Occult Shock Research Articles

Right Ventricular-Pulmonary Arterial Uncoupling as a Predictor of Invasive Hemodynamics and Normotensive Shock in Acute Pulmonary Embolism

Right ventricular-pulmonary arterial (RV-PA) coupling describes the relationship between RV contractility and its afterload and is estimated as the ratio of the tricuspid annular plane systolic excursion (TAPSE) to pulmonary arterial systolic pressure (PASP) via echocardiography. Whether TAPSE/PASP is reflective of invasive hemodynamics or occult shock in acute pulmonary embolism (PE) is unknown. This was a single-center retrospective study over a 3-year period of consecutive patients with PE undergoing mechanical thrombectomy and simultaneous pulmonary artery catheterization with echocardiograms performed within 24 hours prior to the procedure.Seventy patients (81% intermediate-risk) had complete invasive hemodynamic profiles and echocardiograms with TAPSE/PASP calculated. The optimal cutoff for TAPSE/PASP as a predictor of a reduced cardiac index (CI≤ 2.2 L/min/m2) was 0.34 mm/mmHg with an AUC of 0.97 and sensitivity, specificity, positive predictive value, and negative predictive value of 97.3%, 90.9%, 92.3% and 96.8%, respectively. Every 0.1 mm/mmHg decrease in TAPSE/PASP was associated with a 0.24 L/min/m2 decrease in the CI. This relationship was similar when restricted to intermediate-risk PE. The TAPSE/PASP ratio was predictive of normotensive shock with an OR 2.63 (95% CI: 1.42, 4.76, p=0.002) per unit decrease in the ratio.In conclusion, patients with acute PE undergoing mechanical thrombectomy, TAPSE/PASP was a strong predictor of a reduced CI and normotensive shock. This means of non-invasive point-of-care assessment of hemodynamics may have added value in PE risk stratification.

267 Identifying Occult Shock in Young Trauma Patients Using Logistic Regression Analysis of the 2020 National Trauma Data Bank

267 Identifying Occult Shock in Young Trauma Patients Using Logistic Regression Analysis of the 2020 National Trauma Data Bank

Alterations in tissue oxygen saturation measured by near-infrared spectroscopy in trauma patients after initial resuscitation are associated with occult shock

PurposePersistent occult hypoperfusion after initial resuscitation is strongly associated with increased morbidity and mortality after severe trauma. The objective of this study was to analyze regional tissue oxygenation, along with other global markers, as potential detectors of occult shock in otherwise hemodynamically stable trauma patients.MethodsTrauma patients undergoing active resuscitation were evaluated 8 h after hospital admission with the measurement of several global and local hemodynamic/metabolic parameters. Apparently hemodynamically stable (AHD) patients, defined as having SBP ≥ 90 mmHg, HR < 100 bpm and no vasopressor support, were followed for 48 h, and finally classified according to the need for further treatment for persistent bleeding (defined as requiring additional red blood cell transfusion), initiation of vasopressors and/or bleeding control with surgery and/or angioembolization. Patients were labeled as “Occult shock” (OS) if they required any intervention or “Truly hemodynamically stable” (THD) if they did not. Regional tissue oxygenation (rSO2) was measured non-invasively by near-infrared spectroscopy (NIRS) on the forearm. A vascular occlusion test was performed, allowing a 3-min deoxygenation period and a reoxygenation period following occlusion release. Minimal rSO2 (rSO2min), Delta-down (rSO2–rSO2min), maximal rSO2 following cuff-release (rSO2max), and Delta-up (rSO2max–rSO2min) were computed. The NIRS response to the occlusion test was also measured in a control group of healthy volunteers.ResultsSixty-six consecutive trauma patients were included. After 8 h, 17 patients were classified as AHD, of whom five were finally considered to have OS and 12 THD. No hemodynamic, metabolic or coagulopathic differences were observed between the two groups, while NIRS-derived parameters showed statistically significant differences in Delta-down, rSO2min, and Delta-up.ConclusionsAfter 8 h of care, NIRS evaluation with an occlusion test is helpful for identifying occult shock in apparently hemodynamically stable patients.Level of evidenceIV, descriptive observational study.Trial registrationClinicalTrials.gov Registration Number: NCT02772653.

