François Jardin

Acute cor pulmonale in acute respiratory distress syndrome submitted to protective ventilation: incidence, clinical implications, and prognosis.

ContextThe incidence of acute cor pulmonale (ACP), a frequent and usually lethal complication of acute respiratory distress syndrome (ARDS) during traditional respiratory support, has never been re-evaluated since protective ventilation gained acceptance. ObjectiveWe performed a longitudinal transesophageal echocardiographic (TEE) study to determine whether this incidence, and its severe implications for prognosis, might have changed in our unit as we altered respiratory strategy. DesignProspective open clinical study. SettingMedical intensive care unit of a university hospital. PatientsSeventy-five consecutive ARDS patients given respiratory support with airway pressure limitation (plateau pressure ≤30 cm H2O). InterventionsACP was defined as a ratio of right ventricular end-diastolic area to left ventricular end-diastolic area in the long axis >0.6 associated with septal dyskinesia in the short axis during TEE examination. ResultsNormal right ventricular function was present in 56 patients, whereas right ventricular dysfunction was observed in 19 patients after 2 days of respiratory support. ACP was associated with pulmonary artery hypertension, increased heart rate, and decreased stroke index. Significant impairment of left ventricular diastolic function was also seen. All echo-Doppler abnormalities were reversible in patients who recovered, and the mortality rate was the same in both groups (32%). However, ACP patients who recovered required a longer period of respiratory support. A multivariate analysis individualized Paco2 level as the sole factor independently associated with ACP, suggesting that ACP development in ARDS is influenced by the severity of lung damage and/or the respiratory strategy. ConclusionEvaluation of right ventricular function by TEE in a group of 75 ARDS patients submitted to protective ventilation revealed the persistence of a 25% incidence of ACP, resulting in detrimental hemodynamic consequences associated with tachycardia. However, ACP was reversible in patients who recovered and did not increase mortality.

Actual incidence of global left ventricular hypokinesia in adult septic shock.

Rationale and Objective:To evaluate the actual incidence of global left ventricular hypokinesia in septic shock. Method:All mechanically ventilated patients treated for an episode of septic shock in our unit were studied by transesophageal echocardiography, at least once a day, during the first 3 days of hemodynamic support. In patients who recovered, echocardiography was repeated after weaning from vasoactive agents. Main measurements were obtained from the software of the apparatus. Global left ventricular hypokinesia was defined as a left ventricular ejection fraction of <45%. Measurements and Main Results:During a 3-yr period (January 2004 through December 2006), 67 patients free from previous cardiac disease, and who survived for >48 hrs, were repeatedly studied. Global left ventricular hypokinesia was observed in 26 of these 67 patients at admission (primary hypokinesia) and in 14 after 24 or 48 hrs of hemodynamic support by norepinephrine (secondary hypokinesia), leading to an overall hypokinesia rate of 60%. Left ventricular hypokinesia was partially corrected by dobutamine, added to a reduced dosage of norepinephrine, or by epinephrine. This reversible acute left ventricular dysfunction was not associated with a worse prognosis. Conclusion:Global left ventricular hypokinesia is very frequent in adult septic shock and could be unmasked, in some patients, by norepinephrine treatment. Left ventricular hypokinesia is usually corrected by addition of an inotropic agent to the hemodynamic support.

Quantitative two-dimensional echocardiography in massive pulmonary embolism: emphasis on ventricular interdependence and leftward septal displacement.

In 14 patients requiring aggressive therapy for circulatory failure resulting from massive pulmonary embolism, hemodynamic and two-dimensional echocardiographic data were obtained at bedside (acute phase) and again after circulatory improvement (intermediate phase) and during recovery. The acute stage was characterized by a low cardiac output state despite inotropic support (cardiac index 1.9 +/- 0.6 liters/min per m2) associated with increased right atrial pressure (12.4 +/- 4.2 mm Hg), increased right ventricular end-systolic and end-diastolic area (12.4 +/- 3.4 and 15.4 +/- 4.1 cm2/m2, respectively) and reduced right ventricular fractional area contraction (20.1 +/- 8.6%). Two-dimensional echocardiography also revealed interventricular septal flattening at both end-systole and end-diastole and markedly decreased left ventricular end-diastolic dimensions. Left ventricular fractional area contraction remained normal. Hemodynamic improvement occurred during the intermediate phase as shown by restoration of cardiac index (3.3 +/- 0.6 liters/min per m2), decrease in right atrial pressure (8.3 +/- 4.8 mm Hg), reduction in right ventricular end-systolic area (9.0 +/- 3.6 cm2/m2 at the intermediate stage and 6.1 +/- 1.8 cm2/m2 at recovery) and end-diastolic area (10.5 +/- 3.6 cm2/m2 at the intermediate stage and 8.9 +/- 2.9 cm2/m2 at recovery) and improvement in right ventricular fractional area contraction (31.5 +/- 16.4%). The interventricular septum progressively returned to a more normal configuration at both end-systole and end-diastole, and left ventricular diastolic dimension steadily increased. It is concluded that circulatory failure secondary to massive pulmonary embolism was mediated through a profound decrease in left ventricular preload, resulting from both pulmonary outflow obstruction and reduced left ventricular diastolic compliance.(ABSTRACT TRUNCATED AT 250 WORDS)

