1
|
Kuster M, Haltmeier T, Exadaktylos A, Schnüriger B. Non-invasive cardiac output monitoring device "ICON" in trauma patients: a feasibility study. Eur J Trauma Emerg Surg 2018; 45:1069-1076. [PMID: 30014271 DOI: 10.1007/s00068-018-0984-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 07/11/2018] [Indexed: 10/28/2022]
Abstract
PURPOSE Assessment of hemodynamics is crucial for the evaluation of major trauma patients. Cardiac output (CO) monitoring provides additional information and may improve volume resuscitation. The goal of this prospective pilot study was to evaluate the feasibility of a new non-invasive CO monitoring (NICOM) device in the emergency department (ED). METHODS Single-center prospective observational pilot study including 20 trauma patients admitted to a level 1 trauma center. CO was continuously monitored for 60 min after ED admission using the new NICOM device ICON®. This device measures changes of the thoracic bioimpedance to calculate CO. Conventional vital signs were recorded simultaneously. Feasibility, safety, reliability, user-friendliness, and impact of the device on standard ED procedures were assessed. RESULTS Thirteen (65%) patients were male, median age was 57.5 (IQR 25), and median ISS was 10.5 (IQR 14.8). Median CO over time was 9.8 l/min (IQR 4.6). No adverse effects were recorded. The device proved to be user-friendly with no negative impact on routine ED care. In four patients, detachment of electrodes was observed, and in four patients, the CO recording was temporary discontinued. Short-term changes of the CO were observed 44 times after the placement of electrodes and during patient transfers. CONCLUSIONS Non-invasive CO monitoring proved to be feasible and safe for the initial hemodynamic evaluation of trauma patients. Problems with the NICOM device were detachment of electrodes and temporary signal loss. Due to the small sample size and relatively low injury burden of the patients included in this study, further prospective investigation is warranted.
Collapse
Affiliation(s)
- Matthias Kuster
- Division of Acute Care Surgery, Department of Visceral and Transplant Surgery, Bern University Hospital, 3010, Bern, Switzerland
| | - Tobias Haltmeier
- Division of Acute Care Surgery, Department of Visceral and Transplant Surgery, Bern University Hospital, 3010, Bern, Switzerland
| | - Aristomenis Exadaktylos
- Department of Emergency Medicine, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Beat Schnüriger
- Division of Acute Care Surgery, Department of Visceral and Transplant Surgery, Bern University Hospital, 3010, Bern, Switzerland.
| |
Collapse
|
2
|
Kuster M, Exadaktylos A, Schnüriger B. Non-invasive hemodynamic monitoring in trauma patients. World J Emerg Surg 2015; 10:11. [PMID: 25774210 PMCID: PMC4359395 DOI: 10.1186/s13017-015-0002-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 01/28/2015] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND The assessment of hemodynamic status is a crucial task in the initial evaluation of trauma patients. However, blood pressure and heart rate are often misleading, as multiple variables may impact these conventional parameters. More reliable methods such as pulmonary artery thermodilution for cardiac output measuring would be necessary, but its applicability in the Emergency Department is questionable due to their invasive nature. Non-invasive cardiac output monitoring devices may be a feasible alternative. METHODS A systematic literature review was conducted. Only studies that explicitly investigated non-invasive hemodynamic monitoring devices in trauma patients were considered. RESULTS A total of 7 studies were identified as suitable and were included into this review. These studies evaluated in a total of 1,197 trauma patients the accuracy of non-invasive hemodynamic monitoring devices by comparing measurements to pulmonary artery thermodilution, which is the gold standard for cardiac output measuring. The correlation coefficients r between the two methods ranged from 0.79 to 0.92. Bias and precision analysis ranged from -0.02 +/- 0.78 l/min/m(2) to -0.14 +/- 0.73 l/min/m(2). Additionally, data on practicality, limitations and clinical impact of the devices were collected. CONCLUSION The accuracy of non-invasive cardiac output monitoring devices in trauma patients is broadly satisfactory. As the devices can be applied very early in the shock room or even preclinically, hemodynamic shock may be recognized much earlier and therapeutic interventions could be applied more rapidly and more adequately. The devices can be used in the daily routine of a busy ED, as they are non-invasive and easy to master.
