring fixed test impedances across all four channels, the MIA system exhibits an excellent agreement with a benchtop impedance analyzer, with rms errors of ≤0.30% over a capacitance range of 47-330 pF and ≤0.35% over a conductance range of 2.13-10 mS. Using in vitro-modified human whole blood samples, the two ClotChip output parameters, namely, the time to reach a permittivity peak (Tpeak) and maximum change in permittivity after the peak (Δϵr,max) are assessed by the MIA system and benchmarked against the corresponding parameters of a rotational thromboelastometry (ROTEM) assay. Tpeak exhibits a very strong positive correlation (r = 0.98, p < 10-6, n = 20) with the ROTEM clotting time (CT) parameter, while Δϵr,max exhibits a very strong positive correlation (r = 0.92, p < 10-6, n = 20) with the ROTEM maximum clot firmness (MCF) parameter. This work shows the potential of the MIA system as a standalone, multichannel, portable platform for comprehensive assessment of hemostasis at the point-of-care/point-of-injury (POC/POI).

A review of temperature-related challenges and solutions for the Abbott i-STAT and Siemens Healthineers epoc devices

The Abbott i-STAT and Siemens Healthineers epoc are commonly used in the provision of care during emergency medical services calls and other settings. Maintaining these systems within manufacturer's temperature claims in these settings poses challenges across the world. This review summarizes solutions that have been reported in the peer-reviewed literature and proposes additional strategies to further address these challenges. A literature search was performed with Clarivate's Web of Science from inception to August 3, 2022. Search terms included i-STAT, epoc, temperature, cold, hot, heat, freeze, frozen, prehospital, disaster, POCT, point of care, blood gas, helicopter, airplane, and ambulance. One author also reviewed manually every issue of the Journal of Paramedic Practice. The search identified 17 solutions for addressing temperature-related challenges with the i-STAT device, nine solutions for i-STAT cartridges, one solution for the epoc device, and one solution for the epoc test card. The majority of solutions were highly portable and consisted of widely available, inexpensive components. The solutions demonstrated only partial or entirely questionable effectiveness in achieving temperature control. The search also identified five reports on the impact of storage temperatures on cartridges and test cards. The reports suggested that these reagents may be able to withstand storage at temperatures outside of manufacturer's claims with only minimal deterioration in performance. The heterogeneity of solutions and the paucity of evidence on their effectiveness suggest that additional strategies are needed to better understand and further address temperature-related challenges with these systems. A collaborative approach and shared decision making are recommended.

Implementation and challenges of portable blood gas measurements in air medical transport

OBJECTIVES

Ventilator management in prehospital settings using end-tidal CO₂ can lead to inappropriate ventilation in the absence of point of care blood gas (POCBG) measurements. Implementation of POCBG testing in helicopter Emergency Medical Services (HEMS) is limited in part because of concern for preanalytical and analytical errors due to altitude, vibration, and other associated environmental factors and due to insufficient documentation of implementation challenges.

METHODS

We performed accuracy and precision verification studies using standard materials tested pre-, in-, and post-flight (n=10) in a large HEMS agency. Quality assurance error log data were extracted and summarized for common POCBG errors during the first 31 months of use and air medical transport personnel were surveyed regarding POCBG use (n=63).

RESULTS

No clinically significant differences were found between pre-, in-, and post-flight blood gas measurements. Error log data demonstrated a reduction in device errors over time. Survey participants found troubleshooting device errors and learning new clinical processes to be the largest barriers to implementation. Continued challenges for participants coincided with error log data including temperature and sampling difficulties. Survey participants indicated that POCBG testing improved patient management.

CONCLUSIONS

POCBG testing does not appear to be compromised by the HEMS environment. Temperature excursions can be reduced by use of insulated transport bags with heating and cooling packs. Availability of POCBG results in air medical transport appeared to improve ventilator management, increase recognition of ventilation-perfusion mismatch, and improve patient tolerance of ventilation.

Arterial Blood Gas and Rotational Thromboelastometry Parameters in Healthy Rescuers Incidentally Exposed to Nitroglycerin, Nitrogen Compounds, and Combustion Products

INTRODUCTION

Acute exposure to nitrogen compounds combined with a massive inhalation of air pollutants can influence respiratory and cardiovascular symptoms and coagulation abnormalities in accidentally exposed healthy adults during cave detonation operations.

