Myocardial Function during Low versus Intermediate Tidal Volume Ventilation in Patients without Acute Respiratory Distress Syndrome.

BACKGROUND: Mechanical ventilation with low tidal volumes has the potential to mitigate ventilation-induced lung injury, yet the clinical effect of tidal volume size on myocardial function has not been clarified. This cross-sectional study investigated whether low tidal volume ventilation has beneficial effects on myocardial systolic and diastolic function compared to intermediate tidal volume ventilation. METHODS: Forty-two mechanically ventilated patients without acute respiratory distress syndrome (ARDS) underwent transthoracic echocardiography after more than 24 h of mechanical ventilation according to the Protective Ventilation in Patients without ARDS (PReVENT) trial comparing a low versus intermediate tidal volume strategy. The primary outcome was left ventricular and right ventricular myocardial performance index as measure for combined systolic and diastolic function, with lower values indicating better myocardial function and a right ventricular myocardial performance index greater than 0.54 regarded as the abnormality threshold. Secondary outcomes included specific systolic and diastolic parameters. RESULTS: One patient was excluded due to insufficient acoustic windows, leaving 21 patients receiving low tidal volumes with a tidal volume size (mean ± SD) of 6.5 ± 1.8 ml/kg predicted body weight, while 20 patients were subjected to intermediate tidal volumes receiving a tidal volume size of 9.5 ± 1.6 ml/kg predicted body weight (mean difference, -3.0 ml/kg; 95% CI, -4.1 to -2.0; P < 0.001). Right ventricular dysfunction was reduced in the low tidal volume group compared to the intermediate tidal volume group (myocardial performance index, 0.41 ± 0.13 vs. 0.64 ± 0.15; mean difference, -0.23; 95% CI, -0.32 to -0.14; P < 0.001) as was left ventricular dysfunction (myocardial performance index, 0.50 ± 0.17 vs. 0.63 ± 0.19; mean difference, -0.13; 95% CI, -0.24 to -0.01; P = 0.030). Similarly, most systolic parameters were superior in the low tidal volume group compared to the intermediate tidal volume group, yet diastolic parameters did not differ between both groups. CONCLUSIONS: In patients without ARDS, intermediate tidal volume ventilation decreased left ventricular and right ventricular systolic function compared to low tidal volume ventilation, although without an effect on diastolic function.

Impact of Positive End-Expiratory Pressure on Thermodilution-Derived Right Ventricular Parameters in Mechanically Ventilated Critically Ill Patients.

OBJECTIVES: To examine the effect of positive end-expiratory pressure (PEEP) on right ventricular stroke volume variation (SVV), with possible implications for the number and timing of pulmonary artery catheter thermodilution measurements. DESIGN: Prospective, clinical pilot study. SETTING: Academic medical center. PARTICIPANTS: Patients who underwent volume-controlled mechanical ventilation and had a pulmonary artery catheter. INTERVENTION: PEEP was increased from 5-to-10 cmH2O and from 10-to-15 cmH2O with 10-minute intervals, with similar decreases in PEEP, from 15-to-10 cmH2O and 10-to-5 cmH2O. MEASUREMENTS AND MAIN RESULTS: In 15 patients, right ventricular parameters were measured using thermodilution at 10% intervals of the ventilatory cycle at each PEEP level with a rapid-response thermistor. Mean right ventricular stroke volume and end-diastolic volume declined during incremental PEEP and normalized on return to 5 cmH2O PEEP (p = 0.01 and p = 0.001, respectively). Right ventricular SVV remained unaltered by changes in PEEP (p = 0.26), regardless of incremental PEEP (p = 0.15) or decreased PEEP (p = 0.12). The coefficients of variation in the ventilatory cycle of all other thermodilution-derived right ventricular parameters also were unaffected by changes in PEEP. CONCLUSIONS: This study showed that increases in PEEP did not affect right ventricular SVV in critically ill patients undergoing mechanical ventilation despite reductions in mean right ventricular stroke volume and end-diastolic volume. This could be explained by cyclic counteracting changes in right ventricular preloading and afterloading during the ventilatory cycle, independent of PEEP. Changes in PEEP did not affect the number and timing of pulmonary artery catheter thermodilution measurements.

