<prompt> All of the following criteria are required for diagnosis of obesity hypoventilation syndrome except-HypertensionSleep disorder breathingBMI30kgm2PaCO2 45 mmHg  <response>: Ans. is a i.e., Hypertension o Obesity hyoventilation syndrome OHS is defined as the triad of obesity, daytime hypoventilation, and sleep- disordered breathing in the absence of an alternative neuromuscular, mechanical or metabolic explanation for hypoventilation.Obesity hypoventilation syndromeObesityDay time hypoventilationSleep disordered breathingo OHS is defined as daytime hypercapnia and hypoxemia Paco2 45 mm Hg and Pao2 70 mm Hg at sea level in an obese patient body mass index 30 kgm2 with sleep-disordered breathing in the absence of any other cause of hypoventilation. It is important to recognize that OHS is a diagnosis of exclusion and should be distinguished from other conditions that are commonly associated with hypercapnia.Definition of Obesity Hypoventilation SyndromeRequired ConditionsDescriptionObesityo Body mass index 30 kgm2Chronic hypoventilationo Awake daytime hypercapniaPaCo2 45 mm Hg and Pao2 70 mm HgSleep-disordered breathingo Obstructive sleep apnea apneahypopnea index 5 eventsh, with or without sleep hypoventilation present in 90 of caseso Non-obstructive sleep hypoventilation apnea-hypopnea index 5 eventsh in 10 of casesExclusion of other causes of hypercapniao Severe obstructive airways diseaseo Severe interstitial lung diseaseo Severe chest-wall disorders eg, kyphoscoliosiso Severe hypothyroidismo Neuromuscular diseaseo Congenital central hypoventilation syndromeMechanisms bv which obesity can lead to chronic daytime hypercapnia Obesity Leptin resistance Increased mechanical load and weak respiratory muscles Obstructive sleep apnea upper-airway resistance Acute hypercapnia during sleep -Decreased Co3 response---Blunted ventilatory response-Increased serum HCO3- -Decreased HC03- excretion rate Chronic hypercapnia 