Being Convinced and Taking Responsibility: A Qualitative Study of Family Members' Experience of Organ Donation Decision and Bereavement After Brain Death.

OBJECTIVES: Family members of brain dead patients experience an unprecedented situation in which not only they are told that their loved one is dead but are also asked to consider organ donation. The objective of this qualitative study was to determine 1) what it means for family members to make the decision and to take responsibility, 2) how they interact with the deceased patient in the ICU, 3) how family members describe the impact of the process and of the decision on their bereavement process. DESIGN: Qualitative study using interviews with bereaved family members who were approached for organ donation after the death of their relative in the ICU (brain death). SETTING: Family members from 13 ICUs in France. SUBJECTS: Bereaved family members who were approached for organ donation after the death of their relative in the ICU (brain death). INTERVENTION: None. MEASUREMENTS AND RESULTS: Twenty-four interviews were conducted with 16 relatives of organ donor patients and with eight relatives of nonorgan donor patients. Three themes emerged: 1) taking responsibility-relatives explain how they endorse decisional responsibility but do not experience it as a burden, on the contrary; 2) ambiguous perceptions of death-two groups of relatives emerge: those for whom ambiguity hinders their acceptance of the patient's death; those for whom ambiguity is an opportunity to accept the death and say goodbye; and 3) donation as a comfort during bereavement. CONCLUSIONS: In spite of caregivers' efforts to focus organ donation discussions and decision on the patient, family members feel a strong decisional responsibility that is not experienced as a burden but a proof of their strong connection to the patient. Brain death however creates ambivalent experiences that some family members endure whereas others use as an opportunity to perform separation rituals. Last, organ donation can be experienced as a form of comfort during bereavement provided family members remain convinced their decision was right.

Transforming Growth Factor-ß1 in predicting early lung fibroproliferation in patients with acute respiratory distress syndrome.

BACKGROUND: Fibroproliferative repair phase of the acute respiratory distress syndrome (ARDS) is followed by a restitutio ad integrum of lung parenchyma or by an irreversible lung fibrosis and patients' death. Transforming Growth Factor-ß1 (TGF-ß1) is involved in collagen production and lung repair. We investigated whether alveolar TGF-ß1 was associated with the presence of fibroproliferation and the outcome of ARDS patients. METHODS: Sixty-two patients were included the first day of moderate-to-severe ARDS. Bronchoalveolar lavage fluid (BALF) was collected at day 3 (and day 7 when the patients were still receiving invasive mechanical ventilation) from the onset of ARDS. Survival was evaluated at day 60. TGF-ß1 was measured by immunoassay. The patients were classified as having lung fibroproliferation when the alveolar N-terminal peptide for type III procollagen (NT-PCP-III) measured on day 3 was > 9 µg/L as recently reported. The main objective of this study was to compare the alveolar levels of total TGF-ß1 according to the presence or not a lung fibroproliferation at day 3. RESULTS: Forty-three patients (30.6%) presented a fibroproliferation at day 3. BALF levels of total TGF-ß1 were not statistically different at day 3 (and at day 7) according to the presence or not lung fibroproliferation. Mortality at day 60 was higher in the group of patients with fibroproliferation as compared with patients with no fibroproliferation (68.4% vs. 18.6% respectively; p < 0.001). Total TGF-ß1 measured on BALF at day 3 was not associated with the outcome. Multiple logistic regression showed that the presence of lung fibroproliferation was associated with death. In contrast, TGF-ß1 was not independently associated with death. CONCLUSIONS: Pulmonary levels of TGF-ß1 during the first week of ARDS were not associated nor with the presence of fibroproliferation neither with death. TGF-ß1 should not be used as a biomarker to direct anti-fibrotic therapies.

Grief Symptoms in Relatives Who Experienced Organ Donation Requests in the ICU.

RATIONALE: Studies show that the quality of end-of-life communication and care have a significant impact on the living long after the death of a relative and have been implicated in the burden of psychological symptoms after the ICU experience. In the case of organ donation, the patient's relatives are centrally involved in the decision-making process; yet, few studies have examined the impact of the quality of communication on the burden of psychological symptoms after death. OBJECTIVES: To assess the experience of the organ donation process and grief symptoms in relatives of brain-dead patients who discussed organ donation in the ICU. METHODS: We conducted a multicenter longitudinal study in 28 ICUs in France. Participants were the relatives of brain-dead patients who were approached to discuss organ donation. Relatives were followed-up by phone at three time points: at 1 month, to complete a questionnaire describing their experience of the organ donation process; at 3 months, to complete the Hospital Anxiety and Depression Scale and the Impact of Event Scale-Revised; and at 9 months, to complete the Impact of Event Scale-Revised and the Inventory of Complicated Grief. MEASUREMENTS AND MAIN RESULTS: In total, 202 relatives of 202 patients were included, of whom 158 consented to and 44 refused organ donation. Interviews were conducted at 1, 3, and 9 months with 78%, 68%, and 58% of relatives, respectively. The overall experience of the organ donation process was significantly more burdensome for relatives of nondonors. They were more dissatisfied with communication (27% vs. 10%; P = 0.021), more often shocked by the request (65% vs. 19%; P < 0.0001), and more often found the decision difficult (53% vs. 27%; P = 0.017). However, there were no significant differences in grief symptoms measured at 3 and 9 months between the two groups. Understanding of brain death was associated with grief symptoms; our results show a higher prevalence of complicated grief symptoms among relatives who did not understand the brain death process than among those who did (75% vs. 46.1%; P = 0.026). CONCLUSIONS: Experience of the organ donation process varied between relatives of donor versus nondonor patients, with relatives of nondonors experiencing lower-quality communication, but the decision was not associated with subsequent grief symptoms. Importantly, understanding of brain death is a key element of the organ donation process for relatives.

