***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND Oxygen conserving devices may lead to substantial increases in the duration of oxygen provided . A study was undertaken to compare the performance of a pulsed dose oxygen delivery ( PDOD ) system with continuous flow oxygen or air during a maximal walking test . METHODS Fourteen patients with chronic obstructive pulmonary disease ( COPD ) and arterial oxygen desaturation on exercise ( mean ( SD ) forced expiratory volume in one second ( FEV1 ) 0.83 ( 0.28 ) l , arterial oxygen pressure ( Pao 2 ) 8.38 ( 1.24 ) kPa , arterial carbon dioxide pressure ( Paco 2 ) 5.95 ( 0.86 ) kPa ) were r and omised to perform a walking test using air administered via a cylinder or continuous flow oxygen at 2 l/min or by a PDOD system . RESULTS There was no significant difference in the mean arterial oxygen saturation ( Sao 2 ) using the PDOD system or with continuous flow oxygen ( p = 0.33 ) . Patients showed greatest desaturation whilst walking with the air cylinder ( Sao 2 79.2 (8.59)% ) which was significantly different from the desaturation with both continuous flow oxygen ( 87.6 (5.85)% , p = 0.001 ) and PDOD ( 85.6 (7.36)% , p = 0.004 ) . There was no significant difference between the distance walked using oxygen delivered at 2 l/min by continuous flow or via the PDOD ( p = 0.72 ; CI 0.34 to 1.08 ) . The mean ( SD ) distance walked on continuous flow oxygen ( 203.6 ( 106.1 ) m ) and PDOD ( 207.9 ( 109.8 ) m ) was significantly greater than the distance walked with the air cylinder ( 188.6 ( 110.02 ) m ) ; ( 1.12 fold increase in distance , CI 1.01 to 1.23 , p = 0.02 , and 1.14 fold increase in distance , CI 1.01 to 1.28 , p = 0.03 , respectively ) . CONCLUSIONS These findings suggest that the pulsed dose oxygen conserving device was as effective as continuous flow oxygen in maintaining arterial oxygen saturation and that the use of this device was associated with similar improvements in exercise tolerance to patients taking continuous flow oxygen therapy BACKGROUND : Correction of exercise hypoxemia in advanced lung diseases is crucial and often challenging . However , oxygen-conserving devices have been introduced in the market with limited evidence of effectiveness . In the present study the efficacy of 2 oxygen-conserving devices , a pulse dem and oxygen delivery ( DOD ) system and pendant reservoir cannula ( PRC ) , were evaluated in subjects with COPD and interstitial lung disease ( ILD ) . METHODS : A cross-sectional , crossover study included 28 COPD and 31 ILD subjects with oxygen desaturation on the 6-min walk test ( average SpO2 < 88 % ) . Each subject underwent 3 walk tests with DOD , PRC , and continuous oxygen flow by st and ard nasal cannula ( CFNC ) , in r and om order , taking average SpO2 ≥ 90 % as the resaturation criterion . RESULTS : Exercise desaturation was corrected in 79 % , 79 % , and 86 % of COPD subjects with CFNC , DOD , and PRC , respectively , and in 77 % , 61 % , and 81 % of ILD subjects with CFNC , DOD , and PRC , respectively . When compared to CFNC , the oxygen-conserving devices showed similar efficacy , except a lower performance for the DOD in the ILD subjects ( P = .01 ) . CONCLUSIONS : Although these oxygen-conserving devices corrected exercise hypoxemia in most COPD and ILD subjects , correction was not achieved in about 20 % of the severe COPD subjects , regardless of the device , and in nearly 40 % of the ILD subjects with the DOD device . These findings underscore that individualized adjustment of oxygen flow is needed for optimal correction of exercise hypoxemia , especially with a DOD in an ILD patient . ( Clinical Trials.gov NCT01086891 ) BACKGROUND : Provision of ambulatory oxygen using an intermittent pulsed flow regulated by a dem and oxygen delivery system ( DODS ) greatly increases the limited supply time of st and ard portable gaseous cylinders . The efficacy of such a system has not previously been studied during submaximal exercise in subjects with severe chronic obstructive pulmonary disease ( COPD ) in whom desaturation is likely to be great and where usage is often most appropriate . METHODS : Fifteen subjects with severe COPD and oxygen desaturation underwent six minute walk tests performed in r and om order to compare the efficacy of a dem and oxygen delivery system ( DODS ) with continuous flow oxygen .  