Biomedical subjects

Marc Gainnier

Publications and source records attributed to Marc Gainnier.

18 recordsLinked to original sources

PubMed2007

High-frequency oscillatory ventilation following prone positioning prevents a further impairment in oxygenation.

OBJECTIVE: The improvement in oxygenation with prone positioning is not persistent when patients with acute respiratory distress syndrome (ARDS) are turned supine. High-frequency oscillatory ventilation (HFOV) aims to maintain an open lung volume by the application of a constant mean airway pressure. The aim of this study was to show that HFOV is able to prevent the impairment in oxygenation when ARDS patients are turned back from the prone to the supine position. DESIGN: Prospective, comparative randomized study. SETTING: A medical intensive care unit. PATIENTS: Forty-three ARDS patients with a Pao2/Fio2 ratio <150 at positive end-expiratory pressure > or =5 cm H2O. INTERVENTIONS: After an optimization period, the patients were assigned to one of three groups: a) conventional lung-protective mechanical ventilation in the prone position (12 hrs) followed by a 12-hr period of conventional lung-protective mechanical ventilation in the supine position (CV(prone)-CV(supine)); b) conventional lung-protective mechanical ventilation in the supine position (12 hrs) followed by HFOV in the supine position (12 hrs) (CV(supine)-HFOV(supine)); or c) conventional lung-protective mechanical ventilation in the prone position (12 hrs) followed by HFOV in the supine position (CV(prone)-HFOV(supine) group). MEASUREMENTS AND MAIN RESULTS: Pao2/Fio2 ratio was higher at the end of the study period in the CV(prone)-HFOV(supine) group than in the CV(prone)-CV(supine) group (p < .02). Venous admixture at the end of the study period was lower in the CV(prone)-HFOV(supine) group than in the two other groups. CONCLUSIONS: HFOV maintained the improvement in oxygenation related to prone positioning when ARDS patients were returned to the supine position.

Aged↗

PubMed2006

Generation of a single pulmonary pressure-volume curve does not durably affect oxygenation in patients with acute respiratory distress syndrome.

INTRODUCTION: 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. METHOD: 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 curve using a 2 l super syringe (PVSS; insufflated volume = 1824 +/- 381 ml, plateau pressure = 46 +/- 9 cmH2O); and generation of a PV curve using the constant flow method on the ventilator (PVCF; insufflated volume = 1120 +/- 115 ml in zero end-expiratory pressure after 20 s expiratory pause, plateau pressure = 46 +/- 11 cmH2O). The maximal airway pressure allowed during PV measurement was 60 cmH2O. PEEP was set to 10 cmH2O immediately after PV measurement. Partial arterial oxygen tension (Pao2), partial carbon dioxide tension (Paco2) and mean arterial pressure were recorded each minute. RESULTS: PV measurement did not significantly affect Pao2, Paco2, mean arterial pressure and lung mechanics. Two patients exhibited a sustained increase in Pao2 by more than 20% after PVCF (>60 minutes). Two patients exhibited a decrease in Pao2 by more than 20% after PVSS, which was sustained in one. These latter patients had an upper inflection point identified on the PV curve. After PVSS, Paco2 increased by more than 10 mmHg in two patients and returned to baseline values after 15 minutes. One patient exhibited a decrease in mean arterial pressure by more than 10 mmHg for less than 5 minutes after PVSS and one patient after PVCF. CONCLUSION: Evaluation of the effects of a strategy aimed at improving oxygenation can be reliably recorded early after a single PV measurement that is not followed by a change in PEEP level. PV measurement using the constant flow method improves oxygenation in a limited number of patients.

Adult↗

PubMed2006

[Crohn disease and abdominal tuberculosis: complications related to a diagnostic error].

