Effect of Ward-Based High-Flow Nasal Cannula (HFNC) Oxygen Therapy on Critical Care Utilization During the COVID-19 Pandemic: A Retrospective Cohort Analysis.

BACKGROUND: Hospitals expanded critical care capacity during the COVID-19 pandemic by treating COVID-19 patients with high-flow nasal cannula oxygen therapy (HFNC) in non-traditional settings, including general internal medicine (GIM) wards. The impact of this practice on intensive care unit (ICU) capacity is unknown. OBJECTIVE: To describe how our hospital operationalized the use of HFNC on GIM wards, assess its impact on ICU capacity, and examine the characteristics and outcomes of treated patients. DESIGN: Retrospective cohort study of all patients treated with HFNC on GIM wards at a Canadian tertiary care hospital. PARTICIPANTS: All patients admitted with COVID-19 and treated with HFNC on GIM wards from December 28, 2020, to June 13, 2021, were included. MAIN MEASURES: We combined administrative data on critical care occupancy daily with chart-abstracted data for included patients to establish the total number of patients receiving ICU-level care at our hospital per day. We also collected data on demographics, medical comorbidities, illness severity, COVID-19 treatments, HFNC care processes, and patient outcomes. KEY RESULTS: We treated 124 patients with HFNC on the GIM wards (median age 66 years; 48% female). Patients were treated with HFNC for a median of 5 days (IQR 3 to 8); collectively, they received HFNC for a total of 740 hospital days, 71% of which were on GIM wards. At peak ICU capacity strain (144%), delivering HFNC on GIM wards added 20% to overall ICU capacity by managing up to 14 patients per day. Patients required a median maximal fraction of inspired oxygen of 80% (IQR 60 to 95). There were 18 deaths (15%) and 85 patients (69%) required critical care admission; of those, 40 (47%) required mechanical ventilation. CONCLUSIONS: With appropriate training and resources, treatment of COVID-19 patients with HFNC on GIM wards appears to be a feasible strategy to increase critical care capacity.

Quantitative Assessment of Viral Dispersion Associated with Respiratory Support Devices in a Simulated Critical Care Environment.

Rationale: Patients with severe coronavirus disease (COVID-19) require supplemental oxygen and ventilatory support. It is unclear whether some respiratory support devices may increase the dispersion of infectious bioaerosols and thereby place healthcare workers at increased risk of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).Objectives: To quantitatively compare viral dispersion from invasive and noninvasive respiratory support modalities.Methods: This study used a simulated ICU room with a breathing-patient simulator exhaling nebulized bacteriophages from the lower respiratory tract with various respiratory support modalities: invasive ventilation (through an endotracheal tube with an inflated cuff connected to a mechanical ventilator), helmet ventilation with a positive end-expiratory pressure (PEEP) valve, noninvasive bilevel positive-pressure ventilation, nonrebreather face masks, high-flow nasal oxygen (HFNO), and nasal prongs.Measurements and Main Results: Invasive ventilation and helmet ventilation with a PEEP valve were associated with the lowest bacteriophage concentrations in the air, and HFNO and nasal prongs were associated with the highest concentrations. At the intubating position, bacteriophage concentrations associated with HFNO (2.66 × 104 plaque-forming units [PFU]/L of air sampled), nasal prongs (1.60 × 104 PFU/L of air sampled), nonrebreather face masks (7.87 × 102 PFU/L of air sampled), and bilevel positive airway pressure (1.91 × 102 PFU/L of air sampled) were significantly higher than those associated with invasive ventilation (P < 0.05 for each). The difference between bacteriophage concentrations associated with helmet ventilation with a PEEP valve (4.29 × 10-1 PFU/L of air sampled) and bacteriophage concentrations associated with invasive ventilation was not statistically significant.Conclusions: These findings highlight the potential differential risk of dispersing virus among respiratory support devices and the importance of appropriate infection prevention and control practices and personal protective equipment for healthcare workers when caring for patients with transmissible respiratory viral infections such as SARS-CoV-2.

Home monitoring of daytime mouthpiece ventilation effectiveness in patients with neuromuscular disease.

Mouthpiece ventilation (MPV) allows patients with neuromuscular disease to receive daytime support from a portable ventilator, which they can disconnect at will, for example, for speaking, eating, swallowing, and coughing. However, MPV carries a risk of underventilation. Our purpose here was to evaluate the effectiveness of daytime MPV under real-life conditions. Eight wheelchair-bound patients who used MPV underwent daytime polygraphy at home with recordings of airflow, mouthpiece pressure, thoracic and abdominal movements, peripheral capillary oxygen saturation (SpO2), and transcutaneous partial pressure of carbon dioxide (PtcCO2). Times and durations of tasks and activities were recorded. The Apnea-Hypopnea Index (AHI) was computed. Patient-ventilator disconnections ≥3 minutes and episodes of hypoventilation defined as PtcCO2>45 mmHg were counted. Patient-ventilator asynchrony events were analyzed. The AHI was >5 hour(-1) in two patients. Another patient experienced unexplained 3% drops in arterial oxygen saturations at a frequency of 70 hour(-1). Patient-ventilator disconnections ≥3 minutes occurred in seven of eight patients and were consistently associated with decreases in SpO2 and ≥5-mmHg increases in PtcCO2; PtcCO2 rose above 45 mmHg in two patients during these disconnections. The most common type of patient-ventilator asynchrony was ineffective effort. This study confirms that MPV can be effective as long as the patient remains connected to the mouthpiece. However, transient arterial oxygen desaturation and hypercapnia due to disconnection from the ventilator may occur, without inducing unpleasant sensations in the patients. Therefore, an external warning system based on a minimal acceptable value of minute ventilation would probably be useful.

