Associations between outpatient care and later hospital admissions for patients with chronic obstructive pulmonary disease - a registry study from Norway.

BACKGROUND: Although chronic obstructive pulmonary disease (COPD) admissions put a substantial burden on hospitals, most of the patients' contacts with health services are in outpatient care. Traditionally, outpatient care has been difficult to capture in population-based samples. In this study we describe outpatient service use in COPD patients and assess associations between outpatient care (contact frequency and specific factors) and next-year COPD hospital admissions or 90-day readmissions. METHODS: Patients over 40 years of age residing in Oslo or Trondheim at the time of contact in the period 2009-2018 were identified from the Norwegian Patient Registry (in- and outpatient hospital contacts, rehabilitation) and the KUHR registry (contacts with GPs, contract specialists and physiotherapists). These were linked to the Regular General Practitioner registry (characteristics of the GP practice), long-term care data (home and institutional care, need for assistance), socioeconomic and-demographic data from Statistics Norway and the Cause of Death registry. Negative binomial models were applied to study associations between combinations of outpatient care, specific care factors and next-year COPD hospital admissions and 90-day readmissions. The sample consisted of 24,074 individuals. RESULTS: A large variation in the frequency and combination of outpatient service use for respiratory diagnoses (GP, emergency room, physiotherapy, contract specialist and outpatient hospital contacts) was apparent. GP and outpatient hospital contact frequency were strongly associated to an increased number of next-year hospital admissions (1.2-3.2 times higher by increasing GP frequency when no outpatient hospital contacts, 2.4-5 times higher in combination with outpatient hospital contacts). Adjusted for healthcare use, comorbidities and sociodemographics, outpatient care factors associated with lower numbers of next-year hospitalisations were fees indicating interaction between providers (7% reduction), spirometry with GP or specialist (7%), continuity of care with GP (15%), and GP follow-up (8%) or rehabilitation (18%) within 30 days vs. later following any current year hospitalisations. For 90-day readmissions results were less evident, and most variables were non-significant. CONCLUSION: As increased use of outpatient care was strongly associated with future hospitalisations, this further stresses the need for good communication between providers when coordinating care for COPD patients. The results indicated possible benefits of care continuity within and interaction between providers.

Feasibility and User Experience of Digital Patient Monitoring for Real-World Patients With Lung or Breast Cancer.

BACKGROUND: Digital patient monitoring (DPM) tools can facilitate early symptom management for patients with cancer through systematic symptom reporting; however, low adherence can be a challenge. We assessed patient/healthcare professional (HCP) use of DPM in routine clinical practice. MATERIALS AND METHODS: Patients with locally advanced/metastatic lung cancer or HER2-positive breast cancer received locally approved/reimbursed drugs alongside DPM, with elements tailored by F. Hoffmann-La Roche Ltd, on the Kaiku Health DPM platform. Patient access to the DPM tool was through their own devices (eg, laptops, PCs, smartphones, or tablets), via either a browser or an app on Apple iOS or Android devices. Coprimary endpoints were patient DPM tool adoption (positive threshold: 60%) and week 1-6 adherence to weekly symptom reporting (positive threshold: 70%). Secondary endpoints included experience and clinical impact. RESULTS: At data cutoff (June 9, 2022), adoption was 85% and adherence was 76%. Customer satisfaction and effort scores for patients were 76% and 82%, respectively, and 83% and 79% for HCPs. Patients spent approximately 10 minutes using the DPM tool and completed approximately 1.0 symptom questionnaires per week (completion time 1-4 minutes). HCPs spent approximately 1-3 minutes a week using the tool per patient. Median time to HCP review for alerted versus non-alerted symptom questionnaires was 19.6 versus 21.5 hours. Most patients and HCPs felt that the DPM tool covered/mostly covered symptoms experienced (71% and 75%), was educational (65% and 92%), and improved patient-HCP conversations (70% and 83%) and cancer care (51% and 71%). CONCLUSION: The DPM tool demonstrated positive adoption, adherence, and user experience for patients with lung/breast cancer, suggesting that DPM tools may benefit clinical cancer care.

Changes in cardiopulmonary exercise capacity and limitations 3-12 months after COVID-19.

