Motivations for completing pulmonary rehabilitation - A qualitative analysis.

Background: Previous studies have focused on demographic factors that might predict non-completion of pulmonary rehabilitation (PR). We aimed to identify key modifiable factors that promote completion of PR. Methods: A mixed methods survey was offered to participants completing a discharge assessment following PR. Descriptive statistics and inductive thematic analysis were used to analyse the survey responses, with investigator triangulation. Results: 62 of 187 (33%) patients attending a PR discharge assessment between November 2022 and April 2023 returned the anonymised survey. Desire to improve health and wellbeing was the main reason for both initially committing to a course and for continuing with PR past transient thoughts of leaving. The positive impact of staff was the second most common reason. The enjoyment of the PR programme, being held accountable to attend classes, and the importance of other group members were other key themes identified. Conclusions: In conclusion, our findings suggest PR services need to implement strategies which ensure regular promotion and reinforcement of the health benefits of PR as well as implementation of PR modalities which best monopolise on the positive impact skilled staff have on motivating patients to complete PR.

External Validation of Toulouse-Rangueil eGFR12 Prediction Model After Living Donor Nephrectomy.

Decreased postdonation eGFR is associated with a higher risk of ESRD after living kidney donation, even when accounting for predonation characteristics. The Toulouse-Rangueil model (TRM) estimates 12 month postdonation eGFR (eGFR12) to inform counseling of candidates for living donation. The TRM was validated in several single-center European cohorts but has not been validated in US donors. We assessed the TRM in living kidney donors in the US using SRTR data 1/2000-6/2021. We compared the 2021 CKD-EPI equation eGFR12 observed estimates to the TRM eGFR12 predictions. Median (IQR) bias was -3.4 (-9.3, 3.4) mL/min/1.73 m2. Bias was higher for males vs. females (bias [IQR] -4.4 [-9.9, 1.8] vs. -2.9 [-8.8, 4.1]) and younger (31-40) vs. older donors (>50) (bias -4.9 [-10.6, 3.0] vs. -2.1 [-7.5, 4.0]). Bias was also larger for Black vs. White donors (bias (-6.7 [-12.1, -0.3], p < 0.001) vs. (-3.4 [-9.1, 3.1], p < 0.001)). Overall correlation was 0.71. In a sensitivity analysis using the 2009 CKD-EPI equation, results were generally consistent with exception to a higher overall bias (bias -4.2 [-9.8, 2.4]). The TRM overestimates postdonation renal function among US donors. Overestimation was greatest for those at higher risk for postdonation ESRD including male, Black, and younger donors. A new equation is needed to estimate postdonation renal function.

Change in gait speed and adverse outcomes in patients with idiopathic pulmonary fibrosis: A prospective cohort study.

BACKGROUND AND OBJECTIVE: Gait speed is associated with survival in individuals with idiopathic pulmonary fibrosis (IPF). The extent to which four-metre gait speed (4MGS) decline predicts adverse outcome in IPF remains unclear. We aimed to examine longitudinal 4MGS change and identify a cut-point associated with adverse outcome. METHODS: In a prospective cohort study, we recruited 132 individuals newly diagnosed with IPF and measured 4MGS change over 6 months. Death/first hospitalization at 6 months were composite outcome events. Complete data (paired 4MGS plus index event) were available in 85 participants; missing 4MGS data were addressed using multiple imputation. Receiver-Operating Curve plots identified a 4MGS change cut-point. Cox proportional-hazard regression assessed the relationship between 4MGS change and time to event. RESULTS: 4MGS declined over 6 months (mean [95% CI] change: -0.05 [-0.09 to -0.01] m/s; p = 0.02). A decline of 0.07 m/s or more in 4MGS over 6 months had better discrimination for the index event than change in 6-minute walk distance, forced vital capacity, Composite Physiologic Index or Gender Age Physiology index. Kaplan-Meier curves demonstrated a significant difference in time to event between 4MGS groups (substantial decline: >-0.07 m/s versus minor decline/improvers: ≤-0.07 m/s; p = 0.007). Those with substantial decline had an increased risk of hospitalization/death (adjusted hazard ratio [95% CI] 4.61 [1.23-15.83]). Similar results were observed in multiple imputation analysis. CONCLUSION: In newly diagnosed IPF, a substantial 4MGS decline over 6 months is associated with shorter time to hospitalization/death at 6 months. 4MGS change has potential as a surrogate endpoint for interventions aimed at modifying hospitalization/death.

