Inefficacy of standard vital signs for predicting mortality and the need for prehospital life-saving interventions in blunt trauma patients transported via helicopter: A repeated call for new measures

Recovery to normal vital functions and acid-base status after a severe trauma in Level I versus Level II Trauma Centres

PURPOSE

In the Netherlands, approximately 70% of severely injured patients (ISS ≥ 16) are transported directly to a Level I trauma center. This study compared the time needed to return to normal vital parameters and normal acid-base status in severely injured patients and some in-hospital processes in Level I versus Level II trauma centers.

METHODS

This retrospective cohort study included all adult severely injured patients or adult trauma patients admitted to the intensive care unit between 2015 and 2020 in a Dutch trauma region. The primary endpoint was time until normal vital parameters and acid-base status. Secondary endpoints were complication rate, hospital length of stay, emergency department length of stay, and time until a computed tomography (CT) scan.

RESULTS

A total of 2345 patients were included. Patients admitted to a Level I trauma center had a significantly higher rate of normalization of vital parameters over time (HR 1.51). There was no significant difference in normalization rate of the acid-base status over time (HR 1.10). In Level I trauma centers, time spent at the emergency department and time until the CT scan was significantly shorter (respectively, β - 38 min and β - 77 min), and the complication rate was significantly lower (OR 0.35).

CONCLUSION

Severely injured patients admitted to a Level I trauma center require less time to normalize their vital functions. Level I centers are better equipped, resulting in better in-hospital processes with shorter time at the emergency department and shorter time until a CT scan.

Effectiveness of road safety interventions: An evidence and gap map

Background

Road Traffic injuries (RTI) are among the top ten leading causes of death in the world resulting in 1.35 million deaths every year, about 93% of which occur in low- and middle-income countries (LMICs). Despite several global resolutions to reduce traffic injuries, they have continued to grow in many countries. Many high-income countries have successfully reduced RTI by using a public health approach and implementing evidence-based interventions. As many LMICs develop their highway infrastructure, adopting a similar scientific approach towards road safety is crucial. The evidence also needs to be evaluated to assess external validity because measures that have worked in high-income countries may not translate equally well to other contexts. An evidence gap map for RTI is the first step towards understanding what evidence is available, from where, and the key gaps in knowledge.

Objectives

The objective of this evidence gap map (EGM) is to identify existing evidence from all effectiveness studies and systematic reviews related to road safety interventions. In addition, the EGM identifies gaps in evidence where new primary studies and systematic reviews could add value. This will help direct future research and discussions based on systematic evidence towards the approaches and interventions which are most effective in the road safety sector. This could enable the generation of evidence for informing policy at global, regional or national levels.

Search Methods

The EGM includes systematic reviews and impact evaluations assessing the effect of interventions for RTI reported in academic databases, organization websites, and grey literature sources. The studies were searched up to December 2019.

Selection Criteria

The interventions were divided into five broad categories: (a) human factors (e.g., enforcement or road user education), (b) road design, infrastructure and traffic control, (c) legal and institutional framework, (d) post-crash pre-hospital care, and (e) vehicle factors (except car design for occupant protection) and protective devices. Included studies reported two primary outcomes: fatal crashes and non-fatal injury crashes; and four intermediate outcomes: change in use of seat belts, change in use of helmets, change in speed, and change in alcohol/drug use. Studies were excluded if they did not report injury or fatality as one of the outcomes.

Data Collection and Analysis

The EGM is presented in the form of a matrix with two primary dimensions: interventions (rows) and outcomes (columns). Additional dimensions are country income groups, region, quality level for systematic reviews, type of study design used (e.g., case-control), type of road user studied (e.g., pedestrian, cyclists), age groups, and road type. The EGM is available online where the matrix of interventions and outcomes can be filtered by one or more dimensions. The webpage includes a bibliography of the selected studies and titles and abstracts available for preview. Quality appraisal for systematic reviews was conducted using a critical appraisal tool for systematic reviews, AMSTAR 2.

