Current status of point of care ultrasonography for the perioperative care of trauma patients

PURPOSE OF REVIEW

The incorporation of point of care ultrasound into the field of anesthesiology and perioperative medicine is growing at rapid pace. The benefits of this modality align with the acuity of patient care and decision-making in anesthetic care of a trauma patient.

RECENT FINDINGS

Cardiac ultrasound can be used to diagnose cardiac tamponade or investigate the inferior vena cava to assess volume status in patients who may suffer from hemorrhagic shock. Thoracic ultrasound may be used to rapidly identify pneumothorax or hemothorax in a patient suffering chest wall trauma. In addition, investigators are exploring the utility of ultrasonography in traumatic airway management and elevated intracranial pressure. In addition, the utility of gastric ultrasound on trauma patients is briefly discussed.

SUMMARY

Incorporation of point of care ultrasound techniques into the practice of trauma anesthesiology is important for noninvasive, mobile and expeditious assessment of trauma patients. In addition, further large-scale studies are needed to investigate how point of care ultrasound impacts outcomes in trauma patients.

TFAST Accurate Diagnosis of Pleural and Pericardial Effusion, Caudal Vena Cava in Dogs and Cats

TFAST, a standardized and validated thoracic point-of-care ultrasound examination, includes 5 acoustic windows: bilaterally applied chest tube site and pericardial site views plus diaphragmatico-hepatic view, also part of AFAST/ Vet BLUE. TFAST is used for rapid detection of pneumothorax and pleural and pericardial effusion. By following a set of TFAST rules, image interpretation errors are avoided, including mistaking cardiac chambers for effusion. Moreover, TFAST echocardiography is used as a screening test for chamber size and soft tissue abnormalities, volume status and contractility, and intracardiac abnormalities.

Thirteen dogs and a cat with ultrasonographically detected gallbladder wall edema associated with cardiac disease

Background

Ultrasonographically detected gallbladder wall edema (GBWE) is a marker for anaphylaxis in dogs. Cardiac disease can cause GBWE with similar signs and should be included as a differential diagnosis to prevent interpretation errors.

Hypothesis/Objectives

Document GBWE associated with cardiac disease.

Animals

Fourteen client‐owned animals.

Methods

Prospective case series with abdominal focused assessment with abdominal sonography in trauma, triage and tracking (AFAST), and thoracic focused assessment with abdominal sonography in trauma, triage, and tracking (TFAST) performed at triage. Animals with GBWE and cardiac disease were enrolled. A board‐certified radiologist reviewed images to confirm cardiac disease, GBWE, and characterize the caudal vena cava (CVC) and hepatic veins.

Results

Thirteen dogs and 1 cat had GBWE associated with cardiac disease. Gallbladder findings included mural thickness ranging from 3 to 5 mm, mild to moderate sludge (n = 3), and mild to moderate luminal distension (n = 6). CVC and hepatic venous distension were found in 5/6. Cardiac diagnoses in dogs included 11 with pericardial effusion (PCE) and 1 each with dilated cardiomyopathy and right‐sided myocardial failure. Severity of PCE was rated as mild (n = 1), moderate (n = 6), or severe (n = 4). Seven of 11 had pericardiocentesis performed. Nine of 13 had ascites with 4 having abdominal fluid scores of 1 (n = 2), 2 (n = 2), 3 (n = 1), and 4 (n = 0). Lung ultrasound findings were as follows: dry lung (n = 6), B‐lines (n = 4), and nodules (n = 1). The cat had moderate PCE, ascites scored as 1, and severe right‐sided ventricular enlargement associated with a ventricular septal defect. Primary presenting complaints included acute weakness (n = 9), acute collapse (n = 5), gastrointestinal signs (n = 3), respiratory distress (n = 2), and need for cardiopulmonary resuscitation (n = 1).

Conclusions and Clinical Importance

Ultrasonographically detected GBWE was associated with PCE in this small cohort of cases.

Cageside Ultrasonography in the Emergency Room and Intensive Care Unit

Global Focused Assessment with Sonography for Trauma (FAST) and point-of-care ultrasonography carry the potential to screen for and monitor conditions rather than traditional means without ultrasonography. Advantages include being point of care, cageside, low impact, rapid, safe, and radiation sparing, and requiring no shaving and/or minimal patient restraint. Moreover, information is real time for free fluid and soft tissue abnormalities of the abdomen, heart, and lung, which are missed or only suspected by physical examination, basic blood and urine testing, and radiography. A standardized approach with recording of patient data is integral to a successful Global FAST program.

