Data automated bag breathing unit for COVID-19 ventilator shortages.

BACKGROUND: The COVID-19 pandemic has caused a global mechanical ventilator shortage for treatment of severe acute respiratory failure. Development of novel breathing devices has been proposed as a low cost, rapid solution when full-featured ventilators are unavailable. Here we report the design, bench testing and preclinical results for an 'Automated Bag Breathing Unit' (ABBU). Output parameters were validated with mechanical test lungs followed by animal model testing. RESULTS: The ABBU design uses a programmable motor-driven wheel assembled for adult resuscitation bag-valve compression. ABBU can control tidal volume (200-800 ml), respiratory rate (10-40 bpm), inspiratory time (0.5-1.5 s), assist pressure sensing (- 1 to - 20 cm H2O), manual PEEP valve (0-20 cm H2O). All set values are displayed on an LCD screen. Bench testing with lung simulators (Michigan 1600, SmartLung 2000) yielded consistent tidal volume delivery at compliances of 20, 40 and 70 (mL/cm H2O). The delivered fraction of inspired oxygen (FiO2) decreased with increasing minute ventilation (VE), from 98 to 47% when VE was increased from 4 to 16 L/min using a fixed oxygen flow source of 5 L/min. ABBU was tested in Berkshire pigs (n = 6, weight of 50.8 ± 2.6 kg) utilizing normal lung model and saline lavage induced lung injury. Arterial blood gases were measured following changes in tidal volume (200-800 ml), respiratory rate (10-40 bpm), and PEEP (5-20 cm H2O) at baseline and after lung lavage. Physiological levels of PaCO2 (≤ 40 mm Hg [5.3 kPa]) were achieved in all animals at baseline and following lavage injury. PaO2 increased in lavage injured lungs in response to incremental PEEP (5-20 cm H2O) (p < 0.01). At fixed low oxygen flow rates (5 L/min), delivered FiO2 decreased with increased VE. CONCLUSIONS: ABBU provides oxygenation and ventilation across a range of parameter settings that may potentially provide a low-cost solution to ventilator shortages. A clinical trial is necessary to establish safety and efficacy in adult patients with diverse etiologies of respiratory failure.

Adherence to an Oxygen-Weaning Protocol in Mechanically Ventilated Adults in the Medical ICU.

BACKGROUND: Patients undergoing mechanical ventilation in the ICU often receive supplemental oxygen. If not closely monitored, this may lead to hyperoxia. The use of an oxygen-weaning protocol may reduce this risk by pacing the titration of oxygen therapy to patient needs. ICU protocols are correlated with decreased mortality and length of stay and have great potential for cost savings. The goals of this study were to determine whether the oxygen-weaning protocol at a university-affiliated hospital was followed and to measure the length of time respiratory therapists took to wean patients once the oxygen-weaning parameters were met. METHODS: This was a retrospective chart review of subjects > 18 y of age admitted to the medical ICU who underwent intubation and mechanical ventilation and were placed on an oxygen therapy protocol. The following data were collected: demographics, arterial blood gases, the length of time to change [Formula: see text] after meeting weaning parameters, and the percent change in [Formula: see text]. RESULTS: Data were collected from 30 subjects. The most common oxygen saturation parameter measured via pulse oximetry ([Formula: see text]) used to initiate weaning oxygen was 92%. The mean ± SD [Formula: see text] administered to subjects was 39.6 ± 15.3% prior to extubation. The majority of subjects exhibited adequate oxygenation prior to extubation (mean ± SD): [Formula: see text] 99.3 ± 6.7 mm Hg, [Formula: see text] 95.1 ± 26.9%. The mean ± SD length of time to the first change in [Formula: see text] from the time a subject met the weaning criteria was 9.1 ± 10.6 h (range 1-39 h; interquartile range 2-13 h). CONCLUSIONS: Subjects admitted to the medical ICU who were intubated, mechanically ventilated, and placed on the oxygen therapy protocol experienced a significant delay in oxygen weaning. Closer monitoring and adherence to the oxygen-weaning protocol should be considered to reduce the potential risk for hyperoxia.

Endotracheal cuff pressures in the PICU: Incidence of underinflation and overinflation.

