Association between Angiotensin-Converting Enzyme Inhibitors and Angiotensin Receptor Blockers and Lung Cancer.

OBJECTIVES: Angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) are the most commonly prescribed antihypertensives, with prior studies identifying a possible association between long-term use and increased rates of lung cancer. This study evaluated this potential association in a large population using propensity matching. METHODS: This was a population-based cohort study in a large healthcare system in three regions of the United States. Pairwise propensity score matching was performed using demographics and comorbidities. All of the adult patients in the healthcare system from January 1, 2000 to April 30, 2018 with at least 1 year of follow-up were included. RESULTS: In total, 3,253,811 patients with a median age of 59 (range 18-103) years were included. The ACEI group had a higher freedom from lung cancer versus controls at 15 years (98.47%, 95% confidence interval [CI] 98.41-98.54) versus 98.26%, (95% CI 98.20-98.33), whereas ARBs had similar rates versus controls at all time points. For patients diagnosed as having lung cancer, median all-cause survival was significantly higher in the ACEI (34.7 months, 95% CI 32.8-36.6) and ARB (30.9 months, 95% CI 28.1-33.8) groups than the control group (20.6 months, 95% CI 20.1-21.1). CONCLUSIONS: This study showed lower rates of lung cancer with ACEI use and no difference in risk with ARBs. In addition, use of these medications was found to be associated with increased survival in those diagnosed as having lung cancer. This study supports the continued use of these medications without concern for increasing the risk of lung cancer.

The Use of an Interleukin-6 Inhibitor in Vasoplegic Shock from Severe Systemic Inflammatory Response Syndrome: A Case Report.

A 66-year-old Caucasian male with a history of chronic myelomonocytic leukemia (CMML) developed fluid-unresponsive hypotension requiring initiation of four different maximum dosed vasopressors, steroids, and broad-spectrum antibiotics 4 hours following four-vessel coronary artery bypass grafting involving a 150-minute cardiac bypass. Placement of a Swanz-Ganz catheter showed a cardiac output of 7 L/minute with systemic vascular resistance of 571 dynes/sec/cm-5. Over 24 hours, three doses of tocilizumab (interleukin-6 inhibitor) every 8 hours were initiated, plus 250 mg methylprednisolone per 6 hours increment, and then daily thereafter. After the initial dose of tocilizumab, it was possible to wean vasoconstrictors. We have shown for the first time that therapy with tocilizumab is effective in reversing the hemodynamic instability associated with the significant systemic inflammatory response from the "double hit" of CMML and coronary artery bypass grafting with cardiopulmonary bypass as has previously been shown in cytokine release syndrome. How to cite this article: Elkhatib WY, Saunders H, Helgeson SA, Moss JE. The Use of an Interleukin-6 Inhibitor in Vasoplegic Shock from Severe Systemic Inflammatory Response Syndrome: A Case Report. Indian J Crit Care Med 2021;25(8):939-941.

Reducing Iatrogenic Pneumothoraces: Using Real-Time Ultrasound Guidance for Pleural Procedures.

OBJECTIVES: Awareness of the impact of bedside ultrasound to reduce iatrogenic pneumothoraces while performing bedside pleural procedures has increased but with little understanding in how ultrasound is used for these procedures. DESIGN AND SETTING: We conducted a retrospective chart review at a tertiary referral center in the United States from January 1, 2014, to March 31, 2017. Our study assessed adverse effect rates between real-time ultrasound-guided and ultrasound-marked thoracenteses and thoracostomy tube placements. PATIENTS: Three-hundred ninety-four ICU patients were included in this study. MEASUREMENTS AND MAIN RESULTS: There was a significant difference in the rate of adverse effects between real-time ultrasound-guided (0.63% [95% CI, 0.11-3.4%]) and ultrasound-marked (6.89% [95% CI, 4.15-11.24%]; p ≤ 0.01) procedures. More specifically, the rate of pneumothoraces was different between the two procedures (0.63% [95% CI, 0.11-3.4%] vs 4.43% [95% CI, 2.35-8.21%]; p = 0.02). In patients mechanically ventilated, there was a significant difference in overall adverse effect rates between groups of ultrasound use (p = 0.01). CONCLUSIONS: The use of real-time ultrasound guidance was associated with a lower rate of iatrogenic pneumothoraces.