Right ventricular function and positive pressure ventilation in clinical practice: from hemodynamic subsets to respirator settings

When used in patients free of previous cardiorespiratory disease, mechanical ventilation with a normal tidal volume does not have any discernible hemodynamic consequences. Conversely, the presence of a pulmonary disease affecting the bronchial tree, lung parenchyma, or both, may induce extreme conditions for mechanical ventilation. In this setting, an adverse hemodynamic effect may seriously complicate respiratory support.

Influence of superior vena caval zone condition on cyclic changes in right ventricular outflow during respiratory support

Background Adequate fluid resuscitation in critically ill patients undergoing mechanical ventilation remains a difficult challenge, and diastolic and systolic right ventricular (RV) changes produced by positive airway pressure are important to consider in an individual patient with inadequate circulatory adaptation during respiratory support. We hypothesized that insufficient thoracic vena cava filling, predisposing to inspiratory collapse (zone 2 condition), may transiently affect RV outflow. Methods We measured beat-to-beat superior vena caval diameter and Doppler RV outflow during a routine transesophageal echocardiographic examination in 22 patients undergoing mechanical ventilation, all of whom required hemodynamic monitoring, and we calculated a collapsibility index for the superior vena cava as maximal expiratory diameter minus minimal inspiratory diameter, divided by maximal expiratory diameter. Results In 15 patients (group 1), the collapsibility index was low (17 ± 7%) and was associated with a moderate inspiratory decrease in RV outflow (25 ± 17%). However, in seven patients (group 2), we observed a high collapsibility index (71 ± 7%), which was associated with a major inspiratory decrease in RV outflow (69 ± 14%) combined with a reduced pulmonary artery flow period. A rapid volume expansion, only performed on group 2, markedly and significantly reduced both the collapsibility index (15 ± 12%) and the inspiratory decrease in RV outflow (31 ± 20%). Conclusion A major inspiratory decrease in RV outflow associated with a reduced pulmonary artery flow period in a patient undergoing mechanical ventilation reflected a high collapsibility index of the thoracic vena cava, suggesting a zone 2 condition, and may be corrected by blood volume expansion.

Positive end-expiratory pressure titration in acute respiratory distress syndrome patients: impact on right ventricular outflow impedance evaluated by pulmonary artery Doppler flow velocity measurements.

Objective Positive end-expiratory pressure (PEEP) titration in acute respiratory distress syndrome patients remains debatable. We used two mechanical approaches, calculation of the compliance of the respiratory system and determination of the lower inflexion point of the pressure-volume curve of the respiratory system, to identify specific PEEPs (PEEPS and PEEPA) whose impact on right ventricular (RV) outflow was compared with Doppler analysis of pulmonary artery flow velocity. Design Prospective, open, clinical study. Setting Medical intensive care unit of a university hospital. Patients Sixteen consecutive ventilator-dependent acute respiratory distress syndrome patients. Interventions Two PEEPs were determined: PEEPS was the highest PEEP associated with the highest value of respiratory compliance, and PEEPA was the coordinate of the lower inflexion point of the inspiratory pressure-volume curve on the pressure axis plus 2 cm H2O. Measurements and Main Results We observed a large difference between the two PEEPs, with PEEPA (13 + 4 cm H2O) > PEEPS (6 + 3 cm H2O). Changes in RV outflow impedance produced by tidal ventilation with zero end-expiratory pressure (ZEEP) and after application of these two PEEPs were assessed by Doppler study of pulmonary artery flow velocity obtained by a transesophageal approach, with particular reference to the end-expiratory and end-inspiratory pulmonary artery velocity-time integral, as reflecting RV stroke output, and mean acceleration as reflecting RV outflow impedance during an unchanged flow period. A significant inspiratory reduction in pulmonary artery velocity-time integral (from 11.8 + 0.3 to 10.0 + 0.3 cm) and mean acceleration (from 11.9 + 0.9 to 8.0 + 0.9 m/sec2) was observed with ZEEP, showing a reduction in RV stroke index (from 29.0 + 0.9 to 26.0 + 0.6 cm3/m2) by a sudden increase in outflow impedance during tidal ventilation. Application of PEEPA, which improved Pao2 (102 + 40 vs. 65 + 18 torr with ZEEP), worsened the inspiratory drop in RV stroke index (21.6 + 0.8 cm3/m2), resulting in a significant reduction in cardiac index compared with ZEEP (from 3.0 + 1.0 to 2.7 + 1.1). Application of PEEPS, which also significantly improved Pao2 (81 + 21 torr), was associated with a lesser impact on RV outflow impedance (inspiratory mean acceleration: 9.5 + 1 m/sec2) and cardiac index (3.2 + 1.0) than PEEPA. Conclusion RV outflow impedance evaluated by the Doppler technique appeared sensitive to PEEP titration. Application of PEEPA worsened RV systolic function impairment produced by tidal ventilation. Conversely, application of PEEPS reduced RV systolic function impairment, suggesting an association with a lower pulmonary vascular resistance.

