Initial inferior vena cava diameter on computed tomographic scan independently predicts mortality in severely injured trauma patients. J Trauma Acute Care Surg. 2013;74:741-745; discussion 741-745. [PMID: 23425730 DOI: 10.1097/ta.0b013e3182827270]

Hematocrit and lactate trends help predict outcomes in trauma independent of CT and other clinical parameters

Background

Hematocrit and lactate have an established role in trauma as indicators of bleeding and cell death, respectively. The wide availability of CT imaging and clinical data poses the question of how these can be used in combination to predict outcomes.

Purpose

To assess the utility of hematocrit or lactate trends in predicting intensive care unit (ICU) admission and hospital length of stay (LOS) in patients with torso trauma combined with clinical parameters and injury findings on CT.

Materials and Methods

This was a single-center retrospective study of adults with torso trauma in one year. Trends were defined as a unit change per hour. CT findings and clinical parameters were explanatory variables. Outcomes were ICU admission and hospital LOS. Multivariate logistic and negative binomial regression models were used to calculate the odds ratio (OR) and incident rate ratio (IRR).

Results

Among 840 patients, 561 (72% males, age 39 ± 18) were included, and 168 patients (30%) were admitted to the ICU. Decreasing hematocrit trend [OR 2.54 (1.41-4.58), p = 0.002] and increasing lactate trend [OR 3.85 (1.35-11.01), p = 0.012] were associated with increased odds of ICU admission. LOS median was 2 (IQR: 1-5) days. Decreasing hematocrit trend [IRR 1.37 (1.13-1.66), p = 0.002] and increasing lactate trend [2.02 (1.43-2.85), p < 0.001] were associated with longer hospital LOS.

Conclusion

Hematocrit and lactate trends may be helpful in predicting ICU admission and LOS in torso trauma independent of organ injuries on CT, age, or admission clinical parameters.

Multidetector CT Imaging Biomarkers as Predictors of Prognosis in Shock: Updates and Future Directions

A severe mismatch between the supply and demand of oxygen is the common sequela of all types of shock, which present a mortality of up to 80%. Various organs play a protective role in shock and contribute to whole-body homeostasis. The ever-increasing number of multidetector CT examinations in severely ill and sometimes unstable patients leads to more frequently encountered findings leading to imminent death, together called "hypovolemic shock complex". Features on CT include dense opacification of the right heart and major systemic veins, venous layering of contrast material and blood, densely opacified parenchyma in the right hepatic lobe, decreased enhancement of the abdominal organ, a dense pulmonary artery, contrast pooling in dependent lungs, and contrast stasis in pulmonary veins. These findings are biomarkers and prognostic indicators of paramount importance which stratify risk and improve patient outcomes. In this review, we illustrate the various CT patterns in shock and review the spectrum and prognostic significance of thoraco-abdominal vascular and visceral alarming signs of impending death with the intention of increasing awareness among radiologists and radiographers to prepare for immediate resuscitation when required.

Evaluation of caudal vena cava size using computed tomography in dogs under general anesthesia

This study investigated the association between caudal vena cava (CVC) size and circulatory dynamics in dogs using computed tomography (CT) under general anesthesia. The subjects were 104 dogs who had undergone CT under general anesthesia in the past. The ratio of short diameter of the CVC to aortic diameter (CVC_S/Ao) and the ratio of long to short diameter of the CVC (CVC_L/CVC_S) in the thorax and abdomen, respectively, were calculated using factors such as mean blood pressure (MBP), shock index (SI), anemia, hypoproteinemia, presence of intra-abdominal mass, and cardiac disease. There was a significant but negligible negative correlation between CVC_S/Ao and MBP. In contrast, no significant correlation was found between CVC size and SI. The low MBP group had significantly higher CVC_S/Ao of the thorax than the normal MBP group. The group with intra-abdominal mass had significantly lower CVC_S/Ao of the abdomen than the group without intra-abdominal mass. The group with cardiac disease had significantly lower CVC_L/CVC_S of the thorax than the group without cardiac disease. In multiple regression analysis, low MBP, cardiac disease, intra-abdominal mass, and anemia were significant factors for CVC_S/Ao of the thorax, CVC_L/CVC_S of the thorax, CVC_S/Ao of the abdomen, and CVC_L/CVC_S of the abdomen, respectively. In conclusion, CVC size assessment using CT in dogs under general anesthesia is influenced by various factors.

