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Now showing items 17 - 31 of 31

  • Alveolar recruitment assessed by positron emission tomography during experimental acute lung injury RID A-4097-2009

    Richard, Jean-Christophe   Le Bars, Didier   Costes, Nicolas   Bregeon, Fabienne   Tourvieille, Christian   Lavenne, Franck   Janier, Marc   Gimenez, Gerard   Guerin, Claude  

    Objectives: To compare changes in aerated lung volumes measured by positron emission tomography (PET) and inflation volume-pressure curve (V-P) of the respiratory system, and to evaluate the reliability of PET to assess alveolar recruitment. Design and settings: Experimental study in six anesthetized and mechanically ventilated pigs in a PET facility in an experimental university laboratory. Interventions: Lung injury was induced by oleic acid. Animals were randomly studied in four conditions: PEEP 0 cmH(2)O (ZEEP) in supine position (SP), PEEP 10 cmH(2)O in SP, ZEEP in prone position (PP) and PEEP in PP, each applied for 30 min. Measurements and results: With PET aerated lung volume was obtained from pulmonary density analysis using transmission scan (VA(trans)) and from nitrogen-13 kinetics on emission scan (VA(em)). Changes in VA(trans) and VA(em) were computed as the difference in aerated volume between conditions. VA(trans) and VA(em) did not differ between SP and PP, on either ZEEP or PEEP, suggesting no modification in relaxation volume of the respiratory system induced by posture. Changes in VA(trans) or VA(em) were significantly correlated with changes in aerated volume assessed from superimposed V-P curves (R(2) = 0.74 and 0.75, respectively). Alveolar recruitment assessed by PET was significantly correlated with both PaO(2) (R(2) = 0.61) and PaCO(2) (R(2) = 0.40) variations induced by PEEP. Conclusions: PET is a new reliable tool of scientific interest to image lung volume and alveolar recruitment during acute lung injury.
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  • Preparation of an intensive care unit in France for the reception of a confirmed case of Ebola virus infection

    Dubost, Clement   Pasquier, Pierre   Kearns, Kevin   Ficko, Cecile   Rapp, Christophe   Wolff, Michel   Richard, Jean-Christophe   Diehl, Jean-Luc   Le Tulzo, Yves   Merat, Stephane  

    The current Ebola Virus Disease (EVD) outbreak in West Africa is a major challenge for the worldwide medical community. On April 29th 2015, the World Health Organization (WHO) declared 26,277 infected cases; among them, 10,884 have deceased. The epidemic is still ongoing, particularly in Sierra Leone. It is now clear that northern countries will be implicated in the care of EVD patients, both in the field and back at home. Because of the severity of EVD, a fair amount of patients may require intensive care. It is highly probable that intensive care would be able to significantly reduce the mortality linked with EVD. The preparation of a modern Intensive Care Unit (ICU) to treat an EVD patient in good conditions requires time and specific equipment. The cornerstone of this preparation includes two main goals: treating the patient and protecting healthcare providers. Staff training is time consuming and must be performed far in advance of patient arrival. To be efficient, preparation should be planned at a national level with help from public authorities, as was the case in France during the summer of 2014. Due to the severity of the disease, the high risk of transmission and scarce knowledge on EVD treatment, our propositions are necessarily original and innovative. Our review includes four topics: a brief report on the actual outbreak, where to receive and hospitalize the patients, the specific organization of the ICU and finally ethical aspects. (C) 2015 Societe francaise d'anesthesie et de reanimation (Sfar). Published by Elsevier Masson SAS. All rights reserved.
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  • Respective effects of end-expiratory and end-inspiratory pressures on alveolar recruitment in acute lung injury.

    Richard, Jean-Christophe   Brochard, Laurent   Vandelet, Philippe   Breton, Lucie   Maggiore, Salvatore M   Jonson, Bjorn   Clabault, Karine   Leroy, Jacques   Bonmarchand, Guy  

