Effectiveness of different treatments in obesity hypoventilation syndrome.

Obesity hypoventilation syndrome (OHS) is an undesirable consequence of obesity, defined as daytime hypoventilation, sleep disorder breathing and obesity; during the past few years the prevalence of extreme obesity has markedly increased worldwide consequently increasing the prevalence of OHS. Patients with OHS have a lower quality of life and a higher risk of unfavourable cardiometabolic consequences. Early diagnosis and effective treatment can lead to significant improvement in patient outcomes; therefore, such data has noticeably raised interest in the management and treatment of this sleep disorder. This paper will discuss the findings on the main current treatment modalities OHS will be discussed.

[Obesity in childhood: What are the respiratory risks?] / Prise de poids chez l'enfant : quels risques respiratoires ?

In childhood and adolescence overweight is defined as a body mass index (BMI) above the 97th percentile for age and sex, according to the curves established by the International Obesity Task Force (IOTF). In France, it is estimated that 25 % of children under 18 years old are overweight. Overweight and obesity in this population are multifactorial, with an important influence of genetic factors, modulated by pre and post-natal (maternal smoking), societal and psychological determinants. The impact of obesity on respiratory function in children is mostly characterized by a decreased FEV1/FCV. Moreover, several studies have shown an association between asthma and overweight/obesity, with a pejorative impact of BMI on asthma control. However, asthma is still poorly characterized in this population, and the determinants of bronchial obstruction seem to differ from non-obese children, with less eosinophilic inflammation. Obstructive sleep apnea syndrome (OSAS) is a frequent complication of obesity, affecting up to 80% of obese children and adolescents. It has a specific polysomnographic definition in children. Symptoms are similar to adult OSAS, but with cognitive and neurobehavioral alterations often more important in adolescents. The treatment consists in ENT surgery when indicated (with systematic post-operative polysomnography), and nocturnal continuous positive airway pressure (CPAP). The obesity-hypoventilation syndrome (OHS) has the same definition in children as in adults and affects up to 20% of obese patients. Treatment consists in nocturnal ventilation using bilevel positive airway pressure (BiPAP). Finally, in some extreme cases, bariatric surgery can be performed. The indication should be discussed in a specialised paediatric reference centre.

[Preoperative risk and perioperative management of obese patients]. / Risque pré-opératoire et gestion péri-opératoire des patients obèses.

The obese patient is at an increased risk of perioperative complications. Most importantly, these include difficult access to the airways (intubation, difficult or impossible ventilation), and post-extubation respiratory distress secondary to the development of atelectasis or obstruction of the airways, sometimes associated with the use of morphine derivatives. The association of obstructive sleep apnea syndrome (OSA) with obesity is very common, and induces a high risk of peri- and postoperative complications. Preoperative OSA screening is crucial in the obese patient, as well as its specific management: use of continuous positive pre, per and postoperative pressure. For any obese patient, the implementation of protocols for mask ventilation and/or difficult intubation and the use of protective ventilation, morphine-sparing strategies and a semi-seated positioning throughout the care, is recommended, combined with close monitoring postoperatively. The dosage of anesthetic drugs should be based on the theoretical ideal weight and then titrated, rather than dosed to the total weight. Monitoring of neuromuscular blocking should be used where appropriate, as well as monitoring of the depth of anesthesia. The occurrence of intraoperative recall is indeed more frequent in the obese patient than in the non-obese patient. Appropriate prophylaxis against venous thromboembolic disease and early mobilization are recommended, as thromboembolic disease is increased in the obese patient. The use of non-invasive ventilation to prevent the occurrence of acute post-operative respiratory failure and for its treatment is particularly effective in obese patients. In case of admission to ICU, an individualized ventilatory management based on pathophysiology and careful monitoring should be initiated.

Obesity-hypoventilation syndrome and associated factors. / Síndrome de obesidad-hipoventilación y factores asociados.