Collapse
Affiliation(s)
- Matthias Kuster
- Department of Visceral and Transplant Surgery, Bern University Hospital, Bern, Switzerland
| | | | - Beat Schnüriger
- Department of Visceral and Transplant Surgery, Bern University Hospital, Bern, Switzerland ; Department of Visceral Surgery and Medicine, Bern University Hospital, Bern, Switzerland
| |
Collapse
|
3
|
Downs EA, Isbell JM. Impact of hemodynamic monitoring on clinical outcomes. Best Pract Res Clin Anaesthesiol 2014; 28:463-76. [PMID: 25480775 DOI: 10.1016/j.bpa.2014.09.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Revised: 09/25/2014] [Accepted: 09/29/2014] [Indexed: 01/19/2023]
Abstract
In recent years, there has been a tremendous growth in available hemodynamic monitoring devices to support clinical decision-making in the operating room and intensive care unit. In addition to the "tried and true" heart rate and blood pressure monitors, there are several newer applications of existing technologies including arterial waveform analysis, intraoperative and bedside critical care echocardiography, esophageal Doppler, and tissue oximetry, among others. Several monitoring devices demonstrate positive effect on outcomes, especially when used in conjunction with specific goal-directed therapy protocols to achieve a desired clinical effect. Other devices remain in the validation stage, awaiting comprehensive comparison to established techniques. While these new technologies offer promising advances in intraoperative and critical care, they are often quite costly and many devices lack strong evidence for widespread adoption into clinical practice. In this review, we highlight the current data on clinical outcomes with the use of available hemodynamic monitoring devices.
Collapse
Affiliation(s)
- Emily A Downs
- Division of Thoracic and Cardiovascular Surgery, Department of Surgery, University of Virginia, Charlottesville, VA 22908, USA.
| | - James M Isbell
- Division of Thoracic and Cardiovascular Surgery, Department of Surgery, University of Virginia, Charlottesville, VA 22908, USA.
| |
Collapse
|
4
|
Noninvasive monitoring of the autonomic nervous system and hemodynamics of patients with blunt and penetrating trauma. ACTA ACUST UNITED AC 2009; 65:1364-73. [PMID: 19077628 DOI: 10.1097/ta.0b013e31818cc307] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
BACKGROUND To describe early effects of sympathetic (SNS) and parasympathetic nervous system (PSNS) activities measured by heart rate (HR) and respiratory rate variabilities simultaneously with noninvasive hemodynamic patterns in patients with blunt and penetrating trauma. METHODS Descriptive study of 168 monitored trauma patients in a level I university-run trauma service. We studied HR and respiratory rate variability by spectral analysis as a measure of autonomic nervous system (ANS) activity in severe blunt and penetrating injuries beginning shortly after their admission to the emergency department. The low frequency area is the area under the HR spectral analysis curve within the frequency range of 0.04 Hz to 0.10 Hz. This area primarily reflects the tone of the SNS as mediated by the vagus nerve. The respiratory frequency area, sometimes referred to as the high frequency area, is a 0.12 Hz-wide frequency range centered around the fundamental respiratory frequency defined by the peak mode of the respiratory activity power spectrum. It is indicative of vagal outflow reflecting PSNS activity. The low frequency area/respiratory frequency area, or L/R ratio, reflects the balance of the SNS and the PSNS. ANS was studied simultaneously with noninvasive hemodynamic patterns after blunt and penetrating thoracic or abdominal injury beginning shortly after admission. We measured cardiac index by bioimpedance, HR, and mean arterial pressure (MAP) to evaluate cardiac function, pulse oximetry (SapO2) to reflect changes in respiratory function, and transcutaneous oxygen indexed to fractional inspired oxygen (PtcO2/FIO2) to reflect tissue perfusion. RESULTS ANS activity markedly increased especially in the nonsurvivors at 12 hours to 24 hours after admission. Compared with survivors, the nonsurvivors had lower MAP, CI, and PtcO2/FIO2 values associated with increased ANS activity. CONCLUSIONS In the nonsurvivors, low flow, low MAP, and reduced tissue perfusion were associated with pronounced increases in PSNS and lesser increases in SNS activity. In the survivors, higher CI, MAP, and PtcO2/FIO2 values were associated with lesser increases in both PSNS and SNS activities.
