Usefulness of the Medical Research Council (MRC) dyspnoea scale as a measure of disability in patients with chronic obstructive pulmonary disease

BACKGROUND

Methods of classifying chronic obstructive pulmonary disease (COPD) depend largely upon spirometric measurements but disability is only weakly related to measurements of lung function. With the increased use of pulmonary rehabilitation, a need has been identified for a simple and standardised method of categorising disability in COPD. This study examined the validity of the Medical Research Council (MRC) dyspnoea scale for this purpose.

METHODS

One hundred patients with COPD were recruited from an outpatient pulmonary rehabilitation programme. Assessments included the MRC dyspnoea scale, spirometric tests, blood gas tensions, a shuttle walking test, and Borg scores for perceived breathlessness before and after exercise. Health status was assessed using the St George's Respiratory Questionnaire (SGRQ) and Chronic Respiratory Questionnaire (CRQ). The Nottingham Extended Activities of Daily Living (EADL) score and Hospital Anxiety and Depression (HAD) score were also measured.

RESULTS

Of the patients studied, 32 were classified as having MRC grade 3 dyspnoea, 34 MRC grade 4 dyspnoea, and 34 MRC grade 5 dyspnoea. Patients with MRC grades 1 and 2 dyspnoea were not included in the study. There was a significant association between MRC grade and shuttle distance, SGRQ and CRQ scores, mood state and EADL. Forced expiratory volume in one second (FEV1) was not associated with MRC grade. Multiple logistic regression showed that the determinants of disability appeared to vary with the level of disability. Between MRC grades 3 and 4 the significant covariates were exercise performance, SGRQ and depression score, whilst between grades 4 and 5 exercise performance and age were the major determinants.

CONCLUSIONS

The MRC dyspnoea scale is a simple and valid method of categorising patients with COPD in terms of their disability that could be used to complement FEV1 in the classification of COPD severity.

Effect of temperature on lung function and symptoms in chronic obstructive pulmonary disease

The present study investigated whether falls in environmental temperature increase morbidity from chronic obstructive pulmonary disease (COPD). Daily lung function and symptom data were collected over 12 months from 76 COPD patients living in East London and related to outdoor and bedroom temperature. Questionnaires were administered which asked primarily about the nature of night-time heating. A fall in outdoor or bedroom temperature was associated with increased frequency of exacerbation, and decline in lung function, irrespective of whether periods of exacerbation were excluded. Forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) fell markedly by a median of 45 mL (95% percentile range: -113-229 mL) and 74 mL (-454-991 mL), respectively, between the warmest and coolest week of the study. The questionnaire revealed that 10% had bedrooms <13 degrees C for 25% of the year, possibly because only 21% heated their bedrooms and 48% kept their windows open in November. Temperature-related reduction in lung function, and increase in exacerbations may contribute to the high level of cold-related morbidity from chronic obstructive pulmonary disease.

Effect of temperature on lung function and symptoms in chronic obstructive pulmonary disease

The present study investigated whether falls in environmental temperature increase morbidity from chronic obstructive pulmonary disease (COPD). Daily lung function and symptom data were collected over 12 months from 76 COPD patients living in East London and related to outdoor and bedroom temperature. Questionnaires were administered which asked primarily about the nature of night-time heating. A fall in outdoor or bedroom temperature was associated with increased frequency of exacerbation, and decline in lung function, irrespective of whether periods of exacerbation were excluded. Forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) fell markedly by a median of 45 mL (95% percentile range: -113-229 mL) and 74 mL (-454-991 mL), respectively, between the warmest and coolest week of the study. The questionnaire revealed that 10% had bedrooms <13 degrees C for 25% of the year, possibly because only 21% heated their bedrooms and 48% kept their windows open in November. Temperature-related reduction in lung function, and increase in exacerbations may contribute to the high level of cold-related morbidity from chronic obstructive pulmonary disease.

Evaluation of pulsed dose oxygen delivery during exercise in patients with severe chronic obstructive pulmonary disease

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) 1, arterial oxygen pressure (PaO2) 8.38 (1.24) kPa, arterial carbon dioxide pressure (PaCO2) 5.95 (0.86) kPa) were randomised 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 (SaO2) using the PDOD system or with continuous flow oxygen (p = 0.33). Patients showed greatest desaturation whilst walking with the air cylinder (SaO2 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.

An observational study of inhaled corticosteroid withdrawal in stable chronic obstructive pulmonary disease. ISOLDE Study Group

Withdrawal of inhaled corticosteroids is known to worsen disease control in bronchial asthma but similar data are lacking in chronic obstructive pulmonary disease (COPD). We hypothesized that clinical exacerbations requiring treatment would occur more often in patients whose inhaled corticosteroids were stopped than in other patients not treated with these agents. We studied 272 patients in mean age 65 (SD 0.8) years, mean FEV1 42.8 (SD 12.6)% predicted, entering the run-in phase of the Inhaled Steroids in Obstructive Lung Disease (ISOLDE) trial. All had been clinically stable for at least 6 weeks and there were no differences in the degree of bronchodilator reversibility, baseline lung function or pack-years of smoking between the 160 patients receiving inhaled corticosteroids and those not so treated. Inhaled corticosteroids were withdrawn in the first week of the study and during the remaining 7 weeks of the study 38% of those previously treated with these drugs had an exacerbation compared to 6% of the chronically untreated group. Patients receiving inhaled corticosteroids reported a longer duration of symptoms but neither this or any other recorded variable predicted the risk of exacerbation. These data suggest that abrupt withdrawal of inhaled corticosteroids should be monitored carefully even in patients with apparently irreversible COPD.

Comparison of spontaneous and induced sputum for investigation of airway inflammation in chronic obstructive pulmonary disease

BACKGROUND

Although sputum induction is used as a technique to investigate lower airway inflammation in asthmatic subjects, advantages over spontaneous sputum in patients with chronic obstructive pulmonary disease (COPD) have not been investigated.

METHODS

Samples of spontaneous sputum and sputum induced with 3% hypertonic saline for 14 minutes were collected from 27 patients with chronic obstructive pulmonary disease (COPD) who usually produced spontaneous sputum. Spirometric indices and oxygen saturation (Sao2) were measured at seven minute intervals. The spontaneous, seven and 14 minute sputum samples were analysed for total and differential cell counts, cell viability, and interleukin 8 levels.