Flat Inferior Vena Cava on Computed Tomography for Predicting Shock and Mortality in Trauma: A Meta-Analysis

Hypovolemia may be underestimated due to compensatory mechanisms. In this systematic review and meta-analysis, we investigated the diagnostic accuracy of a flat inferior vena cava (IVC) on computed tomography (CT) for predicting the development of shock and mortality in trauma patients. Relevant studies were obtained by searching PubMed, EMBASE, and Cochrane databases (articles up to 16 September 2022). The number of 2-by-2 contingency tables for the index test were collected. We adopted the Bayesian bivariate random-effects meta-analysis model. Twelve studies comprising a total of 1706 patients were included. The flat IVC on CT showed 0.46 pooled sensitivity (95% credible interval [CrI] 0.32-0.63), 0.87 pooled specificity (95% CrI 0.78-0.94), and 0.78 pooled AUC (95% CrI 0.58-0.93) for the development of shock. The flat IVC for mortality showed 0.48 pooled sensitivity (95% CrI 0.21-0.94), 0.70 pooled specificity (95% CrI 0.47-0.88), and 0.60 pooled AUC (95% CrI 0.26-0.89). Regarding the development of shock, flat IVC provided acceptable accuracy with high specificity. Regarding in-hospital mortality, the flat IVC showed poor accuracy. However, these results should be interpreted with caution due to the high risk of bias and substantial heterogeneity in some included studies.

Initial assessment of hemorrhagic shock by trauma computed tomography measurement of the inferior vena cava in blunt trauma patients

Purpose: Inferior vena cava (IVC) collapse is related to hypovolemia. Sonography has been used to measure the IVC diameter, but there is variation depending on the skill of the operator and it is difficult to obtain accurate measurements in patients who have a large amount of intestinal gas or are obese. As a modality to obtain accurate measurements, we measured the diameters of the IVC and aorta on trauma computed tomography scans and investigated the correlation between the IVC to aorta ratio and the shock index in blunt trauma patients.Methods: We retrospectively analyzed the medical records of 588 trauma patients who were transferred to the regional trauma center (level 1) of Wonkang University hospital from March 2020 to February 2021. We included trauma patients 18 years or older who met the trauma activation criteria and underwent trauma computed tomography scans with intravenous contrast within 40 minutes of admission. The shock index was calculated from vital signs before trauma computed tomography scan, and measurements of the anteroposterior diameter of the IVC (AP), the transverse diameter of the IVC (T), and aorta were made 10 mm above the right renal vein in the venous phase.Results: Overall, 271 patients were included in this study, of whom 150 had a shock index ≤0.7 and 121 had a shock index >0.7. The T to AP ratio and AP to aorta ratio were significantly different between groups. Cutoffs were identified for the T to AP ratio and AP to aorta ratio (2.37 and 0.62, respectively) that produced clinically useful sensitivity and specificity for predicting a shock index >0.7, demonstrating moderate accuracy (T to AP ratio: area under the curve, 0.71; sensitivity, 59%; specificity, 87% and AP to aorta ratio: area under the curve, 0.70; sensitivity, 55%; specificity, 91%).Conclusions: The T to AP ratio and AP to aorta ratio are useful for predicting hemorrhagic shock in trauma patients.

Association of inferior vena cava diameter ratio with outcomes in patients with gastrointestinal bleeding

Objective

To examine the association of inferior vena cava (IVC) diameter ratio measured using computed tomography with outcomes in patients with gastrointestinal bleeding (GIB).

Methods

A single-center retrospective observational study was conducted on consecutive patients with GIB who presented to the emergency department. The IVC diameter ratio was calculated by dividing the maximum transverse and anteroposterior diameters perpendicular to it. The association of the IVC diameter ratio with outcomes was examined using multivariable logistic regression analysis. The primary outcome was in-hospital mortality. The area under the receiver operator characteristic curve (AUC) of the IVC diameter ratio was calculated, and the sensitivity and specificity, including the cutoff values, were computed.

Results

In total, 585 patients were included in the final analysis. The in-hospital mortality rate was 4.6% (n=27). The IVC diameter ratio was significantly associated with higher in-hospital mortality in multivariable logistic regression analysis (odds ratio, 1.793; 95% confidence interval [CI], 1.239–2.597; P=0.002). The AUC of the IVC diameter ratio for in-hospital mortality was 0.616 (95% CI, 0.498–0.735). With a cutoff of the IVC diameter ratio (≥2.1), the sensitivity and specificity for predicting in-hospital mortality were 44% (95% CI, 26%–65%) and 71% (95% CI, 67%–75%), respectively.