Walk distance , breathlessness , oxygen saturation , resting time , and recovery time ( objective and subjective ) were recorded and compared for each walk . RESULTS : Breathing continuous oxygen compared with baseline air breathing improved mean walk distance ( 295 m versus 271 m ) and recovery time ( 47 seconds versus 112 seconds ) , whilst the lowest recorded saturation ( 81 % versus 74 % ) and time desaturated below 90 % ( 201 seconds versus 299 seconds ) were reduced . When the DODS was compared with air breathing only the walk distance changed ( 283 m versus 271 m ) . A comparison of the DODS with continuous oxygen breathing showed the DODS to be less effective at oxygenating subjects with inferior lowest saturation ( 78 % versus 81 % ) , time spent below 90 % ( 284 seconds versus 201 seconds ) , time to objective recovery ( 83 seconds versus 47 seconds ) , and walk distance ( 283 m versus 295 m ) . CONCLUSIONS : Neither of the delivery systems was able to prevent desaturation in these subjects . The use of continuous flow oxygen , however , was accompanied by improvements in oxygenation , walk distance , and recovery time compared with air breathing . The DODS produced only a small increase in walk distance without elevation of oxygen saturation , but was inferior to continuous flow oxygen in most of the measured variables when compared directly OBJECTIVES The aim of this study was to assess the performance of four dem and oxygen delivery systems ( DODS ) in improving oxygenation and effort tolerance , at rest and during exercise , in chronic obstructive pulmonary disease ( COPD ) patients . MATERIAL S AND METHODS Thirteen COPD patients were prospect ively included . Four DODS ( Oxiclip , Versatile , Venture and Impulse ) were compared with continuous-flow oxygen ( CFO ) . Nine of these patients performed 6-min walking tests on room air and on 3 l/min oxygen by DODS and CFO ; Oxygen saturation , walking distance and the Borg dyspnea score were recorded . RESULTS With all four DODS devices arterial oxygenation was improved with lower oxygen flow rates than with CFO . Oxygen economy was best with Impulse , but at a cost of less satisfactory oxygenation . Exercise desaturation was similar with CFO , Oxiclip , Venture , and Impulse but significantly higher with Versatile ( P < 0.05 ) . Borg dyspnea scores were similar with CFO , Oxiclip , Venture , and Versatile but worse with Impulse ( P < 0.05 ) . There was no significant difference in walking distances . CONCLUSIONS All four DODS improved oxygen saturation and saved oxygen . However , performance was better with the two devices ( Oxiclip and Venture ) that deliver a bolus of oxygen at inspiration onset Abstract . Objective : Pulse oximetry ( SpO2 ) is a st and ard monitoring device in intensive care units ( ICUs ) , currently used to guide therapeutic interventions . Few studies have evaluated the accuracy of SpO2 in critically ill patients . Our objective was to compare pulse oximetry with arterial oxygen saturation ( SaO2 ) in such patients , and to examine the effect of several factors on this relationship . Design : Observational prospect i ve study . Setting : A 26-bed medical ICU in a university hospital . Patients : One hundred two consecutive patients admitted to the ICU in whom one or serial arterial blood gas analyses ( ABGs ) were performed and a reliable pulse oximeter signal was present . Interventions : For each ABG , we collected  SaO2 , SpO2 , the type of pulse oximeter , the mode of ventilation and requirement for vasoactive drugs .  