Respiratory pulse pressure variation fails to predict fluid responsiveness in acute respiratory distress syndrome (original) (raw)
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The assessment of transpulmonary pressure in mechanically ventilated ARDS patients
Intensive Care Medicine, 2014
Take-home message: The end-inspiratory transpulmonary pressure can be accurately computed by the elastance-derived method which, compared to the release method, avoids the risk of ventilator disconnection, while the directly measured end-expiratory transpulmonary pressure is not related to the release-derived transpulmonary pressure.
An Objective Analysis of the Pressure-Volume Curve in the Acute Respiratory Distress Syndrome
American Journal of Respiratory and Critical Care Medicine, 2000
To assess the interobserver and intraobserver variability in the clinical evaluation of the quasi-static pressure-volume (P-V) curve, we analyzed 24 sets of inflation and deflation P-V curves obtained from patients with ARDS. We used a recently described sigmoidal equation to curve-fit the P-V data sets and objectively define the point of maximum compliance increase of the inflation limb (P mci,i) and the true inflection point of the deflation limb (P inf,d). These points were compared with graphic determinations of lower Pflex by seven clinicians. The graphic and curve-fitting methods were also compared for their ability to reproduce the same parameter value in data sets with reduced number of data points. The sigmoidal equation fit the P-V data with great accuracy (R 2 ϭ 0.9992). The average of Pflex determinations was found to be correlated with P mci,i (R ϭ 0.89) and P inf,d (R ϭ 0.76). Individual determinations of Pflex were less correlated with the corresponding objective parameters (R ϭ 0.67 and 0.62, respectively). Pflex ϩ 2 cm H 2 O was a more accurate estimator of P inf,d (2 SD ϭ Ϯ 6.05 cm H 2 O) than Pflex was of P mci,i (2 SD ϭ Ϯ 8.02 cm H 2 O). There was significant interobserver variability in Pflex, with a maximum difference of 11 cm H 2 O for the same patient (SD ϭ 1.9 cm H 2 O). Clinicians had difficulty reproducing Pflex in smaller data sets with differences as great as 17 cm H 2 O (SD ϭ 2.8 cm H 2 O). In contrast, the curve-fitting method reproduced P mci,i with great accuracy in reduced data sets (maximum difference of 1.5 cm H 2 O and SD ϭ 0.3 cm H 2 O). We conclude that Pflex rarely coincided with the point of maximum compliance increase defined by a sigmoid curve-fit with large differences in Pflex seen both among and within observers. Calculating objective parameters such as P mci,i or P inf,d from curve-fitted P-V data can minimize this large variability. Harris RS, Hess DR, Venegas JG. An objective analysis of the pressure-volume curve in the acute respiratory distress syndrome.
Pulmonary capillary pressures during the acute respiratory distress syndrome
Intensive Care Medicine, 2003
Objectives: (1)To describe the evolution of pulmonary capillary pressure (Pcap) and of the pressure drop across the pulmonary venous bed from early to established acute respiratory distress syndrome (ARDS), (2) to assess Pcap under different levels of positive end-expiratory pressure (PEEP) and (3) to compare the visual method and a mathematical model to determine Pcap. Design: Prospective, intervention study. Setting: Intensive care unit in a teaching institution. Patients: Nine ARDS patients, according to the ARDS Consensus Conference criteria. Interventions: Pulmonary arterial pressures were measured during routine respiratory mechanics measurements throughout ARDS. Four PEEP levels (6, 9, 12 and 15 cmH 2 O) were studied. Measurements and results: Pulmonary artery occlusions were made in triplicate at each PEEP level. Pcap was determined for every occlusion trace by three observers (visual method) and a mathematical model. Diastolic pulmonary artery pressure (PAPd) and pulmonary artery occlu-sion pressure (PAOP) were measured. The visually determined Pcap showed a bias of 2.5±2.1 mmHg as compared to the mathematical estimation. PAPd, Pcap and PAOP tended to decrease from early to late ARDS (p=0.128, 0.265, 0.121). Pcap−PAOP (6.3±2.7 mmHg) did not change throughout ARDS. Higher PEEP levels were associated with increased PAPd, Pcap and PAOP, as well as with larger Pcap−PAOP throughout ARDS. Conclusions: Pulmonary capillary pressure cannot be predicted from PAOP during early and established ARDS. The high variability in Pcap−PAOP increases the risk for underestimation of filtration pressures and consequently the risk for lung edema. Pcap can be estimated at the bedside by either the visual or mathematical methods.