    OBJECTIVE: A low tidal volume can induce alveolar derecruitment in patients with acute lung injury. This study was undertaken to evaluate whether this resulted mainly from the decrease in tidal volume or from the reduction in end-inspiratory plateau pressure and whether there is any benefit in raising the level of positive end-expiratory pressure (PEEP) while plateau pressure is kept constant.DESIGN: Prospective crossover study.SETTING: Medical intensive care unit of a university teaching hospital.PATIENTS: Fifteen adult patients ventilated for acute lung injury (PaO2/FiO2, 158 +/- 34 mm Hg; lung injury score, 2.7 +/- 0.6).INTERVENTIONS: Three combinations were tested: PEEP at the lower inflection point with 6 mL/kg tidal volume, PEEP at the lower inflection point with 10 mL/kg tidal volume, and high PEEP with tidal volume at 6 mL/kg, keeping the plateau pressure similar to the preceding condition.MEASUREMENTS AND MAIN RESULTS: Pressure-volume curves at zero PEEP and at set PEEP were recorded, and recruitment was calculated as the volume difference between both curves for pressures ranging from 15 to 30 cm H2O. Arterial blood gases were measured for all patients. For a similar PEEP at the lower inflection point (10 +/- 3 cm H2O), tidal volume reduction (10 to 6 mL/kg) led to a significant derecruitment. A low tidal volume (6 mL/kg) with high PEEP (14 +/- 3 cm H2O), however, induced a significantly greater recruitment and a higher Pao than the two other strategies.CONCLUSION: At a given plateau pressure (i.e., similar end-inspiratory distension), lowering tidal volume and increasing PEEP increase recruitment and PaO2.
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  • Respective effects of end-expiratory and end-inspiratory pressures on alveolar recruitment in acute lung injury*

    Richard, Jean-Christophe   Brochard, Laurent   Vandelet, Philippe   Breton, Lucie   Maggiore, Salvatore M.   Jonson, Bjorn   Clabault, Karine   Leroy, Jacques   Bonmarchand, Guy  

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  • Effect of activated protein C on pulmonary blood flow and cytokine production in experimental acute lung injury RID A-4097-2009

    Richard, Jean-Christophe   Bregeon, Fabienne   Leray, Veronique   Le Bars, Didier   Costes, Nicolas   Tourvieille, Christian   Lavenne, Franck   Devouassoux-Shisheboran, Mojgan   Gimenez, Gerard   Guerin, Claude  

    Objective: In acute lung injury (ALI) activated protein C (APC) may reopen occluded lung vessels and minimize lung inflammation. We aimed at assessing the effect of APC on regional lung perfusion, aerated lung volume, cytokine production and oxygenation in experimental ALI. Design and setting: Prospective, controlled study in an imaging facility. Participants: Pigs tracheotomized and mechanically ventilated. Intervention: Pigs were randomly given intravenously APC (n= 8) or saline (n = 8). Thirty minutes later, ALI was induced by injecting oleic acid. Measurements and results: Lung perfusion and aerated lung volume measured with positron emission tomography, plasma cytokines and arterial blood gas were determined just before ALI and 110 and 290 min thereafter. Lung cytokines were measured at the end of the experiment. PaO2 under FIO2 1 was significantly lower in the APC group before lung injury (473 +/- 129 vs. 578 +/- 54 mmHg) and 110 min (342 +/- 138 vs. 446 +/- 103 mmHg) and 290 min (303 +/- 171 vs. 547 +/- 54 mmHg) thereafter (p < 0.05). Lung perfusion nonsignificantly tended to redistribute towards dorsal lung regions with APC. Total aerated lung volume was not different between APC and control before ALI (10.0 +/- 1.5 vs. 11.0 +/- 2.5 ml/kg) (p > 0.05) or thereafter. Plasma IL-6 and IL-8 at 110 min were greater with APC (p < 0.05). Conclusions: In contrast to studies using other models, pretreatment with APC was associated with worsening oxygenation in the present investigation. This might be due to ventilation-perfusion mismatch, with more perfusion to dependent nonaerated areas.
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  • Voxel-wise assessment of lung aeration changes on CT images using image registration: application to acute respiratory distress syndrome (ARDS)

    Orkisz, Maciej   Morales Pinzón, Alfredo   Richard, Jean-Christophe   Guérin, Claude   Solórzano Vargas, Leslie Evelyn   Sicaru, Daniela Florentina   García Hernández, Camila   Gómez Ballén, Margarita M.   Neyran, Bruno   Dávila Serrano, Eduardo E.   Hernández Hoyos, Marcela  

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  • Performance of the Cough Assist Insufflation-Exsufflation Device in the Presence of an Endotracheal Tube or Tracheostomy Tube: A Bench Study