[Index from Diameter of Inferior Vena Cava and Abdominal Aorta of Newborns - A Relevant Method for Evaluation of Hypovolemia]

Hypovolemia is one of the important problems in sick neonates. Ultrasound is a safe, noninvasive diagnostic tool for the assessment of volume status. For that reason, the aim of the study was to determine normal values of the diameter of inferior vena cava (IVC), abdominal aorta (Ao) and the index IVC/Ao.

PATIENTS AND METHODS

97 healthy, term neonates were included in the study and investigated at first and third day of life. The diameter of IVC, Ao was measured and the index from IVC/Ao was estimated. Using statistics mean and median values of the parameters and correlations to birth weight were determined.

RESULTS

Diameter of Ao at first day was 6.1 (+/-0.6) mm and at third day 6.2 (+/-0.6) mm, of IVC at first day was 2.5 (+/-0.5) and at third day 2.61 (+/-0.5). The Index from diameters of IVC/Ao was evaluated at day 1 as 0.4 (+/-0.1) and day 3 as 0.4 (+/-0.1). We found a positive correlation to the birth weight. We identified a significant difference of the index in SGA and LGA - neonates (0.36 vs 0.47). Despite a significant reduced weight from first to third day in the neonates, we determined no influence on the diameter of IVC, Ao and the index IVC/Ao.

CONCLUSION

We determined normal values of diameter of IVC and Ao and the Index of IVC/Ao. It is our opinion, that it is possible to assess the intravascular volume using the index. The importance of the index can be underlined by the results in SGA-neonates. More research is needed to understand some points of the pathophysiology in SGA.

Results of a Prospective Study to Evaluate the Impact of Point-of-Care Ultrasound in the Enhancement of Gastrointestinal Bleeding Risk Scores

OBJECTIVES

Gastrointestinal (GI) bleeding is a common illness seen in the emergency department. The prognosis varies from self-limited to potentially life threatening. Currently available GI bleeding risk scores have only a modest predictive value, limiting their wide implementation. The aim of this study was to assess the association and capability of point-of-care ultrasound (POCUS) used by emergency physicians to improve common GI bleeding scores for predicting complications and long-term outcomes of patients with GI bleeding, which to our knowledge have never been studied.

METHODS

Between August 2015 and April 2017, 203 hemodynamically stable patients with acute GI bleeding admitted to the emergency department were prospectively investigated. Using ultrasound, we measured the inferior vena cava diameter, cardiac output with surrogate markers such as the velocity time integral before and after the passive leg-raising test, and the presence of systolic obliteration of the left ventricle. The Rockall and Glasgow-Blatchford scores were calculated for patients with upper GI bleeding and the Velayos score for lower GI bleeding. The patients had follow-up during hospitalization and 30 days later to assess for early and late adverse events (AEs). Then we integrated the ultrasound findings of hypovolemia into the GI bleeding scores, assessing the capability to detect AEs.

RESULTS

In our cohort, patients with upper GI bleeding who showed left ventricle kissing walls had a worse evolution, with a greater presence of late AEs (odds ratio [OR], 3.8; 95% confidence interval [CI], 1.32-10.96; P = .01). Patients with lower GI bleeding who showed a collapse of the inferior vena cava (>50%) after passive leg raising had a greater presence of early AEs (OR, 3.6; 95% CI, 1.46-9.00; P = .004). The predictive performance of the Rockall score (receiver operating characteristic analysis: area under the curve [AUC], 77.6%; 95% CI, 66.3%-88.8%) increased with POCUS (AUC, 80.3%; 95% CI, 69.5%-91.1%); that of the Glasgow-Blatchford score (AUC, 72.5%; 95% CI, 59.9%-85.2%) increased with POCUS (AUC, 73.2%; 95% CI, 61.1%-85.4%); and that of Velayos score (AUC, 55.7%; 95% CI, 42.5%-69.0%) also increased with POCUS (AUC, 72.2%; 95% CI, 61.1%-83.3%).

CONCLUSIONS

The use of POCUS in GI bleeding is feasible and enhances common GI bleeding risk scores, showing better predictive performance in detecting AEs.

