title: Relationship between frequency of ventilation, airways and pulmonary artery pressures, cardiac output and tracheal tube deadspace.
abstract: Intravascular and airway pressures, cardiac output (CO) and blood gas tensions were measured in five adult patients after hepatobiliary surgery. They were ventilated at frequencies of 15, 100 and 200 breaths min-1 (bpm) with the respiratory fresh gas (RFG) supplied at the proximal and distal end of a Mallinckrodt Hi-Lo tracheal tube. The peak airway pressure (P AW) fell from 1.20 kPa at 15 bpm to 0.6 kPa at 100 bpm, rising again to 1.9 kPa at 200 bpm, and both changes were significant (P less than 0.05). The mean pulmonary artery pressure (PAMP) remained in the range 1.87-2.00 kPa (14-15 mmHg) at 15 and 100 bpm but rose to over 2.67 kPa (20 mmHg) at 200 bpm (P less than 0.05). Cardiac output, heart rate and systemic arterial pressure remained unchanged. A small but significant (P less than 0.05) reduction in PaCO2 occurred when the RFG was moved to the distal end of the tracheal tube. A theoretical analysis predicts that the minimal P AW to maintain CO2 hemostasis will occur between 30 to 100 bpm, which is reflected in the results of the present study.
mesh_terms: D000328:Adult; D000368:Aged; D000403:Airway Resistance; D001794:Blood Pressure; D002245:Carbon Dioxide / Q000494:pharmacology; D002302:Cardiac Output; D002320:Cardiovascular Physiological Phenomena; D006801:Humans; D007442:Intubation, Intratracheal; D008875:Middle Aged; D010366:Peak Expiratory Flow Rate; D011229:Preanesthetic Medication; D012119:Respiration; D012121:Respiration, Artificial; D013990:Tidal Volume
chemical_list: D002245:Carbon Dioxide