Assessment of fluid unresponsiveness guided by lung ultrasound in abdominal surgery: a prospective cohort study.

A fluid challenge can generate an infraclinical interstitial syndrome that may be detected by the appearance of B-lines by lung ultrasound. Our objective was to evaluate the appearance of B-lines as a diagnostic marker of preload unresponsiveness and postoperative complications in the operating theater. We conducted a prospective, bicentric, observational study. Adult patients undergoing abdominal surgery were included. Stroke volume (SV) was determined before and after a fluid challenge with 250 mL crystalloids (Delta-SV) using esophageal Doppler monitoring. Responders were defined by an increase of Delta-SV > 10% after fluid challenge. B-lines were collected at four bilateral predefined zones (right and left anterior and lateral). Delta-B-line was defined as the number of newly appearing B-lines after a fluid challenge. Postoperative pulmonary complications were prospectively recorded according to European guidelines. In total, 197 patients were analyzed. After a first fluid challenge, 67% of patients were responders and 33% were non-responders. Delta-B-line was significantly higher in non-responders than responders [4 (2-7) vs 1 (0-3), p < 0.0001]. Delta-B-line was able to diagnose fluid non-responders with an area under the curve of 0.74 (95% CI 0.67-0.80, p < 0.0001). The best threshold was two B-lines with a sensitivity of 80% and a specificity of 57%. The final Delta-B-line could predict postoperative pulmonary complications with an area under the curve of 0.74 (95% CI 0.67-0.80, p = 0.0004). Delta-B-line of two or more detected in four lung ultrasound zones can be considered to be a marker of preload unresponsiveness after a fluid challenge in abdominal surgery.The objectives and procedures of the study were registered at Clinicaltrials.gov (NCT03502460; Principal investigator: Stéphane BAR, date of registration: April 18, 2018).

Arterial Load and Norepinephrine Are Associated With the Response of the Cardiovascular System to Fluid Expansion.

BACKGROUND: Fluid responsiveness has been extensively studied by using the preload prism. The arterial load might be a factor modulating the fluid responsiveness. The norepinephrine (NE) administration increases the arterial load and modifies the vascular properties. The objective of the present study was to determine the relationship between fluid responsiveness, preload, arterial load, and NE use. We hypothesized that as a preload/arterial load, NE use may affect fluid responsiveness. METHODS: The retrospective multicentered analysis of the pooled data from 446 patients monitored using the transpulmonary thermodilution before and after fluid expansion (FE) was performed. FE was standardized between intensive care units (ICUs). The comparison of patients with and without NE at the time of fluid infusion was performed. Stroke volume (SV) responsiveness was defined as an increase of more than 15% of SV following the FE. Pressure responsiveness was defined as an increase of more than 15% of mean arterial pressure (MAP) following the FE. Arterial elastance was used as a surrogate for the arterial load. RESULTS: A total of 244 patients were treated with NE and 202 were not treated with NE. By using the univariate analysis, arterial elastance was correlated to SV variations with FE. However, the SV variations were not associated with NE administration (26 [15; 46]% vs. 23 [10; 37]%, p = 0.12). By using the multivariate analysis, high arterial load and NE administration were associated with fluid responsiveness. The association between arterial elastance and fluid responsiveness was less important in patients treated with NE. Arterial compliance increased in the absence of NE, but it did not change in patients treated with NE (6 [-8; 19]% vs. 0 [-13; 15]%, p = 0.03). The changes in total peripheral and arterial elastance were less important in patients treated with NE (-8 [-17; 1]% vs. -11 [-20; 0]%, p < 0.05 and -10 [-19; 0]% vs. -16 [-24; 0]%, p = 0.01). CONCLUSION: The arterial load and NE administration were associated with fluid responsiveness. A high arterial load was associated with fluid responsiveness. In patients treated with NE, this association was lower, and the changes of arterial load following FE seemed to be driven mainly by its resistive component.

Doppler Echocardiographic Indices Are Specific But Not Sensitive to Predict Pulmonary Artery Occlusion Pressure in Critically Ill Patients Under Mechanical Ventilation.

