Respiratory change in ECG-wave amplitude is a reliable parameter to estimate intravascular volume status.

Electrocardiogram (ECG) is a standard type of monitoring in intensive care medicine. Several studies suggest that changes in ECG morphology may reflect changes in volume status. The "Brody effect", a theoretical analysis of left ventricular (LV) chamber size influence on QRS-wave amplitude, is the key element of this phenomenon. It is characterised by an increase in QRS-wave amplitude that is induced by an increase in ventricular preload. This study investigated the influence of changes in intravascular volume status on respiratory variations of QRS-wave amplitudes (ΔECG) compared with respiratory pulse pressure variations (ΔPP), considered as a reference standard. In 17 pigs, ECG and arterial pressure were recorded. QRS-wave amplitude was measured from the Biopac recording to ensure that in all animals ECG electrodes were always at the same location. Maximal QRS amplitude (ECGmax) and minimal QRS amplitude (ECGmin) were determined over one respiratory cycle. ΔECG was calculated as 100 × [(ECGmax - ECGmin)/(ECGmax + ECGmin)/2]. ΔECG and ΔPP were simultaneously recorded. Measurements were performed at different time points: during normovolemic conditions, after haemorrhage (25 mL/kg), and following re-transfusion (25 mL/kg) with constant tidal volume (10 mL/kg) and respiration rate (15 breath/min). At baseline, ΔPP and ΔECG were both <12 %. ΔPP were significantly correlated with ΔECG (r(2) = 0.89, p < 0.001). Volume loss induced by haemorrhage increased significantly ΔPP and ΔECG. Moreover, during this state, ΔPP were significantly correlated with ΔECG (r(2) = 0.86, p < 0.001). Re-transfusion significantly decreased ΔPP and ΔECG, and ΔPP were significantly correlated with ΔECG (r(2) = 0.90, p < 0.001). The observed correlations between ΔPP and ΔECG at each time point of the study suggest that ΔECG is a reliable parameter to estimate the changes in intravascular volume status and provide experimental confirmation of the "Brody effect."

Autoinducer production and quorum-sensing dependent phenotypes of Pseudomonas aeruginosa vary according to isolation site during colonization of intubated patients.

BACKGROUND: Pseudomonas aeruginosa frequently colonizes and is responsible for severe ventilator-associated pneumonia in intubated patients. A quorum-sensing (QS) circuit, depending on the production of the two QS-signaling molecules (autoinducers, AIs) 3-oxo-C12-HSL and C4-HSL, regulates the production by P. aeruginosa of several virulence factors and is required for biofilm formation. Therefore QS-inhibition has been suggested as a new target for preventive and/or therapeutic strategies. However the precise role of QS during colonization and subsequent infections of intubated patients remains unclear. RESULTS: We wondered whether QS is active during colonization of intubated patients, and whether P. aeruginosa isolates growing inside the biofilm covering the intubation devices and those resident in the lungs of colonized patients differ in their QS-dependent phenotypes. We collected the intubation devices of eight patients colonized by P. aeruginosa. We detected 3-oxo-C12-HSL on eight, and C4-HSL on six of these devices. In three of these patients we also obtained P. aeruginosa isolates from tracheal aspirates at the time of extubation (n = 18), as well as isolates from the intubation devices (n = 25). We genotyped these isolates, quantified their AIs production, and determined three QS-dependent phenotypes (adherence capacity, biofilm and elastase production). The production of 3-oxo-C12-HSL was consistently increased for isolates from the intubation devices, whereas the production of C4-HSL was significantly higher for isolates from tracheal aspirates. Isolates from tracheal aspirates produced significantly higher amounts of elastase but less biofilm, and had a marginally reduced adhesion capacity than isolates from the intubation devices. Levels of 3-oxo-C12-HSL and elastase production correlated statistically for tracheal intubation isolates, whereas levels of 3-oxo-C12-HSL production and adhesion ability, as well as biofilm production, correlated weakly amongst intubation device isolates. CONCLUSION: Our findings demonstrate that autoinducers are produced during the colonization of intubated patients by P. aeruginosa. The microenvironment, in which P. aeruginosa grows, may select for bacteria with different capacities to produce autoinducers and certain QS-dependent phenotypes. QS-inhibition might therefore affect differently isolates growing inside the biofilm covering intubation devices and those resident in the lungs.