Outcomes and Factors Associated with Occult Septic Shock in Emergency Department Patients with Soft Tissue Infection

Patients who develop occult septic shock (OSS) are associated with worse outcomes than those with early septic shock (ESS). Patients with skin and soft tissue infection (SSTI) may have underlying organ dysfunction due to OSS, yet the prevalence and the outcomes of patients with SSTI and early versus occult shock have not been described. This study compared the clinical characteristics of SSTI patients and the prevalence of having no septic shock (NSS), ESS, or OSS. We retrospectively analyzed charts of adult patients who were transferred from any emergency department to our academic center between January 1, 2014, and December 31, 2016. Outcomes of interest were the development of OSS and acute kidney injury (AKI). We performed logistic regressions to measure the association between clinical factors with the outcomes and created probability plots to show the relationship between key clinical variables and outcomes of OSS or AKI. Among 269 patients, 218 (81%) patients had NSS, 16 (6%) patients had ESS, and 35 (13%) patients had OSS. Patients with OSS had higher mean serum lactate concentrations than patients with NSS (3.5 vs. 2.1 mmol/L, P < 0.01). Higher sequential organ failure assessment (SOFA) score was associated with higher likelihood of developing OSS (odds ratio [OR] 1.41, 95% confidence interval [CI] 1.23-1.62, P < 0.001). NSS was associated with very low odds of developing AKI (OR 0.16, 95% CI 0.08-0.33, P < 0.001). 13% of the patients with SSTI developed OSS. Patients with OSS had elevated serum lactate concentration and higher SOFA score than those with NSS. Increased SOFA score is a predictor for the development of OSS.

Prehospital end-tidal carbon dioxide is predictive of death and massive transfusion in injured patients: An Eastern Association for Surgery of Trauma multicenter trial.

Prehospital identification of the injured patient likely to require emergent care remains a challenge. End-tidal carbon dioxide (ETCO2) has been used in the prehospital setting to monitor respiratory physiology and confirmation of endotracheal tube placement. Low levels of ETCO2 have been demonstrated to correlate with injury severity and mortality in a number of in-hospital studies. We hypothesized that prehospital ETCO2 values would be predictive of mortality and need for massive transfusion (MT) in intubated patients. This was a retrospective multicenter trial with 24 participating centers. Prehospital, emergency department, and hospital values were collected. Receiver operating characteristic curves were created and compared. Massive transfusion defined as >10 U of blood in 6 hours or death in 6 hours with at least 1 U of blood transfused. A total of 1,324 patients were enrolled. ETCO2 (area under the receiver operating characteristic curve [AUROC], 0.67; confidence interval [CI], 0.63-0.71) was better in predicting mortality than shock index (SI) (AUROC, 0.55; CI, 0.50-0.60) and systolic blood pressure (SBP) (AUROC, 0.58; CI, 0.53-0.62) (p < 0.0005). Prehospital lowest ETCO2 (AUROC, 0.69; CI, 0.64-0.75), SBP (AUROC, 0.75; CI, 0.70-0.81), and SI (AUROC, 0.74; CI, 0.68-0.79) were all predictive of MT. Analysis of patients with normotension demonstrated lowest prehospital ETCO2 (AUROC, 0.66; CI, 0.61-0.71), which was more predictive of mortality than SBP (AUROC, 0.52; CI, 0.47-0.58) or SI (AUROC, 0.56; CI, 0.50-0.62) (p < 0.001). Lowest prehospital ETCO2 (AUROC, 0.75; CI, 0.65-0.84), SBP (AUROC, 0.63; CI, 0.54-0.74), and SI (AUROC, 0.64; CI, 0.54-0.75) were predictive of MT in normotensive patients. ETCO2 cutoff for MT was 26 mm Hg. The positive predictive value was 16.1%, and negative predictive value was high at 98.1%. Prehospital ETCO2 is predictive of mortality and MT. ETCO2 outperformed traditional measures such as SBP and SI in the prediction of mortality. ETCO2 may outperform traditional measures in predicting need for transfusion in occult shock. Diagnostic test, level III.

