Aortic Flow Variation Research Articles

Predicting and Measuring Fluid Responsiveness by Hemodynamic Indices versus Transthoracic Echocardiography in Clinically Shocked Patients

Abstract Background In the last decades dynamic measures had evolved as a better solution to predict fluid responsiveness in clinically shocked patients, out of multiple dynamic parameters we chose transthoracic echocardiographic based measurements of variations of aortic blood flow and inferior vena caval diameter. Aim of the Work to assess accuracy of transthoracic echo measured variation in aortic blood flow and inferior vena caval diameter with limited bolus crystalloid infusion in predicting fluid responsiveness in patients with clinical shock. Patients and Methods This study included 51 selected Patients with acute circulatory failure secondary to clinical shock admitted to ICU. All patients had undergone basic transthoracic echocardiographic (TTE) assessment of aortic blood flow (using left ventricular outflow tract velocity time integral as a surrogate) and inferior vena caval diameter changes with respiratory cycle, these measures were obtained at time of diagnosis of shock and repeated after infusion of 300 ml crystalloid fluid bolus (over fifteen minutes). Results Our results had revealed significant difference between responders and non-responders regarding aortic flow variation after fifteen minutes. Conclusion Based on the results obtained in this study, it was proved that transthoracic echocardiography can be used as an accurate method to predict fluid responsiveness in shocked patient with fluid challenge.

Role of Point-of-Care Ultrasonography for the Management of Sepsis and Septic Shock.

Sepsis and septic shock remain a major cause of morbidity and mortality globally. In recent years, the outcome of patients with sepsis and septic shock has gradually improved, in part due to early recognition and timely appropriate management. Bedside physical examination can be of limited value to identify the source of infection and to decide appropriate management. Moreover, the clinical status of these patients can change rapidly, as a part of disease progression or in response to treatment or intervention. Research articles, review papers and online contents related to point-of-care ultrasound for the management of patients with sepsis and septic shock were reviewed. Point-of-care ultrasonography can be a valuable bedside tool to rapidly identify the potential source of infection and associated organ dysfunction. It can also help to guide management to predict fluid responsiveness by assessing the variation of inferior venacava with respiration, ventricular size and aortic flow variation. Response to various interventions like a fluid challenge or administration of inotropes can be assessed at the bedside. Point-of-care ultrasound can also enhance safety and increase the success of bedside procedures like central venous cannulation and drainage of pleural effusion. Bedside ultrasound can help to individualize management of patients with sepsis and septic shock and may potentially improve patient outcome.

Assessment of loading conditions with cardiac ultrasound. A comprehensive review.

Optimization of the preloading conditions and concomitant determination of endpoints of fluid administration are the most frequent therapeutic actions in critically ill patients. Besides a clinical appraisal, reproducible data should be acquired at the bedside to estimate the adequacy of fluid resuscitation. The dynamic assessment and determination of fluid responsiveness plays a major role in this respect. Right-sided cardiac variables, such as inferior and superior caval vein diameter variation during mechanical ventilation, are easily obtained with cardiac ultrasound. Moreover, left sided variables, including aortic flow variation, with intermittent swings of intrathoracic pressure during mechanical ventilation, may be achieved non-invasively with Doppler-echocardiography. Both in terms of resuscitation, as well as correct interpretation of various two-dimensional and Doppler variables, it is essential to acquire a clear understanding of the filling status of a patient. Doppler-echocardiography plays herein a pivotal role.

Influence of Respiratory Rate on Stroke Volume Variation in Mechanically Ventilated Patients

Heart-lung interactions are used to evaluate fluid responsiveness in mechanically ventilated patients, but these indices may be influenced by ventilatory conditions. The authors evaluated the impact of respiratory rate (RR) on indices of fluid responsiveness in mechanically ventilated patients, hypothesizing that pulse pressure variation and respiratory variation in aortic flow would decrease at high RRs. In 17 hypovolemic patients, thermodilution cardiac output and indices of fluid responsiveness were measured at a low RR (14-16 breaths/min) and at the highest RR (30 or 40 breaths/min) achievable without altering tidal volume or inspiratory/expiratory ratio. An increase in RR was accompanied by a decrease in pulse pressure variation from 21% (18-31%) to 4% (0-6%) (P < 0.01) and in respiratory variation in aortic flow from 23% (18-28%) to 6% (5-8%) (P < 0.01), whereas respiratory variations in superior vena cava diameter (caval index) were unaltered, i.e., from 38% (27-43%) to 32% (22-39%), P = not significant. Cardiac index was not affected by the changes in RR but did increase after fluids. Pulse pressure variation became negligible when the ratio between heart rate and RR decreased below 3.6. Respiratory variations in stroke volume and its derivates are affected by RR, but caval index was unaffected. This suggests that right and left indices of ventricular preload variation are dissociated. At high RRs, the ability to predict the response to fluids of stroke volume variations and its derivate may be limited, whereas caval index can still be used.

