Relationship between metabolic syndrome and hypercapnia among obese patients with sleep apnea

Table 4 Summary of studies investigating the prevalence of daytime hypercapnia in Japanese obese patients with obstructive sleep apnea

Ref.	n	Population	Prevalence of daytime hypercapnia (PaCO2 ≥ 45 Torr)
Akashiba et al[25]	172	OSA (AHI ≥ 20 events/h) with Obesity (BMI ≥ 30 kg/m2)	32.0%
Harada et al[26]	162	OSA (AHI ≥ 5 events/h) with Obesity (BMI ≥ 30 kg/m2)	12.3%
Current research	97	OSA (AHI ≥ 30 events/h) with Obesity (BMI ≥ 30 kg/m2)	25.8%

AHI: Apnea-hypopnea index; BMI: Body mass index; OSA: Obstructive sleep apnea; PaCO₂: Arterial partial pressure of carbon dioxide.