Obstructive Sleep Apnea, Obesity Hypoventilation Syndrome, and Pulmonary Hypertension: A State-of-the-Art Review

The pathophysiological interplay between sleep-disordered breathing (SDB) and pulmonary hypertension (PH) is complex and can involve a variety of mechanisms by which SDB can worsen PH. These mechanistic pathways include wide swings in intrathoracic pressure while breathing against an occluded upper airway, intermittent and/or sustained hypoxemia, acute and/or chronic hypercapnia, and obesity. In this review, we discuss how the downstream consequences of SDB can adversely impact PH, the challenges in accurately diagnosing and classifying PH in the severely obese, and review the limited literature assessing the effect of treating obesity, obstructive sleep apnea, and obesity hypoventilation syndrome on PH.

[Treatment and long-term follow-up of obesity hypoventilation syndrome]

Bevezetés: Az obesitas-hypoventilatiós szindróma (OHS) a tartós otthoni noninvazív légzéstámogatás leggyakoribb indikációja világszerte. Magyarországon ma még kevés adat áll rendelkezésre előfordulásáról és kimeneteléről, bár a tartós otthoni lélegeztetés finanszírozási és terápiás lehetőségei közel egy évtizede elérhetők. Célkitűzés: Vizsgálatunk célja az volt, hogy a Semmelweis Egyetem Otthoni Lélegeztetési Programjában gondozott OHS-páciensek rövid és hosszú távú klinikai mutatóit elemezzük, különös tekintettel a betegek hosszú távú túlélésére. Módszer: Prospektív vizsgálatunk során azokat az OHS-pácienseket követtük nyomon, akik esetében a tartós légzéstámogatás 2018. 01. 01. és 2023. 01. 30. között indult. Eredmények: A vizsgálatba 63 OHS-beteget vontunk be. A hosszú távú légzéstámogatás 25 (40%) esetben elektíven, 38 (60%) esetben pedig akut légzési elégtelenség kezelését követően került beállításra. 6 hónap lélegeztetésterápiát követően a betegek 96,83%-a (61 páciens) jó együttműködést mutatott a terápiával. A kontrollvizsgálat adatai alapján a betegek átlagosan napi 7,49 (± 2,92) órát használták a noninvazív lélegeztetőgépet, és 54 páciens (86%) esetében elérhető volt a normocapnia. A 63 beteg teljes gondozási ideje a megfigyelési időszak (67 hónap) alatt átlagosan 32,51 (± 18,45) hónap volt, és 6 hónaptól 66 hónapig terjedt. Számításunk alapján a vizsgálatban részt vevők 5 éves kumulatív túlélése 86% volt. Következtetés: Az OHS-betegek a protokoll szerinti, célorientált tartós légzéstámogatás mellett igen jó klinikai eredményekre és a nemzetközi irodalmi adatokhoz képest is kiemelkedő túlélésre számíthatnak. Orv Hetil. 2024; 165(10): 385–392.

The assessment and management of obstructive sleep apnoea-hypopnoea syndrome and obesity hypoventilation syndrome in obesity

Obesity is associated with respiratory dysfunction. It is a key risk and contributory factor in the sleep related breathing disorders, obstructive sleep apnoea/hypopnoea syndrome (OSAHS) and obesity hypoventilation syndrome (OHS). Weight management is an integral part of the management of these disorders, in addition to continuous positive airways pressure (CPAP) and non-invasive ventilation (NIV). Untreated, these conditions are associated with a high disease burden and as treatment is effective, early recognition and referral is critical. Best practice in on-going care is multidisciplinary.

A Novel Nomogram and Online Calculator for Predicting the Risk of Obesity Hypoventilation Syndrome in Bariatric Surgery Candidates

BACKGROUND

Obesity hypoventilation syndrome (OHS) is frequently misdiagnosed and undertreated, increasing the risk of perioperative complications. We aimed to determine the predictors of OHS and to develop and validate a novel nomogram and online calculator for identifying patients at risk of OHS in bariatric surgery candidates.