RATIONALE: To describe cardiopulmonary function during exercise 12 months after hospital discharge for coronavirus disease 2019 (COVID-19), assess the change from 3 to 12 months, and compare the results with matched controls without COVID-19. METHODS: In this prospective, longitudinal, multicentre cohort study, hospitalised COVID-19 patients were examined using a cardiopulmonary exercise test (CPET) 3 and 12 months after discharge. At 3 months, 180 performed a successful CPET, and 177 did so at 12 months (mean age 59.3 years, 85 females). The COVID-19 patients were compared with controls without COVID-19 matched for age, sex, body mass index and comorbidity. Main outcome was peak oxygen uptake (V'O2  peak). RESULTS: Exercise intolerance (V'O2  peak <80% predicted) was observed in 23% of patients at 12 months, related to circulatory (28%), ventilatory (17%) and other limitations including deconditioning and dysfunctional breathing (55%). Estimated mean difference between 3 and 12 months showed significant increases in V'O2  peak % pred (5.0 percentage points (pp), 95% CI 3.1-6.9 pp; p<0.001), V'O2  peak·kg-1 % pred (3.4 pp, 95% CI 1.6-5.1 pp; p<0.001) and oxygen pulse % pred (4.6 pp, 95% CI 2.5-6.8 pp; p<0.001). V'O2  peak was 2440 mL·min-1 in COVID-19 patients compared to 2972 mL·min-1 in matched controls. CONCLUSIONS: 1 year after hospital discharge for COVID-19, the majority (77%), had normal exercise capacity. Only every fourth had exercise intolerance and in these circulatory limiting factors were more common than ventilator factors. Deconditioning was common. V'O2  peak and oxygen pulse improved significantly from 3 months.

Evaluation of the Norwegian version of the Dyspnoea-12 questionnaire in patients with COPD.

BACKGROUND: The Dyspnoea-12 (D-12) questionnaire is widely used and tested in patients with breathing difficulties. The objective of this study was to translate and undertake the first evaluation of the measurement properties of the Norwegian version of the D-12 in patients with chronic obstructive pulmonary disease (COPD) attending a 4-week inpatient pulmonary rehabilitation programme. METHODS: Confirmatory factor analysis was used to assess structural validity. Fit to the Rasch partial credit model and differential item functioning (DIF) were assessed in relation to age, sex and comorbidity. Based on a priori hypotheses, validity was assessed through comparisons with scores for the COPD Assessment Test (CAT), Hospital Anxiety and Depression Scales (HADS) and clinical variables. RESULTS: There were 203 (86%) respondents with a mean age (SD) of 65.2 (9.0) years, and 49% were female. The D-12 showed satisfactory structural validity including presence of physical and affective domains. There was acceptable fit to Rasch model including unidimensionality for the two domains, and no evidence of DIF. Correlations with scores for the CAT, HADS and clinical variables were as hypothesised and highest for domains assessing similar aspects of health. CONCLUSIONS: The Norwegian version of the D-12 showed good evidence for validity and internal consistency in this group of patients with COPD, including support for two separate domains. Further testing for these measurement properties is recommended in other Norwegian patients with dyspnoea.

Cardiopulmonary exercise capacity and limitations 3†months after COVID-19 hospitalisation.

BACKGROUND: This study aimed to describe cardiopulmonary function during exercise 3 months after hospital discharge for COVID-19 and compare groups according to dyspnoea and intensive care unit (ICU) stay. METHODS: Participants with COVID-19 discharged from five large Norwegian hospitals were consecutively invited to a multicentre, prospective cohort study. In total, 156 participants (mean age 56.2 years, 60 females) were examined with a cardiopulmonary exercise test (CPET) 3 months after discharge and compared with a reference population. Dyspnoea was assessed using the modified Medical Research Council (mMRC) dyspnoea scale. RESULTS: Peak oxygen uptake (V'O2  peak) <80% predicted was observed in 31% (n=49). Ventilatory efficiency was reduced in 15% (n=24), while breathing reserve <15% was observed in 16% (n=25). Oxygen pulse <80% predicted was found in 18% (n=28). Dyspnoea (mMRC ≥1) was reported by 47% (n=59). These participants had similar V'O2  peak (p=0.10) but lower mean±sd V'O2  peak·kg-1 % predicted compared with participants without dyspnoea (mMRC 0) (76±16% versus 89±18%; p=0.009) due to higher body mass index (p=0.03). For ICU- versus non-ICU-treated participants, mean±sd V'O2  peak % predicted was 82±15% and 90±17% (p=0.004), respectively. Ventilation, breathing reserve and ventilatory efficiency were similar between the ICU and non-ICU groups. CONCLUSIONS: One-third of participants experienced V'O2  peak <80% predicted 3 months after hospital discharge for COVID-19. Dyspnoeic participants were characterised by lower exercise capacity due to obesity and lower ventilatory efficiency. Ventilation and ventilatory efficiency were similar between ICU- and non-ICU-treated participants.