Closed loop ventilation mode in Intensive Care Unit: a randomized controlled clinical trial comparing the numbers of manual ventilator setting changes.

BACKGROUND: There is an equipoise regarding closed-loop ventilation modes and the ability to reduce workload for providers. On one hand some settings are managed by the ventilator but on another hand the automatic mode introduces new settings for the user. METHODS: This randomized controlled trial compared the number of manual ventilator setting changes between a full closed loop ventilation and oxygenation mode (INTELLiVENT-ASV®) and conventional ventilation modes (volume assist control and pressure support) in Intensive Care Unit (ICU) patients. The secondary endpoints were to compare the number of arterial blood gas analysis, the sedation dose and the user acceptance. Sixty subjects with an expected duration of mechanical ventilation of at least 48 hours were randomized to be ventilated using INTELLiVENT-ASV® or conventional modes with a protocolized weaning. All manual ventilator setting changes were recorded continuously from inclusion to successful extubation or death. Arterial blood gases were performed upon decision of the clinician in charge. User acceptance score was assessed for nurses and physicians once daily using a Likert Scale. RESULTS: The number of manual ventilator setting changes per 24 h-period per subject was lower in INTELLiVENT-ASV® as compared to conventional ventilation group (5 [4-7] versus 10 [7-17]) manuals settings per subject per day [P<0.001]). The number of arterial blood gas analysis and the sedation doses were not significantly different between the groups. Nurses and physicians reported that INTELLiVENT-ASV® was significantly easier to use as compared to conventional ventilation (P<0.001 for nurses and P<0.01 for physicians). CONCLUSIONS: For mechanically ventilated ICU patients, INTELLiVENT-ASV® significantly reduces the number of manual ventilator setting changes with the same number of arterial blood gas analysis and sedation dose, and is easier to use for the caregivers as compared to conventional ventilation modes.

Efficiency and safety of a noninvasive therapeutic hypothermia protocol in cardiac arrest.

OBJECTIVES: Therapeutic hypothermia (TH) is part of the treatment strategy for comatose survivors of cardiac arrest (CA). The aim of our study was to evaluate the efficiency and the safety of a noninvasive and affordable cooling procedure applied to all types of CA in an ICU. STUDY DESIGN: This was a retrospective, observational, monocenter study. PATIENTS AND METHODS: In all patients remaining unconscious after CA, irrespective of their initial cardiac rhythm, TH was induced with a rapid intravenous infusion of 30 ml/kg ice-cold (4°C) saline fluid associated with external surface cooling involving ice packs and wet sheets. The body temperature was maintained between 32 and 34°C during 24 h using external surface cooling only. The patients were then passively rewarmed. RESULTS: Of 200 eligible patients, 145 were treated by TH; 104 patients completed the 24-h TH treatment. The primary cause of noninclusion or secondary exclusion was severe hemodynamic impairment. From induction, the median time to reach the target temperature was 167 min (47-300 min). During the protocol, 24 patients did not remain within the targeted temperature range. Adverse events included hypokalemia (44%), severe arrhythmia (13.8%), bleeding (4.8%), and seizure (1.4%). All patients presented hyperglycemia. The oxygen partial pressure to oxygen fractional concentration (PaO2/FiO2) ratio remained constant after initiation and throughout the procedure, even in patients with poor systolic function. CONCLUSION: This noninvasive TH procedure seems efficient and safe in all patients remaining comatose after CA. Thanks to its simplicity, it could allow prehospital cooling to reach the target temperature more rapidly.

Feasibility study on full closed-loop control ventilation (IntelliVent-ASV™) in ICU patients with acute respiratory failure: a prospective observational comparative study.