Conclusion

The IVC diameter ratio was independently associated with in-hospital mortality in patients with GIB. However, the AUC of the IVC diameter ratio for in-hospital mortality was low.

The Flatness Index of Inferior Vena Cava can be an Accurate Predictor for Hypovolemia in Multi-Trauma Patients

INTRODUCTION

Shock is the leading cause of death in multi-trauma patients and must be detected at an early stage to improve prognosis. Many parameters are used to predict clinical condition and outcome in trauma. Computed tomography (CT) signs of hypovolemic shock in trauma patients are not clear yet, requiring further research. The flatness index of inferior vena cava (IVC) is a helpful method for this purpose.

METHODS

This is a prospective, cross-sectional study which included adult multi-trauma patients (>18 years) who were admitted to the emergency department (ED) and underwent a thoraco-abdominal CT from 2017 through 2018. The main objective of this study was to investigate whether the flatness index of IVC can be used to determine the hypovolemic shock at an early stage in multi-trauma patients, and to establish its relations with shock parameters. The patients' demographic features, trauma mechanisms, vitals, laboratory values, shock parameters, and clinical outcome within 24 hours of admission were recorded.

RESULTS

Total of 327 (229 males with an average age of 40.9 [SD = 7.93]) patients were included in the study. There was no significant difference in the flatness index of IVC within genders (P = .134) and trauma mechanisms (P = .701); however, the flatness index of IVC was significantly higher in hypotensive (systolic blood pressure [SBP] ≤90 mmHg and/or diastolic blood pressure [DBP] ≤60 mmHg; P = .015 and P = .019), tachycardic (P = .049), and hypoxic (SpO2 ≤%94; P <.001) patients. The flatness index of IVC was also higher in patients with lactate ≥ 2mmol/l (P = .043) and patients with Class III hemorrhage (P = .003). A positive correlation was determined between lactate level and the flatness index of IVC; a negative correlation was found between Glasgow Coma Scale (GCS) and Revised Trauma Score (RTS) with the flatness index of IVC (for each of them, P <.05).

CONCLUSION

The flatness index of IVC may be a useful method to determine the hypovolemic shock at an early stage in multi-trauma patients.

A Flat Inferior Vena Cava on Computed Tomography Is Associated With Worse Outcomes in Emergency General Surgery

BACKGROUND

Several trauma studies have shown that a "flat" inferior vena cava (IVC) is associated with poor clinical outcomes, including hypovolemic shock, major bleeding, transfusions and mortality. These studies utilize IVC measurements on computed tomography (CT) scans, and rarely include emergency general surgery patients. We examine the association between IVC flatness and clinical outcomes in a series of patients with perforated viscus.

MATERIALS AND METHODS

Medical records at an academic hospital were reviewed of adults with perforated viscus. Patients who underwent laparotomy or laparoscopy were included if they underwent CT within 12 h prior to incision time. Perforated appendicitis was excluded. A ratio was calculated of the transverse to anterior-posterior diameter of the IVC at 3 locations, then averaged. Clinical outcomes were analyzed by the average IVC ratio.

RESULTS

A total of 83 patients were included. Using binomial regression, the average IVC ratio significantly correlated with ICU admission (OR 3.6, 95% CI 1.2 to 11) and acute kidney injury (OR 2.3, 95% CI 1.0 to 5.3), but not postoperative shock (OR 1.2, 95% CI 0.56 to 2.6).

CONCLUSIONS

A flat IVC on CT prior to an operation for perforated viscus was associated with worse outcomes, including increased rate of ICU admission and acute kidney injury. More outcomes research is needed to assess the potential role of IVC assessment in preoperative resuscitation.

