Comparison of high-flow nasal therapy, noninvasive ventilation, and continuous positive airway pressure on outcomes in critically ill patients admitted for COVID-19 with acute respiratory failure.

BACKGROUND: The optimal first-line noninvasive respiratory support (NIRS) to improve outcome in patients affected by COVID-19 pneumonia admitted to ICU is still debated. METHODS: We conducted a retrospective study in seven French ICUs, including all adults admitted between July and December 2020 with documented SARS-CoV-2 acute respiratory failure (PaO2/FiO2<300 mmHg), and treated with either high-flow nasal therapy (HFNT) alone, noninvasive ventilation alone or in combination with HFNT (NIV), or continuous positive airway pressure alone or in combination with HFNT (CPAP). The primary outcome was NIRS failure at day 28, defined as the need for endotracheal intubation (ETI) or death without ETI. RESULTS: Among the 355 patients included, 160 (45%) were treated with HFNT alone, 115 (32%) with NIV and 80 (23%) with CPAP. The primary outcome occurred in 65 (41%), 69 (60%), and 25 (31%) patients among those treated with HFNT alone, NIV, and CPAP, respectively (P<0.001). After univariate analysis, patients treated with CPAP had a trend for a lower incidence of the primary outcome, whereas patients treated with NIV had a significant higher incidence of the primary outcome, both compared to those treated with HFNT alone (unadjusted Hazard ratio 0.67; 95% CI [0.42-1.06], and 1.58; 95% CI [1.12-2.22]; P=0.09 and 0.008, respectively). CONCLUSIONS: Among ICU patients admitted for severe COVID-19 pneumonia and managed with NIRS, the outcome seems to differ according to the initial chosen strategy. Prospective randomized controlled studies are warranted to identify the optimal strategy.

Airway and transpulmonary driving pressures and mechanical powers selected by INTELLiVENT-ASV in passive, mechanically ventilated ICU patients.

BACKGROUND: Driving pressure (ΔP) and mechanical power (MP) are predictors of the risk of ventilation- induced lung injuries (VILI) in mechanically ventilated patients. INTELLiVENT-ASV® is a closed-loop ventilation mode that automatically adjusts respiratory rate and tidal volume, according to the patient's respiratory mechanics. OBJECTIVES: This prospective observational study investigated ΔP and MP (and also transpulmonary ΔP (ΔPL) and MP (MPL) for a subgroup of patients) delivered by INTELLiVENT-ASV. METHODS: Adult patients admitted to the ICU were included if they were sedated and met the criteria for a single lung condition (normal lungs, COPD, or ARDS). INTELLiVENT-ASV was used with default target settings. If PEEP was above 16 cmH2O, the recruitment strategy used transpulmonary pressure as a reference, and ΔPL and MPL were computed. Measurements were made once for each patient. RESULTS: Of the 255 patients included, 98 patients were classified as normal-lungs, 28 as COPD, and 129 as ARDS patients. The median ΔP was 8 (7 - 10), 10 (8 - 12), and 9 (8 - 11) cmH2O for normal-lungs, COPD, and ARDS patients, respectively. The median MP was 9.1 (4.9 - 13.5), 11.8 (8.6 - 16.5), and 8.8 (5.6 - 13.8) J/min for normal-lungs, COPD, and ARDS patients, respectively. For the 19 patients managed with transpulmonary pressure ΔPL was 6 (4 - 7) cmH2O and MPL was 3.6 (3.1 - 4.4) J/min. CONCLUSIONS: In this short term observation study, INTELLiVENT-ASV selected ΔP and MP considered in safe ranges for lung protection. In a subgroup of ARDS patients, the combination of a recruitment strategy and INTELLiVENT-ASV resulted in an apparently safe ΔPL and MPL.

Setting up home noninvasive ventilation.

Home noninvasive ventilation (NIV) is widely used to correct nocturnal alveolar hypoventilation in patients with chronic respiratory failure of various etiologies. The most commonly used ventilation mode is pressure support with a backup respiratory rate. This mode requires six main settings, as well as some additional settings that should be adjusted according to the individual patient. This review details the effect of each setting, how the settings should be adjusted according to each patient, and the risks if they are not adjusted correctly. The examples described here are based on real patient cases and bench simulations. Optimizing the settings for home NIV may improve the quality and tolerance of the treatment.

Parameters for Simulation of Adult Subjects During Mechanical Ventilation.

