A cohort study to identify simple clinical tests for chronic respiratory failure in obese patients with sleep-disordered breathing

Abstract

BackgroundChronic respiratory failure complicating sleep-disordered breathing in obese patients has important adverse clinical implications in terms of morbidity, mortality and healthcare utilisation. Screening strategies are essential to identify obese patients with chronic respiratory failure.MethodProspective data were collected from patients with obesity-related sleep-disordered breathing admitted for respiratory assessment at a UK national sleep and ventilation centre. Hypercapnia was defined as an arterial partial pressure of carbon dioxide of >6kPa.Results245 obese patients (56±13 years) with a body mass index of 48±12 kg/m2, forced vital capacity (FVC) of 2.1±1.1 L, daytime oximetry (SpO2) of 91±6% and abnormal overnight oximetry were included in the analysis. Receiver operator curve analysis for the whole group showed that an FVC ≤3 L had a sensitivity of 90% and a specificity of 41% in predicting hypercapnia, and an SpO2 ≤95% had a sensitivity of 83% and a specificity of 63% in predicting hypercapnia. Gender differences were observed and receiver operator curve analysis demonstrated ‘cut-offs’ for (1) SpO2 of ≤95% for men and ≤93% for women and (2) FVC of ≤3.5 L for men and ≤2.3 L for women, in predicting hypercapnia.ConclusionsThe measurement of FVC and clinic SpO2 in obese patients with abnormal overnight limited respiratory studies predicted hypercapnia. This may have clinical utility in stratifying patients attending sleep clinics.

Evaluation and Management of Obesity Hypoventilation Syndrome. An Official American Thoracic Society Clinical Practice Guideline

“…One of the four studies included a retrospective and prospective sample and provided diagnostic accuracy data for both samples at the cutoff of 27 mmol/L (40). Therefore, the pooled analysis includes five samples, with a total Nine studies evaluated hypoxemia by pulse oximetry (41,42,44,45,(47)(48)(49)(50)(51) and had prevalence of OHS between 17% and 66%. We identified 14 different measures of hypoxemia in these studies, including: awake oxygen saturation by pulse oximetry (Sp O 2 ) below a defined threshold (92-98%), sleep Sp O 2 below 90% for various percentages of sleep time (10-46%), nadir Sp O 2 during sleep below a defined threshold (76% or 80%), mean Sp O 2 during sleep below 90%, or a combination of Sp O 2 and bicarbonate level.…”

“…Of the remaining 13 articles we reviewed, 9 were full manuscripts ( 40 – 48 ) and 4 were in abstract form ( 49 – 52 ). Six were prospective ( 42 , 43 , 45 , 47 , 51 , 52 ), six were retrospective, and one had a retrospective and a prospective design ( 40 ).…”

Outcomes for Obese Patients with Chronic Respiratory Failure

“…Specifically, an FVC less than 3.5 L and a daytime clinic SpO 2 less than 95% in men and an FVC less than 2.3 L and an SpO 2 less than 93% in women predict a daytime P a CO 2 above 6 kPa or 45 mm Hg. 27 In part, these changes are reversible, with long-term treatment with NIV associated with improvements in the restrictive spirometric defect and static lung volumes, such as total lung capacity (TLC), FRC, and RV. 19,22 Drive to Breathe…”

Risks assessment of respiratory failure in patients before surgery

“…В рамках скрининга пациентов с целью выявления больных с высоким риском развития ПДО рекомендовано проводить оценку сатурации (SpO 2 ) при помощи пульсоксиметрии, показателей спирометрии, а также ночной оксиметрии. Десатурация кислорода, измеренная при помощи оксиметрии более чем на 4% не менее десяти событий в час, в сочетании со снижением сатурации, измеренной в дневные часы SpO 2 менее 95% у мужчин и 93% у женщин, а также снижение форсированной жизненной емкости легких (ФЖЕЛ) менее 3,5 л у мужчин и 2,3 л у женщин указывают на высокий риск развития послеоперационной дыхательной недоста-ОРИГИНАЛЬНЫЕ СТАТЬИ точности у данной категории больных [5]. Снижение показателей пикового потребления кислорода менее 15,8 мл/кг/мин и низкие показатели анаэробного порога у больных с ожирением также являются независимыми факторами риска развития ПДО и увеличения сроков пребывания больного в стационаре [6,7].…”