Association of inferior vena cava diameter ratio measured on computed tomography scans with the outcome of patients with septic shock

The collapsibility and diameter of the inferior vena cava (IVC) are known to predict the volume state in critically ill patients. However, no study has examined the prognostic value of the IVC diameter ratio measured on computed tomography (CT) in patients with septic shock. A retrospective observational study was conducted on adult septic shock patients visiting the emergency department at a university hospital in Korea. The IVC diameter ratio was calculated by dividing the maximal transverse and anteroposterior diameters. Multivariable logistic regression analysis was conducted to investigate whether the IVC diameter ratio predicted in-hospital mortality. The area under the curve (AUC) was calculated, and the sensitivity, specificity, positive predictive value, and negative predictive value with the cut-off values were computed. A total of 423 adult septic shock patients were included, and the in-hospital mortality rate was 17%. The median IVC diameter ratio in non-survivors was significantly greater than in survivors (1.56 cm vs 1.4 cm, P = .004). The IVC diameter ratio was found to be significantly associated with in-hospital mortality on multivariate logistic regression analysis after adjustment for confounding variables (odds ratio = 1.48, confidence interval: 1.097-1.998, P = 0.01). The AUC for IVC diameter ratio was 0.607. A cut-off IVC diameter ratio of ≥1.31 cm had 75% sensitivity and 42% specificity for predicting in-hospital mortality. The IVC diameter ratio measured on CT may to be helpful in predicting the prognosis of septic shock patients. However, due to its low diagnostic performance and sensitivity, further research is warranted.

Higher enhanced computed tomography attenuation value of the aorta is a predictor of massive transfusion in blunt trauma patients

Objective

Several scoring systems have been developed to identify patients who require massive transfusion (MT) after major trauma to improve survival. The primary goal of this study was to investigate the usefulness of enhanced computed tomography attenuation values (CTAVs) of major vessels to determine the need for MT in patients with major blunt trauma.

Methods

This single-center retrospective cohort study evaluated patients aged 16 years or older who underwent contrast-enhanced computed tomography scan of the torso after major blunt trauma. The CTAVs of six major vessel points in both the arterial and portal venous phases at initial computed tomography examination were assessed and compared between the MT and the no MT group. The capability of enhanced CTAVs to predict the necessity for MT was estimated based on the area under the receiver operating characteristic curve.

Results

Of the 254 eligible patients, 36 (14%) were in the MT group. Patients in the MT group had significantly higher CTAVs at all sites except the inferior vena cava in both the arterial and portal venous phases than that in the no MT group. The descending aorta in the arterial phase had the highest accuracy for predicting MT, with an AUROC of 0.901 (95% confidence interval, 0.855 to 0.947; P<0.001).

Conclusion

Initial elevation of enhanced CTAV of the aorta is a predictor for the need for MT. A higher CTAV of the aorta should alert the trauma surgeon or emergency physician to activate their MT protocol.

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.

The association between the initial lactate level and need for massive transfusion in severe trauma patients with and without traumatic brain injury

Background

Exsanguination is a major cause of death in severe trauma patients. The purpose of this study was to analyze the prognostic impact of the initial lactate level for massive transfusion (MT) in severe trauma. We divided patients according to subgroups of traumatic brain injury (TBI) and non-TBI.

Methods

This single-institution retrospective study was conducted on patients who were admitted to hospital for severe trauma between January 2016 and December 2017. TBI was defined by a head Abbreviated Injury Scale ≥3. Receiver operating characteristic analysis was used to analyze the prognostic impact of the lactate level. Multivariate analyses were performed to evaluate the relationship between the MT and lactate level. The primary outcome was MT.

Results

Of the 553 patients, MT was performed in 62 patients (11.2%). The area under the curve (AUC) for the lactate level for predicting MT was 0.779 (95% confidence interval [CI], 0.742 to 0.813). The AUCs for lactate level in the TBI and non-TBI patients were 0.690 (95% CI, 0.627 to 0.747) and 0.842 (95% CI, 0.796 to 0.881), respectively. In multivariate analyses, the lactate level was independently associated with the MT (odds ratio [OR], 1.179; 95% CI, 1.070 to 1.299). The lactate level was independently associated with MT in non-TBI patients (OR, 1.469; 95% CI, 1.262 to 1.710), but not in TBI patients.

Conclusions

The initial lactate level may be a possible prognostic factor for MT in severe trauma. In TBI patients, however, the initial lactate level was not suitable for predicting MT.

The inferior vena cava: a pictorial review of embryology, anatomy, pathology, and interventions

The inferior vena cava (IVC) is the largest venous conduit below the diaphragm. Although this structure is often overlooked both clinically and radiographically, it can be involved in many different pathologic processes. A thorough understanding of the IVC will assist the radiologist in recognizing anatomic variants, identifying abnormalities, and providing accurate differential diagnoses. In this comprehensive pictorial review of the IVC, we depict embryology behind anatomic variants, present a wide range of pathology with a focus on diagnostic imaging, and describe relevant endovascular interventions.

