Pierre-Alexandre Bouchard

Automated oxygen titration and weaning with FreeO 2 in patients with acute exacerbation of COPD: a pilot randomized trial

Introduction We developed a device (FreeO2) that automatically adjusts the oxygen flow rates based on patients’ needs, in order to limit hyperoxia and hypoxemia and to automatically wean them from oxygen. Objective The aim of this study was to evaluate the feasibility of using FreeO2 in patients hospitalized in the respiratory ward for an acute exacerbation of COPD. Methods We conducted a randomized controlled trial comparing FreeO2 vs manual oxygen titration in the respiratory ward of a university hospital. We measured the perception of appropriateness of oxygen titration and monitoring in both groups by nurses and attending physicians using a Likert scale. We evaluated the time in the target range of oxygen saturation (SpO2) as defined for each patient by the attending physician, the time with severe desaturation (SpO2 <85%), and the time with hyperoxia (SpO2 >5% above the target). We also recorded length of stay, intensive care unit admissions, and readmission rate. Fifty patients were randomized (25 patients in both groups; mean age: 72±8 years; mean forced expiratory volume in 1 second: 1.00±0.49 L; and mean initial O2 flow 2.0±1.0 L/min). Results Nurses and attending physicians felt that oxygen titration and monitoring were equally appropriate with both O2 administration systems. The percentage of time within the SpO2 target was significantly higher with FreeO2, and the time with severe desaturation and hyperoxia was significantly reduced with FreeO2. Time from study inclusion to hospital discharge was 5.8±4.4 days with FreeO2 and 8.4±6.0 days with usual oxygen administration (P=0.051). Conclusion FreeO2 was deemed as an appropriate oxygen administration system by nurses and physicians of a respiratory unit. This system maintained SpO2 at the target level better than did manual titration and reduced periods of desaturation and hyperoxia. Our results also suggest that FreeO2 has the potential to reduce the hospital length of stay.

Comparison of usual and alternative methods to measure height in mechanically ventilated patients: potential impact on protective ventilation

BACKGROUND: Protective ventilation implementation requires the calculation of predicted body weight (PBW), determined by a formula based on gender and height. Consequently, height inaccuracy may be a limiting factor to correctly set tidal volumes. The objective of this study was to evaluate the accuracy of different methods in measuring heights in mechanically ventilated patients. METHODS: Before cardiac surgery, actual height was measured with a height gauge while subjects were standing upright (reference method); the height was also estimated by alternative methods based on lower leg and forearm measurements. After cardiac surgery, upon ICU admission, a subjects height was visually estimated by a clinician and then measured with a tape measure while the subject was supine and undergoing mechanical ventilation. RESULTS: One hundred subjects (75 men, 25 women) were prospectively included. Mean PBW was 61.0 ± 9.7 kg, and mean actual weight was 30.3% higher. In comparison with the reference method, estimating the height visually and using the tape measure were less accurate than both lower leg and forearm measurements. Errors above 10% in calculating the PBW were present in 25 and 40 subjects when the tape measure or visual estimation of height was used in the formula, respectively. With lower leg and forearm measurements, 15 subjects had errors above 10% (P < .001). CONCLUSIONS: Our results demonstrate that significant variability exists between the different methods used to measure height in bedridden patients on mechanical ventilation. Alternative methods based on lower leg and forearm measurements are potentially interesting solutions to facilitate the accurate application of protective ventilation.

Effects of High-flow Nasal Cannula on the Work of Breathing in Patients Recovering From Acute Respiratory Failure*

