MED-NERD

Obesity hypoventilation syndrome (OHS)/ Pickwickian Syndrome

 

 

Introduction:

Obesity hypoventilation syndrome (OHS) or Pickwickian Syndrome is a combination of obesity with(body mass index (BMI) ≥30 kg·m−2),  daytime hypercapnia (arterial carbon dioxide tension (PaCO2) ≥45 mmHg [5.9 kPa] at sea level) during wakefulness) due decreased ventilatory drive and capacity, and sleep disordered breathing in absence of alternate central, neuromuscular, respiratory/chest wall disease, or mechanical or metabolic explanation for hypoventilation.

 

OHS was described in 1886-1889 as overweight individuals complaining of somnolence, while obstructive sleep apnoea (OSA) was first described and reported in 1969. The term “Pickwickian syndrome” was first used in the 1950s after Charles Dickens’ first novel, “The Posthumous Papers of the Pickwick Club” in which a character, called Joe, was described as often falling asleep throughout the day and snoring while sleeping. The American Academy of Sleep Medicine (AASM) prefers the term OHS over the term Pickwickian syndrome as the latter is used to describe patients only with obesity or with obstructive sleep apnoea alone, not specific for OHS.

 

OHS patients  are usually associated with OSA and this represents about 90% of OHS patients, however, the presence of OSA is not necessary for the diagnosis of OHS. OSA is characterized by an apnoea/hypopnoea index (AHI) ≥5 events·h-1. About 70% of OHS patients having severe OSA (AHI ≥30 events·h-1).

 

According to the American Academy of Sleep Medicine (AASM), sleep hypoventilation in adults is defined by the following criteria:

-PaCO2  >55 mmHg for >10 min or an increase in PaCO2  >10 mmHg compared to an awake supine level to a value >50 mmHg for >10 min. To detect and observe the pattern of nocturnal sleep-disordered breathing (hypoventilation), an overnight polysomnography or respiratory polygraphy is required. However, polysomnography is not necessary for the diagnosis of OHS as not all patients have OSA.

 

OHS is diagnosed by exclusion of other causes of hypercapnia. The hallmark of the disease is obesity. Therefore, there is an relation between the prevalence of the disease and the BMI. OHS patients may undergo exacerbation of their condition leading to respiratory failure.

 

The highest grade of OHS defined recently by the European Respiratory Society was characterized by daytime hypercapnia in addition to cardiovascular (such as right-sided heart failure secondary to chronic hypoxemia and pulmonary hypertension) and metabolic disorders. Arterial hypertension and insulin resistance are common in OHS patients. OHS is associated with high rates of morbidity and mortality.

 

 

Description of OHS/Pickwickian syndrome over history:

 

-In 1886-1889, OHS was described as overweight individuals complaining of somnolence.

-A case describing a young overweight man with symptomatic alveolar hypoventilation that became diminished after weight loss, was reported.

-In 1950s, Richard Caton described a a 51-year-old patient complaining of severe daytime drowsiness with progressive weight gain. The patient had  chronic hypoxia and hypercapnia leading to nocturnal hypoventilation. The reduction in weight resulted in almost complete recovery from the drowsiness. Richard Caton asked for support from the Clinical Society of London. The president of this society found similarity between this case and the character named “Joe” in  Charles Dickens novel  “The Posthumous Papers of the Pickwick Club”.

-Another case was reported describing a sleepy card player with severe daytime somnolence that improved after reduction in weight.

-A Syndrome combined of obesity, cyanosis, somnolence, periodic breathing, and congestive cardiac failure, was found in six patients that improved after reduction in weight. These patients had the features of OHS.

-The American Academy of Sleep Medicine (AASM) defined the diagnostic criteria for OHS since 1999.

-The first electroencephalographic description of Pickwickian syndrome was published in German. They described periodic breathing with short apnoeas caused by rolling back of the tongue leading to airway obstruction. The symptoms were found associated with hypercapnia.

-Another case reported was an overweight female with daytime somnolence that had frequent apnoeas while sleeping. Weight loss improved the condition with nearly complete improvement of the daytime somnolence. The case was attributed to Pickwickian syndrome.

-The most recent international guidelines determined the cut-offs (Cut-off means: A measurable value of a screening variable which distinguishes screen positive from screen negative results) of both BMI and daytime hypercapnia. The determined cut-off for BMI is 30 kg·m−2 and the European Respiratory Society (ERS) Task Force outcomes determined the cut-off for PaCO2 which is 45 mmHg. The American Thoracic Society (ATS) included sleep disordered breathing as a diagnostic criteria for OHS.

 

See:

-Etiology and Epidemiology of Obesity hypoventilation syndrome (OHS)/Pickwickian Syndrome

-Clinical Presentation and Diagnosis of Obesity Hypoventilation Syndrome (OHS)/Pickwickian syndrome

 

References:

 

(1)Ghimire P, Sankari A, Kaul P. Pickwickian Syndrome. [Updated 2022 Nov 12]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK542216/ 

(2)Masa JF, Pépin JL, Borel JC, Mokhlesi B, Murphy PB, Sánchez-Quiroga MÁ. Obesity hypoventilation syndrome. Eur Respir Rev. 2019 Mar 14;28(151):180097.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9491327/ 

(3)Shah, N.M., Shrimanker, S. and Kaltsakas, G. (2021) Defining obesity hypoventilation syndrome, Breathe (Sheffield, England). U.S. National Library of Medicine. Available at:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8753617/ 

(4)Athayde RAB, Oliveira Filho JRB, Lorenzi Filho G, Genta PR. Obesity hypoventilation syndrome: a current review. J Bras Pneumol. 2018 Nov-Dec;44(6):510-518.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6459748/ 

(5) Jay  Summer (2022) Pickwickian syndrome: Symptoms, causes, and treatments, Sleep Foundation. Available at:

https://www.sleepfoundation.org/sleep-apnea/pickwickian-syndrome