Size and shape of the inferior vena cava before and after a fluid challenge: a pilot study

BACKGROUND

Recent meta-analyses failed to support the reliability of ultrasound assessment of the inferior vena cava (IVC) to predict fluid responsiveness. However, the techniques utilized were heterogeneous. We hypothesized that the variability of the elliptic section and caliber of the IVC along its course may influence ultrasound evaluation. Therefore, we investigated IVC size and shape at four levels, before and after a fluid challenge.

METHODS

Twenty mechanically-ventilated adult patients who received a fluid challenge after cardiac surgery were enrolled. They were regarded as responders if the cardiac index increased more than 15%. Before and after the fluid challenge, IVC anteroposterior (AP) and lateral (LA) diameters, the flat ratio, and the distensibility index were assessed by ultrasound just above the iliac veins, at the confluence of the renal veins, before the confluence of the hepatic veins (where blood flow velocity was also measured), and after it.

RESULTS

At all levels, IVC section was elliptical, so that IVC diameters varied between a minimum and a maximum according to the measurement angle. Such interval increased in correspondence of the renal veins, where IVC section was more eccentric. The distensibility index was higher when assessed on AP diameters. After the fluid challenge, non-responders showed a diffuse increase of AP diameters, whereas responders showed an increase of blood velocity before the confluence of the hepatic veins.

CONCLUSIONS

The elliptic section should be considered when assessing IVC size. AP diameters are shorter and more affected by the respiratory cycle. After a fluid challenge, an increase of blood velocity associated with unchanged AP diameters may suggest fluid responsiveness.

Initial inferior vena cava diameter predicts massive transfusion requirements in blunt trauma patients: A retrospective cohort study

OBJECTIVES

The inferior vena cava (IVC) diameter is associated with shock and increased mortality in trauma patients. However, there are no reports examining the association between the IVC diameter and massive transfusion (MT) requirements in trauma patients. The aim of this study was to evaluate the association between IVC diameter and MT requirements in patients with blunt trauma.

METHODS

We retrospectively reviewed all patients who were consecutively hospitalized with blunt trauma (Injury Severity Score [ISS] ≥16) between from November 1, 2011 to March 30, 2016. Univariate and multivariate analyzes were performed to identify the independent predictors of MT (defined as >10units of red cell concentrate transfusions within 24h of admission). Receiver operating characteristic curve and the area under the curve (AUC) were estimated.

RESULTS

Of the 222 patients included in this study, MT occurred in 22.5% patients. On multiple regression analysis, IVC diameter [Odds ratio (OR), 0.88; 95% confidence interval (CI), 0.80-0.96; p<0.01], fibrin degradation product (FDP; OR, 1.01; 95% CI, 1.00-1.01; p<0.01), and fibrinogen level (OR, 0.99; 95% CI, 0.98-1.00; p<0.01) were strong predictors of MT. IVC diameter demonstrated moderate accuracy (AUC, 0.74; cutoff level, 13.0mm; sensitivity, 67%; specificity, 73%). Combined cutoff levels of FDP <80.5μg/ml, fibrinogen ≥165mg/dl, and IVC diameter ≥13mm could also determine how unnecessary a MT was with 100% accuracy.

CONCLUSIONS

Initial IVC diameter is a predictor of MT in blunt trauma patients.

Contrast-Enhanced Computed Tomography in Intensive Care Unit Patients With Acute Clinical Deterioration: Impact of Hyperattenuating Adrenal Glands

PURPOSE

The study sought to assess the frequency and prognostic value of hyperattenuating adrenal glands on contrast-enhanced computed tomography (CT) scans of surgical intensive care unit (ICU) patients with acute clinical deterioration.

METHODS

Eighty-eight consecutive ICU patients (63.2 ± 14.5 years of age) were included in this retrospective analysis. All patients underwent biphasic contrast-enhanced CT due to an acute clinical deterioration. Hyperattenuation of the adrenal glands was assessed subjectively and objectively. Subjective presence or absence of hyperattenuating adrenal glands was assessed by 2 blinded radiologists (J.B. and R.S.L.) in consensus. Hounsfield units (HU) were measured in the adrenal glands and in the inferior vena cava. Objective hyperattenuation was defined as HU (adrenal glands) > HU (inferior vena cava) with a 15-HU threshold. Death within 14 days following CT was set as endpoint and acquired from electronic patient data.

