Bedside echocardiographic evaluation of hemodynamics in sepsis: is a qualitative evaluation sufficient?

OBJECTIVE: Transesophageal echocardiography (TEE) has proven its efficiency in assessing hemodynamics in patients by its ability to evaluate cardiac function and fluid responsiveness. Classically, it requires quantitative measurements, whereas in routine practice TEE is used in our unit especially as a qualitative procedure. We assessed the accuracy of this qualitative central hemodynamic evaluation obtained by TEE at the bedside. DESIGN AND SETTING: Prospective study conducted in a medical ICU between September 2004 and April 2005. All TEE examinations performed in consecutive patients hospitalized for septic shock and mechanically ventilated for an associated acute lung injury were eligible for evaluation. Intensivists trained in echocardiography were asked to classify (a) respiratory changes in the superior vena cava (SVC), (b) left ventricular (LV) systolic function, (c) right ventricular (RV) end-diastolic size, and (d) shape and kinetics of the interventricular septum (IVS). A post-hoc quantitative evaluation was then performed by a trained investigator unaware of the patients' status. RESULTS: We evaluated 83 examinations in 30 patients. Qualitative evaluation was easily able to distinguish patients with significant or nonsignificant SVC respiratory changes, normal, moderately or markedly depressed LV systolic function, and nondilated or dilated right ventricle. Acute cor pulmonale was also well recognized. CONCLUSION: By its ability accurately to evaluate hemodynamic status qualitative TEE could be useful for intensivists in managing circulatory failure in septic shock, rendering the more time-consuming quantitative evaluation useless.

Incidence, causes and prognosis of hypotension related to meprobamate poisoning.

OBJECTIVE: Meprobamate self-poisoning has been reported as potentially inducing hypotension. We examined the incidence and causes of hypotension induced by this poisoning and its prognosis. DESIGN AND SETTING: Retrospective observational study conducted in a medical ICU between June 1997 and October 2003. Seventy-four patients admitted for meprobamate poisoning and needing mechanical ventilation were included. Demographic, clinical, and laboratory data were compared between patients with and without hypotension. All echocardiograms recorded in patients with hypotension were reviewed, and left ventricular (LV) and right ventricular (RV) functions were assessed. RESULTS: Twenty-nine (40%) patients exhibited hypotension without any significant difference in age, gender, cardiac history, or meprobamate concentration in blood when compared to patients without hypotension. Base excess was significantly lower in patients with hypotension. Echocardiography demonstrated a hypokinetic state, associating decreased LV ejection fraction (45+/-15%) and cardiac index (2+/-0.7 l min(-1) m(-2)), and increased inferior vena cava diameter. Most patients with hypotension received inotropic drugs by infusion, and were ventilated for significantly longer. CONCLUSIONS: Meprobamate self-poisoning induces hypotension, notably related to cardiac failure, in about 40% of cases. This has important therapeutic consequences, as frequent inotropic drug infusion. The mechanisms of cardiac toxicity remain largely unknown, and no predictive factor could be isolated.

Early veno-venous haemodiafiltration for sepsis-related multiple organ failure.

INTRODUCTION: We conducted a prospective observational study from January 1995 to December 2004 to evaluate the impact on recovery of a major advance in renal replacement therapy, namely continuous veno-venous haemodiafiltration (CVVHDF), in patients with refractory septic shock. METHOD: CVVHDF was implemented after 6-12 hours of maximal haemodynamic support, and base excess monitoring was used to evaluate the improvement achieved. Of the 60 patients studied, 40 had improved metabolic acidosis after 12 hours of CVVHDF, with a progressive improvement in all failing organs; the final mortality rate in this subgroup was 30%. In contrast, metabolic acidosis did not improve in the remaining 20 patients after 12 hours of CVVHDF, and the mortality rate in this subgroup was 100%. The crude mortality rate for the whole group was 53%, which is significantly lower than the predicted mortality using Simplified Acute Physiology Score II (79%). CONCLUSION: Early CVVHDF may improve the prognosis of sepsis-related multiple organ failure. Failure to correct metabolic acidosis rapidly during the procedure was a strong predictor of mortality.

Ability and safety of a heated humidifier to control hypercapnic acidosis in severe ARDS.

