Computed tomographic pulmonary angiography and prognostic significance in patients with acute pulmonary embolism

BACKGROUND

Patients with acute pulmonary embolism (APE) present with a broad spectrum of prognoses. Computed tomographic pulmonary angiography (CTPA) has progressively been established as a first line test in the APE diagnostic algorithm, but estimation of short term prognosis by this method remains to be explored.

METHODS

Eighty two patients admitted with APE were divided into three groups according to their clinical presentation: pulmonary infarction (n = 21), prominent dyspnoea (n = 29), and circulatory failure (n = 32). CTPA studies included assessment of both pulmonary obstruction index and right heart overload. Haemodynamic evaluation was based on systolic aortic blood pressure, heart rate, and systolic pulmonary arterial pressure obtained non-invasively by echocardiography at the time of diagnosis of pulmonary embolism.

RESULTS

The mortality rate was 0%, 13.8% and 25% in the three groups, respectively. Neither the pulmonary obstruction index nor the pulmonary artery pressure could predict patient outcome. In contrast, a significant correlation with mortality was found using the systolic blood pressure (p<0.001) and heart rate (p<0.05), as well as from imaging parameters including right to left ventricle minor axis ratio (p<0.005), proximal superior vena cava diameter (p<0.001), azygos vein diameter (p<0.001), and presence of contrast regurgitation into the inferior vena cava (p = 0.001). Analysis from logistic regression aimed at testing for mortality prediction revealed true reclassification of 89% using radiological variables.

CONCLUSION

These results suggest that CTPA quantification of right ventricular strain is an accurate predictor of in-hospital death related to pulmonary embolism.

BM-573, a dual thromboxane synthase inhibitor and thromboxane receptor antagonist, prevents pig myocardial infarction induced by coronary thrombosis

The aim of this study was to characterize the effects of BM-573 [N-terbutyl-N'-[2-(4'-methylphenylamino)-5-nitro-benzenesulfonyl] urea], a novel dual thromboxane A2 receptor antagonist and thromboxane synthase inhibitor, on myocardial infarction induced by topical ferric chloride (FeCl3) application to the left anterior descending (LAD) coronary artery in anesthetized pigs. All control animals (n = 6) developed an occlusive thrombus in the LAD coronary artery. The mean infarct size, revealed by triphenyl tetrazolium chloride (TTC), and the area at risk, evidenced by Evans blue, corresponded to 35.3 +/- 2.2 and 36.9 +/- 2.1% of the left ventricular mass, respectively. In the BM-573-treated group (n = 6), a drug infusion (10 mg. kg-1. h-1) started 30 min before FeCl3 application and continued throughout the experimentation. Among the BM-573-treated group, four pigs did not develop coronary artery thrombus and their myocardium appeared healthy. Histopathological examination of FeCl3-injured coronary artery revealed an occlusive and adherent thrombus in control group, while pretreatment with BM-573 prevented thrombus formation. In infarcted zones, lack of desmin staining and muscle structure disorganization were obvious. Depletion of myocardial ATP content was observed in the myocardial necrotic region of the control group, but not in myocardial samples of BM-573-treated pigs that did not develop myocardial infarction. When BM-573 prevented LAD artery occlusion, the area under the curve of plasmatic troponin T was reduced by 77% over 6 h. These data suggest that BM-573 could be useful for the prevention of myocardial infarction.

Model-based cardiac diagnosis of pulmonary embolism

A minimal cardiac model has been shown to accurately capture a wide range of cardiovascular system dynamics commonly seen in the intensive care unit (ICU). However, standard parameter identification methods for this model are highly non-linear and non-convex, hindering real-time clinical application. An integral-based identification method that transforms the problem into a linear, convex problem, has been previously developed, but was only applied on continuous simulated data with random noise. This paper extends the method to handle discrete sets of clinical data, unmodelled dynamics, a significantly reduced data set theta requires only the minimum and maximum values of the pressure in the aorta, pulmonary artery and the volumes in the ventricles. The importance of integrals in the formulation for noise reduction is illustrated by demonstrating instability in the identification using simple derivative-based approaches. The cardiovascular system (CVS) model and parameter identification method are then clinically validated on porcine data for pulmonary embolism. Errors for the identified model are within 10% when re-simulated and compared to clinical data. All identified parameter trends match clinically expected changes. This work represents the first clinical validation of these models, methods and approach to cardiovascular diagnosis in critical care.

Model-based identification and diagnosis of a porcine model of induced endotoxic shock with hemofiltration

A previously validated cardiovascular system (CVS) model and parameter identification method for cardiac and circulatory disease states are extended and further validated in a porcine model (N=6) of induced endotoxic shock with hemofiltration. Errors for the identified model are within 10% when the model is re-simulated and compared to the clinical data. All identified parameter trends over time in the experiments match clinically expected changes both individually and over the cohort. This work represents a further clinical validation of these model-based cardiovascular diagnosis and therapy guidance methods for use with monitoring endotoxic disease states.