BACKGROUND AND OBJECTIVES: Obesity causes important alterations in the respiratory physiology like sleep obstructive apnoea (SOA) and obesity-hypoventilation syndrome (OHS), both associated with high morbidity and mortality. Also, these entities are clearly infradiagnosed and in the case of OHS the prevalence is unknown in the general obese population. To determine the prevalence of OHS in the population of patients with morbid obesity and to know the comorbidity related with OHS, the associated respiratory symptoms and the pulse oximetry alterations. PATIENTS AND METHOD: Descriptive study. Selection of 136 adult patients with morbid obesity (BMI >40). Collected were, anthropometric data, toxic habits, concomitant disease, symptom data, analytic data, dyspnoea grade, sleepiness scale (Epworth Test), electrocardiogram, chest X-ray, spirometry, nocturne ambulatory pulse oximetry and arterial gasometry. RESULTS: 136 were studied, mean age 60 years old (SD 12.9 years), 73% (98) were women; 6.6% of patients presented diurnal hypercapnia indicative of OHS; 72% presented high blood pressure, 44% dyslipidaemia, 18% presented cardiovascular disease, 83% snored and 46% had apnoea; 30% presented stageII dyspnoea and 10% stageIII. The desaturation/hour index was above 3% ≥30 of occasions in 28.6% of patients and the percentage of patients with saturations <90% more than 30% of the time was 23.5%. The results were worse in patients with OHS. CONCLUSIONS: The prevalence of OHS was lower than expected. Noteworthy was the high comorbidity of cardiovascular disease and the high frequency of respiratory symptoms associated with important alterations of pulse oximetry.

Non-invasive ventilation for sleep-disordered breathing in Smith-Magenis syndrome.

Smith-Magenis syndrome (SMS) is a rare genetic neurodevelopmental disorder characterised by behavioural disturbances, intellectual disability and early onset obesity. The physical features of this syndrome are well characterised; however, behavioural features, such as sleep disturbance, are less well understood and difficult to manage. Sleep issues in SMS are likely due to a combination of disturbed melatonin cycle, facial anatomy and obesity-related ventilatory problems. Sleep disorders can be very distressing to patients and their families, as exemplified by our patient's experience, and can worsen behavioural issues as well as general health. This case demonstrates the successful use of non-invasive ventilation in treating underlying obesity hypoventilation syndrome and obstructive sleep apnoea. As a consequence of addressing abnormalities in sleep patterns, some behavioural problems improved.

Obesity hypoventilation syndrome: current theories of pathogenesis.

PURPOSE OF REVIEW: To summarize recent primary publications and discuss the impact these finding have on current understanding on the development of hypoventilation in obesity hypoventilation syndrome (OHS), also known as Pickwickian syndrome. RECENT FINDINGS: As a result of the significant morbidity and mortality associated with OHS, evidence is building for pre-OHS intermediate states that can be identified earlier and treated sooner, with the goal of modifying disease course. Findings of alterations in respiratory mechanics with obesity remain unchanged; however, elevated metabolism and CO2 production may be instrumental in OHS-related hypercapnia. Ongoing positive airway pressure trials continue to demonstrate that correction of nocturnal obstructive sleep apnea and hypoventilation improves diurnal respiratory physiology, metabolic profiles, quality of life, and morbidity/mortality. Finally, CNS effects of leptin on respiratory mechanics and chemoreceptor sensitivity are becoming better understood; however, characterization remains incomplete. SUMMARY: OHS is a complex multiorgan system disease process that appears to be driven by adaptive changes in respiratory physiology and compensatory changes in metabolic processes, both of which are ultimately counter-productive. The diurnal hypercapnia and hypoxia induce pathologic effects that further worsen sleep-related breathing, resulting in a slowly progressive worsening of disease. In addition, leptin resistance in obesity and OHS likely contributes to blunting of ventilatory drive and inadequate chemoreceptor response to hypercarbia and hypoxemia.

A case of obesity hypoventilation syndrome with respiratory failure that improved with abdominoplasty.

We report on a 70-year-old man with severe respiratory failure caused by obesity hypoventilation syndrome due to abdominal adiposis. Obesity hypoventilation syndrome is a severe condition that is diagnosed when all of the following criteria are satisfied: body-mass index >30 kg/m(2); apnea hypopnea index >30; PaCO2 >45 mm Hg (in the daytime); and marked daytime somnolence. Abdominoplasty, which is generally used for abdominal laxness, striae, and rectus muscle diastases and for women in the postpartum period, was performed for this patient to facilitate ventilator weaning and produced a satisfactory result.

Clinical predictors of obesity hypoventilation syndrome in obese subjects with obstructive sleep apnea.