Safety and efficacy of amphotericin-B deoxycholate inhalation in critically ill patients with respiratory Candida spp. colonization: a retrospective analysis.

BACKGROUND: Candida spp. are frequently cultured from the respiratory tract in critically ill patients. Most intensivists start amphotericin-B deoxycholate (ABDC) inhalation therapy to eradicate Candida spp. from the respiratory tract. However, the safety and efficacy of this treatment are not well established. The purpose of this study was to assess the safety and efficacy of ABDC inhalation for the treatment of respiratory Candida spp. colonization in critically ill patients. METHODS: All non-neutropenic patients admitted into the intensive care unit (ICU) of a university hospital from December 2010-2011, who had positive Candida spp. cultures of the respiratory tract for more than 1 day and required mechanical ventilation >48 h were retrospectively included. The decision to start ABDC inhalation had been made by attending intensivists on clinical grounds in the context of selective decontamination of the digestive tract. Infection characteristics and patient courses were assessed. RESULTS: Hundred and thirteen consecutive patients were studied. Fifty-one of them received ABDC inhalation and their characteristics at baseline and day 1 of respiratory colonization did not differ from those of colonized patients not receiving treatment (n = 62). The ABDC-treated group had a similar Candida spp. load but did not decolonize more rapidly as compared to untreated patients. The clinical pulmonary infection and lung injury scores did not decrease as in the untreated group. In a Cox proportional hazard model, the duration of mechanical ventilation was increased (P < 0.003) by ABDC treatment independently of other potential determinants and Candida spp. colonization. No differences in ventilator-associated pneumonia or in overall mortality (up to day 90) were observed. CONCLUSION: Treatment of respiratory Candida spp. colonization in non-neutropenic critically ill patients by inhaled ABDC may not affect respiratory colonization but may increase duration of mechanical ventilation, because of direct toxicity of the drug on the lung.

Pulse pressure variation does not reflect stroke volume variation in mechanically ventilated rats with lipopolysaccharide-induced pneumonia.

1. The present study examined the relationship between centrally measured stroke volume variation (SVV) and peripherally derived pulse pressure variation (PPV) in the setting of increased total arterial compliance (CA rt ). 2. Ten male Wistar rats were anaesthetized, paralysed and mechanically ventilated before being randomized to receive intrapulmonary lipopolysaccharide (LPS) or no LPS. Pulse pressure (PP) was derived from the left carotid artery, whereas stroke volume (SV) was measured directly in the left ventricle. Values of SVV and PPV were calculated over three breaths. Balloon inflation of a catheter positioned in the inferior vena cava was used, for a maximum of 30 s, to decrease preload while the SVV and PPV measurements were repeated. Values of CA rt were calculated as SV/PP. 3. Intrapulmonary LPS increased CA rt and SV. Values of SVV and PPV increased in both LPS-treated and untreated rats during balloon inflation. There was a correlation between SVV and PPV in untreated rats before (r = 0.55; P = 0.005) and during (r = 0.69; P < 0.001) occlusion of the vena cava. There was no such correlation in LPS-treated rats either before (r = -0.08; P = 0.70) or during (r = 0.36; P = 0.08) vena cava occlusion. 4. In conclusion, under normovolaemic and hypovolaemic conditions, PPV does not reflect SVV during an increase in CA rt following LPS-induced pneumonia in mechanically ventilated rats. Our data caution against their interchangeability in human sepsis.

Plasma NGAL similarly predicts acute kidney injury in sepsis and nonsepsis.

AIM: Plasma NGAL is released in sepsis irrespective of acute kidney injury (AKI). The current study investigated the effect of sepsis on the diagnostic value of NGAL for AKI. MATERIALS & METHODS: In 700 intensive care unit admissions, NGAL was measured at four time points (<24 h) following admission. RESULTS: In total, 663 admissions were included in the final analysis, of which 80 patients had sepsis (12%). AKI occurred in 22% of the patients without and 66% with sepsis. NGAL levels were higher in non-AKI patients with sepsis compared with non-AKI patients without sepsis at all time points (p = 0.03 or lower). In patients with AKI a similar difference was observed (p < 0.001). The area under the curve for AKI was unaffected by the presence of sepsis (0.76 in sepsis vs 0.78 in nonsepsis; p = 0.72); however, the optimal test cutoff values were higher in the former. CONCLUSION: Sepsis enhances the production of plasma NGAL in critically ill adult patients irrespective of the presence of AKI. However, the diagnostic test accuracy for AKI is unaffected by sepsis, although optimal cutoff values are elevated.

