Translucence stereoscopy of interictal magnetoencephalographic epileptiform discharge

BACKGROUND: Exercise training is being promoted increasingly for patients with chronic obstructive pulmonary disease (COPD). Many of these patients experience exercise related arterial desaturation but the clinical importance of these hypoxaemic episodes is not known. QTc dispersion is a marker of myocardial repolarisation abnormalities and there has been much interest in its role as a non-invasive predictor of cardiac arrhythmias and sudden death. However, little is known about the dynamic effects that exercise and hypoxaemia have on QTc dispersion in patients with COPD. METHODS: 20 patients with severe COPD (FEV1 < 40% predicted) undertook two 15 minute treadmill tests at a speed calculated to produce a constant workload of 50% maximum oxygen consumption (VO2max) during which they were blindly given either air or 35% oxygen in random order. Physiological measurements taken throughout exercise included 12 lead electrocardiograms from which QTc dispersion values were calculated according to standard criteria. Nine of the patients who desaturated with exercise were studied further. A similar degree of hypoxaemia was induced at rest by giving them a titrated mixture of air and oxygen and the changes in QTc dispersion were recorded. RESULTS: 11 of the 20 patients developed significant hypoxaemia (desaturation by > or = 5% to < 90%) with exercise breathing air. There were no significant changes in QTc dispersion with either exercise or hypoxaemia. There were no significant changes in QTc dispersion when comparing those who did and did not desaturate, and those with and without a high baseline QTc dispersion values (60 ms). Induced hypoxaemia without exercise also failed to worsen QTc dispersion. CONCLUSIONS: No evidence was found to suggest that exercise, even when associated with hypoxaemia, causes myocardial repolarisation abnormalities in patients with COPD.     

The value of forced expiratory volume in 1 s in screening subjects with stable COPD for PaO2 < 7.3 kPa qualifying for long-term oxygen therapy

Guidelines on the management of chronic obstructive pulmonary disease (COPD) issued by the European Respiratory Society (ERS), British Thoracic Society (BTS), American Thoracic Society (ATS), and Department of Health for England and Wales (DoH) suggest differing values of forced expiratory volume in 1 s (FEV1) below which arterial blood gas analysis should be performed to determine the presence of severe hypoxaemia and possible long-term oxygen therapy (LTOT) requirement. This study aimed to determine the value of FEV1 at these different levels in screening for LTOT requirement defined as PaO2 < 7.3 kPa in subjects with stable COPD. Comparative measures were taken against other lung function tests of volume and diffusing capacity. A retrospective analysis of paired lung function and arterial oxygen measurements in 491 subjects was made. The positive and negative predictive values, sensitivity and specificity of FEV1 < 70% predicted (ERS), FEV1 < 50% predicted (ATS), FEV1 < 40% predicted (BTS) and FEV1 < 1.51 (DoH) were determined for fulfilling LTOT criteria (PaO2 < 7.3 kPa). The correlation between lung function variables and PaO2 was established. Logistic regression analysis was used to classify subjects with PaO2 < 7.3 kPa and PaO2 > or = 7.3 kPa. Using FEV1 to screen for LTOT requirement produced a high negative predictive value at all four suggested limits (FEV1 < 70% 100%, FEV1 < 50% 96%, FEV1 < 40% 95%, FEV1 < 1.51 97%). However, the positive predictive values were low (FEV1 < 70% 13%, FEV1 < 50% 16%, FEV1 < 40% 19%, FEV1 < 1.51 15%) as were sensitivities. No single lung function variable was a strong determinant of PaO2. FEV1 % pred (r = 0.40), FVC % pred (r = 0.34) and TLCO % pred (r = 0.27) had the strongest relationships. Logistic regression also placed FEV1 % pred and TLCO % pred as the best predictors of PaO2 < 7.3 kPa. We conclude no lung function variable correlates well with PaO2 in subjects with stable COPD. The best predictor of PaO2 < 7.3 kPa was FEV1 % pred. Whilst a low FEV1 is a poor predictor of LTOT requirement in an individual, PaO2 < 7.3 kPa is only found in subjects with a low FEV1. A high FEV1 may be used to exclude subjects from further investigation for LTOT and prevent unnecessary arterial sampling.     