OBJECTIVE: To assess the ability of a heated humidifier to improve CO(2) clearance in ARDS patients submitted to protective ventilation. DESIGN: Prospective clinical study. SETTING: University hospital intensive care unit. PATIENTS: During a 12-month period, we studied 11 ARDS patients under protective mechanical ventilation with severe hypercapnia. INTERVENTION: When PaCO(2) was above 55 mmHg, the heat and moisture exchanger (HME) was removed and patients were ventilated using a heated humidifier (HH) until their recovery or death. The heated humidifier was inserted on the inspiratory limb of the respirator and the inspirated air was saturated to achieve a temperature of 40 degrees C at the Y connector of ventilator tubing and of 37 degrees C at the outlet of the endotracheal tube. MEASUREMENTS AND RESULTS: Mechanical measurements and blood gas analysis were performed just before removal of the HME, and 30 min after mechanical ventilation using HH. Ventilator parameters were kept constant in the two conditions. Using HH instead of HME, PaCO(2) was safely decreased by 11+/-5 mmHg, without any need to change respiratory rate. No significant difference was noted in intrinsic PEEP or airway plateau pressure. Decrease in PaCO(2) after HME removal was strongly correlated with the initial value of PaCO(2). CONCLUSION: Supposing there is an interest in correcting or limiting hypercapnic acidosis in ARDS patients submitted to protective ventilation, HME removal and use of HH appears to be an efficient and safe way of increasing CO(2) clearance.

Superior vena caval collapsibility as a gauge of volume status in ventilated septic patients.

OBJECTIVE: In mechanically ventilated patients inspiratory increase in pleural pressure during lung inflation may produce complete or partial collapse of the superior vena cava. Occurrence of this collapse suggests that at this time external pressure exerted by the thoracic cavity on the superior vena cava is greater than the venous pressure required to maintain the vessel fully open. We tested the hypothesis that measurement of superior vena caval collapsibility would reveal the need for volume expansion in a given septic patient. DESIGN AND SETTING: Prospective data collection for 66 successive patients in septic shock admitted in a medical intensive care unit and mechanically ventilated for an associated acute lung injury. MEASUREMENTS AND RESULTS: We simultaneously measured superior vena caval collapsibility by echocardiography and cardiac index by the Doppler technique at baseline and after a 10 ml/kg volume expansion by 6% hydroxyethyl starch in 30 min. The threshold superior vena caval collapsibility of 36%, calculated as (maximum diameter on expiration-minimum diameter on inspiration)/maximum diameter on expiration, allowed discrimination between responders (defined by an increase in cardiac index of at least 11% induced by volume expansion) and nonresponders, with a sensitivity of 90% and a specificity of 100%. CONCLUSIONS: Superior vena cava measurement should be systematically performed during routine echocardiography in septic shock as it gives an accurate index of fluid responsiveness.

Early patterns of static pressure-volume loops in ARDS and their relations with PEEP-induced recruitment.

OBJECTIVE: Evaluation of low-flow pressure-volume loop at the bedside in ARDS, as an aid to assess recruitment produced by PEEP. MATERIALS AND METHODS: Low-flow pressure-volume loop at the bedside were obtained on the first day of respiratory support in 54 successive pulmonary ARDS patients (49 of whom had pneumonia) treated between April 1999 and June 2002. From the loop obtained at ZEEP, we determined manually the lower inflexion point (LIP). By superimposing the pressure-volume loop at ZEEP and at PEEP, we evaluated recruitment obtained at a constant elastic pressure of 20 cm H2O. RESULTS: We observed two different types of loops, according to the pattern of the inflation limb. In type 1 (38 cases) the inflation limb was characterized by an inflexion zone, resulting from a progressive or a sudden improvement in compliance. In type 2 (16 patients) the inflation limb was virtually linear, without significant improvement in compliance during inflation, which remained particularly low (26+/-9 cm H2O). Use of a low PEEP (6+/-2 cm H2O) produced a substantial recruitment in type-1 patients (74+/-53 ml), which was marginally improved by a higher PEEP (89+/-54 ml). In type 2, recruitment produced by PEEP was significantly lower (48+/-26 ml, p=0.006). CONCLUSION: Pressure-volume loop at bedside confirmed that a low PEEP was sufficient to obtain recruitment in ARDS. This study also individualized a group of pulmonary ARDS patients exhibiting a markedly reduced compliance, in whom recruitment obtained by PEEP was limited.

Difficult peripheral venous access: clinical evaluation of a catheter inserted with the Seldinger method under ultrasound guidance.

