Permissive hypotension for active haemorrhage in trauma

Modern Learning from Big Data in Critical Care: Primum Non Nocere

Large and complex data sets are increasingly available for research in critical care. To analyze these data, researchers use techniques commonly referred to as statistical learning or machine learning (ML). The latter is known for large successes in the field of diagnostics, for example, by identification of radiological anomalies. In other research areas, such as clustering and prediction studies, there is more discussion regarding the benefit and efficiency of ML techniques compared with statistical learning. In this viewpoint, we aim to explain commonly used statistical learning and ML techniques and provide guidance for responsible use in the case of clustering and prediction questions in critical care. Clustering studies have been increasingly popular in critical care research, aiming to inform how patients can be characterized, classified, or treated differently. An important challenge for clustering studies is to ensure and assess generalizability. This limits the application of findings in these studies toward individual patients. In the case of predictive questions, there is much discussion as to what algorithm should be used to most accurately predict outcome. Aspects that determine usefulness of ML, compared with statistical techniques, include the volume of the data, the dimensionality of the preferred model, and the extent of missing data. There are areas in which modern ML methods may be preferred. However, efforts should be made to implement statistical frameworks (e.g., for dealing with missing data or measurement error, both omnipresent in clinical data) in ML methods. To conclude, there are important opportunities but also pitfalls to consider when performing clustering or predictive studies with ML techniques. We advocate careful valuation of new data-driven findings. More interaction is needed between the engineer mindset of experts in ML methods, the insight in bias of epidemiologists, and the probabilistic thinking of statisticians to extract as much information and knowledge from data as possible, while avoiding harm.

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.

Therapeutic potential of nociceptin/orphanin FQ peptide (NOP) receptor modulators for treatment of traumatic brain injury, traumatic stress, and their co-morbidities

The nociceptin/orphanin FQ (N/OFQ) peptide (NOP) receptor is a member of the opioid receptor superfamily with N/OFQ as its endogenous agonist. Wide expression of the NOP receptor and N/OFQ, both centrally and peripherally, and their ability to modulate several biological functions has led to development of NOP receptor modulators by pharmaceutical companies as therapeutics, based upon their efficacy in preclinical models of pain, anxiety, depression, Parkinson's disease, and substance abuse. Both posttraumatic stress disorder (PTSD) and traumatic brain injury (TBI) are debilitating conditions that significantly affect the quality of life of millions of people around the world. PTSD is often a consequence of TBI, and, especially for those deployed to, working and/or living in a war zone or are first responders, they are comorbid. PTSD and TBI share common symptoms, and negatively influence outcomes as comorbidities of the other. Unfortunately, a lack of effective therapies or therapeutic agents limits the long term quality of life for either TBI or PTSD patients. Ours, and other groups, demonstrated that PTSD and TBI preclinical models elicit changes in the N/OFQ-NOP receptor system, and that administration of NOP receptor ligands alleviated some of the neurobiological and behavioral changes induced by brain injury and/or traumatic stress exposure. Here we review the past and most recent progress on understanding the role of the N/OFQ-NOP receptor system in PTSD and TBI neurological and behavioral sequelae. There is still more to understand about this neuropeptide system in both PTSD and TBI, but current findings warrant further examination of the potential utility of NOP modulators as therapeutics for these disorders and their co-morbidities. We advocate the development of standards for common data elements (CDE) reporting for preclinical PTSD studies, similar to current preclinical TBI CDEs. That would provide for more standardized data collection and reporting to improve reproducibility, interpretation and data sharing across studies.

Balanced Electrolyte Solutions or Normal Saline? Resuscitative Fluid Administration Practice in Swiss Pediatric Acute Care: A Cross-Sectional Study

INTRODUCTION

The ideal asanguineous intravenous fluid for volume resuscitation in children is controversially debated and clinical practice guidelines are scarce. Administration of large amounts of normal saline has been associated with complications including hyperchloremic acidosis, dysnatremia, neurologic damage, and fatality.

AIM

We examined the current practice of intravenous fluid and blood product administration in acutely ill and injured children among pediatric acute care physicians in Switzerland.

METHODS

For this descriptive, cross-sectional study, pediatric emergency departments, pediatric and neonatal intensive care units were surveyed by means of an online questionnaire.