Measurements and results : Three hundred twenty-three data points were collected . The mean difference between SpO2 and SaO2 was –0.02 % and st and ard deviation of the differences was 2.1 % . From one sample to another , the fluctuations in SpO2 to arterial saturation difference indicated that SaO2 could not be reliably predicted from SpO2 after a single ABG . Subgroup analysis showed that the accuracy of SpO2 appeared to be influenced by the type of oximeter , the presence of hypoxemia and the requirement for vasoactive drugs . Finally , high SpO2 thresholds were necessary to detect significant hypoxemia with good sensitivity . Conclusion : Large SpO2 to SaO2 differences may occur in critically ill patients with poor reproducibility of SpO2 . A SpO2 above 94 % appears necessary to ensure a SaO2 of 90 % To maintain mobility in patients with chronic hypoxemia who are under long-term oxygen therapy , portable oxygen systems are available . They have the disadvantage of a short range . To prolong the range and to reduce the cost of oxygen treatment , dem and oxygen delivery systems ( DODS ) are used . Aim of the study was to compare three DODS ( DOC-2000 [ D ] , TransTracheal Inc. ; Oxytron [ O ] , Weinmann ; Pulsair [ P ] , DeVilbiss , Sunrise Medical ) with continuous oxygen delivery . 17 patients ( age 67.82 + /- 9.46 years ; FEV1 1.23 + /- 0.69 l ; PaO2 48.8 + /- 6.7 mm Hg ) were studied . The continuous flow oxygen ( CONT ) and the DODS were applied to the patients for 30 minutes each in r and om sequence with an airflow of 2 l/min . After 15 and 30 minutes arterial blood gas analysis was done . Oxygen saturation was recorded continuously by pulseoximetry . After 15 minutes no significant differences in PaO2 were found between CONT and DODS . After 30 minutes no significant difference in PaO2 was found in CONT as compared to P. Significant lower PaO2 values were found for O and D as compared to CONT ( p < 0.01 ) . With P the range of a portable oxygen source was increased by 161.5 percent , with O by 172 percent , with D the range was increased by only 17.2 percent . Prolongation of range of a portable oxygen source can be achieved by means of DODS without a decrease of PaO2 and thus without loss of quality of the oxygen treatment . However , there are differences in efficacy between the DODS AIM Dem and oxygen delivery systems ( DODSs ) were developed to secure the mobility of patients requiring oxygen therapy . The aim of the present study was to compare the efficacy of two currently available DODS with continuous oxygen administration ( CONT ) . PATIENTS Thirteen patients with COPD ( mean [ + /- SD ] FEV1 , 28 + /- 5.2 % predicted ; mean P(O2 ) , 56.4 + /- 8.1 mm Hg [ breathing room air ] ) . INTERVENTION Treatment for 30 min with CONT at a flow rate of 2 L/min , with the DODSs Oxytron 3 ( Weinmann ; Hamburg , Germany ) or DeVilbiss EX 3000 ( Somerset , PA ) in r and om sequence . Arterialized blood sample s were obtained from a hyperaemized ear lobe after 15 and 30 min . RESULTS After 15 min , no significant differences in P(O2 ) or arterial oxygen saturation ( Sa(O2 ) ) were observed . In comparison with CONT ( mean P(O2 ) , 70.5 + /- 10.4 mm Hg ; mean Sa(O2 ) , 94.8 + /- 2.13 % ) , oxygenation with the  Oxytron 3 ( mean P(O2 ) , 66.3 + /- 10.3 mm Hg ; mean Sa(O2 ) , 93.5 + /- 2.6 % ) was significantly less after 30 min when measured independently by blood gas analysis and pulse oximetry . The DeVilbiss EX 3000 ( mean P(O2 ) , 69.1 + /- 12.0 mm Hg ; mean Sa(O2 ) , 94.5 + /- 3.2 % ) and CONT showed no differences . CONCLUSIONS P(O2 ) did not reach equilibrium after 15 min of treatment with the DODSs . The titration of a patient to a DODS is recommended , since simply accepting the manufacturer 's information on oxygen equivalent does not guarantee an adequate supply of oxygen A total of 264 eligible patients with advanced ovarian cancer were r and omised to single or triple agent cytotoxic therapy ; 261 were available for analysis . The treatments were continuous oral cyclophosphamide ( arm S ) , and a combination of oral cyclophosphamide , hexamethylmelamine and methotrexate on a pulsed basis ( arm T ) . Mortality attributed to cancer was slightly lower on arm T ( p = 0.06 ) , but this was offset by the greater toxicity of this regimen , and overall survival and activity index were similar on the 
    Output:
    
These findings from a limited number of studies suggest oxygen delivery via DODS or CONT confers similar effects in terms of SpO2 % or exercise performance in patients with COPD .