Canadian journal of anaesthesia = Journal canadien d'anesthésie
-
Hypoxic pulmonary vasoconstriction (HPV) is a fundamental physiological process whereby ventilation/perfusion matching is optimized through the constriction of the pulmonary circulation supplying poorly ventilated lung units. In their 1981 paper in the Journal, Noble, Kay, and Fisher used a series of animal experiments to show that alveolar carbon dioxide (CO2) plays a critical role in the regulation of hypoxic pulmonary vasoconstriction. At physiological concentrations, CO2 potentiates the HPV response, and the absence of alveolar CO2 blunts HPV. The enhancement of HPV by CO2 resulted in reduced perfusion of specific hypoxic lung regions, thereby improving systemic oxygenation in lung-ventilated dogs.
-
This study was undertaken to determine the contribution of postoperative pain to the known changes that occur to respiratory function in the postoperative period. The authors studied changes in functional residual capacity (FRC) and vital capacity (VC) either in the postanesthesia care unit or on postoperative day one in eight relatively healthy adult patients having upper abdominal surgery. ⋯ Epidural analgesia to a T4 sensory level resulted in a partial and statistically significant restoration of VC (from 37-55% of preoperative values) and a partial but statistically insignificant restoration of FRC (from 78-84% of preoperative values). The authors suggest that postoperative epidural analgesia may be able to decrease respiratory complications.