Improvement in patient compliance with long-term oxygen therapy following formal assessment with training

In the Department of Respiratory Medicine, North Staffordshire Hospital, patients fulfilling the Department of Health criteria for long-term oxygen therapy (LTOT) attend a practical teaching session on the use of their oxygen concentrator before commencing therapy. In the present study, we have audited the prescribing of LTOT in all patients in three health districts in the North West Midlands reviewed between June 1992 and July 1994. They were split into two groups. The first had the assessment and training programme in the department. Patients in the control group had been prescribed LTOT from outside the department without any formal training. In both groups of patients information was collated 6 months after starting LTOT by means of a questionnaire assessing patients', understanding of both their need for oxygen and their disease process, the dangers of oxygen therapy and present smoking habit. Objective information about the usage of each concentrator was obtained from engineer reports. Thirty-six patients (eight from the trained group and 28 controls) died before evaluation at 6 months. Forty-five patients (29 male, mean age 71 years) received training and 41 control patients (24 male, mean age 72 years) were evaluated. Thirty-seven (82%) patients who had received formal training were using their concentrator for greater than 15 h compared with only 18 (44%) of the controls (P = 0.0002). Forty-two (93%) patients who had received training understood why they were using LTOT compared with only 17 (41%) in the control group (P = 0.00001). Although both groups had a similar understanding of the dangers of smoking while on oxygen therapy, six (15%) of the control group were smoking as compared to only one (2%) of the trained group (P = 0.038). One of the control patients had received significant facial burns as a direct result of smoking while on oxygen. Further efforts are required to ensure that all patients prescribed LTOT should have a formal respiratory assessment as well as training to improve compliance and to obtain maximal benefits from such therapy.     

Domiciliary oxygen therapy. Study of use in a rural area

OBJECTIVE: To assess use of long-term oxygen therapy (LTOT) in a rural community we conducted a transversal study. METHOD: Data was collected in patients' homes, and based on the total number of patients with LTOT, with reference to indication, follow-up and correct completion; two oximetries were carried out, breathing room air, and after breathing oxygen. Of the 70 patients with LTOT, 7 were considered not eligible, the prevalence was found to be: 179/100,000 inhabitants. Sixteen patients were excluded, 6 with exacerbation, and 10 who were unable to be contacted at their home address. The sample was composed of 45 patients. The most frequent diagnosis was COPD (34/45). Indication of LTOT was carried out in the hospital in 40 (89%) patients, and in the health centre in 5 (11%). RESULTS: In 22 (49%) the treatment could be considered acceptable, and only in 21 (46%), the indication of LTOT was correct. Oxygen was administered at least 15 hours/day in 42% of cases (19/45). Patients with periodical check-ups, maintained better pharmacological treatment, although there were no significant differences in the carrying out of LTOT. Using oximetry, it was shown that in 27 patients the SaO2 was lesser than or equal to 88%, and that in 23 cases (85%) administration of oxygen, corrected the saturation. Only in 11 (24%) the indication criteria and adequate administration of LTOT were carried out, as well as correction of the hypoxemia following administration of oxygen. CONCLUSIONS: The prevalence was found to be very high. The results show this form of treatment as being very badly controlled. In a rural community, the pulse oximetry is useful in the follow-up of TLOT.     

Temporal effects of prolonged hypoxaemia and reoxygenation on systemic, pulmonary and mesenteric perfusions in newborn piglets

OBJECTIVE: Temporal effects of prolonged hypoxaemia and reoxygenation, on the systemic pulmonary and mesenteric circulations in newborn piglets, were investigated. METHODS: Two groups [control (n = 5), hypoxaemic (n = 7)] of 1-3 day old anaesthetised piglets were instrumented with ultrasound flow probes placed to measure cardiac, hepatic arterial flow and portal venous flow indices, and catheters inserted for measurements of systemic and pulmonary arterial pressures. Hypoxaemia with arterial oxygen saturation 40-50% was maintained for 3 h, followed by reoxygenation with 100% inspired oxygen. RESULTS: Cardiac index was transiently elevated at 30-60 min of hypoxaemia (23% increase from baseline 158 +/- 39 ml/kg/min), along with increases in stroke volume but not heart rate. A significant decrease in systemic vascular resistance after 30 min of hypoxaemia was followed by hypotension at 180 min of hypoxaemia. Progressive pulmonary hypertension with significant vasoconstriction was found after 30 min of hypoxaemia. The hypoxaemic mesenteric vasoconstriction was transient with a 37% decrease in portal venous flow index at 15 min of hypoxaemia (29 +/- 12 vs. 46 +/- 18 ml/kg/min of baseline, p < 0.05). The hepatic arterial to total hepatic oxygen delivery ratio increased significantly during hypoxaemia. In contrast to the significant increase in systemic oxygen extraction throughout hypoxaemia, elevation in mesenteric oxygen extraction decreased after 30 min of hypoxaemia associated with modest decreases in oxygen consumption. Following reoxygenation, the pulmonary hypertension was partially reversed. Cardiac index decreased further (130 +/- 39 ml/kg/min) with reduced stroke volume, persistent systemic hypotension and decreased systemic oxygen delivery. CONCLUSIONS: We demonstrated differential temporal changes in systemic, pulmonary and mesenteric circulatory responses during prolonged hypoxaemia. Cautions need to be taken upon reoxygenation because the neonates are at risk of developing myocardial stunning, persistent pulmonary hypertension and necrotising enterocolitis.     