Objectives: High-flow nasal cannula is increasingly used in the management of respiratory failure. However, little is known about its impact on respiratory effort, which could explain part of the benefits in terms of comfort and efficiency. This study was designed to assess the effects of high-flow nasal cannula on indexes of respiratory effort (i.e., esophageal pressure variations, esophageal pressure-time product/min, and work of breathing/min) in adults. Design: A randomized controlled crossover study was conducted in 12 patients with moderate respiratory distress (i.e., after partial recovery from an acute episode, allowing physiologic measurements). Setting: Institut Universitaire de Cardiologie et de Pneumologie de Québec, QC, Canada. Subjects: Twelve adult patients with respiratory distress symptoms were enrolled in this study. Interventions: Four experimental conditions were evaluated: baseline with conventional oxygen therapy and high-flow nasal cannula at 20, 40, and 60 L/min. The primary outcomes were the indexes of respiratory effort (i.e., esophageal pressure variations, esophageal pressure-time product/min, and work of breathing/min). Secondary outcomes included tidal volume, respiratory rate, minute volume, dynamic lung compliance, inspiratory resistance, and blood gases. Measurements and Main Results: Esophageal pressure variations decreased from 9.8 (5.8–14.6) cm H2O at baseline to 4.9 (2.1–9.1) cm H2O at 60 L/min (p = 0.035). Esophageal pressure-time product/min decreased from 165 (126–179) to 72 (54–137) cm H2O • s/min, respectively (p = 0.033). Work of breathing/min decreased from 4.3 (3.5–6.3) to 2.1 (1.5–5.0) J/min, respectively (p = 0.031). Respiratory pattern variables and capillary blood gases were not significantly modified between experimental conditions. Dynamic lung compliance increased from 38 (24–64) mL/cm H2O at baseline to 59 (43–175) mL/cm H2O at 60 L/min (p = 0.007), and inspiratory resistance decreased from 9.6 (5.5–13.4) to 5.0 (1.0–9.1) cm H2O/L/s, respectively (p = 0.07). Conclusions: High-flow nasal cannula, when set at 60 L/min, significantly reduces the indexes of respiratory effort in adult patients recovering from acute respiratory failure. This effect is associated with an improvement in respiratory mechanics.

Automatic Oxygen Titration During Walking in Subjects With COPD: A Randomized Crossover Controlled Study.

BACKGROUND: Arterial oxygen desaturation frequently occurs in patients with COPD during daily activities at home. Oxygen flow is usually set at fixed and low rates for ambulatory patients. We evaluated an innovative closed-loop system (FreeO2) that automatically adjusts the oxygen flow to the patients needs in subjects with COPD during walking followed by recovery time, such as during ambulatory conditions. METHODS: Patients with COPD who exhibited oxygen desaturation on exertion were included in the study. Subjects performed endurance shuttle walk tests followed by 10 min of recovery. The tests were conducted in a random order and in crossover with the 3 following conditions: subjects breathing (1) air at 2 L/min, (2) oxygen at 2 L/min, or (3) FreeO2 (variable oxygen flow). SpO2, pulse rate, PETCO2, breathing frequency, and oxygen flow were continuously recorded during the 3 conditions. The primary outcome was the percentage of time within the SpO2 target of 92–96%. Secondary outcomes included the endurance shuttle walk test time and distance. RESULTS: Sixteen subjects with COPD were recruited. The percentage of time with SpO2 in the target range (92–96%) was higher while using the FreeO2, and time with severe oxygen desaturation (SpO2 <88%) was lower with FreeO2 in comparison with constant-flow oxygen and air testing conditions (0.6% vs 23.9% vs 52.2%, P < .001). In comparison with air, walking distance was increased by 35% with oxygen (P = .045) and by 63% with FreeO2 (P < .001). The walking distance was increased by 17% with FreeO2 in comparison with constant oxygen, but the difference was not statistically significant (P = .22). CONCLUSIONS: Automatic titration of oxygen flow during walking to maintain oxygen saturation in a specified range improves oxygenation and may improve exercise tolerance during daily activity, such as walking, in patients with COPD in comparison with room air and fixed oxygen administration. (ClinicalTrials.gov registration: NCT02150434.)

Automatic versus manual oxygen administration in the emergency department

Oxygen is commonly administered in hospitals, with poor adherence to treatment recommendations. We conducted a multicentre randomised controlled study in patients admitted to the emergency department requiring O2 ≥3 L·min−1. Patients were randomised to automated closed-loop or manual O2 titration during 3 h. Patients were stratified according to arterial carbon dioxide tension (PaCO2) (hypoxaemic PaCO2≤45 mmHg; or hypercapnic PaCO2>45–≤55 mmHg) and study centre. Arterial oxygen saturation measured by pulse oximetry (SpO2) goals were 92–96% for hypoxaemic, or 88–92% for hypercapnic patients. Primary outcome was % time within SpO2 target. Secondary endpoints were hypoxaemia and hyperoxia prevalence, O2 weaning, O2 duration and hospital length of stay. 187 patients were randomised (93 automated, 94 manual) and baseline characteristics were similar between the groups. Time within the SpO2 target was higher under automated titration (81±21% versus 51±30%, p<0.001). Time with hypoxaemia (3±9% versus 5±12%, p=0.04) and hyperoxia under O2 (4±9% versus 22±30%, p<0.001) were lower with automated titration. O2 could be weaned at the end of the study in 14.1% versus 4.3% patients in the automated and manual titration group, respectively (p<0.001). O2 duration during the hospital stay was significantly reduced (5.6±5.4 versus 7.1±6.3 days, p=0.002). Automated O2 titration in the emergency department improved oxygenation parameters and adherence to guidelines, with potential clinical benefits. Automated oxygen titration is superior to manual administration in terms of time within oxygenation targets http://ow.ly/pgWC30c2sLv