RESULTS

Thirty-eight patients (43.2%, Group A_subj) exhibited hyperattenuation of the adrenal glands, whereas 50 patients (56.8%, Group B_subj) did not. Concerning the objective analysis, 31 patients (35.2%, Group A_obj) exhibited hyperdense adrenal glands, whereas 53 patients (64.8%, Group B_obj) did not. Overall 27 of 88 patients (30.6%) died within 14 days following the CT examination. Lethal outcome was significantly more frequent among patients in Group A_subj and A_obj (19 of 38 patients [50.0%] and 15 of 31 patients [48.4%]) as compared with patients in Group B_subj (8 of 50 patients [16.0%]) and Group B_obj (12 of 57 patients [21.1%]; P < .05). Subjective and objective analysis correlated significantly (P < .05).

CONCLUSIONS

Hyperattenuation of adrenal glands on contrast-enhanced CT of ICU patients with acute clinical deterioration is associated with a high mortality and might serve as a prognostic marker for patients' outcome.

Echocardiographic Characterization of the Inferior Vena Cava in Trained and Untrained Females

The aim of the study was to explore the long- and short-axis dimensions, shape and collapsibility of the inferior vena cava in 46 trained and 48 untrained females (mean age: 21 ± 2 y). Echocardiography in the subcostal view revealed a larger expiratory long-axis diameter (mean: 24 ± 3 vs. 20 ± 3 mm, p < 0.001) and short-axis area (mean: 5.5 ± 1.5 vs. 4.7 ± 1.4 cm², p = 0.014) in trained females. IVC shape (the ratio of short-axis major to minor diameters) and the relative decrease in IVC dimension with inspiration were similar for the two groups. The IVC long-axis diameter reflected short-axis minor diameter and was correlated to maximal oxygen uptake (r = 0.52, p < 0.01). In summary, the results indicate that trained females have a larger IVC similar in shape and respiratory decrease in dimensions to that of untrained females. The long-axis diameter corresponded closely to short-axis minor diameter and, thus, underestimates maximal IVC diameter.

A snapshot of circulation failure following acute traumatic injury: The expansion of computed tomography beyond injury diagnosis

OBJECTIVE

CT scans with a flat Inferior Vena Cava (IVC) suggest hypovolemia, and the presence of shock bowel implies hypoperfusion. The purpose of this study is to correlate injury severity, resuscitation needs, and clinical outcomes with CT indices of hypovolemia and hypoperfusion.

DESIGN

Retrospective cohort study.

SETTING

Level II trauma centre in Central California.

PATIENTS

Adult patients imaged with abdominal and pelvic CT scans, from January 2010-January 2011.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Circulatory derangements on CT scans were defined as an IVC (AP) diameter measurement of <9 mm, flat IVC (FIVC), hypovolemia. The presence of small intestine hypoperfusion was shock bowel (SB). The absence of these findings was a normal CT scan (NCT). Comparisons of acid-base status, fluids, morbidity and mortality were made based on CT findings. Subgroups were: FIVC (n=20), FIVC+SB (n=19), SB (n=4) only versus normal CT scans, NCT (n=47).

RESULTS

Overall ISS was 19 (SD) 14. The lowest ISS was in NCT 14 (SD) 10 and there was an incremental increase in ISS based on circulatory derangements, p=0.001. ICU admission was lowest in NCT and highest in the presence of hyovolemia and hypoperfusion, p=0.03. Similarly ED crystalloid requirements and the activation of a massive transfusion protocol (MTP), was lowest in NCT group and gradually increased significantly as hypovolemia and hypoperfusion was demonstrated on CT scans. Additional parameters such as metabolic acidosis, nosocomial infections and mortality were associated with acute CT findings of circulatory failure.

CONCLUSIONS

Hypovolemia and hypoperfusion, markers of abnormal circulation, were demonstrated on CT scans for trauma evaluation. The presence of these findings alone or in combination showed strong correlation with high injury severity, and the need for aggressive resuscitation.

Influence of breathing movements and Valsalva maneuver on vena caval dynamics

AIM: To study changes produced within the inferior vena cava (IVC) during respiratory movements and identify their possible clinical implications.