RESULTS

Analysis of the sputum revealed that median cell viability was higher in the seven minute (62.8%; p = 0.004) and 14 minute (65%; p = 0.001) induced sputum samples than in spontaneous sputum (41.2%). There was no significant difference in total and differential cell counts or in interleukin 8 levels between spontaneous and induced sputum. During the sputum induction procedure the mean (SD) fall in forced expiratory volume in one second (FEV1) was 0.098 (0.111) 1 (p < 0.001) and in forced vital capacity (FVC) was 0.247 (0.233) 1 (p < 0.001). There was a small but significant fall in Sao2 during sputum induction (p = 0.03).

CONCLUSIONS

Induced sputum contains a higher proportion of viable cells than spontaneous sputum. There are no significant differences between the sputum samples obtained at seven minutes and at 14 minutes of hypertonic saline nebulisation. Sputum induction is safe and well tolerated in patients with COPD.

Randomized controlled trial of pulmonary rehabilitation in severe chronic obstructive pulmonary disease patients, stratified with the MRC dyspnoea scale

This study tested the hypothesis that severity of respiratory disability may affect the outcome of pulmonary rehabilitation. In this randomized, controlled study, 126 patients with chronic obstructive pulmonary disease (COPD) were stratified for dyspnoea using the Medical Research Council (MRC) dyspnoea score into MRC3/4 (Moderate) (n=66) and MRC 5 (Severe) dyspnoeic (n=60) groups. The patients were randomly assigned to an eight week programme of either exercise plus education (Exercise group) or education (Control group). Education and exercise programmes for the moderately dyspnoeic patients were carried out in a hospital outpatient setting. Severely dyspnoeic patients were all treated at home. Those in the Exercise group received an individualized training programme. There was a significant improvement in shuttle walking distance in the moderate dyspnoeic group, who received exercise training; baseline (mean+/-SEM) 191+/-22 m, post-rehabilitation 279+/-22 m (p<0.001). There was no improvement in exercise performance in the severely dyspnoeic patients receiving exercise. Neither group of control patients improved. Health status, assessed by the Total Chronic Respiratory Disease Questionnaire score, increased in the moderately dyspnoeic patients receiving exercise from 80+/-18 to 95+/-17 (p<0.0001) after rehabilitation. Much smaller changes were seen in the other three groups. Improvement in exercise performance and health status in patients with chronic obstructive pulmonary disease after an exercise programme depends on the initial degree of dyspnoea.

Using nasal intermittent positive pressure ventilation on a general respiratory ward

OBJECTIVES

To assess the use of nasal intermittent positive pressure ventilation (NIPPV) in treating acute-on-chronic respiratory failure in a general medical ward.

DESIGN

Retrospective analysis of clinical outcome.

SETTING

A general medical ward of a tertiary respiratory medicine referral centre.

SUBJECTS

Altogether 75 patients admitted with acute exacerbations of chronic respiratory failure and treated NIPPV.

MAIN OUTCOME MEASURES

Blood gas tensions determined at admission to hospital and during NIPPV, tolerance of NIPPV and mortality.

RESULTS

During treatment with NIPPV, the mean (SD) PaO2 increased rapidly by 2.31 (3.58) kPa (p < 0.0001), while the mean PaCO2 fell by 1.07 (1.74) kPa (p < 0.0001) and the mean pH increased by 0.03 (0.07) (p = 0.001). Altogether 57 (76%) of patients tolerated NIPPV, and (9.3%) died in hospital. Improvement in PaO2 was more noticeable in patients with chronic obstructive pulmonary disease (+3.13 (3.49) kPa, p < 0.0001) than in those with restrictive chest wall disease (+1.20 (3.07) kPa, p = 0.25) or obstructive sleep apnoea (+0.18 (3.64), p = 0.88). The reduction in PaCO2 was similar in all three groups.

CONCLUSIONS

In routine treatment of unselected patients with acute-on-chronic respiratory failure who are being cared for on a general ward, NIPPV rapidly improves hypoxaemia and hypercapnia, is well tolerated and is associated with low mortality.

Effect of exacerbation on quality of life in patients with chronic obstructive pulmonary disease

Exacerbations occur commonly in patients with moderate or severe chronic obstructive pulmonary disease (COPD) but factors affecting their severity and frequency or effects on quality of life are unknown. We measured daily peak expiratory flow rate (PEFR) and daily respiratory symptoms for 1 yr in 70 COPD patients (52 male, 18 female, mean age [+/- SD] 67.5 +/- 8.3 yr, FEV1 1.06 +/- 0.45 L, FVC 2.48 +/- 0.82 L, FEV1/FVC 44 +/- 15%, FEV1 reversibility 6.7 +/- 9.1%, PaO2 8.8 +/- 1.1 kPa). Quality of life was measured by the St. George's Respiratory Questionnaire (SGRQ). Exacerbations (E) were assessed at acute visit (reported exacerbation) or from diary card data each month (unreported exacerbation). In 61 (87%) patients there were 190 exacerbations (median 3; range, 1 to 8) of which 93 (51%) were reported. There were no differences in major symptoms (increase in dyspnea, sputum volume, or purulence) or physiological parameters between reported and unreported exacerbations. At exacerbation, median peak flow fell by an average of 6.6 L/min (p = 0.0003). Using the median number of exacerbations as the cutoff point, patients were classified as infrequent exacerbators (E = 0 to 2) or frequent exacerbators (E = 3 to 8). The SGRQ Total and component scores were significantly worse in the group that had frequent exacerbations: SGRQ Total score (mean difference = 14.8, p < 0.001), Symptoms (23.1, p < 0.001), Activities (12.2, p = 0.003), Impacts (13.9, p = 0.002). However there was no difference between frequent and infrequent exacerbators in the fall in peak flow at exacerbation. Factors predictive of frequent exacerbations were daily cough (p = 0.018), daily wheeze (p = 0.011), and daily cough and sputum (p = 0.009) and frequent exacerbations in the previous year (p = 0.001). These findings suggest that patient quality of life is related to COPD exacerbation frequency.

Upper airways sarcoidosis presenting as obstructive sleep apnoea

Sarcoidosis may present in a number of different ways, affecting many organ systems. The case history is presented of a 32 year old woman who presented with symptoms of severe obstructive sleep apnoea (OSA) due to infiltration of the upper airway by sarcoidosis. To our knowledge this presentation of sarcoidosis has not previously been described.

Nasal ventilation in pregnancy: treatment of nocturnal hypoventilation in a patient with kyphoscoliosis

The management of a young woman with congenital kyphoscoliosis, who developed symptomatic nocturnal hypoventilation during the third trimester of pregnancy, is described. Nasal intermittent positive pressure ventilation (NIPPV) was safely and effectively used to correct nocturnal hypoxaemia and hypercapnia from the 30th-36th week of gestation, when a healthy boy was delivered by Caesarean section. Following delivery, the mother no longer required NIPPV and returned to her prepregnancy level of activity.

Home assessment of activities of daily living in patients with severe chronic obstructive pulmonary disease on long-term oxygen therapy

In patients with severe chronic obstructive pulmonary disease (COPD) using long-term oxygen therapy (LTOT), few studies have investigated activities of daily living (ADL). We examined the relationships between ADL, quality of life, mood state and airways obstruction in patients using long-term oxygen therapy (LTOT) and in patients not requiring LTOT. We studied 23 patients (14 males, 9 females; median age 71, range 60-84 yrs) with COPD who received LTOT using oxygen concentrators (LTOT group). We also studied a control group of 19 patients (14 males, 5 females; median age 72, range 62-75 yrs) with COPD but without severe hypoxaemia (non-LTOT group). We found no significant difference between groups in health status using the St George's Respiratory Questionnaire (SGRQ). Median Nottingham Extended Activities of Daily Living (EADL) total scores were: LTOT group 10, non-LTOT 17; (p=0.01). Significant correlations (p<0.001) with Nottingham EADL score were found for Hospital Anxiety and Depression (HAD) score (rho=0.59), SGRQ Total score (rho=0.65) and percentage predicted forced expiratory volume in one second (FEV1) (rho=0.66). In conclusion, in patients with severe chronic obstructive pulmonary disease and broadly similar health status, those using long-term oxygen therapy were less independent in activities of daily living than those not requiring long-term oxygen therapy. Reduced independence in activities of daily living is, however, associated with the extent of airflow limitation, depression and poor health status, and does not, therefore, appear to be simply a result of restriction in movements imposed by the stationary device.

Does long-term oxygen therapy affect quality of life in patients with chronic obstructive pulmonary disease and severe hypoxaemia?

Long-term oxygen therapy (LTOT) improves survival in patients with hypoxaemic chronic obstructive pulmonary disease (COPD), but previous studies using general health measures have shown no effect on quality of life (QoL). In this study, the effect of LTOT on QoL was assessed using a disease-specific health measure, the St George's Respiratory Questionnaire (SGRQ). Twenty three hypoxaemic COPD patients (15 females and 8 males) were studied before and after starting LTOT: median age 71 (range 47-82) yrs, mean (SD) forced expiratory volume in one second (FEV1) 0.75 (0.22) L, arterial oxygen tension (Pa,O2) 6.95 (0.75) kPa, arterial carbon dioxide tension (Pa,CO2) 6.52 (1.21) kPa. A control group comprised 18 COPD patients (6 females and 12 males) with less severe hypoxaemia: median age 72 (range 58-85) yrs, FEV1 0.94 (0.33) L, Pa,O2 8.17 (0.94) kPa, Pa,CO2 6.02 (0.75) kPa. QoL was measured at baseline, 2 weeks, 3 and 6 months. The LTOT group had higher SGRQ total scores than controls (p<0.05) at all visits, implying lower QoL. Repeated measures analysis of variance showed no effect of LTOT on QoL over 6 months (F=0.43, p=0.79). In this study we detected no change in quality of life using a disease-specific health measure in patients with severe chronic obstructive pulmonary disease using an oxygen concentrator to provide long-term oxygen therapy.

Comparison of the efficacy of a demand oxygen delivery system with continuous low flow oxygen in subjects with stable COPD and severe oxygen desaturation on walking

BACKGROUND

Provision of ambulatory oxygen using an intermittent pulsed flow regulated by a demand oxygen delivery system (DODS) greatly increases the limited supply time of standard 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 random order to compare the efficacy of a demand 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.

Chronic noninvasive ventilation in obstructive airways disease

Early experience with noninvasive ventilation in patients with chronic obstructive pulmonary disease was largely unsuccessful, with no benefit over long-term oxygen therapy. Nasal positive pressure ventilation, however, produces improvements in arterial blood gases, nocturnal-hypoventilation, and quality of life. Experience with nasal ventilation in other obstructive airways diseases, such as bronchiectasis and cystic fibrosis, is limited and less favorable.

Ambulatory oxygen in chronic obstructive pulmonary disease

Ambulatory oxygen therapy in patients with COPD and exercise hypoxaemia may improve exercise capacity and breathlessness. The improvement in exercise tolerance is related to the degree of exercise hypoxaemia. As effects from ambulatory oxygen therapy are prone to placebo effects, careful patient selection is required, with formal assessment. For effective ambulatory oxygen delivery, oxygen should be provided either by small liquid oxygen tanks or by small lightweight cylinders and conserving devices. Studies are required to evaluate the longer term effects of ambulatory oxygen on daily life.

Comparison of characteristics of patients and treatment outcome for pulmonary non-tuberculous mycobacterial infection and pulmonary tuberculosis

BACKGROUND

Patients with non-tuberculous mycobacteria are usually started on conventional antituberculous triple therapy once acid fast bacilli are detected, before the exact type of mycobacteria has been identified. The ability to identify the characteristics of patients with tuberculous and non-tuberculous mycobacteria may be helpful in identifying before treatment those patients more likely to have non-tuberculous infection.

METHODS

A retrospective study was conducted of all patients in one unit in whom non-tuberculous mycobacteria were identified in sputum or bronchoalveolar washings in the period 1987-93. The pattern of drug resistance was determined from laboratory records, and all case notes and chest radiographs were reviewed to identify the underlying disease and treatment outcome. All cases were compared with a matched control group of patients with culture positive Mycobacterium tuberculosis diagnosed during the same period.