Implementation of a New Guideline and Educational Sessions to Reduce Low-Value Continuous Pulse Oximetry Among Hospitalized Patients.

OBJECTIVES: The use of continuous pulse oximetry (CPOX) is ubiquitous among hospitalized patients, despite limited evidence that it improves clinical outcomes. The objective of this study was to reduce the use of CPOX among hospitalized patients in the nonintensive care unit and nonprogressive care unit settings. METHODS: This interventional trial included the creation a new local guideline for CPOX use and subsequent staff education. CPOX use, patient acuity, hospital length of stay, and code blue events were measured before and after the intervention. RESULTS: Postintervention there was a clinically significant and sustained decrease in CPOX use of 18% over 1 year. There were no significant changes postintervention in hospital length of stay or number of code blue events. CONCLUSIONS: Development of a guideline for CPOX use and staff education successfully led to a decrease in CPOX use, without an increase in hospital length of stay or code blue events.

First Reported Case of Respiratory Syncytial Virus Infection Causing Guillain-Barré Syndrome.

Acute immune-mediated polyneuropathies are a group of illnesses that cause paralysis following an infection. We describe a case of one of these illnesses being caused by the respiratory syncytial virus (RSV). An 81-year-old female was admitted for an RSV infection. She went into respiratory failure requiring intubation and mechanical ventilation and treatment with ribavirin. When she was extubated, she had bilateral lower extremity weakness and absent reflexes. Her disease progressed rapidly to involve her diaphragm, and eventually, the family agreed to let the natural death process occur. Our case is the first reported case in which an acute immune-mediated polyneuropathy was caused from an RSV infection.

Association of estimated plasma volume with new onset acute kidney injury in hospitalized COVID-19 patients.

PURPOSE: To explore the association of estimated plasma volume (ePV) and plasma volume status (PVS) as surrogates of volume status with new-onset AKI and in-hospital mortality among hospitalized COVID-19 patients. MATERIALS AND METHODS: We performed a retrospective multi-center study on COVID-19-related ARDS patients who were admitted to the Mayo Clinic Enterprise health system. Plasma volume was calculated using the formulae for ePV and PVS, and longitudinal analysis was performed to find the association of ePV and PVS with new-onset AKI during hospitalization as the primary outcome and in-hospital mortality as a secondary outcome. RESULTS: Our analysis included 7616 COVID-19 patients with new-onset AKI occurring in 1365 (17.9%) and a mortality rate of 25.96% among them. A longitudinal multilevel multivariate analysis showed both ePV (OR 1.162; 95% CI 1.048-1.288, p=0.004) and PVS (OR 1.032; 95% CI 1.012-1.050, p=0.001) were independent predictors of new onset AKI. Higher PVS was independently associated with increased in-hospital mortality (OR 1.038, 95% CI 1.007-1.070, p=0.017), but not ePV (OR 0.868, 95% CI 0.740-1.018, p=0.082). CONCLUSION: A higher PVS correlated with a higher incidence of new-onset AKI and worse outcomes in our cohort of hospitalized COVID-19 patients. Further large-scale and prospective studies are needed to understand its utility.

Impact of concomitant gastroesophageal reflux disease symptomology on prognosis and pulmonary function of chronic hypersensitivity pneumonitis.

Background and Objectives: Comorbid risk factors in chronic hypersensitivity pneumonitis (CHP) are poorly characterised. Gastroesophageal reflux disease (GERD) is linked to interstitial lung diseases like idiopathic pulmonary fibrosis (IPF), but its association and treatment in CHP is less understood. This study aims to understand the role and prevalence of GERD in CHP, plus the effect of GERD treatment on lung function and mortality. Methods: A tertiary referral centre panel was retrospectively reviewed for 214 patients diagnosed with CHP based on clinical history, bronchoalveolar lavage fluid analysis, imaging and histopathology. GERD diagnostic criteria included symptomology, acid suppressive therapy use and diagnostic testing. CHP patients with GERD (n = 89) and without GERD (n = 125) were compared via descriptive statistical analysis. Pulmonary function, GERD diagnosis plus treatment and other comorbidities were evaluated against CHP outcomes. Results: Respective differences between diagnosis and study termination dates in the GERD population versus without GERD for functional vital capacity (FVC) were - 1 L vs - 2.5 L, diffusing capacity of the lungs for carbon monoxide (DLCO) were - 2 mL/min/mmHg versus - 1 mL/min/mmHg, per cent alive at the time of study 88% versus 81%, median date of survival 574.5 versus 850 and supplemental oxygen requirement 41% versus 37%. GERD prevalence was higher in CHP patients relative to the general population. No statistical significance was found between survival curves, oxygen requirement, smoking history, FVC, or DLCO. Conclusions: GERD could be a harmful comorbidity in CHP though may not necessarily affect survival or functional outcomes. This aligns with previous IPF studies, though remains controversial. Further research is needed regarding this association and treatment benefit.