METHODS

Italian alpine and cave rescuers widened a cave in the Abisso Luca Kralj in Trieste, Italy. Volunteers inside the cave were accidentally exposed to the fumes from an uncontrolled detonation of blasting gelatin microcharges. We performed a retrospective cohort study on the clinical data, arterial blood gas analysis, and rotational thromboelastometry parameters from the rescuers involved in the accident.

RESULTS

Ninety-three healthy rescuers were involved in the uncontrolled detonation: 47 volunteers handled a mixture of nitrogen compounds (blaster group), and 46 volunteers did not (nonblaster group). After the accident, statistically significant differences (P<0.05) in arterial blood gas values were observed between the groups, with a pattern of mild respiratory acidosis with hypercapnia in the nonblaster group and severe mixed acid-base disorder with hypoxia and hypercapnia in the blaster group. Mild hyperfibrinolysis was observed in 44 volunteers in the blaster group, as were associated bleeding symptoms in 34 volunteers; no significant coagulation modifications were recorded in the nonblaster group.

CONCLUSIONS

Respiratory acidosis with hypoxia, hypercapnia, a compensatory metabolic response, and mild hyperfibrinolysis were probably related to the combined effect of nitrogen compounds and the inhaled toxic products of detonation. Therefore, each element exerts a determinant effect on promoting the biological toxicity of the others.

Validation of a Point-of-Care Analyzer for Determining Anticoagulation Status During Air Transport

OBJECTIVE

We evaluated a point-of-care prothrombin time (PT)/international normalized ratio (INR) cartridge-based analyzer for its feasibility, accuracy, and value in critical care air transport.

METHODS

In this prospective study, blood samples from 10 randomly selected adult patients were tested with the cartridge during transport to determine feasibility. The cartridge results were compared with the laboratory results for the same samples. Similarly, blood samples from an additional 20 randomly selected adult patients were tested to determine test accuracy. A chart review identified 110 adult patients with PT/INR cartridge results to determine the clinical value of those results.

RESULTS

Data from the first group of 10 patients showed that vibration did not affect use of the cartridge. The average bias between the 2 testing methods was 0.0 INR units. A comparison of the PT/INR cartridge results and the laboratory results from the group of 20 patients showed that 73% of the cartridge values were within 0.2 of the laboratory values, 83% were within 0.4, and 93% were within 0.6. Of the 110 patients whose charts showed PT/INR cartridge results, 23% received blood products (45 trauma patients and 65 medical patients).

CONCLUSION

The PT/INR cartridge withstands the rigors of rotor wing transport and provides accurate, valuable results for making clinical decisions.

Incidence of hyperoxia in trauma patients receiving pre-hospital emergency anaesthesia: results of a 5-year retrospective analysis

Background

Previous studies have demonstrated an association between hyperoxia and increased mortality in various patient groups. Critically unwell and injured patients are routinely given high concentration oxygen in the pre-hospital phase of care. We aim to investigate the incidence of hyperoxia in major trauma patients receiving pre-hospital emergency anesthesia (PHEA) in the pre-hospital setting and determine factors that may help guide clinicians with pre-hospital oxygen administration in these patients.

Methods

A retrospective cohort study was performed of all patients who received PHEA by a single helicopter emergency medical service (HEMS) between 1 October 2014 and 1 May 2019 and who were subsequently transferred to one major trauma centre (MTC). Patient and treatment factors were collected from the electronic patient records of the HEMS service and the MTC. Hyperoxia was defined as a PaO₂ > 16 kPA on the first arterial blood gas analysis upon arrival in the MTC.

Results

On arrival in the MTC, the majority of the patients (90/147, 61.2%) had severe hyperoxia, whereas 30 patients (20.4%) had mild hyperoxia and 26 patients (19.7%) had normoxia. Only 1 patient (0.7%) had hypoxia. The median PaO₂ on the first arterial blood gas analysis (ABGA) after HEMS handover was 36.7 [IQR 18.5–52.2] kPa, with a range of 7.0–86.0 kPa. SpO₂ pulse oximetry readings before handover were independently associated with the presence of hyperoxia. An SpO₂ ≥ 97% was associated with a significantly increased odds of hyperoxia (OR 3.99 [1.58–10.08]), and had a sensitivity of 86.7% [79.1–92.4], a specificity of 37.9% [20.7–57.8], a positive predictive value of 84.5% [70.2–87.9] and a negative predictive value of 42.3% [27.4–58.7] for the presence of hyperoxemia.