INTRODUCTION: We report the case of a patient with abdominal tuberculosis initially treated as Crohn disease. CASE: A 50-year-old man, diagnosed with Crohn disease, was admitted to the intensive care unit for acute respiratory failure. After a new diagnosis of pulmonary and ileocecal tuberculosis and appropriate treatment for it, he improved. DISCUSSION: It is difficult - but essential - to differentiate intestinal tuberculosis and Crohn disease, for the immune suppression necessary to treat the latter can induce severe complications of the former. Management of intestinal tuberculosis is primarily medical, with surgery reserved for complications such as obstruction, fistulization, perforation, and bleeding.

Antitubercular Agents↗

PubMed2006

Neuromuscular blocking agents decrease inflammatory response in patients presenting with acute respiratory distress syndrome.

OBJECTIVE: To evaluate the effects of neuromuscular blocking agents (NMBAs) on pulmonary and systemic inflammation in patients with acute respiratory distress syndrome ventilated with a lung-protective strategy. DESIGN: Multiple-center, prospective, controlled, and randomized trial. SETTING: One medical and two medical-surgical intensive care units. PATIENTS: A total of 36 patients with acute respiratory distress syndrome (Pao2/Fio2 ratio of < or =200 at a positive end-expiratory pressure of > or =5 cm H2O) were included within 48 hrs of acute respiratory distress syndrome onset. INTERVENTIONS: Patients were randomized to receive conventional therapy plus placebo (n = 18) or conventional therapy plus NMBAs (n = 18) for 48 hrs. Both groups were ventilated with a lung-protective strategy (tidal volume between 4 and 8 mL/kg ideal body weight, plateau pressure of < or =30 cm H2O). MEASUREMENTS AND MAIN RESULTS: Bronchoalveolar lavages and blood samples were performed, before randomization and at 48 hrs, to determine the concentrations of tumor necrosis factor-alpha, interleukin (IL)-1beta, IL-6, and IL-8. Pao2/Fio2 ratio was evaluated before randomization and at 24, 48, 72, 96, and 120 hrs. A decrease over time in IL-8 concentrations (p = .034) was observed in the pulmonary compartment of the NMBA group. At 48 hrs after randomization, pulmonary concentrations of IL-1beta (p = .005), IL-6 (p = .038), and IL-8 (p = .017) were lower in the NMBA group as compared with the control group. A decrease over time in IL-6 (p = .05) and IL-8 (p = .003) serum concentrations was observed in the NMBA group. At 48 hrs after randomization, serum concentrations of IL-1beta (p = .037) and IL-6 (p = .041) were lower in the NMBA group as compared with the control group. A sustained improvement in Pao2/Fio2 ratio was observed and was reinforced in the NMBA group (p < .001). CONCLUSION: Early use of NMBAs decrease the proinflammatory response associated with acute respiratory distress syndrome and mechanical ventilation.

Cytokines↗

PubMed2006

Clinical review: use of helium-oxygen in critically ill patients.

Use of helium-oxygen (He/O2) mixtures in critically ill patients is supported by a reliable and well understood theoretical rationale and by numerous experimental observations. Breathing He/O2 can benefit critically ill patients with severe respiratory compromise mainly by reducing airway resistance in obstructive syndromes such as acute asthma and decompensated chronic obstructive pulmonary disease. However, the benefit from He/O2 in terms of respiratory mechanics diminishes rapidly with increasing oxygen concentration in the gaseous mixture. Safe use of He/O2 in the intensive care unit requires specific equipment and supervision by adequately experienced personnel. The available clinical data on inhaled He/O2 mixtures are insufficient to prove that this therapy has benefit with respect to outcome variables. For these reasons, He/O2 is not currently a standard of care in critically ill patients with acute obstructive syndromes, apart from in some, well defined situations. Its role in critically ill patients must be more precisely defined if we are to identify those patients who could benefit from this therapeutic approach.

Critical Illness↗

PubMed2005

Helium-oxygen decreases inspiratory effort and work of breathing during pressure support in intubated patients with chronic obstructive pulmonary disease.