The Association between Non-Invasive Ventilation and the Rate of Ventilator-Associated Pneumonia.

Ventilator-associated pneumonia (VAP) has significant effects on patient outcomes, including prolonging the duration of both mechanical ventilation and stay in the intensive care unit (ICU). The aim of this study was to assess the association between non-invasive ventilation/oxygenation (NIVO) prior to intubation and the rate of subsequent VAP. This was a multicenter retrospective cohort study of adult patients who were admitted to the medical ICU from three tertiary care academic centers in three distinct regions. NIVO was defined as continuous positive airway pressure (CPAP), bilevel positive airway pressure (BiPAP), or high-flow nasal cannula (HFNC) for any duration during the hospitalization prior to intubation. The primary outcome variable was VAP association with NIVO. A total of 17,302 patients were included. VAP developed in 2.6% of the patients (444/17,302), 2.3% (285/12,518) of patients among those who did not have NIVO, 1.6% (30/1879) of patients who had CPAP, 2.5% (17/690) of patients who had HFNC, 8.1% (16/197) of patients who had BiPAP, and 4.8% (96/2018) of patients who had a combination of NIVO types. Compared to those who did not have NIVO, VAP was more likely to develop among those who had BiPAP (adj OR 3.11, 95% CI 1.80-5.37, p < 0.001) or a combination of NIVO types (adj OR 1.91, 95% CI 1.49-2.44, p < 0.001) after adjusting for patient demographics and comorbidities. The use of BiPAP or a combination of NIVO types significantly increases the odds of developing VAP once receiving IMV.

Does COVID-19 impair V̇o2peak in patients with cardiorespiratory disease? Insight from cardiopulmonary responses to maximal exercise pre- and post-illness.

Reduced exercise capacity has been suggested as a cardinal sequela of COVID-19. However, only cross-sectional approaches that either do not consider individuals with concomitant cardiorespiratory disease or account for exercise capacity before infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) support this assumption. Is reduced exercise capacity a sequela of SARS-CoV-2 infection in patients with concomitant cardiorespiratory disease? We retrospectively reviewed cardiopulmonary exercise testing (CPET) data collected across three hospitals between October 2018 and March 2022. Forty-two patients who completed a CPET before and after COVID-19 and 25 patients who performed two separate CPETs but did not contract COVID-19 (CTL) were included. Within each patient, the same test protocol was performed at the first and second CPETs. The time between CPETs was similar between the groups (COVID-19 489 ± 534 vs. CTL 534 ± 257 days, P = 0.662). The COVID-19 group performed the CPETs 312 ± 232 days before and 176 ± 110 days after infection. Exercise time, peak heart rate, peak systolic pressure, oxygen uptake (V̇o2) at anaerobic threshold, peak ventilation, and ventilatory efficiency were not different between the CPETs in both groups. Peak V̇o2 was reduced from before to after SARS-CoV-2 infection. However, the change in V̇o2peak from the first to the second CPET was not different between COVID-19 vs. CTL. Accounting for V̇o2peak before COVID-19 and including a group of control patients, we find limited evidence for reduced exercise capacity as a sequela of SARS-CoV-2 infection in patients with concomitant cardiorespiratory disease.NEW & NOTEWORTHY There is accumulating evidence that reduced exercise capacity is, or can be, an outcome following COVID-19. However, evidence to date relies upon cross-sectional approaches that either do not consider patients with concomitant cardiorespiratory disease or account for pre-infection exercise capacity data. Accounting for V̇o2peak before COVID-19 and including a group of control patients, we find limited evidence for reduced exercise capacity as a sequela of SARS-CoV-2 infection in patients with concomitant cardiorespiratory disease.

Early Versus Usual Palliative Care Consultation in the Intensive Care Unit.

