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.

Dynamics of end expiratory lung volume after changing positive end-expiratory pressure in acute respiratory distress syndrome patients.

INTRODUCTION: Lung recruitment maneuvers followed by an individually titrated positive end-expiratory pressure (PEEP) are the key components of the open lung ventilation strategy in acute respiratory distress syndrome (ARDS). The staircase recruitment maneuver is a step-by-step increase in PEEP followed by a decremental PEEP trial. The duration of each step is usually 2 minutes without physiologic rationale. METHODS: In this prospective study, we measured the dynamic end-expiratory lung volume changes (ΔEELV) during an increase and decrease in PEEP to determine the optimal duration for each step. PEEP was progressively increased from 5 to 40 cmH2O and then decreased from 40 to 5 cmH2O in steps of 5 cmH2O every 2.5 minutes. The dynamic of ΔEELV was measured by direct spirometry as the difference between inspiratory and expiratory tidal volumes over 2.5 minutes following each increase and decrease in PEEP. ΔEELV was separated between the expected increased volume, calculated as the product of the respiratory system compliance by the change in PEEP, and the additional volume. RESULTS: Twenty-six early onset moderate or severe ARDS patients were included. Data are expressed as median [25th-75th quartiles]. During the increase in PEEP, the expected increased volume was achieved within 2[2-2] breaths. During the decrease in PEEP, the expected decreased volume was achieved within 1 [1-1] breath, and 95 % of the additional decreased volume was achieved within 8 [2-15] breaths. Completion of volume changes in 99 % of both increase and decrease in PEEP events required 29 breaths. CONCLUSIONS: In early ARDS, most of the ΔEELV occurs within the first minute, and change is completed within 2 minutes, following an increase or decrease in PEEP.

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.

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.

A risk score-dependent antiemetic approach effectively reduces postoperative nausea and vomiting--a continuous quality improvement initiative.

PURPOSE: In a previous survey, patients at risk for postoperative nausea and vomiting (PONV) were best identified by a simplified risk score. Consequently, we investigated whether a risk score-dependent antiemetic strategy could effectively reduce the incidence of PONV in our department. METHODS: Adult in-patients (n = 428) scheduled for throat, thyroid, breast or gynecological surgery under general anesthesia were prospectively classified in three risk groups (L = low, M = medium, H = high) by using a simplified risk score. Patients in the L group did not receive any antiemetic prophylaxis. Patients in the M group received volatile anesthesia with 0.625 mg droperidol or an iv propofol anesthesia without droperidol. Patients in the H group received iv anesthesia supplemented with 4 mg dexamethasone and 0.625 mg droperidol. RESULTS: Compared with the data from our previous survey, the overall incidence of PONV decreased from 49.5% to 14.3% (P < 0.001). The incidence decreased from 34% to 13.2% (P < 0.001) in the M group and from 64.3% to 15.5% (P < 0.001) in the H group. Mean postanesthesia care unit time decreased from 99 to 82 min (P < 0.04). CONCLUSION: This is the first survey which suggests that the departmental incidence of PONV can be significantly lowered by a risk score-dependent antiemetic strategy through a quality improvement initiative.