Inferior Vena Cava Volume Is an Independent Predictor of Massive Transfusion in Patients With Trauma

OBJECTIVES

Early adequate resuscitation of patients with trauma is crucial in preventing shock and early mortality. Thus, we aimed to determine the performance of the inferior vena cava (IVC) volume and other risk factors and scores in predicting massive transfusion and mortality.

METHODS

We included all patients with trauma who underwent computed tomography (CT) scan of the torso, which included the abdominal area, in our emergency department (ED) from January 2014 to January 2017. We calculated the 3-dimensional IVC volume from the left renal vein to the IVC bifurcation. The primary outcome was the performance of IVC volume in predicting massive transfusion, and the secondary outcome was the performance of IVC volume in predicting 24-hour and 30-day in-hospital mortality.

RESULTS

Among the 236 patients with trauma, 7.6% received massive transfusions. The IVC volume and revised trauma score (RTS) were independent predictors of massive transfusion (adjusted odds ratio [OR]: 0.79 vs 1.86, 95% confidence interval [CI], 0.71-0.89 vs 1.4-2.47, respectively). Both parameters showed the good area under the curve (AUC) for the prediction of massive transfusion (adjusted AUC: 0.83 and 0.82, 95% CI, 0.74-0.92 vs 0.72-0.93, respectively). Patients with a large IVC volume (fourth quartile) were less likely to receive massive transfusion than those with a small IVC volume (first quartile, ≥28.29 mL: 0% vs <15.08 mL: 20.3%, OR: 0.13, 95% CI, 0.03-0.66).

CONCLUSIONS

The volume of IVC measured on CT scan and RTS are independent predictors of massive transfusion in patients with trauma in the ED.

Veterinary-focused assessment with sonography for trauma-airway, breathing, circulation, disability and exposure: a prospective observational study in 64 canine trauma patients

OBJECTIVE

To describe the technique and findings of the 'veterinary focused assessment with sonography for trauma-airway, breathing, circulation, disability and exposure' protocol in dogs suffering from trauma.

MATERIALS AND METHODS

Prospective observational study on a new point-of-care ultrasound protocol on 64 dogs suffering from trauma and comparison of findings with radiology.

RESULTS

Comparison of the results of this new ultrasound protocol for trauma patients with radiography findings for pneumothorax, pleural effusion, alveolar-interstitial syndrome and abdominal effusion revealed positive agreement of 89, 83, 100 and 87% and negative agreement of 76, 83, 76 and 92%, respectively. Novel findings of the 'veterinary focused assessment with sonography for trauma-airway, breathing, circulation, disability and exposure' exam, which were not previously reported for dogs undergoing focused assessment with sonography for trauma, included alveolar-interstitial syndrome (suggestive of pulmonary contusions), diaphragmatic hernia, retroperitoneal effusion and tracheal injury. Our new technique may also help identify increased intracranial pressure via changes in optic nerve sheath diameter and haemodynamic instability through the evaluation of the caudal vena cava and cardiac function.

CLINICAL SIGNIFICANCE

The described ultrasound examination protocol can be rapidly performed on dogs suffering from trauma during resuscitation and it may detect injuries previously undetectable using other veterinary point-of-care ultrasound protocols.

Right ventricular fractional area of change is predictive of ventilator support days in trauma and burn patients

Echocardiography has contributed to the care of critically ill patients but there remains a need for more publications about its association with outcomes to confirm its role. We conducted a retrospective review of trauma and burn patients that were admitted to our intensive care unit between 2015 and 2017 that underwent hemodynamic transesophageal echocardiography. Data collected included demographics, clinical and laboratory data. Right ventricle fractional area of change (RVFAC) measurements were performed on still mages obtained from mid-esophageal four-chamber-view clips. There were 74 patients, mean age was 51 years, and were predominantly white and male. Linear regression was used to test for the association between RVFAC and clinical outcomes. Adjusting for age, injury mechanism and injury severity, higher RVFAC was significantly associated with lower ventilator days (p = 0.03). Conclusion, higher right ventricle systolic function is associated with a lower number of ventilator support days in critically injured trauma and burn patients.

Image-Guided Resuscitation With Limited Transthoracic Echocardiogram in Pediatric Trauma Patients

INTRODUCTION

Limited transthoracic echocardiogram (LTTE) has been shown to be a useful tool in guiding resuscitation in adult trauma patients. Our hypothesis is that image-guided resuscitation in pediatric trauma patients with LTTE is feasible.