RESULTS

In the period studied there were 70 non-tuberculous and 221 tuberculous isolates. The non-tuberculous bacteria were typed as follows: M xenopi 23 (33%), M kansasii 19 (27%), M fortuitum 14 (20%), others 14 (20%). Of those with non-tuberculous mycobacteria, 83% were white subjects compared with 47% for tuberculosis. Patients with non-tuberculous mycobacteria were older than those with tuberculosis. Pre-existing lung disease or AIDS was present in 81% of patients with non-tuberculous mycobacteria and in 17% of patients with tuberculosis. Sensitivity to rifampicin and ethambutol was seen in 95% of M xenopi and 96% of M kansasii isolates. Relapse occurred in 60% of cases infected with M xenopi, 20% infected with M kansasii, and in 7% of cases with tuberculosis.

CONCLUSIONS

In the population studied non-tuberculous mycobacteria occurred most frequently in elderly white subjects with pre-existing lung disease. If mycobacteria are detected in this group, consideration should be given to the possibility of non-tuberculous infection before embarking on treatment. A combination containing rifampicin and ethambutol is effective. The relapse rate for infection with M xenopi is high and prospective studies of the effect of the above combination of antituberculosis drugs are needed.

Nasal positive pressure ventilation in COPD

Long-term oxygen therapy improves survival in patients with chronic obstructive pulmonary disease (COPD), though the addition of assisted ventilation may control the nocturnal hypoventilation and correct blood gases. Although early experiences with ventilation in COPD was disappointing, the introduction of nasal positive pressure ventilation has been shown to improve blood gases, sleep quality and quality of life. The improvement in blood gases was related to the reduction of overnight Pa,CO2 with ventilation. Compliance with nasal ventilation was increased, compared to that with earlier modes of ventilation. Nasal ventilation is beneficial in carefully selected patients with hypercapnic COPD.

Quality of life in patients with chronic obstructive pulmonary disease and severe hypoxaemia

BACKGROUND

Patients with severe chronic obstructive pulmonary disease (COPD) have impairment in most areas of quality of life, but a relationship between impairment of the partial pressure of oxygen in arterial blood (PaO2) and quality of life has not been established. Previous studies used general health measures such as the Sickness Impact Profile (SIP). In this study a disease-specific health measure, the St George's Respiratory Questionnaire (SGRQ), was used to examine the relationship.

METHODS

Forty one patients (20 men) of median age 71 years (range 47-85) with COPD were assessed. Forced expiratory volume in one second (FEV1), PaO2 and partial pressure of carbon dioxide in the arterial blood (PaCO2) were measured, and the patients completed the SGRQ, SIP, and the Hospital Anxiety and Depression Scale (HAD).

RESULTS

The mean (SD) values were: FEV1, 0.83 (0.29) litres; PaO2, 7.49 (1.03) kPa; PaCO2, 6.30 (1.05) kPa; SGRQ total score, 55.3 (18.2); SIP total score 15.4 (9.2); anxiety score, 5.7 (4.3); depression score, 5.3 (3.4). PaO2 was significantly correlated with the SGRQ total scores but not with the SIP total score. The SGRQ total score also correlated with anxiety and depression. Multivariate analysis showed that depression score and PaO2 were both significant covariates of the SGRQ total score.

CONCLUSIONS

These findings suggest that, in patients with severe COPD, quality of life is related to the severity of hypoxaemia, but this relationship is only detectable when using a disease-specific health measure.

Nasal pressure support ventilation plus oxygen compared with oxygen therapy alone in hypercapnic COPD

Non-invasive ventilation has been used in chronic respiratory failure due to chronic obstructive pulmonary disease (COPD), but the effect of the addition of nasal positive-pressure ventilation to long-term oxygen therapy (LTOT) has not been determined. We report a randomized crossover study of the effect of the combination of nasal pressure support ventilation (NPSV) and domiciliary LTOT as compared with LTOT alone in stable hypercapnic COPD. Fourteen patients were studied, with values (mean +/- SD) of Pao2 of 45.3 +/- 5.7 mm Hg, PaCO2 of 55.8 +/- 3.6 mm Hg, and FEV1 of 0.86 +/- 0.32 L. A 4 wk run-in period (on usual therapy) was followed by consecutive 3-mo periods of: (1) oxygen therapy alone, and (2) oxygen plus NPSV in randomized order. Assessments were made during run-in and at the end of each study period. There were significant improvements in daytime arterial PaO2 and PaCO2, total sleep time, sleep efficiency, and overnight PaCO2 following 3 mo of oxygen plus NPSV as compared with run-in and oxygen alone. Quality of life with oxygen plus NPSV was significantly better than with oxygen alone. The degree of improvement in daytime PaCO2 was correlated with the improvement in mean overnight PaCO2. Nasal positive-pressure ventilation may be a useful addition to LTOT in stable hypercapnic COPD.

Respiratory depression following morphine and morphine-6-glucuronide in normal subjects

1. Morphine 6-glucuronide (M6G) is a metabolite of morphine with analgesic activity. A double-blind, randomised comparison of the effects of morphine and M6G on respiratory function was carried out in 10 normal subjects after i.v. morphine (10 mg 70 kg-1) or M6G (1, 3.3 and 5 mg 70 kg-1). Analgesic potency was also assessed using an ischaemic pain test and other toxic effects were monitored. 2. Following morphine there was a significant increase in arterial PCO2, as measured by blood gases 45 min post dose (0.54 +/- 0.24 (s.d.) kPa, P < 0.001), and in transcutaneous PCO2 from 15 min post dose until the end of the study period (4 h), whereas blood gas and transcutaneous PCO2 were unchanged after M6G at 1.0, 3.3 and 5.0 mg 70 kg-1. This increased PCO2 following morphine was associated with an increase in expired CO2 concentration (FECO2) (0.20 +/- 0.14% expired air at 15 min post dose, P = 0.002), compared with small but significant reductions in FECO2 following morphine 6-glucuronide (-0.15 +/- 0.17% at 1 mg 70 kg-1 P = 0.030, -0.14 +/- 0.15% at 3.3 mg 70 kg-1 P = 0.017, -0.18 +/- 0.11% at 5 mg 70 kg-1 P = 0.024). Maximum transcutaneous PCO2 was significantly increased after morphine (0.63 +/- 0.28 kPa P = 0.009), but was not changed after M6G at 1 mg (0.10 +/- 0.34 kPa P = 0.11) 3.3 mg (0.06 +/- 0.37 kPa P = 0.34) or 5 mg (0.26 +/- 0.07 kPa P = 0.10).(ABSTRACT TRUNCATED AT 250 WORDS)

