Home Overnight Pulse Oximetry in Patients With COPD: More Than One Recording May Be Needed

doi:10.1378/chest.123.4.1127

Chest

Volume 123, Issue 4, April 2003, Pages 1127-1133

https://doi.org/10.1378/chest.123.4.1127 Get rights and content

Study objectives:

Home overnight pulse oximetry (OPO) is used to assess nocturnal desaturation in patients with COPD, but the current practice of relying on one recording has not been studied. We assessed the variability of nocturnal desaturation in patients with COPD between nights, as measured by home OPO.

Design:

Study subjects attended for clinical evaluation, spirometry, and arterial blood gas analysis. OPO was prospectively completed at home on 2 consecutive nights (study night 1 [N1] and study night 2 [N2]) and repeated at 3 weeks (study night 3 [N3]).

Setting:

Respiratory Services, Green Lane Hospital, Auckland, New Zealand.

Patients:

Twenty-six patients with clinically stable COPD (mean age, 69.3 years [SD, 6.9]; FEV₁, 28.6% predicted [SD, 10.6]; Po₂, 71.3 mm Hg [SD, 9.8]). Patients with asthma or clinical evidence of obstructive sleep apnea were excluded.

Measurements and results:

Mean nocturnal saturation (MNS) and time spent with saturation below 90% (TB90%) were calculated for N1, N2, and N3. Group mean recording length, MNS, and TB90% were similar for each night. Little variation in MNS was seen between nights (N1 and N2 mean difference, 1.31%; N2 and N3, 1.26%; N1 and N3, 1.25%). Larger variation was seen between nights for TB90% (N1 and N2 mean difference, 17.46%; N2 and N3, 9.95%; N1 and N3, 14.05%). No factors were identified that predicted increased variability of TB90%. Using the current definition of “significant nocturnal desaturation” (TB90% ≥ 30% of the night), 9 of 26 patients (34.6%) changed category between “desaturator” and “nondesaturator” from N1 to N2.

Conclusion:

Nocturnal desaturation in patients with COPD exhibits considerable night-to-night variability when measured by home OPO. A single home OPO recording may be insufficient for accurate assessment of nocturnal desaturation.

Section snippets

Subjects

Subjects were recruited from outpatient services at Green Lane Hospital, Auckland, New Zealand. Eligible patients had moderate-to-severe COPD defined clinically and physiologically according to British Thoracic Society criteria.¹³ Subjects had to be in clinically stable condition with no exacerbation for at least 4 weeks. Exacerbation was defined as per the Inhaled Steroids in Obstructive Lung Disease in Europe study,¹⁴ as a deterioration in respiratory symptoms that required treatment with

Baseline Characteristics

A total of 26 subjects participated in the study (29 subjects were approached, and 3 subjects declined to participate), of which 22 were male, 1 was a current smoker, and the other 25 were ex-smokers. Subjects had moderate-to-severe COPD with mean postbronchodilator FEV₁ of 28.6% predicted and mean reversibility of 153 mL, but relatively well preserved resting oxygenation (Table 1).

Most subjects were in stable states over the study period, and final group mean Po₂ and Pco₂ at 3 weeks were

Discussion

This study demonstrated considerable variability in nocturnal desaturation between nights in patients with moderate-to-severe COPD without daytime hypoxemia, when measured using home OPO. The variability was of a degree that would have influenced clinical decision making in over one third of patients. Direct assessment of nocturnal desaturation by OPO is needed in patients with COPD, because this study and previous research have shown that the degree of nocturnal desaturation such patients

Conclusion

We have demonstrated that patients with COPD and nocturnal desaturation display substantial variability in the extent of nocturnal desaturation when measured at home with a pulse oximeter. Similar variability occurs both on consecutive nights and over time, and variability is greatest when desaturation is expressed as the TB90%. Differences in sleep quality, disease severity, or the length of oximetry recording did not appear to explain the degree of variability seen in this study. Thus, the

ACKNOWLEDGMENT

The authors thank Pam Young, Senior Physiotherapist for her advice and help with patient recruitment, and Teena West, Biostatistician, for help with the statistical analyses and preparation of the illustrations.

