A comparison of prehospital lactate and systolic blood pressure for predicting the need for resuscitative care in trauma transported by ground

Identifying trigger cues for hospital blood transfusions based on ensemble of machine learning methods

BACKGROUND

Traumatic shock is the leading cause of preventable death with most patients dying within the first six hours from arriving to the hospital. This underscores the importance of prehospital interventions, and growing evidence suggests prehospital transfusion improves survival. Optimizing transfusion triggers in the prehospital setting is key to improving outcomes for patients in hemorrhagic shock. Our objective was to identify factors associated with early in-hospital transfusion requirements available to prehospital clinicians in the field to develop a simple algorithm for prehospital transfusion, particularly for patients with occult shock.

METHODS

We included trauma patients transported by a single critical care transport service to a level I trauma center between 2012 and 2019. We used logistic regression, Fast and Frugal Trees (FFTs), and Bayesian analysis to identify factors associated with early in-hospital blood transfusion as a potential trigger for prehospital transfusion.

RESULTS

We included 2,157 patients transported from the scene or emergency department (ED) of whom 207 (9.60%) required blood transfusion within four hours of admission. The mean age was 47 (IQR = 28 - 62) and 1,480 (68.6%) patients were male. From 13 clinically relevant factors for early hospital transfusions, four were incorporated into the FFT in following order: 1) SBP, 2) prehospital lactate concentration, 3) Shock Index, 4) AIS of chest (sensitivity = 0.81, specificity = 0.71). The chosen thresholds were similar to conventional ones. Using conventional thresholds resulted in lower model sensitivity. Consistently, prehospital lactate was among most decisive factors of hospital transfusions identified by Bayesian analysis (OR = 2.31; 95% CI 1.55 - 3.37).

CONCLUSIONS

Using an ensemble of frequentist statistics, Bayesian analysis and machine learning, we developed a simple, clinically relevant prehospital algorithm to help identify patients requiring transfusion within 4 h of hospital arrival.

The predictive value of serum lactate to forecast injury severity in trauma-patients increases taking age into account

BACKGROUND

Two-tier trauma team activation (TTA)-protocols often fail to safely identify severely injured patients. A possible amendment to existing triage scores could be the measurement of serum lactate. The aim of this study was to determine the ability of the combination of serum lactate and age to predict severe injuries (ISS > 15).

METHODS

We conducted a retrospective cohort study in a single level one trauma center in a 20 months study-period and analyzed every trauma team activation (TTA) due to the mechanism of injury (MOI). Primary endpoint was the correlation between serum lactate (and age) and ISS and mortality. The validity of lactate (LAC) and lactate contingent on age (LAC + AGE) were assessed using the area under the curve (AUC) of the receiver operating characteristics (ROC) curve. We used a logistic regression model to predict the probability of an ISS > 15.

RESULTS

During the study period we included 325 patients, 75 met exclusion criteria. Mean age was 43 years (Min.: 11, Max.: 90, SD: 18.7) with a mean ISS of 8.4 (SD: 8.99). LAC showed a sensitivity of 0.82 with a specificity of 0.62 with an optimal cutoff at 1.72 mmol/l to predict an ISS > 15. The AUC of the ROC for LAC was 0.764 (95% CI: 0.67-0.85). The LAC + AGE model provided a significantly improved predictive value compared to LAC (0.765 vs. 0.828, p < 0.001).

CONCLUSIONS

The serum lactate concentration is able to predict injury severity. The prognostic value improves significantly taking the patients age into consideration. The combination of serum lactate and age could be a suitable Ad-on to existing two-tier triage protocols to minimize undertriage.

LEVEL OF EVIDENCE

Level IV, retrospective cohort study.

Is the lactate value predictive of the return of spontaneous circulation during CPR in nontraumatic OHCA?

AIM OF THE STUDY

Cardiac arrest is a major public health issue, in which emergency medical services (EMS) initiating or continuing resuscitation in about 50% to 60% of cases. The aim of this study was to determine whether blood lactate levels and their course during cardiopulmonary resuscitation are prognostic indicators of the return of spontaneous cardiac activity (ROSC) in non-traumatic out-of-hospital cardiac arrest (OHCA).

METHODS

This was a prospective, interventional, multi-center study between 2017 and 2020. Patients above the age of 18 years (>50 years for women) who had non-traumatic OHCA and did not achieve ROSC before the arrival of the EMS, and for whom the medical team decided to initiate or continue cardiopulmonary resuscitation have been included. The primary endpoint was the return of spontaneous cardiac activity during out-of-hospital cardiopulmonary resuscitation, and secondary endpoint was survival at day 28. The lactate was initially measured simultaneously on a venous and capillary sample and then in capillary samples throughout the CPR, using POC device.

RESULTS

A total 60 patients were included. Median age was 71 [IQR: 62-84] and 21.3% were female. Among them, 25% underwent ROSC in out-of-hospital setting, and 13,3% were alive at D-28. The median venous lactate value in all patients at T0 (time at which the EMS set up the peripheral venous line) was 6.2 mmol/L [IQR: 4.6-8.1], with no difference between patients with or without ROSC: 6.4 mmol/L [IQR:4.7-7.9] for patients with ROSC and 6.2 mmol/L [IQR: 4.7-8] for patients without ROSC (p = 0.87). The variables independently associated with ROSC were initial EtCo2 value (aOR = 1.12; 95% CI 1.01-1.25); the initial shockable rhythm (aOR = 10.2; 95% CI 1.18-88.2); and the pre-ROSC adrenaline dose (aOR = 0.54; 95% CI 0.35-0.82).

CONCLUSION

In this prospective multi-center study, there was no independent association between lactate values during cardiopulmonary resuscitation and ROSC in non-traumatic OHCA. However, the post-ROSC pre-hospital kinetics of lactate (i.e., during the first 30 min) seem to be associated with survival.

Early correction of base deficit decreases late mortality in polytrauma

INTRODUCTION

Physiology-driven resuscitation has become the standard of care in severely injured patients. This has resulted in a decrease in acute deaths by hemorrhagic shock. With increased survival from hemorrhage, focus shifts towards death later during hospital stay. This population based cohort study investigated the association of initial physiology derangement correction and (late) mortality.

METHODS

Consecutive polytrauma patients aged > 15 years with deranged physiology who were admitted to a level-1 trauma center intensive care unit (ICU) from 2015 to 2021, and requiring surgical intervention < 24 h were included. Patients who acutely (< 48 h) died were excluded. Demographics, treatment, and outcome parameters were analyzed. Physiology was monitored by serial base deficits (BD) during the first 48 h. Correction of physiology was defined as BD return to normal values. Area under the curve (AUC) of BD in time was used as measurement for the correction of physiological derangement and related to mortality 3-6 days (early), and > 7 days (late).

RESULTS

Two hundred thirty-five patients were included with a median age of 44 years (70% male), and Injury Severity Score (ISS) of 33. Mortality rate was 16% (71% due to traumatic brain injury (TBI)). Median time to death was 11 (6-17) days; 71% died > 7 days after injury. There was no difference between the single base deficit measurements in the emergency department(ED), operating room (OR), nor ICU between patients who died and those who did not. However, patients who later died were more acidotic at 24 and 48 h after arrival, and had a higher AUC of BD in time. This was independent of time and cause of death.

CONCLUSION

Early physiological restoration based on serial BD measurements in the first 48 h after injury decreases late mortality.

Prehospital Time Following Traumatic Injury Is Independently Associated With the Need for In-Hospital Blood and Early Mortality for Specific Injury Types

OBJECTIVE

Treating traumatic hemorrhage is time sensitive. Prehospital care and transport modes (eg, helicopter and ground) may influence in-hospital events. We hypothesized that prehospital time (on-scene time [OST] and total prehospital time [TPT]) and transport mode are associated with same-day transfusion and mortality. Furthermore, we sought to identify regions of anatomic injury that modify the relationship between prehospital time and outcomes in strata corresponding to transport types.

METHODS

We obtained prehospital, in-hospital, and trauma registry data from an 8-center cohort of adult nonburn trauma patients from 2017 to 2022 directly transported from the scene to the hospital and having an Injury Severity Score (ISS) > 9 for the Task Order 1 project of the Linking Investigators in Trauma and Emergency Services research network. We excluded patients missing prehospital times, patients < 18 years of age, patients from interfacility transfers, and recipients of prehospital blood. Our same-day outcomes were in-hospital transfusions within 4 hours and 24-hour mortality. Each outcome was adjusted using multivariable logistic regression for covariates of prehospital phases (OST and TPT), mode of transport (helicopter and ground), age, sex, ISS, Glasgow Coma Scale motor subscale score < 6, and field hypotension (systolic blood pressure < 90 mm Hg). We evaluated the association of prehospital time on outcomes for scene missions by transport mode across severe injury patterns defined by Abbreviated Injury Scale > 2 body regions.

RESULTS

Of 78,198 subjects, 34,504 were eligible for the study with a mean age of 47.6 ± 20.3 years, ISS of 18 ± 11, OST of 15.9 ± 9.5 minutes, and TPT of 48.7 ± 20.3 minutes. Adjusted for injury severity and demographic factors, transport type significantly modified the relationship between prehospital time and outcomes. The association of OST and TPT with the odds of 4-hour transfusion was absent for the ground emergency medical services (GEMS) cohort and present for the helicopter emergency medical services (HEMS) ambulance cohort, whereas these times were associated with decreased 24-hour mortality for both transport types. When stratifying by injury to most anatomic regions, OST and TPT were associated with a decreased need for 4-hour transfusions in the GEMS cohort. However, OST was associated with increased early transfusion only among patients with severe injuries of the thorax, and this association persisted after adjusting additionally for injury type (odds ratio [OR] = 1.03; 95% confidence interval [CI], 1.00-1.05; P = .02). The presence of polytrauma supported an association between prehospital time and decreased 24-hour mortality for the GEMS cohort (OST: OR = 0.97; 95% CI, 0.95-0.99; P < .01; TPT: OR = 0.99; 95% CI, 0.98-0.99; P = .02), whereas no injuries showed significant association of helicopter prehospital time on mortality after adjustment.

