Objective: To evaluate non-invasive continuous hemodynamic (IQ System) monitoring in the differential diagnosis of dyspnea.
Methods: According to the diagnosis on discharge, 48 patients diagnosed as pulmonary dyspnea were enrolled in control group and 38 patients with cardiac dyspnea were in heart failure group. Each patient underwent IQ monitoring on admission and after recovery. The difference in the diagnosis on admission and on discharge, and the difference in IQ index were analyzed.
Results: (1) Clinical diagnosis: 7 patients in heart failure group were missed on admission as 5 were diagnosed as pneumonia and 2 were diagnosed as chronic obstructive pulmonary disease (COPD). One patient with pneumothorax in control group was misdiagnosed as heart failure. (2) Indexes of cardiac function: base impedance (Zo), maximum value of dz/dt (dz/dt max) and Heather index (HI) of heart failure group were markedly lower than those of control group (all P<0.001). The respective values were (19.0+/-3.5) Omega vs. (28.8+/-5.5) Omega, (0.76+/-0.42) Omega/s vs. (1.40+/-0.72) Omega/s, and (7.04+/-4.25) Omega/s2 vs. (13.60+/-6.36) Omega/s2. If Zo value of patients with dyspnea was 22 omicron or less, the sensitivity in diagnosing heart failure was 79 percent, and its specificity was 94 percent. If Zo value was 18.0 omicron or less, the sensitivity in diagnosing heart failure was 47 percent, and its specificity was 100 percent. (3) Comparison within groups: Indexes of cardiac function of control group did not change obviously and Zo, dz/dt max, HI, stroke volume (SV) and acceleration contraction index (ACI) values of heart failure group rose significantly after recovery. (4) Pre-ejection period (PEP) and left ventricular ejection time (VET) in both groups had no statistical significance in differences.
Conclusion: IQ System was valuable in differential diagnosis to judge if dyspnea is caused by heart failure. Zo, dz/dt max and HI, especially Zo, are reliable.