Main Results

The EGM identified 1859 studies of which 322 were systematic reviews, 7 were protocol studies and 1530 were impact evaluations. Some studies included more than one intervention, outcome, study method, or study region. The studies were distributed among intervention categories as: human factors (n = 771), road design, infrastructure and traffic control (n = 661), legal and institutional framework (n = 424), post-crash pre-hospital care (n = 118) and vehicle factors and protective devices (n = 111). Fatal crashes as outcomes were reported in 1414 records and non-fatal injury crashes in 1252 records. Among the four intermediate outcomes, speed was most commonly reported (n = 298) followed by alcohol (n = 206), use of seatbelts (n = 167), and use of helmets (n = 66). Ninety-six percent of the studies were reported from high-income countries (HIC), 4.5% from upper-middle-income countries, and only 1.4% from lower-middle and low-income countries. There were 25 systematic reviews of high quality, 4 of moderate quality, and 293 of low quality.

Authors' Conclusions

The EGM shows that the distribution of available road safety evidence is skewed across the world. A vast majority of the literature is from HICs. In contrast, only a small fraction of the literature reports on the many LMICs that are fast expanding their road infrastructure, experiencing rapid changes in traffic patterns, and witnessing growth in road injuries. This bias in literature explains why many interventions that are of high importance in the context of LMICs remain poorly studied. Besides, many interventions that have been tested only in HICs may not work equally effectively in LMICs. Another important finding was that a large majority of systematic reviews are of low quality. The scarcity of evidence on many important interventions and lack of good quality evidence-synthesis have significant implications for future road safety research and practice in LMICs. The EGM presented here will help identify priority areas for researchers, while directing practitioners and policy makers towards proven interventions.

Comparison of Changes in Vital Signs During Ground and Helicopter Emergency Medical Services and Hospital Interventions

OBJECTIVE

Few studies have evaluated the effects of helicopter emergency medical services (HEMS) alone. This single-center study compared the changes in vital signs during ground emergency medical services (GEMS), HEMS, and hospital interventions to assess the impact of HEMS interventions.

METHODS

This retrospective observational study included 168 trauma patients older than 18 years of age who received HEMS. Patients with cardiac arrest or those who received medical attention before HEMS were excluded. We assessed 3 intervention phases (GEMS, HEMS, and hospital). The changes in heart rate, systolic blood pressure, respiratory rate, and shock index in response to interventions were calculated and divided by the intervention time, and the changes observed during the interventions were compared.

RESULTS

No changes in vital signs were observed when receiving GEMS. Systolic blood pressure increased and shock index decreased after HEMS, whereas systolic blood pressure decreased and shock index increased during hospital interventions. Heart rate showed no significant change (P = .12), and respiratory rate showed very little change. Systolic blood pressure increased significantly during HEMS compared with the pre- and postintervention periods.

CONCLUSION

Changes in vital signs differed according to the intervention. Systolic blood pressure increased during HEMS but not with GEMS or hospital interventions.

Effects of experimental hypovolemia and pain on pre-ejection period and pulse transit time in healthy volunteers

Trauma patients may suffer significant blood loss, and noninvasive methods to diagnose hypovolemia in these patients are needed. Physiologic effects of hypovolemia, aiming to maintain blood pressure, are largely mediated by increased sympathetic nervous activity. Trauma patients may however experience pain, which also increases sympathetic nervous activity, potentially confounding measures of hypovolemia. Elucidating the common and separate effects of the two stimuli on diagnostic methods is therefore important. Lower body negative pressure (LBNP) and cold pressor test (CPT) are experimental models of central hypovolemia and pain, respectively. In the present analysis, we explored the effects of LBNP and CPT on pre‐ejection period and pulse transit time, aiming to further elucidate the potential use of these variables in diagnosing hypovolemia in trauma patients. We exposed healthy volunteers to four experimental sequences with hypovolemia (LBNP 60 mmHg) or normovolemia (LBNP 0 mmHg) and pain (CPT) or no pain (sham) in a 2 × 2 fashion. We calculated pre‐ejection period and pulse transit time from ECG and ascending aortic blood velocity (suprasternal Doppler) and continuous noninvasive arterial pressure waveform (volume‐clamp method). Fourteen subjects were available for the current analyses. This experimental study found that pre‐ejection period increased with hypovolemia and remained unaltered with pain. Pulse transit time was reduced by pain and increased with hypovolemia. Thus, the direction of change in pulse transit time has the potential to distinguish hypovolemia and pain.

Accuracy of prehospital clinicians' perceived prognostication of long-term survival in critically ill patients: a nationwide retrospective cohort study on helicopter emergency service patients

OBJECTIVES

Prehospital critical care physicians regularly attend to patients with poor prognosis and may limit the advanced therapies. The aim of this study was to evaluate the accuracy of poor prognosis given by prehospital critical care clinicians.