OBJECTIVE: To evaluate the impact of helium-oxygen (He/O2) on inspiratory effort and work of breathing (WOB) in intubated COPD patients ventilated with pressure support. DESIGN AND SETTING: Prospective crossover interventional study in the medical ICU of a university hospital. PATIENTS AND PARTICIPANTS: Ten patients. INTERVENTIONS: Sequential inhalation (30 min each) of three gas mixtures: (a) air/O2, (b) He/O2 (c) air/O2, at constant FIO2 and level of pressure support. MEASUREMENTS AND RESULTS: Inspiratory effort and WOB were determined by esophageal and gastric pressure. Throughout the study pressure support and FIO2 were 14+/-3 cmH2O and 0.33+/-0.07 respectively. Compared to Air/O2, He/O2 reduced the number of ineffective breaths (4+/-5 vs. 9+/-5 breaths/min), intrinsic PEEP (3.1+/-2 vs. 4.8+/-2 cmH2O), the magnitude of negative esophageal pressure swings (6.7+/-2 vs. 9.1+/-4.9 cmH2O), pressure-time product (42+/-37 vs. 67+/-65 cmH2O s(-1) min(-1)), and total WOB (11+/-3 vs. 18+/-10 J/min). Elastic (6+/-1 vs. 10+/-6 J/min) and resistive (5+/-1 vs. 9+/-4 J/min) components of the WOB were decreased by He/O2. CONCLUSIONS: In intubated COPD patients ventilated with pressure support He/O2 reduces intrinsic PEEP, the number of ineffective breaths, and the magnitude of inspiratory effort and WOB. He/O2 could prove useful in patients with high levels of PEEPi and WOB ventilated in pressure support, for example, during weaning.

Aged↗

PubMed2005

Impact of expiratory trigger setting on delayed cycling and inspiratory muscle workload.

RATIONALE: During pressure-support ventilation, the ventilator cycles into expiration when inspiratory flow decreases to a given percentage of peak inspiratory flow ("expiratory trigger"). In obstructive disease, the slower rise and decrease of inspiratory flow entails delayed cycling, an increase in intrinsic positive end-expiratory pressure, and nontriggering breaths. OBJECTIVES: We hypothesized that setting expiratory trigger at a higher than usual percentage of peak inspiratory flow would attenuate the adverse effects of delayed cycling. METHODS: Ten intubated patients with obstructive disease undergoing pressure support were studied at expiratory trigger settings of 10, 25, 50, and 70% of peak inspiratory flow. MEASUREMENTS: Continuous recording of diaphragmatic EMG activity with surface electrodes, and esophageal and gastric pressures with a dual-balloon nasogastric tube. MAIN RESULTS: Compared with expiratory trigger 10, expiratory trigger 70 reduced the magnitude of delayed cycling (0.25 +/- 0.18 vs. 1.26 +/- 0.72 s, p < 0.05), intrinsic positive end-expiratory pressure (4.8 +/- 1.9 vs. 6.5 +/- 2.2 cm H(2)O, p < 0.05), nontriggering breaths (2 +/- 3 vs. 9 +/- 5 breaths/min, p < 0.05), and triggering pressure-time product (0.9 +/- 0.8 vs. 2.1 +/- 0.7 cm H2O . s, p < 0.05). CONCLUSIONS: Setting expiratory trigger at a higher percentage of peak inspiratory flow in patients with obstructive disease during pressure support improves patient-ventilator synchrony and reduces inspiratory muscle effort. Further studies should explore whether these effects can influence patient outcome.

Aged↗

PubMed2005

Influence of support on intra-abdominal pressure, hepatic kinetics of indocyanine green and extravascular lung water during prone positioning in patients with ARDS: a randomized crossover study.