BACKGROUND: Arterial blood gas (ABG) analysis is not a routine test in sleep laboratories due to its invasive nature. Therefore, the diagnosis of obesity hypoventilation syndrome (OHS) is underestimated. We aimed to evaluate the differences in subjects with OHS and pure obstructive sleep apnea (OSA) and to determine clinical predictors of OHS in obese subjects. METHODS: Demographics, body mass index (BMI), Epworth Sleepiness Scale score, polysomnographic data, ABG, spirometric measurements, and serum bicarbonate levels were recorded. RESULTS: Of 152 obese subjects with OSA (79 females/73 males, mean age of 50.3 ± 10.6 y, BMI of 40.1 ± 5.6 kg/m(2), 51.9% with severe OSA), 42.1% (n = 64) had OHS. Subjects with OHS had higher BMI (P = .02), neck circumference (P < .001), waist circumference (P < .001), waist/hip ratio (P = .02), Epworth Sleepiness Scale scores (P = .036), ABG and serum bicarbonate levels (P < .001), apnea-hypopnea index (P = .01), oxygen desaturation index (P < .001), and total sleep time with S(pO2) < 90% (P < .001) compared with subjects with pure OSA (n = 88). They also had lower daytime PaO2 (P < .001), sleep efficiency (P = .032), mean S(pO2) (P < .001), and nadir S(pO2) (P < .001). Serum bicarbonate levels and nadir S(pO2) were the only independent predictive factors for OHS. A serum bicarbonate level of ≥ 27 mmol/L as the cutoff gives a satisfactory discrimination for the diagnosis of OHS (sensitivity of 76.6%, specificity of 74.6%, positive predictive value of 54.5%, negative predictive value of 88.9%). A nadir S(pO2) of < 80% as the cutoff gives a satisfactory discrimination for the diagnosis of OHS (sensitivity of 82.8%, specificity of 54.5%, positive predictive value of 56.9%, negative predictive value of 81.4%). When we used a serum bicarbonate level of ≥ 27 mmol/L and/or a nadir S(pO2) of < 80% as a screening measure, only 3 of 64 subjects with OHS were missed. CONCLUSIONS: Serum bicarbonate level and nadir saturation were independent predictive factors for the diagnosis of OHS.

Early and long-term clinical outcomes of bilio-intestinal diversion in morbidly obese patients.

PURPOSE: To evaluate the early and long-term postoperative results of malabsorptive surgery in morbidly obese patients. METHODS: Between 2000 and 2007, 102 morbidly obese patients were referred to the Department of Surgery "Pietro Valdoni", "Sapienza" University of Rome, Policlinico "Umberto I°", Rome, Italy for malabsorptive surgery. All patients underwent derivative biliodigestive surgery after they had been reviewed by a team of surgeons, physicians, dieticians, and psychologists. RESULTS: There were no intra-operative complications, but two patients suffered postoperative pulmonary embolisms, which resolved with medical treatment. The mean postoperative hospital stay was 7 days, with no early or late mortality. Maximum weight loss was reached 12-24 months after surgery, while the mean percentage excess weight loss at 3-5 years ranged from 45 to 64 %. Specific postoperative complications in the first 2 years after surgery were abdominal abscess (n = 2), gastroduodenal reflux (n = 4), and incisional hernia (n = 6). Diabetes resolved in 98 % of the diabetic patients within a few weeks after surgery and blood pressure normalised in 86.4 % of those who had had hypertension preoperatively. Obstructive sleep apnoea and obesity hypoventilation syndrome also improved significantly in 92 % of the patients. CONCLUSIONS: Morbidly obese patients can undergo biliodigestive surgery safely with good long-term weight loss and quality of life expectancy.

Obesity and sleep-disordered breathing--when two 'bad guys' meet.

Sleep-disordered breathing (SDB), in particular obstructive sleep apnoea (OSA) and obesity hypoventilation syndrome (OHS) are associated with significant morbidity and mortality. The prevalence of these conditions is rapidly rising mainly due to the worldwide increase in obesity. Obesity contributes to the pathogenesis of SDB in multiple ways including altering upper airway anatomy and collapsibility, ventilatory control and increasing respiratory work load. There is also increasing evidence that OSA itself contributes to the development of obesity. Moreover, both OSA and obesity promote the activation of inflammatory pathways, which is likely a key mechanism in cardiovascular and metabolic disease processes. Early recognition of SDB is important as effective treatments are available. Public health measures to reduce the prevalence of obesity are urgently required to halt the increasing burden of SDB.

Chronic hypoventilation and its management.

While obstructive sleep apnoea syndrome dominates discussion of the prevalence of sleep disordered breathing, nocturnal hypoventilation remains extremely prevalent in those with chronic ventilatory disorders and in the natural history of these conditions pre-dates the development of daytime ventilatory failure. In this review the clinical management of chronic hypoventilation in neuromuscular disease will be considered and then compared with that in obesity hypoventilation syndrome. In simple terms these conditions illustrate the polar opposite ends of the spectrum, as in neuromuscular disease the reduced capacity of the respiratory system is unable to withstand a normal respiratory load, and in obesity hypoventilation syndrome the normal capacity of the respiratory system is unable to tolerate a substantially increased ventilatory load.

