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

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.

CT signs of hypovolemic shock complex in patients with non-traumatic shock

PURPOSE

To assess the frequency of hypovolemic shock complex (HSC) signs on CT in patients who presented to the emergency department (ED) with undifferentiated non-traumatic shock. Secondary aim was to assess the correlation between HSC signs and all-cause mortality.

METHODS

This retrospective, single-center study included 100 patients who underwent contrast-enhanced thoraco-abdominal CT in the ED to evaluate the etiology for non-traumatic undifferentiated shock. All patients were retrospectively assigned a shock subtype (i.e., distributive, cardiogenic, hypovolemic, obstructive, multifactorial, and unknown) based on medical records. Patients' demographics and time to all-cause mortality up to 90 days were collected. All CT studies were re-assessed for the presence of HSC signs. Correlation between HSC signs, mortality and shock subtype was assessed.

RESULTS

Overall, 58% (58/100) of all patients had at least one HSC sign. Flattened inferior vena cava and adrenal hyper-enhancement were the most common HSC signs (27.3%, 27/99; in both). Overall mortality was 59% (59/100). When evaluated separately, shock liver was the only HSC sign to significantly correlate with increased mortality (84.6% vs. 55.2%, p = .04). However, patients with at least two HSC signs had a significantly higher mortality rate compared to patients without any HSC signs (73.5% vs. 45.2%, p = .017).

CONCLUSION

Most patients with non-traumatic shock had at least one HSC sign. Mortality rates were significantly higher in patients with two or more HSC signs compared to patients without any signs. Patients with shock liver sign had significantly higher mortality rates.

Inferior vena cava diameter on CT angiography predicts mesenteric angiography positive for extravasation in colonic diverticular bleeding

PURPOSE

Transcatheter arterial embolization (TAE) for colonic diverticular bleeding (CDB), an established procedure for hemostasis, is sometimes complicated by spontaneous hemostasis and unclear bleeding site on angiography despite active arterial bleeding on preoperative computed tomography angiography (CTA). Therefore, to investigate and increase the feasibility of TAE, this retrospective study evaluates the clinical and radiological features related to positive extravasation on angiography.

MATERIAL AND METHODS

Sixty CDB patients with extravasation on CTA underwent TAE between January 2011 and February 2021 and were divided into extravasation-positive (P-group; n = 25) and -negative groups (N-group; n = 35) based on the superior or inferior mesenteric angiography. Patient characteristics, laboratory findings, the diameter of the inferior vena cava (IVCD), the diameter of superior and inferior mesenteric veins, and technical outcomes were evaluated.

RESULTS

TAE was successful in 24 patients in the P-group (96%) and 14 in the N-group (40%) (p < 0.001). Univariate analysis revealed "usage of anticoagulant" (p < 0.05) and "larger IVCD (p < 0.05) on preoperative CTA" to be significant predictors of positive extravasation. In the multivariate analysis, IVCD remained significant with an adjusted odds ratio of 1.17. The IVCD cutoff value was 13.6 mm (area under the curve = 0.72, sensitivity = 84.0%, specificity = 54.3%). There were no significant differences in other parameters.

CONCLUSION

Measurement of IVCD in CDB with the cutoff value of 13.6 mm can be a simple and useful indicator to predict the detectability of extravasation following TAE procedures.

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.

The Portal-Venous Enhancement Ratio of the Adrenal Glands and Spleen as a Short-Term Predictor of Mortality in Intensive Care Patients

Background In critically ill ICU patients, initial results showed that opposite enhancement of the adrenal glands (↑) and spleen (↓) on portal venous CT scans was associated with increased mortality over the next days to a month, with short-term mortality being best predicted. The study aimed to validate the adrenal-to-spleen ratio determined in a pilot study concerning mortality prediction.

Method 371 portal venous CT scans of 203 ICU patients (127 men, age: 68.1 ± 14.4 years) were included in the retrospective analysis. Region-of-interest (ROI)-based Hounsfield units of the adrenal glands and the spleen and their density ratio were evaluated. The Matthews correlation coefficient (MCC) and ROC analysis were used to establish a threshold for the adrenal-to-spleen ratio regarding mortality within 72 hours of imaging. The quality of the classification of survivors and deceased patients in the current collective based on the threshold determined in a pilot study and on the current threshold was determined. The precision-recall curve (PRC) was used to test the influence of the addition of patients with low vital risk on the ROC.

Results The current threshold of 1.37 for the adrenal-to-spleen ratio provides good discriminatory power between those who died and those who survived (MCC: 0.87; sensitivity: 83.7 %; specificity: 99.1 %; PPV: 93.2 %; NPV: 97.6 %) and differs only slightly from the threshold of 1.41 determined in the pilot study, which consequently has comparable discriminatory power.

Conclusion As a reproducible image-based prognostic marker, the portal venous adrenal-to-spleen ratio has a high predictive power for short-term death in ICU patients. It is, therefore, suitable as an indicator of high risk of death within 72 hours after imaging.