DESIGN

Cohort study.

SETTING

We performed a retrospective cohort study using the national helicopter emergency medical services (HEMS) quality database.

PARTICIPANTS

Patients classified by the HEMS clinician to have survived until hospital admission solely because of prehospital interventions but evaluated as having no long-term survival by prehospital clinician, were included.

PRIMARY AND SECONDARY OUTCOME

The survival of the study patients was examined at 30 days, 1 year and 3 years.

RESULTS

Of 36 715 patients encountered by the HEMS during the study period, 2053 patients were classified as having no long-term survival and included. At 30 days, 713 (35%, 95% CI 33% to 37%) were still alive and 69 were lost to follow-up. Furthermore, at 1 year 524 (26%) and at 3 years 267 (13%) of the patients were still alive. The deceased patients received more often prehospital rapid sequence intubation and vasoactives, compared with patients alive at 30 days. Patients deceased at 30 days were older and had lower initial Glasgow Coma Scores. Otherwise, no clinically relevant difference was found in the prehospital vital parameters between the survivors and non-survivors.

CONCLUSIONS

The prognostication of long-term survival for critically ill patients by a prehospital critical care clinician seems to fulfil only moderately. A prognosis based on clinical judgement must be handled with a great degree of caution and decision on limitation of advanced care should be made cautiously.

Vital and Clinical Signs Gathered Within the First Minutes After a Motorcycle Accident on a Racetrack: an Observational Study

Background

Little is known about vital signs during the very first minutes after an accident. This study aimed to describe the vital signs of motorcycle riders shortly after racetrack crashes and examine the clinical value of these data for the prehospital clinical assessments.

Methods

A retrospective observational cohort based on data from medical records on 104 motorcycle accidents at a racetrack in Sweden, covering the season of 2019 (May 01 until September 17), was conducted. Both race and practice runs were included. In addition, data from the Swedish Trauma Registry were used for patients referred to the hospital. Kruskal-Wallis test and linear regression were calculated in addition to descriptive statistics.

Results

In all, 30 riders (29%) were considered injured. Sixteen riders (15%) were referred to the hospital, and of these, five patients (5% of all riders) had suffered serious injuries. Aside from a decreased level of consciousness, no single vital sign or kinematic component observed within the early minutes after a crash was a strong clinical indicator of the occurrence of injuries. However, weak links were found between highsider or collision crashes and the occurrence of injuries.

Conclusion

Except for a decreased level of consciousness, this study indicates that the clinical value of early measured vital signs might be limited for the pre-hospital clinical assessment in the motorsport environment. Also, an adjustment of general trauma triage protocols might be considered for settings such as racetracks. Using the context with medical professionals at the victim’s side within a few minutes after an accident, that is common in motorsport, offers unique possibilities to increase our understanding of clinical signs and trauma in the early state after an accident.

Prehospital Variables Alone Can Predict Mortality After Blunt Trauma: A Novel Scoring Tool

BACKGROUND

We sought to develop a novel Prehospital Injury Mortality Score (PIMS) to predict blunt trauma mortality using only prehospital variables.

STUDY DESIGN

The 2017 Trauma Quality Improvement Program database was queried and divided into two equal sized sets at random (derivation and validation sets). Multiple logistic regression models were created to determine the risk of mortality using age, sex, mechanism, and trauma activation criterion. The PIMS was derived using the weighted average of each independent predictor. The discriminative power of the scoring tool was assessed by calculating the area under the receiver operating characteristics (AUROC) curve. The PIMS ability to predict mortality was then assessed by using the validation cohort. The score was compared to the Revised Trauma Score (RTS) using the AUROC curve, including a subgroup of patients with normal vital signs.

RESULTS

The derivation and validation groups each consisted of 163 694 patients. Seven independent predictors of mortality were identified, and the PIMS was derived with scores ranging from 0 to 20. The mortality rate increased from 1.4% to 43.9% and then 100% at scores of 1, 10, and 19, respectively. The model had very good discrimination with an AUROC of .79 in both the derivation and validation groups. When compared to the RTS, the AUROC were similar (.79 vs. .78). On subgroup analysis of patients with normal prehospital vital signs, the PIMS was superior to the RTS (.73 vs. .56).