Pulse oximetry in severe carbon monoxide poisoning

STUDY OBJECTIVES: To evaluate the accuracy and quantitate the error of pulse oximetry measurements of arterial oxygenation in patients with severe carbon monoxide (CO) poisoning. DESIGN: Retrospective review of patient clinical records. SETTING: Regional referral center for hyperbaric oxygen therapy. PATIENTS: Thirty patients referred for treatment of acute severe CO poisoning who demonstrated carboxyhemoglobin (COHb) levels >25%, with simultaneous determinations of arterial hemoglobin oxygen saturation by pulse oximetry (SpO2) and arterial blood gas (ABG) techniques. MEASUREMENTS AND RESULTS: COHb levels and measurements of arterial oxygenation from pulse oximetry, ABG analysis, and laboratory CO oximetry were compared. SpO2 did not correlate with COHb levels. SpO2 consistently overestimated the fractional arterial oxygen saturation. The difference between arterial hemoglobin oxygen saturation (SaO2) calculated from ABG analysis and SpO2 increased with increasing COHb level. CONCLUSIONS: Presently available pulse oximeters overestimate arterial oxygenation in patients with severe CO poisoning. An elevated COHb level falsely elevates the SaO2 measurements from pulse oximetry, usually by an amount less than the COHb level, confirming a prior observation in an animal model. Accurate assessment of arterial oxygen content in patients with CO poisoning can currently be performed only by analysis of arterial blood with a laboratory CO-oximetry.     

Hypoxaemia and release of endothelin-1

BACKGROUND: Secretion of the vasoconstrictor peptide endothelin-1 from vascular endothelium is increased by various stimuli. Whether hypoxaemia affects plasma levels of endothelin-1 in humans is unknown, but this may be important in the haemodynamic response to hypoxaemia. The plasma endothelin-1 concentrations in hypoxaemic humans has therefore been measured. METHODS: Plasma levels of endothelin-1 were measured by specific radioimmunoassay in 10 control subjects at rest and following 30 minutes of acute hypoxaemia (SaO2 75-80%) induced by breathing a nitrogen/oxygen mixture, and in 10 patients with hypoxaemic cor pulmonale. RESULTS: The plasma endothelin-1 concentration in control subjects was increased from a mean (SE) of 0.90 (0.11) pmol/l at baseline to 2.34 (0.34) pmol/l during hypoxaemia. In patients with cor pulmonale the plasma endothelin-1 concentration was 2.96 (0.34) pmol/l, raised in comparison with control subjects at rest but similar to levels in controls during hypoxaemia. CONCLUSIONS: Plasma levels of endothelin-1 were increased by hypoxaemia in humans. The raised levels observed in patients with cor pulmonale may largely be attributable to the effects of hypoxaemia, although the pathophysiological significance of these observations remains to be established.     

Neuropeptide regulation of proinflammatory cytokine responses

Severe postoperative hypoxaemia during sleep may increase the risk of postoperative cardiovascular complications. We hypothesized that the severity of hypoxic episodes after surgery are related to the presence of preoperative sleep-disordered breathing (SDB). We tested this hypothesis in a multicentre study designed to elucidate the major risk factors for development of postoperative nocturnal desaturations. We performed overnight oximetry before operation and for one night between the second and fourth day after operation in 80 patients undergoing major surgery. We calculated oximetry variables such as oxygen desaturation index (ODI), defined as the number of oxygen desaturations exceeding 4% below baseline, percentage time spent at SpO2 < 90% (CT90, %) and lowest SpO2 value. After operation, although the change in ODI was not significant (P = 0.34), deterioration in CT90 and lowest SpO2 values were significant (P = 0.036 and P = 0.007, respectively). Multivariate analysis of possible risk factors for postoperative desaturations revealed that preoperative hypoxaemia and apnoea witnessed by others were highly correlated with postoperative hypoxaemia.     

