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 (30min 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±3cmH2O 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±2cmH2O), the magnitude of negative esophageal pressure swings (6.7±2 vs. 9.1±4.9cmH2O), pressure-time product (42±37 vs. 67±65cmH2Os−1min−1), and total WOB (11±3 vs. 18±10J/min). Elastic (6±1 vs. 10±6J/min) and resistive (5±1 vs. 9±4J/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 weanin

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 (PDR(ICG)) 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 PDR(ICG )were significantly influenced by the type of support during PP with an increase in IAP (P < 0.05 by ANOVA) and a decrease in PDR(ICG )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 PDR(ICG )related to PP in patients with ARDS. Conversely, the type of support did not influence EVLW or oxygenation

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 cmH(2)O and a positive end-expiratory pressure [PEEP] of 10 cmH(2)O. 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 (PV(SS); insufflated volume = 1824 ± 381 ml, plateau pressure = 46 ± 9 cmH(2)O); and generation of a PV curve using the constant flow method on the ventilator (PV(CF); insufflated volume = 1120 ± 115 ml in zero end-expiratory pressure after 20 s expiratory pause, plateau pressure = 46 ± 11 cmH(2)O). The maximal airway pressure allowed during PV measurement was 60 cmH(2)O. PEEP was set to 10 cmH(2)O immediately after PV measurement. Partial arterial oxygen tension (Pao(2)), partial carbon dioxide tension (Paco(2)) and mean arterial pressure were recorded each minute. RESULTS: PV measurement did not significantly affect Pao(2), Paco(2), mean arterial pressure and lung mechanics. Two patients exhibited a sustained increase in Pao(2 )by more than 20% after PV(CF )(>60 minutes). Two patients exhibited a decrease in Pao(2 )by more than 20% after PV(SS), which was sustained in one. These latter patients had an upper inflection point identified on the PV curve. After PV(SS), Paco(2 )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 PV(SS )and one patient after PV(CF). 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

Analyse corrélative des événements physiologiques, électrophysiologiques et biochimiques au cours du travail musculaire dynamique

AIX-MARSEILLE2-BU Méd/Odontol. (130552103) / SudocPARIS-BIUP (751062107) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Evaluation d'une chaîne de survie intra-hospitalière dédiée à la prise en charge des détresses vitales

AIX-MARSEILLE2-BU Méd/Odontol. (130552103) / SudocSudocFranceF

La fin de vie des insuffisants respiratoires chroniques : la dyspnée (aspects éthiques et épidémiologiques)

AIX-MARSEILLE2-BU Méd/Odontol. (130552103) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF