title: Effect of Mild Hypercapnia on Lung Oxygenation in Sitting Position During Shoulder Arthroscopy Under General Anesthesia.
abstract: BACKGROUND Mild hypercapnia is permitted during surgeries in sitting position under general anesthesia to maintain cerebral regional oxygen saturation (rSO2). However, since hypoventilation may cause gas exchange impairment, we evaluated effects of mild hypercapnia on lung oxygenation during shoulder arthroscopy in sitting position. MATERIAL AND METHODS Forty patients were randomly allocated to a normocapnia group (ETCO2 35 mmHg, n=20) or a hypercapnia group (45 mmHg, n=20). The mean arterial pressure (MAP), heart rate (HR), and rSO2 were measured 5 min after intubation in supine position (T0), and at 2, 4, 6, 8, 10, 20, 30, 40, 50, and 60 min of remaining in sitting position (T1-10). Arterial blood gas was analyzed at T0 and T5. The oxygenation index (PaO2/FiO2) and dead-space ventilation ratio (Vd/Vt) were calculated. RESULTS There were no differences in PaO2/FiO2 at T0 and T5 between the 2 groups. At T5, the Vd/Vt was higher in the normocapnia group than in the hypercapnia group (p=0.04). The Vd/Vt at T5 increased from T0 in the normocapnia group. The incidence of cerebral desaturation in the hypercapnia group (0/20) was lower than in the normocapnia group (5/20) (p=0.047). Among rSO2, MAP, and HR, only changes in rSO2 over time between the 2 groups differed significantly (p=0.048). CONCLUSIONS Mild hypercapnia did not decrease lung oxygenation in sitting position, probably due to attenuation of the increase in dead-space ventilation ratio. Since hypercapnia maintained rSO2 without changes in oxygenation index and hemodynamic parameters, mild hypercapnia should be maintained during shoulder arthroscopy in sitting position under general anesthesia.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Gachon University, Gil Medical Center, Incheon, South Korea.
authors.forename: Hyun Jeong
authors.initials: HJ
authors.lastname: Kwak
authors.affiliation: Department of Anesthesiology and Pain Medicine, Gachon University, Gil Medical Center, Incheon, South Korea.
authors.forename: Ji Yeon
authors.initials: JY
authors.lastname: Lee
authors.affiliation: Department of Anesthesiology and Pain Medicine, Yonsei University College of Medicine , Seoul, South Korea.
authors.forename: Jong
authors.initials: J
authors.lastname: Wha Lee
authors.affiliation: Department of Anesthesiology and Pain Medicine, Gachon University, Gil Medical Center, Incheon, South Korea.
authors.forename: Hong Soon
authors.initials: HS
authors.lastname: Kim
authors.affiliation: Department of Anesthesiology and Pain Medicine, Gachon University, Gil Medical Center, Incheon, South Korea.
authors.forename: Ho Jin
authors.initials: HJ
authors.lastname: Hur
authors.affiliation: Department of Anesthesiology and Pain Medicine, Yonsei University College of Medicine , Seoul, South Korea.
authors.forename: Ji Young
authors.initials: JY
authors.lastname: Kim
mesh_terms: D000368:Aged; D000768:Anesthesia, General / Q000379:methods*; D062186:Arterial Pressure; D001182:Arthroscopy / Q000379:methods*; D001784:Blood Gas Analysis; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D006935:Hypercapnia / Q000097:blood / Q000378:metabolism*; D007040:Hypoventilation / Q000097:blood / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000008:administration & dosage* / Q000097:blood*; D011187:Posture; D012123:Pulmonary Ventilation; D012782:Shoulder / Q000601:surgery*
chemical_list: D010100:Oxygen