BACKGROUND: Simulation studies are often used to examine ventilator performance. However, there are no standards for selecting simulation parameters. This study collected data in passively-ventilated adult human subjects and summarized the results as a set of parameters that can be used for simulation studies of intubated, passive, adult subjects with normal lungs, COPD, or ARDS. METHODS: Consecutive adult patients admitted to the ICU were included if they were deeply sedated and mechanically ventilated for <48 h without any spontaneous breathing activity. Subjects were classified as having normal lungs, COPD, or ARDS. Respiratory mechanics variables were collected once per subject. Static compliance was calculated as the ratio between tidal volume and driving pressure. Inspiratory resistance was measured by the least-squares fitting method. The expiratory time constant was estimated by the tidal volume/flow ratio. RESULTS: Of the 359 subjects included, 138 were classified as having normal lungs, 181 as ARDS, and 40 as COPD. Median (interquartile range) static compliance was significantly lower in ARDS subjects as compared with normal lung and COPD subjects (39 [32-50] mL/cm H2O vs 54 [44-64] and 59 [43-75] mL/cm H2O, respectively, P < .001). Inspiratory resistance was significantly higher in COPD subjects as compared with normal lung and ARDS subjects (22 [16-33] cm H2O/L/s vs 13 [10-15] and 12 [9-14] cm H2O/L/s, respectively, P < .001). The expiratory time constant was significantly different for each lung condition (0.60 [0.51-0.71], 1.07 [0.68-2.14], and 0.46 [0.40-0.55] s for normal lung, COPD, and ARDS subjects, respectively, P < .001). In the subgroup of subjects with ARDS, there were no significant differences in respiratory mechanics variables among mild, moderate, and severe ARDS. CONCLUSIONS: This study provides educators, researchers, and manufacturers with a standard set of practical parameters for simulating the respiratory system's mechanical properties in passive conditions.

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.

Practical Insight to Monitor Home NIV in COPD Patients.

Home noninvasive ventilation (NIV) is used in COPD patients with concomitant chronic hypercapnic respiratory failure in order to correct nocturnal hypoventilation and improve sleep quality, quality of life, and survival. Monitoring of home NIV is needed to assess the effectiveness of ventilation and adherence to therapy, resolve potential adverse effects, reinforce patient knowledge, provide maintenance of the equipment, and readjust the ventilator settings according to the changing condition of the patient. Clinical monitoring is very informative. Anamnesis focuses on the improvement of nocturnal hypoventilation symptoms, sleep quality, and side effects of NIV. Side effects are major cause of intolerance. Screening side effects leads to modification of interface, gas humidification, or ventilator settings. Home care providers maintain ventilator and interface and educate patients for correct use. However, patient's education should be supervised by specialized clinicians. Blood gas measurement shows a significant decrease in PaCO2 when NIV is efficient. Analysis of ventilator data is very useful to assess daily use, unintentional leaks, upper airway obstruction, and patient ventilator synchrony. Nocturnal oximetry and capnography are additional monitoring tools to assess the impact of NIV on gas exchanges. In the near future, telemonitoring will reinforce and change the organization of home NIV for COPD patients.

A Multicenter Randomized Trial Assessing the Efficacy of Helium/Oxygen in Severe Exacerbations of Chronic Obstructive Pulmonary Disease.

RATIONALE: During noninvasive ventilation (NIV) for chronic obstructive pulmonary disease (COPD) exacerbations, helium/oxygen (heliox) reduces the work of breathing and hypercapnia more than air/O2, but its impact on clinical outcomes remains unknown. OBJECTIVES: To determine whether continuous administration of heliox for 72 hours, during and in-between NIV sessions, was superior to air/O2 in reducing NIV failure (25-15%) in severe hypercapnic COPD exacerbations. METHODS: This was a prospective, randomized, open-label trial in 16 intensive care units (ICUs) and 6 countries. Inclusion criteria were COPD exacerbations with PaCO2 ≥ 45 mm Hg, pH ≤ 7.35, and at least one of the following: respiratory rate ≥ 25/min, PaO2 ≤ 50 mm Hg, and oxygen saturation (arterial [SaO2] or measured by pulse oximetry [SpO2]) ≤ 90%. A 6-month follow-up was performed. MEASUREMENTS AND MAIN RESULTS: The primary endpoint was NIV failure (intubation or death without intubation in the ICU). The secondary endpoints were physiological parameters, duration of ventilation, duration of ICU and hospital stay, 6-month recurrence, and rehospitalization rates. The trial was stopped prematurely (445 randomized patients) because of a low global failure rate (NIV failure: air/O2 14.5% [n = 32]; heliox 14.7% [n = 33]; P = 0.97, and time to NIV failure: heliox group 93 hours [n = 33], air/O2 group 52 hours [n = 32]; P = 0.12). Respiratory rate, pH, PaCO2, and encephalopathy score improved significantly faster with heliox. ICU stay was comparable between the groups. In patients intubated after NIV failed, patients on heliox had a shorter ventilation duration (7.4 ± 7.6 d vs. 13.6 ± 12.6 d; P = 0.02) and a shorter ICU stay (15.8 ± 10.9 d vs. 26.7 ± 21.0 d; P = 0.01). No difference was observed in ICU and 6-month mortality. CONCLUSIONS: Heliox improves respiratory acidosis, encephalopathy, and the respiratory rate more quickly than air/O2 but does not prevent NIV failure. Overall, the rate of NIV failure was low. Clinical trial registered with www.clinicaltrials.gov (NCT 01155310).

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.

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.