A bedside index assessing the reliability of pulmonary artery occlusion pressure measurements during mechanical ventilation with positive end-expiratory pressure
TL;DR: The bedside determination of the ΔPpao/ΔPpa ratio should identify the cases in which Ppao measurements are not valid more reliably than lateral chest x-ray film, thus avoiding misleading interpretations of P pao during PEEP ventilation.
About: This article is published in Journal of Critical Care.The article was published on 1992-03-01. It has received 87 citations till now. The article focuses on the topics: Positive end-expiratory pressure & Pulmonary wedge pressure.
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TL;DR: As compared with conventional ventilation, the protective strategy was associated with improved survival at 28 days, a higher rate of weaning from mechanical ventilation, and a lower rate of barotrauma in patients with the acute respiratory distress syndrome.
Abstract: Background In patients with the acute respiratory distress syndrome, massive alveolar collapse and cyclic lung reopening and overdistention during mechanical ventilation may perpetuate alveolar injury. We determined whether a ventilatory strategy designed to minimize such lung injuries could reduce not only pulmonary complications but also mortality at 28 days in patients with the acute respiratory distress syndrome. Methods We randomly assigned 53 patients with early acute respiratory distress syndrome (including 28 described previously), all of whom were receiving identical hemodynamic and general support, to conventional or protective mechanical ventilation. Conventional ventilation was based on the strategy of maintaining the lowest positive end-expiratory pressure (PEEP) for acceptable oxygenation, with a tidal volume of 12 ml per kilogram of body weight and normal arterial carbon dioxide levels (35 to 38 mm Hg). Protective ventilation involved end-expiratory pressures above the lower inflection poin...
3,323 citations
TL;DR: It was concluded that in mechanically ventilated patients with acute circulatory failure related to sepsis, analysis of DeltaPp is a simple method for predicting and assessing the hemodynamic effects of VE, and that DeltaP p is a more reliable indicator of fluid responsiveness than DeltaPs.
Abstract: In mechanically ventilated patients with acute circulatory failure related to sepsis, we investigated whether the respiratory changes in arterial pressure could be related to the effects of volume expansion (VE) on cardiac index (CI). Forty patients instrumented with indwelling systemic and pulmonary artery catheters were studied before and after VE. Maximal and minimal values of pulse pressure (Pp(max) and Pp(min)) and systolic pressure (Ps(max) and Ps(min)) were determined over one respiratory cycle. The respiratory changes in pulse pressure (DeltaPp) were calculated as the difference between Pp(max) and Pp(min) divided by the mean of the two values and were expressed as a percentage. The respiratory changes in systolic pressure (DeltaPs) were calculated using a similar formula. The VE-induced increase in CI was >/= 15% in 16 patients (responders) and < 15% in 24 patients (nonresponders). Before VE, DeltaPp (24 +/- 9 versus 7 +/- 3%, p < 0.001) and DeltaPs (15 +/- 5 versus 6 +/- 3%, p < 0.001) were higher in responders than in nonresponders. Receiver operating characteristic (ROC) curves analysis showed that DeltaPp was a more accurate indicator of fluid responsiveness than DeltaPs. Before VE, a DeltaPp value of 13% allowed discrimination between responders and nonresponders with a sensitivity of 94% and a specificity of 96%. VE-induced changes in CI closely correlated with DeltaPp before volume expansion (r(2) = 0. 85, p < 0.001). VE decreased DeltaPp from 14 +/- 10 to 7 +/- 5% (p < 0.001) and VE-induced changes in DeltaPp correlated with VE-induced changes in CI (r(2) = 0.72, p < 0.001). It was concluded that in mechanically ventilated patients with acute circulatory failure related to sepsis, analysis of DeltaPp is a simple method for predicting and assessing the hemodynamic effects of VE, and that DeltaPp is a more reliable indicator of fluid responsiveness than DeltaPs.
1,178 citations
Cites background or methods from "A bedside index assessing the relia..."
...The correct position of the pulmonary artery catheter in West’s zone 3 was checked using a method previously described ( 16 )....
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...Second, by increasing pulmonary capillary pressure, VE may induce recruitment of pulmonary capillaries, leading to a decrease in West’s zone 2 ( 16 , 24) and hence a potential decrease in RV afterload during insufflation....
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TL;DR: It is demonstrated that cardiac filling pressures are poor predictors of fluid responsiveness in septic patients and their use as targets for volume resuscitation must be discouraged, at least after the early phase of sepsis has concluded.
Abstract: Objective:Values of central venous pressure of 8–12 mm Hg and of pulmonary artery occlusion pressure of 12–15 mm Hg have been proposed as volume resuscitation targets in recent international guidelines on management of severe sepsis. By analyzing a large number of volume challenges, our aim was to t
609 citations
Cites methods from "A bedside index assessing the relia..."
...The correct position of the pulmonary artery catheter in West’s zone 3 was checked using a method previously described (6)....
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TL;DR: Analysis of respiratory changes in aortic blood velocity is an accurate method for predicting the hemodynamic effects of volume expansion in septic shock patients receiving mechanical ventilation who have preserved left ventricular systolic function.
