title: Combination of external chest wall oscillation with continuous positive airway pressure.
abstract: We studied the effects of continuous positive airway pressure (CPAP) on pulmonary gas exchange during external chest wall oscillation (ECWO), and the relationship with obesity, in nine patients with normal body weight (group 'N') and 10 obese patients (group 'O'). During ECWO with CPAP 5, PaCO2 decreased in group 'O' (6.0 (SD 0.8) to 5.6 (0.5) kPa, P<0.05), whereas it increased in group 'N' at all levels (P<0.01). Arterial PO(2) (P<0.001) was greater and PaCO2 (P<0.01) less in group 'N' during CPPV and ECWO plus CPAP. We also compared the haemodynamic effects of ECWO plus CPAP with those of continuous positive pressure ventilation (CPPV). ECWO plus CPAP and CPPV were applied for 30 min to 6 ASA III patients. Cardiac output (CI 2.7 (0.5) vs 2.1 (0.2) litre x min(-1) x m(-2), P<0.05) and stroke volume (SVI 49 (9) vs 32 (6) ml x m(-2), P<0.05) were greater during ECWO plus CPAP than with CPPV. ECWO is less effective in obese individuals than in those with normal body weight, and the effect of CPAP in overweight individuals is small.
authors.affiliation: Department of Anaesthesiology and Intensive Care Medicine, Justus-Liebig-University, Rudolf-Buchheim-Strasse 7, D-35385 Giessen, Germany.
authors.forename: S E
authors.initials: SE
authors.lastname: Scholz
authors.forename: J
authors.initials: J
authors.lastname: Sticher
authors.forename: G
authors.initials: G
authors.lastname: Häufler
authors.forename: M
authors.initials: M
authors.lastname: Müller
authors.forename: O
authors.initials: O
authors.lastname: Böning
authors.forename: G
authors.initials: G
authors.lastname: Hempelmann
mesh_terms: D000328:Adult; D000368:Aged; D000768:Anesthesia, General; D002302:Cardiac Output; D018592:Cross-Over Studies; D006439:Hemodynamics; D006612:High-Frequency Ventilation / Q000379:methods; D006801:Humans; D007430:Intraoperative Care / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000503:physiopathology; D011175:Positive-Pressure Respiration / Q000379:methods; D011659:Pulmonary Gas Exchange; D012121:Respiration, Artificial / Q000379:methods*; D015656:Respiratory Mechanics