Unique parameter identification for cardiac diagnosis in critical care using minimal data sets

Lumped parameter approaches for modelling the cardiovascular system typically have many parameters of which a significant percentage are often not identifiable from limited data sets. Hence, significant parts of the model are required to be simulated with little overall effect on the accuracy of data fitting, as well as dramatically increasing the complexity of parameter identification. This separates sub-structures of more complex cardiovascular system models to create uniquely identifiable simplified models that are one to one with the measurements. In addition, a new concept of parameter identification is presented where the changes in the parameters are treated as an actuation force into a feed back control system, and the reference output is taken to be steady state values of measured volume and pressure. The major advantage of the method is that when it converges, it must be at the global minimum so that the solution that best fits the data is always found. By utilizing continuous information from the arterial/pulmonary pressure waveforms and the end-diastolic time, it is shown that potentially, the ventricle volume is not required in the data set, which was a requirement in earlier published work. The simplified models can also act as a bridge to identifying more sophisticated cardiac models, by providing an initial set of patient specific parameters that can reveal trends and interactions in the data over time. The goal is to apply the simplified models to retrospective data on groups of patients to help characterize population trends or un-modelled dynamics within known bounds. These trends can assist in improved prediction of patient responses to cardiac disturbance and therapy intervention with potentially smaller and less invasive data sets. In this way a more complex model that takes into account individual patient variation can be developed, and applied to the improvement of cardiovascular management in critical care.

[Isolated spontaneous dissection of the superior mesenteric artery: a case report]

We report the case of a 38-year-old man admitted at the emergency department for abdominal pain of abrupt onset. Computed tomographic examination revealed a spontaneous isolated dissection of the superior mesenteric artery and an anevrysm of the coeliac artery caused by the arcuate ligament. Outcome was favorable under conservative medical treatment and a three months follow-up was uneventful. This observation offers the opportunity to present recent insights concerning this pathology.

Confirmation of High Cytokine Clearance by Hemofiltration with a Cellulose Triacetate Membrane with Large Pores: An in vivo Study

Objective

To confirm in vivo the hypothesis that hemofiltration with a large pore membrane can achieve significant cytokine clearance.

Method

We used a well-known animal model of endotoxinic shock (0.5 mg/kg of lipopolysaccharide from Escherichia Coli over a period of 30 mins). Six pigs were hemofiltrated for 3 hours with a large pore membrane (78 Å pore, 80 kDa cut off) (Sureflux FH 70, Nipro, Osaka, Japan). The ultrafiltration rate was 45 ml/kg/min. Samples were taken from arterial, venous line and in the ultrafiltrate at T120 and T240. We measured concentrations of interleukin 6, interleukin 10 and albumin.

Results

At T120 and T240, the IL-6 clearances were 22 ± 7 and 15 ± 3 ml/min, respectively. The IL-6 sieving coefficients were 0.97 and 0.7 at T120 and T240, respectively. At T120 and T240, the IL-10 clearances were 14 ± 4 and 10 ± 7 ml/min, respectively. The sieving coefficients were 0.63 and 0.45 at T120 and T240, respectively. The concentrations of IL-6 and IL-10 were the same at T0 and T240. At T60 and T240, the plasmatic albumin concentrations were 24 ± 4 g/L and 23 ± 4 g/L, respectively (p = 0.13).

Conclusions

In this animal model of endotoxinic shock, we confirm the high cytokine clearance observed when hemofiltration is applied to a large pore membrane. The loss of albumin seems negligible. The impact of such clearances on hemodynamic stability and survival remains to be proved.

Effects of U-46619 on pulmonary hemodynamics before and after administration of BM-573, a novel thromboxane A2 inhibitor

We studied the effects on pulmonary hemodynamics of U-46619, a thromboxane A2 (TXA2) agonist, before and after administration of a novel TXA2 receptor antagonist and synthase inhibitor (BM-573). Six anesthetized pigs (Ago group) received 6 consecutive injections of U-46619 at 30-min interval and were compared with six anesthetized pigs (Anta group) which received an increasing dosage regimen of BM-573 10 min before each U-46619 injection. Consecutive changes in pulmonary hemodynamics, including characteristic resistance, vascular compliance, and peripheral vascular resistance, were continuously assessed during the experimental protocol using a four-element Windkessel model. At 2 mg/kg, BM-573 completely blocked pulmonary hypertensive effects of U-46619 but pulmonary vascular compliance still decreased. This residual effect can probably be explained by a persistent increase in the tonus of the pulmonary vascular wall smooth muscles sufficient to decrease vascular compliance but not vessel lumen diameter. Such molecule could be a promising therapeutic approach in TXA2 mediated pulmonary hypertension as it is the case in pulmonary embolism, hyperacute lung rejection and endotoxinic shock.

