Dynamics of invasive pressure monitoring systems: clinical and laboratory evaluation

Seven pressure monitoring systems were evaluated in the clinical setting and in the laboratory to assess their adequacy for recording invasive blood pressures. We found that a large number of systems used in the clinical setting gave erroneous pressure results because of inadequate dynamic response. Results of testing similar systems in the clinical setting and under optimal laboratory conditions differed greatly. Four major findings were made: (1) Air bubbles in the monitoring systems near the transducer accounted for most of the variability of the dynamic characteristics of systems in the clinical setting; (2) simple catheter transducer system setups performed better, suggesting that simple "kits" be used; (3) membrane domes perform adequately if they are attached with care and according to the manufacturer's specifications; and (4) extension tubing was detrimental to the dynamic response of all systems, especially for pulmonary artery catheters. Fast-flush testing of pressure monitoring systems is needed to ensure the adequacy of dynamic response characteristics in the clinical setting. If the fast-flush characteristics are inadequate, physicians and nurses have the opportunity to troubleshoot the system and remove air bubbles and excessive tubing and to properly attach the transducer domes until optimal characteristics are obtained.