METHODS

We retrospectively analyzed the data of patients undergoing bariatric surgery between March 2017 and June 2020. Predictors were identified using univariate and multivariate analyses to establish the nomogram. The discriminative ability, calibration, and clinical value of the nomograms were tested using C-statistics, calibration plots, and decision curve analysis. The nomogram was internally validated using bootstrap resampling.

RESULTS

A total of 577 patients were enrolled, and OHS was presented in 17.9% (103/577). Body mass index (BMI) (odds ratio [OR], 1.11; 95% confidence interval (CI), 1.04-1.18; p = 0.001), neck circumference (OR, 1.09; 95% CI, 1.01-1.18; p = 0.035), type 2 diabetes (T2D) (OR, 2.02; 95% CI, 1.17-3.45; p = 0.011), serum bicarbonate (OR, 1.47; 95% CI, 1.30-1.67; p < 0.001), and C-reactive protein (CRP) (OR, 1.03; 95% CI, 1.01-1.06; p = 0.017) were independent risk factors for OHS and incorporated to develop the nomogram. The nomogram revealed good discrimination, with a C-index of 0.830 (95% CI: 0.784-0.876) (0.8227 through internal validation), and good calibration. Decision curve analysis further confirmed the nomogram's clinical usefulness.

CONCLUSIONS

The novel nomogram and online calculator provided an excellent preoperative individualized prediction of OHS in patients undergoing bariatric surgery, hereby potentially assisting clinicians and surgeons in the early detection and intensive monitoring of OHS.

A novel case of central hypoventilation syndrome or just heavy breathing?

With the growing prevalence of obesity in the pediatric population, reports of its severe complications are increasing. Obesity hypoventilation syndrome is an uncommon disorder in children with altered respiratory mechanics, sleep-disordered breathing, and impaired ventilatory responses leading to persistent hypercapnia. Presentation is varied, and children may remain relatively asymptomatic until challenged with a respiratory infection, when they may present with acute respiratory failure. With increasing use of genetic testing in pediatric patients, our knowledge of potential contributors to hypoventilation syndromes is growing. Although mutations in the paired-like homeobox 2B gene are known to be causative of congenital central hypoventilation syndrome, other genes may also contribute to hypoventilation phenotypes. We report one of the youngest reported patients with obesity hypoventilation syndrome in pediatrics, with a proposed congenital predisposition for central hypoventilation derived from a deletion in the brain-derived neurotrophic factor gene.

CITATION

McCoy J, Karp N, Brar J, Amin R, St-Laurent A. A novel case of central hypoventilation syndrome or just heavy breathing? J Clin Sleep Med. 2022;18(9):2321-2325.

Extubating to Noninvasive Ventilation: Noninvasive Ventilation from Intensive Care Unit to Home

Weaning to noninvasive ventilation in intensive care unit and bridging the patients to home with respiratory support is evolving as the technology of noninvasive ventilation is improving. In patients with chronic obstructive pulmonary disease exacerbation, timing of initiation of noninvasive ventilation is the key, as persistently hypercapnic patients show benefits. High-intensity pressure support seems to do better in comparison to low-intensity pressure support. In patients with obesity and hypercapnia, obesity hypoventilation cannot be ruled out especially in an inpatient setting, and it is crucial that these patients are discharged with noninvasive ventilation.

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

Background: The purpose of this guideline is to optimize evaluation and management of patients with obesity hypoventilation syndrome (OHS).

Methods: A multidisciplinary panel identified and prioritized five clinical questions. The panel performed systematic reviews of available studies (up to July 2018) and followed the Grading of Recommendations, Assessment, Development, and Evaluation evidence-to-decision framework to develop recommendations. All panel members discussed and approved the recommendations.