CONCLUSION

The PIMS is a novel scoring tool to predict mortality in blunt trauma patients using prehospital variables. It had improved discriminatory power in blunt trauma patients with normal vital signs compared to the RTS.

Prehospital shock index outperforms hypotension alone in predicting significant injury in trauma patients

BACKGROUND

The American College of Surgeons Resources for Optimal Care of the Injured Patient recommends using hypotension, defined as systolic blood pressure ≤90 mm Hg, as an indicator of a full team trauma activation. We hypothesized that an elevated shock index (SI) predicts significant traumatic injuries better than hypotension alone.

METHODS

This is a retrospective cohort study analyzing full team trauma activations between February 2018 and January 2020, excluding transfers and those who had missing values for prehospital blood pressure or heart rate. We reviewed patients' demographics, prehospital and emergency department vitals, injury pattern, need for operation, and clinical outcomes. The primary outcome was rate of significant injury defined as identified injured liver, spleen, or kidney, pelvis fracture, long bone fracture, significant extremity soft tissue damage, hemothorax, or pneumothorax.

RESULTS

Among 544 patients, 82 (15.1%) had prehospital hypotension and 492 had normal blood pressure. Of the patients with prehospital hypotension, 34 (41.5%) had a significant injury. There was no difference in age, gender, medical history, or injury pattern between the two groups. There was no difference between the two groups in rate of serious injury (41.5% vs. 46.1%, NS), need for emergent operation (31.7% vs. 28.1%, NS) or death (20.7% vs. 18.8%, NS). On the other hand, SI ≥1 was associated with increased rate of serious injury (54.6% vs. 43.4%, p=0.04). On a logistic regression analysis, prehospital hypotension was not associated with significant injury or need for emergent operation (OR 0.83, 95% CI 0.51 to 1.33 and OR 1.32, 95% CI 0.79 to 2.25, respectively). SI ≥1 was associated with both increased odds of significant injury and need for emergent operation (OR 1.57, 95% CI 1.01 to 2.44 and OR 1.64, 95% CI 1.01 to 2.66).

DISCUSSION

SI was a better indicator and could replace hypotension to better categorize and triage patients in need of higher level of care.

LEVEL OF EVIDENCE

Prognostic and epidemiologic, level III.

Physiology of Human Hemorrhage and Compensation

Hemorrhage is a leading cause of death following traumatic injuries in the United States. Much of the previous work in assessing the physiology and pathophysiology underlying blood loss has focused on descriptive measures of hemodynamic responses such as blood pressure, cardiac output, stroke volume, heart rate, and vascular resistance as indicators of changes in organ perfusion. More recent work has shifted the focus toward understanding mechanisms of compensation for reduced systemic delivery and cellular utilization of oxygen as a more comprehensive approach to understanding the complex physiologic changes that occur following and during blood loss. In this article, we begin with applying dimensional analysis for comparison of animal models, and progress to descriptions of various physiological consequences of hemorrhage. We then introduce the complementary side of compensation by detailing the complexity and integration of various compensatory mechanisms that are activated from the initiation of hemorrhage and serve to maintain adequate vital organ perfusion and hemodynamic stability in the scenario of reduced systemic delivery of oxygen until the onset of hemodynamic decompensation. New data are introduced that challenge legacy concepts related to mechanisms that underlie baroreflex functions and provide novel insights into the measurement of the integrated response of compensation to central hypovolemia known as the compensatory reserve. The impact of demographic and environmental factors on tolerance to hemorrhage is also reviewed. Finally, we describe how understanding the physiology of compensation can be translated to applications for early assessment of the clinical status and accurate triage of hypovolemic and hypotensive patients. © 2021 American Physiological Society. Compr Physiol 11:1531-1574, 2021.

Association of Prehospital Step 1 Vital Sign Criteria and Vital Sign Decline with Increased Emergency Department and Hospital Death

BACKGROUND

This study analyzed data from the 2017 American College of Surgeons National Trauma Data Bank to examine the effects of pre-hospital Field Triage Decision Scheme Step 1 vital sign criteria (S1C) and vital sign decline on subsequent emergency department (ED) and hospital death in emergency medical services (EMS) transported trauma victims.

