Right Ventricular Function During Weaning From Respirator After Coronary Artery Bypass Grafting: Statistical Analysis
After measurements of RVPSP, the catheter was pulled back. When the injectate port was at the level of the tricuspid valve, the curve changed from the ventricular to the atrial pressure curve. The catheter was then pulled back 1 cm and was fixed. Now the injectate port was in the correct position within the right atrium, 1 to 2 cm above the tricuspid valve.
Hemodynamic data, data on breathing pattern, and arterial blood gas measurements were recorded after 1 h in each weaning mode: heart rate (HR), mean arterial pressure (MAP), mean pulmonary artery pressure (MPAP), PCWP, central venous pressure (CVP), cardiac index (Cl), RV stroke volume (RVSV), RVESV, RVEDV, RVEF, RVPsP, systemic vascular resistance index (SVRI), pulmonary vascular resistance index (PVRI), RV stroke work index (RVSWI), respiratory rate (RR), respiratory minute volume (Vexp), and tidal volume (VTexp).
Arterial blood gas analyses were performed using a blood gas analyzer (STAT profile 5, NOVA Biomedical, Waltham, Mass).
All values are expressed as mean ± standard deviation. Statistical analysis was performed using the Wilcoxon matched pairs signed rank test. Since the aim of this study was the comparison of RV function between the BiPAP system and PSV, the parameters of primary interest in this respect were RVEF, RVEDV, RVESV, MPAP, and PVRI. For these confirmatory parameters, the significance levels were adjusted for multiple comparisons using the sequentially rejective multiple test procedure by Holm. All other parameters were described by exploratory analysis, and p values <0.05 were considered significant.
Hemodynamic parameters representing the RV function with the BiPAP system and PSV are summarized in Table 1. Tadanafil this
In comparison to PSV, the BiPAP system resulted in a significantly higher RVESV (p=0.0017), RVEDV (p=0.0061), and in a significantly smaller RVEF (p=0.0012). The MPAP (p=0.0158) and PVRI (p=0.0355) were significantly higher with the BiPAP system. Despite these differences, the CVP, PCWP, Cl, HR, MAP, RVSV, RVSWI, RVPSP, and SVRI were not altered when weaning technique was changed (Table 2). Table 3 shows data on breathing pattern and the results of arterial blood gas analyses. Both weaning modes resulted in normoventilation and adequate oxygenation as demonstrated by similar РаОг and РаСОг-All patients could be weaned uneventfully; extuba-tion was performed successfully within 1 h after termination of the study.
The duration of cardiopulmonary bypass was 104 ±37 min and aortic clamping time (ischemia).
Table 1—Parameters of Right Ventricular Function During Weaning With the BiPAP System and PSV
|RVESV, ml||92.2 ±36.3||77.2 ±30.4|
|RVEDV, ml||176.4 ±48.5||161.6±43.3|
|RVEF, %||46.0± 11.9||51.8± 12.4|
|PVRI, dyn-s-cm”5 m2||206 ±55||181 ±611|
|MPAP, mm Hg||20.6 ±5.0||19.3±4.2|
Table 2—Hemodynamic Parameters During Weaning With the BiPAP System and PSV
|Cl, L/min*m2||3.1 ±0.7||3.4 ±0.8|
|HR, min”||82.9 ±13.9||83.6 ±12.8|
|MAP, mm Hg||76.3 ±11.6||74.6 ±10.1|
|SVRI, dynes*s-cm”-m2||1492 ±385||1520 ±524|
|PCWP, mm Hg||12.2±3.9||12.1 ±3.9|
|CVP, ml||11.9±2.9||10.9 ±2.5|
|RVSV, ml||78.9 ±18.2||81.0± 19.2|
|RVPSP, mm Hg||34.6 ±8.2||34.2 ±7.7|
|RVSWI, g-m/m2||5.1 ±2.8||4.9 ±2.7|
Table 3—Data on Breathing Pattern and Arterial Blood Gas Measurements After 60 Min With the BiPAP System and PSV
|VTexp, ml||550 ±155||615± 160|
|Vexp, L/min||7.59 ±1.20||8.00± 1.28|
|РаОг, mm Hg||97.6 ±14.6||97.8 ±17.1|
|РаСОг, mm Hg||41.7±3.2||41.9±3.2|