title: Ventilatory pattern and chest wall mechanics during ketamine anesthesia in humans.
abstract: The effects of anesthetic doses of ketamine (iv bolus of 3 mg X kg-1 followed by a continuous infusion of 20 micrograms X kg-1 X min-1) on functional residual capacity (FRC) measured by the helium dilution method and on the breathing pattern recorded by a noninvasive method (NIM) based on chest wall circumference changes were studied in 14 ASA P.S. I patients. Ketamine anesthesia was associated with: 1) the maintenance of FRC, minute ventilation, and tidal volume; 2) an increase in rib cage contribution to tidal breathing; and 3) an alteration of volume-motion relationships of the chest wall compartments. It is concluded that: 1) in contrast to volatile anesthetic agents, ketamine anesthesia has a sparing effect on intercostal muscle activity, which may explain the maintenance of FRC; and 2) changes in chest wall geometry and compliance induced by anesthetic agents must be taken into account for NIM to be valid.
mesh_terms: D000328:Adult; D000771:Anesthesia, Intravenous; D002138:Calibration; D005652:Functional Residual Capacity; D006801:Humans; D007649:Ketamine / Q000494:pharmacology*; D008176:Lung Volume Measurements / Q000592:standards; D008297:Male; D009068:Movement; D012119:Respiration / Q000187:drug effects*; D012132:Respiratory Muscles / Q000187:drug effects; D013909:Thorax / Q000187:drug effects* / Q000502:physiology; D013990:Tidal Volume
chemical_list: D007649:Ketamine