Diagnostic predictors of obesity-hypoventilation syndrome in patients suspected of having sleep disordered breathing.

INTRODUCTION: Obesity-hypoventilation syndrome (OHS) is associated with significant morbidity and mortality and requires measurement of arterial pCO2 for diagnosis. OBJECTIVE: To determine diagnostic predictors of OHS among obese patients with suspected obstructive sleep apnea/hypopnea syndrome (OSAHS). METHODS: Retrospective analysis of data on 525 sleep clinic patients (mean age 51.4 ± 12.7 years; 65.7% males; mean BMI 34.5 ± 8.1). All patients had sleep studies, and arterialized capillary blood gases (CBG) were measured in obese subjects (BMI > 30 kg/m2). RESULTS: Of 525 patients, 65.5% were obese, 37.2% were morbidly obese (BMI > 40 kg/m2); 52.3% had confirmed OSAHS. Hypercapnia (pCO2 > 6 kPa or 45 mm Hg) was present in 20.6% obese and 22.1% OSAHS patients. Analysis of OHS predictors showed significant correlations between pCO2 and BMI, FEV1, FVC, AHI, mean and minimum nocturnal SpO2, sleep time with SpO2 < 90%, pO2, and calculated HCO3 from the CBG. PO2 and HCO3 were independent predictors of OHS, explaining 27.7% of pCO2 variance (p < 0.0001). A calculated HCO3 cutoff > 27 mmol/L had 85.7% sensitivity and 89.5% specificity for diagnosis of OHS, with 68.1% positive and 95.9% negative predictive value. CONCLUSION: We confirmed a high prevalence of OHS in obese OSAHS patients (22.1%) and high calculated HCO3 level (> 27 mmol/L) to be a sensitive and specific predictor for the diagnosis of OHS.

The malignant obesity hypoventilation syndrome (MOHS).

We have coined the term 'malignant obesity hypoventilation syndrome' (MOHS) to describe a severe multisystem disease due to the systemic effects of obesity. Patients with this syndrome have severe obesity-related hypoventilation together with systemic hypertension, diabetes and the metabolic syndrome, left ventricular hypertrophy with diastolic dysfunction, pulmonary hypertension and hepatic dysfunction. This syndrome is largely unrecognized as physicians do not make the association between the patients' multiple medical problems and obesity. Because of the delayed diagnosis and progressive morbidities of this condition, all patients with a body mass index of more than 40 kg m(-2) should be screened for MOHS. The management of patients with MOHS includes short-term measures to improve the patients' medical condition and long-term measures to achieve enduring weight loss. Bariatric surgery reverses or improves the multiple metabolic and organ dysfunctions associated with MOHS and should be strongly considered in these patients.

The complex spectrum of forensic issues arising from obesity.

The increasing numbers of obese and morbidly obese individuals in the community are having a direct effect on forensic facilities. In addition to having to install more robust equipment for handling large bodies, the quality of autopsy examinations may be reduced by the physical difficulties that arise in trying to position bodies correctly so that normal examinations can proceed. Accelerated putrefaction is often an added complication. Metabolic disturbances resulting from obesity increase susceptibility to a range of conditions that are associated with sudden and unexpected death, and surgery may have increased complications. The rates of a number of different malignancies, including lymphoma, leukemia, melanoma and multiple myeloma, and carcinomas of the esophagus, stomach, colon, gallbladder, thyroid, prostate, breast and endometrium, are increased. In addition, obese individuals have higher rates of diabetes mellitus, and sepsis. The unexpected collapse of an obese individual should raise the possibility of a wide range of conditions, many of which may be more difficult to demonstrate at autopsy than in an individual with a normal body mass index. Although sudden cardiac death due to cardiomegaly, pulmonary thromboembolism, or ischemic heart disease may be the most probable diagnosis in an unexpected collapse, the range of possible underlying conditions is extensive and often only determinable after full postmortem examination.

[Obesity and sleep-related breathing disorders].

Obesity, with an increasing prevalence,has become one of the most common metabolic diseases. Obesity is associated with many respiratory diseases, especially sleep-related breathing disorders including obstructive sleep apnea-hypopnea syndrome, obesity hypoventilation syndrome, and overlap syndrome. This article reviews the association between obesity and these sleep-related breathing disorders.