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The effect of ultrasonographic measurement of vena cava inferior diameter on the prediction of post-spinal hypotension in geriatric patients undergoing spinal anaesthesia

AIMS

In our study, we aimed to investigate whether end-expiratory vena cava inferior (expVCI) diameter and vena cava inferior collapsibility index predicted post-spinal hypotension in geriatric patients undergoing spinal anaesthesia (SA), the correlation between them and other parameters.

MATERIAL AND METHODS

Our prospective study included the American Society of Anesthesiologists (ASA) I-4, 73 patients over 65 years of age, who were scheduled for operation using SA. According to the expVCI diameter displayed with ultrasonographic (USG) before SA, patients with an expVCI diameter less than 1.8 cm previously determined as the threshold value are grouped as 1 (small-VCI) group, those greater than 1.8 cm as 2 (large-VCI) group. Demographic characteristics of the patients, comorbidities, duration and type of operation, basal (preoperative) heart rate, systolic, diastolic, mean blood pressure, peripheral oxygen saturation values before SA and after SA in supine position (0 minute) and 5th, 10th, 15th, 20th, 25th, 30th min and preoperative arterial blood gas parameters, amount of preoperative urine and bleeding, inotropic and fluid requirement, complications were recorded.

RESULTS

Hypotension developed in 28 (38.4%) patients and bradycardia in 14(19.2%) of patients. The patients who developed hypotension had more ASA2 and ASA3 (P = .01), shorter height (P = .02) and smaller expVCI diameter (P = .004). It was observed that they had higher lactate (P = .03), lower pH (P = .006) values and more inotropic agents were administered (P < .001). While the rate of developing hypotension was 51.1% (n = 23) in the patients in the small-VCI group, this rate was 17.9% (n = 5) in the patients in the large-VCI group (P = .004).

CONCLUSION

It was concluded that the expVCI diameter value measured by USG before SA in older adults is effective in predicting post-spinal hypotension with lactate and pH values, which are among the blood gas parameters, and expVCI can be preferred to invasive methods because of its noninvasive, easy and fast application.

Spleno-aortic radiodensity ratio - A distinctive imaging feature to predict short-term outcome in critical care unit

INTRODUCTION

To investigate the value of contrast-enhanced CT findings - splenic and aortic radiodensities and their ratios (spleno-aortic ratio) - in predicting the prognosis of critical care unit patients (CCU).

METHODS

One hundred thirteen continuous CCU patients with an acute deterioration (Group A: 37 women, age: 67.2 ± 14.0 years) were included in the retrospective study. Radiodensities of the spleen and aorta were evaluated by two radiologists separately. The spleno-aortic ratio was calculated. Matthews correlation coefficient (MCC) was used in conjunction with receiver operating characteristic analysis (ROC) to assess if and which parameter was most suitable for short-term mortality prediction. The intra-class correlation coefficient assessed consensus across readers. To validate the results for the best predictor, a second cohort was evaluated (Group B: 354 CT scans).

RESULTS

The portal venous spleno-aortic ratio was best suited to predict 72-hour mortality (AUC = 0.91). A threshold ratio ≤0.53 predicted short-term mortality with a high sensitivity (80.95%) and specificity (96.74%, MCC = 0.79). The post-test probability was 85%, assuming a pre-test probability of 18.6% (72-hour mortality rate). ICCs of HU measurements in the aorta, spleen, and its ratios showed high interrater agreement (ICC: 0.92-0.99). In a control cohort, a threshold ratio ≤0.53 predicted CCU patientś outcome satisfactorily (SENS = 83.93%, SPEC = 97.65%, PPV = 87.00%, NPV = 97.00%).

CONCLUSIONS

The portal venous spleno-aortic ratio serves as a distinctive imaging feature to predict short-term mortality. For CCU patients with a cut-off portal venous spleno-aortic ratio ≤0.53, the risk of dying within three days after CT scan is approximately twenty times higher.

Vascular changes of the superior mesenteric artery (SMA): A new component of the hypovolemic shock complex (HSC)

PURPOSE

To assess the type and frequency of vascular changes in the superior mesenteric artery (SMA) associated with the hypovolemic shock complex (HSC).

METHODS

Twenty-six patients (14 males, 70.6 ± 11.2 years) meeting the criteria for hypovolemic shock complex in computed tomography were examined for the presence of angiographic signs of non-occlusive mesenteric ischemia (NOMI) in the SMA: the string of sausages sign and spasms of the arcades of mesenteric arteries on coronal maximum intensity projection images (MIP). Interrater agreement was assessed using weighted kappa (κ).

RESULTS

Vascular changes of the SMA were visible in almost all of the patients with HSC with a frequency of 88.5 %-96.2 %. Intraclass correlation coefficients indicated a substantial to almost perfect interrater agreement.

CONCLUSIONS

Using computed tomography, it is possible to reliably and reproducibly detect vascular changes in SMA known from angiography in the context of hypoperfusion. The pathological vascular changes also occur more frequently than other classic signs of a CT hypoperfusion complex. Since the qualitative assessment of the SMA requires only a small amount of time, it is suitable as a further criterion for the presence of the CT hypoperfusion complex.