547 citations
TL;DR: The dDown component of the systolic pressure variation is a sensitive indicator of the response of cardiac output to volume infusion in patient with sepsis‐induced hypotension who require mechanical ventilation.
Abstract: BackgroundMonitoring left ventricular preload is critical to achieve adequate fluid resuscitation in patients with hypotension and sepsis. This prospective study tested the correlation of the pulmonary artery occlusion pressure, the left ventricular end-diastolic area index measured by transesophage
523 citations
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TL;DR: The left lung from a dog was removed, ventilated with negative pressure, and perfused with venous blood to establish pulmonary arterial, venous, and alveolar pressures that could be varied over a large range.
Abstract: The left lung from a dog was removed, ventilated with negative pressure, and perfused with venous blood. Pulmonary arterial, venous, and alveolar pressures could be varied over a large range. The d...
1,007 citations
TL;DR: It is concluded that decreased cardiac output during PEEP is mediated by a leftward displacement of the interventricular septum, which restricts left ventricular filling.
Abstract: Although left ventricular dysfunction is common during ventilatory support with positive end-expiratory pressure (PEEP), the mechanism of this disorder remains unclear. In 10 patients with the adult respiratory-distress syndrome we studied the effects of a stepwise increase in PEEP from 0.to 30 cm H2O on left ventricular output, intracardiac transmural pressures, and two-dimensional echocardiographic measurements of left ventricular cross-sectional area at end-systole and at end-diastole. Increasing PEEP was associated with progressive declines in cardiac output, mean blood pressure, and left ventricular dimensions and with equalization of right and left ventricular filling pressures. The radius of septal curvature decreased at both end-diastole and end-systole, implying a leftward shift of the interventricular septum. At the highest PEEP, blood-volume expansion did not restore cardiac output, although left ventricular transmural filling pressures had returned to base-line values. We conclude that decreased cardiac output during PEEP is mediated by a leftward displacement of the interventricular septum, which restricts left ventricular filling.
603 citations
TL;DR: This review focuses on the clinical physiologic aspects of the wedge pressure determination, the technical principles of measurement, and the practical application of the information Pw provides.
Abstract: Bedside measurement of the pulmonary artery occlusion pressure (wedge, Pw) has become routine in the practice of critical care. Although Pw is a potentially useful index of left ventricular filling pressure and pulmonary vascular congestion, an invalid or misinterpreted value can prompt inappropriate clinical decisions. To avoid error Pw must be measured precisely and interpreted carefully, with consideration given to disordered cardiopulmonary mechanics and to the objectives of therapy. This review focuses on the clinical physiologic aspects of the wedge pressure determination, the technical principles of measurement, and the practical application of the information Pw provides.
154 citations
TL;DR: Methods of estimating LV filling pressure using Ppao measurements under conditions in which increases in Ppc were the primary determinants of differences in the two measurements were examined.
Abstract: In the critically ill, accurate measurements of left ventricular (LV) filling pressure using pulmonary artery occlusion pressure (Ppao) are important for diagnostic and therapeutic purposes. In patients receiving positive end-expiratory pressure (PEEP), Ppao may not reflect LV filling pressure because of elevated pericardial pressure (Ppc). It has been proposed that in humans, Ppc and right atrial pressure (PRA) are equal, so that referencing Ppao to PRA may improve the assessment of LV filling pressure when Ppc is elevated. Similarly, it has also been shown in the dog that nadir Ppao immediately after airway disconnection from PEEP (nadir Ppao), accurately reflects LV filling pressure when LV filling pressure is greater than or equal to 10 mm Hg. We examined methods of estimating LV filling pressure using Ppao measurements under conditions in which increases in Ppc were the primary determinants of differences in the two measurements. Using left atrial pressure (PLA) relative to Ppc, called transmural PLA (PLAtm), as LV filling pressure, we compared the accuracy of Ppao, nadir Ppao, and Ppao relative to PRA to reflect PLAtm in 15 postoperative cardiac surgery patients in whom an air-filled pericardial balloon catheter and a left atrial catheter were inserted during surgery. PEEP was sequentially increased from zero to 15 cm H2O. We found that PRA always exceeded Ppc (p less than 0.01) and increased less with PEEP than did Ppc (p less than 0.05). At less than or equal to 5 cm H2O PEEP, both Ppao and nadir Ppao were similar to each other and to PLAtm.(ABSTRACT TRUNCATED AT 250 WORDS)
123 citations
TL;DR: Measurements of net left atrial pressure and stroke work indicated that high levels of PEEP resulted in left ventricular failure, which may have been due to reduced coronary flow secondary to an elevated myocardial interstitial pressure with high level PEEP.
Abstract: A prospective study of five patients was performed utilizing both left atrial and wedge catheters. As positive end expiratory pressure (PEEP) was altered, left atrial pressure, cardiac index, net left atrial pressure, pulmonary vascular resistance, and stroke work were determined. At low levels of PEEP, wedge and left atrial pressure correlated significantly ( r =.83). As PEEP increased, cardiac index was frequently compromised. Measurements of net left atrial pressure and stroke work indicated that high levels of PEEP resulted in left ventricular failure. This may have been due to reduced coronary flow secondary to an elevated myocardial interstitial pressure with high levels of PEEP.
109 citations