INTRODUCTION: Prone positioning (PP) on an air-cushioned mattress is associated with a limited increase in intra-abdominal pressure (IAP) and an absence of organ dysfunction. The respective influence of posture by itself and the type of mattress on these limited modifications during the PP procedure remains unclear. The aim of this study was to evaluate whether the type of support modifies IAP, extravascular lung water (EVLW) and the plasma disappearance rate of indocyanine green (PDRICG) during PP. METHODS: A prospective, randomized, crossover study of 20 patients with acute respiratory distress syndrome (ARDS) was conducted in a medical intensive care unit in a teaching hospital. Measurements were made at baseline and repeated after 1 and 6 hours of two randomized periods of 6 hours of PP with one of two support types: conventional foam mattress or air-cushioned mattress. RESULTS: After logarithmic transformation of the data, an analysis of variance (ANOVA) showed that IAP and PDRICG were significantly influenced by the type of support during PP with an increase in IAP (P < 0.05 by ANOVA) and a decrease in PDRICG on the foam mattress (P < 0.05 by ANOVA). Conversely, the measurements of EVLW did not show significant modification between the two supports whatever the posture. The ratio of the arterial oxygen tension to the fraction of inspired oxygen significantly increased in PP (P < 0.0001 by ANOVA) without any influence of the support. CONCLUSION: In comparison with a conventional foam mattress, the use of an air-cushioned mattress limited the increase in IAP and prevented the decrease in PDRICG related to PP in patients with ARDS. Conversely, the type of support did not influence EVLW or oxygenation.

Adult↗

PubMed2005

Effects of helium-oxygen mixtures on endotracheal tubes: an in vitro study.

QUESTION: To determine flow pattern and critical Reynolds numbers in endotracheal tubes submitted to different helium-oxygen mixtures under laboratory conditions. MATERIALS AND METHODS: Flow-pressure relationships were performed for seven endotracheal tubes (rectilinear position, entry length applied) with distal end open to atmosphere (predicted internal diameters: 6-9 mm). Nine helium-oxygen mixtures were tested, with FIHe varying from zero to 0.78 (increment: 10%). Nine flows were tested, with rates varying from 0.25 to 1.60 l s(-1) (increment: 0.15 l s(-1)). Gas flow resistance was calculated, and for each endotracheal tube, a Moody diagram was realised. Flow regime and critical Reynolds numbers were then determined (fully established laminar, nonestablished laminar, smooth turbulent, or rough). RESULTS: Even low concentration of helium in inspiratory mixture reduces endotracheal tubes resistance. Effect is maximal for high flows, small tube and high FIHe. Critical Reynolds numbers are inversely correlated to tube diameter. ANSWER: Under laboratory conditions, flow pattern in endotracheal tubes varies from fully established laminar to rough. Knowledge of the critical Reynolds numbers allows correct application of fluid mechanic formula when studying tube or gaseous mixture effects on respiratory mechanisms.

Adult↗

PubMed2005

Comparison of prone positioning and high-frequency oscillatory ventilation in patients with acute respiratory distress syndrome.