Does continuous positive airway pressure by face mask improve patients with acute cardiogenic pulmonary edema due to left ventricular diastolic dysfunction?

OBJECTIVE: Continuous positive airway pressure (CPAP) by face mask is an effective method of treating severe cardiogenic pulmonary edema (CPE). However, to our knowledge, no study has provided a precise evaluation of the effects of CPAP on cardiac function in patients presenting with CPE and preserved left ventricular (LV) function. DESIGN: Prospective observational clinical study. SETTING: A 14-bed, medical ICU at a university hospital. PATIENTS: Nine consecutive patients presenting with hypoxemic acute CPE. INTERVENTIONS: All patients were selected for 30 min of CPAP with 10 cm H(2)O by mask with fraction of inspired oxygen adjusted for a cutaneous saturation > 90%. Doppler echocardiography was performed before CPAP application and during the last 10 min of breathing with CPAP. Two-tailed, paired t-tests were used to compare data recorded at baseline (oxygen alone) and after CPAP. MEASUREMENTS AND RESULTS: Four patients presented CPE with preserved left ventricular (LV) function (a preserved LV ejection fraction [LVEF] > 45%, and/or aortic velocity time integral > 17 cm in the absence of aortic stenosis or hypertrophic cardiomyopathy). Oxygenation and ventilatory parameters were improved by CPAP in all patients. Hemodynamic monitoring and Doppler echocardiographic analysis demonstrated that in patients with preserved LV systolic function, mean arterial pressure and LV end-diastolic volume were decreased significantly by CPAP (p < 0.04). In patients with LV systolic dysfunction, CPAP improved LVEF (p < 0.05) and decreased LV end-diastolic volume (p = 0.001) significantly. CONCLUSION: CPAP improves oxygenation and ventilatory parameters in all kinds of CPE. In patients with preserved LV contractility, the hemodynamic benefit of CPAP results from a decrease in LV end-diastolic volume (preload).

Inappropriate initial antimicrobial therapy and its effect on survival in a clinical trial of immunomodulating therapy for severe sepsis.

PURPOSE: To examine the effect of inappropriate initial antimicrobial therapy on the prognosis of patients with sepsis who were enrolled in a clinical trial of an immunomodulating agent conducted in 108 hospitals in North America and Europe. METHODS: We assessed initial antimicrobial choice and results of microbiologic cultures in 904 patients who had microbiologically confirmed severe sepsis or early septic shock. If a patient did not receive at least one antimicrobial agent to which the causative microorganisms were susceptible within 24 hours from the diagnosis of severe sepsis, then the initial antimicrobial treatment was considered to be inappropriate. A propensity score that adjusted for factors associated with inappropriate antimicrobial treatment was calculated and included in multivariable models to adjust for confounding. RESULTS: A total of 468 patients (52%) had documented bloodstream infection, and 211 patients (23%) received inappropriate initial antimicrobial therapy. Characteristics associated with inappropriate treatment were study enrollment in Europe, admission to surgery, nosocomial infection, infection with multiresistant microorganisms, and fungal or polymicrobial infection (all P <0.05). The 28-day mortality was 24% (168/693) for patients in the adequately treated group versus 39% (82/211) for patients receiving inappropriate initial antimicrobial therapy (P <0.001). After adjusting for comorbid conditions, severity of illness, site of infection, and the propensity score, inappropriate antimicrobial therapy was independently associated with increased mortality (odds ratio = 1.8; 95% confidence interval: 1.2 to 2.6). CONCLUSION: In a large cohort of patients with microbiologically confirmed severe sepsis, appropriate initial antimicrobial therapy was an important determinant of survival. New approaches aimed at improving detection and treatment of early sepsis are needed.

Four-year follow-up of body compostion in lung transplant patients.