Recommendations: After considering the overall very low quality of the evidence, the panel made five conditional recommendations. We suggest that: 1) clinicians use a serum bicarbonate level <27 mmol/L to exclude the diagnosis of OHS in obese patients with sleep-disordered breathing when suspicion for OHS is not very high (<20%) but to measure arterial blood gases in patients strongly suspected of having OHS, 2) stable ambulatory patients with OHS receive positive airway pressure (PAP), 3) continuous positive airway pressure (CPAP) rather than noninvasive ventilation be offered as the first-line treatment to stable ambulatory patients with OHS and coexistent severe obstructive sleep apnea, 4) patients hospitalized with respiratory failure and suspected of having OHS be discharged with noninvasive ventilation until they undergo outpatient diagnostic procedures and PAP titration in the sleep laboratory (ideally within 2–3 mo), and 5) patients with OHS use weight-loss interventions that produce sustained weight loss of 25% to 30% of body weight to achieve resolution of OHS (which is more likely to be obtained with bariatric surgery).

Conclusions: Clinicians may use these recommendations, on the basis of the best available evidence, to guide management and improve outcomes among patients with OHS.

Obesity hypoventilation syndrome

Obesity hypoventilation syndrome (OHS) is defined as a combination of obesity (body mass index ≥30 kg·m-2), daytime hypercapnia (arterial carbon dioxide tension ≥45 mmHg) and sleep disordered breathing, after ruling out other disorders that may cause alveolar hypoventilation. OHS prevalence has been estimated to be ∼0.4% of the adult population. OHS is typically diagnosed during an episode of acute-on-chronic hypercapnic respiratory failure or when symptoms lead to pulmonary or sleep consultation in stable conditions. The diagnosis is firmly established after arterial blood gases and a sleep study. The presence of daytime hypercapnia is explained by several co-existing mechanisms such as obesity-related changes in the respiratory system, alterations in respiratory drive and breathing abnormalities during sleep. The most frequent comorbidities are metabolic and cardiovascular, mainly heart failure, coronary disease and pulmonary hypertension. Both continuous positive airway pressure (CPAP) and noninvasive ventilation (NIV) improve clinical symptoms, quality of life, gas exchange, and sleep disordered breathing. CPAP is considered the first-line treatment modality for OHS phenotype with concomitant severe obstructive sleep apnoea, whereas NIV is preferred in the minority of OHS patients with hypoventilation during sleep with no or milder forms of obstructive sleep apnoea (approximately <30% of OHS patients). Acute-on-chronic hypercapnic respiratory failure is habitually treated with NIV. Appropriate management of comorbidities including medications and rehabilitation programmes are key issues for improving prognosis.

[Asthma and obesity : preventable therapeutic trap, with careful follow-up]

Nowadays, more and more obese asthmatics visit a pulmonologist. It is proven that overweight stirs up the severity of the bronchopathy. It is a concept that is now anchored in the minds of most modern practitioners. Nevertheless, the idea that in some patients, excess weight can be an independent cause of the persistence of respiratory complaints, is sometimes neglected. This case report is about a severely obese poorly controlled asthmatic man, who turns out to be suffering from a concomitant obesity-hypoventilation syndrome. His clinical history confirms the necessity of quickly detecting this restrictive syndrome within an obstructive background, before its evolution towards a severe acute respiratory failure, where therapeutic approximations can have dramatic repercussions on the patient's health.

[Obesity hypoventilation syndrome and pulmonary hypertension. An association little-known in Mexico]

The obesity hypoventilation syndrome (OHS) refers to the combination of obesity, daytime hypercapnia and sleep-disordered breathing. Obesity has risen to epidemic proportions in the last three decades in the United States, Mexico and Europe. The OHS is associated with obstructive sleep apnea syndrome in 30%. Without treatment, mortality is 46% at 50 months. So in this paper we analyze the OHS, obesity and pulmonary hypertension, the pathophysiology, clinical presentation and diagnosis as well as the treatment, which is aimed at the correction of sleep-disordered breathing and hypoxemia; although there is little experience with the use of specific pulmonary vasodilator drugs.

