Fig. 7.

Examples of POs developed in the 1970s and 1980s. (a) Picture of Takuo Aoyagi. Reprinted with permission from IEEE. (b) OLV-5100 PO by Nihon Kohden Corporation, patented by T. Aoyagi. Shown is the main part of the device (left) and the ear probe attached (right). Reprinted from Severinghaus and Honda,⁶ with permission from the publisher. (c) Picture of Susumu Nakajima. Reprinted with permission from NHK World-Japan. (d) The world’s first clinical applications of POs: the test of Aoyagi’s device by S. Nakajima at Sapporo Misumai National Sanatorium with a patient with respiratory failure after thoracoplasty for tuberculosis treatment (left) and the first clinical application of a finger-clip PO (OXIMET Met-1471) at Misumai Sanatorium by S. Nakajima in a patient suffering from hypoxemia post-surgery. Both images were obtained by S. Nakajima, with permission for publication. Both original photos have been edited by us to improve the quality (color and contrast). (e) OXIMET Met-1471 PO (Minolta Camera, Co., Ltd.). Reprinted from Miyasaka et al.,⁴⁶ with permission from the publisher. (f) Biox II PO (Ohmeda). Picture from pulmonary function tests history.¹⁶⁰ (g) N-100 PO (Nellcor). Reprinted from Miyasaka et al.,⁴⁶ with permission from the publisher. (h) Biox 3700 PO (Ohmeda). Picture from DOTmed WebStore.¹⁶¹