<title>Effect of acute lung injury on the spatial correlation of regional pulmonary blood flow</title>

Background Sustained lung inflations (recruitment maneuvers [RMs]) are occasionally used during mechanical ventilation of patients with acute lung injury to restore aeration to atelectatic alveoli. However, RMs do not improve, and may even worsen, gas exchange in a fraction of these patients. In this study, the authors sought to determine the mechanism by which an RM can impair gas exchange in acute lung injury. Methods The authors selected a model of acute lung injury that was unlikely to exhibit sustained recruitment in response to a lung inflation. In five sheep, lung injury was induced by lavage with 0.2% polysorbate 80 in saline. Positron emission tomography and [13N]nitrogen were used to assess regional lung function in dependent, middle, and nondependent lung regions. Physiologic data and positron emission scans were collected before and 5 min after a sustained inflation (continuous positive airway pressure of 50 cm H2O for 30 s). Results All animals showed greater loss of aeration and higher perfusion and shunting blood flow in the dependent region. After the RM, Pao2 decreased in all animals by 35 +/- 22 mmHg (P < 0.05). This decrease in Pao2 was associated with redistribution of pulmonary blood flow from the middle, more aerated region to the dependent, less aerated region (P < 0.05) and with an increase in the fraction of pulmonary blood flow that was shunted in the dependent region (P < 0.05). Neither respiratory compliance nor aeration of the dependent region improved after the RM. Conclusions When a sustained inflation does not restore aeration to atelectatic regions, it can worsen oxygenation by increasing the fraction of pulmonary blood flow that is shunted in nonaerated regions.

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Changes in Pulmonary Blood Flow during Gaseous and Partial Liquid Ventilation in Experimental Acute Lung Injury

Anesthesiology ◽

10.1097/00000542-200012000-00016 ◽

2000 ◽

Vol 93 (6) ◽

pp. 1437-1445 ◽

Cited By ~ 6

Author(s):

Martin Max ◽

Bernd Nowak ◽

Rolf Dembinski ◽

Gernot Schulz ◽

Ralf Kuhlen ◽

...

Keyword(s):

Blood Flow ◽

Acute Lung Injury ◽

Lung Injury ◽

Pulmonary Blood Flow ◽

Arterial Oxygen ◽

Pulmonary Vasculature ◽

Emission Computed Tomography ◽

Partial Liquid Ventilation ◽

Arterial Oxygenation ◽

Liquid Ventilation

Background It has been proposed that partial liquid ventilation (PLV) causes a compression of the pulmonary vasculature by the dense perfluorocarbons and a subsequent redistribution of pulmonary blood flow from dorsal to better-ventilated middle and ventral lung regions, thereby improving arterial oxygenation in situations of acute lung injury. Methods After induction of acute lung injury by repeated lung lavage with saline, 20 pigs were randomly assigned to partial liquid ventilation with two sequential doses of 15 ml/kg perfluorocarbon (PLV group, n = 10) or to continued gaseous ventilation (GV group, n = 10). Single-photon emission computed tomography was used to study regional pulmonary blood flow. Gas exchange, hemodynamics, and pulmonary blood flow were determined in both groups before and after the induction of acute lung injury and at corresponding time points 1 and 2 h after each instillation of perfluorocarbon in the PLV group. Results During partial liquid ventilation, there were no changes in pulmonary blood flow distribution when compared with values obtained after induction of acute lung injury in the PLV group or to the animals submitted to gaseous ventilation. Arterial oxygenation improved significantly in the PLV group after instillation of the second dose of perfluorocarbon. Conclusions In the surfactant washout animal model of acute lung injury, redistribution of pulmonary blood flow does not seem to be a major factor for the observed increase of arterial oxygen tension during partial liquid ventilation.