An update on treatments for autosomal dominant polycystic kidney disease.

ABSTRACT: Autosomal dominant polycystic kidney disease (ADPKD) is less common than primary hypertension or diabetes but should be considered as a possible cause of end-stage renal disease, especially in young patients without comorbidities. Because of ADPKD's nonspecific symptoms, the diagnosis, treatment, and pertinent patient education may be delayed. This article describes ADPKD and its management, including tolvaptan, a new treatment with the potential to reduce or delay morbidity. However, only a subset of patients qualifies for this expensive treatment.

Digital habits of pulmonary rehabilitation service-users following the COVID-19 pandemic.

OBJECTIVE: We previously demonstrated low levels of digital literacy amongst pulmonary rehabilitation service-users prior to the COVID-19 pandemic. We aimed to identify whether the pandemic accelerated digital literacy in this population, resulting in greater acceptance of remote web-based pulmonary rehabilitation programme models. METHODS: We surveyed digital access and behaviours and pulmonary rehabilitation delivery preferences of service-users referred to pulmonary rehabilitation in 2021 (cohort 2021) and propensity score-matched them to a cohort who completed the survey in 2020 (cohort 2020). RESULTS: There were indicators that digital access and confidence were better amongst the Cohort 2021 but no difference was seen in the proportion of patients choosing remote web-based pulmonary rehabilitation as an acceptable method of receiving pulmonary rehabilitation. CONCLUSION: In an unselected cohort of service-users, remote web-based pulmonary rehabilitation was considered acceptable in only a minority of patients which has implications on healthcare commissioning and delivery of pulmonary rehabilitation.

COPD discharge bundle and pulmonary rehabilitation referral and uptake following hospitalisation for acute exacerbation of COPD.

Pulmonary rehabilitation (PR) following hospitalisations for acute exacerbation of COPD (AECOPD) is associated with improved exercise capacity and quality of life, and reduced readmissions. However, referral for, and uptake of, post-hospitalisation PR are low. In this prospective cohort study of 291 consecutive hospitalisations for AECOPD, COPD discharge bundles delivered by PR practitioners compared with non-PR practitioners were associated with increased PR referral (60% vs 12%, p<0.001; adjusted OR: 14.46, 95% CI: 5.28 to 39.57) and uptake (40% vs 32%, p=0.001; adjusted OR: 8.60, 95% CI: 2.51 to 29.50). Closer integration between hospital and PR services may increase post-hospitalisation PR referral and uptake.

Supervised pulmonary rehabilitation using minimal or specialist exercise equipment in COPD: a propensity-matched analysis.

BACKGROUND: Many trials supporting the benefits of pulmonary rehabilitation (PR) have used specialist exercise equipment, such as treadmills and cycle ergometers. However, access to specialist equipment may not be feasible in some settings. There is growing interest in delivering PR programmes with minimal, low-cost equipment, but uncertainty remains regarding their efficacy compared with programmes using specialist equipment. METHODS: Using propensity score matching, 318 consecutive patients with COPD undergoing supervised PR using minimal equipment (PR-min) were compared 1:1 with a control group of 318 patients with COPD who underwent supervised PR using specialist equipment (PR-gym). A non-inferiority analysis was performed for the primary outcome (incremental shuttle walk (ISW)) and secondary outcomes (Chronic Respiratory Disease Questionnaire (CRQ)-domain and total scores). RESULTS: Similar improvements in ISW and CRQ-domains were observed in PR-min and PR-gym groups (mean difference ISW: 3 m (95% CI -16 to 9); CRQ-total: 0.9 (95% CI -2.7 to 4.5)). The 95% CI between group differences for ISW and CRQ-total did not cross the predefined non-inferiority margins. However, completion rates were lower in PR-min compared with PR-gym (64% vs 73%; p=0.014). CONCLUSIONS: In patients with COPD, PR delivered using minimal equipment produces clinically significant benefits in exercise capacity and health-related quality of life that are non-inferior to rehabilitation delivered using specialist equipment. This study provides support for the provision of PR using minimal exercise equipment, particularly in areas where access to specialist exercise equipment is limited.

Gait speed and adverse outcomes following hospitalised exacerbation of COPD.