PURPOSE: A preliminary observational study was undertaken to evaluate the risk of failure of ultrasound-guided peripheral intravenous catheterization of a deep arm vein for a maximum of 7 days, after peripheral intravenous (PIV) cannulation failure. METHODS: This prospective study included patients referred to the intensive care unit for placement of a central line, a polyurethane cannula commercialized for arterial catheterization was used for peripheral venous cannulation. Catheter length and diameter were chosen based on preliminary ultrasound measurements of vein diameter and skin-vein distance. RESULTS: Catheterization was successful for all 29 patients. Mean vein diameter was 0.42 ± 0.39 cm; mean vein depth was 0.94 ± 0.52 cm. Mean catheter duration was 6 (median 7) days. Two occluded catheters were removed prematurely. No thrombophlebitis, catheter infection, or extravasation was observed. CONCLUSION: Our results suggest that catheters inserted with the Seldinger method are adapted to prolonged peripheral deep-vein infusion. Ultrasound can play a role in catheter monitoring by identifying early thrombosis formation.

Evaluation of blind nasotracheal suctioning and non-bronchoscopic mini-bronchoalveolar lavage in critically ill patients with infectious pneumonia: a preliminary study.

BACKGROUND: We evaluated the diagnostic performance and safety of combined blind nasotracheal suctioning and non-bronchoscopic mini-bronchoalveolar lavage (mini-BAL) to obtain respiratory secretion specimens from spontaneously breathing, non-intubated patients with infectious pneumonia in intensive care. METHODS: Patients suspected of having infectious pneumonia were included prospectively. Three samples were obtained: expectorated sputum, nasotracheal suctioning, and mini-BAL via a double telescopic catheter (Combicath). Under local anesthesia, nasotracheal suctioning was done according to standard recommendations. Then mini-BAL was performed; the bronchial catheter serves as a guide for the mini-BAL catheter, and tracheal position is verified via colorimetric capnography. RESULTS: We included 36 subjects (29 men, median age 69 y, median Simplified Acute Physiology Score II 32), of which 32 (89%) underwent nasotracheal suctioning and mini-BAL, and from 13 (36%) we collected expectorated sputum. Based on colorimetric capnography confirmation of the tracheal position, 75% (24/32) of the successful combined procedures were achieved on the first attempt. The median duration of the combined procedure was 7 min. Bacterial pneumonia was diagnosed in 24/36 (67%) subjects, among whom 21 (88%) had undergone successful nasotracheal suctioning and mini-BAL, respectively, for 8/21 (38% [95% CI 0.17-0.58%] and 14/21 (67% [95% CI 0.46-0.86%]). Mini-BAL diagnosed a significantly higher percentage of bacterial pneumonias than did nasotracheal suctioning. Expectorated sputum yielded no diagnoses. CONCLUSIONS: Blind nasotracheal suctioning confirmed via colorimetric capnography allows microbiological diagnosis, and can be enhanced by non-bronchoscopic mini-BAL. Colorimetric capnography helps confirm bronchial tube position. Non-bronchoscopic mini-BAL is a novel and feasible way to collect bronchial secretions without fibroscopy. (ClinicalTrials.gov NCT00763620.).

Cyclic changes in arterial pulse during respiratory support revisited by Doppler echocardiography.

It has long been known that there are cyclic changes in arterial pressure during mechanical ventilation. They are caused by cyclic changes in both the right and left ventricular stroke output, occurring in opposite phases. As a result, arterial pulse pressure is increased during inspiration and decreased during expiration. A cyclic improvement in left ventricular systolic function could thus be expected during mechanical lung inflation. We tested this hypothesis in 31 septic patients who were mechanically ventilated in controlled mode by combining left ventricular measurements by transesophageal echocardiography with invasive arterial pressure recordings and Doppler analysis of pulmonary venous flow and right and left ventricular stroke volume. Lung inflation by tidal ventilation significantly improved left ventricular stroke volume (26 +/- 0.4 cm3/m2 [mean +/- SEM] vs. 22.3 +/- 0.4 cm3/m2 at end deflation). Beat-to-beat analysis of pulmonary venous flow velocity illustrated the boosting effect of lung inflation on pulmonary venous return. The beneficial effect of inspiration thus appeared directly related to a significant increase in left ventricular diastolic volume (60.3 +/- 1.5 cm3/m2 vs. 53.3 +/- 1.4 cm3/m2 at end-expiration) and to a lesser extent to an improved left ventricular ejection fraction. We concluded that the transient beneficial hemodynamic effect of tidal ventilation on the left ventricular pump is essentially mediated by an improved left ventricular filling.