[Values of mixed venous oxygen saturation and difference of mixed venous-arterial partial pressure of carbon dioxide in monitoring of oxygen metabolism and treatment after open-heart operation].

OBJECTIVE

To explore the clinic values of early goal directed treatment (EGDT) with the target of mixed venous oxygen saturation (SvO₂) and difference of mixed venous-arterial partial pressure of carbon dioxide (Pv-aCO₂) in monitoring of oxygen metabolism and treatment for patients post open-heart operation.

METHODS

A prospective study was conducted. The adult patients admitted to Third People's Hospital of Chengdu from December 2011 to March 2014 with SvO₂<0.65 and blood lactic acid>2 mmol/L when admitted in intensive care unit (ICU) were selected on whom elective open-heart operation and pulmonary artery catheter examination were done. All patients received EGDT with the target of SvO₂≥0.65 and Pv-aCO₂<6 mmHg (1 mmHg=0.133 kPa) and were divided into three groups by the values of SvO₂and Pv-aCO₂at 6-hour after ICU admission: A group with SvO₂≥0.65 and Pv-aCO₂<6 mmHg, B group with SvO₂≥0.65 and Pv-aCO₂≥6 mmHg, and C group with SvO₂<0.65. Then the changes and prognosis of the patients in different groups were observed.

RESULTS

103 cases were included, 44 in A group, 31 in B group and 28 in C group. The acute physiology and chronic health evaluation II (APACHEII) score in group A were significantly lower than that in group B or C at 6, 24, 48 and 72 hours (T6, T24, T48, T72) of ICU admission (T6: 11.4 ± 5.8 vs. 13.9 ± 5.4, 13.7 ± 6.4; T24: 8.8 ± 3.7 vs. 10.8 ± 4.8, 11.8 ± 5.4; T48: 8.7 ± 4.1 vs. 9.6 ± 4.2, 10.2 ± 5.1; T72: 7.5 ± 3.4 vs. 8.6 ± 2.9, 9.2 ± 4.2, all P<0.05), and the sequential organ failure assessment (SOFA) showed the same tendency (T6: 6.5 ± 4.3 vs. 8.0 ± 3.8, 9.1 ± 4.5; T24: 6.6 ±3.6 vs. 8.6 ± 3.9, 8.5 ± 3.3; T48: 5.2 ± 3.4 vs. 7.0 ± 3.6, 7.6 ± 5.1; T72: 4.6 ± 2.4 vs. 5.8 ± 2.5, 6.8 ± 3.5, all P<0.05). The values of blood lactic acid (mmol/L) in group A and B were significant lower than that in group C at T6, T24, T48 and T72 (T6: 1.60 ± 0.95, 2.20 ± 1.02 vs. 2.55 ± 1.39; T24: 2.26 ± 1.26, 2.70 ± 1.36 vs. 3.34 ± 2.36; T48: 2.01 ± 1.15, 2.17 ± 1.51 vs. 2.42 ± 1.63; T72: 1.62±1.14, 1.64±0.75 vs. 2.11±1.29, all P<0.05). The time of machine ventilation (days) in group A or B was significantly shorter than that in group C (2.8 ± 2.0, 3.6 ± 2.3 vs. 5.0 ± 3.1, both P<0.05). ICU day (days) in group A was significant shorter than that in group C (4.6 ± 2.5 vs. 6.5 ± 3.7, P<0.05). The 7-day mortalities after operation in three groups were significantly different. Compared with group A (2.3%), the odds ratio (OR) in group B (22.6%) was 12.5 (P<0.05), group C (25.0%) 14.3 (P<0.05). The morbidity and 28-day mortality in three groups were not significantly different. Pv-aCO₂negatively correlated with cardiac index (CI, r=-0.685, P=0.000), but not correlated with blood lactic acid (r=0.187, P=0.080).

CONCLUSIONS

EGDT with the target of SvO₂≥0.65 and Pv-aCO₂<6 mmHg improved the general condition and tissue hypoxia, shortened the time of machine ventilation and duration of hospitalization in ICU, and decrease the 7-day mortality.