Cyril Charron

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.

Echocardiographic measurement of fluid responsiveness.

Purpose of reviewFluid responsiveness is a relatively new concept. It enables the efficacy of volume expansion to be predicted before use, rather than assessed afterwards, thus avoiding inappropriate fluid infusion. Echocardiography is a fantastic noninvasive tool which can directly visualize the heart and assess cardiac function. Its use was long limited by the absence of accurate indices to diagnose hypovolemia and predict the effect of volume expansion. In the last few years, several French teams have used echocardiography to develop new parameters of fluid responsiveness, taking advantage of its ability to monitor cardiac function beat by beat during the respiratory cycle. Recent findingsIn mechanically ventilated patients perfectly adapted to the respirator, respiratory variations in superior and inferior vena cava diameters and in left ventricular stroke volume have been validated as parameters of fluid responsiveness. In our opinion, the collapsibility index of the superior vena cava is the most reliable of these parameters, but does require transesophageal echocardiography. SummaryEchocardiography has been widely demonstrated to predict fluid responsiveness accurately. This is now a complete and noninvasive tool able to accurately determine hemodynamic status in circulatory failure.

Impact of routine percutaneous coronary intervention after out-of-hospital cardiac arrest due to ventricular fibrillation.

IntroductionSince 2003, we have routinely used percutaneous coronary intervention (PCI) and mild therapeutic hypothermia (MTH) to treat patients < 80 years of age after out-of-hospital cardiac arrest (OHCA) related to ventricular fibrillation. The aim of our study was to evaluate the prognostic impact of routine PCI in association with MTH and the potential influence of age.MethodsWe studied 111 consecutive patients resuscitated successfully following OHCA related to shock-sensitive rhythm. They were divided into five groups according to age: < 45 years (n = 22, group 1), 45 to 54 years (n = 27, group 2), 55 to 64 years (n = 22, group 3), 65 to 74 years (n = 23, group 4) and ≥75 years (n = 17, group 5). Emergency coronary angiography was performed in hemodynamically stable patients < 80 years old, regardless of the electrocardiogram pattern. MTH was targeted to a core temperature of 32°C to 34°C for 24 hours.ResultsMost patients (73%) had coronary heart disease, although its incidence in group 1 was lower than in other groups (41% versus 81%; P = 0.01). In group 1, all patients but one underwent coronary angiography, and 33% of them underwent associated PCI. In group 5, only 53% of patients underwent a coronary angiography and 44% underwent PCI. Overall in-hospital survival was 54%, ranging between 52% and 64% in groups 1 to 4 and 24% in group 5. Time from collapse to return of spontaneous circulation was associated with mortality (odds ratio (OR) = 1.05 (25th to 75th percentile range, 1.03 to 1.08); P < 0.001), whereas PCI was associated with survival (OR = 0.30 (25th to 75th percentile range, 0.11 to 0.79); P = 0.01).ConclusionsWe suggest that routine coronary angiography with potentially associated PCI may favorably alter the prognosis of resuscitated patients with stable hemodynamics who are treated with MTH after OHCA related to ventricular fibrillation. Although age was not an independent cause of death, the clinical relevance of this therapeutic strategy remains to be determined in older people.

Initial resuscitation guided by the Surviving Sepsis Campaign recommendations and early echocardiographic assessment of hemodynamics in intensive care unit septic patients: a pilot study.

Objective: To compare therapeutic interventions during initial resuscitation derived from echocardiographic assessment of hemodynamics and from the Surviving Sepsis Campaign guidelines in intensive care unit septic patients. Design and Setting: Prospective, descriptive study in two intensive care units of teaching hospitals. Methods: The number of ventilated patients with septic shock who were studied was 46. Transesophageal echocardiography was first performed (T1 < 3 hrs after intensive care unit admission) to adapt therapy according to the following predefined hemodynamic profiles: fluid loading (index of collapsibility of the superior vena cava ≥36%), inotropic support (left ventricular fractional area change <45% without relevant index of collapsibility of the superior vena cava), or increased vasopressor support (right ventricular systolic dysfunction, unremarkable transesophageal echocardiography study consistent with sustained vasoplegia). Agreement for treatment decision between transesophageal echocardiography and Surviving Sepsis Campaign guidelines was evaluated. A second transesophageal echocardiography assessment (T2) was performed to validate therapeutic interventions. Results: Although transesophageal echocardiography and Surviving Sepsis Campaign approaches were concordant to manage fluid loading in 32 of 46 patients (70%), echocardiography led to the absence of blood volume expansion in the remaining 14 patients who all had a central venous pressure <12mm Hg. Accordingly, the agreement was weak between transesophageal echocardiography and Surviving Sepsis Campaign for the decision of fluid loading (&kgr;: 0.37 [0.16;0.59]). With a cut-off value <8 mm Hg for central venous pressure, &kgr; was 0.33 [−0.03;0.69]. Inotropes were prescribed based on transesophageal echocardiography assessment in 14 patients but would have been decided in only four patients according to Surviving Sepsis Campaign guidelines. As a result, the agreement between the two approaches for the decision of inotropic support was weak (&kgr;: 0.23 [−0.04;0.50]). No right ventricular dysfunction was observed. No patient had anemia and only three patients with transesophageal echocardiography documented left ventricular systolic dysfunction had a central venous oxygen saturation <70%. Conclusions: A weak agreement was found in the prescription of fluid loading and inotropic support derived from early transesophageal echocardiography assessment of hemodynamics and Surviving Sepsis Campaign guidelines in patients presenting with septic shock.