A STUDY ON CORRELATION BETWEEN MODIFIED SHOCK INDEX AND SERUM LACTATE VALUES

INTRODUCTION: The Modied Shock Index is a test to identify occult shock in a patient with a normal blood pressure. High Lactate levels have been validated to identify the degree of shock and also response to resuscitation. The shock index (SI) is a bedside assessment dened as heart rate divided by systolic blood pressure, with a normal range of 0.5 to 0.7 in healthy adults. METHODOLOGY: Demographic data like age and sex was obtained. The patients were evaluated clinically, history and hemodynamic were noted. ABG was done on the patients and lactate levels were recorded. Requirement of Inotropic support, mechanical ventilation and dialysis were noted. All the ndings were recorded on a predesigned and prepared proforma. The Modied Shoc RESULTS: k Index was split into three categories: &lt;0.7, 0.7-1.3 and &gt;1.3. The mean lactate in the &lt;0.7 group, 0.7-1.3 group and the &gt;1.3 group were 5.5000, 3.7060 and 4.8616 respectively. A Tukey post hoc test revealed that patients with modie CONCLUSION: d Shock Index &gt;1.3 had statistically signicantly higher Lactate levels (5.729±2.846, p = 0.000) than patients with modied Shock Index 0.7 – 1.3 (3.706±1.520).

Signs of post-traumatic hypovolemia on abdominal CT and their clinical importance: A systematic review

PurposeOur aim was to assess the findings of hypovolemia on abdominal CT that are most frequently seen in blunt abdominal trauma patients. When possible, we assessed the correlation of these CT signs with clinical outcome. MethodsMEDLINE, CENTRAL and EMBASE were systematically searched. Two reviewers independently screened and included articles and performed the data-extraction. Primary outcomes of interest were the frequency of each sign and its correlation with mortality. Secondary outcomes were need for intervention, transfusion need, intensive care unit admission rate and length of stay. ResultsA flat inferior vena cava and an inferior vena cava halo, a diminished aortic calibre, shock bowel, altered enhancement of the liver, pancreas, adrenals, kidneys, spleen and gallbladder, peripancreatic fluid and splenic volume changes have been described in the setting of hypovolemic trauma patients to constellate a CT hypovolemic shock complex. It is argued that vascular signs represent the true hypovolemic state and the visceral signs represent hypoperfusion. There is no consensus on the frequency or clinical relevance of these signs, which at least partly can be explained by the heterogeneity in study design, study population, scanning protocols and outcome parameters. Available evidence suggests a good predictive value for occult shock and a higher mortality rate when a flat inferior vena cava is present. Evidence regarding the other signs is scarce. ConclusionsThe hypovolemic shock complex is an entity of both vascular and visceral CT signs that can be seen in blunt trauma patients. It can offer guidance to a swift primary imaging survey in the acute trauma setting, allowing the radiologist to alert the treating physicians to possible pending hypovolemic shock.