Pulmonary Rehabilitation in Patients with Pulmonary Sarcoidosis: Impact on Exercise Capacity and Fatigue.

BACKGROUND: There is limited evidence regarding the impact of multidisciplinary pulmonary rehabilitation (PR) on exercise capacity and fatigue in patients with pulmonary sarcoidosis. The aim of this study was to evaluate the impact on exercise capacity and fatigue following PR, and to examine whether baseline fatigue was related to change in peak oxygen uptake (ΔV̇O2peak). METHODS: Forty-one patients with pulmonary sarcoidosis attending a 4-week inpatient PR program were recruited to this pre-post study. Both maximal exercise capacity, defined as V̇O2peak and measured with a cardiopulmonary exercise test, and fatigue, assessed with the Fatigue Assessment Scale (score 10-50 points), were measured before and after PR. RESULTS: There was a statistically significant improvement in V̇O2peak (1.2 ± 2.3 mL/kg/min, p = 0.002), and fatigue decreased significantly (-1.7 ± 3.9 points, p = 0.009) following PR. Unadjusted linear regression analyses demonstrated that age (B = -0.076, p = 0.017) and baseline fatigue (B = 0.196, p = 0.001) were predictors for change in V̇O2peak, while in adjusted analyses (age, sex, baseline V̇O2peak, baseline fatigue, and diffusion capacity of the lung for carbon monoxide), only baseline fatigue predicted change in V̇O2peak following PR (B = 0.165, p = 0.026). CONCLUSION: A 4-week multidisciplinary PR program improves maximal exercise capacity and reduces fatigue in patients with pulmonary sarcoidosis. Baseline fatigue only partly predicted change in V̇O2peak following PR.

The acute impact of resistance training on fatigue in patients with pulmonary sarcoidosis.

Fatigue is the most prevalent symptom among patients with sarcoidosis, and skeletal muscle dysfunction is a common clinical feature, making resistance training (RT) a recommended treatment strategy. Despite lacking knowledge regarding whether high-intensity RT will aggravate fatigue, low to moderate-intensity is routinely used even if the evidence for this protocol to improve muscle strength is inconclusive. This study aimed to investigate whether one single session of high-intensity RT induces a higher increase in fatigue than one single session of moderate-intensity RT. In this randomized crossover study, 41 patients with pulmonary sarcoidosis (age: 53 ± 11 yr) were recruited. They randomly performed one single session of high-intensity RT, 4 sets × 5 repetitions maximum (5RM), and one single session of moderate-intensity RT, 2 sets × 25 RM. Fatigue was assessed with the Visual Analogue Scale (0-100 mm) immediately before (T0), immediately after (T1) and 24 hours after (T2) each exercise session. Fatigue development from T0 to T1 was significantly lower after 5RM (-3 ± 18 mm) than after 25RM (5 ± 15 mm), p = 0.004. No difference was seen from T0 to T2 between 5RM (0 ± 17 mm) and 25RM (6 ± 18 mm), p = 0.147. The high-intensity 5RM session did not induce a larger increase in fatigue than the moderate-intensity 25RM session. RT appears feasible and safe in patients with pulmonary sarcoidosis irrespective of the intensity. Thus, the long-term effects of high-intensity RT on fatigue should be explored in a RT programme of longer duration.

The effects of High- versus Moderate-Intensity Exercise on Fatigue in Sarcoidosis.

BACKGROUND: Fatigue is a common symptom in patients with sarcoidosis. Despite lacking evidence on whether high-intensity interval training (HIIT) will aggravate fatigue, moderate-intensity exercise is often recommended. This study aimed to investigate whether a single session of HIIT would affect fatigue differently from a single session of moderate-intensity continuous training (MICT). METHODS: Forty-one patients with pulmonary sarcoidosis were recruited to a cross-over study. All patients completed one treadmill session of HIIT (85% of peak heart rate (HRpeak)) and one of MICT (70% of HRpeak). Fatigue was assessed with the Visual Analogue Scale 0⁻100 mm, before (T0), after (T1), and 24 hours after (T2) each exercise session. Paired sample t-test was used to compare changes in fatigue from T0 to T1 and from T0 to T2 between HIIT and MICT. RESULTS: No statistically significant difference in fatigue levels was found between HIIT and MICT, either at T1 (3.6 (13.5) and 1.4 (13.5)) or at T2 (8.2 (17.0) and 2.1 (17.1)). CONCLUSIONS: A single session of HIIT did not affect fatigue differently than a single session of MICT. These preliminary findings support the need for further research on the long-term effect of HIIT on fatigue in patients with sarcoidosis.