Noninvasive Assessment of Cardiac Index in Healthy Volunteers: A Comparison Between Thoracic Impedance Cardiography and Doppler Echocardiography

BACKGROUND: Thoracic bioimpedance cardiography (ICG) has been proposed as a noninvasive, continuous, operator-independent, and cost-effective method for cardiac output monitoring. In the present study, we compared cardiac index (CI) measurements with ICG (Niccomo™ device) and transthoracic Doppler echocardiography in resting healthy volunteers undergoing hemodynamic load challenge. METHODS: Twenty-five healthy volunteers (7 men and 18 women, mean age 36 ± 6 yr, body surface area 1.75 ± 0.17 m2) were investigated during three experimental conditions: baseline, positive end-expiratory pressure + 10 cm H2O and lower body positive pressure by means of medical antishock trousers inflated to 30 cm H2O in the abdominal compartment. RESULTS: ICG signal quality was >89% over all sets of measurements. A weak but significant relationship was observed between CITTE and CIICG (r = 0.36; P = 0.002). Agreement between both techniques was 0.94 L · min−1 · m−2 (95% CI: 0.77–1.11), limits of agreement were −0.47 to 2.35 L · min−1 · m−2, and percentage error was 53%. No statistically significant relationships were found between percent changes in CITTE and CIICG after applications of positive end-expiratory pressure + 10 cm H2O (r = 0.21; P = 0.31) and medical antishock trousers (r = 0.22; P = 0.30). CONCLUSIONS: Poor correlation and lack of agreement between absolute values of CI measured by ICG and transthoracic Doppler echocardiography were found in resting healthy volunteers. The Niccomo device was also unreliable for monitoring changes in CI during hemodynamic load challenge.

Evaluation of left ventricular systolic function revisited in septic shock

The meta-analysis of Huang and coworkers failed to find any evidence for a protective effect of a decreased left ventricular (LV) ejection fraction (EF). These results have to be interpreted with caution since in most studies included in the meta-analysis patients with LV systolic dysfunction received inotropic drugs. We have some arguments suggesting that such a treatment may improve macrocirculation and microcirculation and finally prognosis. This paper allows us to clarify the meaning of LV function in septic shock patients. In all experimental models of septic shock using the load-independent parameter of LV systolic function, LV contractility impairment, called septic cardiomyopathy, has been reported to be constant. However, LVEF reflects the coupling between LV contractility and LV afterload. A normal LVEF may be observed when the arterial tone is severely depressed, as in septic shock, despite seriously impaired intrinsic LV contractility. LV systolic function, evaluated using an echocardiograph or another device, is then more a reflection of arterial tone (and its correction) than of intrinsic LV contractility. As a consequence, the incidence of LV systolic dysfunction greatly depends on the time of the evaluation, reflecting the fact that, during resuscitation and treatment, vasoplegia and then LV afterload are corrected, thus unmasking septic cardiomyopathy. With these points in mind, we can revisit the results of Margaret Parkers original study: it is not that the patients with a low EF survived better, but rather that the other patients had an increased mortality due to persistent profound vasoplegia.

PaCO2 and alveolar dead space are more relevant than PaO2/FiO2 ratio in monitoring the respiratory response to prone position in ARDS patients: a physiological study

IntroductionOur aims in this study were to report changes in the ratio of alveolar dead space to tidal volume (VDalv/VT) in the prone position (PP) and to test whether changes in partial pressure of arterial CO2 (PaCO2) may be more relevant than changes in the ratio of partial pressure of arterial O2 to fraction of inspired O2 (PaO2/FiO2) in defining the respiratory response to PP. We also aimed to validate a recently proposed method of estimation of the physiological dead space (VDphysiol/VT) without measurement of expired CO2.MethodsThirteen patients with a PaO2/FiO2 ratio < 100 mmHg were included in the study. Plateau pressure (Pplat), positive end-expiratory pressure (PEEP), blood gas analysis and expiratory CO2 were recorded with patients in the supine position and after 3, 6, 9, 12 and 15 hours in the PP. Responders to PP were defined after 15 hours of PP either by an increase in PaO2/FiO2 ratio > 20 mmHg or by a decrease in PaCO2 > 2 mmHg. Estimated and measured VDphysiol/VT ratios were compared.ResultsPP induced a decrease in Pplat, PaCO2 and VDalv/VT ratio and increases in PaO2/FiO2 ratios and compliance of the respiratory system (Crs). Maximal changes were observed after six to nine hours. Changes in VDalv/VT were correlated with changes in Crs, but not with changes in PaO2/FiO2 ratios. When the response was defined by PaO2/FiO2 ratio, no significant differences in Pplat, PaCO2 or VDalv/VT alterations between responders (n = 7) and nonresponders (n = 6) were observed. When the response was defined by PaCO2, four patients were differently classified, and responders (n = 7) had a greater decrease in VDalv/VT ratio and in Pplat and a greater increase in PaO2/FiO2 ratio and in Crs than nonresponders (n = 6). Estimated VDphysiol/VT ratios significantly underestimated measured VDphysiol/VT ratios (concordance correlation coefficient 0.19 (interquartile ranges 0.091 to 0.28)), whereas changes during PP were more reliable (concordance correlation coefficient 0.51 (0.32 to 0.66)).ConclusionsPP induced a decrease in VDalv/VT ratio and an improvement in respiratory mechanics. The respiratory response to PP appeared more relevant when PaCO2 rather than the PaO2/FiO2 ratio was used. Estimated VDphysiol/VT ratios systematically underestimated measured VDphysiol/VT ratios.