Early preload adaptation in septic shock? A transesophageal echocardiographic study.

Background An accepted concept in septic shock is that preload adaptation by acute left ventricular dilatation, when occurring spontaneously or with the aid of volume loading, permits maintenance of an adequate cardiac output, leading to final recovery. From a physiologic point of view, this concept appears debatable because a normal pericardium exerts a restraining action on a normal heart. Methods During a 26-month period, the authors investigated, by transesophageal echocardiography, 40 patients hospitalized in their unit for an episode of septic shock. Transesophageal echocardiography was performed in the first hours after admission, proceeded by correction of any hypovolemia, and stabilization of arterial pressure by vasoactive agent infusion if necessary. Left ventricular dimensions were obtained in long- and short-axis views, permitting calculation of left ventricular ejection fraction (long axis) and fractional area contraction (short axis). Stroke index was simultaneously measured by the Doppler technique. Results Stroke index was strongly correlated with both echocardiographic left ventricle ejection fraction (r = 0.75;P < 0.0001) and left ventricle fractional area contraction (r = 0.76;P < 0.0001), whereas it was independent of echocardiographic left ventricle diastolic dimensions. Conclusions The transesophageal echocardiography study was unable to confirm the reality of the concept of early preload adaptation by left ventricular dilatation in septic shock. Conversely, because left ventricular volume always remained in a normal range after correcting hypovolemia, systolic function was the unique determinant of stroke index in septic shock.

Invasive monitoring combined with two-dimensional echocardiographic study in septic shock

ObjectiveAn investigation into the incidence and the clinical implication of discrepancies which may sometimes occur between invasive and non-invasive hemodynamic evaluation in septic patients.DesignA prospective, consecutive comparison.SettingDepartment of Intensive Care Medicine at a University Hospital.Patients32 patients undergoing therapy for an episode of septic shock.InterventionsConventional hemodynamic support (including volume expansion in all cases and inotropic support if necessary) required to obtain a stable hemodynamic status.Measurement and resultsCardiac output (thermodilution method), cardiac pressures (right heart catheterization) and left ventricular (LV) volumes (two-dimensional echocardiography) were simultaneously recorded. A comparison was thus made between both procedures, particularly concerning preload evaluation and assessment of left ventricular systolic function. Pulmonary artery occlusion pressure measurement was evidenced as an unreliable index of LV end-diastolic volume, determining preload. Assessment of LV systolic function by both methods was conflicting in 11 cases out of the 32.ConclusionsFrequent discrepancies between to invasive and non-invasive procedure were observed. The reasons for these discrepancies, including low vascular resistance, reduced LV compliance, and a possible overestimation of cardiac output by the thermodilution method, are examined in the light of data recorded. It was concluded that invasive hemodynamic evaluation by right heart catheterization in septic patients should be seriously questioned.

Two-dimensional echocardiographic evaluation of right ventricular size and contractility in acute respiratory failure.

Right ventricular size and contractility were evaluated using two-dimensional echocardiography during the first days of respiratory support in 23 patients requiring mechanical ventilation for acute respiratory failure. Nine patients had normal echocardiographic right ventricular function, and nine other patients had a slightly enlarged right ventricle with normal systolic function. The remaining five patients had a severely enlarged right ventricle with abnormal contractile pattern. In these five patients. two-dimensional echocardiography also showed a reduction in left ventricular size suggesting detrimental ventricular interdependence. All 23 patients had normal left ventricular systolic function by two-dimensional echocardiography.

Dobutamine: a hemodynamic evaluation in pulmonary embolism shock.

Intravenous dobutamine was used in ten patients requiring aggressive therapy for massive pulmonary embolism with circulatory failure. Except in one patient who rapidly died, a 30-min dobutamine infusion (8.3 ± 2.7 μg/kg±min) increased both cardiac index (from 1.7 ± 0.4 to 2.3 ± 0.6 L/min ± m2, p < .001) and stroke index (from 16.6 ± 6.7 to 21 ± 5 ml/m2, p < .01), and also reduced pulmonary vascular resistance. Additional hemodynamic improvement was observed until weaning from dobutamine, which was successfully completed 3.3 ± 0.9 days after the start of infusion.