A randomized cross-over trial on the direct effects of oxygen supplementation therapy using different devices on cycle endurance in hypoxemic patients with Interstitial Lung Disease.

BACKGROUND: In patients with interstitial lung disease (ILD) a cardinal feature is exercise intolerance, often associated with significant dyspnea and severe hypoxemia. Supplemental oxygen therapy may be offered during exercise. The Oxymizer is a nasal cannula with an incorporated reservoir with the potential to deliver higher oxygen doses to the patient. OBJECTIVE: The primary aim was to investigate the effect of supplemental oxygen delivered via Oxymizer compared to a conventional nasal cannula (CNC) in patients with ILD during constant work rate tests (CWRT). Secondary aim was to evaluate effects on oxygen saturation (SpO2), dyspnea and heart rate at isotime. METHODS: In this randomized crossover study 24 ILD patients established on long-term oxygen treatment were included. Patients performed four cycling CWRT at 70% of their peak work rate; twice with the Oxymizer and twice with the CNC. RESULTS: Twenty-one patients finished all CWRTs (age 60 ± 10.9 years, VC 55.4 ± 23.0%predicted). Cycle endurance time was significantly higher while using the Oxymizer compared to CNC (718 ± 485 vs. 680 ± 579 seconds, p = 0.02), and SpO2 at isotime was significantly higher while using the Oxymizer (85.5 ± 6.7 vs. 82.8± 7.2, p = 0.01). Fifteen of the 21 (71%) patients cycled longer with the Oxymizer. There were no significant differences for dyspnea and heart rate. CONCLUSIONS: Supplemental oxygen provided by the Oxymizer significantly, but modestly, improved cycle endurance time and SpO2 at isotime in ILD patients compared to CNC.

An evaluation of the short physical performance battery following pulmonary rehabilitation in patients with chronic obstructive pulmonary disease.

OBJECTIVE: There is a need for simple tools to evaluate physical performance in patients with COPD before and after pulmonary rehabilitation. The aims of this study were to evaluate changes in short physical performance battery (SPPB)-scores in patients with COPD after a 4-week pulmonary rehabilitation program; explore possible relationships between SPPB-scores and exercise capacity (6-min walk distance), dyspnea (modified Medical Research Council's dyspnea scale), disease-specific quality of life (COPD assessment test), and pulmonary function (predicted forced expiratory volume in one second) at baseline; and explore if changes in SPPB-scores are related to changes in exercise capacity, dyspnea, and disease-specific quality of life following pulmonary rehabilitation. RESULTS: Forty-five patients with COPD were included in the final analysis. SPPB-scores improved following pulmonary rehabilitation (mean change: 1.2 ± 1.7 points, p < 0.001). There were moderate correlations between SPPB-scores and exercise capacity (r = 0.50, p < 0.001) and dyspnea (r = - 0.45, p = 0.003) at baseline, but not with pulmonary function or disease-specific quality of life. Changes in SPPB-scores were not associated with changes in exercise capacity or dyspnea scores. The SPPB may be a useful tool for evaluating physical performance in COPD Trial registration ClinicalTrials.gov NCT02314338, December 11, 2014.

COPD and air travel: does hypoxia-altitude simulation testing predict in-flight respiratory symptoms?

The reduced pressure in an aircraft cabin may cause significant hypoxaemia and respiratory symptoms in patients with chronic obstructive pulmonary disease (COPD). The current study evaluated whether there is a relationship between hypoxaemia obtained during hypoxia-altitude simulation testing (HAST), simulating an altitude of 2438 m, and the reporting of respiratory symptoms during air travel. 82 patients with moderate to very severe COPD answered an air travel questionnaire. Arterial oxygen tensions during HAST (PaO2HAST) in subjects with and without in-flight respiratory symptoms were compared. The same questionnaire was answered within 1 year after the HAST. Mean ± sd PaO2HAST was 6.3 ± 0.6 kPa and 62 (76%) of the patients had PaO2HAST <6.6 kPa. 38 (46%) patients had experienced respiratory symptoms during air travel. There was no difference in PaO2HAST in those with and those without in-flight respiratory symptoms (6.3 ± 0.7 kPa versus 6.3 ± 0.6 kPa, respectively; p=0.926). 54 (66%) patients travelled by air after the HAST, and patients equipped with supplemental oxygen (n = 23, 43%) reported less respiratory symptoms when flying with than those without such treatment (four (17%) versus 11 (48%) patients; p=0.039). In conclusion, no difference in PaO2HAST was found between COPD patients with and without respiratory symptoms during air travel.