Lung "recruitment" or lung overinflation maneuvers?

onstrated that a lung “recruitment” maneuver produced an acute right ventricular overload [1]. The hallmark of this overload was a leftward septal shift reducing the left ventricular size [2]. From a hemodynamic point of view, whereas a true recruitment should reduce pulmonary vascular resistance, lung overinflation should increase it [3]. Thus, the “recruitment” maneuvers performed by Nielsen et al. likely did not produce any substantial “recruitment” in their patients, but an acute overinflation [1]. Recorded in patients with healthy lungs containing few atelectatic areas, Nielsen’s results are to be expected. In a 54-year-old woman with severe ARDS due to Legionella pneumonia (PaO2/FIO2 38 mmHg, total compliance 12 ml/cm H2O, chest X-ray in Fig. 1), we also performed a “recruitment” maneuver by applying a pressure of 40 cm H2O for 30 s to the airway on the 2nd day of respiratory support. We recorded the short-axis view of the left ventricle by transgastric echocardiography just before and during the “recruitment” maneuver. We immediately observed the septal shift described by Nielsen et al. (see Fig. 2 and the video presented as online additional material). This dangerous maneuver was, of course, not repeated, and the patient finally recovered with our usual strategy, using a low PEEP (5 cm H2O) combined with prone positioning. This observation strongly suggests that, as for a normal lung, “recruitment” maneuvers performed in an ARDS patient essentially produce overinflation. The video online shows a short axis view of the left ventricle (LV) by transgastric echocardiography just before and during the “recruitment” maneuver. Note that the maneuver induced right ventricular overload, as demonstrated by the flattening of the interventricular septum.

Value and determinants of the mean systemic filling pressure in critically ill patients

Mean systemic filling pressure (Pmsf) is a major determinant of venous return. Its value is unknown in critically ill patients (ICU). Our objectives were to report Pmsf in critically ill patients and to look for its clinical determinants, if any. We performed a prospective study in 202 patients who died in the ICU with a central venous and/or arterial catheter. One minute after the heart stopped beating, intravascular pressures were recorded in the supine position after ventilator disconnection. Parameters at admission, during the ICU stay, and at the time of death were prospectively collected. One-minute Pmsf was 12.8 ± 5.6 mmHg. It did not differ according to gender, severity score, diagnosis at admission, fluid balance, need for and duration of mechanical ventilation, or length of stay. Nor was there any difference according to suspected cause of death, classified as shock (cardiogenic, septic, and hemorrhagic) and nonshock, although a large variability of values was observed. The presence of norepinephrine at the time of death (102 patients) was associated with a higher 1-min Pmsf (14 ± 6 vs. 11.4 ± 4.5 mmHg), whereas the decision to forgo life-sustaining therapy (34 patients) was associated with a lower 1-min Pmsf (10.9 ± 3.8 vs. 13.1 ± 5.3 mmHg). In a multiple-regression analysis, norepinephrine (β = 2.67, P = 0.0004) and age (β = -0.061, P = 0.022) were associated with 1-min Pmsf. One-minute Pmsf appeared highly variable without any difference according to the kind of shock and fluid balance, but was higher with norepinephrine.

Acute respiratory distress syndrome: the heart side of the moon.

Purpose of review Circulatory failure is a frequent complication during acute respiratory distress syndrome (ARDS) and is associated with a poor outcome. This review aims at clarifying the mechanisms of circulatory failure during ARDS. Recent findings For the past decades, the right ventricle (RV) has gained a crucial interest since many authors confirmed the high incidence of acute cor pulmonale during ARDS and showed a potential role of the acute cor pulmonale in the poor outcome of ARDS patients. The most important recent progress demonstrated in ARDS ventilatory strategy is represented by the prone position, which has a huge beneficial effect on RV afterload. This review will focus on the mechanisms responsible for the RV dysfunction/failure during ARDS and on the strategy, which allows improving the right ventricular function. Summary The RV has a pivotal role in the circulatory failure of ARDS patients. The ventilatory strategy during ARDS has to pay a peculiar attention to the RV to rigorously control its afterload.