Comparison of the effect of 1:1 and 1:2 frequencies of intra-aortic balloon pump on hemodynamics of the patients undergoing coronary artery bypass graft surgery.

Background: Some patients require intra-aortic balloon pump (IABP) after coronary artery bypass graft (CABG) surgery. IABP can be adjusted to different frequencies such as 1:1, 1:2, or 1:3. In this study, we tried to compare the effect of 1:1 and 1:2 frequencies of IABP on hemodynamic status of the patients after CABG surgery.

Methods: In this experimental study, all patients using IABP after CABG surgery were entered the study as pretest and posttest groups. The study could not be blinded because of the clearness of posttest group for the same echocardiographist. The pretest group included patients using a 1:1 frequency of IABP device. The posttest group included patients in the pretest group who were exposed to a 1:2 frequency for 20 minutes. In both groups, on the moderate dose of inotropic support, hemodynamic parameters of patients including systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), heart rate (HR), cardiac output (CO), cardiac index (CI), stroke volume (SV), and velocity time integral (VTI) in the aorta during systole were measured. Both groups were compared using Wilcoxon signed rank test. SPSS software was used for analysis and P < 0.05 was considered to be statistically significant.

Results: Twelve patients were entered into the study. Three patients were excluded because of open chest and instability of vital signs. Nine patients completed the study. 3 patients were men and 6 were women. The mean age was 58.32 ± 13.18 years. MAP in 1:1 frequency was significantly higher than 1:2 (P = 0.043); however, there was no significant difference between 1:1 and 1:2 in other hemodynamic parameters, namely CO, CI, SV, HR, and VTI.

Conclusion: In patients on moderate dose of inotropes, IABP frequencies of 1:1 and 1:2 have the same effect on hemodynamic parameters such as CI, SBP, DBP, HR, and left ventricular outflow tract (LVOT) VTI; meanwhile, MAP remains higher in 1:1 frequency.