Transient Constrictive Pericarditis With Videographic Display of Kussmaul Sign

A 24-year-old white man with no significant past medical history presented with sharp chest pain that increased with inspiration and radiated to his left shoulder and neck. The pain had begun 1 week before presentation. The patient denied accompanying shortness of breath, dizziness, palpitations, edema, or syncope. The patient recalled having had an upper respiratory infection that he presumed was viral ≈2 weeks before this admission. A review of systems was noncontributory. He denied any unusual exposures. He used alcohol occasionally and denied recreational drug use. On examination, he was afebrile with a blood pressure of 110/56 mm Hg, pulse rate of 90 bpm, and normal oxygen saturations. Pulsus paradoxus of 13 mm Hg was measured, and no jugular venous distension was noted. He appeared to be in moderate distress from the pain. Cardiac examination revealed faint heart sounds without a pericardial rub or murmurs. Complete blood count and serum chemistries were within normal …

Esophageal Doppler monitoring predicts fluid responsiveness in critically ill ventilated patients

To test whether fluid responsiveness can be predicted by the respiratory variation in aortic blood flow and/or the flow time corrected for heart rate monitored with esophageal Doppler. Prospective study in a 24-bed medical intensive care unit of a university hospital. 38 mechanically ventilated patients with sinus rhythm and without spontaneous breathing activity in whom volume expansion was planned. The aortic blood flow was measured using an esophageal Doppler monitoring device before and after fluid infusion (500 ml NaCl 0.9% over 10 min). The variation in aortic blood flow over a respiratory cycle between its minimal and maximal values was calculated. The flow time was also measured. Aortic blood flow increased by at least 15% after volume expansion in 20 patients (defined as responders). Before fluid infusion the respiratory variation in aortic flow was higher in responders than in nonresponders (28+/-12% vs. 12+/-5%). It significantly decreased after volume expansion (18+/-11%) in responders only. A respiratory variation in aortic flow before volume expansion of at least 18% predicted fluid responsiveness with a sensitivity of 90% and a specificity of 94%. Flow time increased with fluid infusion in responders and nonresponders. A flow time corrected for heart rate below 277 ms predicted fluid responsiveness with a sensitivity of 55% and a specificity of 94%. The area under the ROC curve generated for variation in aortic blood flow ABF was greater than that generated for flow time. The respiratory variation in aortic blood flow reliably predicts fluid responsiveness in patients with sinus rhythm and without breathing activity.

Functional hemodynamic monitoring.

Hemodynamic monitoring is a central component of intensive care. Patterns of hemodynamic variables often suggest cardiogenic, hypovolemic, obstructive, or distributive (septic) etiologies to cardiovascular insufficiency, thus defining the specific treatments required. Monitoring increases in invasiveness, as required, as the risk for cardiovascular instability-induced morbidity increases because of the need to define more accurately the diagnosis and monitor the response to therapy. Monitoring is also context specific: requirements during cardiac surgery will be different from those in the intensive care unit or emergency department. Solitary hemodynamic values are useful as threshold monitors (e.g. hypotension is always pathological, central venous pressure is only elevated in disease). Some hemodynamic values can only be interpreted relative to metabolic demand, whereas others have multiple meanings. Functional hemodynamic monitoring implies a therapeutic application, independent of diagnosis such as a therapeutic trial of fluid challenge to assess preload responsiveness. Newer methods for assessing preload responsiveness include monitoring changes in central venous pressure during spontaneous inspiration, and variations in arterial pulse pressure, systolic pressure, and aortic flow variation in response to vena caval collapse during positive pressure ventilation or passive leg raising. Defining preload responsiveness using these functional measures, coupled to treatment protocols, can improve outcome from critical illness. Potentially, as these and newer, less invasive hemodynamic measures are validated, they could be incorporated into such protocolized care in a cost-effective manner.