RESULTS

Sixty of 66 departments and 47 of 87 participants returned the survey. Normal saline (NS) was most commonly administered (n = 42/46, 91.3%) and twice as many times as balanced electrolyte solutions (n = 20/46, 43.5%). The mean fluid volumes ranged from 7.9 to 19.1 mL/kg. Hypertonic saline/NS were selected most often for shock with severe head injury. Half of participants administered colloids (48.9%). Packed red blood cells (97.7%) and fresh frozen plasma (88.4%) were most frequently given blood products.

CONCLUSION

There is a distinct practice variation in intravenous fluid and blood product administration in children in Switzerland. Although NS is most frequently given, we observed a trend toward the use of balanced electrolyte solutions. Prospective studies are warranted to compare NS with balanced electrolyte solution (BES) in the pediatric acute care setting. We suggest that pediatric fluid administration guidelines and mass transfusion protocols are implemented to standardize this frequent intervention and minimize complications.

Trauma-induced coagulopathy

Uncontrolled haemorrhage is a major preventable cause of death in patients with traumatic injury. Trauma-induced coagulopathy (TIC) describes abnormal coagulation processes that are attributable to trauma. In the early hours of TIC development, hypocoagulability is typically present, resulting in bleeding, whereas later TIC is characterized by a hypercoagulable state associated with venous thromboembolism and multiple organ failure. Several pathophysiological mechanisms underlie TIC; tissue injury and shock synergistically provoke endothelial, immune system, platelet and clotting activation, which are accentuated by the 'lethal triad' (coagulopathy, hypothermia and acidosis). Traumatic brain injury also has a distinct role in TIC. Haemostatic abnormalities include fibrinogen depletion, inadequate thrombin generation, impaired platelet function and dysregulated fibrinolysis. Laboratory diagnosis is based on coagulation abnormalities detected by conventional or viscoelastic haemostatic assays; however, it does not always match the clinical condition. Management priorities are stopping blood loss and reversing shock by restoring circulating blood volume, to prevent or reduce the risk of worsening TIC. Various blood products can be used in resuscitation; however, there is no international agreement on the optimal composition of transfusion components. Tranexamic acid is used in pre-hospital settings selectively in the USA and more widely in Europe and other locations. Survivors of TIC experience high rates of morbidity, which affects short-term and long-term quality of life and functional outcome.

Early Identification of Trauma-induced Coagulopathy: Development and Validation of a Multivariable Risk Prediction Model

OBJECTIVE

The aim of this study was to develop and validate a risk prediction tool for trauma-induced coagulopathy (TIC), to support early therapeutic decision-making.

BACKGROUND

TIC exacerbates hemorrhage and is associated with higher morbidity and mortality. Early and aggressive treatment of TIC improves outcome. However, injured patients that develop TIC can be difficult to identify, which may compromise effective treatment.

METHODS

A Bayesian Network (BN) prediction model was developed using domain knowledge of the causal mechanisms of TIC, and trained using data from 600 patients recruited into the Activation of Coagulation and Inflammation in Trauma (ACIT) study. Performance (discrimination, calibration, and accuracy) was tested using 10-fold cross-validation and externally validated on data from new patients recruited at 3 trauma centers.

RESULTS

Rates of TIC in the derivation and validation cohorts were 11.8% and 11.0%, respectively. Patients who developed TIC were significantly more likely to die (54.0% vs 5.5%, P < 0.0001), require a massive blood transfusion (43.5% vs 1.1%, P < 0.0001), or require damage control surgery (55.8% vs 3.4%, P < 0.0001), than those with normal coagulation. In the development dataset, the 14-predictor BN accurately predicted this high-risk patient group: area under the receiver operating characteristic curve (AUROC) 0.93, calibration slope (CS) 0.96, brier score (BS) 0.06, and brier skill score (BSS) 0.40. The model maintained excellent performance in the validation population: AUROC 0.95, CS 1.22, BS 0.05, and BSS 0.46.

CONCLUSIONS

A BN (http://www.traumamodels.com) can accurately predict the risk of TIC in an individual patient from standard admission clinical variables. This information may support early, accurate, and efficient activation of hemostatic resuscitation protocols.

Emergency sternal intraosseous access for warm fresh whole blood transfusion in damage control resuscitation

BACKGROUND

Intraosseous (IO) vascular access is increasingly used as an emergency tool for achieving access to the systemic circulation in critically ill patients. The role of IO transfusion of blood in damage control resuscitation is however questionable due to possible inadequate flow rate and hemolysis. Some experts claim that IO transfusion is contraindicated. In this study, we have challenged this statement by looking at flow rates of autologous fresh whole blood reinfusion and hemolysis using two of the commonly used Food and Drug Administration-approved and Conformité Européenne (CE)-marked sternal needles. Additionally, the success rate of sternal access between the two devices is evaluated.