    Guerin, Claude   Bourdin, Gael   Leray, Veronique   Delannoy, Bertrand   Bayle, Frederique   Germain, Michele   Richard, Jean-Christophe  

    BACKGROUND: The Cough Assist is a mechanical insufflator-exsufflator designed to assist airway secretion clearance in patients with ineffective cough. The device may benefit intubated and tracheotomized patients. We assessed the impact of various artificial airways on peak expiratory flow (PEF) with the Cough Assist. METHODS: We measured PEF and pressure at the airway opening in a lung model during insufflation-exsufflation with the Cough Assist, at 3 set pressures: 30/-30, 401-40, and 50/-50 cm H(2)O, first without (control), and then with different sizes (6.5 to 8.5 mm inner diameter) of endotracheal tube (ETT) and tracheostomy tube (6, 7, and 8 mm inner diameter), compliance settings of 30 and 60 mL/cm H(2)O, and resistance settings of 0 and 5 cm H(2)O/L/s). We analyzed the relationship between PEF and pressure with linear regression. RESULTS: With compliance of 30 mL/cm H(2)O and 0 resistance the slope of the control relationship between PEF and pressure was statistically significantly greater than during any conditions with ETT or tracheostomy tube. Therefore, in comparison to the control, the relationship of PEF to pressure significantly went in the direction from top to bottom as the ETT or tracheostomy tube became narrower. The findings were the same with compliance of 30 mL/cm H(2)O and resistance of 5 cm H(2)O/L/s. With compliance of 60 mL/cm H(2)O the highest set pressure values were not achieved and some relationships departed from linearity. The control slope of the relationship between PEF and pressure with compliance of 60 mL/cm H(2)O and 0 resistance did not significantly differ with any ETT or tracheostomy tube. CONCLUSIONS. The artificial airways significantly reduced PEF during insufflation-exsufflation with Cough Assist; the narrower the inner diameter of the artificial airway, the lower the PEF for a given expiratory pressure.
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  • The impact of patient positioning on pressure ulcers in patients with severe ARDS: results from a multicentre randomised controlled trial on prone positioning.

    Girard, Raphaele   Baboi, Loredana   Ayzac, Louis   Richard, Jean-Christophe   Guerin, Claude  

    PURPOSE: Placing patients with severe acute respiratory distress syndrome (ARDS) in the prone position has been shown to improve survival as compared to the supine position. However, a higher frequency of pressure ulcers has been reported in patients in the prone position. The objective of this study was to verify the impact of prone positioning on pressure ulcers in patients with severe ARDS.; METHODS: This was an ancillary study of a prospective multicentre randomised controlled trial in patients with severe ARDS in which the early application of long prone-positioning sessions was compared to supine positioning in terms of mortality. Pressure ulcers were assessed at the time of randomisation, 7 days later and on discharge from the intensive care unit (ICU), using the four-stage Pressure Ulcers Advisory Panel system. The primary end-point was the incidence (with reference to 1,000 days of invasive mechanical ventilation or 1,000 days of ICU stay) of new patients with pressure ulcers at stage 2 or higher from randomisation to ICU discharge.; RESULTS: At randomisation, of the 229 patients allocated to the supine position and the 237 patients allocated to the prone position, the number of patients with pressure ulcers was not significantly different between groups. The incidence of new patients with pressure ulcers from randomisation to ICU discharge was 20.80 and 14.26/1,000 days of invasive mechanical ventilation (P =3D 0.061) and 13.92 and 7.72/1,000 of ICU days (P =3D 0.002) in the prone and supine groups, respectively. Position group [odds ratio (OR) 1.5408, P =3D 0.0653], age >60 years (OR 1.5340, P =3D 0.0019), female gender (OR 0.5075, P =3D 0.019), body mass index of >28.4 kg/m(2) (OR 1.9804, P =3D 0.0037), and a Simplified Acute Physiology Score II at inclusion of >46 (OR 1.2765, P =3D 0.3158) were the covariates independently associated to the acquisition of pressure ulcers.; CONCLUSION: In patients with severe ARDS, prone positioning was associated with a higher frequency of pressure ulcers than the supine position. Prone positioning improves survival in patients with severe ARDS and, therefore, survivors who received this intervention had a greater likelihood of having pressure ulcers documented as part of their follow-up. There are risk groups for the development of pressure ulcers in severe ARDS, and these patients need surveillance and active prevention.=20
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  • Management and Long-Term Outcome of Patients With Chronic Neuromuscular Disease Admitted to the Intensive Care Unit for Acute Respiratory Failure: A Single-Center Retrospective Study

