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The Obesity-hypoventilation Syndrome Study of Clinical Characteristics and Predictive Factors of Response to Treatment

This study has been completed.
Spanish Respiratory Society
Information provided by:
Fundació Institut de Recerca de l'Hospital de la Santa Creu i Sant Pau Identifier:
First received: July 13, 2009
Last updated: NA
Last verified: July 2009
History: No changes posted

Main objective:

To describe clinical and functional characteristics of the obese hypoventilating patient; to study the relation between the obesity-hypoventilation syndrome (OHS) and the obstructive sleep apnea hypopnea syndrome (OSAHS). In the second stage of the study, to assess patient response to non-invasive mechanical ventilation (NIV) and continuous positive airway pressure (CPAP), and to identify predictors of unfavourable response to treatment.


  • Patients: Patients with obesity degree I-III, with pCO2 awake and at rest > 45 mmHg, with no underlying pulmonary or neuromuscular lung disease; two control groups, one of non-hypoventilating obese patients and the other of obese patients with OSAHS, will also be studied over the same period.
  • Design: Prospective observational study. In the first stage anthropometric, clinical, functional and metabolic data will be recorded for the obese hypoventilating patients and the two control groups (obese patients without respiratory pathology, and obese patients with OSAHS).

In the second stage patients with OHS will be divided into two subgroups: group 1: patients with polysomnography (PSG) suggestive of hypoventilation, in whom NIV treatment will be initiated; group 2: patients with PSG suggestive of OSAHS (apnea-hypopnea index >15), who will be administered CPAP. Patients will be examined one month and three months after the start of treatment. The same measurements will be carried out as at the beginning of the study, with the exception of the polysomnographic study. Nonetheless, pulse oximetry and arterial gases will be performed on waking.

Expected Results:

Patients with OHS may be characterized and differentiated from obese patients without associated respiratory pathology on the basis of clinical, functional and metabolic data.

There is a group of patients with association between OSAHS and OHS that do not respond to treatment with CPAP, and this unfavorable response can be predicted in advance.

Condition Intervention
Obesity Hypoventilation Syndrome
Device: CPAP
Device: Bilevel Support Ventilation (Non-Invasive Ventilation)

Study Type: Interventional
Study Design: Intervention Model: Single Group Assignment
Masking: Open Label
Primary Purpose: Treatment
Official Title: The Obesity-Hypoventilation Syndrome: A Study Of Clinical Characteristics And Predictive Factors Of Response To Treatment With Continuous Positive Airway Pressure (CPAP) And Non-Invasive Ventilation (NIV)

Further study details as provided by Fundació Institut de Recerca de l'Hospital de la Santa Creu i Sant Pau:

Enrollment: 110
Study Start Date: June 2003
Primary Completion Date: June 2006 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Active Comparator: CPAP
Response to treatment before/after treatment in patients with OSAS and SOH
Device: CPAP
Before and after effect of treatment with CPAP
Active Comparator: Bilevel support ventilation
Before and after effect of Bilevel support ventilation in patients with SOH without OSA
Device: Bilevel Support Ventilation (Non-Invasive Ventilation)
before/after effect of Bilevel support ventilation

  Show Detailed Description


Ages Eligible for Study:   18 Years to 75 Years   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • Obesity degree I-III (Body mass index, BMI >30 Kg/m2)
  • Stable daytime PCO2 >45 mmHg.
  • Age < 75 years
  • Absence of other parenchymal, respiratory or neuromuscular diseases, diseases of the chest wall which may occur concomitantly with hypoventilation.
  • Absence of exclusion criteria.

Exclusion Criteria:

  • Cognitive disorders that interfere with the administration of the clinical questionnaires.
  • Severe comorbidity.
  • FEV1/FVC ratio < 65% in the forced spirometry.
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Please refer to this study by its identifier: NCT00938977

Hospital de la Santa Creu i Sant Pau
BArcelona, Spain, 08025
Sponsors and Collaborators
Fundació Institut de Recerca de l'Hospital de la Santa Creu i Sant Pau
Spanish Respiratory Society
Principal Investigator: Neus Salord, MD Fundació Institut de Recerca de l'Hospital de la Santa Creu i Sant Pau
Study Chair: Mercedes Mayos, MD Fundació Institut de Recerca de l'Hospital de la Santa Creu i Sant Pau
  More Information

Publications automatically indexed to this study by Identifier (NCT Number):
Responsible Party: Neus Salord Oleo, Hospital de la Santa Creu i Sant Pau Identifier: NCT00938977     History of Changes
Other Study ID Numbers: HospitalSCSP
Study First Received: July 13, 2009
Last Updated: July 13, 2009

Keywords provided by Fundació Institut de Recerca de l'Hospital de la Santa Creu i Sant Pau:
Obesity Hypoventilation syndrome
continuous positive airway pressure
bilevel support ventilation
Response to continuous positive airway pressure

Additional relevant MeSH terms:
Obesity Hypoventilation Syndrome
Pathologic Processes
Nutrition Disorders
Body Weight
Signs and Symptoms
Respiratory Insufficiency
Respiration Disorders
Respiratory Tract Diseases
Signs and Symptoms, Respiratory
Sleep Apnea, Obstructive
Sleep Apnea Syndromes
Sleep Disorders, Intrinsic
Sleep Wake Disorders
Nervous System Diseases processed this record on April 28, 2017