Air travel and chronic obstructive pulmonary disease: a new algorithm for pre-flight evaluation.

BACKGROUND: The reduced pressure in the aircraft cabin may cause significant hypoxaemia and respiratory distress in patients with chronic obstructive pulmonary disease (COPD). Simple and reliable methods for predicting the need for supplemental oxygen during air travel have been requested. OBJECTIVE: To construct a pre-flight evaluation algorithm for patients with COPD. METHODS: In this prospective, cross-sectional study of 100 patients with COPD referred to hypoxia-altitude simulation test (HAST), sea level pulse oximetry at rest (SpO(2 SL)) and exercise desaturation (SpO(2 6MWT)) were used to evaluate whether the patient is fit to fly without further assessment, needs further evaluation with HAST or should receive in-flight supplemental oxygen without further evaluation. HAST was used as the reference method. RESULTS: An algorithm was constructed using a combination of SpO(2 SL) and SpO(2 6MWT). Categories for SpO(2 SL) were >95%, 92-95% and <92%, the cut-off value for SpO(2 6MWT) was calculated as 84%. Arterial oxygen pressure (PaO(2 HAST)) <6.6 kPa was the criterion for recommending supplemental oxygen. This algorithm had a sensitivity of 100% and a specificity of 80% when tested prospectively on an independent sample of patients with COPD (n=50). Patients with SpO(2 SL) >95% combined with SpO(2 6MWT) ≥84% may travel by air without further assessment. In-flight supplemental oxygen is recommended if SpO(2 SL)=92-95% combined with SpO(2 6MWT) <84% or if SpO(2 SL) <92%. Otherwise, HAST should be performed. CONCLUSIONS: The presented algorithm is simple and appears to be a reliable tool for pre-flight evaluation of patients with COPD.

Arterial oxygen pressure following whole-body vibration at altitude.

INTRODUCTION: Most helicopter operations are carried out at altitudes below 10,000 ft. At these altitudes, the risk of the crew experiencing hypoxia is low. For that reason, supplementary oxygen is not standard equipment on board most helicopters. Due to developments in military missions, high-altitude operations have become more frequent-as have the chances of the crew experiencing hypoxia. Helicopter crews are subjected to a higher load of whole-body vibration compared to fixed-wing aircraft crews. Whole-body vibration increases muscle work, with increased oxygen consumption as a result. We hypothesized that whole-body vibration, as experienced by helicopter crews, causes additional lowering of arterial oxygen levels under hypoxic conditions. METHODS: Data were collected from 10 subjects. They were all exposed to six different pressure altitudes in a hypobaric chamber, ranging from 1000 ft to 16,000 ft (approximately 305 m to approximately 4877 m). Arterial blood samples were drawn on two occasions at each altitude: after 14 min of rest and followed by 15 min of whole-body vibration (17 Hz, at 1.1 m x s(-2) in the z-axis) at each altitude. RESULTS: There was no significant effect of whole-body vibration on arterial oxygen pressure at altitudes up to 16,000 ft (approximately 4877 m), nor was there any effect on ventilation, seen as changes in arterial pressure of CO2. DISCUSSION: We contribute the lack of effect to the low vibration intensity used in this study. Since this vibration intensity was higher than experienced by helicopter crews during flight, we conclude that whole-body vibration does not contribute to hypoxia during high-altitude operations in helicopters.

High prevalence of respiratory symptoms during air travel in patients with COPD.