OBJECTIVE: Both prone position and high-frequency oscillatory ventilation (HFOV) have the potential to facilitate lung recruitment, and their combined use could thus be synergetic on gas exchange. Keeping the lung open could also potentially be lung protective. The aim of this study was to compare physiologic and proinflammatory effects of HFOV, prone positioning, or their combination in severe acute respiratory distress syndrome (ARDS). DESIGN: : Prospective, comparative randomized study. SETTING: A medical intensive care unit. PATIENTS: Thirty-nine ARDS patients with a Pao2/Fio2 ratio <150 mm Hg at positive end-expiratory pressure > or =5 cm H2O. INTERVENTIONS: After 12 hrs on conventional lung-protective mechanical ventilation (tidal volume 6 mL/kg of ideal body weight, plateau pressure not exceeding the upper inflection point, and a maximum of 35 cm H2O; supine-CV), 39 patients were randomized to receive one of the following 12-hr periods: conventional lung-protective mechanical ventilation in prone position (prone-CV), HFOV in supine position (supine-HFOV), or HFOV in prone position (prone-HFOV). MEASUREMENTS AND MAIN RESULTS: Prone-CV (from 138 +/- 58 mm Hg to 217 +/- 110 mm Hg, p < .0001) and prone-HFOV (from 126 +/- 40 mm Hg to 227 +/- 64 mm Hg, p < 0.0001) improved the Pao2/Fio2 ratio whereas supine-HFOV did not alter the Pao2/Fio2 ratio (from 134 +/- 57 mm Hg to 138 +/- 48 mm Hg). The oxygenation index ({mean airway pressure x Fio2 x 100}/Pao2) decreased in the prone-CV and prone-HFOV groups and was lower than in the supine-HFOV group. Interleukin-8 increased significantly in the bronchoalveolar lavage fluid (BALF) in supine-HFOV and prone-HFOV groups compared with prone-CV and supine-CV. Neutrophil counts were higher in the supine-HFOV group than in the prone-CV group. CONCLUSIONS: Although HFOV in the supine position does not improve oxygenation or lung inflammation, the prone position increases oxygenation and reduces lung inflammation in ARDS patients. Prone-HFOV produced similar improvement in oxygenation like prone-CV but was associated with higher BALF indexes of inflammation. In contrast, supine-HFOV did not improve gas exchange and was associated with enhanced lung inflammation.

Adult↗

PubMed2005

Early antibiotic treatment for BAL-confirmed ventilator-associated pneumonia: a role for routine endotracheal aspirate cultures.

STUDY OBJECTIVES: To test whether routine quantitative cultures of endotracheal aspirates obtained before the onset of ventilator-associated pneumonia (VAP) could help to predict the causative microorganisms and to select early appropriate antimicrobial therapy before obtaining BAL culture results. DESIGN: Prospective observational study. SETTING: French medical ICU. PATIENTS: A total of 299 patients received mechanical ventilation for at least 48 h. INTERVENTIONS: Endotracheal aspiration (EA) was performed twice weekly in all mechanically ventilated patients. A diagnosis of VAP was made by BAL culture. Only the EA performed just before the suspicion of VAP (EA-pre) were evaluated. This strategy (ie, the EA-pre-based strategy) was compared with an antibiotic therapy that would have been prescribed if the recommendations of both the American Thoracic Society (ATS) and Trouillet et al (Am J Respir Crit Care Med 1998; 157:531-539) had been applied. MEASUREMENTS AND RESULTS: VAP was diagnosed (by BAL culture) in 41 of the 75 patients in whom BAL was performed. Among the 41 BAL specimens that were positive for VAP, EA-pre had identified the same microorganisms (with the same antibiotic resistance patterns) in 34 cases (83%). In one case, EA-pre was not available at the time BAL was performed (a case of early-onset VAP), but the empiric antibiotic therapy was adequate. While EA-pre did not give the same results as the BAL culture, the antibiotic therapy based on the results of the EA-pre was adequate in four other cases. Finally, antibiotic therapy was delayed in only two cases. Antibiotic treatment was therefore adequate in 38 of the 40 assessable cases (95%). If the Trouillet-based strategy had been used, the antibiotic treatment would have been adequate in 34 of the 41 cases (83%; p = 0.15 [vs EA-pre strategy]). Based on the ATS classification, the antibiotic treatment would have been adequately prescribed in only 28 of the 41 cases (68%; p = 0.005 [vs EA-pre strategy]). CONCLUSIONS: Routine EA performed twice a week makes it possible to prescribe adequate antibiotic therapy (while waiting for BAL culture results) in 95% of the patients in whom a VAP is ultimately diagnosed by BAL culture.

Adult↗

PubMed2004

Effect of neuromuscular blocking agents on gas exchange in patients presenting with acute respiratory distress syndrome.