BACKGROUND: The 4-m gait speed (4MGS) test is a simple physical performance measure and surrogate marker of frailty that is associated with adverse outcomes in older adults. We aimed to assess the ability of 4MGS to predict prognosis in patients hospitalised with acute exacerbations of chronic obstructive pulmonary disease (AECOPD). METHODS: 213 participants hospitalised with AECOPD (52% male, mean age 72 years and mean forced expiratory volume in 1 s (FEV1) 35% predicted) were enrolled. 4MGS and baseline demographics were recorded at hospital discharge. All-cause readmission and mortality were collected for 1 year after discharge and multivariable Cox proportional hazards regressions were performed. Kaplan-Meier and competing risks analyses were conducted comparing time to all-cause readmission and mortality between 4MGS quartiles. RESULTS: 111 participants (52%) were readmitted and 35 (16%) died during the follow-up period. 4MGS was associated with all-cause readmission, with an adjusted subdistribution hazard ratio of 0.868 (95% CI 0.797-0.945; p=0.001) per 0.1 m·s-1 increase in gait speed, and with all-cause mortality, with an adjusted subdistribution hazard ratio of 0.747 (95% CI 0.622-0.898; p=0.002) per 0.1 m·s-1 increase in gait speed. Readmission and mortality models incorporating 4MGS had higher discrimination than age or FEV1 % pred alone, with areas under the receiver operator characteristic curves of 0.73 and 0.80, respectively. Kaplan-Meier and competing risks curves demonstrated that those in slower gait speed quartiles had reduced time to readmission and mortality (log-rank, both p<0.001). CONCLUSIONS: 4MGS provides a simple means of identifying at-risk patients with COPD at hospital discharge. This provides valuable information to plan post-discharge care and support.

The Effects of a Video Intervention on Posthospitalization Pulmonary Rehabilitation Uptake. A Randomized Controlled Trial.

Rationale: Pulmonary rehabilitation (PR) after hospitalizations for exacerbations of chronic obstructive pulmonary disease (COPD) improves exercise capacity and health-related quality of life and reduces readmissions. However, posthospitalization PR uptake is low. To date, no trials of interventions to increase uptake have been conducted.Objectives: To study the effect of a codesigned education video as an adjunct to usual care on posthospitalization PR uptake.Methods: The present study was an assessor- and statistician-blinded randomized controlled trial with nested, qualitative interviews of participants in the intervention group. Participants hospitalized with COPD exacerbations were assigned 1:1 to receive either usual care (COPD discharge bundle including PR information leaflet) or usual care plus the codesigned education video delivered via a handheld tablet device at discharge. Randomization used minimization to balance age, sex, FEV1 % predicted, frailty, transport availability, and previous PR experience.Measurements and Main Results: The primary outcome was PR uptake within 28 days of hospital discharge. A total of 200 patients were recruited, and 196 were randomized (51% female, median FEV1% predicted, 36 [interquartile range, 27-48]). PR uptake was 41% and 34% in the usual care and intervention groups, respectively (P = 0.37), with no differences in secondary (PR referral and completion) or safety (readmissions and death) endpoints. A total of 6 of the 15 participants interviewed could not recall receiving the video.Conclusions: A codesigned education video delivered at hospital discharge did not improve posthospitalization PR uptake, referral, or completion.

Digital habits of PR service-users: Implications for home-based interventions during the COVID-19 pandemic.

Remote models of pulmonary rehabilitation (PR) are vital with suspension of face-to-face activity during the COVID-19 pandemic. We surveyed digital access and behaviours and PR delivery preferences of current PR service users. There was significant heterogeneity in access to and confidence in using the Internet with 31% having never previously accessed the Internet, 48% confident using the Internet and 29% reporting no interest in accessing any component of PR through a Web-based app. These data have implications for the remote delivery of PR during the COVID-19 pandemic and raise questions about the current readiness of service users to adopt Web-based delivered models of PR.

Anxiety and depression in bronchiectasis: Response to pulmonary rehabilitation and minimal clinically important difference of the Hospital Anxiety and Depression Scale.