METHODS

A retrospective chart review was performed on highest level pediatric trauma alerts (age 18 years or younger) at our level I trauma center during a 6-month period. Patients were divided into 2 groups as follows: those who had LTTE performed (LTTE group) and those who did not have LTTE performed (non-LTTE group).

RESULTS

A total of 31 charts were reviewed; 4 patients were excluded because they died on arrival to the emergency department. Fourteen patients had LTTE performed (LTTE group); 13 patients did not have LTTE performed (non-LTTE group). There was no difference in mechanism of injury, age, injury severity score, weight, or intensive care unit admission between the groups. The LTTE group received significantly less intravenous fluid than the non-LTTE group (1.2 vs 2.3 L, P = 0.0013).Within the LTTE group, 8 patients had "full" inferior vena cava (IVC) and 6 patients had "empty" IVC. There was no difference in injury severity score between these subgroups (P = 0.1018). Less fluid was given in the group labeled with full IVC [1.1 L (0.8-1.2)] than the group with empty IVC [2.4 L (1.7-2.6)], P = 0.0005. Four of the 6 patients with "empty" IVC had a confirmed source of bleeding.

CONCLUSIONS

Limited transthoracic echocardiogram can limit the amount of unnecessary crystalloid resuscitation given to pediatric trauma patients who are not hypovolemic.

4107 Limited Echocardiogram Examinations Performed by Intensivists: A Surgeon-Driven Multidisciplinary Program

Limited transthoracic echocardiogram (LTTE) has been introduced as a tool to direct resuscitation. At our institution, a multidisciplinary training program was instituted. Our hypothesis is that in spite all efforts for multidisciplinary training, certification, and credentialing, limited echocardiograms are under billed for. A training program was implemented in August 2010. This was followed by a process of credentialing and adding LTTE to the billing privileges for providers. Institutional Review Board approval was obtained to review all the studies performed from August 2010 to October 2014. About 4107 LTTEs were performed during the study period. Only 685 examinations were billed for (16.6%). The total amount billed for all the studies was $80,819.00. The number of studies billed for and performed in the emergency department (ED) were 342, and 343 studies were billed while performed in the intensive care unit (ICU). Our institution received payment at a higher rate when the studies were performed in the ICU (71.7%) versus ED (49.4%), P < 0.0001. The total actual reimbursement for the ED was $6487.29 and for the ICU was $8213.95 for a total of $14,701.24. The mean reimbursement amount was $35.59. If all of the studies were billed for and reimbursed at the average payment amount, the institution would have received $146,168.13. A multidisciplinary approach is pivotal for the success of intensivist-driven bedside echocardiogram programs. Education regarding credentialing and billing is a necessary addition to ensure sustainability of such efforts.

Endpoints in resuscitation

PURPOSE OF REVIEW

Shock occurs because of a failure to deliver adequate oxygen to meet the metabolic demands of the body resulting in metabolic acidosis, inflammation, and coagulopathy. Resuscitation is the process of treating shock in an attempt to restore normal physiology. Various hemodynamic, metabolic, and regional endpoints have been described to evaluate the degree of shock and guide resuscitation efforts. We will briefly describe these endpoints, and propose damage control resuscitation as an additional endpoint.

RECENT FINDINGS

Serum lactate, base deficit, and pH are well established endpoints of resuscitation that provide valuable information when trended over time; however, a single value is inadequate to determine adequacy of resuscitation. Rapid normalization of central venous oxygen concentration has been associated with improved survival, and bedside transthoracic echocardiography can be a reliable assessment of volume status. In hypovolemic/hemorrhagic shock, early hypotensive, or controlled resuscitation strategies have been associated with improved survival, and hemostatic strategies guided by thrombelastography using a balanced transfusion approach result in improved hemostasis.

SUMMARY

Numerous endpoints are available; however, no single endpoint is universally applicable. Damage control resuscitation strategies have demonstrated improved survival, hemostasis, and less early death from exsanguination, suggesting that hemorrhage control should be an additional endpoint in resuscitation.

Image-based resuscitation of the hypotensive patient with cardiac ultrasound: An evidence-based review

This article is a detailed review of the literature regarding the use of cardiac ultrasound for the resuscitation of hypotensive patients. In addition, figures regarding windows and description of how to perform the test are included.