OBJECTIVE: The reduced pressure in aircraft cabins may cause severe hypoxemia and respiratory distress in patients with chronic obstructive pulmonary disease (COPD). The primary objective of this study was to determine the prevalence of in-flight symptoms in COPD patients and non-COPD subjects, and evaluate associations between these symptoms and pre-flight variables. METHODS: In a cross-sectional study of 391 COPD patients and 184 non-COPD subjects, we recorded lung function, blood gas values, exercise capacity, air travel habits and in-flight symptoms. RESULTS: Fifty-four percent of the COPD patients had travelled by air the last two years. Hypoxia-related symptoms during air travel were experienced in 25% of the COPD patients and 9% of the non-COPD subjects (p < 0.001). After adjusting for smoking status, age and gender, the odds ratio for COPD patients to experience dyspnea or air hunger was 6.6 (95% CI 2.5-17.3, p < 0.001) compared to non-COPD subjects. In the COPD patients, in-flight dyspnea or air hunger was strongly associated with pre-flight score on the Medical Research Council (MRC) Dyspnea scale (p < 0.001). CONCLUSION: COPD patients had significantly increased risk of in-flight dyspnea or air hunger compared to non-COPD subjects. In COPD patients these symptoms were strongly associated with pre-flight MRC Dyspnea score.

COPD and air travel: oxygen equipment and preflight titration of supplemental oxygen.

BACKGROUND: Patients with COPD may need supplemental oxygen during air travel to avoid development of severe hypoxemia. The current study evaluated whether the hypoxia-altitude simulation test (HAST), in which patients breathe 15.1% oxygen simulating aircraft conditions, can be used to establish the optimal dose of supplemental oxygen. Also, the various types of oxygen-delivery equipment allowed for air travel were compared. METHODS: In a randomized crossover trial, 16 patients with COPD were exposed to alveolar hypoxia: in a hypobaric chamber (HC) at 2,438 m (8,000 ft) and with a HAST. During both tests, supplemental oxygen was given by nasal cannula (NC) with (1) continuous flow, (2) an oxygen-conserving device, and (3) a portable oxygen concentrator (POC). RESULTS: PaO(2) kPa (mm Hg) while in the HC and during the HAST with supplemental oxygen at 2 L/min (pulse setting 2) on devices 1 to 3 was (1) 8.6 ± 1.0 (65 ± 8) vs 12.5 ± 2.4 (94 ± 18) (P < .001), (2) 8.6 ± 1.6 (64 ± 12) vs 9.7 ± 1.5 (73 ± 11) (P < .001), and (3) 7.7 ± 0.9 (58 ± 7) vs 8.2 ± 1.1 (62 ± 8) (P= .003), respectively. CONCLUSIONS: The HAST may be used to identify patients needing supplemental oxygen during air travel. However, oxygen titration using an NC during a HAST causes accumulation of oxygen within the facemask and underestimates the oxygen dose required. When comparing the various types of oxygen-delivery equipment in an HC at 2,438 m (8,000 ft), compressed gaseous oxygen with continuous flow or with an oxygen-conserving device resulted in the same PaO(2), whereas a POC showed significantly lower PaO(2) values. TRIAL REGISTRY: ClinicalTrials.gov; No.: Identifier: NCT01019538; URL: clinicaltrials.gov.

Pulse oximetry in the preflight evaluation of patients with chronic obstructive pulmonary disease.

INTRODUCTION: In a British Thoracic Society (BTS) statement on preflight evaluation of patients with respiratory disease, sea level pulse oximetry (Spo2sl) is recommended as an initial assessment. The present study aimed to evaluate if the BTS algorithm can be used to identify chronic obstructive pulmonary disease (COPD) patients in need of supplemental oxygen during air travel, i.e. patients with an in-flight PaO2 < 6.6 kPa (50 mmHg). METHODS: There were 100 COPD patients allocated to groups according to the BTS algorithm: Spo2sl > 95%, Spo2sl 92-95% without additional risk factors; Spo2sl 92-95% with additional risk factors; Spo2sl < 92%; and patients using domiciliary oxygen. Pulse oximetry, arterial blood gases, and an hypoxia-altitude simulation test (HAST) to simulate a cabin altitude of 2438 m (8000 ft), were performed. RESULTS: The percentage of patients in the various groups dropping below 6.6 kPa during HAST were: Spo2sl > 95%: 30%; Spo2sl 92-95% without additional risk factors: 67%; Spo2sl 92-95% with additional risk factors: 70%; Spo2sl < 92%: 83%; and patients using domiciliary oxygen: 81%. In patients dropping below P(a)o(2) 6.6 kPa, supplemental oxygen of median 1 L x min(-1) was needed to exceed this limit. DISCUSSION: If in-flight P(a)o(2) > or = 6.6 kPa is regarded as a strict requirement, the use of pulse oximetry as an initial assessment in the preflight evaluation of COPD patients, as suggested by the BTS, might not discriminate adequately between patients who fulfill the indications for supplemental oxygen during air travel, and patients who can travel without such treatment.