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A Method To Measure Regional Pulmonary Blood Flow with Transesophageal Echocardiography in Acute Lung Injury Dog Model

Anesthesiology ◽

10.1097/00000542-200209002-01351 ◽

2002 ◽

Vol 96 (Sup 2) ◽

pp. A1351

Author(s):

Toshihito Tsubo ◽

Yuichi Yatsu ◽

Eiji Hashiba ◽

Hironori Ishihara ◽

Akitomo Matsuki

Keyword(s):

Blood Flow ◽

Acute Lung Injury ◽

Lung Injury ◽

Transesophageal Echocardiography ◽

Pulmonary Blood Flow ◽

Dog Model

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Pulmonary blood flow and flow-dependent metabolic function during acute lung injury

Critical Care Medicine ◽

10.1097/00003246-199901000-00014 ◽

1999 ◽

Vol 27 (1) ◽

pp. 21-22

Author(s):

George M. Matuschak ◽

Paul B. Zanaboni

Keyword(s):

Blood Flow ◽

Acute Lung Injury ◽

Lung Injury ◽

Pulmonary Blood Flow ◽

Metabolic Function

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Pulmonary blood flow distribution during gaseous and partial liquid ventilation (PLV) in experimental acute lung injury (ALI)

European Journal of Anaesthesiology ◽

10.1097/00003643-200000002-00556 ◽

2000 ◽

Vol 17 (Supplement 19) ◽

pp. 170

Author(s):

M. Max ◽

B. Nowak ◽

R. Dembinski ◽

R. Kuhlen ◽

R. Rossaint

Keyword(s):

Blood Flow ◽

Acute Lung Injury ◽

Lung Injury ◽

Pulmonary Blood Flow ◽

Flow Distribution ◽

Partial Liquid Ventilation ◽

Blood Flow Distribution ◽

Liquid Ventilation

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Redistribution of Pulmonary Blood Flow Impacts Thermodilution-based Extravascular Lung Water Measurements in a Model of Acute Lung Injury

Anesthesiology ◽

10.1097/aln.0b013e3181bc99cf ◽

2009 ◽

Vol 111 (5) ◽

pp. 1065-1074 ◽

Cited By ~ 30

Author(s):

R Blaine Easley ◽

Daniel G. Mulreany ◽

Christopher T. Lancaster ◽

Jason W. Custer ◽

Ana Fernandez-Bustamante ◽

...

Keyword(s):

Blood Flow ◽

Acute Lung Injury ◽

Lung Injury ◽

Pulmonary Blood Flow ◽

Hypoxic Pulmonary Vasoconstriction ◽

Shunt Fraction ◽

Lung Water ◽

Computed Tomographic ◽

Pulmonary Vasoconstriction

Background Studies using transthoracic thermodilution have demonstrated increased extravascular lung water (EVLW) measurements attributed to progression of edema and flooding during sepsis and acute lung injury. The authors hypothesized that redistribution of pulmonary blood flow can cause increased apparent EVLW secondary to increased perfusion of thermally silent tissue, not increased lung edema. Methods Anesthetized, mechanically ventilated canines were instrumented with PiCCO (Pulsion Medical, Munich, Germany) catheters and underwent lung injury by repetitive saline lavage. Hemodynamic and respiratory physiologic data were recorded. After stabilized lung injury, endotoxin was administered to inactivate hypoxic pulmonary vasoconstriction. Computed tomographic imaging was performed to quantify in vivo lung volume, total tissue (fluid) and air content, and regional distribution of blood flow. Results Lavage injury caused an increase in airway pressures and decreased arterial oxygen content with minimal hemodynamic effects. EVLW and shunt fraction increased after injury and then markedly after endotoxin administration. Computed tomographic measurements quantified an endotoxin-induced increase in pulmonary blood flow to poorly aerated regions with no change in total lung tissue volume. Conclusions The abrupt increase in EVLW and shunt fraction after endotoxin administration is consistent with inactivation of hypoxic pulmonary vasoconstriction and increased perfusion to already flooded lung regions that were previously thermally silent. Computed tomographic studies further demonstrate in vivo alterations in regional blood flow (but not lung water) and account for these alterations in shunt fraction and EVLW.

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