Rapid-onset obesity, hypothalamic dysfunction, hypoventilation, and autonomic dysregulation in Saudi Arabia

Rapid-onset obesity, hypothalamic dysfunction, hypoventilation, and autonomic dysregulation (ROHHAD) is a rare disease, but could be fatal if not diagnosed early. It mimics many other diseases and it may take few years after the onset of rapid obesity to have the other clinical features. Therefore, any patient with rapid-onset obesity after the age of 2 years should have high index of suspicion and long term follow up. We report a case of ROHHAD in Saudi Arabia and we highlight the clinical features and the importance of early diagnosis and management.

Respiratory Conditions Update: Restrictive Lung Disease

Restrictive lung diseases are a heterogeneous group of conditions characterized by a restrictive pattern on spirometry and confirmed by a reduction in total lung volume. Patients with more severe symptoms may have a reduced diffusing capacity of the lung for carbon monoxide. Etiologies can be intrinsic with lung parenchymal involvement, as in interstitial lung diseases, or extrinsic to the lung, as in obesity and neuromuscular disorders. Idiopathic pulmonary fibrosis is a chronic progressive interstitial pneumonia with fibrosis for which treatment is primarily supportive with oxygen therapy, pulmonary rehabilitation, and management of comorbid conditions. Newer drugs for idiopathic pulmonary fibrosis, such as pirfenidone and nintedanib, can slow disease progression. Referral for evaluation for lung transplantation is recommended for appropriate patients. Obstructive sleep apnea and obesity hypoventilation syndrome increasingly are common health issues, with symptoms that can include snoring, daytime somnolence, difficulty concentrating, fatigue, witnessed apneas, and morning headaches. Serum bicarbonate may serve as a biomarker in screening for subclinical obesity hypoventilation syndrome. Preoperative evaluations should assess pulmonary risk in addition to cardiac risk with a thorough history, laboratory tests, and functional capacity assessments. Optimization of management may include weight loss, pulmonary rehabilitation, oxygen therapy, and respiratory support.

Rapid-onset obesity with hypothalamic dysregulation, hypoventilation, and autonomic dysregulation (ROHHAD syndrome): A case report and literature review

INTRODUCTION

ROHHAD syndrome (rapid-onset obesity with hypothalamic dysregulation, hypoventilation, and autonomic dysregulation) is a rare and complex disease, presenting in previously healthy children at the age of 2-4 years. Up to 40% of cases are associated with neural crest tumours.

DEVELOPMENT

We present the case of a 2-year-old girl with symptoms of rapidly progressing obesity, who a few months later developed hypothalamic dysfunction with severe electrolyte imbalance, behaviour disorder, hypoventilation, and severe autonomic dysregulation, among other symptoms. Although the pathophysiology of this syndrome remains unclear, an autoimmune hypothesis has been proposed for ROHHAD. Therefore, after obtaining a limited response to intravenous immunoglobulins, we decided to test the response to a high dose cyclophosphamide (low dose was not effective either). Unfortunately our patient experienced many severe complications (among them central pontine myelinolysis, from which the patient recovered, and failure to wean from the ventilator requiring tracheostomy and long term ventilation) that required a prolonged ICU stay. Although her behaviour improved, our patient unfortunately died suddenly at home at the age of 5 due to respiratory pathology.

CONCLUSIONS

ROHHAD syndrome is a rare and little-known disease which requires a multidisciplinary approach because it involves complex symptoms and multiple organ system involvement. Alveolar hypoventilation should be identified early and appropriate treatment should be started promptly for the best possible outcome. Immunomodulatory treatment with immunoglobulins, cyclophosphamide, or rituximab has previously resulted in symptom improvement in some cases. Because of the low incidence of the syndrome, multi-centre studies must be carried out in order to gather more accurate information about ROHHAD pathophysiology and design an appropriate therapeutic approach.