OBJECTIVE: To evaluate the effects of a 48-hr neuromuscular blocking agents (NMBA) infusion on gas exchange over a 120-hr time period in patients with acute respiratory distress syndrome. DESIGN: Multiple center, prospective, controlled, and randomized trial. SETTING: Four adult medical or mixed medical-surgical intensive care units. PATIENTS: A total of 56 patients with acute respiratory distress syndrome with a PaO2/FiO2 ratio of <150 at a positive end-expiratory pressure of > or =5 cm H2O. INTERVENTIONS: After randomization, patients received either conventional therapy without NMBA (control group) or conventional therapy plus NMBA for the next 48 hrs. The initial ventilator mode was volume-assist/control. The ventilator remained on assist-control mode throughout the initial 48-hr period in both groups. Tidal volume was 6-8 mL/kg ideal body weight. MEASUREMENTS AND MAIN RESULTS: When analyzed for the entire 120 hrs, there was a significant effect of the NMBA on the course of PaO2/FiO2 ratio (p =.021). Separate comparisons at each time point indicated that patients randomized to the NMBA group had a higher PaO2/FiO2 at 48, 96, and 120 hrs after randomization. Moreover, a decrease of positive end-expiratory pressure (p =.036) was only found in the NMBA group. Two-way repeated-measures analysis of variance exhibited a decrease in positive end-expiratory pressure over time (p =.036). Concerning short-term effects, there was no modification of PaO2/FiO2 ratio 1 hr after randomization in either group. Only one patient (from the control group) developed pneumothorax. CONCLUSIONS: Use of NMBA during a 48-hr period in patients with acute respiratory distress syndrome is associated with a sustained improvement in oxygenation.

Acute Disease↗

PubMed2004

Expiratory trigger setting in pressure support ventilation: from mathematical model to bedside.

OBJECTIVE: To evaluate the feasibility of relying on a mathematical model to adjust the optimal level of expiratory trigger, materialized by the ratio of inspiratory flow at the end of inspiratory effort (V'ti) and peak inspiratory flow (V'peak), or V'ti/V'peak, during pressure support, by comparing its predicted values with those measured in intubated patients. DESIGN: Prospective observational study. SETTING: Medical intensive care unit, university hospital. PATIENTS: There were 28 intubated patients undergoing pressure support. INTERVENTIONS: Pressure support as set by the clinician in charge. MEASUREMENTS AND MAIN RESULTS: A significant correlation was found between predicted and measured V'ti/V'peak ratios (r =.70; p <.001; mean +/- sd difference, -0.025 +/- 0.07; 95% confidence interval, -0.161 to 0.111). Overall, delayed cycling occurred in obstructive conditions, the delay increasing as obstructive disease was more severe. CONCLUSIONS: A significant correlation was observed between predicted values of V'ti/V'peak and those values measured in patients undergoing pressure support. These findings should stimulate further research into the possible applications of this mathematical model to optimize expiratory trigger setting. Furthermore, our findings suggest that expiratory trigger should be adjustable and provide a wider range of cutoff levels than that which is currently available.

Feasibility Studies↗

PubMed2003

Helium-oxygen reduces work of breathing in mechanically ventilated patients with chronic obstructive pulmonary disease.

OBJECTIVE: To evaluate whether helium-oxygen mixture reduces inspiratory work of breathing (WOB) in sedated, paralyzed, and mechanically ventilated patients with acute exacerbation of chronic obstructive pulmonary disease (COPD). DESIGN AND SETTING: Open, prospective, randomized, crossover study in the medical intensive care unit in a university hospital. PATIENTS AND PARTICIPANTS: 23 patients admitted for acute exacerbation of COPD and mechanically ventilated. MEASUREMENTS: Total WOB (WOBt), elastic WOB (WOBel), resistive WOB (WOBres), and WOB due to PEEPi (WOBPeepi) were measured. Static intrinsic positive end expiratory pressure (PEEPi), static compliance (Crs), inspiratory resistance (Rins), inspiratory (tinsp) and expiratory time constant (texp) were also measured. These variables were compared between air-oxygen and helium-oxygen mixtures. RESULTS: WOBt significantly decreased with helium-oxygen (2.34+/-1.04 to 1.85+/-1.01 J/l, p<0.001). This reduction was significant for WOBel (1.02+/-0.61 J/l to 0.87+/-0.47, p<0.01), WOBPeepi (0.77+/-0.38 J/l to 0.54+/-0.38, p<0.001), and WOBres (0.55+/-0.19 J/l to 0.44+/-0.24, p<0.05). PEEPi, Rins, tinsp and texp significantly decreased. Crs was unchanged. CONCLUSIONS: Helium-oxygen mixture decreases WOB in mechanically ventilated COPD patients. Helium-oxygen mixture could be useful to reduce the burden of ventilation.