[Coronary dissection and non-penetrating chest trauma]

The occurrence of an acute myocardial infarction after non-penetrating chest trauma is an extremely rare complication. We report a case of dissection of the left anterior descending artery in a 43 year old man after being punched in the chest. Using data from a literature search relish revealed 76 cases; we review the characteristics of the pathology and its incidence. We also characterize its etiology, anatomy and path physiology. We then consider the diagnostic and therapeutic implications.

Patient specific identification of the cardiac driver function in a cardiovascular system model

The cardiac muscle activation or driver function, is a major determinant of cardiovascular dynamics, and is often approximated by the ratio of the left ventricle pressure to the left ventricle volume. In an intensive care unit, the left ventricle pressure is usually never measured, and the left ventricle volume is only measured occasionally by echocardiography, so is not available real-time. This paper develops a method for identifying the driver function based on correlates with geometrical features in the aortic pressure waveform. The method is included in an overall cardiovascular modelling approach, and is clinically validated on a porcine model of pulmonary embolism. For validation a comparison is done between the optimized parameters for a baseline model, which uses the direct measurements of the left ventricle pressure and volume, and the optimized parameters from the approximated driver function. The parameters do not significantly change between the two approaches thus showing that the patient specific approach to identifying the driver function is valid, and has potential clinically.

Effect of Hemodiafiltration on Pulmonary Hemodynamics in Endotoxic Shock

Hemofiltration can improve pulmonary hemodynamics during septic shock. The main objective of the study was to determine whether hemodiafiltration (HDF) would also have beneficial effects on pulmonary hemodynamics during septic shock. In the Endo group, six anesthetized pigs received a 0.5 mg/kg endotoxin infusion over 30 min. In the HDF group (n = 6), HDF was started 30 min after the end of the endotoxin infusion, while in the Control group (n = 4) they received HDF but no endotoxin infusion. Pulmonary hemodynamics were analyzed in detail with a four-element windkessel model. Although in the Control group, HDF did not alter pulmonary hemodynamic parameters, in the HDF group, it was responsible for an amplification of the deleterious pulmonary vascular response to endotoxin insult. Our results show that HDF must be used cautiously in septic shock since it can precipitate right heart failure by increasing pulmonary vascular resistance.

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine: Brussels, Belgium. 15-18 March 2016

[This corrects the article DOI: 10.1186/s13054-016-1208-6.].

Effects of BM-573, a novel thromboxane A2 inhibitor, on pulmonary hemodynamics in endotoxic shock

Thromboxane A2 is considered to be partially responsible for the increase in pulmonary vascular resistance observed after endotoxin administration and to participate in proinflammatory reactions. The effects of a novel dual TXA2 synthase inhibitor and TXA2 receptor antagonist (BM-573) on pulmonary hemodynamics were investigated in endotoxic shock. 30 mins before the start of a 0.5 mg/kg endotoxin infusion, 6 pigs (Endo group) received a placebo infusion and 6 other pigs (Anta group) received a BM-573 infusion. In Endo group, pulmonary artery pressure increased from 25 +/- 1.8 (T0) to 42 +/- 2.3 mmHg (T60) (p < 0.05) after endotoxin infusion while, in Anta group, it increased from 23 +/- 1.6 (T0) to 25 +/- 1.5 mmHg (T60). This difference is due to a reduction in pulmonary vascular resistance in Anta group while pulmonary arterial compliance changes in Endo group remained comparable with the evolution in Anta group. In Endo group, PaO2 decreased from 131 +/- 21 (T0) to 74 +/- 12 mmHg (T300) (p < 0.05), while in Anta group, PaO2 was 241 +/- 31 mmHg at the end of the experimental period (T300). These results demonstrate that TXA2 plays a major role in pulmonary vascular changes during endotoxin insult. Concomitant inhibition of TXA2 synthesis and of TXA2 receptors by BM-573 inhibited the pulmonary vasopressive response during the early phase of endotoxin shock as well as the deterioration in arterial oxygenation.

[Application of the Simplified Acute Physiology Score II (SAPS II) in a medical intensive care unit]

OBJECTIVE

Our study was to assess the validity of SAPS II (New Simplified Acute Physiology Score) to predict the probability of in hospital mortality, in a cohort of patient admitted to a medical intensive care unit.

STUDY DESIGN

Prospective study.

PATIENTS AND METHODS

Out of 467 the 525 patients admitted were included. SAPS score and in hospital mortality prediction were calculated for each of them.