Collapse
|
5
|
Chien LC, Lu KJQ, Wo CCJ, Shoemaker WC. Hemodynamic patterns preceding circulatory deterioration and death after trauma. ACTA ACUST UNITED AC 2007; 62:928-32. [PMID: 17426550 DOI: 10.1097/01.ta.0000215411.92950.72] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To describe the sequence of hemodynamic changes associated with sudden circulatory deterioration compared with those of terminal patients to identify the earliest signs warning of shock and death. METHODS This is a prospective observational study of 89 patients with thermodilution cardiac index and continuous noninvasive hemodynamic monitoring who had episodes of circulatory deterioration. These data were compared with the data of a second group of 24 patients in their terminal stage just before death. RESULTS The earliest indications of impending collapse were decreased cardiac index, and tissue perfusion reflected by decreased transcutaneous O2 tension (PtcO2). This was followed by reduced blood pressure, tachycardia, reduced arterial hemoglobin saturation, and increased transcutaneous CO2 tension (PtcCO2). This pattern of changes was more pronounced in the nonsurvivors and was seen in exaggerated form in terminal patients. CONCLUSION Sequential hemodynamic patterns revealed reduced blood flow and poor tissue perfusion as the earliest warning signs in both circulatory deterioration and death. These were followed by reduced mean arterial pressure, tachycardia, and low values of pulse oximetry. Adequate blood flow and even distribution of flow are needed for tissue perfusion.
Collapse
Affiliation(s)
- Li-Chien Chien
- Division of Trauma/Critical Care, Department of Surgery, Keck School of Medicine, CA, USA
| | | | | | | |
Collapse
|
6
|
Yu M, Morita SY, Daniel SR, Chapital A, Waxman K, Severino R. Transcutaneous pressure of oxygen: a noninvasive and early detector of peripheral shock and outcome. Shock 2006; 26:450-6. [PMID: 17047514 DOI: 10.1097/01.shk.0000228798.18174.6a] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
A noninvasive tool to recognize early shock would improve outcome by providing prompt recognition of tissue ischemia and precise resuscitation endpoint. The skin is the first tissue bed to vasoconstrict in shock states. Studies have demonstrated that transcutaneous partial pressure of oxygen (PtCO2) increases with higher FiO2 in nonshock states as arterial pressure of oxygen (PaO2) increases, but in shock situations, PtCO2 mirrors changes in cardiac output and oxygen delivery with minimum response to increasing FiO2 and PaO2. This study examined the relationship of hemodynamic variables and the degree of PtCO2 response to FiO2 of 1.0 (identified as the "oxygen challenge test") to mortality and organ failure. This prospective observational study examined 38 patients requiring at least 24 h of cardiac output monitoring for shock resuscitation in the Surgical Intensive Care Unit. Patients were resuscitated to the standard protocol of blood pressure, urine output, oxygen delivery (DO2), and mixed venous O2 (SvO2). Seventy-nine percent of the patients (30/38) with a mean age of 59 +/- 21 years had septic shock or severe sepsis with a 26% mortality (10/38). Measurements included hemodynamic variables, PtCO2, and outcome (mortality and organ failure). In this study, the ability of PtCO2 value to increase by 21 mmHg on a FiO2 of 1.0, at 24 h of resuscitation, divided survivors from nonsurvivors, P <.001. The PtCO2 response to FiO2 may provide an additional noninvasive method of detecting early shock as well as a specific endpoint of resuscitation.
Collapse
Affiliation(s)
- Mihae Yu
- Department of Surgery and Division of Surgical Critical Care, University of Hawaii, 1356 Lusitana Street, Honolulu, HI 96813, USA.
| | | | | | | | | | | |
Collapse
|
7
|
Lu KJQ, Chien LC, Wo CCJ, Demetriades D, Shoemaker WC. Hemodynamic Patterns of Blunt and Penetrating Injuries. J Am Coll Surg 2006; 203:899-907. [PMID: 17116559 DOI: 10.1016/j.jamcollsurg.2006.08.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2006] [Revised: 08/01/2006] [Accepted: 08/01/2006] [Indexed: 10/24/2022]
Abstract
BACKGROUND The aims of this prospective observational study were to describe early hemodynamic patterns of blunt and penetrating truncal injury and to evaluate outcomes prediction using noninvasive hemodynamic monitoring with a mathematical model tested against actual in-hospital outcomes. The hypothesis was that traumatic shock is a circulatory disorder that can be monitored by noninvasive hemodynamic parameters that reflect cardiac, pulmonary, and tissue perfusion functions. STUDY DESIGN The cardiac index (CI), heart rate (HR), mean arterial pressure (MAP), pulse oximetry (SapO(2)), transcutaneous oxygen tension indexed to FiO(2) (PtcO(2)/FiO(2)), and carbon dioxide (PtcCO(2)) tensions were monitored beginning shortly after emergency department admission in 657 emergency patients with severe blunt and penetrating chest, abdominal, and extremity trauma. Of these, 113 patients had associated head injury, and these patients also were analyzed separately. A search and display mathematical model, with a decision support program, was based on continuous online, real-time, noninvasive hemodynamic monitoring. RESULTS There were similar patterns in the blunt and penetrating injuries; the cardiac index, mean arterial pressure, pulse oximetry, transcutaneous oxygen tension indexed to FiO(2), and survival probability values of the survivors were significantly higher (p < 0.01) than the corresponding values of those who died, although heart rate and carbon dioxide tension were higher in the nonsurvivors during the first 24 hours after their emergency department admission. These patterns occurred more rapidly in patients with penetrating injuries. After initial resuscitation in the emergency department, results were correlated with actual outcomes at hospital discharge and found to be 88% correct. CONCLUSIONS Early noninvasive hemodynamic monitoring with a computerized information system provided a feasible pattern recognition program for outcomes prediction and therapeutic decision support.