2019
Background: Lung protective ventilation with low tidal volume is beneficial in patients with intermediate to high risk of postoperative pulmonary complications. However, during low tidal volume ventilation, pulse pressure variation (PPV) and stroke volume variation (SVV) do not predict fluid responsiveness. We aimed to determine whether changes in PPV and SVV after transient increases in tidal volume can predict fluid responsiveness in these patients. Methods: We recorded 22 measurements from 15 patients who experienced postoperative acute circulatory failure. We performed a tidal volume challenge by transiently increasing tidal volume (VT) from 6 to 8 mL/kg (VT6-8), 8 to 10 mL/kg (VT8-10), and 6 to 10 mL/kg (VT6-10) of patients' predicted body weight. The change in PPV (∆PPV) at VT6-8 (∆PPV6-8), VT8-10 (∆PPV8-10), VT6-10 (∆PPV6-10) and the change in SVV (∆SVV) at VT6-8 (∆SVV6-8), VT8-10 (∆SVV8-10), and VT6-10 (∆SVV6-10) were recorded. Patients were classified as fluid responders if there was an increase in stroke volume of more than 10% after a fluid bolus. Results: Following the tidal volume challenge, ∆PPV and ∆SVV failed to predict fluid responsiveness, with areas under the receiver operating characteristic curves (with 95% confidence intervals) of 0.
Critical care (London, England), 2017
Predicting fluid responsiveness may help to avoid unnecessary fluid administration during acute respiratory distress syndrome (ARDS). The aim of this study was to evaluate the diagnostic performance of the following methods to predict fluid responsiveness in ARDS patients under protective ventilation in the prone position: cardiac index variation during a Trendelenburg maneuver, cardiac index variation during an end-expiratory occlusion test, and both pulse pressure variation and change in pulse pressure variation from baseline during a tidal volume challenge by increasing tidal volume (VT) to 8 ml.kg. This study is a prospective single-center study, performed in a medical intensive care unit, on ARDS patients with acute circulatory failure in the prone position. Patients were studied at baseline, during a 1-min shift to the Trendelenburg position, during a 15-s end-expiratory occlusion, during a 1-min increase in VT to 8 ml.kg, and after fluid administration. Fluid responsiveness w...
Critical care (London, England), 2006
It is possible that taking a static pressure-volume (PV) measurement could durably affect oxygenation and thus interfere with early evaluation of a therapeutic intervention delivered just after that measurement. The aim of the present study was to investigate the effects over time of a single static PV measurement on gas exchange and haemodynamics; the PV measurements were taken using a super syringe and by using the constant flow method in patients with acute respiratory distress syndrome. We conducted a prospective, randomized and controlled interventional study in an intensive care unit. The study was conducted in 17 patients with early acute respiratory distress syndrome ventilated with a tidal volume of 6.9 +/- 1.0 ml/kg, a plateau pressure of 27 +/- 7 cmH2O and a positive end-expiratory pressure [PEEP] of 10 cmH2O. They were all evaluated for 1 hour after each of the following two measurements was taken and during a control period (in a randomized order): generation of a PV cu...