Predicting outcome of rethoracotomy for suspected pericardial tamponade following cardio-thoracic surgery in the intensive care unit.

OBJECTIVES: Pericardial tamponade after cardiac surgery is difficult to diagnose, thereby rendering timing of rethoracotomy hard. We aimed at identifying factors predicting the outcome of surgery for suspected tamponade after cardio-thoracic surgery, in the intensive care unit (ICU). METHODS: Twenty-one consecutive patients undergoing rethoracotomy for suspected pericardial tamponade in the ICU, admitted after primary cardio-thoracic surgery, were identified for this retrospective study. We compared patients with or without a decrease in severe haemodynamic compromise after rethoracotomy, according to the cardiovascular component of the sequential organ failure assessment (SOFA) score. RESULTS: A favourable haemodynamic response to rethoracotomy was observed in 11 (52%) of patients and characterized by an increase in cardiac output, and less fluid and norepinephrine requirements. Prior to surgery, the absence of treatment by heparin, a minimum cardiac index < 1.0 L/min/m2 and a positive fluid balance (> 4,683 mL) were predictive of a beneficial haemodynamic response. During surgery, the evacuation of clots and > 500 mL of pericardial fluid was associated with a beneficial haemodynamic response. Echocardiographic parameters were of limited help in predicting the postoperative course, even though 9 of 13 pericardial clots found at surgery were detected preoperatively. CONCLUSION: Clots and fluids in the pericardial space causing regional tamponade and responding to surgical evacuation after primary cardio-thoracic surgery, are difficult to diagnose preoperatively, by clinical, haemodynamic and even echocardiographic evaluation in the ICU. Only absence of heparin treatment, a large positive fluid balance and low cardiac index predicted a favourable haemodynamic response to rethoracotomy. These data might help in deciding and timing of reinterventions after primary cardio-thoracic surgery.

Cardiac output derived from arterial pressure waveform analysis without calibration vs. thermodilution in septic shock: evolving accuracy of software versions.

BACKGROUND AND OBJECTIVE: We studied the evolution of software in the accuracy of the FloTrac/Vigileo system to measure cardiac output less invasively from arterial pressure waveform analysis without calibration, in comparison with pulmonary artery catheter-derived thermodilution measurements, in patients with septic shock and presumed alterations in vascular tone. METHODS: Nine patients who received a pulmonary artery catheter and were on mechanical ventilation and in sinus rhythm were monitored by the FloTrac/Vigileo. Paired cardiac output measurements by both techniques were analysed for 86 measurements in four patients using the 1.07 software version and 73 measurements in five subsequent patients using the later 1.10 version. RESULTS: For the 1.07 version, bias was -1.6 L min, precision 1.6 L min, limits of agreement -4.8-1.5 L min and error 48%. Measurements correlated at partial r equal to 0.32 (P = 0.003). For the 1.10 version, bias was -1.2 L min, precision 1.1 L min, limits of agreement -3.5-1.0 L min and error 32%. Measurements correlated at partial r equal to 0.90 (P < 0.001 vs. version 1.07). Differences were inversely related to mean cardiac output (P < 0.001, generalized estimating equations), particularly for software version 1.07 vs. 1.10 (P = 0.017, generalized estimating equation). Changes in thermodilution cardiac output over the course of time were also better tracked by the FloTrac/Vigileo when applying the latest software (P < 0.001, generalized estimating equation). CONCLUSIONS: Evolving software versions are thus better able to account for the effect of vascular tone on cardiac output measurements by less invasive waveform analyses without calibration (FloTrac/Vigileo), so that the latter may become useful in the haemodynamic monitoring of septic shock.