Collapse
Affiliation(s)
- Kevin Jun-Qiang Lu
- Department of Surgery, LAC+USC Medical Center, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
| | | | | | | | | |
Collapse
|
8
|
Martin M, Brown C, Bayard D, Demetriades D, Salim A, Gertz R, Azarow K, Wo CCJ, Shoemaker W. Continuous noninvasive monitoring of cardiac performance and tissue perfusion in pediatric trauma patients. J Pediatr Surg 2005; 40:1957-63. [PMID: 16338328 DOI: 10.1016/j.jpedsurg.2005.08.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
PURPOSE The aim of this study was to assess the accuracy of a continuous survival probability prediction using noninvasive measures of cardiac performance and tissue perfusion in severely injured pediatric patients. METHODS Review of all patients entered into a prospective noninvasive monitoring protocol. Cardiac index (CI) was measured using a thoracic bioimpedance device and tissue perfusion was assessed by transcutaneous carbon dioxide (Ptcco(2)) tension and oxygen tension indexed to the fraction of inspired oxygen (Ptco(2)/Fio(2)). Survival probability (SP) was continuously calculated using a stochastic analysis program. RESULTS There were 45 patients with a total of 953 data sets. The mean age was 11 years (range, 1-16 years) with a mean Injury Severity Score of 24 (+/-16). There was no difference between survivors (n = 32) and nonsurvivors (n = 13) at study entry for heart rate, blood pressure, CI, or pulse oximetry (all P > .05). However, survivors demonstrated higher Ptcco(2) (45 vs 35), higher Ptco(2)/Fio(2) (236 vs 156), and higher predicted SP (89% vs 62%) compared with nonsurvivors at study entry and throughout the monitoring period (all P < .01). For the entire data set, the strongest independent predictors of survival were Ptco(2)/Fio(2) and SP. The area under the receiver operating characteristic curve for mortality prediction was 0.83 for SP and 0.71 for Ptco(2)/Fio(2), compared with 0.6 for heart rate, 0.51 for blood pressure, and 0.53 for CI. Similar hemodynamic patterns were observed for all injury patterns with the exception of those with severe brain injury. CONCLUSIONS Thoracic bioimpedance and transcutaneous monitoring give critical real-time hemodynamic and tissue perfusion data that can provide early identification of pathologic flow patterns and accurately predict survival.
Collapse
Affiliation(s)
- Matthew Martin
- Division of Trauma and Surgical Critical Care, Los Angeles County Hospital + USC Medical Center, Los Angeles, CA 90033, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
9
|
|
10
|
Fontelles MJ, Mantovani M, Hirano ES, Morandin RC. Investigating the relationship between hemodynamic and metabolic parameters in portal triade occlusion following hemorrhagic shock. Acta Cir Bras 2005; 20:22-7. [PMID: 15810462 DOI: 10.1590/s0102-86502005000100005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023] Open
Abstract
PURPOSE: To determine whether metabolic and hemodynamic parameters are "mathematically" coupled in rats submitted to portal triad occlusion following controlled hemorrhagic shock state. METHODS: Pearson's coefficient (r-value) analysis was performed. Differences considered significant at p<0.05 and -0.50>r>0.50. RESULTS: It was observed that there is a direct proportional relationship to HCO3- with pCO2 (r=0.66), base deficit (r=0.87) and inverse with serum lactate (r=-0.54). pCO2 was directly associated with MAP (r=0.51), and inversely with pH (r=-0.64). Hematocrit was directly associated with HR (r=0.72) and CI (r=0.76), and serum lactated was inversely associated with base deficit (r=-0.61). CONCLUSION: In rats submitted to Pringle's maneuver during 15 minutes following hemorrhagic shock state, there is a mathematical coupling with a very good correlation between several hemodynamic and metabolic variables.