Clinical predictors of hypoxaemia in Gambian children with acute lower respiratory tract infection: prospective cohort study

OBJECTIVES: To determine clinical correlates and outcome of hypoxaemia in children admitted to hospital with an acute lower respiratory tract infection. DESIGN: Prospective cohort study. SETTING: Paediatric wards of the Royal Victoria Hospital and the hospital of the Medical Research Council's hospital in Banjul, the Gambia. SUBJECTS: 1072 of 42 848 children, aged 2 to 33 months, who were enrolled in a randomised trial of a Haemophilus influenzae type b vaccine in the western region of the Gambia, and who were admitted with an acute lower respiratory tract infection to two of three hospitals. MAIN OUTCOME MEASURES: Prevalence of hypoxaemia, defined as an arterial oxygen saturation <90% recorded by pulse oximetry, and the relation between hypoxaemia and aetiological agents. RESULTS: 1072 children aged 2-33 months were enrolled. Sixty three (5.9%) had an arterial oxygen saturation <90%. A logistic regression model showed that cyanosis, a rapid respiratory rate, grunting, head nodding, an absence of a history of fever, and no spontaneous movement during examination were the best independent predictors of hypoxaemia. The presence of an inability to cry, head nodding, or a respiratory rate >/= 90 breaths/min formed the best predictors of hypoxaemia (sensitivity 70%, specificity 79%). Hypoxaemic children were five times more likely to die than non-hypoxaemic children. The presence of malaria parasitaemia had no effect on the prevalence of hypoxaemia or on its association with respiratory rate. CONCLUSION: In children with an acute lower respiratory tract infection, simple physical signs that require minimal expertise to recognise can be used to determine oxygen therapy and to aid in screening for referral. The association between hypoxaemia and death highlights the need for early recognition of the condition and the potential benefit of treatment.     

Sex hormone responses in healthy men and male patients with chronic obstructive pulmonary disease during an oral glucose load

The responses of serum testosterone, sex hormone-binding globulin (SHBG) and luteinizing hormone (LH) to an oral glucose tolerance test (OGTT) were investigated in 16 healthy subjects as well as in 11 normoxaemic and 10 hypoxaemic chronic obstructive pulmonary disease (COPD) patients. The latter group were investigated on two occasions, with and without oxygen therapy. Testosterone and apparent free testosterone concentration (AFTC) fell significantly in the healthy subjects as well as in the hypoxaemic patients on oxygen therapy (p < 0.01), whereas LH increased in all groups during the OGTT (p < 0.05). There were significantly higher SHBG levels (p < 0.01), and lower AFTC levels (p < 0.05) in the hypoxaemic group compared to the healthy subjects. In the hypoxaemic group short-term oxygen therapy increased basal AFTC significantly (p < 0.05). With oxygen therapy, the 120-min glucose levels fell significantly from 9.1 +/- 3.2 to 7.6 +/- 2.7 mmol l-1 (mean +/- SD) in the hypoxaemic group (p < 0.05). In conclusion, we have found the serum testosterone and AFTC levels to decrease after an oral glucose load in healthy subjects, together with a compensatory increase in LH. The same pattern is seen in COPD patients. The hypoxaemic patients have a reduced AFTC which is partly reversed by oxygen therapy.     

Sleep-related O2 desaturation and daytime pulmonary haemodynamics in COPD patients with mild hypoxaemia

It has been hypothesized but not firmly established that sleep-related hypoxaemia could favour the development of pulmonary hypertension in chronic obstructive pulmonary disease (COPD) patients without marked daytime hypoxaemia. We have investigated the relationships between pulmonary function data, sleep-related desaturation and daytime pulmonary haemodynamics in a group of 94 COPD patients not qualifying for conventional O2 therapy (daytime arterial oxygen tension (Pa,O2) in the range 7.4-9.2 kPa (56-69 mmHg)). Nocturnal desaturation was defined by spending > or = 30% of the recording time with a transcutaneous O2 saturation < 90%. An obstructive sleep apnoea syndrome was excluded by polysomnography. Sixty six patients were desaturators (Group 1) and 28 were nondesaturators (Group 2). There was no significant difference between Groups 1 and 2 with regard to pulmonary volumes and Pa,O2 (8.4+/-0.6 vs 8.4+/-0.4 kPa (63+/-4 vs 63+/-3 mmHg)) but arterial carbon dioxide tension (Pa,CO2) was higher in Group 1 (6.0+/-0.7 vs 53+/-0.5 kPa (45+/-5 vs 40+/-4 mmHg); p<0.0001). Mean pulmonary artery pressure (Ppa) was very similar in the two groups (2.6+/-0.7 vs 2.5+/-0.6 kPa (19+/-5 vs 19+/-4 mmHg)). No individual variable or combination of variables could predict the presence of pulmonary hypertension. It is concluded that in these patients with chronic obstructive pulmonary disease with modest daytime hypoxaemia, functional and gasometric variables (with the noticeable exception of arterial carbon dioxide tension) cannot predict the presence of nocturnal desaturation; and that mean pulmonary artery pressure is not correlated with the degree and duration of nocturnal hypoxaemia. These results do not support the hypothesis that sleep-related hypoxaemia favours the development of pulmonary hypertension.     