CONCLUSION

We determined that transport type affects the relationship between prehospital time and hospital outcomes (4-hour transfusion: positive relationship for HEMS and negative for GEMS, 24-hour mortality: negative for both transport types). Furthermore, we identified regions of anatomic injury that modify the relationship between prehospital time and outcomes in strata corresponding to transport types. Of these regions, most notable were severe isolated injuries to the thorax that supported a positive relationship between HEMS OST and 4-hour transfusions and polytrauma that showed a negative relationship between GEMS OST or TPT and 24-hour mortality after adjustment.

Managing Hemostasis in Space

Human space travel requires exposure to weightlessness, ionizing radiation, isolation, and austerity. A recent report of internal jugular vein thrombosis in astronauts in low Earth orbit confirms that these exposures also affect vascular biology to influence diseases of thrombosis and hemostasis. This brief review summarizes the known influences of space travel on inflammation, blood coagulation, and the cardiovascular system and conceptualizes how they might combine to affect thrombosis and hemostasis. In the event of a major thrombotic or bleeding emergency, it is anticipated that the unique physiological influences of the space environment and logistical limitations of providing medical care in space would require a response that is unique from our current experience. We also look towards the future to discuss lessons learned from our current experiences on Earth and in space.

The potential of point-of-care diagnostics to optimise prehospital trauma triage: a systematic review of literature

PURPOSE

In the prehospital care of potentially seriously injured patients resource allocation adapted to injury severity (triage) is a challenging. Insufficiently specified triage algorithms lead to the unnecessary activation of a trauma team (over-triage), resulting in ineffective consumption of economic and human resources. A prehospital trauma triage algorithm must reliably identify a patient bleeding or suffering from significant brain injuries. By supplementing the prehospital triage algorithm with in-hospital established point-of-care (POC) tools the sensitivity of the prehospital triage is potentially increased. Possible POC tools are lactate measurement and sonography of the thorax, the abdomen and the vena cava, the sonographic intracranial pressure measurement and the capnometry in the spontaneously breathing patient. The aim of this review was to assess the potential and to determine diagnostic cut-off values of selected instrument-based POC tools and the integration of these findings into a modified ABCDE based triage algorithm.

METHODS

A systemic search on MEDLINE via PubMed, LIVIVO and Embase was performed for patients in an acute setting on the topic of preclinical use of the selected POC tools to identify critical cranial and peripheral bleeding and the recognition of cerebral trauma sequelae. For the determination of the final cut-off values the selected papers were assessed with the Newcastle-Ottawa scale for determining the risk of bias and according to various quality criteria to subsequently be classified as suitable or unsuitable. PROSPERO Registration: CRD 42022339193.

RESULTS

267 papers were identified as potentially relevant and processed in full text form. 61 papers were selected for the final evaluation, of which 13 papers were decisive for determining the cut-off values. Findings illustrate that a preclinical use of point-of-care diagnostic is possible. These adjuncts can provide additional information about the expected long-term clinical course of patients. Clinical outcomes like mortality, need of emergency surgery, intensive care unit stay etc. were taken into account and a hypothetic cut-off value for trauma team activation could be determined for each adjunct. The cut-off values are as follows: end-expiratory CO2: < 30 mm/hg; sonography thorax + abdomen: abnormality detected; lactate measurement: > 2 mmol/L; optic nerve diameter in sonography: > 4.7 mm.

DISCUSSION

A preliminary version of a modified triage algorithm with hypothetic cut-off values for a trauma team activation was created. However, further studies should be conducted to optimize the final cut-off values in the future. Furthermore, studies need to evaluate the practical application of the modified algorithm in terms of feasibility (e.g. duration of application, technique, etc.) and the effects of the new algorithm on over-triage. Limiting factors are the restriction with the search and the heterogeneity between the studies (e.g. varying measurement devices, techniques etc.).

Predictive clinical utility of pre-hospital point of care lactate for transfusion of blood product in patients with suspected traumatic haemorrhage: derivation of a decision-support tool

INTRODUCTION

Pre-hospital emergency medical teams can transfuse blood products to patients with suspected major traumatic haemorrhage. Common transfusion triggers based on physiological parameters have several disadvantages and are largely unvalidated in guiding pre-hospital transfusion. The addition of pre-hospital lactate (P-LACT) may overcome these challenges. To date, the clinical utility of P-LACT to guide pre-hospital blood transfusion is unclear.

METHODS

A retrospective analysis of patients with suspected major traumatic haemorrhage attended by Air Ambulance Charity Kent Surrey Sussex (KSS) between 8 July 2017 and 31 December 2019. The primary endpoint was the accuracy of P-LACT to predict the requirement for any in-hospital (continued) transfusion of blood product.

RESULTS

During the study period, 306 patients with suspected major traumatic haemorrhage were attended by KSS. P-LACT was obtained in 194 patients. In the cohort 103 (34%) patients were declared Code Red. A pre-hospital transfusion was commenced in 124 patients (41%) and in-hospital transfusion was continued in 100 (81%) of these patients, in 24 (19%) patients it was ceased. Predictive probabilities of various lactate cut-off points for requirement of in-hospital transfusion are documented. The highest overall proportion correctly classified patients were found for a P-LACT cut-point of 5.4 mmol/L (76.50% correctly classified). Based on the calculated predictive probabilities, optimal cut-off points were derived for both the exclusion- and inclusion of the need for in-hospital transfusion. A P-LACT < 2.5 mmol/L had a sensitivity of 80.28% and a negative likelihood ratio [LR-] of 0.37 for the prediction of in-hospital transfusion requirement, whereas a P-LACT of 6.0 mmol/L had a specificity of 99.22%, [LR-] = 0.78.

CONCLUSION

Pre-hospital lactate measurements can be used to predict the need for (continued) in-hospital blood products in addition to current physiological parameters. A simple decision support tool derived in this study can help the clinician interpret pre-hospital lactate results and guide pre-hospital interventions in the major trauma patient.

Injuries associated with hypotension after trauma: Is it always haemorrhage?

Introduction

Restricted fluid replacement strategy is one part of damage control resuscitation for patients with trauma haemorrhage. However, not all patients presenting with physiological symptoms suggestive of haemorrhage are bleeding. This descriptive study aims to compare demographics and injuries in adult and older trauma patients presenting to the Emergency Department with hypotension versus normotension.

Methods

This was a retrospective, descriptive data analysis from a UK trauma registry. The records from one major trauma centre were analysed between 2014–2019, and every hypotensive (systolic blood pressure <90 mmHg) trauma patient investigated for injuries associated with hypotension. The hypotensive threshold for older patients was also adjusted to 110 mmHg for sub-cohort analysis.

Results

6245 trauma patients were included, of which 255 (4.1%) arrived hypotensive at the Emergency Department. Significant blood loss was identified in 32.2% of those cases. In 27.1%, multiple potential associations obscured the underlying mechanism for the hypotension but were more commonly associated with hypotension than with normotension. Over a third (37.5%) were ≥65 years old. Neurological injuries occurred more frequently in both older hypotensive groups than younger patients.

Conclusions

This study sought to compare injuries of adult and older trauma patients to aid trauma teams with decision making. In severely injured hypotensive patients, significant blood loss was the principal association with hypotension. However, several factors can mimic bleeding in the hypotensive trauma patient, which should be carefully considered. A prospective study is needed to clarify the characteristics and causes of bleeding mimics.

Prehospital Lactate is Associated with the Need for Blood in Trauma

Background: Traumatic hemorrhage is the leading cause of preventable death, and its effects are often evident within the first 24 hours of hospital admission. We investigated the relationship between prehospital lactate measurement and administration of hospital blood products and life-saving interventions (LSIs) within 24 hours of hospital admission.Methods: We included trauma patients with recorded prehospital venous lactate transported by a single critical care transport service to a Level I trauma center between 2012 and 2019. We abstracted vital signs, mission type, anatomic location of injury, prehospital administration of crystalloid and blood products, and hospital LSIs started within 24 hours of admission. We used logistic regression to determine the association of prehospital lactate and in-hospital administration of blood products in groups with or without hypotensive patients. We investigated the effect of prehospital lactate concentration on secondary outcomes such as LSIs and mortality.Results: We included 2,170 patients transported from the scene or emergency department (ED), of whom 1,821 (84%) were normotensive. The median concentration of prehospital lactate was 2.10 mmol/L for the main population (IQR = 1.40-3.30) and 2.00 mmol/L for the normotensive subgroup (IQR = 1.30-2.90). A higher prehospital lactate concentration was associated with higher odds of needing early hospital blood products in the whole study population (OR = 1.12, (95% CI 1.06-1.20), p < 0.01) and in the normotensive subgroup (OR = 1.13, (95% CI 1.03-1.22), p = 0.01). These positive associations were also observed with the secondary outcome of hospital LSIs, and higher prehospital lactate was also associated with higher odds of mortality (OR = 1.32, (95% CI 1.20-1.45), p < 0.01).Conclusions: Higher concentrations of prehospital lactate were associated with the need for in-hospital blood transfusion within 24 hours of admission. The relationship between lactate and blood transfusion persisted among normotensive patients. Further work is needed to incorporate prehospital lactate into decision support tools for prehospital blood administration.