    Flandreau, Ghislain   Bourdin, Gael   Leray, Veronique   Bayle, Frederique   Wallet, Florent   Delannoy, Bertrand   Durante, Gerard   Vincent, Bernard   Barbier, Jack   Burle, Jean-Francois   Passant, Sandrine   Richard, Jean-Christophe   Guerin, Claude  

    BACKGROUND: Patients with chronic neuromuscular disease represent less than 10% of those receiving mechanical ventilation in the intensive care unit (ICU). Little has been reported regarding either ICU management of acute respiratory failure (ARF) in the era of noninvasive mechanical ventilation (NIV) or long-term outcomes. OBJECTIVE: To describe the respiratory management of patients with chronic neuromuscular diseases admitted to our university hospital ICU for ARF, and the long-term outcomes. METHODS: We retrospectively analyzed patients with chronic neuromuscular diseases admitted to our ICU for a first episode of ARF between January 1, 1996, and February 27, 2007. We assessed severity of illness on ICU admission, respiratory management during ICU stay, and outcomes on June 15, 2008. RESULTS: During the study period, 87 patients (44 with hereditary and 43 with acquired neuromuscular diseases) had their first ARF episode that required ICU admission. In the hereditary-diseases group and the acquired-diseases group, respectively, the rates of NIV use during the ICU stay were 82% and 63% (P = .040), the intubation rates were 30% and 56% (P = .02), and the tracheotomy rates were 9% and 12% (difference not significant). At the final assessment (median 3 years) the mortality rate was 58%, and mortality was not significantly related to the type of neuromuscular disease. At final assessment, 46% of the patients were on NIV and 29% had tracheotomy. CONCLUSIONS: In our ICU, chronic neuromuscular disease is an uncommon cause of ARF, for which we often use NIV. These patients had a low probability of death in the ICU. Long-term outcome was independent of the type of neuromuscular disease.
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  • Expiratory flow-volume loop profile and patient outcome in chronic obstructive pulmonary disease in acute respiratory failure: a prospective observational study in a single intensive care unit.

    Porot, Veronique   Ernesto, Sylvie   Leray, Veronique   Delannoy, Bertrand   Bourdin, Gael   Bayle, Frederique   Richard, Jean-Christophe   Guerin, Claude  

    BACKGROUND: Expiratory flow-volume (EFV) loops are continuously displayed on the screen of intensive care unit (ICU) ventilators.; OBJECTIVES: It was the aim of this study to investigate the relationships of EFV to chronic obstructive pulmonary disease (COPD) patient outcome.; METHODS: This is a prospective study on COPD patients who received invasive mechanical ventilation for acute respiratory failure in the ICU. Within the 24-hour post-intubation period, the angle of the EFV slope during the last 50% of expiration was computed and patients were stratified into 4 quartiles. Resistance, compliance of the respiratory system and change in end-expiratory lung volume above relaxation volume were assessed. Patients were followed up to hospital discharge. The main outcome was hospital mortality. Secondary outcomes were ICU mortality, length of ICU stay, duration of invasive ventilation, number of intubations, oxygen and non-invasive ventilation.; RESULTS: Thirty-eight patients were analysed. The first quartile comprised 9 patients (median angle 11=C2=B0, interquartile range 8-12), the second 10 patients (median angle 26=C2=B0, range 19-30), the third 10 patients (median angle 42=C2=B0, range 39-46), and the fourth 9 patients (median angle 53=C2=B0, range 49-64). Hospital and ICU mortality were not different between groups. Lengths of ICU and hospital stay and length of invasive ventilation were significantly different between groups, with the highest values observed in the first quartile. The rate of oxygen use and non-invasive ventilation in the ICU and at hospital discharge was significantly different between groups, with the highest rate observed in the first quartile. There was a significant negative correlation between angle and resistance, compliance of the respiratory system and change in end-expiratory lung volume above the relaxation volume.; CONCLUSION: The slope of the angle during the last 50% of expired volume in the COPD patients was associated with worsened respiratory mechanics and higher morbidity. Copyright =C2=A9 2011 S. Karger AG, Basel.
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  • Change in cardiac output during Trendelenburg maneuver is a reliable predictor of fluid responsiveness in patients with acute respiratory distress syndrome in the prone position under protective ventilation