Agranulocytosis induced by proton pump inhibitors.

We report the first published case of agranulocytosis induced by omeprazole and its recurrence with esomeprazole, the S-isomer form of omeprazole. Interestingly, we found an homozygotous mutation of CYP2C19*17, responsible for the metabolism of proton pump inhibitors.

The modified Medical Research Council scale for the assessment of dyspnea in daily living in obesity: a pilot study.

BACKGROUND: Dyspnea is very frequent in obese subjects. However, its assessment is complex in clinical practice. The modified Medical Research Council scale (mMRC scale) is largely used in the assessment of dyspnea in chronic respiratory diseases, but has not been validated in obesity. The objectives of this study were to evaluate the use of the mMRC scale in the assessment of dyspnea in obese subjects and to analyze its relationships with the 6-minute walk test (6MWT), lung function and biological parameters. METHODS: Forty-five obese subjects (17 M/28 F, BMI: 43 ± 9 kg/m2) were included in this pilot study. Dyspnea in daily living was evaluated by the mMRC scale and exertional dyspnea was evaluated by the Borg scale after 6MWT. Pulmonary function tests included spirometry, plethysmography, diffusing capacity of carbon monoxide and arterial blood gases. Fasting blood glucose, total cholesterol, triglyceride, N-terminal pro brain natriuretic peptide, C-reactive protein and hemoglobin levels were analyzed. RESULTS: Eighty-four percent of patients had a mMRC ≥ 1 and 40% a mMRC ≥ 2. Compared to subjects with no dyspnea (mMRC = 0), a mMRC ≥ 1 was associated with a higher BMI (44 ± 9 vs 36 ± 5 kg/m2, p = 0.01), and a lower expiratory reserve volume (ERV) (50 ± 31 vs 91 ± 32%, p = 0.004), forced expiratory volume in one second (FEV1) (86 ± 17 vs 101 ± 16%, p = 0.04) and distance covered in 6MWT (401 ± 107 vs 524 ± 72 m, p = 0.007). A mMRC ≥ 2 was associated with a higher Borg score after the 6MWT (4.7 ± 2.5 vs 6.5 ± 1.5, p < 0.05). CONCLUSION: This study confirms that dyspnea is very frequent in obese subjects. The differences between the "dyspneic" and the "non dyspneic" groups assessed by the mMRC scale for BMI, ERV, FEV1 and distance covered in 6MWT suggests that the mMRC scale might be an useful and easy-to-use tool to assess dyspnea in daily living in obese subjects.

Nocturnal oximetry and transcutaneous carbon dioxide in home-ventilated neuromuscular patients.

BACKGROUND: Pulse oximetry alone has been suggested to determine which patients on home mechanical ventilation (MV) require further investigation of nocturnal gas exchange. In patients with neuromuscular diseases, alveolar hypoventilation (AH) is rarely accompanied with ventilation-perfusion ratio heterogeneity, and, therefore, oximetry may be less sensitive for detecting AH than in patients with lung disease. OBJECTIVE: To determine whether pulse oximetry (S(pO(2))) and transcutaneous carbon dioxide (P(tcCO(2))) during the same night were interchangeable or complementary for assessing home MV efficiency in patients with neuromuscular diseases. METHODS: Data were collected retrospectively from the charts of 58 patients with chronic neuromuscular respiratory failure receiving follow-up at a home MV unit. S(pO(2)) and P(tcCO(2)) were recorded during a 1-night hospital stay as part of standard patient care. We compared AH detection rates by P(tcCO(2)), S(pO(2)), and both. RESULTS: AH was detected based on P(tcCO(2)) alone in 24 (41%) patients, and based on S(pO(2)) alone with 3 different cutoffs in 3 (5%), 8 (14%), and 13 (22%) patients, respectively. Using both P(tcCO(2)) and S(pO(2)) showed AH in 25 (43%) patients. CONCLUSIONS: Pulse oximetry alone is not sufficient to exclude AH when assessing home MV efficiency in patients with neuromuscular diseases. Both P(tcCO(2)) and S(pO(2)) should be recorded overnight as the first-line investigation in this population.

Improvement of dyspnea after bariatric surgery is associated with increased Expiratory Reserve Volume: A prospective follow-up study of 45 patients.