Conclusion

Trauma patients who have undergone PHEA often have profound hyperoxemia upon arrival at hospital. In the pre-hospital setting, where arterial blood gas analysis is not readily available a titrated approach to oxygen therapy should be considered to reduce the incidence of potentially harmful tissue hyperoxia.

Prehospital administration of blood and plasma products

PURPOSE OF REVIEW

Posttraumatic bleeding following major trauma is life threatening for the patient and remains a major global health issue. Bleeding after major trauma is worsened by trauma-induced coagulopathy (TIC). TIC consists of acute trauma coagulopathy and resuscitation coagulopathy. The early diagnosis and management of prehospital TIC management are challenging.

RECENT FINDINGS

Concepts for early diagnosis and management of civilian prehospital TIC management are evolving. The feasibility of prehospital blood component as well as coagulation factor transfusion has been proven.

SUMMARY

Due to different national guidelines and regulations of blood component therapies there is a wide heterogeneity in concepts of prehospital damage control resuscitation. Tranexamic acid administration is widely accepted, whereas the transfusion of whole blood, blood components, or coagulations factors needs further examination in the civilian setting.

Prehospital coagulation measurement by a portable blood analyzer in a helicopter emergency medical service (HEMS)

In helicopter emergency medical services, HEMS, coagulopathy presents both in trauma (e.g. consumption of coagulation factors) and non-trauma cases (e.g. anticoagulant use). Therefore, in HEMS coagulation measurements appear promising and Prothrombin Time (PT) and derived INR are attractive variables herein. We tested the feasibility of prehospital PT/INR coagulation measurements in HEMS. This study was performed at the Dutch HEMS, using a portable blood analyzer (i-Stat®1, Abbott). PT/INR measurements were performed on (hemodiluted) author's blood, and both trauma- and non-trauma HEMS patients. Device-related benefits of the i-Stat PT/INR system were portability, speed and ease of handling. Limitations included a rather narrow operational temperature range (16-30 °C). PT/INR measurements (n = 15) were performed on hemodiluted blood, and both trauma and non-trauma patients. The PT/INR results confirmed effects of hemodilution and anticoagulation, however, most measurement results were in the normal INR-range (0.9-1.2). We conclude that prehospital PT/INR measurements, although with limitations, are feasible in HEMS operations.

Point-of-Care Diagnostics in Coagulation Management

This review provides a comprehensive and up-to-date overview of point-of-care (POC) devices most commonly used for coagulation analyses in the acute settings. Fast and reliable assessment of hemostasis is essential for the management of trauma and other bleeding patients. Routine coagulation assays are not designed to visualize the process of clot formation, and their results are obtained only after 30-90 m due to the requirements of sample preparation and the analytical process. POC devices such as viscoelastic coagulation tests, platelet function tests, blood gas analysis and other coagulometers provide new options for the assessment of hemostasis, and are important tools for an individualized, goal-directed, and factor-based substitution therapy. We give a detailed overview of the related tests, their characteristics and clinical implications. This review emphasizes the evident advantages of the speed and predictive power of POC clot measurement in the context of a goal-directed and algorithm-based therapy to improve the patient's outcome. Interpretation of viscoelastic tests is facilitated by a new visualization technology.

Pre-hospital transfusion of red blood cells. Part 1: A scoping review of current practice and transfusion triggers

OBJECTIVES

The primary aim of this scoping review is to describe the current use of pre-hospital transfusion of red blood cells (PHTRBC) and to evaluate criteria used to initiate PHTRBC. The effects on patients' outcomes will be reviewed in Part 2.

BACKGROUND

Haemorrhage is a preventable cause of death in trauma patients, and transfusion of red blood cells is increasingly used by Emergency Medical Services (EMS) for damage control resuscitation. However, there are no guidelines and little consensus on when to initiate PHTRBC.

METHODS

PubMed and Web of Science were searched through January 2019; 71 articles were included.

RESULTS

Transfusion triggers vary widely and involve vital signs, clinical signs of poor tissue perfusion, point of care measurements and pre-hospital ultrasound imaging. In particular, hypotension (most often defined as systolic blood pressure ≤ 90 mmHg), tachycardia (most often defined as heart rate ≥ 120/min), clinical signs of poor perfusion (eg, prolonged capillary refill time or changes in mental status) and injury type (ie, penetrating wounds) are common pre-hospital transfusion triggers.

CONCLUSIONS

PHTRBC is increasingly used by Emergency Medical Services, but guidelines on when to initiate transfusion are lacking. We identified the most commonly used transfusion criteria, and these findings may provide the basis for consensus-based pre-hospital transfusion protocols.