Dynamic behavior of venous collapsibility and central venous pressure during standardized crystalloid bolus: A prospective, observational, pilot study

INTRODUCTION

Measurement of intravascular volume status is an ongoing challenge for physicians in the surgical intensive care unit (SICU). Most surrogates for volume status, including central venous pressure (CVP) and pulmonary artery wedge pressure, require invasive lines associated with a number of potential complications. Sonographic assessment of the collapsibility of the inferior vena cava (IVC) has been described as a noninvasive method for determining volume status. The purpose of this study was to analyze the dynamic response in IVC collapsibility index (IVC-CI) to changes in CVP in SICU patients receiving fluid boluses for volume resuscitation.

MATERIALS AND METHODS

A prospective pilot study was conducted on a sample of SICU patients who met clinical indications for intravenous (IV) fluid bolus and who had preexisting central venous access. Boluses were standardized to crystalloid administration of either 500 mL over 30 min or 1,000 mL over 60 min, as clinically indicated. Concurrent measurements of venous CI (VCI) and CVP were conducted right before initiation of IV bolus (i.e. time 0) and then at 30 and 60 min (as applicable) after bolus initiation. Patient demographics, ventilatory parameters, and vital sign assessments were recorded, with descriptive outcomes reported due to the limited sample size.

RESULTS

Twenty patients received a total of 24 IV fluid boluses. There were five recorded 500 mL boluses given over 30 min and 19 recorded 1,000 mL boluses given over 60 min. Mean (median) CVP measured at 0, 30, and 60 minutes post-bolus were 6.04 ± 3.32 (6.5), 9.00 ± 3.41 (8.0), and 11.1 ± 3.91 (12.0) mmHg, respectively. Mean (median) IVC-CI values at 0, 30, and 60 min were 44.4 ± 25.2 (36.5), 26.5 ± 22.8 (15.6), and 25.2 ± 21.2 (14.8), respectively.

CONCLUSIONS

Observable changes in both VCI and CVP are apparent during an infusion of a standardized fluid bolus. Dynamic changes in VCI as a measurement of responsiveness to fluid bolus are inversely related to changes seen in CVP. Moreover, an IV bolus tends to produce an early response in VCI, while the CVP response is more gradual. Given the noninvasive nature of the measurement technique, VCI shows promise as a method of dynamically measuring patient response to fluid resuscitation. Further studies with larger sample sizes are warranted.

Use of limited transthoracic echocardiography in patients with traumatic cardiac arrest decreases the rate of nontherapeutic thoracotomy and hospital costs

OBJECTIVES

Limited transthoracic echocardiography (LTTE) has been introduced as a hemodynamic tool for trauma patients. The aim of this study was to evaluate the utility of LTTE during the evaluation of nonsurviving patients who presented to the trauma bay with traumatic cardiac arrest.

METHODS

Approval by the Institutional Review Board was obtained. All nonsurviving patients with traumatic cardiac arrest who reached the trauma bay were evaluated retrospectively for 1 year. Comparisons between groups of patients in whom LTTE was performed as part of the resuscitation effort and those in whom it was not performed were conducted.

RESULTS

From January 2012 to January 2013, 37 patients did not survive traumatic cardiac arrest while in the trauma bay: 14 in the LTTE group and 23 in the non-LTTE group. When comparing the LTTE and non-LTTE groups, both were similar in sex distribution (LTTE, 86% male; non-LTTE, 74% male; P = .68), age (34.8 versus 24.1 years; P= .55), Injury Severity Score (41.0 versus 38.2; P= .48), and percentage of penetrating trauma (21.6% versus 21.7%; P = .29). Compared with the non-LTTE group, the LTTE group spent significantly less time in the trauma bay (13.7 versus 37.9 minutes; P = .01), received fewer blood products (7.1% versus 31.2%; P = .789), and were less likely to undergo nontherapeutic thoracotomy in the emergency department (7.14% versus 39.1%; P < .05). The non-LTTE group had a mean of $3040.50 in hospital costs, compared with the mean for the LTTE group of $1871.60 (P = .0054).

CONCLUSIONS

In this study, image-guided resuscitation with LTTE decreased the time in the trauma bay and avoided nontherapeutic thoracotomy in nonsurviving trauma patients. Limited TTE could improve the use of health care resources in patients with traumatic cardiac arrest.