STUDY DESIGN

Patient and injury characteristics, transport time, and ED and hospital disposition were collected. S1C (respiratory rate [RR]<10, RR>29 breaths/min, systolic blood pressure [SBP]<90 mmHg, Glasgow Coma Scale [GCS]<14) were recorded at the injury scene and hospital arrival. Decline was defined as a change ≥ 1 standard deviation (SD) into or within an S1C range. S1C and decline were analyzed relative to ED and hospital death using logistic regression.

RESULTS

Of 333,213 included patients, 54,849 (16.5%) met Step 1 criteria at the scene, and 21,566 (6.9%) declined en route. The ED death rate was 0.4% (n = 1,188), and the hospital death/hospice rate was 4.0% (11,624 of 287,675). Patients who met S1C at the scene or who declined were more likely to require longer hospital lengths of stay, ICU admission, and surgical intervention. S1C and decline patients had higher odds of death in both the ED (S1C odds ratio [OR] 15.1, decline OR 2.4, p values < 0.001) and hospital (S1C OR 4.8, decline OR 2.0, p values < 0.001) after adjusting for patient demographics, transport time and mode, injury severity, and injury mechanism. Each S1C and decline measure was independently predictive of death.

CONCLUSIONS

This study quantifies the mortality risks associated with individual S1C and validates their use as an indicator for injury severity and pre-hospital triage tool.

Agreement between arterial and venous blood gases in trauma resuscitation in emergency department (AGREE)

INTRODUCTION

Arterial blood gas (ABG) sampling is routinely performed in major trauma patients to assess the severity of hemorrhagic shock. Compared to venous blood gas (VBG), ABG is an additional procedure with risks of hematoma and pain. We aim to determine if pH, base deficit (BD), and lactate from VBG and ABG in trauma patients are clinically equivalent. If proven, the need for ABG and its associated risks can be eliminated.

METHODS

This prospective observational study was conducted in the Emergency Department of National University Hospital, Singapore, between February and October 2016. We correlated paired ABG and VBG results in adult trauma patients. VBG and ABG were obtained within 10 min and processed within 5 min using a point-of-care blood gas analyzer. Bland-Altman plot analysis was used to evaluate the agreement between peripheral VBG and ABG in terms of pH, base deficit and lactate.

RESULTS

There were 102 patients included, with a median age of 34 (interquartile range 28-46) years and male predominance (90.2%). Majority of patients sustained blunt trauma (96.1%), and had injuries of Tier 1 and Tier 2 severity (60/102, 58.8%). Bland-Altman plot analyses demonstrated that only 72.6% of venous pH and 76.5% of venous BD lie within the pre-defined clinically acceptable limits of agreement, whereas 96.0% of venous lactate was within these limits.

CONCLUSION

Venous and arterial pH and BD are not within clinically acceptable limits of agreement, and ABG should be obtained for accurate acid-base status. However, venous lactate may be an acceptable substitute for arterial lactate.

Prehospital quick sequential organ failure assessment as a tool to predict in-hospital mortality

OBJECTIVE

This study aimed to evaluate the predictive ability of quick sequential organ failure assessment (qSOFA) score for in-hospital mortality among patients transported by physician-staffed helicopters.

METHODS

We conducted a single-center, retrospective observational study using the physician-staffed helicopter registry data between 2003 and 2016. We calculated the qSOFA scores based on the patients' vital signs, which were measured on the scene. The tool's discriminatory ability was determined using the area under the curve of the receiver operating characteristic.

RESULTS

A total of 1849 patients with a mean age of 63.0 (standard deviation [SD], 18.4) years were included in this study. The diagnostic categories included were trauma and nontrauma cases (1038 [56%] and 811 [44%], respectively). In-hospital mortality was documented in 169 (9%) patients. Meanwhile, the in-hospital mortality rates among patients with qSOFA scores of 0, 1, 2, and 3 were 5/411 (1%), 69/797 (9%), 71/541 (13%), and 24/100 (24%), respectively (P<0.0001 for trend). If the cutoff point is ≥1, the sensitivity and specificity of the qSOFA scores were 0.97 and 0.24, respectively. The area under the curve of the qSOFA scores was 0.67 for all patients, whereas that for trauma patients was 0.75.

CONCLUSION

An increase in the qSOFA score is associated with a gradual increase in the in-hospital mortality rate among all patients. In particular, a very low mortality rate was observed among patients with a qSOFA score of 0. The qSOFA score predicted the in-hospital mortality of patients with trauma well.