Atypical presentation of hemorrhagic shock in pregnancy: a case highlighting the developing field of emergency medicine in Israel

BackgroundOccult hemorrhagic shock secondary to uterine rupture represents a true obstetric emergency and can result in significant morbidity and mortality for both the patient and the fetus. Multiparity and prior cesarean sections are known risk factors. Typically, these patients present late in gestation, often secondary to the physiologic stresses on the uterus related to contractions. This pathology is less common earlier in pregnancy and can often be overlooked in the acute setting.Case presentationWe present the case of a 31-year-old female with three prior gestations, two parities and two prior cesarean sections, resulting in three live births, who presented to the Emergency Department (ED) 22-weeks pregnant with acute onset dyspnea and an episode of syncope. Due to her altered mental status there was concern for occult shock, despite normal vital signs. Large amounts of free fluid in the abdomen were noted on bedside ultrasonography with a high suspicion for uterine pathology. She was resuscitated with blood and taken immediately to the operating room for surgical management where she was found to have had a uterine rupture.ConclusionThis case highlights a rare presentation of a well-known obstetric emergency, due to the patient’s development of uterine rupture early in gestation. Consequently, emergency physicians should consider atraumatic hypovolemic shock, secondary to this obstetric catastrophe, even at a stage that far precedes its expected presentation. In addition, we make note of how this case validated our department’s integrated emergency medicine model, the first in the State of Israel.

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

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

Respiratory adjusted shock index for identifying occult shock and level of Care in Sepsis Patients

ObjectiveEarly identification of shock allows for timely resuscitation. Previous studies note the utility of bedside calculations such as the shock index (SI) and quick sepsis-related organ failure assessment (qSOFA) to detect occult shock. Respiratory rate may also be an important marker of occult shock. The goal of our study was to evaluate whether using a modified SI with respiratory rate would improve identification of emergency department sepsis patients admitted to an ICU or stepdown unit. MethodsA prospective, observational cohort study of the respiratory adjusted shock index (RASI), defined as HR/SBP × RR/10, was conducted. RASI was calculated from triage vital signs and compared to serum lactate. Primary outcome was admission to a higher level of care defined as ICU or stepdown unit. A multivariable logistic regression model including RASI, SI, lactate, age and sex was performed with disposition as the outcome variable. Areas under the curve (AUC) were calculated to detect occult shock and level of care for RASI, SI, and qSOFA. Results408 patients were enrolled, 360 were included in the analysis. Regression analysis revealed that lactate (OR 1.55, z = 4.38, p < 0.0001) and RASI (OR 2.27, z = 3.03, p < 0.002) were predictive of need for higher level of care. The AUC for RASI, SI, and qSOFA to detect occult shock were 0.71, 0.6, and 0.61 respectively. RASI also had a significant AUC in predicting level of care at 0.75 compared to SI (0.64) and qSOFA (0.62). ConclusionsRASI may have utility as a rapid bedside tool for predicting critical illness in sepsis patients.

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

The shock index (SI), calculated as hear rate/systolic blood pressure, is a simple hemodynamic marker that may be used to assess for the presence of occult shock in trauma patients. The normal range for a healthy adult patient is 0.5 to 0.7. Recently, studies have demonstrated that tachypnea is the most important predictor of cardiac arrest in hospital wards and is an important indicator of derangements across multiple organ systems. As such, we have sought to determine whether the inclusion of the patient's respiratory rate (RR) to the already existing SI (called the Respiratory Adjusted Shock Index [RASI]), calculated as hear rate/systolic blood pressure*(RR/10), will improve the overall diagnostic accuracy of detecting patients in early occult shock. A retrospective chart review over a 4-year period (2012-2016) at an urban, Level I trauma center was performed. All patients admitted to hospital for trauma were included in the study. Exclusion criteria were patients in traumatic arrest or in overt shock. Charts were reviewed for triage vital signs and point of care lactate drawn within 30 minutes of presentation. A lactate greater than 2 mmol/L was used to determine presence of hypoperfusion. The upper limit of normal for the RASI was calculated by multiplying the upper limit of the SI by 1.9 (RR of 19 divided by 10) and validated internally. A total of 3,093 patients were included in this study. There was no difference in SI for patients discharged versus patients admitted, 0.6 (95% CI, 0.5-0.7) versus 0.7 (95% CI, 0.5-0.8) and a significant difference between the same groups of patients (discharged vs. admitted) for the RASI, 1.1 (95% CI, 1.04-1.18) versus 1.46 (95% CI, 1.35-1.55), respectively. Area under the curve for SI was 0.58 and for the RASI score was 0.94. The RASI score improves diagnostic accuracy for detecting early occult shock in trauma patients when compared to the SI. Diagnostic, level II.