[Efficient treatment of chronic respiratory failure associated with morbid obesity]

Severe obesity sometimes leads to chronic respiratory failure. This condition is termed obesity-hypoventilation or Pickwickian syndrome. This article reports clinical observation illustrating effectiveness of noninvasive pressure support ventilation for the treatment of hypercapnic respiratory failure in a patient with morbid obesity. The treatment strategies for such patients are discussed.

Hypoventilation syndromes

The hypoventilation syndromes represent a variety of disorders that affect central ventilatory control, respiratory mechanics, or both. Obesity hypoventilation syndrome is a clinically important disorder with serious cardiovascular and metabolic consequences if unrecognized. Hypoventilation in asthma and COPD is caused by mechanical challenges imparted by airflow obstruction and increase in dead space. In neuromuscular disease, respiratory muscle weakness results in hypoventilation. Decreases in thoracic volume and limited expansion of the chest highlight the restrictive ventilatory impairments seen in hypoventilation associated with chest wall disorders. Despite the mechanism, effective hypoventilation treatment targets the underlying disease and use of noninvasive ventilation.

Obesity hypoventilation syndrome: prevalence and predictors in patients with obstructive sleep apnea

Patients with obesity hypoventilation syndrome (OHS) have a lower quality of life, more healthcare expenses, a greater risk of pulmonary hypertension, and a higher mortality compared to eucapnic patients with obstructive sleep apnea (OSA). Despite significant morbidity and mortality associated with OHS, it is often unrecognized and treatment is frequently delayed. The objective of this observational study was to determine the prevalence of OHS in patients with OSA seen at the sleep disorders clinic of a large public urban hospital serving predominantly minority population and to identify clinical--not mechanistic--predictors that should prompt clinicians to measure arterial blood gases. In the first stage, we randomly selected 180 patients referred to our sleep disorders clinic between 2000 and 2004 for suspicion of OSA. From this retrospective random sample we calculated the prevalence of OHS in patients with OSA and identified independent clinical predictors using logistic regression. In the second stage, we prospectively validated these predictors in a sample of 410 consecutive patients referred to the sleep disorders clinic for suspicion of OSA between 2005 and 2006. The prevalence of OHS in patients with OSA was 30% in the retrospective random sample and 20% in the prospective sample. Three variables independently predicted OHS in both samples: serum bicarbonate level (p < 0.001), apnea-hypopnea index (p = 0.006), and lowest oxygen saturation during sleep (p < 0.001). Due to the serious morbidity associated with OHS, we selected a highly sensitive threshold of serum bicarbonate level. A threshold of 27 mEq/l had a sensitivity of 92% and a specificity of 50%. Only 3% of patients with a serum bicarbonate level <27 mEq/l had hypercapnia compared to 50% with a serum bicarbonate > or =27 mEq/l. In conclusion, OHS is common in severe OSA. A normal serum bicarbonate level excludes hypercapnia and an elevated serum bicarbonate level should prompt clinicians to measure arterial blood gases.

Clinical Heterogeneity among Patients with Obesity Hypoventilation Syndrome: Therapeutic Implications

BACKGROUND

Obesity hypoventilation syndrome (OHS) can be treated with noninvasive positive pressure ventilation (NIPPV). Once clinical stability is achieved, continuous positive airway pressure (CPAP) can be recommended in many cases. However, some patients respond only partially to CPAP and NIPPV is a better option for them.

OBJECTIVES

To assess treatment effectiveness in 2 groups of patients: those who could be switched to CPAP after polysomnographic titration and those who required NIPPV.

METHODS

A prospective study of 24 OHS patients was conducted, 11 were treated with CPAP and 13 with NIPPV. Morning and evening arterial blood gases were measured. Daytime and overnight oximetric recordings were performed. A post hoc analysis compared both groups.