OBJECTIVES: To assess the effects of bariatric surgery in patients with obesity on dyspnea and to analyze the relationships between improvement of dyspnea after bariatric surgery and changes in pulmonary function, especially Expiratory Reserve Volume (ERV) which is the lung volume abnormality most frequently associated with obesity. METHODS: Forty-five patients (5 males/40 females, mean Body Mass Index = 46.2 ± 6.8 kg/m2) were evaluated before and 6 to 12 months after bariatric surgery. Dyspnea was assessed by the modified Medical Research Council (mMRC) scale. Pulmonary function tests, arterial blood gases and six-minute walk test were performed. Laboratory parameters including C-Reactive Protein (CRP) were analyzed. RESULTS: Ninety percent of patients were dyspneic before surgery (mMRC scale ≥ 1) versus 59% after surgery (p<0.001). Mean mMRC score improved after bariatric surgery (1.5 ± 0.9 vs 0.7 ± 0.7, p<0.0001). Among patients with dyspnea before surgery (n = 38), a more marked increase in ERV after surgery was observed in patients with improvement of dyspnea compared to patients with no improvement of dyspnea (+0.17 ± 0.32 L vs +0.49 ± 0.35 L, p = 0.01). Multivariate analysis including age, variation of BMI, variation of CRP, variation of Total Lung Capacity and variation of ERV demonstraded that ERV was the only variable associated with improvement of the mMRc score after bariatric surgery (p = 0.04). CONCLUSION: Weight loss associated with bariatric surgery improves dyspnea in daily living. This improvement could be partly related to increased ERV.

Prognostic Value of Initial Assessment of Residual Hypoventilation Using Nocturnal Capnography in Mechanically Ventilated Neuromuscular Patients: A 5-Year Follow-up Study.

BACKGROUND: Restrictive respiratory failure is a major cause of morbidity and mortality in neuromuscular diseases (NMD). Home mechanical ventilation (HMV) is used to treat hypoventilation, and its efficiency is mostly assessed by daytime blood gases or nocturnal oxygen saturation monitoring (SpO2). Non-invasive transcutaneous measure of CO2 (TcCO2) allows to directly assess nocturnal hypercapnia and to detect residual hypoventilation with a higher sensitivity than SpO2. We aimed to compare the prognostic value of nocturnal SpO2 and TcCO2 in ventilated adult NMD patients. METHODS: All consecutive capno-oximetries performed between 2010 and 2011 in ventilated adult NMD patients were analyzed retrospectively. Concomitant blood gas analysis and lung function data were collected. Patients on oxygen therapy were excluded. Nocturnal hypoxemia and hypercapnia (using four different definitions) at baseline were compared in their ability to predict mortality and respiratory events requiring ICU admission during follow-up. RESULTS: Data from 55 patients were analyzed (median age 28 [interquartile range: 25-36.5] years; 71% Duchenne muscular dystrophy; vital capacity 12 [7-27]% of predicted; 51% tracheostomy). Capno-oxymetry showed hypoxemia in 14.5% and hypercapnia in 12.7-41.8%, according to the used definition. Over a follow-up lasting up to 5 years (median 4.0 [3.6-4.5] years), we observed 12 deaths and 20 respiratory events requiring ICU admission. Hypercapnia was significantly associated with the study outcomes, with TcCO2 > 49 mmHg during ≥10% of the time being the best definition, while hypoxemia was not. CONCLUSION: Our data show for the first time that residual hypoventilation, assessed by capnometry, is significantly associated with negative outcomes in adult ventilated NMD patients, while oximetry is not. Accordingly, we suggest capnometry to be included in the systematic assessment of HMV efficiency in NMD patients. CLINICALTRIALSGOV IDENTIFIER: NCT02551406.

Efficiency of invasive mechanical ventilation during sleep in Duchenne muscular dystrophy.

OBJECTIVE: Inspiratory unintentional leaks (IULs) during noninvasive ventilation (NIV) adversely affect the sleep and the effectiveness of mechanical ventilation (MV). The aim of this study was to assess the effects of nocturnal IULs in Duchenne muscular dystrophy (DMD) patients with a tracheostomy and uncuffed tube comparatively with NIV patients. METHODS: Polysomnography with transcutaneous partial pressure of carbon dioxide (PtcCO(2)) recording and blood gas measurement was performed in 26 stable tracheostomized DMD patients using home MV, among whom 11 were matched with NIV patients. RESULTS: IULs occurred during 29.4% [1.7-61.9%] (median [IQR]) of the total sleep time. By univariate regression analysis, the closest correlation with IUL duration was for daytime base excess (r(2)=0.69, P<0.0001), followed by daytime bicarbonate level. In a stepwise multiple regression analysis, only base excess remained significantly correlated. Sleep and respiratory parameters improved in the four patients who agreed to use cuffed tubes. Tracheostomized patients had lower maximal PtcCO(2) (P=0.02) and base excess values (P=0.045) compared to NIV controls. CONCLUSION: Tracheostomy does not guarantee that MV is effective during sleep, as IULs may occur, but ensures better nocturnal gas exchanges than NIV. DMD patients should be evaluated using at least blood gas measurement, nocturnal oximetry, and PtcCO(2) monitoring.