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Exertional hypoxemia in stable COPD is common and predicted by circulating proadrenomedullin
2014, Chest
Citation Excerpt :
Accordingly, only 30% of the patients showed consistent reductions of Sao2 ≤ 88% in all three tests performed within 12 days. This phenomenon has been also described regarding nocturnal desaturation in COPD.51 Our study confirms the fact that exertional hypoxemia is found intermittently in patients with COPD.
The prevalence of exertional hypoxemia in unselected patients with COPD is unknown. Intermittent hypoxia leads to adrenomedullin (ADM) upregulation through the hypoxia-inducible factor-1 pathway. We aimed to assess the prevalence and the annual probability to develop exertional hypoxemia in stable COPD. We also hypothesized that increased ADM might be associated with exertional hypoxemia and envisioned that adding ADM to clinical variables might improve its prediction in COPD.
A total of 1,233 6-min walk tests and circulating proadrenomedullin (proADM) levels from 574 patients with clinically stable, moderate to very severe COPD enrolled in a multinational cohort study and followed up for 2 years were concomitantly analyzed.
The prevalence of exertional hypoxemia was 29.1%. In a matrix derived from a fitted-multistate model, the annual probability to develop exertional hypoxemia was 21.6%. Exertional hypoxemia was associated with greater deterioration of specific domains of health-related quality of life, higher severe exacerbation, and death annual rates. In the logistic linear and conditional Cox regression multivariable analyses, both FEV₁% predicted and proADM proved independent predictors of exertional hypoxemia (P < .001 for both). Adjustment for comorbidities, including cardiovascular disorders, and exacerbation rate did not influence results. Relative to using FEV₁% predicted alone, adding proADM resulted in a significant improvement of the predictive properties (P = .018). Based on the suggested nonlinear nomogram, patients with moderate COPD (FEV₁% predicted = 50%) but high proADM levels (> 2 nmol/L) presented increased risk (> 30%) for exertional desaturation.
Exertional desaturation is common and associated with poorer clinical outcomes in COPD. ADM improves prediction of exertional desaturation as compared with the use of FEV₁% predicted alone.
ISRCTN Register; No.: ISRCTN99586989; URL: www.controlled-trials.com
Evaluating nocturnal oxygen desaturation in COPD - Revised
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Citation Excerpt :
Although the definition of nocturnal oxygen desaturation (i.e., ≥30% of the recording time with an oxygen saturation < 90%) adopted in this study is arbitrary, it is nevertheless widely used, with some variation, in Canada21 and Europe.11 Given the absence of recommendations regarding the number of recordings and the night-to-nigh variability in nocturnal desaturation in COPD reported by Lewis et al.22, we elected to obtain 2 nocturnal recordings on each patient. This variability may be of importance when the time spent below a saturation < 90% approaches the diagnostic threshold.
Although in patients with COPD, the approach to daytime hypoxemia using long-term oxygen therapy (LTOT) is established, the best approach to transient nocturnal desaturation varies among clinicians. An understanding of the prevalence of nocturnal desaturation in COPD, in the absence of other respiratory co-morbidities, is an important step towards its standardized management.
We conducted a 5 site cross-sectional study of stable patients with COPD and mild-to-moderate daytime hypoxemia (PaO₂ 56–69 mmHg). Nocturnal saturation was monitored using home oximetry on 2 occasions over a 2-week period. Patients were classified in 3 categories: (A) no significant nocturnal desaturation; (B) significant nocturnal desaturation without evidence of sleep apnea; (C) significant nocturnal desaturation with evidence of sleep apnea.
In 128 patients (mean FEV₁: 37% predicted), we noted an excellent test-retest reliability between the 2 oximetries. Forty-nine patients (38%) were classified as nocturnal desaturators without evidence of sleep apnea, and 20 patients (16%) were classified as desaturators with evidence of sleep apnea. Nocturnal desaturation without sleep apnea could not be predicted by any patient characteristic or physiological measure.
A significant proportion (38%) of patients with moderate-to-severe COPD who do not qualify for home oxygen therapy based on their daytime PaO₂ have nocturnal oxygen desaturation without evidence of sleep apnea. Home oximetry is an effective practical method for screening this population.
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Between 2002 and 2005, consecutive patients with COPD attending outpatient services at the study centre underwent resting oximetry if they were not on domiciliary oxygen therapy. If their resting saturations were less than 95%, overnight pulse oximetry was performed. Significant nocturnal desaturation was defined as spending more than 30% of at least one of two nights with a saturation of less than 90%. The Chronic Respiratory Questionnaire (CRQ) and Short Form 36 (SF36) were used to assess HRQL, and the Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Score (ESS) and Functional Outcomes of Sleep (FOSQ) questionnaires were used to assess sleep quality and daytime function.
Of 1104 patients, 803 underwent resting oximetry and 79 had resting oxygen saturations of less than 95%. Of these, 59 agreed to undergo overnight oximetry (mean age 70 years, forced expiratory volume in 1 s 37.2% predicted, resting Po₂ on air 8.9 kPa). Significant nocturnal desaturation was seen in 29 (49.2%) of the 59 subjects. Assuming the less hypoxic patients do not have nocturnal desaturation, the prevalence of nocturnal desaturation in the whole clinic population could be estimated at 4.8%. There were no significant differences in CRQ, SF36, PSQI, ESS or FOSQ scores for desaturators compared with non-desaturators.
Significant nocturnal desaturation was common in patients with COPD with resting saturations of less than 95%, but was estimated to have a prevalence of less than 5% in the whole outpatient population. Nocturnal desaturation was not associated with impairment of HRQL, sleep quality or daytime function.
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: The study was performed at Green Lane Hospital, Auckland, New Zealand, and was supported by a research grant from the Asser Trust, Auckland.

: Dr. Lewis’ research fellowship was funded by a grant from GlaxoSmithKline New Zealand Ltd.

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Chest

Clinical InvestigationsSLEEP AND BREATHINGHome Overnight Pulse Oximetry in Patients With COPD: More Than One Recording May Be Needed

Study objectives:

Design:

Setting:

Patients:

Measurements and results:

Conclusion:

Section snippets

Subjects

Baseline Characteristics

Discussion

Conclusion

ACKNOWLEDGMENT

Lancet

Chest

Respir Med

Chest

Psychiatry Res

Nocturnal hypoxaemia in chronic obstructive pulmonary disease

Clin Sci

Nocturnal oxyhaemoglobin desaturation in COPD patients with arterial oxygen tensions above 60 mm Hg

Chest

Predictors for nocturnal hypoxaemia (mean Sa o2<90%) in normoxic and mildly hypoxic patients with COPD

Eur Respir J

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

Eur Respir J

A randomised trial of nocturnal oxygen therapy in chronic obstructive pulmonary disease patients

Eur Respir J

Clinical Investigations
SLEEP AND BREATHING
Home Overnight Pulse Oximetry in Patients With COPD: More Than One Recording May Be Needed

Predictors for nocturnal hypoxaemia (mean Sa o₂<90%) in normoxic and mildly hypoxic patients with COPD

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