Cost-effectiveness of FreeO2 in patients with chronic obstructive pulmonary disease hospitalised for acute exacerbations: analysis of a pilot study in Quebec

Objective Conduct a cost-effectiveness analysis of FreeO2 technology versus manual oxygen-titration technology for patients with chronic obstructive pulmonary disease (COPD) hospitalised for acute exacerbations. Setting Tertiary acute care hospital in Quebec, Canada. Participants 47 patients with COPD hospitalised for acute exacerbations. Intervention An automated oxygen-titration and oxygen-weaning technology. Methods and outcomes The costs for hospitalisation and follow-up for 180 days were calculated using a microcosting approach and included the cost of FreeO2 technology. Incremental cost-effectiveness ratios (ICERs) were calculated using bootstrap resampling with 5000 replications. The main effect variable was the percentage of time spent at the target oxygen saturation (SpO2). The other two effect variables were the time spent in hyperoxia (target SpO2+5%) and in severe hypoxaemia (SpO2 <85%). The resamplings were based on data from a randomised controlled trial with 47 patients with COPD hospitalised for acute exacerbations. Results FreeO2 generated savings of 20.7% of the per-patient costs at 180 days (ie, −

Impact of Gas Masks on Work of Breathing, Breathing Patterns, and Gas Exchange in Healthy Subjects

C2959.71). This decrease is nevertheless not significant at the 95% threshold (P=0.13), but the effect variables all improved (P<0.001). The improvement in the time spent at the target SpO2 was 56.3%. The ICERs indicate that FreeO2 technology is more cost-effective than manual oxygen titration with a savings of −

Evaluation of fully automated ventilation: a randomized controlled study in post-cardiac surgery patients

C96.91 per percentage point of time spent at the target SpO2 (95% CI −301.26 to 116.96). Conclusion FreeO2 technology could significantly enhance the efficiency of the health system by reducing per-patient costs at 180 days. A study with a larger patient sample needs to be carried out to confirm these preliminary results. Trial registration number NCT01393015; Post-results.

Prospective Randomized Controlled Study Comparing Conventional Ventilation Versus A Fully Closed-loop Ventilation (IntelliVent®) In Post Cardiac Surgery ICU Patients

BACKGROUND: The gas mask is used to protect military and non-military personnel exposed to respiratory hazards (chemical, biologic, radiologic, and nuclear agents). The objective was to evaluate the impact of the gas mask on indexes of respiratory effort and breathing patterns in a human model because no data exist. METHODS: The design of the study was a crossover evaluation with four 10-min conditions in a randomized order: with and without wearing the gas mask when at rest and when exerting a standardized effort. During the studied conditions, 14 healthy subjects were evaluated for breathing patterns, indexes of respiratory effort (work of breathing, pressure-time product for esophageal pressure, and esophageal pressure swing) and capillary blood gases. Continuous SpO2 was recorded during the tested conditions. RESULTS: The indexes of respiratory effort significantly increased when subjects wore the gas mask under the tested conditions (at rest and during effort). The work of breathing was significantly augmented with the mask (at rest, 0.40 ± 0.32 J/cycle vs 0.25 ± 0.10 J/cycle; effort, 5.96 ± 3.32 J/cycle vs 4.43 ± 2.50 J/cycle; P < .001). The other indexes of effort (esophageal pressure-time product and esophageal swing were all significantly increased, from 30 to 60%, with a gas mask in comparison with at baseline without a gas mask). The impact on breathing patterns and PaCO2 was limited, without significant differences. Moderate hypoxemia was present during effort and was not increased by the gas mask. CONCLUSIONS: This study demonstrated a substantial increase in the indicies of respiratory effort both at rest and during exercise with a gas mask. Our measurements and findings may be referred in future research and development studies in this field. (ClinicalTrials.gov registration NCT02782936.)