BACKGROUND: While uncuffed endotracheal tubes have been traditionally used in the pediatric intensive care unit (PICU) population, evidence suggests cuffed endotracheal tubes (ETTs) are also safe to use within this population. Nevertheless, risks related to the use of cuffed ETTs increase when guidelines for safe and appropriate use are not followed. The primary goal of this study was to measure the cuff pressure (CP) using a cuff pressure manometer in a group of intubated pediatric subjects and determine the rate of cuff underinflation (<20 cm H20) or overinflation (>30 cm H20). The secondary aim was to determine whether CP was associated to gender, age, ETT size, and PICU length of stay prior to CP measurement. METHODS: This was a prospective observational study conducted in an urban PICU. Pediatric subjects intubated with cuffed ETTs from 1 April 2017 to 1 May 2017 were included in the study. ETT CPs were measured daily to determine degree of inflation and compared according to gender, age, ETT size, and number of days intubated prior to CP measurement. Descriptive data are expressed as means and standard deviations. A two-sample t test was used to compare groups according to age, gender, and number of days present. And significance was considered with a P < 0.05. Pearson chi test was used to evaluate correlation between CPs and size of the ETT, number of days intubated prior to CP measurement, gender, and age. RESULTS: Twenty pediatric subjects admitted during the study period were included for analysis. Eleven cuff measurements were found to be within normal limits, while 9 cuff measurements were found to be underinflated. No cases of overinflation were found. There were no significant associations between CP and size of the ETT (r = -0.08), number of days intubated prior to CP measurement (r = 0.19), gender (r = 0.09), and age (r = 0.12). CONCLUSIONS: Our study suggests that endotracheal cuff underinflation occurs often in the PICU population. Strategies to ensure appropriate ETT CPs are maintained are essential in the intubated pediatric population. Additional studies are necessary to develop interventions and training focused on the use of a cuff pressure manometer to measure CPs in the PICU by respiratory therapists and ensure consistent measurement using inter rater evaluation processes are needed.

AARC clinical practice guideline: transcutaneous monitoring of carbon dioxide and oxygen: 2012.

An electronic literature search for articles published between January 1990 and September 2011 was conducted by using the PubMed, CINAHL, SCOPUS, and Cochrane Library databases. The update of this clinical practice guideline is the result of reviewing a total of 124 articles: 3 randomized controlled trials, 103 prospective trials, 1 retrospective study, 3 case studies, 11 review articles, 2 surveys and 1 consensus paper on transcutaneous monitoring (TCM) for P(tcO(2)) and P(tcCO(2)). The following recommendations are made following the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) criteria: (1) Although P(tcCO(2)) has a good correlation with P(aCO(2)) and is a reliable method to evaluate plasma CO(2) levels, it is recommended that arterial blood gas values be compared to transcutaneous readings taken at the time of arterial sampling, in order to verify the transcutaneous values, and periodically as dictated by the patient's clinical condition. (2) It is suggested that P(tcCO(2)) may be used in clinical settings where monitoring the adequacy of ventilation is indicated. (3) It is suggested that P(tcO(2)) and P(tcCO(2)) may be used in determining the adequacy of tissue perfusion and monitoring of reperfusion. (4) It is suggested that TCM should be avoided in the presence of increased thickness or edema of the skin and/or subcutaneous tissue where the sensor is applied. (5) It is recommended that sites used for a TCM be changed as often as necessary and that they be alternated and observed to avoid thermal injury. Manufacturer recommendations should be followed.

Incentive spirometry: 2011.

We searched the MEDLINE, CINAHL, and Cochrane Library databases for articles published between January 1995 and April 2011. The update of this clinical practice guideline is the result of reviewing a total of 54 clinical trials and systematic reviews on incentive spirometry. The following recommendations are made following the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) scoring system. 1: Incentive spirometry alone is not recommended for routine use in the preoperative and postoperative setting to prevent postoperative pulmonary complications. 2: It is recommended that incentive spirometry be used with deep breathing techniques, directed coughing, early mobilization, and optimal analgesia to prevent postoperative pulmonary complications. 3: It is suggested that deep breathing exercises provide the same benefit as incentive spirometry in the preoperative and postoperative setting to prevent postoperative pulmonary complications. 4: Routine use of incentive spirometry to prevent atelectasis in patients after upper-abdominal surgery is not recommended. 5: Routine use of incentive spirometry to prevent atelectasis after coronary artery bypass graft surgery is not recommended. 6: It is suggested that a volume-oriented device be selected as an incentive spirometry device.