Aged↗

PubMed2003

Prone position and positive end-expiratory pressure in acute respiratory distress syndrome.

OBJECTIVE: To determine whether positive end-expiratory pressure (PEEP) and prone position present a synergistic effect on oxygenation and if the effect of PEEP is related to computed tomography scan lung characteristic. DESIGN: Prospective randomized study. SETTING: French medical intensive care unit. PATIENTS: Twenty-five patients with acute respiratory distress syndrome. INTERVENTIONS: After a computed tomography scan was obtained, measurements were performed in all patients at four different PEEP levels (0, 5, 10, and 15 cm H2O) applied in random order in both supine and prone positions. MEASUREMENTS AND MAIN RESULTS: Analysis of variance showed that PEEP (p <.001) and prone position (p <.001) improved oxygenation, whereas the type of infiltrates did not influence oxygenation. PEEP and prone position presented an additive effect on oxygenation. Patients presenting diffuse infiltrates exhibited an increase of Pao2/Fio2 related to PEEP whatever the position, whereas patients presenting localized infiltrates did not have improved oxygenation status when PEEP was increased in both positions. Prone position (p <.001) and PEEP (p <.001) reduced the true pulmonary shunt. Analysis of variance showed that prone position (p <.001) and PEEP (p <.001) reduced the true pulmonary shunt. The decrease of the shunt related to PEEP was more pronounced in patients presenting diffuse infiltrates. A lower inflection point was identified in 22 patients (88%) in both supine and prone positions. There was no difference in mean lower inflection point value between the supine and the prone positions (8.8 +/- 2.7 cm H2O vs. 8.4 +/- 3.4 cm H2O, respectively). CONCLUSIONS: PEEP and prone positioning present additive effects. The prone position, not PEEP, improves oxygenation in patients with acute respiratory distress syndrome with localized infiltrates.

Adult↗

PubMed2003

Cardiopulmonary effects of lipid emulsions in patients with ARDS.

STUDY OBJECTIVES: Lipid emulsions have been suspected of inducing certain modifications in gas exchange and pulmonary hemodynamics. The aim of this prospective study was to evaluate the hemodynamic and pulmonary effects of two lipid emulsions. DESIGN: Prospective, randomized, double-blind, crossover study. SETTING: Medical and surgical ICU in a French university hospital. PATIENTS: Eighteen patients presenting ARDS. INTERVENTIONS: Each patient received a 6-h infusion of a 20% fat emulsion containing 100% long-chain triglycerides (LCTs) and a 6-h infusion of 50% LCTs/50% medium-chain triglycerides (MCTs) 20% lipid emulsion at the rate of 1.0 mL/kg/h. An 18-h period with no lipids separated the two periods. An additional 18-h period after the end of the second lipid emulsion administration was observed prior to the final measurements. MEASUREMENTS AND RESULTS: The MCT/LCT emulsion increased the PaO(2)/fraction of inspired oxygen (FIO(2)) ratio (p = 0.005) compared with LCT emulsion alone. The mean (+/- SD) PaO(2)/FIO(2) ratio increased from 165 +/- 55 to 191 +/- 64 mm Hg after 1 h of LCT/MCT administration (p < 0.03), and to 175 +/- 46 mm Hg after 6 h. Moreover, there was an increase in oxygen delivery after 6 h of LCT/MCT administration (p < 0.001 vs baseline). While a time-related increase in mean pulmonary artery pressure (p = 0.012) during lipid administration was found, no effect of the kind of lipid emulsion was observed. The time-related increase in cardiac index (p = 0.002) was more marked when the patients received the LCT/MCT emulsion (p = 0.002). Pulmonary vascular resistances were not affected by the kind of lipid emulsion. CONCLUSIONS: The present work showed that while the LCT emulsion induced no deleterious effects on oxygenation in ARDS patients, the LCT/MCT emulsion improved the PaO(2)/FIO(2) ratio and had a further beneficial effect on oxygen delivery.

