Читать книгу Manual of Equine Anesthesia and Analgesia - Группа авторов - Страница 223

 V/Q mismatching and intrapulmonary shunting are the major mechanisms responsible for the decrease in oxygenation during anesthesia.The distribution of ventilation changes in dorsal or lateral recumbency due to a decrease in FRC and regional differences in pleural pressures.Perfusion of the lungs changes due to a decrease in cardiac output, regional changes in vascular resistance, and inhibition of hypoxic pulmonary vasoconstriction.

 As the degree of right‐to‐left intrapulmonary shunting increases within the lung, the effect of increasing FiO2 on PaO2 decreases.

 A decrease in arterial CO2 removal from the lungs (e.g. with hypoventilation) with a resulting increase in PaCO2 is typically observed under general anesthesia.

 In general, with injectable and inhalational anesthetics, the minute ventilation and VT are decreased, while the f may be increased or decreased.

 The degree of respiratory depression with anesthetic agents is dose‐dependent and results from drug‐induced effects on the respiratory control centers.