Abstract
The purpose of this study is to clarify the influence of restrictive ventilatory impairment upon the pulmonary circulation when alveolar and blood gas composition are changed. The condition of restrictive ventilatory impairment was producted by suppressing ventilatory response due to inhalation of O2 poor or CO2 rich gas mixtures. The changes of pulmonary circulation and gas exchanges in this condition were compared with that without restrictive ventilatory impairment. Materials and Methods The normal dogs were used in moderately deep Nembutal anesthesia and divided into following three groups (Group I, IIa, IIb) 1) Group I ; Without restrictive ventilatory impairment ; The dogs were breathing spontaneously and not suppressed ventilatory response caused by 7% or 10% CO2 gas mixtures. 2) Group IIa ; With moderately restrictive ventilatory impairment ; The dogs were under controlled negative pressure ventilation placed in body respirator of our design and hyperventilation caused by inhalation of 7% O2 or 10% CO2 gas mixtures was restricted to about twice as ventilation at rest during air breathing. 3) Group IIb ; With highly restrictive ventilatory impairment ; The dogs were under equally controlled ventilation as normal by the same way as Group-IIa and ventilatory response was completely suppressed. Pulmonary arterial and right ventricular pressures were measured by electromanometer through two catheters introduced via jugular and recorded with ECG simultaneously. Cardiac output was measured by STEWART-HAMILTON'S method. The end-diastolic volume, residual blood volume and its ratio (RV/EDV) of right ventricle were estimated by modified BING-HOLT'S method. Blood gas analysis were performed by direct method using Combianalyser (GODART) Measurement of ventilatory values and another measurements or calculation were carried of pulmonary circulation and gas exchanges were performed on each experimental group before and about 15 minutes after starting inhaltioh of 7% O2 or 10% CO2 gas mixtures.