Elevated serum lactate levels and age are associated with an increased risk for severe injury in trauma team activation due to trauma mechanism

BACKGROUND

The identification of risk factors for severe injury is crucial in trauma triage and trauma team activation (TTA) depends on a sufficient triage. The aim of this study was to determine whether or not elevated serum lactate levels and age are risk factors for severe injury in TTA due to trauma mechanism.

METHODS

We conducted a retrospective cohort study in a single level one trauma center between September 2019 and May 2021 and analysed every TTA due to trauma mechanism. Primary endpoint of interest was the association of serum lactate as well as age with injury severity assessed by the injury severity score (ISS).

RESULTS

During the study period, we included 250 patients. Mean age was 43.3 years (Min.: 11, Max.: 90, SD: 18.7) and the initial lactate level was 1.7 mmol/L (SD: 0.95) with a mean ISS of 8.4 (SD: 8.99). The adjusted odds ratio (OR) for age > 65 being associated with an ISS > 16 is 9.7 (p < 0.001; 95% CI 4.01-25.58) and for lactate > 2.2 mmol/L being associated with an ISS > 16 is 6.29 (p < 0.001; 95% CI 2.93-13.48). A lactate level of > 4 mmol/L results in a 36-fold higher risk of severe injury with an ISS > 16 (OR 36.06; 95% CI 4-324.29).

CONCLUSION

This study identifies age (> 65) and lactate (> 2.2 mmol/L) as independent risk factors for severe injury in a TTA due to trauma mechanism. Existing triage protocols might benefit from congruous amendments.

Pre-hospital suPAR, lactate and CRP measurements for decision-making: a prospective, observational study of patients presenting non-specific complaints

Background

In the pre-hospital setting, non-urgent patients with non-specific chief complaints pose assessment challenges for the emergency medical systems (EMS). Severely ill patients should be identified among these patients, and unnecessary transport to the emergency department (ED) should be avoided. Unnecessary admissions burden EDs, deplete EMS resources and can even be harmful to patients, especially elderly patients. Therefore, tools for facilitating pre-hospital decision-making are needed. They could be based on vital signs or point-of-care laboratory biomarkers. In this study, we examined whether the biomarker soluble urokinase plasminogen activator receptor (suPAR), either alone or combined with C-reactive protein (CRP) and/or lactate, could predict discharge from the ED and act as a pre-hospital support tool for non-conveyance decision-making.

Methods

This was a prospective, observational study of adult patients with normal or near-normal vital signs transported by an EMS to an ED with a code referring to deteriorated general condition. The levels of suPAR, CRP and lactate in the patients’ pre-hospital blood samples were analysed. The values of hospitalized patients were compared to those of discharged patients to determine whether these biomarkers could predict direct discharge from the ED.

Results

A total of 109 patients (median age: 81 years) were included in the study. Of those, 52% were hospitalized and 48% were discharged from the ED. No statistically significant association was found between suPAR and the ED discharge vs hospitalization outcome (OR: 1.04, 95% CI 0.97–1.13, AUROC: 0.58, 95% CI 0.47–0.69). Adding CRP (AUROC: 0.64, 95% CI 0.54–0.75) or lactate (AUROC: 0.60, 95% CI 0.49–0.71) to the regression models did not improve their diagnostic accuracy. None of the patients with a suPAR value of less than 2 ng/ml were admitted to hospital, while 64% of the patients with a suPAR value of more than 6 ng/ml were hospitalized.

Conclusion

Pre-hospital suPAR measurements alone or combined with CRP and/or lactate measurements could not predict the ED discharge or hospital admission of 109 non-urgent EMS patients with non-specific chief complaints and normal or near-normal vital signs.

Prehospital end-tidal carbon dioxide predicts hemorrhagic shock upon emergency department arrival

BACKGROUND

In addition to reflecting gas exchange within the lungs, end-tidal carbon dioxide (ETCO2) also reflects cardiac output based on CO2 delivery to the pulmonary parenchyma. We hypothesized that low prehospital ETCO2 values would be predictive of hemorrhagic shock in intubated trauma patients.

METHODS

A retrospective observational study of adult trauma patients intubated in the prehospital setting and transported to a single Level I trauma center from 2016 to 2019. Continuous prehospital ETCO2 data were linked with patient care registries. We developed a novel analytic approach that allows for reflection of prehospital ETCO2 over the entire prehospital course of care. The primary outcome was hemorrhagic shock on emergency department (ED) presentation, defined as either initial ED systolic blood pressure of 90 mm Hg or less or initial Shock Index (SI) > 0.9, and transfusion of at least one unit of blood product during their ED stay. Prehospital ETCO2 less than 25 mm Hg was evaluated for predictive value of hemorrhagic shock.

RESULTS

Three hundred and seven patients (82% men, 34% penetrating injury, 42% in hemorrhagic shock on ED arrival, 27% mortality) were included in the study. Patients in hemorrhagic shock had lower median ETCO2 values (26.5 mm Hg vs. 32.5 mm Hg; p < 0.001) than those not in hemorrhagic shock. Patients with prehospital ETCO2 less than 25 mm Hg were 3.0 times (adjusted odds ratio = 3.0; 95% confidence interval, 1.1-7.9) more likely to be in hemorrhagic shock upon ED arrival than patients with ETCO2 ≥ 25 mm Hg.

CONCLUSION

Intubated patients with hemorrhagic shock upon ED arrival had significantly lower prehospital ETCO2 values. Incorporating ETCO2 assessment into prehospital care for trauma patients could support decisions regarding prehospital blood transfusion, and triage to higher-level trauma centers, and trauma team activation.

LEVEL OF EVIDENCE

Prognostic, level III.

Lactate as a mediator of prehospital plasma mortality reduction in hemorrhagic shock

BACKGROUND

Prehospital plasma transfusion in trauma reduces mortality. However, the underlying mechanism remains unclear. Reduction in shock severity may play a role. Lactate correlates with physiologic shock severity and mortality after injury. Our objective was to determine if prehospital plasma reduces lactate and if this contributes to the mortality benefit of plasma.

METHODS

Patients in the Prehospital Air Medical Plasma trial in the upper quartile of injury severity (Injury Severity Score, >30) were included to capture severe shock. Trial patients were randomized to prehospital plasma or standard care resuscitation (crystalloid ± packed red blood cells). Regression determined the associations between admission lactate, 30-day mortality, and plasma while adjusting for demographics, prehospital crystalloid, time, mechanism, and injury characteristics. Causal mediation analysis determined what proportion of the effect of plasma on mortality is mediated by lactate reduction.

RESULTS

A total of 125 patients were included. The plasma group had a lower adjusted admission lactate than standard of care group (coefficient, -1.64; 95% confidence interval [CI], -2.96 to -0.31; p = 0.02). Plasma was associated with lower odds of 30-day mortality (odds ratio [OR], 0.27; 95% CI, 0.08-0.90; p = 0.03). When adding lactate to this model, the effect of plasma on 30-day mortality was no longer significant (OR, 0.36; 95% CI, 0.07-1.88; p = 0.23), while lactate was associated with mortality (OR, 1.74 per 1 mmol/L increase; 95% CI, 1.10-2.73; p = 0.01). Causal mediation demonstrated 35.1% of the total effect of plasma on 30-day mortality was mediated by the reduction in lactate among plasma patients.

CONCLUSION

Prehospital plasma is associated with reduced 30-day mortality and lactate in severely injured patients. More than one third of the effect of plasma on mortality is mediated by a reduction in lactate. Thus, reducing the severity of hemorrhagic shock appears to be one mechanism of prehospital plasma benefit. Further study should elucidate other mechanisms and if a dose response exists.

LEVEL OF EVIDENCE

Therapeutic, level II.

Predicting the need for blood transfusion requirement in postpartum hemorrhage

OBJECTIVE

We aimed to assess the role of lactate and hemoglobin levels as predictors for the need for blood transfusion in post-partum hemorrhage (PPH).

METHODS

A retrospective cohort study of women with PPH in a single university-affiliated tertiary medical center between August 2018 and June 2020. PPH was defined as an estimated excessive blood loss (of more than 500 ml following vaginal delivery and 1000 ml following a cesarean delivery) requiring at least one uterotonic drug and fluid resuscitation. Women were stratified by the need of requiring blood transfusion due to hemorrhage. The criteria for blood transfusion were: (1) clinically severe uncontrollable ongoing hemorrhage; (2) symptomatic anemia (maternal tachycardia >110 beats per minute, dizziness, syncope or presyncope) in the presence of Hb 7-8 g/dL^; or (3) postpartum Hb level < 7 g/dL regardless of maternal symptoms or signs of anemia. Demographic, labor characteristics as well as laboratory data were collected. For all women the Shock Index (SI: heart rate divided by systolic blood pressure) was calculated. Women without available data on immediate (more than 15 min from the bleeding initiation) hemoglobin (Hb) level and lactate concentrations were excluded.

