Non-invasive assessment of lung elastance in patients with acute respiratory distress syndrome.

BACKGROUND: Chest wall mechanics can be abnormal in patients with acute respiratory disease syndrome (ARDS). Therefore, partitioning respiratory system between lungs and chest wall at the bedside is useful to optimize ventilator settings. A non-invasive method for assessing lung elastance (EL), called lung barometry, was previously described on an animal model. METHODS: This prospective study was designed to compare EL assessed by lung barometry (ELLB) versus esophageal pressure (ELPeso). In sedated, paralyzed patients, PEEP was progressively increased from 5 to 40cmH2O then decreased from 40 to 5cmH2O by step of 5cmH2O every two minutes. ELLB was assessed for each step as the ratio between the change in PEEP and the induced end-expiratory lung volume change measured by direct spirometry. ELPeso was calculated from esophageal pressure measurement at each PEEP. EL and the ratio between EL and respiratory system elastance (ERS) calculated with the two methods were compared. RESULTS: Twenty six adult patients with early onset moderate or severe ARDS were included. There was a linear correlation between ELLB and ELPeso during the increase and decrease of PEEP (R²=0.26 and 0.42, respectively). Concordance using Bland and Altman method demonstrated bias and large limits of agreement during the increase (-0.5 cmH2O/L; -25 to 24 cmH2O/L) and during the decrease in PEEP (-0.3 cmH2O/L; -21 to 20 cmH2O/L). There were no linear correlation between ELLB/ERS and ELPeso/ERS during the increase and the decrease of PEEP (R²=0.00; R²=0.00, respectively). CONCLUSION: In ARDS patients, lung barometry method cannot be used instead of the esophageal pressure measurement to assess EL.

[Efficacy, safety and cost of sedation with sevoflurane in intensive care unit]. / Efficacité, tolérance et coût d'une sédation par sévoflurane en réanimation.

OBJECTIVES: To study efficacy, systemic and cerebral haemodynamic, and cost of sedation with sevoflurane after midazolam failure. STUDY DESIGN: Prospective observational study in a mixed intensive care unit. PATIENTS AND METHODS: Mechanically ventiled patients in whom deep sedation failed (Ramsay score<5 despite midazolam 10mg/h and fentanyl 400µg/h) were enrolled. Sedation with sevoflurane and fentanyl (200µg/h) was performed during 48 hours. Sevoflurane was administered with a dedicated filter (AnaConDa™) and sevoflurane infusion rate was adjusted in order to achieve a Ramsay score ≥5. Ramsay score, mean arterial blood pressure, norepinephrine dose/24h, intracranial pressure and cerebral perfusion pressure in patients with brain injury were measured. Directs costs for sedation were calculated. An analysis of variance for repeated measures compared values between D0 (intravenous sedation), D1 and D2 (inhaled sedation). RESULTS: Twenty-five patients (age=51 [38-63], SAPS II=43 [33-49]) were enrolled. Ramsay score was 4 [4,5] at D0 and 6 [6] at D1 and D2 (P<0.05 vs D0). Mean arterial pressure was significantly lower at D1 (80 [73-86] mmHg) as compared to D0 (84 [77-92] mmHg) and D2 (84 [78-91] mmHg) (P<0,05). Norepinephrine consumption was lower at D2 as compared to D1 (P<0,05). Intracranial pressure was lower at D1 (9 [5-13] mmHg) and D2 (11 [7-15] mmHg) as compared to D0 (12 [7-17] mmHg) (P<0.05). PPC was stable at D1 and increased at D2. Directs costs were significantly increased with sevoflurane. CONCLUSION: Sevoflurane is an effective and safe alternative to midazolam in ICU patients associated with a moderate increase in costs.