OBJECTIVES: Palliative Medicine involvement in MICU patients have improved length of stay and mortality, but with varying effects on specific patient decision outcomes, such as, advance care planning. These studies have utilized Palliative Medicine later in the hospital or ICU course, with some evidence showing that earlier involvement resulted in better results. The purpose of this study was to evaluate the benefits of early (within 24 hours) palliative care consultation in medical ICU (MICU) patients to clinical and satisfaction outcomes. METHODS: An unblinded randomized study performed in the MICU in one academic hospital in the USA. Ninety-one adult patients admitted to MICU received a Palliative care medicine consultation within 24 hours as the intervention. MEASUREMENTS AND RESULTS: Ninety-one patients admitted to the MICU underwent randomization with 50 patients randomly assigned to receive Palliative Medicine consultation and 41 patients randomly assigned to receive standard-of-care based on predefined criteria. The median satisfaction score was 23 points higher for the patients in the intervention group (P < .001). The median length of MICU stay was 5 days shorter in the intervention group compared to the control group (95% CI; 1 day to 18 days, P = .018). Advance care planning was completed in the hospital for 34% of patients in the intervention arm and 12% of patients in the controls arm (absolute risk difference 22%, 95% CI 4% to 37%, P = .016). CONCLUSION: Early Palliative Medicine consultation within 24 hours of MICU admission showed significant benefits to patients by improving satisfaction and decreasing length of stay. This study provides evidence that Palliative Medicine involvement earlier in the course of severe disease is important. Further studies in other types of intensive care units (neurological and Cardiovascular) are necessary to determine their impact.

Simulation Method for Testing Aerosol Mitigation Strategies: An Observational Study.

BACKGROUND: Frontline health care workers who perform potentially aerosol-generating procedures, such as endotracheal intubations, in patients with coronavirus disease 2019 may be at an increased risk of exposure to severe acute respiratory syndrome coronavirus 2. To continue to care for patients with coronavirus disease 2019, minimizing exposure is paramount. Using simulation, we devised a testing method to evaluate devices that may mitigate the spread of aerosol and droplet-sized particles. METHODS: In this prospective single-center study, participants intubated a manikin 3 times using standard personal protective equipment, once with no barrier device, once with an acrylic box, and once with a modified horizontal drape. The micrometer-sized particle count, generated by a nebulization model, was recorded before and after each intubation. The first-pass intubation rate and time to intubation were recorded. Each operator completed a postsimulation survey about their experience using the barrier devices. RESULTS: Thirty airway proceduralists completed the simulation and survey. There was no significant difference in particle counts (aerosols or droplets) or first-pass intubation, but the horizontal drape was found to significantly increase intubation time ( P = 0.01). Most participants preferred the drape over the acrylic box or no barrier device. CONCLUSIONS: The acrylic box and plastic drape did not mitigate particle spread. However, our testing method can be used to test barrier designs using negative pressure or other mitigation strategies for particle spread.

Comparing Diagnosis and Treatment of Pulmonary Hypertension Patients at a Pulmonary Hypertension Center versus Community Centers.

Once patients are diagnosed with pulmonary hypertension it is important to identify the correct diagnostic group as it will have implications on the disease state management. Pulmonary hypertension is increasingly diagnosed and treated in general medical practices; however, evidence-based guidelines recommend evaluation and treatment in pulmonary hypertension centers for accurate diagnosis and appropriate treatment recommendations. We conducted a retrospective cohort study of 509 random patients 18 years and older who were evaluated in our pulmonary hypertension clinic from January 2005 to December 2018. 68.4% (n = 348) had their diagnostic group clarified or changed. Pulmonary hypertension was deemed an incorrect diagnosis in 12.4% (n = 63). A total of 114 patients (22.4%) had been initiated on pulmonary hypertension specific treatment prior to presentation. Pulmonary hypertension specific medication was stopped in 57 (50.0%) cases. The estimated monthly saving of the stopped medication based on wholesale acquisition costs was USD 396,988.05-419,641.05, a monthly saving of USD 6964.70-7362.12 per patient. Evaluation outside of a pulmonary hypertension center may lead to misdiagnosis and inappropriate or inadequate treatment. Pulmonary arterial hypertension directed therapy improves median survival, but inappropriate therapy may cause harm; therefore, patients benefit from a specialized center with multiple resources to secure an accurate diagnosis and tailored treatment for their condition.