INTRODUCTION: IntelliVent-ASV™ is a full closed-loop ventilation mode that automatically adjusts ventilation and oxygenation parameters in both passive and active patients. This feasibility study compared oxygenation and ventilation settings automatically selected by IntelliVent-ASV™ among three predefined lung conditions (normal lung, acute respiratory distress syndrome (ARDS) and chronic obstructive pulmonary disease (COPD)) in active and passive patients. The feasibility of IntelliVent-ASV™ use was assessed based on the number of safety events, the need to switch to conventional mode for any medical reason, and sensor failure. METHOD: This prospective observational comparative study included 100 consecutive patients who were invasively ventilated for less than 24 hours at the time of inclusion with an expected duration of ventilation of more than 12 hours. Patients were ventilated using IntelliVent-ASV™ from inclusion to extubation. Settings, automatically selected by the ventilator, delivered ventilation, respiratory mechanics, and gas exchanges were recorded once a day. RESULTS: Regarding feasibility, all patients were ventilated using IntelliVent-ASV™ (392 days in total). No safety issues occurred and there was never a need to switch to an alternative ventilation mode. The fully automated ventilation was used for 95% of the total ventilation time. IntelliVent-ASV™ selected different settings according to lung condition in passive and active patients. In passive patients, tidal volume (VT), predicted body weight (PBW) was significantly different between normal lung (n = 45), ARDS (n = 16) and COPD patients (n = 19) (8.1 (7.3 to 8.9) mL/kg; 7.5 (6.9 to 7.9) mL/kg; 9.9 (8.3 to 11.1) mL/kg, respectively; P 0.05). In passive ARDS patients, FiO2 and positive end-expiratory pressure (PEEP) were statistically higher than passive normal lung (35 (33 to 47)% versus 30 (30 to 31)% and 11 (8 to 13) cmH2O versus 5 (5 to 6) cmH2O, respectively; P< 0.05). CONCLUSIONS: IntelliVent-ASV™ was safely used in unselected ventilated ICU patients with different lung conditions. Automatically selected oxygenation and ventilation settings were different according to the lung condition, especially in passive patients. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01489085.

Safety and efficacy of a fully closed-loop control ventilation (IntelliVent-ASV®) in sedated ICU patients with acute respiratory failure: a prospective randomized crossover study.

PURPOSE: IntelliVent-ASV(®) is a development of adaptive support ventilation (ASV) that automatically adjusts ventilation and oxygenation parameters. This study assessed the safety and efficacy of IntelliVent-ASV(®) in sedated intensive care unit (ICU) patients with acute respiratory failure. METHODS: This prospective randomized crossover comparative study was conducted in a 12-bed ICU in a general hospital. Two periods of 2 h of ventilation in randomly applied ASV or IntelliVent-ASV(®) were compared in 50 sedated, passively ventilated patients. Tidal volume (V(T)), respiratory rate (RR), inspiratory pressure (P(INSP)), SpO(2) and E(T)CO(2) were continuously monitored and recorded breath by breath. Mean values over the 2-h period were calculated. Respiratory mechanics, plateau pressure (P(PLAT)) and blood gas exchanges were measured at the end of each period. RESULTS: There was no safety issue requiring premature interruption of IntelliVent-ASV(®). Minute ventilation (MV) and V(T) decreased from 7.6 (6.5-9.5) to 6.8 (6.0-8.0) L/min (p < 0.001) and from 8.3 (7.8-9.0) to 8.1 (7.7-8.6) mL/kg PBW (p = 0.003) during IntelliVent-ASV(®) as compared to ASV. P(PLAT) and FiO(2) decreased from 24 (20-29) to 20 (19-25) cmH(2)O (p = 0.005) and from 40 (30-50) to 30 (30-39) % (p < 0.001) during IntelliVent-ASV(®) as compared to ASV. RR, P(INSP), and PEEP decreased as well during IntelliVent-ASV(®) as compared to ASV. Respiratory mechanics, pH, PaO(2) and PaO(2)/FiO(2) ratio were not different but PaCO(2) was slightly higher during IntelliVent-ASV(®) as compared to ASV. CONCLUSIONS: In passive patients with acute respiratory failure, IntelliVent-ASV(®) was safe and able to ventilate patients with less pressure, volume and FiO(2) while producing the same results in terms of oxygenation.

Optimal duration of a sustained inflation recruitment maneuver in ARDS patients.