METHODS: This study included 100 patients (46 women; 54 men) over 18 years of age who required an abdominal computed tomography (CT) and central venous access. IVC cross-sectional areas were measured on CT scans at three levels, suprarenal (SR), juxtarenal (JR) and infrarenal (IR), during neutral breathing and again during the Valsalva maneuver. All patients were instructed on how to perform a correct Valsalva maneuver. In order to reduce the total radiation dose in our patients, low-dose CT protocols were used in all patients. The venous blood pressure (systolic, diastolic and mean) was invasively measured at the same three levels with neutral breathing and the Valsalva maneuver during venous port implantation. From CT scans, three-dimensional models of the IVC were constructed and a collapsibility index was calculated for each patient. These data were then correlated with venous pressures and cross-sectional areas.

RESULTS: The mean patient age was 51.64 ± 12.01 years. The areas of the ellipse in neutral breathing were 394.49 ± 85.83 (SR), 380.10 ± 74.55 (JR), and 342.72 ± 49.77 mm² (IR), and 87.46 ± 18.35 (SR), 92.64 ± 15.36 (JR) and 70.05 ± 9.64 mm² (IR) during the Valsalva (Ps < 0.001). There was a correlation between areas in neutral breathing and in the Valsalva maneuver (P < 0.05 in all areas). Large areas decreased more than smaller areas. The collapsibility indices were 0.49 ± 0.06 (SR), 0.50 ± 0.04 (JR) and 0.50 ± 0.04 (IR), with no significant differences in any region. Reconstructed three-dimensional models showed a flattening of the IVC during Valsalva, adopting an ellipsoid cross-sectional shape. The mean pressures with neutral breathing were 9.44 ± 1.78 (SR), 9.40 ± 1.44 (JR) and 8.84 ± 1.03 mmHg (IR), and 81.08 ± 21.82 (SR), 79.88 ± 19.01 (JR) and 74.04 ± 16.56 mmHg (IR) during Valsalva (Ps < 0.001). There was a negative correlation between cross-sectional caval area and venous blood pressure, but this was not statistically significant in any of the cases. There was a significant correlation between diastolic and mean pressures measured during neutral breathing and in Valsalva.

CONCLUSION: Respiratory movements have a major influence on IVC dynamics. The increase in intracaval pressure during Valsalva results in a significant decrease in the IVC cross-sectional area.

Inferior vena cava size is not associated with shock following injury

BACKGROUND

The inferior vena cava (IVC) collapses with shock but may also be collapsed in volume-depleted patients in the absence of shock. The speed and availability of computed tomography (CT) make IVC measurement an attractive diagnostic modality for shock. The purpose of this study was to determine if IVC size following injury is associated with shock.

METHODS

Retrospective data were collected on 272 trauma patients admitted to an adult trauma center from January 1 to December 31, 2012. Patients who met the highest-level activation criteria and underwent an abdominal CT scan during their initial resuscitation were included. All images were reviewed by two attending radiologists, and concordance was assessed using the Pearson correlation coefficient. The transverse (T) and anteroposterior (AP) diameters of the IVC were measured to calculate a T/AP ratio. Analysis of variance and χ were used to assess for a relationship between this ratio and various indices of shock.

RESULTS

The mean (SD) age of the study cohort was 50 (21) years, mean (SD) Injury Severity Score (ISS) was 14 (9), 74% were male, and 96% sustained blunt trauma. The overall mean (SD) T/AP ratio was 1.81 (0.68). Patients with a shock index greater than 0.7 were significantly younger (43 [20] years vs. 55 [21] years, p < 0.0001), had a significantly lower mean arterial pressure (88 [15] mm Hg vs. 103 [18] mm Hg, p < 0.0001), and were more likely to be intubated (56% vs. 24%, p < 0.0001). However, IVC T/AP ratio was not significantly different among the cohort. Similarly, there was no association between IVC size and the need for urgent operation, angiography, emergent transfusion, hospital length of stay, or mortality.

CONCLUSION

The static degree of IVC collapse is not associated with shock following injury. Therefore, measurement of IVC size by CT scan for patients with a T/AP ratio between 1 and 3.5 is not clinically relevant and cannot be used to predict mortality, shock, or impending shock.

LEVEL OF EVIDENCE

Diagnostic test, level III.

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.