Ambulatory oxygen therapy in stable kyphoscoliosis

Patients with chronic obstructive pulmonary disease (COPD) may benefit from ambulatory oxygen; however, the effect of exercise on arterial oxygen saturation (Sa,O2) in patients with kyphoscoliosis and of correction with ambulatory oxygen have not been previously reported. Twelve patients with stable kyphoscoliosis (mean (SD) Cobb angle 79 (26) degrees) were studied, with mean (SD) arterial oxygen tension (Pa,O2) 8.96 (0.93) kPa, arterial carbon dioxide tension (Pa,CO2) 6.52 (0.66), forced expiratory volume in one second (FEV1) 0.90 (0.15) L, forced vital capacity (FVC) 1.34 (0.46) L. Six-minute walking tests with oximetry and visual analogue scores (VAS) for breathlessness were performed on air (baseline), and with cylinders containing air and oxygen at 2 L-min-1. Cylinder walks were in random order, with patients blinded to cylinder content. Patients showed oxygen desaturation at each stage of the study. At baseline, oxygen desaturation during exercise was correlated with deterioration in VAS breathlessness scores. Ambulatory oxygen produced significant improvements in desaturation, breathlessness scores and recovery time compared to baseline and air cylinder walks. There was no relationship between baseline desaturation and changes in walking distance. Although exercise desaturation, breathlessness and recovery times were significantly improved with ambulatory oxygen at 2 L.min-1, walking distance was unaffected. We conclude that patients with moderate to severe kyphoscoliosis have significant oxygen desaturation on exercise and should thus routinely receive oximetry on exercise and assessment for ambulatory oxygen therapy.

Ambulatory oxygen therapy in stable kyphoscoliosis

Patients with chronic obstructive pulmonary disease (COPD) may benefit from ambulatory oxygen; however, the effect of exercise on arterial oxygen saturation (Sa,O2) in patients with kyphoscoliosis and of correction with ambulatory oxygen have not been previously reported. Twelve patients with stable kyphoscoliosis (mean (SD) Cobb angle 79 (26) degrees) were studied, with mean (SD) arterial oxygen tension (Pa,O2) 8.96 (0.93) kPa, arterial carbon dioxide tension (Pa,CO2) 6.52 (0.66), forced expiratory volume in one second (FEV1) 0.90 (0.15) L, forced vital capacity (FVC) 1.34 (0.46) L. Six-minute walking tests with oximetry and visual analogue scores (VAS) for breathlessness were performed on air (baseline), and with cylinders containing air and oxygen at 2 L-min-1. Cylinder walks were in random order, with patients blinded to cylinder content. Patients showed oxygen desaturation at each stage of the study. At baseline, oxygen desaturation during exercise was correlated with deterioration in VAS breathlessness scores. Ambulatory oxygen produced significant improvements in desaturation, breathlessness scores and recovery time compared to baseline and air cylinder walks. There was no relationship between baseline desaturation and changes in walking distance. Although exercise desaturation, breathlessness and recovery times were significantly improved with ambulatory oxygen at 2 L.min-1, walking distance was unaffected. We conclude that patients with moderate to severe kyphoscoliosis have significant oxygen desaturation on exercise and should thus routinely receive oximetry on exercise and assessment for ambulatory oxygen therapy.

Nasal ventilation in acute exacerbations of chronic obstructive pulmonary disease: effect of ventilator mode on arterial blood gas tensions

BACKGROUND

There are no controlled trials of the use of different modes of nasal intermittent positive pressure ventilation (NIPPV) in patients with exacerbations of chronic obstructive pulmonary disease (COPD). This study describes the effect on blood gas tensions of four different modes of nasal ventilation.

METHODS

Twelve patients with acute exacerbations of COPD were studied (mean (SD) FEV1 0.59 (0.13) l, PaO2 (air) 5.10 (1.12) kPa, PaCO2 9.28 (1.97) kPa, pH 7.32 (0.03)). Each patient underwent four one-hour periods of nasal ventilation in randomised order: (a) inspiratory pressure support 18 cm H2O; (b) pressure support 18 cm H2O+positive end expiratory pressure (PEEP) 6 cm H2O (IPAP+EPAP); (c) continuous positive airway pressure (CPAP) 8 cm H2O; and (d) volume cycled NIPPV. Arterial blood samples were obtained before each period of ventilation and at one hour.

RESULTS

Pressure support, CPAP, and volume cycled NIPPV all produced significant improvements in PaO2; there was no difference between these three modes. The change in PaO2 with IPAP+EPAP did not reach statistical significance. None of the modes produced significant changes in mean PaCO2; patients with higher baseline levels tended to show a rise in PaCO2 whereas those with lower baseline levels tended to show a fall.

CONCLUSIONS

Although PaO2 improved in all patients there are differences in efficacy between the modes, while the changes in PaCO2 were variable. The addition of EPAP conferred no advantage in terms of blood gas tensions.

Domiciliary oxygen cylinders: indications, prescription and usage

Oxygen therapy for use in the home can be prescribed in two forms: oxygen concentrators are used to provide long term domiciliary oxygen therapy (LTOT), and oxygen cylinders are used to provide oxygen intermittently for relief of symptoms. In this study prescription and usage of oxygen cylinders in the home were assessed. All patients using oxygen cylinders at home in the London Borough of Tower Hamlets in October 1992 were studied. A questionnaire was sent to each patient; further information was obtained from a questionnaire to the general practitioner and from hospital notes where available. Patients with a diagnosis of chronic obstructive pulmonary disease (COPD) were visited at home to measure oxygen saturation levels (SaO2). The main outcome measures were the proportion of oxygen cylinder users who had undergone a full respiratory assessment and the number who might benefit from LTOT. There were 56 patients using oxygen intermittently, 77% with COPD of which 28% had an SaO2 < or = 92%. In these 56 patients 27% had not been assessed by a hospital physician for their chest disease, 58% used their oxygen at least once a day and on average these patients used three cylinders each per month. Most patients using oxygen cylinders at home have a diagnosis of COPD and use oxygen regularly for short term relief of breathlessness; many have not been assessed by a respiratory physician. Measurement of SaO2 suggested that a significant minority might benefit from LTOT and would certainly warrant further evaluation.