OBJECTIVES: The objective of this study was to prospectively evaluate the ability of transthoracic echocardiography to assess pulmonary artery occlusion pressure in mechanically ventilated critically ill patients. DESIGN: In a prospective observational study. SETTING: Amiens University Hospital Medical ICU. PATIENTS: Fifty-three mechanically ventilated patients in sinus rhythm admitted to our ICU. INTERVENTION: Transthoracic echocardiography was performed simultaneously to pulmonary artery catheter. MEASUREMENTS AND MAIN RESULTS: Transmitral early velocity wave recorded using pulsed wave Doppler (E), late transmitral velocity wave recorded using pulsed wave Doppler (A), and deceleration time of E wave were recorded using pulsed Doppler as well as early mitral annulus velocity wave recorded using tissue Doppler imaging (E'). Pulmonary artery occlusion pressure was measured simultaneously using pulmonary artery catheter. There was a significant correlation between pulmonary artery occlusion pressure and lateral ratio between E wave and E' (E/E' ratio) (r = 0.35; p < 0.01), ratio between E wave and A wave (E/A ratio) (r = 0.41; p < 0.002), and deceleration time of E wave (r = -0.34; p < 0.02). E/E' greater than 15 was predictive of pulmonary artery occlusion pressure greater than or equal to 18 mm Hg with a sensitivity of 25% and a specificity of 95%, whereas E/E' less than 7 was predictive of pulmonary artery occlusion pressure less than 18 mm Hg with a sensitivity of 32% and a specificity of 81%. E/A greater than 1.8 yielded a sensitivity of 44% and a specificity of 95% to predict pulmonary artery occlusion pressure greater than or equal to 18 mm Hg, whereas E/A less than 0.7 was predictive of pulmonary artery occlusion pressure less than 18 mm Hg with a sensitivity of 19% and a specificity of 94%. A similar predictive capacity was observed when the analysis was confined to patients with EF less than 50%. A large proportion of E/E' measurements 32 (60%) were situated between the two cut-off values obtained by the receiver operating characteristic curves: E/E' greater than 15 and E/E' less than 7. CONCLUSIONS: In mechanically ventilated critically ill patients, Doppler transthoracic echocardiography indices are highly specific but not sensitive to estimate pulmonary artery occlusion pressure.

Estimation of Pulmonary Artery Occlusion Pressure Using Doppler Echocardiography in Mechanically Ventilated Patients.

OBJECTIVES: Evaluation of left atrial pressure is frequently required for mechanically ventilated critically ill patients. The objective of the present study was to evaluate the 2016 American Society of Echocardiography and the European Association of Cardiovascular Imaging guidelines for assessment of the pulmonary artery occlusion pressure (a frequent surrogate of left atrial pressure) in this population. DESIGN: A pooled analysis of three prospective cohorts of patients simultaneously assessed with a pulmonary artery catheter and echocardiography. SETTINGS: Medical-surgical intensive care department of two university hospitals in France. PATIENTS: Mechanically ventilated critically ill patients. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Of 98 included patients (males: 67%; mean ± SD age: 59 ± 16; and mean Simplified Acute Physiology Score 2: 54 ± 20), 53 (54%) experienced septic shock. Using the 2016 American Society of Echocardiography and the European Association of Cardiovascular Imaging guidelines, the predicted pulmonary artery occlusion pressure was indeterminate in 48 of the 98 patients (49%). Of the 24 patients with an elevated predicted left atrial pressure (grade II/III diastolic dysfunction), only 17 (71%) had a pulmonary artery occlusion pressure greater than or equal to 18 mm Hg. Similarly, 20 of the 26 patients (77%) with a normal predicted left atrial pressure (grade I diastolic dysfunction) had a measured pulmonary artery occlusion pressure less than 18 mm Hg. The sensitivity and specificity of American Society of Echocardiography and the European Association of Cardiovascular Imaging guidelines for predicting elevated pulmonary artery occlusion pressure were both 74%. The agreement between echocardiography and the pulmonary artery catheter was moderate (Cohen's Kappa, 0.48; 95% CI, 0.39-0.70). In a proposed alternative algorithm, the best echocardiographic predictors of a normal pulmonary artery occlusion pressure were a lateral e'-wave greater than 8 (for a left ventricular ejection fraction ≥ 45%) or an E/A ratio less than or equal to 1.5 (for a left ventricular ejection fraction < 45%). CONCLUSIONS: The American Society of Echocardiography and the European Association of Cardiovascular Imaging guidelines do not accurately assess pulmonary artery occlusion pressure in ventilated critically ill patients. Simple Doppler measurements gave a similar level of diagnostic performance with less uncertainly.

The predictability of dynamic preload indices depends on the volume of fluid challenge: A prospective observational study in the operating theater.

