LESSON OF THE MONTH Clinical Medicine 2017 Vol 17, No 6: 578–81 Lesson of the month 1: Obesity hypoventilation (Pickwickian) syndrome: a reversible cause of severe pulmonary hypertension Authors: F r a z e r W a r r i c k e r , A Z a fi r I s l a m B a n d B e n o y N S h a h C Obesity hypoventilation syndrome (OHS) is a condition in which Table 1. Diagnostic criteria for obesity an individual with a body mass index >30 kg/m 2 develops hypoventilation syndrome daytime alveolar hypoventilation (defined as a resting PaCO2 >45 mmHg) that cannot be attributed to other pathologies. Criteria Description 2 It is a condition with increasing prevalence and rising cost to Obesity Body mass index >30 kg/m ABSTRACT healthcare systems worldwide. Right heart failure and pulmonary hypertension are well-known complications of this syndrome. Hypoventilation Awake arterial hypercapnia (PaCO2 >45 mmHg) Here, we present the case of a female patient with OHS who Sleep-disordered Polysomnography reveals sleep presented to our centre with severe pulmonary hypertension, breathing hypoventilation with nocturnal hypercapnia which resolved with appropriate treatment. We also review this with or without obstructive apnea/hypopnea clinical condition and its diagnosis and management. events Rule out other Severe chronic obstructive pulmonary disease, K E Y W O R D S : obesity hypoventilation syndrome , Pickwickian causes of severe interstitial lung disease, chest wall syndrome , pulmonary hypertension , obstructive sleep apnoea hypoventilation disorders, thyroid disorders and congenital hypoventilation syndromes Introduction L e s s o n Obesity hypoventilation syndrome (OHS), also known as Pickwickian Syndrome, is an under-recognised condition that A 39-year-old Fijian woman presented to the cardiology clinic can cause respiratory failure, right heart failure and severe with a chronic history of exertional dyspnoea, with an acute pulmonary hypertension (PH). Individuals with OHS develop worsening over the past 3 months. Her exercise tolerance was daytime alveolar hypoventilation, resulting in hypercapnia and 50 yards (approximately 46 m). She denied chest pains or hypoxaemia, which cannot be attributed to other pathologies palpitations but complained of disturbed sleep and of having (Table 1 ). 1 Of patients with OHS, 90% also have obstructive to sleep in a chair. Her family also mentioned loud snoring at sleep apnoea (OSA), while the remaining 10% experience night and daytime somnolence. On examination, her weight and height were 132 kg and nocturnal hypoventilation but without frequent episodes of 2 apnoea. 2 In addition to respiratory impairment, OHS is also a 167 cm, respectively (BMI 47 kg/m ). Her resting blood pressure known cause of PH (Table 2 ). was 123/75 mmHg, her pulse was 100 beats per minute, with In recent years, the prevalence of OHS has markedly a resting oxygen saturation of 70% breathing room air. She increased; it is estimated that 0.3–0.4% of the general had no audible murmurs but did have a raised jugular venous population and up to 30% of inpatients with a body mass index pressure (JVP) with bilateral pitting oedema. She mobilised (BMI) >35 kg/m 2 might be affected. 3 Here, we present a recent no more than 10 m to undergo electrocardiography (ECG; case from our institute in which a young patient presenting which revealed sinus tachycardia with partial right bundle with breathlessness was found to have severe PH and respiratory branch block) and became acutely more breathless, with failure; after receiving a diagnosis of OHS and appropriate her oxygen saturation dropping to 60%. An urgent arterial blood gas sample revealed type 2 respiratory failure (pH 7.41, management, the patient now is well with no PH. – PaCO2 7.8 kPa, PaO 2 4.2 kPa and HCO3 36.6 mmol/L) with a markedly elevated bicarbonate level, implying chronic CO 2 retention. Transthoracic echocardiography (TTE) revealed an enlarged right heart with an estimated pulmonary arterial Authors: A CT2 Medicine, Department of Cardiology, University systolic pressure >90 mmHg, consistent with severe PH. Hospital Southampton, Southampton, UK ; B CT1 Medicine, She was urgently admitted to the coronary care unit and Department of Cardiology, University Hospital Southampton, treated with intravenous diuretics and low-flow oxygen. S o u t h a m p t o n , U K ; C consultant cardiologist, Department of Unfortunately, her condition deteriorated, requiring transfer Cardiology, University Hospital Southampton, Southampton, UK to the intensive care unit for non-invasive ventilation (NIV). 