Lactate and microcirculation as suitable targets for hemodynamic optimization in resuscitation of circulatory shock.

A discussion of recent research exploring the feasibility of perfusion-guided resuscitation of acute circulatory failure with a focus on lactate and microcirculation. Upon diagnosis of shock, hyperlactemia is associated with poor outcome and, under appropriate clinical circumstances, may reflect inadequate tissue perfusion. Persistent hyperlactemia despite resuscitation is even more strongly correlated with morbidity and mortality. Importantly, there is minimal coherence between lactate trends and static hemodynamic measures such as blood pressure, especially after the initial, hypovolemic phase of shock. During this early period, lactate guided-resuscitation is effective and possibly superior to hemodynamic-guided resuscitation. Similar to hyperlactemia, impaired microcirculation is ubiquitous in shock and is evident even in the setting of hemodynamic compensation (i.e., occult shock). Moreover, persistent microcirculatory derangement is associated with poor outcome and may reflect ongoing shock and/or long-lasting damage. Although the wait continues for a microcirculation-guided resuscitation trial, there is progress toward this goal. Although questions remain, a multimodal perfusion-based approach to resuscitation is emerging with lactate and microcirculation as core measures. In this model, hyperlactemia and microcirculatory derangement support the diagnosis of shock, may help guide resuscitation during the initial period, and may reflect resuscitation efficacy and iatrogenic harm (e.g., fluid overload).

A systematic review of human and veterinary applications of noninvasive tissue oxygen monitoring.

To describe the methodology for and utilization of tissue oxygen monitoring by near infrared spectroscopy, and to review the current literature on the use of this monitoring modality in human and veterinary settings. Scientific reviews and original research found using the PubMed and CAB Abstract search engines with the following keywords: "tissue oxygen monitoring," "near-infrared tissue spectroscopy," and "tissue oxygen saturation (StO2 )." Tissue oxygen monitors have been evaluated in a wide variety of human clinical applications including trauma and triage, surgery, sepsis, and septic shock, and early goal-directed therapy. StO2 more rapidly identifies occult shock in human patients compared to traditional methods, which can lead to earlier intervention in these patients. Veterinary studies involving tissue oxygen monitoring are limited, but the technology may have utility for identification of hemorrhagic shock earlier than changes in base excess, blood lactate concentration, or other traditional perfusion parameters. Tissue oxygen monitoring is most commonly performed utilizing a noninvasive, portable monitor, which provides real-time, continuous, repeatable StO2 measurements. A decline in StO2 is an early indicator of shock in both human and veterinary patients. Low StO2 values in human patients are associated with increased morbidity, mortality, and length of hospitalization, as well as the development of multiple organ system dysfunction and surgical site infections.

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

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

Evaluation of StO2 tissue perfusion monitoring as a tool to predict the need for lifesaving interventions in trauma patients

BackgroundHemorrhage remains the leading cause of mortality in preventable trauma deaths. Earlier recognition of hemorrhagic shock decreases the time to implementation of life-saving interventions improves patient survival. The presence of hemorrhagic shock is not always apparent using standard vital signs monitoring, a clinical state referred to as occult shock. MethodsThis prospective, observational study was performed at Memorial Hermann Hospital in Houston, TX. Prisoners, pregnant women, and patients with burn injuries greater than 20% total body surface area or bilateral upper extremity fractures were excluded. Hutchinson Technologies Spot Check StO2 device was used to measure StO2 values. ResultsStO2 values less than 75% were predictive of the need for blood product transfusions (P < .01) and the need for emergency surgeries. Nearly one-third of patients who presented with a systolic blood pressure 120 mm Hg or more presented with StO2 less than 75% and had a median base deficit of 5 (3 to 6.5). ConclusionsAdmission StO2 measurements less than 75% predict the need for blood products and emergent surgical procedures and may be used as an adjunct method for identifying shock. StO2 measurements can aid where laboratory values are unavailable.