Critical-thinking ability in respiratory care students and its correlation with age, educational background, and performance on national board examinations.

BACKGROUND: Critical thinking is an important characteristic to develop in respiratory care students. METHODS: We used the short-form Watson-Glaser Critical Thinking Appraisal instrument to measure critical-thinking ability in 55 senior respiratory care students in a baccalaureate respiratory care program. We calculated the Pearson correlation coefficient to assess the relationships between critical-thinking score, age, and student performance on the clinical-simulation component of the national respiratory care boards examination. We used chi-square analysis to assess the association between critical-thinking score and educational background. RESULTS: There was no significant relationship between critical-thinking score and age, or between critical-thinking score and student performance on the clinical-simulation component. There was a significant (P = .04) positive association between a strong science-course background and critical-thinking score, which might be useful in predicting a student's ability to perform in areas where critical thinking is of paramount importance, such as clinical competencies, and to guide candidate-selection for respiratory care programs.

Medication adherence issues in patients treated for COPD.

Although medical treatment of COPD has advanced, nonadherence to medication regimens poses a significant barrier to optimal management. Underuse, overuse, and improper use continue to be the most common causes of poor adherence to therapy. An average of 40%-60% of patients with COPD adheres to the prescribed regimen and only 1 out of 10 patients with a metered dose inhaler performs all essential steps correctly. Adherence to therapy is multifactorial and involves both the patient and the primary care provider. The effect of patient instruction on inhaler adherence and rescue medication utilization in patients with COPD does not seem to parallel the good results reported in patients with asthma. While use of a combined inhaler may facilitate adherence to medications and improve efficacy, pharmacoeconomic factors may influence patient's selection of both the device and the regimen. Patient's health beliefs, experiences, and behaviors play a significant role in adherence to pharmacological therapy. This manuscript reviews important aspects associated with medication adherence in patients with COPD and identifies some predictors of poor adherence.

Delivered oxygen concentrations using low-flow and high-flow nasal cannulas.

INTRODUCTION: Nasal cannulas are commonly used to deliver oxygen in acute and chronic care settings; however, there are few data available on delivered fraction of inspired oxygen (F(IO(2))). The purposes of this study were to determine the delivered F(IO(2)) on human subjects using low-flow and high-flow nasal cannulas, and to determine the effects of mouth-closed and mouth-open breathing on F(IO(2)). METHODS: We measured the pharyngeal F(IO(2)) delivered by adult nasal cannulas at 1-6 L/min and high-flow nasal cannulas at 6-15 L/min consecutively in 10 normal subjects. Oxygen was initiated at 1 L/min, with the subject at rest, followed by a period of rapid breathing. Gas samples were aspirated from a nasal catheter positioned with the tip behind the uvula. This process was repeated at each liter flow. Mean, standard deviation, and range were calculated at each liter flow. F(IO(2)) during mouth-open and mouth-closed breathing were compared using the dependent test for paired values, to determine if there were significant differences. RESULTS: The mean resting F(IO(2)) ranged from 0.26-0.54 at 1-6 L/min to 0.54-0.75 at 6-15 L/min. During rapid breathing the mean F(IO(2)) ranged from 0.24-0.45 at 1-6 L/min to 0.49-0.72 at 6-15 L/min. The mean F(IO(2)) increased with increasing flow rates. The standard deviation (+/- 0.04-0.15) and range were large, and F(IO(2)) varied widely within and between subjects. F(IO(2)) during mouth-open breathing was significantly (p < 0.05) greater than that during mouth-closed breathing. CONCLUSIONS: F(IO(2)) increased with increasing flow. Subjects who breathed with their mouths open attained a significantly higher F(IO(2)), compared to those who breathed with their mouths closed.