Nasal masks for domiciliary positive pressure ventilation: patient usage and complications

BACKGROUND

Nasal mask discomfort is a major factor in compliance with treatment by nasal intermittent positive pressure ventilation (NIPPV) and nasal continuous positive airway pressure (CPAP).

METHODS

A study of skin complications resulting from mask usage, with particular reference to predisposing factors, was carried out in 66 patients by means of a postal questionnaire. An effective means of managing ulceration at the nasal bridge while continuing therapy is described.

RESULTS

Some disruption of treatment due solely to mask discomfort was experienced by 35 patients (53%), consisting of broken skin or open sores in 11 cases (17%). CONCLUSIONS-Although complications resulting from nasal mask usage are common, early identification of patients at risk of developing such complications and appropriate intervention will result in improved patient compliance.

Arterialised earlobe blood gas analysis: an underused technique

BACKGROUND

Techniques for sampling arterialised capillary blood from the finger pulp and the earlobe were first described over two decades ago but, although close agreement between arterial values and earlobe samples has been demonstrated in normal subjects, this technique is not in common usage.

METHODS

Forty patients with chronic lung disease and a wide range of arterial blood gas values were studied. Simultaneous earlobe and arterial samples were drawn with the patient at rest and analysed in the same blood gas analyser. The respiratory function laboratory staff in 50 UK hospitals with a respiratory department were telephoned and asked whether the technique was used in their hospital and the reasons, if known, for not adopting it.

RESULTS

Earlobe and arterial blood gas tensions agreed closely over a wide range of values of arterial pH, PCO2 (mean difference 0.21, 95% confidence intervals -0.24 to +0.67 kPa) and PO2 (mean difference -0.17, 95% confidence intervals -1.09 to +0.75 kPa), especially at arterial PO2 values lower than 8 kPa. Of 50 UK centres surveyed 18% used the arterialised earlobe technique and 4% had plans to introduce it. Reasons for not using it were lack of knowledge in 64%, no blood gas analyser in 6%, the technique was considered inaccurate in 4%, and insufficient staff in 4%.

CONCLUSIONS

Although earlobe blood gas analysis is sufficiently accurate to be reliably substituted for arterial sampling in routine clinical practice, most centres in the UK do not use the technique. The main reasons for this appear to be lack of knowledge of its existence and uncertainty over its accuracy.

Assessment and follow up of patients prescribed long term oxygen treatment

BACKGROUND

Prescription and use of long term oxygen treatment were audited in a large group of patients after more than five years of use of the guidelines for its prescription.

METHODS

Patients with a concentrator were interviewed at home with a structured questionnaire in three family health service authorities in East London. Stable oxygen saturation (SaO2) breathing air and oxygen, forced expiratory volume in one second (FEV1) and current and previous dated concentrator meter readings were recorded. A further questionnaire was sent to each patient's general practitioner. Hospital case notes of patients who did not meet the criteria for long term oxygen treatment at reassessment were reviewed.

RESULTS

A total of 176 patients were studied; 84% had chronic obstructive lung disease and 19% admitted to continued smoking; 140 patients had seen a respiratory physician but results of respiratory assessment were available to their general practitioner in fewer than 54 cases. FEV1 was < 1.5 1 in 158 patients but in 67 SaO2 was less than 91% breathing air, mainly in patients with chronic obstructive lung disease who had been inadequately assessed. Daily oxygen was prescribed for a median of 15 (range 4-24) hours and measured daily use was 15 (0-24) hours; 74% of patients used more than 12 hours. Only 35 patients had problems with oxygen treatment, but 29 had an undercorrected SaO2 of less than 92% when using their concentrator.

CONCLUSIONS

Guidelines for prescription of long term oxygen treatment are largely followed and most patients complied with treatment. Increased communication about respiratory state is required between hospital doctors and general practitioners. Patients need regular reassessments to ensure that hypoxaemia is corrected and that oxygen is appropriately prescribed.

Comparison of pressure and volume preset nasal ventilator systems in stable chronic respiratory failure

Nasal intermittent positive pressure ventilation (NIPPV) has been widely used in the treatment of chronic respiratory disease. Ventilators may be volume or pressure preset; each type has theoretical advantages, but to date there has been no formal comparison. We wanted to assess the efficacy on blood gas changes that may be achieved and overall acceptability of four nasal ventilators (two pressure preset: Respironics bilevel positive airway pressure (BiPAP) and the Thomas NIPPY; and two volume preset: BromptonPac and Monnal-D) in patients with stable chronic respiratory failure. Median age was 59 yrs (range 48-71 yrs), mean (SD) arterial oxygen tension (PaO2) 7.16 (0.21) kPa, arterial carbon dioxide tension (PaCO2) 7.02 (0.35) kPa, forced expiratory volume in one second (FEV1) 0.76 (0.24) l, and forced vital capacity (FVC) 1.58 (0.49) l. All had previously used NIPPV. There were significant changes in blood gases at 2 h with each ventilator: mean change (95% confidence interval); BiPAP PaO2 +1.52 (0.95-2.09) kPa, PaCO2-1.04 (1.55-0.54) kPa; NIPPY PaO2 +1.63 (0.85-2.41) kPa, PaCO2, -1.1 (1.86-0.34) kPa; BromptonPac PaO2 +1.22 (0.75-1.67) kPa, PaCO2 -1.14 (1.52-0.76) kPa; Monnal-D PaO2 +1.14 (0.42-1.84) kPa, PaCO2 -1.19 (2.14-0.23) kPa. Analysis of variance showed no significant differences in the efficacy of volume or pressure preset equipment, and all ventilators proved equally acceptable to the patients studied. We conclude that all four of the volume or pressure preset ventilators examined are suitable for the delivery of nasal intermittent positive pressure ventilation in patients with stable chronic respiratory failure.