Accuracy of pulse oximetry in sickle cell disease

Pulmonary complications and hypoxemia are common in sickle cell disease (SCD) and may exacerbate microvascular occlusive phenomena. Thus, detecting hypoxemia is of particular importance in SCD. To assess the accuracy of pulse oximetry in the diagnosis of hypoxemia in SCD, we compared 22 pulse oximetric measurements of arterial oxygen saturation (SpO2) in adult patients with SCD and acute vasoocclusive crisis with simultaneously drawn arterial saturation (SaO2 = oxyhemoglobin divided by oxyhemoglobin plus reduced hemoglobin) measured by co-oximetry. We accepted SpO2 readings only if they were stable and characterized by strong and regular photoplethysmographic waves on the oximeter screen. To assess the position of these patients' oxyhemoglobin dissociation curves, we plotted arterial and venous oxygen saturation (SaO2 and SvO2 ) against oxygen tension. We found right-shifted oxyhemoglobin dissociation curves, with pH-corrected p50s ranging from 28 to 38 mm Hg. Pulse oximetry slightly overestimated oxyhemoglobin percentage (by an average of 3.4 percentage points), but it almost always accurately estimated SaO2 (underestimating on average by 1.1 percentage points). The error in SpO2 was never enough to classify a hypoxemic patient erroneously as normoxemic or a normoxemic patient as hypoxemic. We conclude that, as long as strong and regular photoplethysmographic waves are present, pulse oximeters can be relied upon not to misdiagnose either hypoxemia or normoxemia in SCD.     

Hypoxaemia during paediatric dental anaesthesia in the community

The object of this paper is to measure the incidence of hypoxaemia during paediatric dental anaesthesia in the community and thus support or refute the recommendations for monitoring in the Poswillo report. Fifty unpremedicated children, ASA grade 1, between the ages of 2 and 16 years undergoing general anaesthesia for teeth extraction were studied. Patients were anaesthetised with a standard anaesthetic which consisted of 30% oxygen in 70% nitrous oxide and supplemented with halothane. A pulse oximeter was used to measure the oxygen saturation continuously. A 12% incidence of hypoxaemia was recorded and a 32% incidence of a 5% fall in the oxygen saturation from the baseline. Three children became hypoxaemic during the operative period and three during the recovery period. Although the incidence of hypoxaemia in this study was significantly lower than in previous studies, the incidence suggests that careful monitoring is essential and the recommendations that have been put forward in the Poswillo report are fully justified.     

Invasive or transcutaneous measurements of oxygen saturation and blood gases? An evaluation of pulse oximetry and transcutaneous measurement of PO2 and PCO2 during rest and exercise

Arterial and transcutaneous measurements of the oxygen saturation (SO2), the partial pressure of oxygen (PO2) and the partial pressure of carbon dioxide (PCO2 were compared during rest before and after cycling, and during submaximal and maximal exercise, in 12 adult patients with cystic fibrosis. SO2 was measured non-invasively using two different pulse oximeters (Radiometer and Ohmeda, respectively) and PO2 and PCO2 were registered with a transcutaneous electrode (Radiometer). The coefficients of correlation between arterial and transcutaneous values were respectively 0.95 (Radiometer) and 0.85 (Ohmeda) for SO2, 0.77 for PO2, and 0.75 for PCO2. On average the differences between arterial and transcutaneous values were small, but varied by 3-4% (2SD) for SO2, 2.0 kPa for PO2 and 1.0 kPa for PCO2. Our results indicate that pulse oximetry is a reasonably good way of detecting severe arterial hypoxemia during work, whereas the transcutaneous measurements of PO2 and PCO2 show such large variations that this method cannot be recommended for clinical use.     

