Clinical Research

Obesity Surgery

, Volume 21, Issue 4, pp 485-491

First online:

Open Access This content is freely available online to anyone, anywhere at any time.

The Relationship Between Anthropometric Measures, Blood Gases, and Lung Function in Morbidly Obese White Subjects

  • Anne-Marie GabrielsenAffiliated withThe Morbid Obesity Center, Vestfold Hospital TrustMedical Department, Vestfold Hospital Trust
  • , May Brit LundAffiliated withDepartment of Respiratory Medicine, Oslo University Hospital Rikshospitalet
  • , Johny KongerudAffiliated withDepartment of Respiratory Medicine, Oslo University Hospital Rikshospitalet
  • , Karl Erik VikenAffiliated withMedical Department, Vestfold Hospital Trust
  • , Jo RøislienAffiliated withThe Morbid Obesity Center, Vestfold Hospital TrustDepartment of Biostatistics, Institute of Basic Medical Sciences, University of Oslo
  • , Jøran HjelmesæthAffiliated withThe Morbid Obesity Center, Vestfold Hospital Trust Email author 



Obesity may cause adverse effects on the respiratory system. The main purpose of this study was to investigate how various measures of obesity are related to arterial blood gases and pulmonary function.


This is a cross-sectional study of consecutive morbidly obese patients with normal lung function. Blood gas samples were taken from the radial artery after 5 min of rest with subjects sitting upright. Lung function measurements included dynamic spirometry, static lung volumes, and gas diffusing capacity.


The 149 patients (77% women) had a mean (SD) age of 43 years (11 years) and BMI of 45.0 kg/m2 (6.3 kg/m2). The mean expiratory reserve volume (ERV) was less than half (49%) of predicted value, whilst most other lung function values were within predicted range. Forty-two patients had an abnormally low pO2 value (<10.7 kPa [80 mmHg]), while eight patients had a high pCO2 value (>6.0 kPa [45 mmHg]). All anthropometric measures correlated significantly with decreasing pO2 and increasing pCO2 (all P values < 0.05). BMI, neck circumference (NC), and waist circumference (WC) were negatively correlated with ERV (r = −0.25, −0.19, −0.21, respectively, all P values < 0.05). Multiple linear regression showed that BMI, WC, and NC were significantly associated with pO2 after adjustments for age, gender, and pack-years (all P values < 0.001). The models explained 34–36% of the variations in pO2. BMI, NC, and WC were also significantly associated with pCO2 (all P values < 0.05).There was no significant association between waist-to-hip ratio and blood gases (both P values > 0.27).


Both central and overall obesity were associated with unfavorable blood gases and low ERV.


Lung function Anthropometry Obesity Blood gases