RESULTS

Overall, out of 22,241 deliveries during the study, 94 women were included, of them 26 (23.4%) required blood transfusion. The antepartum Hb level was lower in the transfused group (11.7 ± vs 12.4 ± 1.0 re/dL, p = .01). No significant differences were found in demographic and labor characteristics. In multivariate logistic regression analysis, a lower immediate postpartum Hb and a higher SI higher were associated with blood transfusion requirement (adjusted odds ratio (aOR) 3.45 [CI] 1.82-7.69, p < .001] and aOR 1.25 [CI 1.03-1.55, p = .03], respectively). The combination of SI, immediate postpartum Hb and lactate concentration provided the best integration, with an area under the curve of 0.86, sensitivity 92.65%, specificity 61.54%, positive and negative predictive values of 86.3% and 76.2%, respectively.

CONCLUSION

The combination of SI, immediate postpartum Hb and lactate levels is a good predictor for the need of blood requirement in PPH.

Making the call in the field: Validating emergency medical services identification of anatomic trauma triage criteria

BACKGROUND

The National Field Triage Guidelines were created to inform triage decisions by emergency medical services (EMS) providers and include eight anatomic injuries that prompt transportation to a Level I/II trauma center. It is unclear how accurately EMS providers recognize these injuries. Our objective was to compare EMS-identified anatomic triage criteria with International Classification of Diseases-10th revision (ICD-10) coding of these criteria, as well as their association with trauma center need (TCN).

METHODS

Scene patients 16 years and older in the NTDB during 2017 were included. National Field Triage Guidelines anatomic criteria were classified based on EMS documentation and ICD-10 diagnosis codes. The primary outcome was TCN, a composite of Injury Severity Score greater than 15, intensive care unit admission, urgent surgery, or emergency department death. Prevalence of anatomic criteria and their association with TCN was compared in EMS-identified versus ICD-10-coded criteria. Diagnostic performance to predict TCN was compared.

RESULTS

There were 669,795 patients analyzed. The ICD-10 coding demonstrated a greater prevalence of injury detection. Emergency medical service-identified versus ICD-10-coded anatomic criteria were less sensitive (31% vs. 59%), but more specific (91% vs. 73%) and accurate (71% vs. 68%) for predicting TCN. Emergency medical service providers demonstrated a marked reduction in false positives (9% vs. 27%) but higher rates of false negatives (69% vs. 42%) in predicting TCN from anatomic criteria. Odds of TCN were significantly greater for EMS-identified criteria (adjusted odds ratio, 4.5; 95% confidence interval, 4.46-4.58) versus ICD-10 coding (adjusted odds ratio 3.7; 95% confidence interval, 3.71-3.79). Of EMS-identified injuries, penetrating injury, flail chest, and two or more proximal long bone fractures were associated with greater TCN than ICD-10 coding.

CONCLUSION

When evaluating the anatomic criteria, EMS demonstrate greater specificity and accuracy in predicting TCN, as well as reduced false positives compared with ICD-10 coding. Emergency medical services identification is less sensitive for anatomic criteria; however, EMS identify the most clinically significant injuries. Further study is warranted to identify the most clinically important anatomic triage criteria to improve our triage protocols.

LEVEL OF EVIDENCE

Care management, Level IV; Prognostic, Level III.

Prehospital ABC Score Accurately Forecasts Patients Who Will Require Immediate Resource Utilization

OBJECTIVES

Scoring systems, such as the Assessment of Blood Consumption (ABC) Score, are used to identify patients at risk for massive transfusion (MT, ≥10 U red blood cells in 24 hours). Our aeromedical transport helicopter uses ultrasound to perform the Focused Assessment with Sonography for Trauma (FAST) examination. Our objective was to evaluate the ability of the Prehospital ABC (PhABC) Score to predict blood transfusions and the need for emergent laparotomy.

METHODS

Post hoc analysis of a prospective observational study of trauma patients who underwent an in-flight FAST during aeromedical transport during a 7-month period. PhABC Score was positive if ≥2 of the following were present in flight: penetrating trauma, heart rate >120 bpm, systolic blood pressure <90 mm Hg, or a positive abdominal FAST. The PhABC Score was evaluated by area under the receiver operating characteristic (AUROC) curves and logistic regression.

RESULTS

A total of 291 trauma patients met inclusion criteria, 23 underwent emergent laparotomy, and 12 received an MT. A positive PhABC Score predicted emergent laparotomy, with a positive predictive value of 48% and a negative predictive value of 95% (sensitivity 46%, specificity 96%, AUROC curve 0.83). A positive PhABC Score also predicted receipt of an MT with a positive predictive value of 28% and a negative predictive value of 94% (sensitivity 33%, specificity 93%, AUROC curve 0.77). Multiple logistic regression identified FAST as the most powerful contributor of the PhABC Score to the prediction of both emergent laparotomy (odds ratio 8.5, P < 0.001) and MT (odds ratio 5.9, P < 0.001).

CONCLUSIONS

The PhABC Score effectively predicts in-hospital resource utilization. It provides an outstanding undertriage rate from the prehospital setting, and it is helpful to improve trauma team activation, mobilize blood products, and prepare the operating room.

Characteristics of Nontrauma Patients Receiving Prehospital Blood Transfusion with the Same Triggers as Trauma Patients: A Retrospective Observational Cohort Study

Objective: While prehospital blood transfusion (PHBT) for trauma patients has been established in many services, the literature on PHBT use for nontrauma patients is limited. We aimed to describe and compare nontrauma and trauma patients receiving PHBT who had similar hemodynamic triggers. Methods: We analyzed 3.5 years of registry data from a single prehospital critical care unit. The PHBT protocol included two packed red blood cell units and was later completed with two freeze-dried plasma units. The transfusion triggers were a strong clinical suspicion of massive hemorrhage and systolic blood pressure below 90 mmHg or absent radial pulse. Results: Thirty-six nontrauma patients and 96 trauma patients received PHBT. The nontrauma group had elderly patients (median 65 [interquartile range, IQR, 56-73] vs 37 [IQR 25-57] years, p < 0.0001) and included patients with gastrointestinal bleeding (n = 15; 42%), vascular catastrophes (n = 9; 25%), postoperative bleeding (n = 6; 17%), obstetrical bleeding (n = 4; 11%) and other (n = 2; 6%). Cardiac arrest occurred in nine (25%) nontrauma and in 15 (16%) trauma patients. Of these, 5 (56%) and 10 (67%) survived to hospital admission and 3 (33%) and 2 (13%) to hospital discharge. On admission, the nontrauma patients had lower hemoglobin (median 95 [84-119] vs 124 [108-133], p < 0.0001), higher pH (median 7.40 [7.27-7.44] vs 7.30 [7.19-7.36], p = 0.0015) and lower plasma thromboplastin time (median 55 [45-81] vs 72 [58-86], p = 0.0261) than the trauma patients. Conclusions: We identified four nontrauma patient groups in need of PHBT, and the patients appeared to be seriously ill. Efficacy of prehospital transfusion in nontrauma patients should be evaluated futher in becoming studies.

Out-of-hospital Circulatory Measures to Identify Patients With Serious Injury: A Systematic Review

OBJECTIVE

The objective was to systematically identify and summarize out-of-hospital measures of circulatory compromise as diagnostic predictors of serious injury, focusing on measures usable by emergency medical services to inform field triage decisions.

METHODS

We searched Ovid MEDLINE, CINAHL, and the Cochrane databases from 1996 through August 2017 for published literature on individual circulatory measures in trauma. We reviewed reference lists of included articles for additional relevant citations. Measures of diagnostic accuracy included sensitivity, specificity, and area under the receiver operating characteristic curve (AUROC). Indicators of serious injury included resource need, serious anatomic injury, and mortality. We pooled estimates when data permitted.

RESULTS

We identified 114 articles, reporting results of 111 studies. Measures included systolic blood pressure (sBP), heart rate (HR), shock index (SI), lactate, base deficit, and HR variability. Pooled out-of-hospital sensitivity estimates were sBP < 90 mm Hg = 19% (95% confidence interval [CI] = 12% to 29%), HR ≥ 110 beats/min = 28% (95% CI = 20% to 37%), SI > 0.9 = 37% (95% CI = 22% to 56%), and lactate > 2.0 mmol/L = 74% (95% CI = 48% to 90%). Pooled specificity estimates were sBP < 90 mm Hg = 95% (95% CI = 91% to 97%), HR ≥ 110 beats/min = 85% (95% CI = 74% to 91%), SI > 0.9 = 85% (95% CI = 72% to 92%), and lactate > 2.0 mmol/L = 62% (95% CI = 51% to 72%). Pooled AUROCs included sBP = 0.67 (95% CI = 0.58 to 0.75), HR = 0.67 (95% CI = 0.56 to 0.79), SI = 0.72 (95% CI = 0.66 to 0.77), and lactate = 0.77 (95% CI = 0.67 to 0.82). Strength of evidence was low to moderate.

CONCLUSIONS

Out-of-hospital circulatory measures are associated with poor to fair discrimination for identifying trauma patients with serious injuries. Many seriously injured patients have normal circulatory measures (low sensitivity), but when present, the measures are highly specific for identifying patients with serious injuries.

Lactate levels and clearance rate in neonates undergoing mechanical ventilation in Tibet

Objective

This study aimed to examine the characteristics of blood lactate in neonates undergoing mechanical ventilation in Tibet.

Methods

We recruited 67 neonates undergoing mechanical ventilation in Naqu People’s Hospital as the plateau observation group and 94 neonates undergoing mechanical ventilation in Shengjing Hospital as the control group. We analyzed the differences in lactate levels between the two groups.