PURPOSE: To measure the dynamics of recruitment and the hemodynamic status during a sustained inflation recruitment maneuver (RM) in order to determine the optimal duration of RM in acute respiratory distress syndrome (ARDS) patients. METHODS: This prospective study was conducted in a 12-bed intensive care unit (ICU) in a general hospital. A 40 cmH(2)O sustained inflation RM maintained for 30 s was performed in 50 sedated ventilated patients within the first 24 h of meeting ARDS criteria. Invasive arterial pressures, heart rate, and SpO(2) were measured at 10-s intervals during the RM. The volume increase during the RM was measured by integration of the flow required to maintain the pressure at 40 cmH(2)O, which provides an estimation of the volume recruited during the RM. Raw data were corrected for gas consumption and fitted with an exponential curve in order to determine an individual time constant for the volume increase. RESULTS: The average volume increase and time constant were 210 ± 198 mL and 2.3 ± 1.3 s, respectively. Heart rate, diastolic arterial pressure, and SpO(2) did not change during or after the RM. Systolic and mean arterial pressures were maintained at 10 s, decreased significantly at 20 and 30 s during the RM, and recovered to the pre-RM value 30 s after the end of the RM (ANOVA, p < 0.01). CONCLUSIONS: In early-onset ARDS patients, most of the recruitment occurs during the first 10 s of a sustained inflation RM. However, hemodynamic impairment is significant after the tenth second of RM.

Recruitability of the lung estimated by the pressure volume curve hysteresis in ARDS patients.

OBJECTIVE: To assess the hysteresis of the pressure-volume curve (PV curve) as to estimate, easily and at the bedside, the recruitability of the lung in ARDS patients. DESIGN: Prospective study. SETTING: Twelve medico-surgical ICU beds of a general hospital. PATIENTS: Twenty-six patients within the first 24 h from meeting ARDS criteria. INTERVENTION: A Quasi-static inflation and deflation PV curve from 0 to 40 cmH(2)O and a 40 cmH(2)O recruitment maneuver (RM) maintained for 10 s were successively done with an interval of 30 min in between. RECORDINGS AND CALCULATION: Hysteresis of the PV curve (H(PV)) was calculated as the ratio of the area enclosed by the pressure volume loop divided by the predicted body weight (PBW). The volume increase during the RM (V(RM)) was measured by integration of the flow required to maintain the pressure at 40 cmH(2)O and divided by PBW, as an estimation of the volume recruited during the RM. RESULTS: A positive linear correlation was found between H(PV) and V(RM) (r = 0.81, P < 0.0001). CONCLUSIONS: The results suggest using the hysteresis of the PV curve to assess the recruitability of the lung.

Role of open-lung biopsy in acute respiratory distress syndrome.

PURPOSE OF REVIEW: When classic examinations such as bronchoalveolar lavage are not contributory in the etiologic diagnosis of unresolving acute respiratory distress syndrome, surgical lung biopsy would appear to be useful to determine the specific cause, particularly infection or postaggressive fibrosis, which could benefit from an adapted treatment. RECENT FINDINGS: Postaggressive pulmonary fibrosis is a possible evolution for unresolving acute respiratory distress syndrome and its association with a poor prognosis has been demonstrated. The administration of corticoids would make it possible to improve certain ventilatory parameters as well as the prognosis in the fibroproliferation stage. No clinical or usual microbiological criterion can confirm both the existence of fibrosis and nosocomial pneumonia. Biological markers for fibrosis such as procollagen III are not validated to confirm the appearance of a postaggressive fibrosis. A recent study has shown that surgical lung biopsy performed in patients with unresolving acute respiratory distress syndrome led to a therapeutic modification in 78% of the cases and made it possible to avoid empiric corticotherapy in nearly 50% of the cases considering the absence of fibrosis. SUMMARY: Surgical lung biopsy could be proposed for patients with unresolving acute respiratory distress syndrome after 7-10 days of evolution despite well-conducted initial treatment when the etiology of acute respiratory distress syndrome has not been confirmed or when the appearance of postaggressive fibrosis is suspected.

Automatic selection of breathing pattern using adaptive support ventilation.

OBJECTIVE: In a cohort of mechanically ventilated patients to compare the automatic tidal volume (VT)-respiratory rate (RR) combination generated by adaptive support ventilation (ASV) for various lung conditions. DESIGN AND SETTING: Prospective observational cohort study in the 11-bed medicosurgical ICU of a general hospital. PATIENTS: 243 patients receiving 1327 days of invasive ventilation on ASV. MEASUREMENTS: Daily collection of ventilator settings, breathing pattern, arterial blood gases, and underlying clinical respiratory conditions categorized as: normal lungs, ALI/ARDS, COPD, chest wall stiffness, or acute respiratory failure. RESULTS: Overall the respiratory mechanics differed significantly with the underlying conditions. In passive patients ASV delivered different VT-RR combinations based on the underlying condition, providing higher VT and lower RR in COPD than in ALI/ARDS: 9.3ml/kg (8.2-10.8) predicted body weight (PBW) and 13 breaths/min (11-16) vs. 7.6ml/kg (6.7-8.8) PBW and 18 breaths/min (16-22). In patients actively triggering the ventilator the VT-RR combinations did not differ between COPD, ALI/ARDS, and normal lungs. CONCLUSIONS: ASV selects different VT-RR combinations based on respiratory mechanics in passive, mechanically ventilated patients.

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.

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.

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.

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.

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.