Bedside Clinicians' Perceptions on the Contributing Role of Diagnostic Errors in Acutely Ill Patient Presentation: A Survey of Academic and Community Practice.

OBJECTIVES: This study aimed to explore clinicians' perceptions of the occurrence of and factors associated with diagnostic errors in patients evaluated during a rapid response team (RRT) activation or unplanned admission to the intensive care unit (ICU). METHODS: A multicenter prospective survey study was conducted among multiprofessional clinicians involved in the care of patients with RRT activations and/or unplanned ICU admissions (UIAs) at 2 academic hospitals and 1 community-based hospital between April 2019 and March 2020. A study investigator screened eligible patients every day. Within 24 hours of the event, a research coordinator administered the survey to clinicians, who were asked the following: whether diagnostic errors contributed to the reason for RRT/UIA, whether any new diagnosis was made after RRT/UIA, if there were any failures to communicate the diagnosis, and if involvement of specialists earlier would have benefited that patient. Patient clinical data were extracted from the electronic health record. RESULTS: A total of 1815 patients experienced RRT activations, and 1024 patients experienced UIA. Clinicians reported that 18.2% (95/522) of patients experienced diagnostic errors, 8.0% (42/522) experienced a failure of communication, and 16.7% (87/522) may have benefitted from earlier involvement of specialists. Compared with academic settings, clinicians in the community hospital were less likely to report diagnostic errors (7.0% versus 22.8%, P = 0.002). CONCLUSIONS: Clinicians report a high rate of diagnostic errors in patients they evaluate during RRT or UIAs.

Facemasks and Walk Distance in Pulmonary Arterial Hypertension Patients.

Little is known about the effect of wearing a facemask on the physiological and perceptual responses to exercise in patients with pulmonary arterial hypertension (PAH). We performed a single-center retrospective study to evaluate whether facemask wearing impacted distanced covered, rating of perceived exertion (RPE), and arterial oxygen saturation (SpO2) during a 6-minute walk test (6MWT) in PAH patients. Forty-five patients being treated for group 1 PAH and who performed a 6MWT before and after implementation of a facemask mandate were included in the analysis. Each included patient performed a 6MWT without (test 1) and with (test 2) a facemask between October 1, 2019, and October 31, 2020. At both time points, all patients also underwent a submaximal cardiopulmonary exercise test, echocardiogram, and blood laboratory tests, with a Registry to Evaluate Early and Long-Term PAH Disease Management Lite 2.0 score calculated. The two 6MWTs were performed 81±51 days apart, and all patients were clinically stable at both testing timepoints. Six-minute walk test distance was not different between test 1 and test 2 (405±108 m vs 400±103 m, P=.81). Similarly, both end-test RPE and lowest SpO2 during the 6MWT were not different in test 1 and test 2 (RPE: 2.5±1.7 vs 2.5±2.1, P=.91; SpO2 nadir: 92.8±3.4% vs 93.3±3.3%, P=.55). Our findings show that wearing a facemask has no discernable impact on the arterial oxygen saturation and perceptual responses to exercise or exercise capacity in patients with moderate-to-severe PAH. This study reinforces the evidence that wearing a facemask is safe in PAH patients, even during exercise.

Particulate generation with different oxygen delivery devices.

BACKGROUND: The Coronavirus pandemic has a high mortality rate in patients that are mechanically ventilated, which has led to an ever increasing interest in noninvasive forms of oxygenation. The use of these devices has the theoretical risk of increased exposure risk because of possible particulate generation. This study aimed to quantify the particulate generation associated with different oxygen devices. METHODS: This was a prospective single center study conducted during September 2020 using ten healthy adult volunteers. Testing was conducted in a negative pressure hospital room using a light scattering particle counter. The oxygen devices used were a nasal cannula, an OxyMask™, a non-rebreathing mask, and a high flow system. Particle measurements were obtained at baseline in the room and then with each oxygen delivery device and pre-specified oxygen flow rates. These measurements were obtained different distances from the volunteer with their mouth open. A Wilcoxon/Kruskal-Wallis test was performed on each separate oxygen modality with all flow rates as one model. RESULTS: The particle concentrations were slightly non-significantly increased with the OxyMask™ and non-rebreathing mask at the closest distance measured. As the distance increased, these counts decreased closer to ambient levels. The nasal cannula and high flow nasal cannula particle counts were not significantly different from ambient measurements at either distance. CONCLUSION: Nasal cannula, OxyMask™, non-rebreathing mask, and high flow oxygen did not generate any additional aerosols or droplets above a baseline room measurement, but further studies are necessary to determine infectious risk.

