Comparison of Echocardiographic Indices Used to Predict Fluid Responsiveness in Ventilated Patients.

RATIONALE: Assessment of fluid responsiveness relies on dynamic echocardiographic parameters that have not yet been compared in large cohorts. OBJECTIVES: To determine the diagnostic accuracy of dynamic parameters used to predict fluid responsiveness in ventilated patients with a circulatory failure of any cause. METHODS: In this multicenter prospective study, respiratory variations of superior vena cava diameter (∆SVC) measured using transesophageal echocardiography, of inferior vena cava diameter (∆IVC) measured using transthoracic echocardiography, of the maximal Doppler velocity in left ventricular outflow tract (∆VmaxAo) measured using either approach, and pulse pressure variations (∆PP) were recorded with the patient in the semirecumbent position. In each patient, a passive leg raise was performed and an increase of aortic velocity time integral greater than or equal to 10% defined fluid responsiveness. MEASUREMENTS AND MAIN RESULTS: Among 540 patients (379 men; age, 65 ± 13 yr; Simplified Acute Physiological Score II, 59 ± 18; Sequential Organ Failure Assessment, 10 ± 3), 229 exhibited fluid responsiveness (42%). ∆PP, ∆VmaxAo, ∆SVC, and ∆IVC could be measured in 78.5%, 78.0%, 99.6%, and 78.1% of cases, respectively. ∆SVC greater than or equal to 21%, ∆VmaxAo greater than or equal to 10%, and ∆IVC greater than or equal to 8% had a sensitivity of 61% (95% confidence interval, 57-66%), 79% (75-83%), and 55% (50-59%), respectively, and a specificity of 84% (81-87%), 64% (59-69%), and 70% (66-75%), respectively. The area under the receiver operating characteristic curve of ∆SVC was significantly greater than that of ∆IVC (P = 0.02) and ∆PP (P = 0.01). CONCLUSIONS: ∆VmaxAo had the best sensitivity and ∆SVC the best specificity in predicting fluid responsiveness. ∆SVC had a greater diagnostic accuracy than ∆IVC and ∆PP, but its measurement requires transesophageal echocardiography.

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<12 mm Hg. Accordingly, the agreement was weak between transesophageal echocardiography and Surviving Sepsis Campaign for the decision of fluid loading (κ: 0.37 [0.16;0.59]). With a cut-off value<8 mm Hg for central venous pressure, κ 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 (κ: 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.

Organ failure in the ICU: cardiac alterations.

Cardiac alterations may be defined as changes that lead to abnormal cardiac function. They include decrease in preload, increase in afterload, and depressed cardiac contractility. Cardiac dysfunction differs from cardiac failure: cardiac performance is altered, but this does not necessarily mean that the cardiovascular system is failing. Several tools are available to detect cardiac alterations. Some may continuously assess cardiac performance by mainly or exclusively measuring cardiac output, but no information is given about the mechanisms underlying the cardiac output decrease. Doppler echocardiography allows noncontinuous cardiac monitoring, but it is perfectly adapted to evaluation of cardiac performance. It directly visualizes cardiac contractility and assesses cardiac preload. Only when there is an imbalance between oxygen demand and oxygen transport is correction of cardiac alterations required. But the truth is that no study supports the use of one treatment rather than another. Changes in respiratory settings or in respiratory mechanics induce changes in cardiac function and must then be considered in the strategy.

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.

INTRODUCTION: Our 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. METHODS: Thirteen 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. RESULTS: PP 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)). CONCLUSIONS: PP 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.

Cardiac tamponade.