    Yonis, Hodane   Bitker, Laurent   Aublanc, Mylene   Ragey, Sophie Perinel   Riad, Zakaria   Lissonde, Floriane   Louf-Durier, Aurore   Debord, Sophie   Gobert, Florent   Tapponnier, Romain   Guerin, Claude   Richard, Jean-Christophe  

    Background: 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(-1). Methods: 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(-1), and after fluid administration. Fluid responsiveness was deemed present if cardiac index assessed by transpulmonary thermodilution increased by at least 15% after fluid administration. Results: There were 33 patients included, among whom 14 (42%) exhibited cardiac arrhythmia at baseline and 15 (45%) were deemed fluid-responsive. The area under the receiver operating characteristic (ROC) curve of the pulse contourderived cardiac index change during the Trendelenburg maneuver and the end-expiratory occlusion test were 0.90 (95% CI, 0.80-1.00) and 0.65 (95% CI, 0.46-0.84), respectively. An increase in cardiac index >=3D 8% during the Trendelenburg maneuver enabled diagnosis of fluid responsiveness with sensitivity of 87% (95% CI, 67-100), and specificity of 89% (95% CI, 72-100). The area under the ROC curve of pulse pressure variation and change in pulse pressure variation during the tidal volume challenge were 0.52 (95% CI, 0.24-0.80) and 0.59 (95% CI, 0.31-0.88), respectively. Conclusions: Change in cardiac index during a Trendelenburg maneuver is a reliable test to predict fluid responsiveness in ARDS patients in the prone position, while neither change in cardiac index during end-expiratory occlusion, nor pulse pressure variation during a VT challenge reached acceptable predictive performance to predict fluid responsiveness in this setting.
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  • Management of neutropenic patients in the intensive care unit (NEWBORNS EXCLUDED) recommendations from an expert panel from the French Intensive Care Society (SRLF) with the French Group for Pediatric Intensive Care Emergencies (GFRUP), the French Society of Anesthesia and Intensive Care (SFAR), the French Society of Hematology (SFH), the French Society for Hospital Hygiene (SF2H), and the French Infectious Diseases Society (SPILF).

    Schnell, David   Azoulay, Elie   Benoit, Dominique   Clouzeau, Benjamin   Demaret, Pierre   Ducassou, Stephane   Frange, Pierre   Lafaurie, Matthieu   Legrand, Matthieu   Meert, Anne-Pascale   Mokart, Djamel   Naudin, Jerome   Pene, Frederic   Rabbat, Antoine   Raffoux, Emmanuel   Ribaud, Patricia   Richard, Jean-Christophe   Vincent, Francois   Zahar, Jean-Ralph   Darmon, Michael  

    Neutropenia is defined by either an absolute or functional defect (acute myeloid leukemia or myelodysplastic syndrome) of polymorphonuclear neutrophils and is associated with high risk of specific complications that may require intensive care unit (ICU) admission. Specificities in the management of critically ill neutropenic patients prompted the establishment of guidelines dedicated to intensivists. These recommendations were drawn up by a panel of experts brought together by the French Intensive Care Society in collaboration with the French Group for Pediatric Intensive Care Emergencies, the French Society of Anesthesia and Intensive Care, the French Society of Hematology, the French Society for Hospital Hygiene, and the French Infectious Diseases Society. Literature review and formulation of recommendations were performed using the Grading of Recommendations Assessment, Development and Evaluation system. Each recommendation was then evaluated and rated by each expert using a methodology derived from the RAND/UCLA Appropriateness Method. Six fields are covered by the provided recommendations: (1) ICU admission and prognosis, (2) protective isolation and prophylaxis, (3) management of acute respiratory failure, (4) organ failure and organ support, (5) antibiotic management and source control, and (6) hematological management. Most of the provided recommendations are obtained from low levels of evidence, however, suggesting a need for additional studies. Seven recommendations were, however, associated with high level of evidences and are related to protective isolation, diagnostic workup of acute respiratory failure, medical management, and timing surgery in patients with typhlitis. =20
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  • Inhaled bronchodilator administration during mechanical ventilation: How to optimize it, and for which clinical benefit? RID A-4097-2009

    Guerin, Claude   Fassier, Thomas   Bayle, Frederique   Lemasson, Stephane   Richard, Jean-Christophe  