347 Detecting Occult Shock in Trauma Patients: A Comparison of Serum Lactate versus Shock Index

347 Detecting Occult Shock in Trauma Patients: A Comparison of Serum Lactate versus Shock Index

Comparing biomarkers of traumatic shock: the utility of anion gap, base excess, and serum lactate in the ED

BackgroundBiomarkers such as serum lactate, anion gap (AG), and base excess (BE) have been shown to be of use in determining shock in patients with seemingly normal vital signs. We seek to determine if these biomarkers can be used interchangeably in patients with trauma in the emergency setting based on their test characteristics and correlation to each other. MethodsA prospective observational cohort study was undertaken at an urban level 1 trauma center. Baseline vital signs, point-of-care BE, AG, and serum lactate were recorded in all patients who presented for trauma. Correlation was determined by linear regression model. Overall test characteristics and relative risk were calculated. ResultsOne hundred patients were enrolled. The median age was 30 years (interquartile range, 24-42 years), and 89% were male. Fifty-three percent of injuries were blunt trauma. Pearson correlation of serum lactate to BE was −0.81 (r2 = 0.66; 95% confidence interval [CI], 0.53-0.75; P < .001), that of BE to AG was −0.71 (r2 = 0.5; 95% CI, −0.80 to −0.57; P < .01), and that for serum lactate to AG was 0.71 (r2 = 0.5; 95% CI, 0.57-0.80; P < .01). ConclusionsThis study demonstrates that the biomarkers have similar test characteristics which may make them interchangeable as indicators for the presence of occult shock in patients with trauma. Lactate and BE correlate well with each other; however, AG was not as strongly correlated with either.

Inferior Vena Cava Size is Not Associated With Shock Following Injury: Radomski M, Ritesh A, Knapp S, et al. J Trauma Acute Care Surg 2014;77:34−9.

The objective of this retrospective cohort study was to determine if inferior vena cava (IVC) size on computed tomographic (CT) scan after traumatic injury is associated with clinically occult shock.

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

BackgroundIdentification 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 methodsWe 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). ResultsTwo 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. ConclusionsA 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.

Venous and arterial base deficits

Trauma centers are increasingly advocating the replacement of arterial blood gas measurements with venous blood gas measurements for simplification of base deficit (BD) determination. These values have never been demonstrated to agree in important trauma populations, such as for patients in occult shock (OS) or the elderly. The goal of this study was to investigate the level of agreement between venous and arterial BDs from blood gases in critically ill or injured patients, specifically in OS and the elderly. This is a retrospective, consecutive, cohort study using matched pairs of venous and arterial blood gases from patients admitted to the Trauma and Neurosurgery Intensive Care Unit in a Level I trauma center in Toronto, Ontario, Canada. Agreement between near simultaneous arterial and venous BD was calculated using the Bland-Altman method. McNemar's test was used for differences in BDs in the presence or absence of OS and in elderly patients. BDs for 466 arterial and venous samples from 72 patients were compared pairwise. There was no significant difference between samples (p = 0.88). Ninety-eight percent of samples were within 3.0 mmol/L of each other. No significant differences were detected between venous and arterial BD in the presence of OS or in the elderly (p = 0.72 and p = 0.25, respectively). Arterial and venous BDs agree, including in the presence of OS and in the elderly. Consideration may be given to venous sampling both in the intensive care unit or in other areas of care, such as the trauma bay. Diagnostic study, level III.