Results

The lactate clearance rates of neonates with asphyxia and those with respiratory distress syndrome were significantly lower in the plateau group than in the control group. Lactate levels in neonates who died in the plateau group were significantly higher and the lactate clearance rate was significantly lower than those in neonates who survived. The cut-off point for the lactate clearance rate at 6 hours for predicting mortality was 6.09% in the plateau group.

Conclusion

The lactate clearance rate of neonates on mechanical ventilation in the plateau area is lower than that in neonates in the non-plateau area. The lactate clearance rate at 6 hours is important for evaluating the prognoses of critical neonates in plateau areas.

Validation of a point-of-care capillary lactate measuring device (Lactate Pro 2)

Background

The measurement of lactate in emergency medical services has the potential for earlier detection of shock and can be performed with a point-of-care handheld device. Validation of a point-of-care handheld device is required for prehospital implementation.

Aim

The primary aim was to validate the accuracy of Lactate Pro 2 in healthy volunteers and in haemodynamically compromised intensive care patients. The secondary aim was to evaluate which sample site, fingertip or earlobe, is most accurate compared to arterial lactate.

Methods

Arterial, venous and capillary blood samples from fingertips and earlobes were collected from intensive care patients and healthy volunteers. Arterial and venous blood lactate samples were analysed on a stationary hospital blood gas analyser (ABL800 Flex) as the reference device and compared to the Lactate Pro 2. We used the Bland-Altman method to calculate the limits of agreement and used mixed effect models to compare instruments and sample sites. A total of 49 intensive care patients with elevated lactate and 11 healthy volunteers with elevated lactate were included.

Results

There was no significant difference in measured lactate between Lactate Pro 2 and the reference method using arterial blood in either the healthy volunteers or the intensive care patients. Capillary lactate measurement in the fingertip and earlobe of intensive care patients was 47% (95% CI (29 to 68%), p < 0.001) and 27% (95% CI (11 to 45%), p < 0.001) higher, respectively, than the corresponding arterial blood lactate. In the healthy volunteers, we found that capillary blood lactate in the fingertip was 14% higher than arterial blood lactate (95% CI (4 to 24%), p = 0.003) and no significant difference between capillary blood lactate in the earlobe and arterial blood lactate.

Conclusion

Our results showed that the handheld Lactate Pro 2 had good agreement with the reference method using arterial blood in both intensive care patients and healthy volunteers. However, we found that the agreement was poorer using venous blood in both groups. Furthermore, the earlobe may be a better sample site than the fingertip in intensive care patients.

Determinants of prehospital lactate in trauma patients: a retrospective cohort study

Background

Point of care serum lactate measurement is emerging as an adjunct to prehospital clinical assessment and has the potential to guide triage and advanced treatment decision-making. In this study we aimed to assess which factors potentially affect prehospital lactate levels.

Methods

We performed a retrospective cohort study of all trauma patients attended by the Air Ambulance, Kent, Surrey & Sussex (AAKSS) between July 2017 and April 2018 in whom a pre-hospital lactate was measured. Lactate was measured before AAKSS treatments were commenced, but generally after prehospital treatment by ground ambulance crews was initiated. Primary endpoint of interest was the association of various patient- and treatment characteristics with prehospital lactate levels.

Results

During the study period, lactate was measured in 156 trauma patients. Median lactate was 3.0 [2.0–4.1] mmol/l. Patients with an elevated lactate more often had deranged indices of end organ perfusion- and oxygenation (shock index 0.80 [0.58–1.03] vs 0.61 [0.40–0.82], p < 0.001, SpO₂ 96 [89–100%] vs 98 [96–100%], p = 0.025). They more often suffered from head injuries (62% vs 41%, p = 0.008), and received less analgesia prior to arrival of the AAKSS team (51.6% vs 67.2%, p = 0.03). In multivariate analysis, indices of end organ perfusion- and oxygenation only explained 15% of the variation in lactate levels.

Conclusions

Prehospital lactate levels are not solely associated with indices of end organ perfusion- and oxygenation. Injury type, treatments given on scene and many other (unmeasured) factors likely play an important role as well. This should be taken into account when lactate is used in clinical algorithms to guide prehospital triage or treatment.

Diagnostic et Prise en Charge de l’Acidose Métabolique Recommandations formalisées d’experts communes Société de réanimation de langue française (SRLF) – Société française de médecine d’urgence (SFMU)

L’acidose métabolique est un trouble fréquemment rencontré en médecine d’urgence et en médecine intensive réanimation. La littérature s’étant enrichie de nouvelles données concernant la prise en charge de l’acidose métabolique, la Société de Réanimation de Langue Française (SRLF) et la Société Française de Médecine d’Urgence (SFMU) ont élaboré des recommandations formalisées d’experts selon la méthodologie GRADE. Les champs de la stratégie diagnostique, de l’orientation et de la prise en charge thérapeutique ont été traités et vingt-neuf recommandations ont été formulées : quatre recommandations fortes (Grade 1), dix recommandations faibles (Grade 2) et quinze avis d’experts. Toutes ont obtenu un accord fort. L’application des méthodes d’Henderson-Hasselbalch et de Stewart pour le diagnostic du mécanisme de l’acidose métabolique est discutée et un algorithme diagnostique est proposé. L’utilisation de la cétonémie et des lactatémies veineuse et capillaire est également traitée. L’intérêt du pH, de la lactatémie et de sa cinétique pour l’orientation des patients en pré-hospitalier et aux urgences est envisagé. Enfin, les modalités de l’insulinothérapie au cours de l’acidocétose diabétique, les indications de la perfusion de bicarbonate de sodium et de l’épuration extra-rénale ainsi que les modalités de la ventilation mécanique au cours des acidoses métaboliques sévères sont traitées dans la prise en charge thérapeutique.

Prehospital lactate improves prediction of the need for immediate interventions for hemorrhage after trauma

The blood lactate level is used to guide the management of trauma patients with circulatory disturbance. We hypothesized that blood lactate levels at the scene (Lac scene) could improve the prediction for immediate interventions for hemorrhage. We prospectively measured blood lactate levels and assessed retrospectively in 435 trauma patients both at the scene and on arrival at the emergency room (ER) of a level I trauma center. Primary outcome was immediate intervention for hemorrhage defined as surgical/radiological intervention and/or blood transfusion within 24 h. Physiological variables plus Lac scene significantly increased the predictive value for immediate intervention (area under the curve [AUC] 0.882, 95% confidence interval [CI] 0.839-0.925) compared to that using physiological variables only (AUC 0.837, 95% CI 0.787-0.887, P = 0.0073), replicated in the validation cohort (n = 85). There was no significant improvement in predicting value of physiological variables plus Lac scene for massive transfusion compared to physiological variables (AUC 0.903 vs 0.895, P = 0.32). The increased blood lactate level per minute from scene to ER was associated with increased probability for immediate intervention (P < 0.0001). Both adding Lac scene to physiological variables and the temporal elevation of blood lactate levels from scene to ER could improve the prediction of the immediate intervention.

Point-of-care blood analysis of hypotensive patients in the emergency department

OBJECTIVE

The aim of this study is to compare a point-of-care (POC) analysis, Enterprise POC (epoc), using the capillary blood obtained from skin puncture with conventional laboratory tests using arterial and venous blood in hypotensive patients.

METHODS

This study was conducted at the emergency department of a tertiary care hospital between June and November 2018. 231 hypotensive patients were enrolled. Three types of blood samples (capillary blood from skin puncture and arterial and venous blood from blood vessel puncture) were collected and analyzed. We compared a total of 13 parameters (pH, pCO2, pO2, HCO3-, Ca2+, lactate, Na+, K+, Cl-, glucose, Hb, Hct, and creatinine) between the POC analysis and reference analyzers by performing the equivalence test and Bland-Altman plot analysis.

RESULTS

In hypotensive patients, with the exception of two parameters (pCO2, pO2), the pH, HCO3-, Ca2+, lactate, Na+, K+, Cl-, glucose, Hb, Hct, and creatinine parameters measured by the POC analysis were equivalent to or correlated with the reference values. In the patients with cardiac arrest group, nine parameters (pH, HCO3-, Ca2+, Na+, K+, glucose, Hb, Hct, and creatinine) analyzed by the epoc system were equivalent to the reference values.

CONCLUSION

Most parameters, except pO2, measured by the epoc system using the capillary blood in hypotensive patients were equivalent to or correlated with those measured by the reference analyzers.

Diagnosis and management of metabolic acidosis: guidelines from a French expert panel

Metabolic acidosis is a disorder frequently encountered in emergency medicine and intensive care medicine. As literature has been enriched with new data concerning the management of metabolic acidosis, the French Intensive Care Society (Société de Réanimation de Langue Française [SRLF]) and the French Emergency Medicine Society (Société Française de Médecine d’Urgence [SFMU]) have developed formalized recommendations from experts using the GRADE methodology. The fields of diagnostic strategy, patient assessment, and referral and therapeutic management were addressed and 29 recommendations were made: 4 recommendations were strong (Grade 1), 10 were weak (Grade 2), and 15 were experts’ opinions. A strong agreement from voting participants was obtained for all recommendations. The application of Henderson–Hasselbalch and Stewart methods for the diagnosis of the metabolic acidosis mechanism is discussed and a diagnostic algorithm is proposed. The use of ketosis and venous and capillary lactatemia is also treated. The value of pH, lactatemia, and its kinetics for the referral of patients in pre-hospital and emergency departments is considered. Finally, the modalities of insulin therapy during diabetic ketoacidosis, the indications for sodium bicarbonate infusion and extra-renal purification as well as the modalities of mechanical ventilation during severe metabolic acidosis are addressed in therapeutic management.