RESULTS

In this group, SAPS II offered a satisfactory discrimination power with an area under the curve of 0.843. However, calibration showed a lack of fit (chi 2 = 28.5, P < 0.001), with an overall under prediction of mortality (observed versus expected ratio of 1.12).

CONCLUSION

This SAPS II lower predicting accuracy in a specific population and for individual outcome prediction may reduce its interest in clinical decision-making.

Direct and indirect injuries of the pharynx and larynx

Direct and indirect injuries of the pharynx and larynx. The neck is characterized by a relatively complex anatomy and a very compact content. It therefore forms an extremely vulnerable part of the human body. Although uncommon, aero-digestive tract injuries caused by trauma present a challenging situation for both the emergency doctor and the head and neck surgeon. Clinical presentations may vary from severe acute distress with immediate life-threatening airway obstruction to apparently more reassuring situations. However, the latter turn out to be frequently misleading, since patients may deteriorate suddenly as the result of unrecognized injuries. In such cases, delayed diagnosis is often associated with increased morbidity and mortality. Due to its role in phonation, breathing and alimentation, injuries to the aero-digestive tract also expose the patient to severe later impairment and a poorer quality of life. Comprehensive airway control remains the highest and often most challenging priority for the emergency physician. Careful clinical examination combined with endoscopy and computed tomography imaging form the key elements in diagnosis and early recognition of patients who may require surgical management.

[Advanced nurse triage for emergency department]

To cope with overcrowding, a consequence of their constant growth, emergency departments have implemented operational strategies based on triage systems. Despite its interest, nurse triage has been limited by several hindrances, and new strategies are emerging. Among those, advanced nurse triage, allowing a nurse to initiate the diagnostic process just after categorization of the patient, seems to be promising. A study on advanced nurse triage for patients presenting with chest pain has been conducted in the emergency department of the CHU of Liège. The encouraging results obtained following this new system demonstrate a reduction of the delay to management of patients, and a reduction of the total length of stay in the emergency unit mainly during overcrowding periods. Advanced nurse triage, in addition to a conventional triage during overcrowding periods, improves management of patients in terms of time and reduces the total time spent in the emergency department.

[How I treat ... out-of-hospital cardiac arrest. The role of the emergency medical dispatcher]

Sudden cardiac arrest is an event associated with a very low survival rate. The latter is inversely proportional to the duration of the cardiovascular arrest. The chain of survival concept is a sequence of 4 events to be carried out as fast as possible with a view to ensure the patient's survival. This sequence consists of early access to and activation of the emergency medical system, early initiation of basic cardiopulmonary resuscitation, early defibrillation and early specialized care. The number of potential witnesses trained in Basic Life Support (BLS) does not guarantee an adequate basic resuscitation before the arrival of medical aid. In order to optimize the management of victims and callers, the concept of dispatching-assisted cardiopulmonary resuscitation based on a structured protocol has been implemented. The implementation of this plan to improve the quality of call handling required training and assessment of impacts on beneficiaries. The research datashow a reduction of the duration of cardiac arrest, an increase in resuscitation initiated by a witness, an improved survival rate, and a decreased stress and unanimous approval of dispatchers. Currently, the process is being improved and sustained.

[Psychological impact of out-of-hospital cardiopulmonary resuscitation (CPR) on the witness engaged in gestures of survival]

The occurrence of an unexpected sudden death puts the witnesses of this event in a situation of high emotional impact. The benefit to allow the families of victims to dispense the first resuscitation techniques has been emphasized. However, little data exist on the emotional impact of a cardio-respiratory arrest outside the hospital on the witness, who is often a close family member. Recently, we investigated the presence of psychological distress and the factors influencing it, in the active practice of basic resuscitation gestures by the witnesses guided by the operator 112. Resuscitation by a person not belonging to the medical corps seems not to be devoid of psychological impact. Indeed, the presence of psychological distress is observed for most of witnesses questioned 6 to 10 days after the call but also 3 months later. This work highlights therefore the importance of identifying the coping strategies involved, in order to promote potentially beneficial strategies and limit the trauma associated with this type of event.

[A wing clipping beverage]

Chronic consumption of soda energizing caffeine has known a growing success. Its deleterious effects, however, are often ignored. We report a case of tetraparesis associated with chronic excessive consumption of cola. The development of muscle weakness is variable, resulting from a hyperpolarization of excitable membranes. The outcome is most often favorable after potassium supplementation and interruption of the offending beverage consumption. The mechanisms involved are multiple and involve both a leakage of fecal and urinary potassium and a potassium entry into the intracellular compartment. Other mechanisms related to caffeine are also involved. It therefore appears mandatory to assess the consumption of such beverages in the presence of hypokalemia and muscle weakness.