Collapse
Affiliation(s)
- Mauro José Fontelles
- Trauma Surgery Division, Department of Surgery, Faculty of Medical Sciences, Unicamp, Campinas, Brazil.
| | | | | | | |
Collapse
|
11
|
Brown CVR, Shoemaker WC, Wo CCJ, Chan L, Demetriades D. Is Noninvasive Hemodynamic Monitoring Appropriate for the Elderly Critically Injured Patient? ACTA ACUST UNITED AC 2005; 58:102-7. [PMID: 15674158 DOI: 10.1097/01.ta.0000105990.05074.4a] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Noninvasive hemodynamic monitoring in critically ill patients using bioimpedance technology has been shown to be a reliable alternative to invasive thermodilution techniques. However, there have been some concerns that the bioimpedance method may be unreliable in elderly patients with an atherosclerotic and rigid thoracic aorta. The purpose of the present study was to evaluate the effect of age on the reliability of noninvasive bioimpedance technology in measuring cardiac index. METHODS This is a retrospective analysis of prospectively collected data in critically injured patients admitted to the surgical intensive care unit. All patients had simultaneous measurement using thermodilution cardiac index (TDCI) and bioimpedance cardiac index (BICI). The population was divided into three age groups (<55 years, 55-70 years, and >70 years). The correlation between TDCI and BICI was calculated for each age group. RESULTS There were 1,138 simultaneous measurements of TDCI and BICI in 285 patients. The BICI correlated well with TDCI in all three age groups (r = 0.82 for group <55 years, r = 0.87 for group 55-70 years, and r = 0.80 for group >70 years). CONCLUSION Noninvasive cardiac index monitoring in elderly patients is reliable and correlates well with standard thermodilution techniques.
Collapse
Affiliation(s)
- Carlos V R Brown
- Department of Surgery, Division of Trauma and Critical Care, University of Southern California, Los Angeles, California 90033, USA.
| | | | | | | | | |
Collapse
|
12
|
Velmahos GC, Demetriades D, Shoemaker WC, Chan LS, Tatevossian R, Wo CC, Vassiliu P, Cornwell EE, Murray JA, Roth B, Belzberg H, Asensio JA, Berne TV. Endpoints of resuscitation of critically injured patients: normal or supranormal? A prospective randomized trial. Ann Surg 2000; 232:409-18. [PMID: 10973391 PMCID: PMC1421154 DOI: 10.1097/00000658-200009000-00013] [Citation(s) in RCA: 166] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To evaluate the effect of early optimization in the survival of severely injured patients. SUMMARY BACKGROUND DATA It is unclear whether supranormal ("optimal") hemodynamic values should serve as endpoints of resuscitation or simply as markers of the physiologic reserve of critically injured patients. The failure of optimization to produce improved survival in some randomized controlled trials may be associated with delays in starting the attempt to reach optimal goals. There are limited controlled data on trauma patients. METHODS Seventy-five consecutive severely injured patients with shock resulting from bleeding and without major intracranial or spinal cord trauma were randomized to resuscitation, starting immediately after admission, to either normal values of systolic blood pressure, urine output, base deficit, hemoglobin, and cardiac index (control group, 35 patients) or optimal values (cardiac index >4.5 L/min/m2, ratio of transcutaneous oxygen tension to fractional inspired oxygen >200, oxygen delivery index >600 mL/min/m2, and oxygen consumption index >170 mL/min/m2; optimal group, 40 patients). Initial cardiac output monitoring was done noninvasively by bioimpedance and, subsequently, invasively by thermodilution. Crystalloids, colloids, blood, inotropes, and vasopressors were used by predetermined algorithms. RESULTS Optimal values were reached intentionally by 70% of the optimal patients and spontaneously by 40% of the control patients. There was no difference in rates of death (15% optimal vs. 11% control), organ failure, sepsis, or the length of intensive care unit or hospital stay between the two groups. Patients from both groups who achieved optimal values had better outcomes than patients who did not. The death rate was 0% among patients who achieved optimal values compared with 30% among patients who did not. Age younger than 40 years was the only independent predictive factor of the ability to reach optimal values. CONCLUSIONS Severely injured patients who can achieve optimal hemodynamic values are more likely to survive than those who cannot, regardless of the resuscitation technique. In this study, attempts at early optimization did not improve the outcome of the examined subgroup of severely injured patients.
Collapse
Affiliation(s)
- G C Velmahos
- Department of Surgery, Division of Trauma and Critical Care, and the Department of Biostatistics and Outcomes Research, University of Southern California, Los Angeles, California, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|