Handheld Tissue Oximetry for the Prehospital Detection of Shock and Need for Lifesaving Interventions: Technology in Search of an Indication?

Improved prehospital methods for assessing the need for lifesaving interventions (LSIs) are needed to gain critical lead time in the care of the injured. We hypothesized that threshold values using prehospital handheld tissue oximetry would detect occult shock and predict LSI requirements. This was a prospective observational study of adult trauma patients emergently transported by helicopter. Patients were monitored with a handheld tissue oximeter (InSpectra Spot Check; Hutchinson Technology Inc, Hutchinson, MN), continuous vital signs, and 21 laboratory measurements obtained both in the field with a portable analyzer and at the time of admission. Shock was defined as base excess ≥ 4 or lactate > 3 mmol/L. Eighty-eight patients were enrolled with a median Injury Severity Score of 16 (interquartile range, 5-29). The median hemoglobin saturation in the capillaries, venules, and arterioles (StO₂) value for all patients was 82% (interquartile range, 76%-87%; range, 42%-98%). StO₂ was abnormal (< 75%) in 18 patients (20%). Eight were hypotensive (9%) and had laboratory-confirmed evidence of occult shock. StO₂ correlated poorly with shock threshold laboratory values (r = -0.17; 95% confidence interval, -0.33 to 1.0; P = .94). The area under the receiver operating curve was 0.51 (95% confidence interval, 0.39-0.63) for StO₂ < 75% and laboratory-confirmed shock. StO₂ was not associated with LSI need on admission when adjusted for multiple covariates, nor was it independently associated with death. Handheld tissue oximetry was not sensitive or specific for identifying patients with prehospital occult shock. These results do not support prehospital StO₂ monitoring despite its inclusion in several published guidelines.

Is prehospital lactate testing useful in improving clinical assessment?

Introduction:

Lactate devices offer the potential for paramedics to improve patient triage and escalation of care for specific presentations. There is also scope to improve existing prehospital tools by including lactate measurement.

Method:

A literature search was conducted using the Medline, CINAHL, Academic Search Premier, Sciencedirect and Scopus databases.

Findings:

Acquiring prehospital lactate measurement in trauma settings improved triage and recognition of the need for critical care. Within a medical setting, studies offered mixed results in relating prehospital lactate measurement to diagnosis, escalating treatments and mortality. The accuracy of prehospital lactate measurements acquired varies, which could impact decision making.

Conclusion:

Prehospital lactate thresholds could aid decision making, although the literature is limited and evidence varies. Lactate values of ≥4 mmol/litre in medical and ≥2.5 mmol/litre in trauma patients could signify that care should be escalated to an appropriate facility, and that resuscitative measures should be initiated, particularly with sepsis, as reflected by standardised lactate values that guide treatment in hospitals. Similarly, a lactate value of <2 mmol/litre could mean de-escalating care into the community, although further research is warranted on this.

Diagnostic value of prehospital arterial blood gas measurements - a randomised controlled trial

Background

Arterial blood gas analysis is an important diagnostic tool in managing critically ill patients within the hospital. Whether prehospital application of this diagnostic modality contributes to more exact diagnoses and treatments in critically ill prehospital patients is unknown. The aim of this study was to establish whether access to arterial blood gas analysis increased the prehospital diagnostic accuracy of prehospital anaesthesiologists. Furthermore, we investigated whether prehospital blood gas analysis resulted in therapeutic interventions that would not have been carried out if the arterial blood gas analyser had not been available.

Methods

In a prospective randomised study, two groups of prehospital adult patients with acute critical illness were compared. All patients received standard prehospital care. In the intervention group, an arterial blood gas sample was analysed prehospitally. The primary outcome was the impact of blood gas analysis on the accuracy of prehospital diagnoses. Furthermore, we registered any therapeutic interventions that were carried out as a direct result of the blood gas analysis.

Results

A total of 310 patients were included in the study. Eighty-eight of these patients were subsequently excluded, primarily due to difficulties in obtaining post hoc consent or venous sampling or other technical difficulties. A total of 102 patients was analysed in the arterial blood gas group (ABG group), while 120 patients were analysed in the standard care group (noABG group). In 78 of the 102 patients in the ABG group, the prehospital physician reported that ABG analysis increased their perceived diagnostic precision. In 81 cases in the noABG group, the lack of arterial blood gas analysis was perceived to have decreased diagnostic accuracy. The claim that ABG analysis increased diagnostic accuracy could, however, not be substantiated as there was no difference in the number of un-specific diagnoses between the groups.

Blood gas analysis increased the probability of targeting specific prehospital therapeutic interventions and led to 159 interventions, including intubation, ventilation and/or upgrading the level of urgency, in 71 ABG-group patients (p < 0.001).

Conclusion

Although prehospital arterial blood gas analysis did not improve the accuracy of the prehospital diagnoses assigned to patients, it significantly increased the quality of treatment provided to patients with acute critical illness.

Trial registration

ClinicalTrials.gov, NCT03006692, retrospectively registered six months after first patient entry.

A retrospective analysis of the respiratory adjusted shock index to determine the presence of occult shock in trauma patients

BACKGROUND

The shock index (SI), calculated as hear rate/systolic blood pressure, is a simple hemodynamic marker that may be used to assess for the presence of occult shock in trauma patients. The normal range for a healthy adult patient is 0.5 to 0.7. Recently, studies have demonstrated that tachypnea is the most important predictor of cardiac arrest in hospital wards and is an important indicator of derangements across multiple organ systems. As such, we have sought to determine whether the inclusion of the patient's respiratory rate (RR) to the already existing SI (called the Respiratory Adjusted Shock Index [RASI]), calculated as hear rate/systolic blood pressure*(RR/10), will improve the overall diagnostic accuracy of detecting patients in early occult shock.

METHODS

A retrospective chart review over a 4-year period (2012-2016) at an urban, Level I trauma center was performed. All patients admitted to hospital for trauma were included in the study. Exclusion criteria were patients in traumatic arrest or in overt shock. Charts were reviewed for triage vital signs and point of care lactate drawn within 30 minutes of presentation. A lactate greater than 2 mmol/L was used to determine presence of hypoperfusion. The upper limit of normal for the RASI was calculated by multiplying the upper limit of the SI by 1.9 (RR of 19 divided by 10) and validated internally.

RESULTS

A total of 3,093 patients were included in this study. There was no difference in SI for patients discharged versus patients admitted, 0.6 (95% CI, 0.5-0.7) versus 0.7 (95% CI, 0.5-0.8) and a significant difference between the same groups of patients (discharged vs. admitted) for the RASI, 1.1 (95% CI, 1.04-1.18) versus 1.46 (95% CI, 1.35-1.55), respectively. Area under the curve for SI was 0.58 and for the RASI score was 0.94.

CONCLUSION

The RASI score improves diagnostic accuracy for detecting early occult shock in trauma patients when compared to the SI.

LEVEL OF EVIDENCE

Diagnostic, level II.

Compensatory Reserve Index: Performance of A Novel Monitoring Technology to Identify the Bleeding Trauma Patient

INTRODUCTION

Hemorrhage is one of the most substantial causes of death after traumatic injury. Standard measures, including systolic blood pressure (SBP), are poor surrogate indicators of physiologic compromise until compensatory mechanisms have been overwhelmed. Compensatory Reserve Index (CRI) is a novel monitoring technology with the ability to assess physiologic reserve. We hypothesized CRI would be a better predictor of physiologic compromise secondary to hemorrhage than traditional vital signs.

METHODS

A prospective observational study of 89 subjects meeting trauma center activation criteria at a single level I trauma center was conducted from October 2015 to February 2016. Data collected included demographics, SBP, heart rate, and requirement for hemorrhage-associated, life-saving intervention (LSI) (i.e., operation or angiography for hemorrhage, local or tourniquet control of external bleeding, and transfusion >2 units PRBC). Receiver-operator characteristic (ROC) curves were formulated and appropriate thresholds were calculated to compare relative value of the metrics for predictive modeling.

RESULTS

For predicting hemorrhage-related LSI, CRI demonstrated a sensitivity of 83% and a negative predictive value (NPV) of 91% as compared with SBP with a sensitivity to detect hemorrhage of 26% (P < 0.05) and an NPV of 78%. ROC curves generated from admission CRI and SBP measures demonstrated values of 0.83 and 0.62, respectively. CRI identified significant hemorrhage requiring potentially life-saving therapy more reliably than SBP (P < 0.05).

CONCLUSION

The CRI device demonstrated superior capacity over systolic blood pressure in predicting the need for posttraumatic hemorrhage intervention in the acute resuscitation phase after injury.

Early Lactate Dynamics in Critically Ill Non-Traumatic Patients in a Resuscitation Room of a German Emergency Department (OBSERvE-Lactate-Study)

BACKGROUND

Management of critically ill non-trauma patients in the resuscitation room of an emergency department (ED) is very challenging, and it is difficult to identify patients with a higher risk of death. Previous studies have shown that lactate indices can predict survival for selected diseases and syndromes.

OBJECTIVE

As reported for other patient populations, we set out to determine whether admission lactate or lactate dynamics (LD) within 24 h can predict 30-day mortality in unselected critically ill non-traumatic patients.

METHODS

In this retrospective study over a 1-year period, admission lactate, time weighted average lactate (Lac_TW) and LD of all critically ill adult patients admitted from ED to intensive care unit were analyzed. A linear regression model was implemented to estimate lactate data 1 h after admission.