RESULTS

Neither group exhibited deterioration on morning-to-evening blood gases. All patients in the CPAP group presented SaO(2) of less than 90% (CT90%) for <15% of the time on nocturnal and daytime recordings. In the NIPPV group, 8 patients had either daytime or nocturnal CT90% >or=15%. There were no intergroup differences regarding age, body mass index, Epworth scale values or PaO(2)/PaCO(2) prior to treatment. FVC in the NIPPV group was lower than in the CPAP group (p = 0.01). Apnea-hypopnea index was higher (56 +/- 23 vs. 36 +/- 23, p = 0.049) and baseline CT90% was lower (76 +/- 19% vs. 92 +/- 14%, p = 0.03) in the CPAP group.

CONCLUSIONS

Two patient subtypes can be identified. Those controlled with CPAP have better spirometry and a significantly higher apnea-hypopnea index. None of these patients showed daytime hypoxemia and all exhibited satisfactory overnight oxygenation. However, 61% of the NIPPV group had suboptimal oximetry results. Nocturnal/diurnal oximetries should be made to assess treatment efficacy in stable OHS patients who fail to achieve good control with CPAP.

[Obesity in adolescents: physical correlated pathologies, and therapeutic state of art]

Obese adolescents are prone to several pathologies, which may begin in this period of life and have a continuity in adult age. In this review the author tries first to explain the obesity definition in infants, children, and adolescents. Some pathologies may appear in adolescent age. First of all, some features of the so called metabolic syndrome; furthermore, hormonal alteration during and after puberty, genital appearance in the obese adolescent male, respiratory problems as apnea, asthma, and the Pickwick syndrome. The non alcoholic fat liver disease is also described, and the orthopedic problems as well, owing to the overweight: from abnormal body posture to structural consequences on the skeleton. Finally, some remarks concerning pharmacological and surgical approach are presented.

Treatment refractory psychosis remitted upon treatment with continuous positive airway pressure: a case report

INTRODUCTION

Patients refractory, or responding only partially, to antipsychotic drugs are common in clinical practise. Medical diseases can present with psychotic symptoms or add to a psychotic picture and should not be missed. We report on a patient with schizophrenia whose treatment refractory psychosis remitted upon treatment of her obesity-hypoventilation syndrome (OHS).

CASE REPORT

A 63-year-old women previously diagnosed with hebephrenic schizophrenia developed treatment resistant auditory hallucinations along with extreme daytime fatigue and obesity. She was eventually diagnosed with Pickwickian syndrome or OHS and received treatment with continuous positive airway pressure (CPAP). Restoring the patient's alveolar hypoventilation with nocturnal CPAP led to the complete remission of hallucinations.

DISCUSSION

We suggest that this case highlights an issue that might become more common in the future with increasing prevalence of overweight. Indeed, some atypical neuroleptics might even counteract their own therapeutic effect by inducing excessive weight gain that increases the risk for OHS. We recommend taking a careful sleep history in schizophrenic patients with obesity and to perform a polysomnography in suspect cases.

[Obesity--hypoventilation syndrome: sometimes a difficult diagnosis]

Described in the specialty literature for over one century under the name of Pickwick syndrome, the obesity--hypoventilation syndrome (OHS) includes the triad: obesity--hypoventilation--hypersomnia. In Romania, this entity is rarely recognized and, despite the developments in specific investigations, the disease is frequently difficult to differentiate from other respiratory disorders during sleep. The authors try to clarify some issues related to pathophysiologic mechanism and contribution of mechanical factors or of respiratory nervous center etc. References are made about the leptin involvement. Clinical appearance and therapy modalities are added to the description of the disease.

[Chronic ronchopathy -- a nosological entity of pathological realization of upper airways obstruction]

A comprehensive examination and therapy of 90 snoring and apnea patients treated in an ENT clinic of the Russian State Medical University have established similar features of the diseases: pathological mechanisms, clinical manifestations, stages, outcome. This enables differential diagnosis and change of the syndromal diagnosis "pathological snoring" for a nosological one -- chronic ronchopathy. The term "ronchopathy" originates from a Greek word "ronhus"-- snoring; the term "chronic" means development of the disease due to chronic pathology of the upper airways and progression of a clinical symptom -- snoring.