BACKGROUND: Both undernutrition and overnutrition can affect the quality of life and survival of patients with pulmonary disease and lead to quantitative and functional alterations of fat-free mass (FFM). This longitudinal study determines the changes in weight, FFM, and body fat before and up to 4 years after lung transplant (LTR). METHODS: Height, weight, and body composition measurements (bioelectrical impedance) were obtained in 37 LTR patients. FFM and body fat were measured before and at 1, 3, 6, 9, 12, 18, 24, 36, and 48 months after LTR. RESULTS: Weight changed by +16.6%, +3.2%, -0.2%, and -3.2% and FFM by +14.0%, +2.5%, -0.3%, and -1.0% during years 1, 2, 3, and 4, respectively. A diagnosis of obliterative bronchiolitis after LTR was associated with loss of body weight, FFM, and body fat, compared with stable weight or gain in weight, FFM, and body fat in obliterative bronchiolitis-negative subjects; 76.2% and 85.7%, and 28% and 38% of men and women, respectively, demonstrated low FFM at 1 month and at 2 years after LTR, respectively. The FFM change was higher (39% of weight) during year 1 than during year 2 (25%) or year 3 (21%). CONCLUSIONS: After LTR, patients gained weight, FFM, and body fat, and two-thirds reached normal levels of FFM by year 2. A weight increase resulted in an FFM increase. Contrary to studies after heart or liver transplantation, our results suggest that despite posttransplant infections and grafts rejection, LTR permits FFM recovery.

Fluid responsiveness in mechanically ventilated patients: a review of indices used in intensive care.

OBJECTIVE: In mechanically ventilated patients the indices which assess preload are used with increasing frequency to predict the hemodynamic response to volume expansion. We discuss the clinical utility and accuracy of some indices which were tested as bedside indicators of preload reserve and fluid responsiveness in hypotensive patients under positive pressure ventilation. RESULTS AND CONCLUSIONS: Although preload assessment can be obtained with fair accuracy, the clinical utility of volume responsiveness-guided fluid therapy still needs to be demonstrated. Indeed, it is still not clear whether any form of monitoring-guided fluid therapy improves survival.

Prevention of severe Candida infections in nonneutropenic, high-risk, critically ill patients: a randomized, double-blind, placebo-controlled trial in patients treated by selective digestive decontamination.

OBJECTIVE: Infections caused by Candida spp. are a major cause of morbidity and mortality in critically ill patients and usually develop from endogenous colonization. We assessed the effectiveness of adding fluconazole to a selective digestive decontamination regimen to prevent candidal infections. DESIGN AND SETTING: We performed a prospective, randomized, double-blind, placebo-controlled trial among medical and surgical intensive care unit patients at a large university hospital. PATIENTS: All adult patients mechanically ventilated for at least 48 h with an expectation to remain so for at least an additional 72 h, and receiving selective decontamination of the digestive tract. INTERVENTIONS: Patients were randomly assigned fluconazole 100 mg daily (n=103) or placebo (n=101). MEASUREMENTS AND RESULTS: Candida infections occurred less frequently in the fluconazole group (5.8%) than in the placebo group (16%; rate ratio 0.35; Cl(95) 0.11-0.94). Some 90% of candidemia episodes occurred in the placebo group (rate ratio for fluconazole use 0.10; Cl(95) 0.02-0.74). The rate of treatment failure, development of candidal infection, or increased colonization, was 32% in the fluconazole group and 67% in the placebo group (P<0.001). Crude in-hospital mortality was similar in the two groups (39% fluconazole vs. 41% placebo). CONCLUSIONS: Prophylactic use of fluconazole in a selected group of mechanically ventilated patients at high risk for infection reduces the incidence of Candida infections, in particular candidemia.

The respiratory change in preejection period: a new method to predict fluid responsiveness.