The aims of the study were to evaluate the responsiveness of Hospital Anxiety and Depression Scale-Anxiety (HADS-A) subscale and HADS-Depression (HADS-D) subscale to pulmonary rehabilitation (PR) in patients with bronchiectasis compared to a matched group of patients with chronic obstructive pulmonary disease (COPD) and provide estimates of the minimal clinically important difference (MCID) of HADS-A and HADS-D in bronchiectasis. Patients with bronchiectasis and at least mild anxiety or depression (HADS-A ≥ 8 or/and HADS-D ≥ 8), as well as a propensity score-matched control group of patients with COPD, underwent an 8-week outpatient PR programme (two supervised sessions per week). Within- and between-group changes were calculated in response to PR. Anchor- and distribution-based methods were used to estimate the MCID. HADS-A and HADS-D improved in response to PR in both patients with bronchiectasis and those with COPD (median (25th, 75th centile)/mean (95% confidence interval) change: HADS-A change: bronchiectasis -2 (-5, 0), COPD -2 (-4, 0); p = 0.43 and HADS-D change: bronchiectasis -2 (-2 to -1), COPD -2 (-3 to -2); p = 0.16). Using 26 estimates, the MCID for HADS-A and HADS-D was -2 points. HADS-A and HADS-D are responsive to PR in patients with bronchiectasis and symptoms of mood disorder, with an MCID estimate of -2 points.

Home versus outpatient pulmonary rehabilitation in COPD: a propensity-matched cohort study.

Home-based exercise has been proposed as an equivalent treatment strategy to supervised outpatient pulmonary rehabilitation (PR), but it is not known whether its implementation into clinical practice produces similar benefits to those observed in trials. We compared the real-world responses of 154 patients with COPD undergoing home-based exercise with a matched group attending supervised PR. We observed smaller improvements in exercise capacity with home-based exercise compared with PR, but similar improvements in quality of life. We propose that supervised PR remains the standard of care, with home-based exercise a less effective alternative for those unable to attend PR.

Gait speed and prognosis in patients with idiopathic pulmonary fibrosis: a prospective cohort study.

The 4-m gait speed (4MGS), a simple physical performance measure and surrogate marker of frailty, consistently predicts adverse prognosis in older adults. We hypothesised that 4MGS could predict all-cause mortality and nonelective hospitalisation in patients with idiopathic pulmonary fibrosis (IPF).4MGS and lung function were measured at baseline in 130 outpatients newly diagnosed with IPF. Survival status and nonelective hospital admissions were recorded over 1 year. We assessed the predictive value of 4MGS (as a continuous variable and as a binary variable: slow versus preserved 4MGS) by calculating hazard ratios using Cox proportional regression, adjusting for potential confounding variables. Receiver operating characteristic curves assessed discrimination between the multivariable regression models and established prognostic indices.Continuous 4MGS and slow 4MGS were independent predictors of all-cause mortality (4MGS: HR 0.03, 95% CI 0.01-0.31; p=0.004; slow 4MGS: 2.63, 95% CI 1.01-6.87; p=0.049) and hospitalisation (4MGS: HR 0.02, 95% CI 0.01-0.14; p<0.001; slow 4MGS: 2.76, 95% CI 1.16-6.58; p=0.02). Multivariable models incorporating 4MGS or slow 4MGS had better discrimination for predicting mortality than either the gender, age and lung physiology index or Composite Physiologic Index.In patients with IPF, 4MGS is an independent predictor of all-cause mortality and nonelective hospitalisation.

Pulmonary rehabilitation in bronchiectasis: a propensity-matched study.

International guidelines recommend pulmonary rehabilitation for patients with bronchiectasis, supported by small trials and data extrapolated from chronic obstructive pulmonary disease (COPD). However, it is unknown whether real-life data on completion rates and response to pulmonary rehabilitation are similar between patients with bronchiectasis and COPD.Using propensity score matching, 213 consecutive patients with bronchiectasis referred for a supervised pulmonary rehabilitation programme were matched 1:1 with a control group of 213 patients with COPD. Completion rates, change in incremental shuttle walk (ISW) distance and change in Chronic Respiratory Disease Questionnaire (CRQ) score with pulmonary rehabilitation were compared between groups.Completion rate was the same in both groups (74%). Improvements in ISW distance and most domains of the CRQ with pulmonary rehabilitation were similar between the bronchiectasis and COPD groups (ISW distance: 70 versus 63 m; CRQ-Dyspnoea: 4.8 versus 5.3; CRQ-Emotional Function: 3.5 versus 4.6; CRQ-Mastery: 2.3 versus 2.9; all p>0.20). However, improvements in CRQ-Fatigue with pulmonary rehabilitation were greater in the COPD group (bronchiectasis 2.1 versus COPD 3.3; p=0.02).In a real-life, propensity-matched control study, patients with bronchiectasis show similar completion rates and improvements in exercise and health status outcomes as patients with COPD. This supports the routine clinical provision of pulmonary rehabilitation to patients with bronchiectasis.

