We describe a single-posture method for deriving the proportionality constant (K) between rib cage (RC) and abdominal (AB) amplifiers of the respiratory inductive plethysmograph (RIP). Qualitative diagnostic calibration (QDC) is based on equations of the isovolume maneuver calibration (ISOCAL) and is carried out during a 5-min period of natural breathing without using mouthpiece or mask. In this situation, K approximates the ratio of standard deviations (SD) of the uncalibrated changes of AB-to-RC volume deflections. Validity of calibration was evaluated by 1) analyzing RIP waveforms during an isovolume maneuver and 2) comparing changes of tidal volume (VT) amplitude and functional residual capacity (FRC) level measured by spirometry (SP) with RIP values. Comparisons of VT(RIP) to VT(SP) were also obtained in a variety of postures during natural (uninstructed) preferential RC and AB breathing and with voluntary changes of VT amplitude and FRC level. VT(RIP)-to-VT(SP) comparisons were equal to or closer than published reports for single posture, ISOCAL, multiple- and linear-regression procedures. QDC of RIP in supine posture with comparisons to SP in that posture and others showed better accuracy in horizontal than upright postures.

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Placement and use of pulmonary artery catheters (PACs) carry potential risks. The authors describe a case of a patient who developed massive hemoptysis after placement of a PAC that caused a rupture of the pulmonary artery with pseudoaneurysm formation. Treatment was successfully achieved with transcatheter coil embolization. Pulmonary artery rupture and pseudoaneurysm formation are among the most serious complications of PAC use because of the associated risk of mortality. Patients with this complication may be asymptomatic or may present with variable amounts of hemoptysis immediately or days after using a PAC. The gold standard diagnostic test is pulmonary angiography, and the treatment of choice for most patients is transcatheter embolization. Physicians and other health care personnel handling these catheters should be familiar with the specific PAC balloon's inflation limits to avoid complications that may injure the patient.

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