Cross-Over Studies↗

PubMed2002

The post-exercise oxidative stress is depressed by acetylsalicylic acid.

In order to assess whether oxidative stress occurs after fatiguing dynamic contractions of a small forearm muscle group, we estimated the kinetics of changes in some of its biomarkers (thiobarbituric acid reactive substances or TBARS; plasma reduced ascorbic acid or RAA; erythrocyte reduced glutathione or GSH). We also tested the hypothesis that acetylsalicylic acid (ASA) may compete with endogenous radical targets, attenuating the post-exercise oxidative stress. Seven male subjects successively performed a 3-min dynamic handgrip exercise with the dominant and then the contralateral forearm. Blood samples were taken from an antecubital vein in each exercising forearm. Biochemical analyses, including the concentration measurements of lactic acid, potassium, and oxidative stress markers were performed at rest and then during the 30-min period of recovery following each exercise. The same day, exercises were repeated after ingestion of a single dose (10 mg/kg) of ASA, and the same exercises were performed after a 3-day ASA treatment (30 mg/kg/day). In control condition, the changes in TBARS, RAA and GSH were already significant immediately after the end of the forearm exercise. They culminated after 5 min, and control values were recovered by a 30-min rest period. We verified that repeated bouts failed to alter the post-exercise variations. ASA did not modify the lactic acid production significantly, though the 3-day ASA treatment significantly reduced the efflux of potassium (-74%, P < 0.05), and the post-exercise variations of TBARS (-45%, P < 0.01), RAA (-44%, P < 0.01) and GSH (-48%, P < 0.01). These results suggest that the dynamic handgrip exercise is a good model for studying the post-exercise oxidative stress and also that ASA seems to offer an efficient protection against oxidative stress and the changes in membrane permeability to potassium.

Adult↗

PubMed2002

Can the tomographic aspect characteristics of patients presenting with acute respiratory distress syndrome predict improvement in oxygenation-related response to the prone position?

BACKGROUND: In some patients with acute respiratory distress syndrome, the prone position is able to improve oxygenation, whereas in others it is not. It could be hypothesized that the more opacities that are present in dependent regions of the lung when the patient is in the supine position, the better the improvement in oxygenation is observed when the patients are turned prone. Therefore, we conducted a prospective study to identify computed tomographic scan aspects that could accurately predict who will respond to the prone position. METHODS: We included 46 patients with acute respiratory distress syndrome (31 responders and 15 nonresponders). Computed tomographic scan was performed in the 6-h period preceding prone position. Blood gas analyses were performed before and at the end of the first 6-h period of prone position. RESULTS: Arterial oxygen partial pressure/fraction of inspired oxygen increased from 117 +/- 42 (mean +/- SD) in the supine position to 200 +/- 76 mmHg in the prone position (P < 0.001). There were 31 responders and 15 nonresponders. There was a vertebral predominance of the opacities (P < 0.0001). However, there was no difference between responders and nonresponders. When only the amount of consolidated lung located under the heart was evaluated, there was more consolidated tissue under the heart relative to total lung area in nonresponders than in responders (P = 0.01). CONCLUSIONS: There are no distinctive morphologic features in the pattern of lung disease measured by computed tomographic scanning performed with the patient in the supine position that can predict response to the prone position.

Aged↗