Pickwickian syndrome: the challenge of severe sleep apnea

Pickwickian syndrome is a severe form of sleep apnea in obese persons which involves mechanical impairment of ventilation resulting in greatly compromised gas exchange. Manifestations of the syndrome are associated with deposits of adipose tissue around the abdomen and diaphragm and are completely reversible with weight loss. Since sleep apnea is now recognized as a significant chronic health problem, nurses in intensive care, medical-surgical, and home care settings are increasingly challenged to provide competent assessment, care, and rehabilitation of affected individuals.

Evaluation of patients with sleep apnea after tracheotomy

OBJECTIVE

To determine the effect of tracheotomy on polysomnographic and arterial blood gas data in patients with obstructive sleep apnea (OSA).

DESIGN

A retrospective study of all patients who underwent tracheotomy and were studied polysomnographically at the Johns Hopkins Sleep Disorders Center, Baltimore, Md, since 1981.

SETTING

A regional sleep disorders center.

PATIENTS

Twenty-eight patients (8 women and 20 men), aged 22 through 77 years. Patients were categorized into 2 groups on the basis of whether they had already undergone tracheotomy before polysomnography. Group 1 patients all had a polysomnographic diagnosis of OSA before tracheotomy. They were further subdivided on the basis of whether cardiopulmonary decompensation had been absent (group 1a, n=10) or present (group 1b, n=13). Group 2 patients (n=5) had undergone tracheotomy to treat upper airway obstruction that developed after non-apnea-related upper aerodigestive tract surgeries.

INTERVENTION

Tracheotomy.

MAIN OUTCOME MEASURES

Nocturnal non-rapid eye movement, apnea-hypopnea index, percentage oxyhemoglobin saturation, and arterial blood gas data.

RESULTS

Patients with OSA underwent tracheotomy as definitive treatment for the apnea (n=15), to prevent postoperative upper airway compromise after uvulopalatopharyngoplasty (n=7), and to treat upper airway compromise after non-apnea-related upper aerodigestive tract surgeries (n=6). Tracheotomy alleviated apnea in all 10 patients with uncomplicated sleep apnea (group 1a). For patients with OSA complicated by cardiopulmonary decompensation (group 1b), tracheotomy improved but did not eliminate sleep apnea in 7 of the 13 patients, despite overall improvement in arterial blood gas values. For patients whose sleep apnea had not been diagnosed polysomnographically before tracheotomy (group 2), tracheotomy was still required to treat OSA that had previously not been recognized.

CONCLUSIONS

Tracheotomy effectively treated patients with uncomplicated OSA, but was much less effective in treating patients with OSA and cardiopulmonary decompensation. In patients who underwent tracheotomy in conjunction with other upper aerodigestive tract surgeries, concomitant obstructive sleep apnea often required continued use of a tracheotomy to maintain upper airway patency.

Obesity hypoventilation [corrected] syndrome in the differential diagnosis of a pulmonary mass

Dyspnea and cyanosis are common presenting manifestations of cardiopulmonary disease. When these findings occur in a cigarette smoker with an apparent pulmonary mass on chest radiograph, the differential diagnosis rapidly narrows to a short list of possibilities that include pulmonary neoplasm, pulmonary infection and pulmonary infarction. Pulmonary hypertension with pulmonary arterial enlargement and hypoxia secondary to alveolar hypoventilation should also, however, be included as a diagnostic possibility in the appropriate setting because the evaluation and treatment of this entity may differ markedly.

[The Pickwick syndrome. From literary speculations to sleep research]

The "wonderfully fat boy" Joe described in The Pickwick Papers, by Charles Dickens, is remarkable for his glorious appetite and many attacks of sleep during the day. His medical condition was introduced as the Pickwick syndrome by Burwell et al. in 1956. For some 20 years this was an important stimulus for sleep research. Some literary and historical aspects of The Pickwick Papers are presented. The many diagnoses given to poor Joe are discussed. This diagnostic survey may still be of interest, even if the syndrome has virtually disappeared from medical literature. How does the Pickwick syndrome, as doctors today see it, fit Dickens' original description? Did Joe really suffer from the Pickwick syndrome?