Chronic respiratory insufficiency: evaluation, evolution, prognosis

Chronic respiratory failure (CRF) is a major cause of morbidity and mortality. It is estimated that in France at least 60,000 patients exhibit severe CRF and that about 15,000 patients die each year from CRF. Chronic obstructive pulmonary disease (COPD) (chronic obstructive bronchitis, emphysema and their association) is by far the first cause of CRF (90% of the cases). The clinical picture of CRF depends on the causal disease, but exertional dyspnea is observed in almost all patients. Pulmonary function testing allows to assess whether the ventilatory defect is obstructive (COPD), restrictive or mixed. Severe CRF is usually defined by a Pa02 < 55 mmHg, in a stable state of the disease, with or without hypercapnia (PaC02 > 45 mmHg). The two major complications of CRF are acute exacerbations of the disease, with clinical and gasometric worsening, and pulmonary hypertension which may lead with time to right heart failure. Prognosis is poor in CRF since the 5 year survival rate is of 50% in COPD patients. Under long-term oxygen therapy (LTOT) the survival rate has been somewhat improved, being of 60-65% at 5 years. The best prognostic indices in CRF complicating COPD are the level of FEV1, Pa02, PaC02, the level of pulmonary artery mean pressure (PAP) and age. In COPD patients under LTOT the best prognostic indices are PAP and age.     

Hypoxemic episodes of patients in a postanesthesia care unit

The incidence, degree, and duration of acute hypoxemia were evaluated with continuous arterial hemoglobin oxygen saturation monitoring by pulse oximetry in 100 postoperative patients during 40 percent oxygen administration by aerosol face tent from postanesthetic recovery room admission to discharge. Saturations were recorded by pulse oximeters (Nellcor-N 200) with desaturations of < or = 92 percent for > or = 30 s considered significant. On recovery room admission, 15 percent of patients were experiencing episodes of desaturation. Low admission saturations correlated positively with patient age and body weight, American Society of Anesthesiologists class, patients having received general anesthesia, and with greater volumes of intraoperative intravenous fluids, particularly > 1,500 ml. Later desaturations to 86.7 +/- 4.6 percent (72 to 91 percent) at 32 +/- 54 min after admission for 5.2 +/- 12.6 min occurred in 25 percent of patients and correlated positively with peripheral surgical procedures, low oxygen saturation on admission, duration of anesthesia, and volume of intraoperative intravenous fluids. Desaturation durations were longer for female subjects and correlated positively with body weight and intravenous fluid volume. Significant arterial hemoglobin oxygen desaturations occurred despite prophylactic oxygen administration by aerosol face tent during short-term postoperative recovery room care.     

Training with supplemental oxygen in patients with COPD and hypoxaemia at peak exercise

Supplemental oxygen has acute beneficial effects on exercise performance in patients with chronic obstructive pulmonary disease (COPD). The purpose of this study was to investigate whether oxygen-supplemented training enhances the effects of training while breathing room air in patients with severe COPD. A randomized controlled trial was performed in 24 patients with severe COPD who developed hypoxaemia during incremental cycle exercise (arterial oxygen saturation (Sa,O2) <90% at peak exercise). All patients participated in an in-patient pulmonary rehabilitation programme of 10 weeks duration. They were assigned either to general exercise training while breathing room air (GET/RA group: forced expiratory volume in one second (FEV1) 38% of predicted; arterial oxygen tension (Pa,O2) 10.5 kPa at rest; Pa,O2 7.3 kPa at peak exercise), or to GET while breathing supplemental oxygen (GET/O2 group: FEV1 29% pred; Pa,O2 10.2 kPa at rest; Pa,O2 7.2 kPa at peak exercise). Sa,O2 was not allowed to fall below 90% during the training. The effects on exercise performance while breathing air and oxygen, and on quality of life were compared. Maximum workload (Wmax) significantly increased in the GET/RA group (mean (SD) 17 (15) W, p<0.01), but not in the GET/O2 group (7 (25) W). Six minute walking distance (6MWD), stair-climbing, weight-lifting exercise (all while breathing room air) and quality of life significantly increased in both groups. Acute administration of oxygen improved exercise performance before and after training. Training significantly increased Wmax, peak carbon dioxide production (V'CO2) and 6MWD while breathing oxygen in both groups. Differences between groups were not significant. Pulmonary rehabilitation improved exercise performance and quality of life in both groups. Supplementation of oxygen during the training did not add to the effects of training on room air.