Comparison of pressure and volume preset nasal ventilator systems in stable chronic respiratory failure

Nasal intermittent positive pressure ventilation (NIPPV) has been widely used in the treatment of chronic respiratory disease. Ventilators may be volume or pressure preset; each type has theoretical advantages, but to date there has been no formal comparison. We wanted to assess the efficacy on blood gas changes that may be achieved and overall acceptability of four nasal ventilators (two pressure preset: Respironics bilevel positive airway pressure (BiPAP) and the Thomas NIPPY; and two volume preset: BromptonPac and Monnal-D) in patients with stable chronic respiratory failure. Median age was 59 yrs (range 48-71 yrs), mean (SD) arterial oxygen tension (PaO2) 7.16 (0.21) kPa, arterial carbon dioxide tension (PaCO2) 7.02 (0.35) kPa, forced expiratory volume in one second (FEV1) 0.76 (0.24) l, and forced vital capacity (FVC) 1.58 (0.49) l. All had previously used NIPPV. There were significant changes in blood gases at 2 h with each ventilator: mean change (95% confidence interval); BiPAP PaO2 +1.52 (0.95-2.09) kPa, PaCO2-1.04 (1.55-0.54) kPa; NIPPY PaO2 +1.63 (0.85-2.41) kPa, PaCO2, -1.1 (1.86-0.34) kPa; BromptonPac PaO2 +1.22 (0.75-1.67) kPa, PaCO2 -1.14 (1.52-0.76) kPa; Monnal-D PaO2 +1.14 (0.42-1.84) kPa, PaCO2 -1.19 (2.14-0.23) kPa. Analysis of variance showed no significant differences in the efficacy of volume or pressure preset equipment, and all ventilators proved equally acceptable to the patients studied. We conclude that all four of the volume or pressure preset ventilators examined are suitable for the delivery of nasal intermittent positive pressure ventilation in patients with stable chronic respiratory failure.

Randomised controlled trial of nasal ventilation in acute ventilatory failure due to chronic obstructive airways disease

Acute exacerbations of chronic obstructive airways disease (COAD) are a common cause of admission to hospital, and have a high mortality. Nasal intermittent positive pressure ventilation (NIPPV) has been used successfully in patients with respiratory failure due to neuromuscular and skeletal disorders, but the outcome of treatment in patients with COAD is less well known. We carried out a prospective randomised controlled trial of conventional treatment versus conventional treatment plus NIPPV, in 60 patients with acute ventilatory failure due to exacerbations of COAD. For the NIPPV group there was a rise in pH, compared with a fall in the controls (mean difference of change between the groups 0.046 [95% CI 0.06-0.02, p < 0.001]), and a larger fall in PaCO2 (mean difference in change between the groups 1.2 kPa [95% CI 0.45 to 2.03, p < 0.01]). Median visual analogue scores over the first 3 days of admission showed less breathlessness in the NIPPV group (2.3 cm [range 0.1-5.5]) than in the control group (4.5 cm [range 0.9-8.8]) (p < 0.025). Survival rates at 30 days were compared for intention-to-treat and efficacy populations. In the efficacy mortality comparison, mortality in the NIPPV group was reduced: 1/26 vs 9/30 (relative risk = 0.13, CI = 0.02-0.95, p = 0.014). This effect was less in the intention-to-treat analysis: 3/30 vs 9/30 (relative risk = 0.33, CI = 0.10-1.11, p = 0.106). In patients with acute ventilatory failure due to COAD who received NIPPV there was a significant rise in pH, a reduction in PaCO2 and breathlessness, and reduced mortality.

Nasal intermittent positive-pressure ventilation in weaning intubated patients with chronic respiratory disease from assisted intermittent, positive-pressure ventilation

Nasal intermittent positive-pressure ventilation (NIPPV) has been used for domiciliary ventilatory support, and to avoid intubation for acute respiratory failure in patients with chronic airflow limitation (CAL). Its role in weaning patients from assisted ventilation in intensive care has not been defined. We have used NIPPV to wean 14 patients with respiratory disease who were referred either because of predicted difficulty in weaning or failure to wean using standard techniques. Twelve patients were ventilated for acute respiratory failure; eight patients had CAL and four had chest wall or neuromuscular disease. Two further patients with chest disease were difficult to wean following surgery. Weaning was successful in 13 patients. NIPPV corrected hypoxia, reduced hypercapnia and was well tolerated. Weaning from NIPPV was achieved in all patients with CAL, although three patients with chest wall disease later required domiciliary ventilatory support. All but one of the patients survived to leave hospital. NIPPV may have an important role in weaning from assisted ventilation, particularly in patients with underlying chronic respiratory disease. This preliminary report needs to be followed by a controlled study comparing NIPPV with established weaning methods.

Comparison of nasal pressure support ventilation with nasal intermittent positive pressure ventilation in patients with nocturnal hypoventilation

Nasal intermittent positive pressure ventilation (NIPPV) provides effective ventilatory support in patients with nocturnal hypoventilation. Nasal pressure support ventilation (NPSV), which only provides ventilation in response to patient triggering, may also be effective, simpler, and cheaper, but has not been evaluated. NIPPV and NPSV were compared in 12 patients with nocturnal hypoventilation, requiring domiciliary ventilatory support. The patients were studied on three consecutive nights, in random order: a control night without ventilation and a night on each mode of ventilatory support using the bilevel positive airway pressure (BiPAP) ventilator. Both NIPPV and NPSV significantly increased mean arterial oxygen saturation (SaO2) compared to the control night (NIPPV mean increase 4.1%; 95% confidence interval (CI) 2.2 to 6.1, NPSV 4.4%; CI 2.1 to 6.6) with no significant difference between the two modes. The percentage of the study night spent below 90% SaO2 was significantly reduced by both ventilator modes compared to the control night (median reduction on NIPPV 37%; CI -54 to -10, reduction on NPSV 31%; CI -53 to -9, with no significant difference between NPSV and NIPPV. NPSV was as effective as NIPPV in patients with nocturnal hypoventilation, which suggests that these patients are able to trigger the ventilator adequately. The lower cost of NPSV will make it accessible to more patients with chronic lung disease.

Comparison of nasal pressure support ventilation with nasal intermittent positive pressure ventilation in patients with nocturnal hypoventilation

Nasal intermittent positive pressure ventilation (NIPPV) provides effective ventilatory support in patients with nocturnal hypoventilation. Nasal pressure support ventilation (NPSV), which only provides ventilation in response to patient triggering, may also be effective, simpler, and cheaper, but has not been evaluated. NIPPV and NPSV were compared in 12 patients with nocturnal hypoventilation, requiring domiciliary ventilatory support. The patients were studied on three consecutive nights, in random order: a control night without ventilation and a night on each mode of ventilatory support using the bilevel positive airway pressure (BiPAP) ventilator. Both NIPPV and NPSV significantly increased mean arterial oxygen saturation (SaO2) compared to the control night (NIPPV mean increase 4.1%; 95% confidence interval (CI) 2.2 to 6.1, NPSV 4.4%; CI 2.1 to 6.6) with no significant difference between the two modes. The percentage of the study night spent below 90% SaO2 was significantly reduced by both ventilator modes compared to the control night (median reduction on NIPPV 37%; CI -54 to -10, reduction on NPSV 31%; CI -53 to -9, with no significant difference between NPSV and NIPPV. NPSV was as effective as NIPPV in patients with nocturnal hypoventilation, which suggests that these patients are able to trigger the ventilator adequately. The lower cost of NPSV will make it accessible to more patients with chronic lung disease.