RESULTS

The admission lactate, Lac_TW, and LD within 24 h were analyzed from 392 critically ill patients. The overall 30-day mortality rate was around 29%. Admission lactate (4.1 ± 4.0 mmol/L vs. 6.6 ± 6.1 mmol/L; p < 0.01) and Lac_TW (1.8 ± 1.7 mmol/L vs. 4.1 ± 4.8 mmol/L; p < 0.01) were different between survivors and non-survivors. LD between survivors and non-survivors did not differ at 1 h, 6 h, 12 h, or 24 h. After excluding patients with out-of-hospital or in-hospital cardiac arrest during resuscitation room management, admission lactate and LD between survivors and non-survivors did not differ at 1 h, 12 h, and 24 h. LD at 6 h (44% ± 42% vs. 33% ± 58%; p = 0.042) and Lac_TW (1.7 ± 1.6 mmol/L vs. 2.6 ± 3.0 mmol/L; p < 0.01) did differ.

CONCLUSIONS

In critically ill ED patients initially requiring treatment in a resuscitation room setting, LD at 6 h and Lac_TW may predict their survival beyond 30 days. These findings need to be confirmed in a prospective study design.

Prehospital Lactate Predicts Need for Resuscitative Care in Non-hypotensive Trauma Patients

Introduction

The prehospital decision of whether to triage a patient to a trauma center can be difficult. Traditional decision rules are based heavily on vital sign abnormalities, which are insensitive in predicting severe injury. Prehospital lactate (PLac) measurement could better inform the triage decision. PLac’s predictive value has previously been demonstrated in hypotensive trauma patients but not in a broader population of normotensive trauma patients transported by an advanced life support (ALS) unit.

Methods

This was a secondary analysis from a prospective cohort study of all trauma patients transported by ALS units over a 14-month period. We included patients who received intravenous access and were transported to a Level I trauma center. Patients with a prehospital systolic blood pressure ≤ 100 mmHg were excluded. We measured PLac’s ability to predict the need for resuscitative care (RC) and compared it to that of the shock index (SI). The need for RC was defined as either death in the emergency department (ED), disposition to surgical intervention within six hours of ED arrival, or receipt of five units of blood within six hours. We calculated the risk associated with categories of PLac.

Results

Among 314 normotensive trauma patients, the area under the receiver operator characteristic curve for PLac predicting need for RC was 0.716, which did not differ from that for SI (0.631) (p=0.125). PLac ≥ 2.5 mmol/L had a sensitivity of 74.6% and a specificity of 53.4%. The odds ratio for need for RC associated with a 1-mmol/L increase in PLac was 1.29 (95% confidence interval [CI] [0.40 – 4.12]) for PLac < 2.5 mmol/L; 2.27 (1.10 – 4.68) for PLac from 2.5 to 4.0 mmol/L; and 1.26 (1.05 – 1.50) for PLac ≥ 4 mmol/L.

Conclusion

PLac was predictive of need for RC among normotensive trauma patients. It was no more predictive than SI, but it has certain advantages and disadvantages compared to SI and could still be useful. Prospective validation of existing triage decision rules augmented by PLac should be investigated.

Emergency medical technician-performed point-of-care blood analysis using the capillary blood obtained from skin puncture

OBJECTIVE

Comparing a point-of-care (POC) test using the capillary blood obtained from skin puncture with conventional laboratory tests.

METHODS

In this study, which was conducted at the emergency department of a tertiary care hospital in April-July 2017, 232 patients were enrolled, and three types of blood samples (capillary blood from skin puncture, arterial and venous blood from blood vessel puncture) were simultaneously collected. Each blood sample was analyzed using a POC analyzer (epoc® system, USA), an arterial blood gas analyzer (pHOx®Ultra, Nova biomedical, USA) and venous blood analyzers (AU5800, DxH2401, Beckman Coulter, USA). Twelve parameters were compared between the epoc and reference analyzers, with an equivalence test, Bland-Altman plot analysis and linear regression employed to show the agreement or correlation between the two methods.

RESULTS

The pH, HCO₃, Ca²⁺, Na⁺, K⁺, Cl^-, glucose, Hb and Hct measured by the epoc were equivalent to the reference values (95% confidence interval of mean difference within the range of the agreement target) with clinically inconsequential mean differences and narrow limits of agreement. All of them, except pH, had clinically acceptable agreements between the two methods (results within target value ≥80%). Of the remaining three parameters (pCO_2, pO₂ and lactate), the epoc pCO₂ and lactate values were highly correlated with the reference device values, whereas pO₂ was not. (pCO₂: R²=0.824, y=-1.411+0.877·x; lactate: R²=0.902, y=-0.544+0.966·x; pO₂: R²=0.037, y=61.6+0.431·x).

CONCLUSION

Most parameters, except only pO₂, measured by the epoc were equivalent to or correlated with those from the reference method.

Prehospital Assessment of Trauma

The organization of prehospital care for trauma patients began in the military arena. At the urging of multiple stakeholders and providers, these lessons were applied to the civilian setting and emergency medical services were created across the nation. Advances have taken place in the triage, transport, and management of severely injured patients. Many issues remain in the care of trauma patients in the prehospital environment. Collaboration between stakeholders and providers, regionalization of trauma care, and protocol-driven care may be solutions to some of these issues. Further research is necessary to dictate standard of care in this early phase after injury.

Research questions in pre-hospital trauma care

Noting that a variety of pre-hospital interventions can now be applied to treat traumatic injury, David J Lockey calls for research to determine which of these actually improve survival and reduce morbidity.

Prehospital point-of-care lactate following trauma: A systematic review

BACKGROUND

Serum lactate serves as a surrogate marker for global tissue hypoxia following traumatic injury and has potential to guide resuscitation. Portable, handheld point-of-care monitoring devices enable lactate values to be readily available in the prehospital environment. The current review examines the utility of prehospital lactate (pLa) measurement in the management of trauma.

METHODS

MEDLINE and EMBASE databases were searched using predefined criteria (pLa measurement, trauma patients) until March 10, 2016. Studies were examined for lactate measurement as an intervention, prognostic indicator, and utilization in the guidance of goal-directed therapy. The Newcastle-Ottawa Scale was used to assess risk of bias, and quality of evidence was evaluated using the Grading of Recommendations, Assessment, Development, and Evaluation system. Data were unsuitable for meta-analysis and are presented in narrative form.

RESULTS

Of 2,415 articles of interest, seven met the inclusion criteria, all of which were observational studies, including 2,085 trauma patients. Lactate sampling techniques, timings, and thresholds were heterogeneous. No studies used pLa to guide intervention. Elevated pLa may be an independent prognostic marker of critical illness in trauma patients, particularly in blunt trauma. Prehospital lactate measurement may be more sensitive than systolic blood pressure in determining need for resuscitative care. Early lactate measurement may be particularly useful in the detection of occult hypoperfusion, with elevated pLa detectable within 30 minutes of injury. All current studies were assessed as being of "low" or "very low" quality and were at risk of bias. Considerable logistical barriers to pLa measurement exist.

CONCLUSIONS

Prehospital point-of-care lactate monitoring for trauma has been variably performed. There is a paucity of evidence relating to its use. The limited data available show feasibility and potential clinical utility, and further investigation is warranted to establish whether lactate might give meaningful guidance during prehospital triage and trauma patient resuscitation.

LEVEL OF EVIDENCE

Systematic review, level IV.

Muscle Oxygenation as an Early Predictor of Shock Severity in Trauma Patients

INTRODUCTION

We evaluated the potential utility of a new prototype noninvasive muscle oxygenation (MOx) measurement for the identification of shock severity in a population of patients admitted to the trauma resuscitation rooms of a Level I regional trauma center. The goal of this project was to correlate MOx with shock severity as defined by standard measures of shock: systolic blood pressure, heart rate, and lactate.

METHODS

Optical spectra were collected from subjects by placement of a custom-designed optical probe over the first dorsal interosseous muscles on the back of the hand. Spectra were acquired from trauma patients as soon as possible upon admission to the trauma resuscitation room. Patients with any injury were eligible for study. MOx was determined from the collected optical spectra with a multiwavelength analysis that used both visible and near-infrared regions of light. Shock severity was determined in each patient by a scoring system based on combined degrees of hypotension, tachycardia, and lactate. MOx values of patients in each shock severity group (mild, moderate, and severe) were compared using two-sample t tests.

RESULTS

In 17 healthy control patients, the mean MOx value was 91.0 ± 5.5%. A total of 69 trauma patients were studied. Patients classified as having mild shock had a mean MOx of 62.5 ± 26.2% (n = 33), those classified as in moderate shock had a mean MOx of 56.9 ± 26.9% (n = 25) and those classified as in severe shock had a MOx of 31.0 ± 17.1% (n = 11). Mean MOx for each of these groups was statistically different from the healthy control group (P < 0.05).Receiver operating characteristic analyses show that MOx and shock index (heart rate/systolic blood pressure) identified shock similarly well (area under the curves [AUC] = 0.857 and 0.828, respectively). However, MOx identified mild shock better than shock index in the same group of patients (AUC = 0.782 and 0.671, respectively).

CONCLUSIONS

The results obtained from this pilot study indicate that MOx correlates with shock severity in a population of trauma patients. Noninvasive and continuous MOx holds promise to aid in patient triage and to evaluate patient condition throughout the course of resuscitation.