Disk edema in an overweight woman

A 46-year-old extremely obese black woman presented with headaches, blurred vision, and visual obscurations. Her exam was notable for bilateral severe papilledema, retinal hemorrhages, and lethargy. Her CAT scan was normal, and a spinal tap revealed a very high opening pressure. Although this patient's presentation mimicked pseudotumor cerebri, the lethargy and retinal hemorrhages were atypical. Her hospital evaluation was notable for elevation of the serum bicarbonate level, and she was subsequently found to have hypoxia and hypercapnia on a blood gas. The patient was diagnosed as Pickwickian syndrome, with obstructive sleep apnea. Treatment of the pulmonary problem resulted in dramatic improvement in her eye findings and her lethargy, and optic nerve sheath fenestration was not necessary.

Airway management in obesity hypoventilation syndrome

The role of tracheostomy is limited in the obesity hypoventilation syndrome unless severe upper airway obstruction exists. If it is performed, special techniques must be applied to overcome the problems associated with tracheostomy in the morbidly obese patient. If attention is paid to these details, however, tracheostomy provides clinically important benefits in this difficult clinical situation.

"Near miss" death in obstructive sleep apnea: a critical care syndrome

OBJECTIVE

The objective of this study was to alert critical care physicians to the syndrome of obstructive sleep apnea with respiratory failure ("near miss" death) and to elucidate characteristics that might allow earlier recognition and treatment of such patients.

DESIGN

We examined clinical and laboratory characteristics of eight patients with obstructive sleep apnea presenting to the ICU with respiratory failure. These characteristics were compared with those of eight stable apnea patients of similar severity but without a history of presentation with respiratory failure.

SETTING

Medical ICU and pulmonary outpatient clinic at the Houston Veterans Administration Medical Center, a teaching hospital affiliated with Baylor College of Medicine.

PATIENTS

Eight patients with obstructive sleep apnea who presented in, or developed, acute respiratory failure requiring tracheal intubation and mechanical ventilation were matched to eight stable obstructive sleep apnea outpatients from the chest clinic.

MEASUREMENTS AND MAIN RESULTS

The records of these 16 patients were reviewed and multiple characteristics that might predict these obstructive sleep apnea patients prone to respiratory failure and death (called the "near miss" death group; n = 8) were examined. The mean age of the near miss group was 57 yrs. All eight patients presented with respiratory acidosis (mean pH 7.22), hypercarbia (mean PaCO2 82 torr [10.9 kPa]), and hypoxemia (mean PaO2 45 torr [6.0 kPa]). Six of the eight patients had concomitant chronic obstructive pulmonary disease as determined by clinical characteristics and spirometry. Predisposing factors included facial trauma, lower respiratory tract infections or bronchospasm, and use of pain medication. All but one of the near miss subjects had awake hypercarbia (mean PaCO2 49 torr [6.5 kPa]) and hypoxemia (mean PaO2 58 torr [7.7 kPa]) during periods of clinical stability while only two controls had concomitant chronic obstructive pulmonary disease and none had hypercarbia. The prevalence of a history of wheezing and prior hospitalization for "respiratory problems" were greater in the near miss group. Once cured of apnea, no patient presented with recurrence of respiratory failure in follow-up ranging from 6 to 80 months, and cor pulmonale recurred in only one patient during subsequent onset of central apneas.

CONCLUSION

Patients with obstructive sleep apnea who have concomitant chronic obstructive pulmonary disease or hypercarbia and hypoxemia are more prone to develop severe respiratory failure and probable death than those patients with apnea alone. The current study shows that recurrent respiratory failure and presumably mortality from this acute complication can be reversed with effective treatment of the obstructive apnea.