This study was designed to assess the association between volume of fluid challenge (FC) and predictability of respiratory variation of stroke volume (ΔrespSV) in the operating theater.Patients undergoing intermediate/high-risk surgery and monitored by esophageal Doppler monitoring (EDM) were prospectively included. All patients were under general anesthesia and mechanically ventilated. Exclusion criteria were frequent ectopic beats or preoperative arrhythmia, right ventricular failure, and spontaneous breathing. Hemodynamic parameters and esophageal Doppler indices (SV, cardiac output, ΔrespSV) were collected before, after infusion of 250 mL, and after infusion of 500 mL of crystalloid solution. Responders were defined by a >15% increase of stroke volume after FC at each step.After infusion of a 250 mL FC, 41 patients (32%) were classified as fluid responders (R250). After infusion of a 500 mL FC, 80 patients (63%) were classified as fluid responders (R500). The predictability of ΔrespSV was fair with an area under the curve (AUC) of 0.79 (95% CI 0.71-0.86, P < .001) to predict fluid responsiveness with a 250 mL FC. With an AUC of 0.94 (95% CI 0.88-0.97, P < .0001), ΔrespSV presented an excellent ability to predict fluid responsiveness with a 500-mL FC.Predictability of ΔrespSV changed with the volume of fluid infused to assess fluid responsiveness. The accuracy of ΔrespSV was higher with 500 mL than with 250 mL. Bedside studies evaluating the predictability of dynamic preload indices should define fluid responsiveness as a >15% increase of SV in response to a 500-mL FC.

The Warburg Effect as a Type B Lactic Acidosis in a Patient With Acute Myeloid Leukemia: A Diagnostic Challenge for Clinicians.

INTRODUCTION: The Warburg effect (WE) is an uncommon cause of type B lactic acidosis (LA) due to a deregulation of carbohydrate metabolism in neoplastic cells where lactic fermentation predominates over oxidative phosphorylation regardless of the oxygen level. CASE PRESENTATION: We report the case of a 57-year-old man presenting with concomitant acute myeloid leukemia and type B LA with asymptomatic hypoglycemia. We did not find arguments for a septic state, liver dysfunction, or acute mesenteric ischemia. The WE was suspected, and chemotherapy was immediately undertaken. We observed a rapid and sustained decrease in lactate level and normalization of blood glucose. Unfortunately, we noted a relapse of acute leukemia associated with WE soon after treatment initiation and the patient died in the Intensive Care unit. DISCUSSION: Some patients may present complications directly related to an underlying hematological malignancy. The WE is one of these complications and should be suspected in patients with both hypoglycemia and LA. We propose a checklist in order to help clinicians manage this life-threatening complication. Before considering WE, clinicians should eliminate diagnoses such as septic shock or mesenteric ischemia, which require urgent and specific management. CONCLUSION: The diagnosis of WE can be challenging for clinicians in the Hematology department and the Intensive Care unit. Prompt diagnosis and rapid, adapted chemotherapy initiation may benefit patient survival.

Stroke volume changes induced by a recruitment maneuver predict fluid responsiveness in patients with protective ventilation in the operating theater.

During abdominal surgery, the use of protective ventilation with a low tidal volume, positive expiratory pressure (PEEP) and recruitment maneuvers (RMs) may limit the applicability of dynamic preload indices. The objective of the present study was to establish whether or not the variation in stroke volume (SV) during an RM could predict fluid responsiveness.We prospectively included patients receiving protective ventilation (tidal volume: 6 mL kg, PEEP: 5-7 cmH2O; RMs). Hemodynamic variables, such as heart rate, arterial pressure, SV, cardiac output (CO), respiratory variation in SV (ΔrespSV) and pulse pressure (ΔrespPP), and the variation in SV (ΔrecSV) as well as pulse pressure (ΔrecPP) during an RM were measured at baseline, at the end of the RM, and after fluid expansion. Responders were defined as patients with an SV increase of at least 15% after infusion of 500 mL of crystalloid solution.Thirty-seven (62%) of the 60 included patients were responders. Responders and nonresponders differed significantly in terms of the median ΔrecSV (26% [19-37] vs 10% [4-12], respectively; P < 0.0001). A ΔrecSV value more than 16% predicted fluid responsiveness with an area under the receiver-operating characteristic curve (AU) of 0.95 (95% confidence interval [CI]: 0.91-0.99; P < 0.0001) and a narrow gray zone between 15% and 17%. The area under the curve values for ΔrecPP and ΔrespSV were, respectively, 0.81 (95%CI: 0.7-0.91; P = 0.0001) and 0.80 (95%CI: 0.70-0.94; P < 0.0001). ΔrespPP did not predict fluid responsiveness.During abdominal surgery with protective ventilation, a ΔrecSV value more than 16% accurately predicted fluid responsiveness and had a narrow gray zone (between 15% and 17%). ΔrecPP and ΔrespSV (but not ΔrespPP) were also predictive.