Prehospital lactate improves accuracy of prehospital criteria for designating trauma activation level

BACKGROUND

Trauma activation level is determined by prehospital criteria. The American College of Surgeons (ACS) recommends trauma activation criteria; however, their accuracy may be limited. Prehospital lactate has shown promise in predicting trauma center resource requirements. Our objective was to investigate the added value of incorporating prehospital lactate in an algorithm to designate trauma activation level.

METHODS

Air medical trauma patients undergoing prehospital lactate measurement were included. Algorithms using ACS activation criteria (ACS) and ACS activation criteria plus prehospital lactate (ACS+LAC) to designate trauma activation level were compared. Test characteristics and net reclassification improvement (NRI), which evaluates reclassification of patients among risk categories with additional predictive variables, were calculated. Algorithms were compared to predict trauma center need defined as more than 1 unit of blood in the emergency department; spinal cord injury; advanced airway; thoracotomy or pericardiocentesis; ICP monitoring; emergent operative or interventional radiology procedure; or death.

RESULTS

There were 6,347 patients included. Twenty-eight percent had trauma center need. The ACS+LAC algorithm upgraded 256 patients and downgraded 548 patients compared to the ACS algorithm. The ACS+LAC algorithm versus ACS algorithm had an NRI of 0.058 (95% confidence interval [CI], 0.044-0.071; p < 0.01), with an event NRI of -0.5% and nonevent NRI of 6.2%. When weighted to favor changes in undertriage, the ACS+LAC still had a favorable overall reclassification (weighted NRI, 0.041; 95% CI, 0.028-0.054; p = 0.01). The ACS+LAC algorithm increased positive predictive value, negative predictive value, and accuracy. Over-triage was reduced 7.2%, while undertriage only increased 0.7%. The area under the curve was significantly higher for the ACS+LAC algorithm (0.79 vs. 0.76; p < 0.01).

CONCLUSIONS

The ACS+LAC algorithm reclassified patients to more appropriate levels of trauma activation compared to the ACS algorithm. This overall benefit is achieved by significant reduction in overtriage relative to very small increase in undertriage. In the context of trauma team activation, this trade-off may be acceptable, especially in the current health care environment.

LEVEL OF EVIDENCE

Therapeutic/care management study, level III; prognostic/epidemiologic study, level III.

"Blood failure" time to view blood as an organ: how oxygen debt contributes to blood failure and its implications for remote damage control resuscitation

Hemorrhagic shock is both a local and systemic disorder. In the context of systemic effects, blood loss may lead to levels of reduced oxygen delivery (DO2 ) sufficient to cause tissue ischemia. Similar to other physiologic debts such as sleep, it is not possible to incur a significant oxygen debt and suffer no consequences for lack of timely repayment. While the linkage between oxygen debt and traditional organ failure (renal, hepatic, lung, and circulation) has been long recognized, we should consider failure in two additional linked and very dynamic organ systems, the endothelium and blood. These systems are very sensitive to oxygen debt and at risk for failing, having further implications on all other organ systems. The degree of damage to the endothelium is largely modulated by the degree of oxygen debt. Thus hypoperfusion is believed to begin a cascade of events leading to acute traumatic coagulopathy (ATC). This combination of oxygen debt driven endothelial damage and ATC might be considered collectively as "blood failure" due to the highly connected networks between these drivers. This article presents the implications of oxygen debt for remote damage control resuscitation strategies, such as permissive hypotension and hemostatic resuscitation. We review the impact of whole blood resuscitation and red blood cell efficacy in mitigation of oxygen debt. At last, this article recognizes the need for simple and durable, lightweight equipment that can detect the adequacy of tissue DO2 and thus patient needs for resuscitative care. Point-of-care lactate measuring may be a predictive tool for identifying high-risk trauma patients and occult shock because it provides information beyond that of vital signs and mechanism of injury as it may help predict the level of oxygen debt accumulation and need for resuscitation. Serial measurements may also be valuable as a tool in guiding resuscitative efforts.

Utility of Measurement of Serum Lactate in Diagnosis of Coagulopathy Associated with Peripheral Circulatory Insufficiency: Retrospective Evaluation Using Thromboelastometry from a Single Center in Japan

Recently, serum lactate level rather than systolic blood pressure (sBP) has been widely used to diagnose peripheral circulatory insufficiency, which often leads to coagulopathy with systemic inflammation. However, most of the reported disorders were examined by plasma samples. The aim of this study was to evaluate the utility of serum lactate for detecting coagulopathy with circulatory failure by using thromboelastometry as well as standard coagulation test. 192 adult patients transported to our hospital between January 2013 and September 2014 were enrolled in this retrospective study. The sBP, serum lactate and thromboelastometry (ROTEM(®)) were measured in these patients in the emergency department. All patients were divided into three groups based on serum lactate levels: (1) the severe group (≥4 mmol/L, n=41); (2) the mild group (<4 mmol/L and ≥2 mmol/L, n=59); and (3) the normal group (<2 mmol/L, n=92). Patients in the severe group were of a significantly younger age but had lower pH and poor outcome. SBP was significantly lower and heart rates were higher in the severe group than in the other groups. Prolonged PT-INR and APTT were statistically confirmed in the severe group. ROTEM findings in the severe group revealed significantly lower alpha angle, shortened Lysis Onset Time and significantly more cases exhibited hyperfibrinolysis. The same analysis with the cut-off level of sBP at 90 mmHg showed no significant difference in ROTEM findings between the two groups. Abnormal serum lactate levels (≥4.0 mmol/L) properly reflected peripheral circulatory insufficiency and were more closely associated with coagulopathy such as hyperfibrinolysis and hypocoagulability than sBP.

Basic arterial blood gas biomarkers as a predictor of mortality in tetralogy of Fallot patients

Background:

Serum lactate and base deficit have been shown to be a predictor of morbidity and mortality in critically ill patients. Poor preoperative oxygenation appears to be one of the significant factors that affects early mortality in tetralogy of Fallot (TOF). There is little published literature evaluating the utility of serum lactate, base excess (BE), and oxygen partial pressure (PO₂) as simple, widely available, prognostic markers in patients undergoing surgical repair of TOF.

Materials and Methods:

This prospective, observational study was conducted in 150 TOF patients, undergoing elective intracardiac repair. PO₂, BE, and lactate levels at three different time intervals were recorded. Arterial blood samples were collected after induction (T1), after cardiopulmonary bypass (T2), and 48 h (T3) after surgery in the Intensive Care Unit (ICU). To observe the changes in PO₂, BE, and lactate levels over a period of time, repeated measures analysis was performed with Bonferroni method. The receiver operating characteristics (ROC) analysis was used to find area under curve (AUC) and cutoff values of various biomarkers for predicting mortality in ICU.

Results:

The patients who could not survive showed significant elevated lactate levels at baseline (T1) and postoperatively (T2) as compared to patients who survived after surgery (P < 0.001). However, in nonsurvivors, the BE value decreased significantly in the postoperative period in comparison to survivors (−2.8 ± 4.27 vs. 5.04 ± 2.06) (P < 0.001). In nonsurvivors, there was a significant fall of PO₂ to a mean value of 59.86 ± 15.09 in ICU (T3), whereas those who survived had a PO₂ of 125.86 ± 95.09 (P < 0.001). The ROC curve analysis showed that lactate levels (T3) have highest mortality predictive value (AUC: 96.9%) as compared to BE (AUC: 94.5%) and PO₂ (AUC: 81.1%).

Conclusion:

Serum lactate and BE may be used as prognostic markers to predict mortality in patients undergoing TOF repair. The routine analysis of these simple, fast, widely available, and cost-effective biomarkers should be encouraged to predict prognosis of TOF patients.

A Derivation and Validation Study of an Early Blood Transfusion Needs Score for Severe Trauma Patients

Background

There is no existing adequate blood transfusion needs determination tool that Emergency Medical Services (EMS) personnel can use for prehospital blood transfusion initiation. In this study, a simple and pragmatic prehospital blood transfusion needs scoring system was derived and validated.

Methods

Local trauma registry data were reviewed retrospectively from 2004 through 2013. Patients were randomly assigned to derivation and validation cohorts. Multivariate logistic regression was used to identify the independent approachable risks associated with early blood transfusion needs in the derivation cohort in which a scoring system was derived. Sensitivity, specificity, and area under the receiver operational characteristic (AUC) were calculated and compared using both the derivation and validation data.

Results

A total of 24,303 patients were included with 12,151 patients in the derivation and 12,152 patients in the validation cohorts. Age, penetrating injury, heart rate, systolic blood pressure, and Glasgow coma scale (GCS) were risks predictive of early blood transfusion needs. An early blood transfusion needs score was derived. A score > 5 indicated risk of early blood transfusion need with a sensitivity of 83% and a specificity of 80%. A sensitivity of 82% and a specificity of 80% were also found in the validation study and their AUC showed no statistically significant difference (AUC of the derivation = 0.87 versus AUC of the validation = 0.86, P > 0.05).

Conclusions

An early blood transfusion scoring system was derived and internally validated to predict severe trauma patients requiring blood transfusion during prehospital or initial emergency department resuscitation.

Implementation of the ABL-90 blood gas analyzer in a ground-based mobile emergency care unit

Point-of Care analysis is increasingly being applied in the prehospital scene. Arterial blood gas analysis is one of many new initiatives adding to the diagnostic tools of the prehospital physician. In this paper we present a study on the feasibility of the Radiometer ABL-90 in a ground-based Mobile Emergency Care Unit and report on some clinical situations in which the apparatus has proven beneficial.