The accuracy and clinical utility of preload indexes as bedside indicators of fluid responsiveness in patients after cardiac surgery is controversial. This study evaluates whether respiratory changes (Delta) in the preejection period (PEP; DeltaPEP) predict fluid responsiveness in mechanically ventilated patients. Sixteen postcoronary artery bypass surgery patients, deeply sedated under mechanical ventilation, were enrolled. PEP was defined as the time interval between the beginning of the Q wave on the electrocardiogram and the upstroke of the radial arterial pressure. DeltaPEP (%) was defined as the difference between expiratory and inspiratory PEP measured over one respiratory cycle. We also measured cardiac output, stroke volume index, right atrial pressure, pulmonary arterial occlusion pressure, respiratory change in pulse pressure, systolic pressure variation, and the Deltadown component of SPV. Data were measured without positive end-expiratory pressure (PEEP) and after application of a PEEP of 10 cmH2O (PEEP10). When PEEP10 induced a decrease of >15% in mean arterial pressure value, then measurements were re-performed before and after volume expansion. Volume loading was done in eight patients. Right atrial pressure and pulmonary arterial occlusion pressure before volume expansion did not correlate with the change in stroke volume index after the fluid challenge. Systolic pressure variation, DeltaPEP, Deltadown, and change in pulse pressure before volume expansion correlated with stroke volume index change after fluid challenge (r2 = 0.52, 0.57, 0.68, and 0.83, respectively). In deeply sedated, mechanically ventilated patients after cardiac surgery, DeltaPEP, a new method, can be used to predict fluid responsiveness and hemodynamic response to PEEP10.

Correlation between measured inferior vena cava diameter and right atrial pressure depends on the echocardiographic method used in patients who are mechanically ventilated.

In patients who are mechanically ventilated, the correlation between inferior vena cava diameter (IVCD) measurements and mean right atrial pressure (RAP) varies in the literature. The purpose of this study was to test if the correlation between IVCD and RAP measurement in patients who are critically ill depends on the transthoracic echocardiography (TTE) methodology used. Twenty patients who were critically ill, sedated, and required respiratory support were prospectively studied by TTE during mechanical ventilation in a controlled mode. The TTE measures of IVCD were made, using methods previously cited. First, IVCD was measured at end-expiration and end-diastole, with ECG synchronization, using the M-mode, on short-axis view 2 cm below the right atrium. Second, IVCD was assessed at end-expiration, without ECG synchronization, using the 2-dimensional long-axis view at the same location. RAP was measured simultaneously by using a central venous catheter positioned in the superior vena cava. All measurements were taken in the supine position. IVCD at end-expiration and end-diastole, with ECG synchronization, using the M-mode, and IVCD at end-expiration, without ECG synchronization, using the 2-dimensional long-axis view, correlate linearly with RAP (0.81, P <.0001 and 0.71, P =.0004). Mean bias between the 2 TTE methods (Bland-Altman analysis) was 1.6 mm (SD +/- 2.03 mm). In conclusion, this study confirms that variation of correlation between TTE IVCD measurement and RAP depends on the ultrasonographic methodology used and the timing of measurement during the cardiac cycle. IVCD at end-expiration and end-diastole, with ECG synchronization, using the M-mode (IVCD-MM) correlates more satisfactory with RAP than with IVCD at end-expiration, without ECG synchronization, using the 2-dimensional long-axis view, in patients during mechanical ventilation.

[Continuous Svo2 measurements and co-oximetry are not interchangeable immediately after cardiopulmonary bypass]. / Après circulation extra-corporelle, la mesure continue de la Svo2 et la co-oxymétrie du sang mêlé ne sont pas interchangeables.

OBJECTIVE: To determine the accuracy of continuous (in vivo) measurement of mixed venous oxygen saturation (SvO(2)), using a fibreoptic catheter, in patients having had cardiopulmonary bypass (CPB). METHODS: Using a pulmonary arterial catheter, we prospectively studied 14 patients (age 64 +/- 8) having had cardiopulmonary bypass. Mean hematocrit was 30 +/- 4%. The catheter was calibrated in vitro and in vivo, according to the manufacturer's instructions. Fifty-six simultaneous measurements of continuous SvO(2) (CSvO(2)) and measured SvO(2) (MSvO(2)) were taken with a co-oxymeter and the paired values were analyzed by the linear regression method. To make the two sets of measurements interchangeable, we established, a priori, a maximum limit of 3% (approximately 5% of the measurement), as being an acceptable difference between the two types of measurements. RESULTS: All the measurements were obtained within four hours of the placement of the catheter. CSvO(2) was weakly correlated with MSvO(2), with a correlation coefficient of r(2) = 0.49 (P < 0.001). The Bland-Altman analysis demonstrates an objective mean bias of 0.8 +/- 3%, with 36% of the values measured falling outside clinically acceptable limits. For values of CSvO(2)