The FAST and E-FAST in 2013: trauma ultrasonography: overview, practical techniques, controversies, and new frontiers

This article reviews important literature on the FAST and E-FAST examinations in adults. It also reviews key pitfalls, limitations, and controversies. A practical "how-to" guide is presented. Lastly, new frontiers are explored.

Flat or fat? Inferior vena cava ratio is a marker for occult shock in trauma patients

BACKGROUND

Identification of occult shock (OS) or hypoperfusion is critical in the initial management of trauma patients. Analysis of inferior vena cava (IVC) ratio on computed tomography (CT) scan has shown promise in predicting intravascular volume. We hypothesized that a flat IVC is a predictor of OS and associated with worse outcomes in major trauma patients.

MATERIALS AND METHODS

We performed a 1-y retrospective analysis of our level 1 trauma center database to identify all major trauma activations that underwent evaluation with a CT scan of the torso, arterial blood gas, and serum lactate. A flat IVC was defined as a transverse-to-anteroposterior ratio ≥2.5 at the level of the suprarenal IVC. OS was defined as a base deficit ≥4.0 in the absence of hypotension (systolic blood pressure ≤90 mm Hg).

RESULTS

Two hundred sixty-four patients were included, of which 52 had a flat IVC. Patients with a flat IVC were found to have a higher injury severity score, lactate, and base deficit compared with patients with a fat IVC. Flat IVC patients also required greater amounts of fluids (P < 0.04) and blood (P < 0.01). On multivariate analysis, a flat IVC was independently associated with an increased risk for OS (odds ratio = 2.87, P < 0.007) and overall complications (odds ratio = 2.26, P = 0.05). The area under the receiver operating characteristic curve for a flat IVC to predict OS was 0.74.

CONCLUSIONS

A flat IVC on CT is an accurate marker for OS in major trauma victims and may help stratify patients who require more aggressive resuscitation, monitoring, and support.

Findings of a randomized controlled trial using limited transthoracic echocardiogram (LTTE) as a hemodynamic monitoring tool in the trauma bay

BACKGROUND

We hypothesize that limited transthoracic echocardiogram (LTTE) is a useful tool to guide therapy during the initial phase of resuscitation in trauma patients.

METHODS

All highest-level alert patients with at least one measurement of systolic blood pressure less than 100 mm Hg, a mean arterial pressure less than 60 mm Hg, and/or a heart rate greater than 120 beats per minute who arrived to the trauma bay (TB) were randomized to have either LTTE performed (LTTEp) or not performed (non-LTTE) as part of their initial evaluation. Images were stored, and results were reported regarding contractility (good vs. poor), fluid status (empty inferior vena cava [hypovolemic] vs. full inferior vena cava [not hypovolemic]), and pericardial effusion (present vs. absent). Time from TB to operating room, intravenous fluid administration, blood product requirement, intensive care unit admission, and mortality were examined in both groups.

RESULTS

A total of 240 patients were randomized. Twenty-five patients were excluded since they died upon arrival to the TB, leaving 215 patients in the study. Ninety-two patients were in the LTTEp group with 123 patients in the non-LTTE group. The LTTEp and non-LTTE groups were similar in age (38 years vs. 38.8 years, p = 0.75), Injury Severity Score (ISS) (19.2 vs. 19.0, p = 0.94), Revised Trauma Score (RTS) (5.5 vs. 6.0, p = 0.09), lactate (4.2 vs. 3.6, p = 0.14), and mechanism of injury (p = 0.44). Strikingly, LTTEp had significantly less intravenous fluid than non-LTTE patients (1.5 L vs. 2.5 L, p < 0.0001), less time from TB to operating room (35.6 minutes vs. 79.1 min, p = 0.0006), higher rate of intensive care unit admission (80.4% vs. 67.2%, p = 0.04), and a lower mortality rate (11% vs. 19.5%, p = 0.09). Mortality differences were particularly evident in the traumatic brain injury patients (14.7% in LTTEp vs. 39.5% in non-LTTE, p = 0.03).

CONCLUSION

LTTE is a useful guide for therapy in hypotensive trauma patients during the early phase of resuscitation.

LEVEL OF EVIDENCE

Therapeutic study, level II.