• K Moriwaki, H Sasaki, M Kubota, A Higaki, T Yoshida, O Yuge, and M Morio.
• Department of Anesthesiology, Hiroshima University, Japan.
• J Clin Anesth. 1991 Sep 1; 3 (5): 361-6.

Study ObjectiveTo define the effect of the knee-chest position on pulmonary oxygenation in patients who underwent lower spinal operations under spinal anesthesia.DesignClinical, prospective study.SettingInpatient anesthesia and orthopedic surgery clinic at a municipal hospital.PatientsFifty-six patients (30 males and 26 females) who underwent lower spinal surgery under spinal anesthesia.InterventionsAfter administering hyperbaric tetracaine solution and fixing the anesthesia level in the supine position for 15 minutes, patients were turned to the knee-chest position. They breathed room air normally.Measurements And Main ResultsArterial blood gas tensions were measured in the supine position 15 minutes after administration of the tetracaine solution and 15 minutes after turning patients to the knee-chest position. Patients were classified into six groups according to their age: patients in their teens and 20s, 30s, 40s, 50s, 60s, and 70s. In the supine position, the mean values of the alveolar arterial oxygen tension difference (A-aDO2) of patients in their 50s, 60s, and 70s were significantly higher than those of patients in their teens and 20s, 30s, and 40s. In the knee-chest position, these high values of A-aDO2 in the older patient groups decreased significantly, thereby eliminating any significant difference in A-aDO2 among all age groups. To determine the mechanism of the improvement of pulmonary oxygenation in the elderly patients, the effect of the knee-chest position on lung volumes was studied in eight young volunteers.ConclusionA significant improvement of pulmonary oxygenation was seen in elderly patients who underwent lower spinal operation with spinal anesthesia when they were turned to the knee-chest position. The knee-chest position has a beneficial effect on pulmonary oxygenation in elderly patients who are given spinal anesthesia.

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