    Bronchodilators are frequently used in ICU patients, and are the most common medications administered by inhalation during mechanical ventilation. The amount of bronchodilator that deposits at its site of action depends on the amount of drug, inhaled mass, deposited mass, and particle size distribution. Mechanical ventilation challenges both inhaled mass'and lung deposition by specific features, such as a ventilatory circuit, an endotracheal tube, and ventilator settings. Comprehensive in vitro studies have shown that an endotracheal tube is not as significant a barrier for the drug to travel as anticipated. Key variables o ' f drug deposition are attachments of the inhalation device in the inspiratory line 10 to 30 cm to the'endotracheal tube, use of chamber with metered-dose inhaler, dry air, high tidal volume, low respiratory frequency,.and low inspiratory flow, which can increase the drug deposition. In vivo studies showed that a reduction by roughly 15% of the respiratory resistance was achieved with inhaled bronchodilators during invasive mechanical ventilation. The role of ventilatory settings is not as clear in vivo, and primary factors for optimal delivery and physiologic effects were medication dose and device location. Nebulizers and pressurized metered-dose inhalers can equally achieve physiologic end points. The effects of bronchodilators should be carefully evaluated, which can easily be done with the interrupter technique. With the noninvasive ventilation, the data regarding drug delivery and physiologic effects are still limited. With the bilevel ventilators the inhalation device should be located between the leak port and face mask. Further studies should investigate the effects of inhaled bronchodilators on patient outcome and methods to optimize delivery of inhaled bronchodilators during noninvasive ventilation.
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  • Polarization dependent formalism of interferometric structures describing DPSK and DQPSK receivers

    Chen, Lawrence R.   Samadi, Payman   Richard, Jean-Christophe   Lize, Yannick Keith  

    We describe a polarization dependent formalism for DPSK and DQPSK receivers and show that the combined effect of PDL and PDFS cannot be decoupled making the birefringence axes non-orthogonal and independent of PDL axes.
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  • Comparative physiologic effects of noninvasive assist-control and pressure support ventilation in acute hypercapnic respiratory failure

    Girault, Christophe   Richard, Jean-Christophe   Chevron, Virginie   Tamion, Fabienne   Pasquis, Pierre   Leroy, Jacques   Bonmarchand, Guy  

    Study objective: To compare the effects of noninvasive assist-control ventilation (ACV) and pressure support ventilation (PSV) by nasal mask on respiratory physiologic parameters and comfort in acute hypercapnic respiratory failure (AHRF). Design: A prospective randomized study. Setting: A medical ICU. Patients and interventions: Fifteen patients with COPD and AHRF were consecutively and randomly assigned to two noninvasive ventilation (NIV) sequences with ACV and PSV mode, spontaneous breathing (SB) via nasal mask being used as control. ACV and PSV settings were always subsequently adjusted according to patient's tolerance and air leaks. Fraction of inspired oxygen did not change between the sequences. Measurements and results: ACV and PSV mode strongly decreased the inspiratory effort in comparison with SB. The total inspiratory work of breathing (WOBinsp) expressed as WOBinsp/tidal volume (VT) and WOBinsp/respiratory rate (RR), the pressure time product (PTP), and esophageal pressure variations (Apes) were the most discriminant parameters (p lt 0.001). ACV most reduced WOBinsp/VT (P lt 0.05), Apes (p lt 0.05), and PTP (0.01) compared with PSV mode. The surface diaphragmatic electromyogram activity was also decreased gt 32% as compared with control values (p lt 0.01), with no difference between the two modes. Simultaneously, NIV significantly improved breathing pattern (p lt 0.01) with no difference between ACV and PSV for VT, RR, minute ventilation, and total cycle duration. As compared to SB, respiratory acidosis was similarly improved by both modes. The respiratory comfort assessed by visual analog scale was less with ACV (57.23 +- 30.12 mm) than with SB (75.15 +- 18.25 mm) (p lt 0.05) and PSV mode (81.62 +- 25.2 mm) (p lt 0.01) in our patients. Conclusions: During NIV for AHRF using settings adapted to patient's clinical tolerance and mask air leaks, both ACV and PSV mode provide respiratory muscle rest and similarly improve breathing pattern and gas exchange. However, these physiologic effects are achieved with a lower inspiratory workload but at the expense of a higher respiratory discomfort with ACV than with PSV mode.
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