METHODS

Volunteer professional military personnel, were enrolled prospectively in a nonrandomized observational study design. We collected 450 mL of autologous whole blood from each participant. Participants were divided into the following three groups of 10: Tactically Advanced Lifesaving IO Needle (T.A.L.O.N.) IO, FAST1 IO, and intravenous group. The reinfusion was done by gravity only. Blood sampling was performed before blood collection and 30 minutes after reinfusion. Investigation of hemolysis was performed by measurements of haptoglobin and lactate dehydrogenase. Success rate was evaluated by correct aspiration of bone marrow.

RESULTS

Median reinfusion rate was 46.2 mL/min in the FAST1 group, 32.4 mL/min in the T.A.L.O.N. group, and 74.1 mL/min in the intravenous group. Blood samples from all participants were within normal ranges. There was no statistically significant difference in haptoglobin and lactate dehydrogenase between the groups. In the FAST1 group, 1 (9%) of 11 procedures failed. In the T.A.L.O.N. group, 4 (29%) of 14 procedures failed.

CONCLUSION

Although preferable, achieving peripheral venous access in the bleeding patient is a major problem. Our findings suggest that fresh whole-blood transfusion through the IO route is safe, reliable, and provide sufficient flow for resuscitation.

LEVEL OF EVIDENCE

Therapeutic/Care management study, level III.

Trauma induced acute kidney injury

Background

Injured patients are at risk of developing acute kidney injury (AKI), which is associated with increased morbidity and mortality. The aim of this study is to describe the incidence, timing, and severity of AKI in a large trauma population, identify risk factors for AKI, and report mortality outcomes.

Methods

A prospective observational study of injured adults, who met local criteria for trauma team activation, and were admitted to a UK Major Trauma Centre. AKI was defined by the Kidney Disease Improving Global Outcomes (KDIGO) criteria. Multivariable logistic regression and Cox proportional hazard modelling was used to analyse parameters associated with AKI and mortality.

Results

Of the 1410 patients enrolled in the study, 178 (12.6%) developed AKI. Age; injury severity score (ISS); admission systolic blood pressure, lactate and serum creatinine; units of Packed Red Blood Cells transfused in first 24 hours and administration of nephrotoxic therapy were identified as independent risk factors for the development of AKI. Patients that developed AKI had significantly higher mortality than those with normal renal function (47/178 [26.4%] versus 128/1232 [10.4%]; OR 3.09 [2.12 to 4.53]; p<0.0001). After adjusting for other clinical prognostic factors, AKI was an independent risk factor for mortality.

Conclusions

AKI is a frequent complication following trauma and is associated with prolonged hospital length of stay and increased mortality. Future research is needed to improve our ability to rapidly identify those at risk of AKI, and develop resuscitation strategies that preserve renal function in trauma patients.

Isolated traumatic brain injury results in significant pre-hospital derangement of cardiovascular physiology

INTRODUCTION

Major trauma can result in both life-threatening haemorrhage and traumatic brain injury (TBI). The pre-hospital management of these conditions, particularly in relation to the cardiovascular system, is very different. TBI can result in cardiovascular instability but the exact incidence remains poorly described. This study explores the incidence of cardiovascular instability in patients undergoing pre-hospital anaesthesia for suspected TBI.

METHODS

Retrospective case series of all pre-hospital trauma patients attended by Kent, Surrey & Sussex Air Ambulance Trust (United Kingdom) trauma team during the period 1 January 2015-31 December 2016. Patients were included if they showed clinical signs of TBI, underwent pre-hospital anaesthesia and hospital computed tomography scanning subsequently confirmed an isolated TBI.

RESULTS

Out of 121 patients with confirmed isolated TBI, 68 were cardiovascularly stable throughout the pre-anaesthesia phase, whilst 53 (44%) showed signs of instability (HR > 100bpm and/or SBP < 100 mmHg pre-anaesthesia). Hypotension (SBP < 100) with or without tachycardia was present in 14 (12%) patients. 10 (8%) patients with isolated TBI received pre-hospital blood product transfusion.

CONCLUSION

Increased awareness that traumatic brain injury can cause significant derangement to heart rate and blood pressure, even in the absence of major haemorrhage, would allow the pre-hospital clinician to treat cardiovascular instability with the most appropriate means, such as crystalloid and vasopressors, to limit secondary brain injury.