Ambulatory oxygen in chronic heart failure

Ambulatory oxygen therapy may be of benefit in bicycle exercise tests. We have assessed the effects of ambulatory oxygen during walk tests in 12 patients with chronic heart failure. In 6 min walks with the patient breathing air, mean (SD) arterial oxygen saturation (SaO2) fell from 94.4 (3.7)% at rest to 90.1 (6.1)% (p = 0.014) on exercise. 21/min oxygen increased resting SaO2 from 93.7 (4.0)% (air cylinder) to 96.5 (3.0)% (p < 0.001) with no effect on minimum SaO2, distance, or breathlessness. During endurance walks, 4 l/min oxygen increased minimum SaO2 from 90.4 (5.6)% to 93.5 (4.7)% (p = 0.011) but also had no effect on breathlessness or distance. Ambulatory oxygen in currently available cylinders cannot be recommended for patients with chronic heart failure.

Short-term use of fluoxetine in asymptomatic obese subjects with sleep-related hypoventilation

Disordered nocturnal breathing with significant arterial oxygen desaturation and sleep apnoea is a feature of extreme obesity which is often difficult to manage in the short term. We have evaluated the effect of fluoxetine, a centrally acting 5-HT re-uptake inhibitor, on sleep-breathing patterns in asymptomatic extremely obese subjects. A double-blind cross-over study was used to compare fluoxetine (60 mg for three days) to placebo. Eleven obese subjects (ten males, one female, mean weight +/- s.d. 131 +/- 2 kg) slept overnight in a sleep laboratory with the polysomnographic study recorded after an initial acclimatization night. The obese subjects had normal respiratory function and normal fully awake arterial oxygen saturation (%SaO2 97 +/- 1). Marked O2 desaturation was seen in all the subjects during sleep but the average asleep %SaO2 did not differ between the two treatment phases (placebo 90 +/- 5; fluoxetine 92 + 2%). However, fluoxetine significantly increased the minimum %SaO2 recorded during the study night either by abolishing or reducing REM sleep (placebo 73 +/- 2%; fluoxetine 81 +/- 8%; P < 0.05, 95% CI -12.3 to -2.03). Frequent hypopnoea was observed in all subjects in both REM and non-REM sleep whereas apnoea was uncommon. The total apnoea/hypopnoea index fell in six subjects during the fluoxetine night, the largest reduction being seen in the most severely affected. In five of the six the improvement was associated with the abolition of REM sleep. Total sleep time did not differ between the placebo and fluoxetine nights nor did a qualitative assessment of sleep using a visual analogue score.(ABSTRACT TRUNCATED AT 250 WORDS)

Domiciliary nocturnal nasal intermittent positive pressure ventilation in hypercapnic respiratory failure due to chronic obstructive lung disease: effects on sleep and quality of life

BACKGROUND

Domiciliary assisted ventilation, using negative or positive pressure devices, is an effective treatment for respiratory failure due to chest wall deformity and neuromuscular disease. Negative pressure ventilators have been used with some success in patients with chronic obstructive lung disease in hospital, but attempts to continue treatment at home have been disappointing. This study evaluates the practicalities of nasal intermittent positive pressure ventilation at home in patients with chronic obstructive lung disease and the effect on sleep and quality of life.

METHODS AND RESULTS

Twelve patients with chronic obstructive lung disease and hypercapnic respiratory failure received nasal intermittent positive pressure ventilation at home during sleep. At six months eight were continuing with the ventilation. One patient had died and three had withdrawn because they were unable to sleep with the equipment. Full polysomnography performed during ventilation in patients continuing treatment at six months showed an increase in mean PaO2 of 11% (+2% to +23%) and lower mean transcutaneous carbon dioxide tensions (by -2.7 (-1.3 to -5.1) kPa) overnight compared with spontaneous breathing before the start of nasal intermittent positive pressure ventilation. Total sleep time and sleep efficiency changed during ventilation by +72.5 (+21 to +204) minutes and +5% (-3% to +30%) respectively; sleep architecture and the number of arousals were unchanged. Quality of life did not change but was no worse during ventilation. At one year seven patients were still using the ventilator and PaCO2 and bicarbonate ion concentration during the day had improved further by comparison with the values at six months (change from baseline -1.7 (-2.1 to -0.6) kPa, p less than 0.05, and -6.3 (-11.9 to -4) mmol/l, p less than 0.05).

CONCLUSIONS

Nasal intermittent positive pressure ventilation can be used effectively at home during sleep in selected patients with chronic obstructive lung disease. Its future place in management can be established only by formal comparison with long term oxygen therapy.

Comparison of liquid and gaseous oxygen for domiciliary portable use

BACKGROUND

Liquid oxygen is available for portable use and may have advantages over gas cylinders.

METHODS

The use and acceptability of liquid and gaseous oxygen was compared in 15 patients with chronic lung disease who had shown an improvement of at least 10% in assessments of exercise tolerance and breathlessness with standard portable oxygen. Gaseous and liquid portable oxygen were provided in random order for two eight week periods, and assessments consisted of six minute walking tests, lung function tests, chronic respiratory disease index questionnaires, and diary cards.

RESULTS

The walking distance was not significantly affected by the weight of the equipment with either system. Patients used the liquid oxygen for significantly longer (23.5 hours a week) than the gas cylinder (10 hours a week). When using liquid oxygen patients went out of the house on average for 19.5 hours a week, compared with 15.5 hours a week with gaseous oxygen. The liquid oxygen system was preferred because the oxygen lasted longer, filling was easier, and the canister was easier to carry.

CONCLUSIONS

Liquid oxygen for portable treatment may be of benefit in selected patients with chronic lung disease.