Occult lymph node metastasis in radiologic stage I non-small cell lung cancer: The role of endobronchial ultrasound.

RATIONALE: The use of endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is currently recommended for staging non-small cell lung cancer (NSCLC) in centrally located tumors, tumors >3 cm, or with radiologic evidence of lymph node (LN) metastasis. Current guidelines do not recommend staging EBUS-TBNA in patients with stage I NSCLC who do not have any of the aforementioned conditions. OBJECTIVE: We hypothesize that using EBUS-TBNA is useful for detecting occult metastasis in radiologic stage I NSCLC. METHODS: In this single-center, retrospective study, charts of patients ≥18 years old who underwent staging EBUS-TBNA from January 2005 to May 2019 were reviewed. Only patients with combined positron-emission tomography and computed tomography (PET/CT) scans consistent with radiologic stage I NSCLC were included. Identified variables included: age, gender, personal history of any cancer, smoking history, tumor location, tumor centrality, tumor size, tumor PET activity, histopathologic type of NSCLC, and LN biopsy results. Patients whose LN samples showed a diagnosis other than NSCLC were excluded. The association between LN positivity, and each of the variables was assessed using Pearson's correlation for categorical variables, and logistic regression analysis for continuous variables. RESULTS: From the 2,892 initially screened patients, 188 were included. Of those, 13 (6.9%; 95% CI, 4%-11%) had a malignancy-positive LN biopsy. The number needed to test (NNT) in order to detect one case of any occult metastasis was 15. Among the included variables, a significant association was found between LN positivity and tumor centrality, with central tumors found in 61.5% of patients with positive LN (n = 8) (p < 0.01). This association stayed significant after adjusting for age, gender, smoking history, tumor size, tumor location, and PET activity (p = 0.015). Among patients with malignancy-positive LN biopsies, five (38.5%; 95% CI, 17.6%-64.6%) were upstaged to N1, and eight (61.5%; 95% CI, 35.4%-82.4%) were upstaged to N2, with NNT of 23 to detect one case of occult N2 metastasis. Subgroup analysis comparing LN-positive patients based on their N stage did not show statistically significant association with any of the variables. CONCLUSION: Based on our results and along with the existing evidence, EBUS-TBNA should be recommended as part of the routine staging in all patients with radiologic stage I NSCLC.

Characterizing Particulate Generation During Cardiopulmonary Rehabilitation Classes With Patients Wearing Procedural Masks.

BACKGROUND: The clinical benefits of cardiopulmonary rehabilitation are extensive, including improvements in health-related quality of life, emotional condition, physical function, and overall mortality. The COVID-19 pandemic continues to have a negative impact on center-based cardiopulmonary rehabilitation. Justifiable concern exists that the exercise-related increase in pulmonary ventilation within the rehabilitation classes may lead to the generation of infectious respiratory particles. RESEARCH QUESTION: Is cardiopulmonary rehabilitation while wearing a procedural mask a particle-generating procedure? STUDY DESIGN AND METHODS: Data were collected prospectively at a cardiopulmonary rehabilitation facility with all patients wearing a procedural mask. Small (0.3-4.9 µm) and large (5-10 µm) particle generation was quantified using a light-scattering particle counter. Data were analyzed by time, exertion level, and number of participants. RESULTS: A total of 24 distinct patients attended two or more of the cardiopulmonary rehabilitation classes tested. Most of the patients were men (n = 16 [67%]) and were in rehabilitation because of cardiac disease. During the cardiopulmonary rehabilitation class, small and large micrometer-size particles increased with increasing class size. In classes with four patients or more, a significant increase was found from ambient levels in both small (four patients, P < .01; and five patients, P < .01) and large (four patients, P < .01; and five patients, P < .01) particle count that peaked at about 35 to 40 min during each class. INTERPRETATION: Using an airborne particle counter, we found significant exercise-related increases in both small and large micrometer-size particle generation during cardiopulmonary rehabilitation classes, with larger class sizes (ie, more patients), despite participants wearing a procedural mask.