King's Brief Interstitial Lung Disease questionnaire: responsiveness and minimum clinically important difference.

Health status is increasingly used in clinical practice to quantify symptom burden and as a clinical trial end-point in patients with interstitial lung disease (ILD). The King's Brief Interstitial Lung Disease (KBILD) questionnaire is a brief, validated 15-item, disease-specific, health-related quality of life questionnaire that is increasingly used in clinical trials, but little data exist regarding the minimum clinically important difference (MCID). Using pulmonary rehabilitation as a model, we aimed to determine the responsiveness of KBILD and provide estimates of the MCID.KBILD scores, Chronic Respiratory Questionnaire (CRQ) scores, Medical Research Council (MRC) Dyspnoea score and incremental shuttle walk test (ISWT) distance were measured in 209 patients with ILD (105 with idiopathic pulmonary fibrosis (IPF)) before and after an outpatient pulmonary rehabilitation programme. Changes with intervention and Cohen's effect size were calculated. Anchor-based (linear regression and receiver operating characteristic plots) or distribution-based approaches (0.5 sd and standard error of measurement) were used to estimate the MCID of KBILD domain and total scores.KBILD, CRQ, MRC Dyspnoea and ISWT improved with intervention, and the effect sizes of KBILD domain and total scores ranged from 0.28 to 0.38. Using anchor-based estimates, the MCID estimates for KBILD-Psychological, KBILD-Breathlessness and activities, and KBILD-Total were 5.4, 4.4 and 3.9 points, respectively. Using distribution-based methods, the MCID estimate for KBILD-Chest symptoms was 9.8 points. The MCID estimates for KBILD in IPF patients were similar.In patients with ILD and IPF, KBILD is responsive to intervention with an estimated MCID of 3.9 points for the total score.

Gait speed and pedestrian crossings in COPD.

The assumed minimum walking speed at pedestrian crossings is 1.2 m/s. In this prospective cohort study, usual walking speed was measured over a 4 m course in 926 community-dwelling, ambulatory patients with stable COPD. Mean (SD) walking speed was 0.91 (0.24) m/s with only 10.7% walking at a speed equal or greater than 1.2 m/s. In order for 95% of this cohort to safely negotiate a pedestrian cross, traffic lights would have to assume a minimum walking speed of 0.50 m/s (2.4 times longer than current times). The current assumed normal walking speed for pedestrian crossings is inappropriate for patients with COPD.The studies were registered on clinicaltrials.gov and these data relate to the pre-results stage: NCT01649193, NCT01515709 and NCT01507415.

Permeability and diffusivity of nitric oxide in human plasma and red cells.

A simple diffusion cell was made to measure the permeability and diffusivity of Nitric Oxide in human plasma and red cells. Nitric oxide was passed through the cell containing plasma or nitrited red cells enclosed by silicone membranes. Steady state permeability (αNODNO ) was calculated from the cell dimensions and from the NO bulk flow entering and leaving the cell. The diffusion coefficient (DNO) was calculated in three ways: (i) by dividing the steady state permeability by published values for solubility (αNO ) in water at 26 °C and 37 °C (ii) by a numerical method and (iii) by an analytical method. Mean steady state permeability (95% confidence intervals) were plasma (26 °C) 5.57 × 10-11 (2.35 × 10-11-1.32 × 10-10) and (37 °C) 5.48 × 10-11 (2.13 × 10-11-1.41 × 10-10) mol cm-1 s-1 atm-1 and red cells (26 °C) 6.74 × 10-12 (1.29 × 10-12-3.53 × 10-11) and (37 °C) 3.93 × 10-11 (1.39 × 10-11-1.11.10-10) mol cm-1 s-1 atm-1. Median Diffusion Coefficients (DNO) for plasma at 37 °C ranged from 3-3.36 × 10-5 cm2 s-1 and red cells 2.41-2.94 × 10-5 cm2 s-1 depending on the method used. These values may be used for modelling NO transport in vivo in the human lung and capillary. Parameters used for modelling in vivo should be measured at 37 °C.

Phenotypic characteristics associated with slow gait speed in idiopathic pulmonary fibrosis.