PURPOSE OF REVIEW: To re-emphasize the epidemiology, pathophysiology, diagnosis, and treatment of cardiac tamponade. RECENT FINDINGS: Cardiac tamponade is a cause of obstructive shock. Incidence of cardiac tamponade is poorly documented. In cardiac tamponade, the pericardial pressure may reach 15-20  mmHg, leading to an equalization of pressures into the cardiac chambers and to a huge decrease in the systemic venous return. The right atrial transmural pressure becomes negligible. A competition between the right atrium and the right ventricle and between both ventricles is occurring. Deep inspiration allows the patients to maintain the systemic venous return at a certain level. Echocardiography is the key tool to diagnose a pericardial effusion, to detect its bad-tolerance, and to guide the treatment. In some situations following cardiac surgery, transesophageal echocardiography is mandatory. Treatment aims to restore a 'normal' blood pressure by fluid loading (with caution) and catecholamines and to drain the pericardium in emergency. SUMMARY: Cardiac tamponade is responsible for an obstructive shock. Causes of pericardial effusion are numerous. Echocardiography is the fundamental tool for the diagnosis and therapeutic management. Volume resuscitation and catecholamines are temporary treatments, pericardial drainage remaining the only effective treatment.

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

INTRODUCTION: Since 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. METHODS: We 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. RESULTS: Most 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). CONCLUSIONS: We 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.

Routine prone positioning in patients with severe ARDS: feasibility and impact on prognosis.

PURPOSE: Since 1997, we have routinely used prone positioning (PP) in patients who have a PaO(2)/FiO(2) below 100 mmHg after 24-48 h of mechanical ventilation and who are ventilated using a low stretch ventilation strategy. We report here the characteristics and prognosis of this subgroup of patients with severe lung injury to illustrate the feasibility, role, and impact of routine PP in acute respiratory distress syndrome (ARDS). RESULTS: A total of 218 patients were admitted because of ARDS between 1997 and 2009. Of these patients, 57 (26%) were positioned prone because of a PaO(2)/FiO(2) below 100 mmHg after 24-48 h of mechanical ventilation. Age was 51 ± 16 years, PaO(2)/FiO(2) 74 ± 19, and PaCO(2) 54 ± 10 mmHg. The lung injury score was 3.13 ± 0.15. Tidal volume was 7 ± 2 mL/kg, PEEP 5.6 ± 1.2 cmH(2)O, and plateau pressure 27 ± 3 cmH(2)O. Prone sessions lasted 18 h/day and 3.4 ± 1.1 sessions were required to obtain an FiO(2) below 60%. The 60-day mortality was 19% and death occurred after 12 ± 5 days. The ratio between observed and predicted mortality was 0.43. In patients with a PaO(2)/FiO(2) below 60 mmHg, the 60-day mortality was 28%. Logistic regression analysis showed that among the 218 patients, PP appeared to be protective with an odds ratio of 0.35 [0.16-0.79]. CONCLUSION: We demonstrate the clinical feasibility of routine PP in patients with a PaO(2)/FiO(2) below 100 mmHg after 24-48 h and suggest that, when combined with a low stretch ventilation strategy, it is protective with a high survival rate.

Acute respiratory distress syndrome, mechanical ventilation, and right ventricular function.

PURPOSE OF REVIEW: To reiterate the effects of positive pressure ventilation on right ventricular (RV) function in acute respiratory distress syndrome (ARDS), to explain in which conditions acute cor pulmonale (ACP) may worsen prognosis, and to define an approach to protection of the right ventricle. RECENT FINDINGS: In unselected populations of ARDS patients, large studies have reported a 25% incidence of ACP. ACP has deleterious consequences, such as patent foramen ovale shunting and fewer ventilator-free days within the first 28 days. ACP may also worsen prognosis if not taken into account to adapt respiratory settings to RV function. ACP reflects the balance between lung recruitment and lung overdistension. To prevent ACP or to correct it, plateau pressure must be below 27-28 cmH2O, hypercapnia controlled, intrinsic positive end-expiratory pressure (PEEP) avoided, and a 'low' PEEP applied. Recent findings have suggested a negative correlation between the deleterious effect of PEEP on RV function and its ability to recruit the lung. SUMMARY: Routine RV function assessment leads to an approach to mechanical ventilation in ARDS patients designed for protection of the right ventricle. This approach called 'RV protective approach' must be associated with prone positioning, a method of ventilation that improves RV function.