Critical Care, 2009
Introduction There is considerable uncertainty about the reproducibility of the various instruments used to measure dyspnea, their ability to reflect changes in symptoms, whether they accurately reflect the patient's experience and if its evolution is similar between acute heart failure syndrome patients and nonacute heart failure syndrome patients. URGENT was a prospective multicenter trial designed to address these issues. Methods Patients were interviewed within 1 hour of first physician evaluation, in the emergency department or acute care setting, with dyspnea assessed by the patient using both a five-point Likert scale and a 10-point visual analog scale (VAS) in the sitting (60º) and then supine (20º) position if dyspnea had not been considered severe or very severe by the sitting versus decubitus dyspnea measurement. Results Very good agreements were found between the five-point Likert and VAS at baseline (0.891, P <0.0001) and between changes (from baseline to hour 6) in the five-point Likert and in VAS (0.800, P <0.0001) in acute heart failure (AHF) patients. Lower agreements were found when changes from baseline to H6 measured by Likert or VAS were compared with the seven-point comparative Likert (0.512 and 0.500 respectively) in AHF patients. The worse the dyspnea at admission, the greater the amplitude of improvement in the first 6 hours; this relationship is stronger when dyspnea is measured with VAS (Spearman's rho coefficient = 0.672) than with the five-point Likert (0.272) (both P <0.0001) in AHF patients. By the five-point Likert, only nine patients (3% (1% to 5%)) reported an improvement in their dyspnea, 177 (51% (46% to 57%)) had no change, and 159 (46% (41% to 52%)) reported worse dyspnea supine compared with sitting up in AHF patients. The PDA test with VAS was markedly different between AHF and non-AHF patients. Conclusions Both clinical tools five-point Likert and VAS showed very good agreement at baseline and between changes from baseline to tests performed 6 hours later in AHF patients. The PDA test with VAS was markedly different between AHF and non-AHF patients. Dyspnea is improved within 6 hours in more than threequarters of the patients regardless of the tool used to measure the change in dyspnea. The greater the dyspnea at admission, the greater the amplitude of improvement in the first 6 hours.
American Journal of Respiratory and Critical Care Medicine, 1994
The effects of positive end-expiratory pressure (PEEP) on static ("rapid airway occlusion" technique) and dynamic ("constant flow" technique) volume-pressure (V-P) curves were studied in 19 patients with adult respiratory distress syndrome (ARDS). To describe the shape of both curves, the nonlinear coefficient of a second-order polynomial equation fitted to the static (static nonlinear coefficient) and dynamic (dynamic nonlinear coefficient) V-P curves on zero end-expiratory pressure (ZEEP) was used. Two distinct patterns were observed: (1) In ten patients, the static and dynamic V-P curves on ZEEP exhibited a convex shape with a progressive decrease in slope with increasing inflation VOlume (nonlinear coefficients: negative). In these patients PEEP induced a volume displacement along the static and dynamic V-P curves on ZEEP (hyperinflation). (2) In nine patients, the static and dynamic V-P curves on ZEEP showed a concave shape with a progressive increase in slope with increasing volume (nonlinear coefficients: positive) and PEEP shifted both curves upward along the volume axis (alveolar recruitment). A correlation (p < 0.0001) between static and dynamic nonlinear coefficients was found at all levels of PEEP. Both static and dynamic nonlinear coefficients on ZEEP were correlated (p < 0.0001) with the amount of lung volume recruited with PEEP, and the variations of cardiac index (CI), O 2 delivery (D0 2), right-to-Iett venous admixture (Os/Ot), and Pa0 2 with PEEP. Besides, the effects of PEEP on CI, Do 2 , Os/Ot, and Pa02 were less pronounced (p < 0.001) in patients with convex V-P curves than in patients with concave V-P curves. We conclude that analysis of the dynamic V-P curve ("constant flow" method) may replace the use of the static V-P curve ("occlusion technique") to assess the elastic properties of the respiratory system in ARDS patients. The dynamic V-P curve represents a simple and noninvasive clinical tool which detects hyperinflation and predicts the effects of PEEP on alveolar recruitment, hemodynamics, and gas exchange in ARDS patients.