BACKGROUND AND OBJECTIVE: Usual gait speed over 4 m (4MGS) is an established functional performance measure in older adults that consistently predicts adverse health outcomes, but few data exist in idiopathic pulmonary fibrosis (IPF). We assessed the reliability of 4MGS, its relationship with established outcome measures and its responsiveness to pulmonary rehabilitation. METHODS: In four prospective IPF cohorts, 4MGS inter-observer (n = 46) and test-retest (n = 46) reliability, concurrent validity (n = 65 and n = 62) and responsiveness (n = 60) were determined. The phenotypic characteristics of all patients stratified according to slow 4MGS (<0.8 m/s) were compared, including lung function parameters, HRCT of the chest, 6-min walking distance (6MWD), Medical Respiratory Council (MRC) dyspnoea score, King's Brief Interstitial Lung Disease (KBILD) questionnaire and Gender, Age and lung Physiology (GAP) prognostic index. RESULTS: Intra-class correlation coefficients for inter-observer and test-retest reliability were 0.996 and 0.983, respectively. There was a strong association between 4MGS and 6MWD (r = 0.76; P < 0.0001) and moderate correlations with MRC (r = -0.56), KBILD (r = 0.44) and GAP index (r = -0.41); all P < 0.005. 4MGS improved significantly with pulmonary rehabilitation (mean (95% CI) change: 0.16 (0.12-0.20) m/s), effect size 0.65. Patients with slow 4MGS had significantly worse exercise performance (6MWD: -167 (-220 to -133) m), dyspnoea, health status and prognosis index than those with preserved 4MGS, despite similar lung function and HRCT parameters. CONCLUSION: 4MGS is a simple, reliable, valid and responsive tool that may detect a patient phenotype with worse exercise performance, dyspnoea, health status and prognosis index in stable IPF.

Validity, responsiveness and minimum clinically important difference of the incremental shuttle walk in idiopathic pulmonary fibrosis: a prospective study.

The incremental shuttle walk (ISW) is well validated in COPD but limited psychometric data restrict its use in idiopathic pulmonary fibrosis (IPF). Study 1: 50 patients performed the ISW and 6 min walk test (6MWT). Study 2: 72 patients completed the ISW before and after pulmonary rehabilitation (PR). The ISW correlated strongly with 6MWT distance (r=0.81,p<0.0001). Mean (95% confidence interval) improvement in ISW with PR was 54 (38 to 70) m with an effect size of 0.29. Distribution-based and anchor-based minimum clinically important difference (MCID) estimates ranged from 31 to 46 m. The ISW is valid and responsive in IPF, with an anchor-based MCID estimate similar to that observed in chronic obstructive pulmonary disease. TRIAL REGISTRATION NUMBER: Pre-results; NCT02530736, NCT02436278.

Carbon Dioxide Exposure Resulting From Hood Protective Equipment Used in Joint Arthroplasty Surgery.

BACKGROUND: To protect both the surgeon and patient during procedures, hooded protection shields are used during joint arthroplasty procedures. Headache, malaise, and dizziness, consistent with increased carbon dioxide (CO2) exposure, have been anecdotally reported by surgeons using hoods. We hypothesized that increased CO2 concentrations were causing reported symptoms. METHODS: Six healthy subjects (4 men) donned hooded protection, fan at the highest setting. Arm cycle ergometry at workloads of 12 and 25 watts (W) simulated workloads encountered during arthroplasty. Inspired O2 and CO2 concentrations at the nares were continuously measured at rest, 12 W, and 25 W. At each activity level, the fan was deactivated and the times for CO2 to reach 0.5% and 1.0% were measured. RESULTS: At rest, inspired CO2 was 0.14% ± 0.04%. Exercise had significant effect on CO2 compared with rest (0.26% ± 0.08% at 12 W, P = .04; 0.31% ± 0.05% at 25 W, P = .003). Inspired CO2 concentration increased rapidly with fan deactivation, with the time for CO2 to increase to 0.5% and 1.0% after fan deactivation being rapid but variable (0.5%, 12 ± 9 seconds; 1%, 26 ± 15 seconds). Time for CO2 to return below 0.5% after fan reactivation was 20 ± 37 seconds. CONCLUSION: During simulated joint arthroplasty, CO2 remained within Occupational Safety and Health Administration (OSHA) standards with the fan at the highest setting. With fan deactivation, CO2 concentration rapidly exceeds OSHA standards.