578 © Royal College of Physicians 2017. All rights reserved. CMJv17n6-LOM_Shah_Khan.indd 578 11/18/17 1:23 PM Lesson of the month Urgent CT pulmonary angiography revealed neither acute nor Table 2. Clinical classification of pulmonary chronic pulmonary emboli. hypertension Following bi-level positive airways pressure (BiPAP) Type of pulmonary Causes ventilation, repeat echocardiography 24 h after admission hypertension showed a reduction in her estimated right heart pressures from 90 mmHg to 60 mmHg. Given that the patient's pulmonary Grade 1 pressures had improved with oxygen, it was felt that idiopathic Pulmonary arterial Idiopathic PH was unlikely. A clinical diagnosis of OHS with chronic hypertension Heritable: (eg BMPR, ALK1, mutations) (untreated) OSA was made. The patient's symptoms improved with respiratory support and diuretics, and she made an Drugs and toxins excellent recovery, being discharged home 13 days after Connective tissue diseases admission with nocturnal NIV. Repeat echocardiography HIV infection before discharge showed further reduction of her right heart pressure to 31 mmHg. She was seen in the outpatient clinic Portal hypertension 4 months later, at which point she appeared very well and Congenital heart disease had no symptoms. Repeat echocardiography now showed Schistosomiasis undetectable right heart pressures, indicating normalisation of the pulmonary pressures (Fig 1 ). She continues with nocturnal Persistent pulmonary hypertension of NIV and no longer has poor sleep or daytime somnolence. the newborn Pulmonary veno- D i s c u s s i o n occlusive disease and/ or pulmonary capillary OHS was first described in 1956, at which time the condition haemangiomatosis was referred to as ‘Pickwickian syndrome’ after the character Joe, an overweight red-faced boy in the novel The Pickwick Grade 2 Papers by Charles Dickens. 4 OHS can present with a range Pulmonary hypertension LV systolic dysfunction of symptoms, from complaints of snoring and daytime resulting from left heart LV diastolic dysfunction somnolence by family members to breathlessness, fatigue, mood disease disorders and morning headaches. The past medical history can Valvular heart disease reveal conditions that provide alternative explanations for CO2 Grade 3 retention, including mechanical disorders, such as lung diseases Pulmonary hypertension Chronic obstructive pulmonary disease and kyphoscoliosis, neuropathies, and central nervous system abnormalities, such as prior stroke and severe hypothyroidism. resulting from lung Interstitial lung disease diseases and/or hypoxia A careful social history is required to screen for potential Other pulmonary diseases with mixed respiratory suppressants, such as alcohol and narcotic drugs. restrictive and obstructive patterns Physical examination invariably reveals significant obesity Sleep-disordered breathing and frequently an elevated resting respiratory rate, and can show features of right heart failure, such as peripheral oedema. Alveolar hypoventilation disorders Several initial investigations are warranted; a full blood count Chronic exposure to high altitude can reveal erythrocytosis and thyroid function should also be Developmental abnormalities checked. ECG frequently reveals sinus tachycardia, can show right bundle branch block, and often right heart abnormalities, Grade 4 including elevated pulmonary arterial pressures. Arterial Chronic thromboembolic blood gas analysis should be performed and usually reveals a pulmonary hypertension compensated respiratory acidosis, with elevated PaCO 2 , reduced Grade 5 PaO2 and elevated serum bicarbonate levels. OHS is associated with Grade 3 pulmonary hypertension. 7 When diagnosing PH, Pulmonary hypertension Haematological disorders (eg the gold standard investigation is right heart catheterisation with unclear and/ myeloproliferative disorders, splenectomy) (RHC); however, TTE is commonly used for screening and or multifactorial Systemic disorders (eg sarcoidosis, monitoring of the disease because it is non-invasive, cheaper, mechanisms pulmonary Langerhans cell histiocytosis, more widely available and has good diagnostic accuracy.8 lymphangioleiomyomatosis, Treatment aims for patients with OHS are based on neurofibromatosis, vasculitis) minimising morbidity and mortality by normalising arterial Metabolic disorders (eg glycogen CO2 levels. Other goals include the prevention of oxygen storage disease, Gaucher's disease, desaturation, reversal of erythrocytosis, cor pulmonale and 9 thyroid disorders) symptomatic relief of daytime somnolence. These goals are achieved through a multidisciplinary approach, with Others: tumoural obstruction, fibrosing the mainstay treatment being long-term lifestyle changes mediastinitis, chronic renal failure focused on weight loss.10 Weight loss of at least 10 kg results ALK = anaplastic lymphoma kinase; BMPR = bone morphogenetic protein in a significant improvement in vital capacity and maximum receptor;